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Sample records for enriched germanium ge

  1. Energy levels of germanium, Ge I through Ge XXXII

    International Nuclear Information System (INIS)

    Sugar, J.; Musgrove, A.

    1993-01-01

    Atomic energy levels of germanium have been compiled for all stages of ionization for which experimental data are available. No data have yet been published for Ge VIII through Ge XIII and Ge XXXII. Very accurate calculated values are compiled for Ge XXXI and XXXII. Experimental g-factors and leading percentages from calculated eigenvectors of levels are given. A value for the ionization energy, either experimental when available or theoretical, is included for the neutral atom and each ion. section

  2. GRAN SASSO: Enriched germanium in action

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1991-12-15

    Two large crystals of carefully enriched germanium, one weighing 1 kilogram and the other 2.9 kilograms, and worth many millions of dollars, are being carefully monitored in the Italian Gran Sasso Laboratory in the continuing search for neutrinoless double beta decay.

  3. GRAN SASSO: Enriched germanium in action

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    Two large crystals of carefully enriched germanium, one weighing 1 kilogram and the other 2.9 kilograms, and worth many millions of dollars, are being carefully monitored in the Italian Gran Sasso Laboratory in the continuing search for neutrinoless double beta decay

  4. Synthesis and characterization of germanium monosulphide (GeS)

    Indian Academy of Sciences (India)

    This paper reports the growth of germanium monosulphide (GeS) single crystals by vapour phase technique using different transporting agents. The single crystallinity and composition of the grown crystals have been verified by transmission electron microscopy (TEM) and energy dispersive analysis of X-rays (EDAX) ...

  5. A segmented, enriched N-type germanium detector for neutrinoless double beta-decay experiments

    Science.gov (United States)

    Leviner, L. E.; Aalseth, C. E.; Ahmed, M. W.; Avignone, F. T.; Back, H. O.; Barabash, A. S.; Boswell, M.; De Braeckeleer, L.; Brudanin, V. B.; Chan, Y.-D.; Egorov, V. G.; Elliott, S. R.; Gehman, V. M.; Hossbach, T. W.; Kephart, J. D.; Kidd, M. F.; Konovalov, S. I.; Lesko, K. T.; Li, Jingyi; Mei, D.-M.; Mikhailov, S.; Miley, H.; Radford, D. C.; Reeves, J.; Sandukovsky, V. G.; Umatov, V. I.; Underwood, T. A.; Tornow, W.; Wu, Y. K.; Young, A. R.

    2014-01-01

    We present data characterizing the performance of the first segmented, N-type Ge detector, isotopically enriched to 85% 76Ge. This detector, based on the Ortec PT6×2 design and referred to as SEGA (Segmented, Enriched Germanium Assembly), was developed as a possible prototype for neutrinoless double beta-decay measurements by the MAJORANA collaboration. We present some of the general characteristics (including bias potential, efficiency, leakage current, and integral cross-talk) for this detector in its temporary cryostat. We also present an analysis of the resolution of the detector, and demonstrate that for all but two segments there is at least one channel that reaches the MAJORANA resolution goal below 4 keV FWHM at 2039 keV, and all channels are below 4.5 keV FWHM.

  6. Production, characterization and operation of {sup 76}Ge enriched BEGe detectors in GERDA

    Energy Technology Data Exchange (ETDEWEB)

    Agostini, M.; Bode, T.; Budjas, D.; Janicsko Csathy, J.; Lazzaro, A.; Schoenert, S. [Technische Universitaet Muenchen, Physik Department and Excellence Cluster Universe, Munich (Germany); Allardt, M.; Barros, N.; Domula, A.; Lehnert, B.; Wester, T.; Wilsenach, H.; Zuber, K. [Technische Universitaet Dresden, Institut fuer Kern- und Teilchenphysik, Dresden (Germany); Andreotti, E. [Institute for Reference Materials and Measurements, Geel (Belgium); Eberhard Karls Universitaet Tuebingen, Physikalisches Institut, Tuebingen (Germany); Bakalyarov, A.M.; Belyaev, S.T.; Lebedev, V.I.; Zhukov, S.V. [National Research Centre ' ' Kurchatov Institute' ' , Moscow (Russian Federation); Balata, M.; D' Andrea, V.; Ioannucci, L.; Junker, M.; Laubenstein, M.; Macolino, C.; Nisi, S.; Zavarise, P. [INFN Laboratori Nazionali del Gran Sasso and Gran Sasso Science Institute, Assergi (Italy); Barabanov, I.; Bezrukov, L.; Gurentsov, V.; Inzhechik, L.V.; Kazalov, V.; Kuzminov, V.V.; Lubsandorzhiev, B.; Yanovich, E. [Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation); Baudis, L.; Benato, G.; Walter, M. [Physik Institut der Universitaet Zuerich, Zurich (Switzerland); Bauer, C.; Heisel, M.; Heusser, G.; Hofmann, W.; Kihm, T.; Kirsch, A.; Knoepfle, K.T.; Lindner, M.; Maneschg, W.; Salathe, M.; Schreiner, J.; Schwingenheuer, B.; Simgen, H.; Smolnikov, A.; Strecker, H.; Wagner, V.; Wegmann, A. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Becerici-Schmidt, N.; Caldwell, A.; Liao, H.Y.; Majorovits, B.; O' Shaughnessy, C.; Palioselitis, D.; Schulz, O.; Vanhoefer, L. [Max-Planck-Institut fuer Physik, Munich (Germany); Bellotti, E.; Pessina, G. [Universita Milano Bicocca, Dipartimento di Fisica, Milan (Italy); INFN Milano Bicocca, Milan (Italy); Belogurov, S.; Kornoukhov, V.N. [Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation); Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Bettini, A.; Brugnera, R.; Garfagnini, A.; Hemmer, S.; Sada, C.; Von Sturm, K. [Dipartimento di Fisica e Astronomia dell' Universita di Padova, Padua (Italy); INFN Padova, Padua (Italy); Borowicz, D. [Jagiellonian University, Institute of Physics, Cracow (Poland); Joint Institute for Nuclear Research, Dubna (Russian Federation); Brudanin, V.; Egorov, V.; Kochetov, O.; Nemchenok, I.; Rumyantseva, N.; Shevchik, E.; Zhitnikov, I.; Zinatulina, D. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Cattadori, C.; Gotti, C. [INFN Milano Bicocca, Milan (Italy); Chernogorov, A.; Demidova, E.V.; Kirpichnikov, I.V.; Vasenko, A.A. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Falkenstein, R.; Freund, K.; Grabmayr, P.; Hegai, A.; Jochum, J.; Schmitt, C.; Schuetz, A.K. [Eberhard Karls Universitaet Tuebingen, Physikalisches Institut, Tuebingen (Germany); Frodyma, N.; Misiaszek, M.; Pelczar, K.; Wojcik, M.; Zuzel, G. [Jagiellonian University, Institute of Physics, Cracow (Poland); Gangapshev, A. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation); Gusev, K. [Joint Institute for Nuclear Research, Dubna (Russian Federation); National Research Centre ' ' Kurchatov Institute' ' , Moscow (Russian Federation); Technische Universitaet Muenchen, Physik Department and Excellence Cluster Universe, Munich (Germany); Hult, M.; Lutter, G. [Institute for Reference Materials and Measurements, Geel (Belgium); Klimenko, A.; Lubashevskiy, A. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Lippi, I.; Stanco, L.; Ur, C.A. [INFN Padova, Padua (Italy); Pandola, L. [INFN Laboratori Nazionali del Sud, Catania (Italy); Pullia, A.; Riboldi, S. [Universita degli Studi di Milano, Dipartimento di Fisica, Milan (Italy); INFN Milano (Italy); Shirchenko, M. [Joint Institute for Nuclear Research, Dubna (Russian Federation); National Research Centre ' ' Kurchatov Institute' ' , Moscow (Russian Federation); Collaboration: GERDA Collaboration

    2015-02-01

    The GERmanium Detector Array (GERDA) at the Gran Sasso Underground Laboratory (LNGS) searches for the neutrinoless double beta decay (0νββ) of {sup 76}Ge. Germanium detectors made of material with an enriched {sup 76}Ge fraction act simultaneously as sources and detectors for this decay. During Phase I of the experiment mainly refurbished semi-coaxial Ge detectors from former experiments were used. For the upcoming Phase II, 30 new {sup 76}Ge enriched detectors of broad energy germanium (BEGe)- type were produced. A subgroup of these detectors has already been deployed in GERDA during Phase I. The present paper reviews the complete production chain of these BEGe detectors including isotopic enrichment, purification, crystal growth and diode production. The efforts in optimizing the mass yield and in minimizing the exposure of the {sup 76}Ge enriched germanium to cosmic radiation during processing are described. Furthermore, characterization measurements in vacuum cryostats of the first subgroup of seven BEGe detectors and their long-term behavior in liquid argon are discussed. The detector performance fulfills the requirements needed for the physics goals of GERDA Phase II. (orig.)

  7. Production, characterization and operation of {sup 76}Ge enriched BEGe detectors in GERDA

    Energy Technology Data Exchange (ETDEWEB)

    Agostini, M. [Physik Department and Excellence Cluster Universe, Technische Universität München, Munich (Germany); Allardt, M. [Institut für Kern- und Teilchenphysik, Technische Universität Dresden, Dresden (Germany); Andreotti, E. [Institute for Reference Materials and Measurements, Geel (Belgium); Physikalisches Institut, Eberhard Karls Universität Tübingen, Tübingen (Germany); Bakalyarov, A. M. [National Research Centre “Kurchatov Institute”, Moscow (Russian Federation); Balata, M. [INFN Laboratori Nazionali del Gran Sasso and Gran Sasso Science Institute, Assergi (Italy); and others

    2015-02-03

    The GERmanium Detector Array (Gerda) at the Gran Sasso Underground Laboratory (LNGS) searches for the neutrinoless double beta decay (0νββ) of {sup 76}Ge. Germanium detectors made of material with an enriched {sup 76}Ge fraction act simultaneously as sources and detectors for this decay. During Phase I of theexperiment mainly refurbished semi-coaxial Ge detectors from former experiments were used. For the upcoming Phase II, 30 new {sup 76}Ge enriched detectors of broad energy germanium (BEGe)-type were produced. A subgroup of these detectors has already been deployed in Gerda during Phase I. The present paper reviews the complete production chain of these BEGe detectors including isotopic enrichment, purification, crystal growth and diode production. The efforts in optimizing the mass yield and in minimizing the exposure of the {sup 76}Ge enriched germanium to cosmic radiation during processing are described. Furthermore, characterization measurements in vacuum cryostats of the first subgroup of seven BEGe detectors and their long-term behavior in liquid argon are discussed. The detector performance fulfills the requirements needed for the physics goals of Gerda Phase II.

  8. Production, characterization and operation of Ge enriched BEGe detectors in GERDA

    Science.gov (United States)

    Agostini, M.; Allardt, M.; Andreotti, E.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Barros, N.; Baudis, L.; Bauer, C.; Becerici-Schmidt, N.; Bellotti, E.; Belogurov, S.; Belyaev, S. T.; Benato, G.; Bettini, A.; Bezrukov, L.; Bode, T.; Borowicz, D.; Brudanin, V.; Brugnera, R.; Budjáš, D.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; D'Andrea, V.; Demidova, E. V.; Domula, A.; Egorov, V.; Falkenstein, R.; Freund, K.; Frodyma, N.; Gangapshev, A.; Garfagnini, A.; Gotti, C.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Hegai, A.; Heisel, M.; Hemmer, S.; Heusser, G.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Ioannucci, L.; Janicskó Csáthy, J.; Jochum, J.; Junker, M.; Kazalov, V.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Klimenko, A.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lebedev, V. I.; Lehnert, B.; Liao, H. Y.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Majorovits, B.; Maneschg, W.; Misiaszek, M.; Nemchenok, I.; Nisi, S.; O'Shaughnessy, C.; Palioselitis, D.; Pandola, L.; Pelczar, K.; Pessina, G.; Pullia, A.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salathe, M.; Schmitt, C.; Schreiner, J.; Schulz, O.; Schütz, A.-K.; Schwingenheuer, B.; Schönert, S.; Shevchik, E.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Strecker, H.; Ur, C. A.; Vanhoefer, L.; Vasenko, A. A.; von Sturm, K.; Wagner, V.; Walter, M.; Wegmann, A.; Wester, T.; Wilsenach, H.; Wojcik, M.; Yanovich, E.; Zavarise, P.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zuber, K.; Zuzel, G.

    2015-02-01

    The GERmanium Detector Array ( Gerda) at the Gran Sasso Underground Laboratory (LNGS) searches for the neutrinoless double beta decay () of Ge. Germanium detectors made of material with an enriched Ge fraction act simultaneously as sources and detectors for this decay. During Phase I of theexperiment mainly refurbished semi-coaxial Ge detectors from former experiments were used. For the upcoming Phase II, 30 new Ge enriched detectors of broad energy germanium (BEGe)-type were produced. A subgroup of these detectors has already been deployed in Gerda during Phase I. The present paper reviews the complete production chain of these BEGe detectors including isotopic enrichment, purification, crystal growth and diode production. The efforts in optimizing the mass yield and in minimizing the exposure of the Ge enriched germanium to cosmic radiation during processing are described. Furthermore, characterization measurements in vacuum cryostats of the first subgroup of seven BEGe detectors and their long-term behavior in liquid argon are discussed. The detector performance fulfills the requirements needed for the physics goals of Gerda Phase II.

  9. Ge distribution in the Wulantuga high-germanium coal deposit in the Shengli coalfield, Inner Mongolia, northeastern China

    Energy Technology Data Exchange (ETDEWEB)

    Du, Gang [Key Laboratory of Marginal Sea Geology, Chinese Academy of Sciences (China)]|[Coal Geology Bureau of Inner Mongolia, Hohhot, 010051 (China); Zhuang, Xinguo [Institute of Sedimentary Basin and Mineral, Faculty of Earth Resources, China University of Geosciences, Hubei, 430074 (China)]|[State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Hubei, 430074 (China); Querol, Xavier; Izquierdo, Maria; Alastuey, Andres; Moreno, Teresa; Font, Oriol [Institute of Earth Science ' Jaume Almera' , CSIC, C/ LLuis Sole Sabaris s/n, 08028 Barcelona (Spain)

    2009-03-01

    The geological and geochemical controls of the Ge distribution in the Cretaceous Wulantuga high-Germanium coal deposit in the Shengli coal field, Inner Mongolia are investigated. This paper focuses mainly on the spatial distribution of the Ge contents in coal. The high-Ge coals mainly occur in three splits of the 6 coal in the southwestern part of the Shengli coal field. Mean germanium contents in the coal range from 32 to 820 {mu}g/g, with a mean value of 137 {mu}g/g, on a bulk coal basis (mean of 939 coal samples from 75 boreholes in the 6 coal seam) in an area of 2.2 km{sup 2}. The highest Ge content occurs SW of 6 coal seam, close to the margins of the coal basin, decreasing with a fan-shaped trend towards NW, the direction of the coal basin. There is an negative correlation between the mean Ge content and the thickness of the coal seam. Different distribution patterns of Ge content were found in vertical profiles. High Ge concentrations may occur in the middle parts of coal seams, at the bottom and/or the top of thick coal seams and inconspicuous variation. A major organic affinity was determined for Ge, with a special enriched in the banded bright and semibright coal. The high-Ge coals and the coalified wood in the sandstone overlaying the 6-1 coal highly enriched in Ge, As, Sb, W, Cs, Tl, Be, and Hg. The Late Jurassic silicified volcanic rocks in the NW of the Ge coal deposit relatively high enriched in Ge, Ga, Sb, As, Cs, Be, Ge and Hg. The correlation coefficients among the elements enriched showed marked variations at close sites in this deposit, suggesting a possible diagenetic origin of the geochemical anomaly. The main Ge anomaly was attributed to early Cretaceous hydrothermal fluids circulating through the fault systems and porous volcanic rocs, probably from the subjacent granitoid rocks. The fault systems, the porous coarse clastic rocks overlying coal seam and the lithotype of coal played an important role in the transport and trapping of Ge. A

  10. The processing of enriched germanium for the MAJORANA DEMONSTRATOR and R&D for a next generation double-beta decay experiment

    Science.gov (United States)

    Abgrall, N.; Arnquist, I. J.; Avignone, F. T., III; Barabash, A. S.; Bertrand, F. E.; Bradley, A. W.; Brudanin, V.; Busch, M.; Buuck, M.; Caja, J.; Caja, M.; Caldwell, T. S.; Christofferson, C. D.; Chu, P.-H.; Cuesta, C.; Detwiler, J. A.; Dunagan, C.; Dunstan, D. T.; Efremenko, Yu.; Ejiri, H.; Elliott, S. R.; Gilliss, T.; Giovanetti, G. K.; Goett, J.; Green, M. P.; Gruszko, J.; Guinn, I. S.; Guiseppe, V. E.; Haufe, C. R. S.; Henning, R.; Hoppe, E. W.; Jasinski, B. R.; Kidd, M. F.; Konovalov, S. I.; Kouzes, R. T.; Lopez, A. M.; MacMullin, J.; Martin, R. D.; Massarczyk, R.; Meijer, S. J.; Mertens, S.; Meyer, J. H.; Myslik, J.; O'Shaughnessy, C.; Poon, A. W. P.; Radford, D. C.; Rager, J.; Reine, A. L.; Reising, J. A.; Rielage, K.; Robertson, R. G. H.; Shanks, B.; Shirchenko, M.; Suriano, A. M.; Tedeschi, D.; Toth, L. M.; Trimble, J. E.; Varner, R. L.; Vasilyev, S.; Vetter, K.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Xu, W.; Yakushev, E.; Yu, C.-H.; Yumatov, V.; Zhitnikov, I.; Zhu, B. X.

    2018-01-01

    The MAJORANA DEMONSTRATOR is an array of point-contact Ge detectors fabricated from Ge isotopically enriched to 88% in 76 Ge to search for neutrinoless double beta decay. The processing of Ge for germanium detectors is a well-known technology. However, because of the high cost of Ge enriched in 76 Ge special procedures were required to maximize the yield of detector mass and to minimize exposure to cosmic rays. These procedures include careful accounting for the material; shielding it to reduce cosmogenic generation of radioactive isotopes; and development of special reprocessing techniques for contaminated solid germanium, shavings, grindings, acid etchant and cutting fluids from detector fabrication. Processing procedures were developed that resulted in a total yield in detector mass of 70%. However, none of the acid-etch solution and only 50% of the cutting fluids from detector fabrication were reprocessed. Had they been processed, the projections for the recovery yield would be between 80% and 85%. Maximizing yield is critical to justify a possible future ton-scale experiment. A process for recovery of germanium from the acid-etch solution was developed with yield of about 90%. All material was shielded or stored underground whenever possible to minimize the formation of 68Ge by cosmic rays, which contributes background in the double-beta decay region of interest and cannot be removed by zone refinement and crystal growth. Formation of 68Ge was reduced by a significant factor over that in natural abundance detectors not protected from cosmic rays.

  11. Selective Etching of Silicon in Preference to Germanium and Si0.5Ge0.5.

    Science.gov (United States)

    Ahles, Christopher F; Choi, Jong Youn; Wolf, Steven; Kummel, Andrew C

    2017-06-21

    The selective etching characteristics of silicon, germanium, and Si 0.5 Ge 0.5 subjected to a downstream H 2 /CF 4 /Ar plasma have been studied using a pair of in situ quartz crystal microbalances (QCMs) and X-ray photoelectron spectroscopy (XPS). At 50 °C and 760 mTorr, Si can be etched in preference to Ge and Si 0.5 Ge 0.5 , with an essentially infinite Si/Ge etch-rate ratio (ERR), whereas for Si/Si 0.5 Ge 0.5 , the ERR is infinite at 22 °C and 760 mTorr. XPS data showed that the selectivity is due to the differential suppression of etching by a ∼2 ML thick C x H y F z layer formed by the H 2 /CF 4 /Ar plasma on Si, Ge, and Si 0.5 Ge 0.5 . The data are consistent with the less exothermic reaction of fluorine radicals with Ge or Si 0.5 Ge 0.5 being strongly suppressed by the C x H y F z layer, whereas, on Si, the C x H y F z layer is not sufficient to completely suppress etching. Replacing H 2 with D 2 in the feed gas resulted in an inverse kinetic isotope effect (IKIE) where the Si and Si 0.5 Ge 0.5 etch rates were increased by ∼30 times with retention of significant etch selectivity. The use of D 2 /CF 4 /Ar instead of H 2 /CF 4 /Ar resulted in less total carbon deposition on Si and Si 0.5 Ge 0.5 and gave less Ge enrichment of Si 0.5 Ge 0.5 . These results are consistent with the selectivity being due to the differential suppression of etching by an angstrom-scale carbon layer.

  12. Measurement of energy transitions for the decay radiations of 75Ge and 69Ge in a high purity germanium detector

    Science.gov (United States)

    Aydın, Güral; Usta, Metin; Oktay, Adem

    2018-06-01

    Photoactivation experiments have a wide range of application areas in nuclear, particle physics, and medical physics such as measuring energy levels and half-lifes of nuclei, experiments for understanding imaging methods in medicine, isotope production for patient treatment, radiation security and transportation, radiation therapy, and astrophysics processes. In this study, some energy transition values of the decay radiations of 75Ge and 69Ge, which are the products of photonuclear reactions (γ, n) with germanium isotopes (75Ge and 69Ge), were measured. The gamma spectrum as a result of atomic transitions were analysed by using a high purity semiconductor germanium detector and the energy transition values which are presented here were compared with the ones which are the best in literature. It was observed that the results presented are in agreement with literature in error range and some results have better precisions.

  13. Germanium enrichment in supergene settings: evidence from the Cristal nonsulfide Zn prospect, Bongará district, northern Peru

    Science.gov (United States)

    Mondillo, Nicola; Arfè, Giuseppe; Herrington, Richard; Boni, Maria; Wilkinson, Clara; Mormone, Angela

    2018-02-01

    Supergene nonsulfide ores form from the weathering of sulfide mineralization. Given the geochemical affinity of Ge to Si4+ and Fe3+, weathering of Ge-bearing sulfides could potentially lead to Ge enrichments in silicate and Fe-oxy-hydroxide minerals, although bulk rock Ge concentrations in supergene nonsulfide deposits are rarely reported. Here, we present the results of an investigation into Ge concentrations and deportment in the Cristal supergene Zn nonsulfide prospect (Bongará, northern Peru), which formed from the weathering of a preexisting Mississippi Valley-type (MVT) sulfide deposit. Material examined in this study originates from drillcore recovered from oxidized Zn-rich bodies 15-20 m thick, containing 5-45 wt% Zn and Ge concentrations 100 ppm. Microanalysis and laser ablation-ICP-MS show that precursor sphalerite is rich in both Fe (mean Fe = 8.19 wt%) and Ge (mean Ge = 142 ppm). Using the mineral geothermometer GGIMFis—geothermometer for Ga, Ge, In, Mn, and Fe in sphalerite—proposed by Frenzel et al. (Ore Geol Rev 76:52-78, 2016), sphalerite trace element data from the Cristal prospect suggest a possible formation temperature ( T GGIMFis) of 225 ± 50 °C, anomalously high for a MVT deposit. Germanium concentrations measured in both goethite (mean values 100 to 229 ppm, max 511 ppm) and hemimorphite (mean values 39 to 137 ppm, max 258 ppm) are similar to concentrations measured in hypogene sphalerite. Additionally, the Ge concentrations recorded in bulk rock analyses of sphalerite-bearing and oxidized samples are also similar. A persistent warm-humid climate is interpreted for the region, resulting in the development of an oxidation zone favoring the formation of abundant Zn hydrosilicates and Fe hydroxides, both able to incorporate Ge in their crystal structure. In this scenario, Ge has been prevented from dispersion during the weathering of the Ge-bearing sulfide bodies and remains in the resultant nonsulfide ore.

  14. Germanium nitride and oxynitride films for surface passivation of Ge radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Maggioni, G., E-mail: maggioni@lnl.infn.it [Dipartimento di Fisica e Astronomia G. Galilei, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Laboratori Nazionali di Legnaro, Istituto Nazionale di Fisica Nucleare, Viale dell’Universita’2, I-35020 Legnaro, Padova (Italy); Carturan, S. [Dipartimento di Fisica e Astronomia G. Galilei, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Laboratori Nazionali di Legnaro, Istituto Nazionale di Fisica Nucleare, Viale dell’Universita’2, I-35020 Legnaro, Padova (Italy); Fiorese, L. [Laboratori Nazionali di Legnaro, Istituto Nazionale di Fisica Nucleare, Viale dell’Universita’2, I-35020 Legnaro, Padova (Italy); Dipartimento di Ingegneria dei Materiali e delle Tecnologie Industriali, Università di Trento, Via Mesiano 77, I-38050 Povo, Trento (Italy); Pinto, N.; Caproli, F. [Scuola di Scienze e Tecnologie, Sezione di Fisica, Università di Camerino, Via Madonna delle Carceri 9, Camerino (Italy); INFN, Sezione di Perugia, Perugia (Italy); Napoli, D.R. [Laboratori Nazionali di Legnaro, Istituto Nazionale di Fisica Nucleare, Viale dell’Universita’2, I-35020 Legnaro, Padova (Italy); Giarola, M.; Mariotto, G. [Dipartimento di Informatica—Università di Verona, Strada le Grazie 15, I-37134 Verona (Italy)

    2017-01-30

    Highlights: • A surface passivation method for HPGe radiation detectors is proposed. • Highly insulating GeNx- and GeOxNy-based layers are deposited at room temperature. • Deposition parameters affect composition and electrical properties of the layers. • The improved performance of a GeNx-coated HPGe diode is assessed. - Abstract: This work reports a detailed investigation of the properties of germanium nitride and oxynitride films to be applied as passivation layers to Ge radiation detectors. All the samples were deposited at room temperature by reactive RF magnetron sputtering. A strong correlation was found between the deposition parameters, such as deposition rate, substrate bias and atmosphere composition, and the oxygen and nitrogen content in the film matrix. We found that all the films were very poorly crystallized, consisting of very small Ge nitride and oxynitride nanocrystallites, and electrically insulating, with the resistivity changing from three to six orders of magnitude as a function of temperature. A preliminary test of these films as passivation layers was successfully performed by depositing a germanium nitride film on the intrinsic surface of a high-purity germanium (HPGe) diode and measuring the improved performance, in terms of leakage current, with respect to a reference passivated diode. All these interesting results allow us to envisage the application of this coating technology to the surface passivation of germanium-based radiation detectors.

  15. Ge14 Br8 (PEt3 )4 : A Subhalide Cluster of Germanium.

    Science.gov (United States)

    Kunz, Tanja; Schrenk, Claudio; Schnepf, Andreas

    2018-04-03

    Heating a metastable solution of Ge I Br to room temperature led to the first structurally characterized metalloid subhalide cluster Ge 14 Br 8 (PEt 3 ) 4 (1). Furthermore 1 can be seen as the first isolated binary halide cluster on the way from Ge I Br to elemental germanium, giving insight into the complex reaction mechanism of its disproportionation reaction. Quantum chemical calculations further indicate that a classical bonding situation is realized within 1 and that the last step of the formation of 1 might include the trapping of GeBr 2 units. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. GERDA, a GERmanium Detector Array for the search for neutrinoless ββ decay in 76Ge

    International Nuclear Information System (INIS)

    Pandola, L.; Tomei, C.

    2006-01-01

    The GERDA project, searching for neutrinoless double beta-decay of 76Ge with enriched germanium detectors submerged in a cryogenic bath, has been approved for installation at the Gran Sasso National Laboratory (LNGS), Italy. The GERDA technique is aiming at a dramatic reduction of the background due to radioactive contaminations of the materials surrounding the detectors. This will lead to a sensitivity of about 1026 years on the half-life of neutrinoless double beta decay. Already in the first phase of the experiment, GERDA will be able to investigate with high statistical significance the claimed evidence for neutrinoless double beta decay of 76Ge based on the data of the Heidelberg-Moscow experiment

  17. Strain relaxation of germanium-tin (GeSn) fins

    Science.gov (United States)

    Kang, Yuye; Huang, Yi-Chiau; Lee, Kwang Hong; Bao, Shuyu; Wang, Wei; Lei, Dian; Masudy-Panah, Saeid; Dong, Yuan; Wu, Ying; Xu, Shengqiang; Tan, Chuan Seng; Gong, Xiao; Yeo, Yee-Chia

    2018-02-01

    Strain relaxation of biaxially strained Ge1-xSnx layer when it is patterned into Ge1-xSnx fin structures is studied. Ge1-xSnx-on-insulator (GeSnOI) substrate was realized using a direct wafer bonding (DWB) technique and Ge1-xSnx fin structures were formed by electron beam lithography (EBL) patterning and dry etching. The strain in the Ge1-xSnx fins having fin widths (WFin) ranging from 1 μm down to 80 nm was characterized using micro-Raman spectroscopy. Raman measurements show that the strain relaxation increases with decreasing WFin. Finite element (FE) simulation shows that the strain component in the transverse direction relaxes with decreasing WFin, while the strain component along the fin direction remains unchanged. For various Ge1-xSnx fin widths, transverse strain relaxation was further extracted using micro-Raman spectroscopy, which is consistent with the simulation results.

  18. 75 FR 21680 - GE-Hitachi Global Laser Enrichment LLC;

    Science.gov (United States)

    2010-04-26

    ... Global Laser Enrichment LLC; Establishment of Atomic Safety and Licensing Board Pursuant to delegation by... over the following proceeding: GE-Hitachi Global Laser Enrichment LLC (GLE Commercial Facility) This... application of GE-Hitachi Global Laser Enrichment LLC for a license to possess and use source, byproduct, and...

  19. Formation of microcrystalline germanium (μc-Ge:H) films from inductively coupled plasma CVD

    International Nuclear Information System (INIS)

    Okamoto, Y.; Makihara, K.; Higashi, S.; Miyazaki, S.

    2005-01-01

    Inductively coupled RF plasma of H 2 -diluted GeH 4 gas was applied to the growth of hydrogenated microcrystalline germanium (μc-Ge:H) films on quartz in a reactor with an external single-turn antenna placed on quartz plate window parallel to the substrate. The deposition rate, the crystallinity and the thickness of an amorphous incubation layer formed in the early stages of the film growth were evaluated as functions of GeH 4 concentration, gas flow rate, substrate temperature and the distance between the antenna and the grounded substrate susceptor. We demonstrated the growth of highly crystalized Ge films at a rate as high as 0.9 nm/s at 250 deg. C using a 8.3% GeH 4 diluted with H 2

  20. Electrically Cooled Germanium System for Measurements of Uranium Enrichments in UF6 Cylinders

    International Nuclear Information System (INIS)

    Dvornyak, P.; Koestlbauer, M.; Lebrun, A.; Murray, M.; Nizhnik, V.; Saidler, C.; Twomey, T.

    2010-01-01

    Measurements of Uranium enrichment in UF6 cylinders is a significant part of the IAEA Safeguards verification activities at enrichment and conversion plants. Nowadays, one of the main tools for verification of Uranium enrichment in UF6 cylinders used by Safeguards inspectors is the gamma spectroscopy system with HPGe detector cooled with liquid nitrogen. Electrically Cooled Germanium System (ECGS) is a new compact and portable high resolution gamma spectrometric system free from liquid nitrogen cooling, which can be used for the same safeguards applications. It consists of the ORTEC Micro-trans-SPEC HPGe Portable Spectrometer, a special tungsten collimator and UF6 enrichment measurement software. The enrichment of uranium is determined by of quantifying the area of the 185.7 keV peak provided that the measurement is performed with a detector viewing an infinite thickness of material. Prior starting the verification of uranium enrichment at the facility, the ECGS has to be calibrated with a sample of known uranium enrichment, material matrix, container wall thickness and container material. Evaluation of the ECGS capabilities was performed by carrying out a field test on actual enrichment verification of uranium in UF6 cylinder or other forms of uranium under infinite thickness conditions. The results of these evaluations allow to say that the use of ECGS will enhance practicality of the enrichment measurements and support unannounced inspection activities at enrichment and conversion plants. (author)

  1. Defects reduction of Ge epitaxial film in a germanium-on-insulator wafer by annealing in oxygen ambient

    Directory of Open Access Journals (Sweden)

    Kwang Hong Lee

    2015-01-01

    Full Text Available A method to remove the misfit dislocations and reduce the threading dislocations density (TDD in the germanium (Ge epilayer growth on a silicon (Si substrate is presented. The Ge epitaxial film is grown directly on the Si (001 donor wafer using a “three-step growth” approach in a reduced pressure chemical vapour deposition. The Ge epilayer is then bonded and transferred to another Si (001 handle wafer to form a germanium-on-insulator (GOI substrate. The misfit dislocations, which are initially hidden along the Ge/Si interface, are now accessible from the top surface. These misfit dislocations are then removed by annealing the GOI substrate. After the annealing, the TDD of the Ge epilayer can be reduced by at least two orders of magnitude to <5 × 106 cm−2.

  2. Electromigration techniques for Ge(II) and Ge(IV) separation in germanium thio compounds

    Energy Technology Data Exchange (ETDEWEB)

    Facetti, J F; Vallejos, A [Asuncion Naciona Univ. (Paraguay). Inst. de Ciencias

    1971-01-01

    Using H.V. electromigration techniques, a good separation of the Ge(II) and Ge(IV) was achieved. The procedure was carried out in alkaline medium. And the final position of the separated species was established by, either neutron activation of the papa strips or chromatic reactions.

  3. Electromigration techniques for Ge(II) and Ge(IV) separation in germanium thio compounds

    International Nuclear Information System (INIS)

    Facetti, J.F.; Vallejos, A.

    1971-01-01

    Using H.V. electromigration techniques, a good separation of the Ge(II) and Ge(IV) was achieved. The procedure was carried out in alkaline medium. And the final position of the separated species was established by, either neutron activation of the papa strips or chromatic reactions

  4. GeMini: The Next Generation Mechanically-Cooled Germanium Spectrometer

    International Nuclear Information System (INIS)

    Burks, M.

    2008-01-01

    The next-generation mechanically-cooled germanium spectrometer has been developed. GeMini (GErmanium MINIature spectrometer) has been designed to bring high-resolution gamma-ray spectroscopy to a range of demanding field environments. Intended applications include short-notice and surprise inspections where positive nuclide identification of radioactive materials is required. GeMini weighs 2.75 kg (6 lbs) total including the detector, cryostat, cryocooler, batteries, electronics and readout. It is very low power allowing it to operate for 10 hours on a single set of rechargeable batteries. This instrument employs technology adapted from the gamma-ray spectrometer currently flying on NASA's Mercury MESSENGER spacecraft. Specifically, infrared shielding techniques allow for a vast reduction of thermal load. This in turn allows for a smaller, lighter-weight design, well-suited for a hand-held instrument. Two working prototypes have been built and tested in the lab. The target energy resolution is 3 keV fwhm or better for 1332 keV gamma-rays. The detectors currently achieve around 4.5 keV resolution, which is slightly higher than our goal due to microphonic noise. Our present work focuses on improving the resolution through mechanical and electronic means of reducing the microphonic noise. This paper will focus on the performance of the instrument and its applicability for inspectors in the field

  5. GeMini: The Next-Generation Mechanically-Cooled Germanium Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Burks, M

    2008-11-12

    The next-generation mechanically-cooled germanium spectrometer has been developed. GeMini (MINIature GErmanium spectrometer) has been designed to bring high-resolution gamma-ray spectroscopy to a range of demanding field environments. Intended applications include short-notice inspections, border patrol, port monitoring and emergency response, where positive nuclide identification of radioactive materials is required but power and liquid cryogen are not easily available. GeMini weighs 2.75 kg for the basic instrument and 4.5 kg for the full instrument including user interface and ruggedized hermetic packaging. It is very low power allowing it to operate for 10 hours on a single set of rechargeable batteries. This instrument employs technology adapted from the gamma-ray spectrometer currently flying on NASA's Mercury MESSENGER spacecraft. Specifically, infrared shielding techniques allow for a vast reduction of thermal load. This in turn allows for a smaller, lighter-weight design, well-suited for a hand-held instrument. Three working prototypes have been built and tested in the lab. The measured energy resolution is 3 keV fwhm at 662 keV gamma-rays. This paper will focus on the design and performance of the instrument.

  6. Growth and characterization of isotopically enriched 70Ge and 74Ge single crystals

    International Nuclear Information System (INIS)

    Itoh, K.

    1992-10-01

    Isotopically enriched 70 Ge and 74 Ge single crystals were successfully gown by a newly developed vertical Bridgman method. The system allows us to reliably grow high purity Ge single crystals of approximately 1 cm 3 volume. To our knowledge, we have grown the first 70 Ge single crystal. The electrically active chemical impurity concentration for both crystals was found to be ∼2 x cm -3 which is two order of magnitude better that of 74 Ge crystals previously grown by two different groups. Isotopic enrichment of the 70 Ge and the 74 Ge crystals is 96.3% and 96.8%, respectively. The residual chemical impurities present in both crystals were identified as phosphorus, copper, aluminum, and indium. A wide variety of experiments which take advantage of the isotopic purity of our crystals are discussed

  7. Molecules for materials: germanium hydride neutrals and anions. Molecular structures, electron affinities, and thermochemistry of GeHn/GeHn- (n = 0-4) and Ge2Hn/Ge2Hn(-) (n = 0-6).

    Science.gov (United States)

    Li, Qian-Shu; Lü, Rui-Hua; Xie, Yaoming; Schaefer, Henry F

    2002-12-01

    The GeH(n) (n = 0-4) and Ge(2)H(n) (n = 0-6) systems have been studied systematically by five different density functional methods. The basis sets employed are of double-zeta plus polarization quality with additional s- and p-type diffuse functions, labeled DZP++. For each compound plausible energetically low-lying structures were optimized. The methods used have been calibrated against a comprehensive tabulation of experimental electron affinities (Chemical Reviews 102, 231, 2002). The geometries predicted in this work include yet unknown anionic species, such as Ge(2)H(-), Ge(2)H(2)(-), Ge(2)H(3)(-), Ge(2)H(4)(-), and Ge(2)H(5)(-). In general, the BHLYP method predicts the geometries closest to the few available experimental structures. A number of structures rather different from the analogous well-characterized hydrocarbon radicals and anions are predicted. For example, a vinylidene-like GeGeH(2) (-) structure is the global minimum of Ge(2)H(2) (-). For neutral Ge(2)H(4), a methylcarbene-like HGë-GeH(3) is neally degenerate with the trans-bent H(2)Ge=GeH(2) structure. For the Ge(2)H(4) (-) anion, the methylcarbene-like system is the global minimum. The three different neutral-anion energy differences reported in this research are: the adiabatic electron affinity (EA(ad)), the vertical electron affinity (EA(vert)), and the vertical detachment energy (VDE). For this family of molecules the B3LYP method appears to predict the most reliable electron affinities. The adiabatic electron affinities after the ZPVE correction are predicted to be 2.02 (Ge(2)), 2.05 (Ge(2)H), 1.25 (Ge(2)H(2)), 2.09 (Ge(2)H(3)), 1.71 (Ge(2)H(4)), 2.17 (Ge(2)H(5)), and -0.02 (Ge(2)H(6)) eV. We also reported the dissociation energies for the GeH(n) (n = 1-4) and Ge(2)H(n) (n = 1-6) systems, as well as those for their anionic counterparts. Our theoretical predictions provide strong motivation for the further experimental study of these important germanium hydrides. Copyright 2002 Wiley

  8. Angular distributions of 250 GeV/c positive particles axially channeled in germanium crystal. Pt. 3

    International Nuclear Information System (INIS)

    Sun, C.R.; Gibson, W.M.; Kim, I.J.; Williams, G.O.; Carrigan, R.A. Jr.; Chrisman, B.L.; Toohig, T.E.; Guzik, Z.; Nigmanov, T.S.; Tsyganov, A.S.

    1982-01-01

    Channeling phenomena are observed for charged particles of momentum up to 250 GeV/c in a germanium crystal. The angular distributions of the channeled particles are compared with theoretical predictions based on a diffusion model. The results indicate additional mechanisms leading to dechanneling of the particles although channeling effects are observed for particles incident at up to several times the critical angle, in contrast with the results from low energy channeling. (orig.)

  9. The large enriched germanium experiment for neutrinoless double beta decay (LEGEND)

    Science.gov (United States)

    Abgrall, N.; Abramov, A.; Abrosimov, N.; Abt, I.; Agostini, M.; Agartioglu, M.; Ajjaq, A.; Alvis, S. I.; Avignone, F. T.; Bai, X.; Balata, M.; Barabanov, I.; Barabash, A. S.; Barton, P. J.; Baudis, L.; Bezrukov, L.; Bode, T.; Bolozdynya, A.; Borowicz, D.; Boston, A.; Boston, H.; Boyd, S. T. P.; Breier, R.; Brudanin, V.; Brugnera, R.; Busch, M.; Buuck, M.; Caldwell, A.; Caldwell, T. S.; Camellato, T.; Carpenter, M.; Cattadori, C.; Cederkäll, J.; Chan, Y.-D.; Chen, S.; Chernogorov, A.; Christofferson, C. D.; Chu, P.-H.; Cooper, R. J.; Cuesta, C.; Demidova, E. V.; Deng, Z.; Deniz, M.; Detwiler, J. A.; Di Marco, N.; Domula, A.; Du, Q.; Efremenko, Yu.; Egorov, V.; Elliott, S. R.; Fields, D.; Fischer, F.; Galindo-Uribarri, A.; Gangapshev, A.; Garfagnini, A.; Gilliss, T.; Giordano, M.; Giovanetti, G. K.; Gold, M.; Golubev, P.; Gooch, C.; Grabmayr, P.; Green, M. P.; Gruszko, J.; Guinn, I. S.; Guiseppe, V. E.; Gurentsov, V.; Gurov, Y.; Gusev, K.; Hakenmüeller, J.; Harkness-Brennan, L.; Harvey, Z. R.; Haufe, C. R.; Hauertmann, L.; Heglund, D.; Hehn, L.; Heinz, A.; Hiller, R.; Hinton, J.; Hodak, R.; Hofmann, W.; Howard, S.; Howe, M. A.; Hult, M.; Inzhechik, L. V.; Csáthy, J. Janicskó; Janssens, R.; Ješkovský, M.; Jochum, J.; Johansson, H. T.; Judson, D.; Junker, M.; Kaizer, J.; Kang, K.; Kazalov, V.; Kermadic, Y.; Kiessling, F.; Kirsch, A.; Kish, A.; Klimenko, A.; Knöpfle, K. T.; Kochetov, O.; Konovalov, S. I.; Kontul, I.; Kornoukhov, V. N.; Kraetzschmar, T.; Kröninger, K.; Kumar, A.; Kuzminov, V. V.; Lang, K.; Laubenstein, M.; Lazzaro, A.; Li, Y. L.; Li, Y.-Y.; Li, H. B.; Lin, S. T.; Lindner, M.; Lippi, I.; Liu, S. K.; Liu, X.; Liu, J.; Loomba, D.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Ma, H.; Majorovits, B.; Mamedov, F.; Martin, R. D.; Massarczyk, R.; Matthews, J. A. J.; McFadden, N.; Mei, D.-M.; Mei, H.; Meijer, S. J.; Mengoni, D.; Mertens, S.; Miller, W.; Miloradovic, M.; Mingazheva, R.; Misiaszek, M.; Moseev, P.; Myslik, J.; Nemchenok, I.; Nilsson, T.; Nolan, P.; O'Shaughnessy, C.; Othman, G.; Panas, K.; Pandola, L.; Papp, L.; Pelczar, K.; Peterson, D.; Pettus, W.; Poon, A. W. P.; Povinec, P. P.; Pullia, A.; Quintana, X. C.; Radford, D. C.; Rager, J.; Ransom, C.; Recchia, F.; Reine, A. L.; Riboldi, S.; Rielage, K.; Rozov, S.; Rouf, N. W.; Rukhadze, E.; Rumyantseva, N.; Saakyan, R.; Sala, E.; Salamida, F.; Sandukovsky, V.; Savard, G.; Schönert, S.; Schütz, A.-K.; Schulz, O.; Schuster, M.; Schwingenheuer, B.; Selivanenko, O.; Sevda, B.; Shanks, B.; Shevchik, E.; Shirchenko, M.; Simkovic, F.; Singh, L.; Singh, V.; Skorokhvatov, M.; Smolek, K.; Smolnikov, A.; Sonay, A.; Spavorova, M.; Stekl, I.; Stukov, D.; Tedeschi, D.; Thompson, J.; Van Wechel, T.; Varner, R. L.; Vasenko, A. A.; Vasilyev, S.; Veresnikova, A.; Vetter, K.; von Sturm, K.; Vorren, K.; Wagner, M.; Wang, G.-J.; Waters, D.; Wei, W.-Z.; Wester, T.; White, B. R.; Wiesinger, C.; Wilkerson, J. F.; Willers, M.; Wiseman, C.; Wojcik, M.; Wong, H. T.; Wyenberg, J.; Xu, W.; Yakushev, E.; Yang, G.; Yu, C.-H.; Yue, Q.; Yumatov, V.; Zeman, J.; Zeng, Z.; Zhitnikov, I.; Zhu, B.; Zinatulina, D.; Zschocke, A.; Zsigmond, A. J.; Zuber, K.; Zuzel, G.

    2017-10-01

    The observation of neutrinoless double-beta decay (0νββ) would show that lepton number is violated, reveal that neu-trinos are Majorana particles, and provide information on neutrino mass. A discovery-capable experiment covering the inverted ordering region, with effective Majorana neutrino masses of 15 - 50 meV, will require a tonne-scale experiment with excellent energy resolution and extremely low backgrounds, at the level of ˜0.1 count /(FWHM.t.yr) in the region of the signal. The current generation 76Ge experiments GERDA and the Majorana Demonstrator, utilizing high purity Germanium detectors with an intrinsic energy resolution of 0.12%, have achieved the lowest backgrounds by over an order of magnitude in the 0νββ signal region of all 0νββ experiments. Building on this success, the LEGEND collaboration has been formed to pursue a tonne-scale 76Ge experiment. The collaboration aims to develop a phased 0νββ experimental program with discovery potential at a half-life approaching or at 1028 years, using existing resources as appropriate to expedite physics results.

  10. Evaluation of the effects of dietary organic germanium, ge-132, and raffinose supplementation on caecal flora in rats.

    Science.gov (United States)

    Nakamura, Takashi; Nagura, Taizo; Sato, Katsuyuki; Ohnishi, Masao

    2012-01-01

    Poly-trans-[(2-carboxyethyl) germasesquioxane] (Ge-132) is the most common organic germanium compound. The ingestion of Ge-132 promotes bile secretion. We assessed the rat caecal characteristics after the administration of Ge-132 and raffinose, a prebiotic oligosaccharide, because both Ge-132 and some prebiotics can change the fecal color to yellow. We also compared the changes in the caecal flora caused by the two compounds. In addition, we evaluated the simultaneous administration of Ge-132 and raffinose and their effects on β-glucuronidase activity, which is known to be a factor related to colon cancer. Male Wistar rats (three weeks old) were given one of the following diets: 1) a control diet (control group), 2) a diet containing 0.05% Ge-132 (Ge-132 group), 3) a diet containing 5% raffinose (RAF group) or 4) a diet containing 0.05% Ge-132 + 5% raffinose (GeRAF group). The Bifidobacterium, Lactobacillus and total bacteria counts were significantly increased by the dietary raffinose, and Ge-132 did not suppress this increase. The raffinose intake increased caecal acetic acid production significantly. The activity of β-glucuronidase in the caecal contents was increased by dietary Ge-132, whereas dietary raffinose decreased the β-glucuronidase activity significantly. These results indicate that the simultaneous intake of dietary raffinose and Ge-132 does not inhibit the effects of either compound on intestinal fermentation and bile secretion. Additionally, the simultaneous intake of both raffinose and Ge-132 could abrogate the increase in β-glucuronidase activity induced by Ge-132 alone.

  11. Germanium diffusion with vapor-phase GeAs and oxygen co-incorporation in GaAs

    Science.gov (United States)

    Wang, Wei-Fu; Cheng, Kai-Yuan; Hsieh, Kuang-Chien

    2018-01-01

    Vapor-phase germanium diffusion has been demonstrated in Zn-doped and semi-insulating GaAs in sealed ampoules with GeAs powders and excess arsenic. Secondary-ion-mass spectroscopy (SIMS) profiles indicate the presence of unintentional co-incorporation of oxygen in high densities (>1017/cm3) along with diffused germanium donors whose concentration (>>1018/cm3) determined by electro-chemical capacitance-voltage (ECV) profiler shows significant compensation near the surface. The source of oxygen mainly originates from the GeAs powder which contains Ge-O surface oxides. Variable-temperature photoluminescence (PL) shows that in GeAs-diffused samples, a broad peak ranging from 0.86-1.38 eV with the peak position around 1.1 eV predominates at low temperatures while the near band-edge luminescence quenches. The broad band is attributed to the GeGa-VGa self-activated (SA) centers possibly associated with nearby oxygen-related defect complex, and its luminescence persists up to 400 K. The configurational-coordinate modeling finds that the SA defect complex has a thermal activation energy of 150-180 meV and a vibrational energy 26.8 meV. The presence of oxygen does not much affect the SA emission intensity but may have influenced the peak position, vibration frequency and activation energy as compared to other common donor-VGa defects in GaAs.

  12. Germanium diffusion with vapor-phase GeAs and oxygen co-incorporation in GaAs

    Directory of Open Access Journals (Sweden)

    Wei-Fu Wang

    2018-01-01

    Full Text Available Vapor-phase germanium diffusion has been demonstrated in Zn-doped and semi-insulating GaAs in sealed ampoules with GeAs powders and excess arsenic. Secondary-ion-mass spectroscopy (SIMS profiles indicate the presence of unintentional co-incorporation of oxygen in high densities (>1017/cm3 along with diffused germanium donors whose concentration (>>1018/cm3 determined by electro-chemical capacitance-voltage (ECV profiler shows significant compensation near the surface. The source of oxygen mainly originates from the GeAs powder which contains Ge-O surface oxides. Variable-temperature photoluminescence (PL shows that in GeAs-diffused samples, a broad peak ranging from 0.86-1.38 eV with the peak position around 1.1 eV predominates at low temperatures while the near band-edge luminescence quenches. The broad band is attributed to the GeGa-VGa self-activated (SA centers possibly associated with nearby oxygen-related defect complex, and its luminescence persists up to 400 K. The configurational-coordinate modeling finds that the SA defect complex has a thermal activation energy of 150-180 meV and a vibrational energy 26.8 meV. The presence of oxygen does not much affect the SA emission intensity but may have influenced the peak position, vibration frequency and activation energy as compared to other common donor-VGa defects in GaAs.

  13. Search for neutrinoless double beta decay of Ge-76 with the GERmanium Detector Array '' GERDA ''

    International Nuclear Information System (INIS)

    Brugnera, R.

    2009-01-01

    The study of neutrinoless double beta decay (DBD) is the most powerful approach to the fundamental question if the neutrino is a Majorana particle, i.e. its own anti-particle. The observation of neutrinoless DBD would not only establish the Majorana nature of the neutrino but also represent a determination of its effective mass if the nuclear matrix element is given. So far, the most sensitive results have been obtained with Ge-76, and the group of Klapdor-Kleingrothaus has made a claim of discovery. Future experiments have to reduce radioactive backgrounds to increase the sensitivity. '' GERDA '' is a new double beta-decay experiment which is currently under construction in the INFN Gran Sasso National Laboratory, Italy. It is implementing a new shielding concept by operating bare Ge diodes - enriched in Ge-76 - in high purity liquid argon supplemented by a water shield. The aim of '' GERDA '' is to verify or refute the recent claim of discovery, and, in a second phase, to achieve a two orders of magnitude lower background index than recent experiments, increasing the sensitive mass and reaching exposure of 100 kg yr. It be will discuss design, physics reach, and status of construction of '' GERDA '', and present results from various R efforts including long term stability of bare Ge diodes in cryogenic liquids, material screening, cryostat performance, detector segmentation, cryogenic precision electronics, safety aspects, and Monte Carlo simulations. (author)

  14. Germanium geochemistry and mineralogy

    Science.gov (United States)

    Bernstein, L.R.

    1985-01-01

    Germanium is enriched in the following geologic environments: 1. (1) iron meteorites and terrestrial iron-nickel; 2. (2) sulfide ore deposits, particularly those hosted by sedimentary rocks; 3. (3) iron oxide deposits; 4. (4) oxidized zones of Ge-bearing sulfide deposits; 5. (5) pegmatites, greisens, and skarns; and 6. (6) coal and lignitized wood. In silicate melts, Ge is highly siderophile in the presence of native iron-nickel; otherwise, it is highly lithophile. Among silicate minerals, Ge is concentrated in those having less polymerized silicate tetrahedra such as olivine and topaz. In deposits formed from hydrothermal solutions, Ge tends to be enriched mostly in either sulfides or in fluorine-bearing phases; it is thus concentrated both in some hydrothermal sulfide deposits and in pegmatites, greisens, and skarns. In sulfide deposits that formed from solutions having low to moderate sulfur activity, Ge is concentrated in sphalerite in amounts up to 3000 ppm. Sulfide deposits that formed from solutions having higher sulfur activity allowed Ge to either form its own sulfides, particularly with Cu, or to substitute for As, Sn, or other metals in sulfosalts. The Ge in hydrothermal fluids probably derives from enrichment during the fractional crystallization of igneous fluids, or is due to the incorporation of Ge from the country rocks, particularly from those containing organic material. Germanium bonds to lignin-derivative organic compounds that are found in peat and lignite, accounting for its common concentration in coals and related organic material. Germanium is precipitated from water together with iron hydroxide, accounting for its concentration in some sedimentary and supergene iron oxide deposits. It also is able to substitute for Fe in magnetite in a variety of geologic environments. In the oxidized zone of Ge-bearing sulfide deposits, Ge is concentrated in oxides, hydroxides, and hydroxy-sulfates, sometimes forming its own minerals. It is particularly

  15. Direct band gap light emission and detection at room temperature in bulk germanium diodes with HfGe/Ge/TiN structure

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dong, E-mail: wang.dong.539@m.kyushu-u.ac.jp [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Maekura, Takayuki [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Yamamoto, Keisuke; Nakashima, Hiroshi [Art, Science and Technology Center for Cooperative Research, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan)

    2016-03-01

    Direct band gap (DBG) electroluminescence (EL) and photo detection were studied at room temperature for n-type bulk germanium (Ge) diodes with a fin type lateral HfGe/Ge/TiN structure. DBG EL spectra peaked at 1.55 μm were clearly observed due to small hole and electron barrier heights of HfGe/Ge and TiN/Ge contacts. DBG EL peak intensity increased with increasing doping level of Ge substrate due to increased electron population in direct conduction band. The integrated intensity of DBG EL spectrum is proportional to the area of active region, implying a good surface-uniformity of EL efficiency. Small dark current intensity was measured as 2.4 × 10{sup −7} A under a reverse bias voltage of − 1 V, corresponding to dark current densities of 5.3 × 10{sup −10} A/μm or 3.2 × 10{sup −10} A/μm{sup 2}. At the wavelength of 1.55 μm, a linear dependence of photo current intensity on laser power was observed with a responsivity of 0.44 A/W at a reverse bias voltage of − 1 V. - Highlights: • Lateral HfGe/Ge/TiN diodes were fabricated on bulk Ge substrates. • The highest temperature was 400 °C for the entire fabrication process. • Electroluminescence spectra were measured for HfGe/Ge/TiN diodes with different parameters. • Dark current densities were 5.3 × 10{sup −10} A/μm or 3.2 × 10{sup −10} A/μm{sup 2} at − 1 V. • Responsivity was 0.44 A/W, corresponding to an external quantum efficiency of 35.2%.

  16. Application of the A/E pulse shape discrimination method to first Ge-76 enriched BEGe detectors operated in GERDA

    Energy Technology Data Exchange (ETDEWEB)

    Lazzaro, Andrea; Agostini, Matteo; Budjas, Dusan; Schoenert, Stefan [Physik-Department E15, Technische Universitaet Muenchen (Germany); Collaboration: GERDA-Collaboration

    2013-07-01

    In 2013 the Gerda experiment will be upgraded to its second phase with more than double of the current {sup 76}Ge mass. The additional diodes are custom made Broad Energy Germanium (BEGe) detectors. This design has been chosen to enhance the pulse shape discrimination (PSD) capability, with respect to the Phase I coaxial detectors. The goal of Phase II is to improve by one order of magnitude the current background index; the PSD will bring a major contribution to this result. Since summer 2012 the first set of five enriched BEGe detectors are operated in Gerda Phase I. This offers us the possibility to test the PSD performances and the signal analysis in an environment as close as possible to the Gerda Phase II configuration. In this talk I present the A/E analysis, the calibration of the cut parameters and the results in terms of background reduction for the data taken with these enriched BEGe.

  17. Optical properties and thermal stability of germanium oxide (GeO2) nanocrystals with α-quartz structure

    International Nuclear Information System (INIS)

    Ramana, C.V.; Carbajal-Franco, G.; Vemuri, R.S.; Troitskaia, I.B.; Gromilov, S.A.; Atuchin, V.V.

    2010-01-01

    Germanium dioxide (GeO 2 ) crystals were prepared by a chemical precipitation method at a relatively low-temperature (100 o C). The grown crystals were characterized by studying their microstructure, optical properties and thermal stability. The results indicate that the grown GeO 2 crystals exhibit α-quartz type crystal structure. The lattice parameters obtained from XRD were a = 4.987(4) A and c = 5.652(5) A. Electron microscopy analysis indicates a high structural quality of GeO 2 crystals grown using the present approach. Optical absorption measurements indicate a direct bandgap of 5.72 eV without any additional bands arising from localized or defect states. Thermogravimetric measurements indicate the temperature stability of the grown GeO 2 nanocrystals. Microscopic analysis coupled with energy dispersive X-ray spectroscopy of the GeO 2 crystals with α-quartz type crystal structure indicates their stability in chemical composition up to a temperature of 400 deg. C. The surface morphology of GeO 2 crystals, however, found to be changing with the increase in temperature.

  18. Autoionizing energy levels and extended spectral analysis of copper-like gallium and germanium (Ga III, Ge IV)

    International Nuclear Information System (INIS)

    Ryabtsev, A.N.; Wyart, J.F.

    1987-01-01

    The spark spectra of doubly ionized gallium and triply ionized germanium have been observed. Lines broadened by autoionization have been attributed to 3d 9 4p 2 - 3d 10 4p transitions on the basis of parametric studies of the configurations 3d 9 4p 2 + 3d 9 4s4d. Line strengths and autoionization widths support the identifications. The analysis of the 3d 10 nl system has been corrected and extended. The ionization energy of Ge IV is 368 720 cm -1 ± 10 cm -1 . (orig.)

  19. Germanium content and base doping level influence on extrinsic base resistance and dynamic performances of SiGe:C heterojunction bipolar transistors

    International Nuclear Information System (INIS)

    Ramirez-Garcia, E; Valdez-Monroy, L A; Rodriguez-Mendez, L M; Valdez-Perez, D; Galaz-Larios, M C; Enciso-Aguilar, M A; Zerounian, N; Aniel, F

    2014-01-01

    We describe a reliable technique to separate the different contributions to the apparent base resistance (R B  = R Bx  + X R Bi ) of silicon germanium carbon (SiGe:C) heterojunction bipolar transistors (HBTs). The extrinsic base resistance (R Bx ) is quantified using small-signal measurements. The base-collector junction distribution factor (X) and the intrinsic base resistance (R Bi ) are extracted from high frequency noise (MWN) measurements. This method is applied to five different SiGe:C HBTs varying in base doping level and germanium content. The results show that high doping levels improve high frequency noise performances while germanium gradient helps to maintain outstanding dynamic performances. This method could be used to elucidate the base technological configuration that ensures low noise together with remarkable dynamic performances in state-of-the-art SiGe:C HBTs. (paper)

  20. New quaternary thallium indium germanium selenide TlInGe2Se6: Crystal and electronic structure

    Science.gov (United States)

    Khyzhun, O. Y.; Parasyuk, O. V.; Tsisar, O. V.; Piskach, L. V.; Myronchuk, G. L.; Levytskyy, V. O.; Babizhetskyy, V. S.

    2017-10-01

    Crystal structure of a novel quaternary thallium indium germanium selenide TlInGe2Se6 was investigated by means of powder X-ray diffraction method. It was determined that the compound crystallizes in the trigonal space group R3 with the unit cell parameters a = 10.1798(2) Å, c = 9.2872(3) Å. The relationship with similar structures was discussed. The as-synthesized TlInGe2Se6 ingot was tested with X-ray photoelectron spectroscopy (XPS) and X-ray emission spectroscopy (XES). In particular, the XPS valence-band and core-level spectra were recorded for initial and Ar+ ion-bombarded surfaces of the sample under consideration. The XPS data allow for statement that the TlInGe2Se6 surface is rigid with respect to Ar+ ion-bombardment. Particularly, Ar+ ion-bombardment (3.0 keV, 5 min duration, ion current density fixed at 14 μA/cm2) did not cause substantial modifications of stoichiometry in topmost surface layers. Furthermore, comparison on a common energy scale of the XES Se Kβ2 and Ge Kβ2 bands and the XPS valence-band spectrum reveals that the principal contributions of the Se 4p and Ge 4p states occur in the upper and central portions of the valence band of TlInGe2Se6, respectively, with also their substantial contributions in other portions of the band. The bandgap energy of TlInGe2Se6 at the level of αg=103 cm-1 is equal to 2.38 eV at room temperature.

  1. Kinetics of plasma oxidation of germanium-tin (GeSn)

    Science.gov (United States)

    Wang, Wei; Lei, Dian; Dong, Yuan; Zhang, Zheng; Pan, Jisheng; Gong, Xiao; Tok, Eng-Soon; Yeo, Yee-Chia

    2017-12-01

    The kinetics of plasma oxidation of GeSn at low temperature is investigated. The oxidation process is described by a power-law model where the oxidation rate decreases rapidly from the initial oxidation rate with increasing time. The oxidation rate of GeSn is higher than that of pure Ge, which can be explained by the higher chemical reaction rate at the GeSn-oxide/GeSn interface. In addition, the Sn atoms at the interface region exchange positions with the underlying Ge atoms during oxidation, leading to a SnO2-rich oxide near the interface. The bandgap of GeSn oxide is extracted to be 5.1 ± 0.2 eV by XPS, and the valence band offset at the GeSn-oxide/GeSn heterojunction is found to be 3.7 ± 0.2 eV. Controlled annealing experiments demonstrate that the GeSn oxide is stable with respect to annealing temperatures up to 400 °C. However, after annealing at 450 °C, the GeO2 is converted to GeO, and desorbs from the GeSn-oxide/GeSn, leaving behind Sn oxide.

  2. Structural properties of relaxed thin film germanium layers grown by low temperature RF-PECVD epitaxy on Si and Ge (100) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Cariou, R., E-mail: romain.cariou@polytechnique.edu [LPICM-CNRS, Ecole Polytechnique, 91128, Palaiseau (France); III-V lab a joint laboratory between Alcatel-Lucent Bell Labs France, Thales Research and Technology and CEA-LETI, route de Nozay, 91460, Marcoussis, France. (France); Ruggeri, R. [LPICM-CNRS, Ecole Polytechnique, 91128, Palaiseau (France); CNR-IMM, strada VIII n°5, zona industriale, 95121, Catania (Italy); Tan, X.; Nassar, J.; Roca i Cabarrocas, P. [LPICM-CNRS, Ecole Polytechnique, 91128, Palaiseau (France); Mannino, Giovanni [CNR-IMM, strada VIII n°5, zona industriale, 95121, Catania (Italy)

    2014-07-15

    We report on unusual low temperature (175 °C) heteroepitaxial growth of germanium thin films using a standard radio-frequency plasma process. Spectroscopic ellipsometry and transmission electron microscopy (TEM) reveal a perfect crystalline quality of epitaxial germanium layers on (100) c-Ge wafers. In addition direct germanium crystal growth is achieved on (100) c-Si, despite 4.2% lattice mismatch. Defects rising from Ge/Si interface are mostly located within the first tens of nanometers, and threading dislocation density (TDD) values as low as 10{sup 6} cm{sup −2} are obtained. Misfit stress is released fast: residual strain of −0.4% is calculated from Moiré pattern analysis. Moreover we demonstrate a striking feature of low temperature plasma epitaxy, namely the fact that crystalline quality improves with thickness without epitaxy breakdown, as shown by TEM and depth profiling of surface TDD.

  3. Bimodal height distribution of self-assembled germanium islands grown on Si0.84Ge0.16 pseudo-substrates

    DEFF Research Database (Denmark)

    Pedersen, Erik Vesterlund; Jensen, Flemming; Shiryaev, Sergey Y.

    1998-01-01

    We have investigated the size distribution of germanium islands deposited onto a Si0.84Ge0.16 buffer layer, by atomic force microscopy. The size distribution was found to be bimodal at 630-740 degrees C and consisted of one group of smaller 'pyramidal' islands with a broad distribution of diameters...

  4. MOVPE growth and characterization of heteroepitaxial germanium on silicon using iBuGe as precursor

    Energy Technology Data Exchange (ETDEWEB)

    Attolini, G. [IMEM-CNR, Parco Area delle Scienze, 37 A, 43124 Parma (Italy); Ponraj, J.S. [University of Information Science and Technology, St Paul the Apostle, Ohrid 6000 (Macedonia, The Former Yugoslav Republic of); Frigeri, C.; Buffagni, E.; Ferrari, C. [IMEM-CNR, Parco Area delle Scienze, 37 A, 43124 Parma (Italy); Musayeva, N.; Jabbarov, R. [Research and Development Center for Hi-Technologies, MCIT, Inshaatchilar ave., 2, AZ1073, Baku (Azerbaijan); Institute of Physics, ANAS, H. Javid ave., 33, AZ1143, Baku (Azerbaijan); Bosi, M., E-mail: bosi@imem.cnr.it [IMEM-CNR, Parco Area delle Scienze, 37 A, 43124 Parma (Italy)

    2016-01-01

    Graphical abstract: - Highlights: • Germanium layer were deposited on silicon substrates. • A novel metal organic precursor (isobutyl germane) was used. • MOVPE growth process was optimized. • Layers were characterized by TEM, XRD; SEM and AFM. - Abstract: Being an attractive and demanding candidate in the field of energy conversion, germanium has attained widespread applications. The present work is aimed at the study of metal organic vapour phase epitaxy of germanium thin films on (0 0 1) silicon at different growth temperatures using isobutyl germane as a precursor. The epilayers were characterized by X-ray diffraction, high resolution transmission electron microscopy, atomic force microscopy and scanning electron microscopy in order to understand the structural and morphological properties. The films were found to be epitaxially grown and single crystalline with slight misorientation (below 0.1 degrees). The interface between the film and substrate was analyzed in depth and different temperature dependent growth behaviours were evidenced. The major relevant lattice imperfections observed were attributed to planar defects and threading dislocations.

  5. Insights into thermal diffusion of germanium and oxygen atoms in HfO2/GeO2/Ge gate stacks and their suppressed reaction with atomically thin AlOx interlayers

    International Nuclear Information System (INIS)

    Ogawa, Shingo; Asahara, Ryohei; Minoura, Yuya; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji; Sako, Hideki; Kawasaki, Naohiko; Yamada, Ichiko; Miyamoto, Takashi

    2015-01-01

    The thermal diffusion of germanium and oxygen atoms in HfO 2 /GeO 2 /Ge gate stacks was comprehensively evaluated by x-ray photoelectron spectroscopy and secondary ion mass spectrometry combined with an isotopic labeling technique. It was found that 18 O-tracers composing the GeO 2 underlayers diffuse within the HfO 2 overlayers based on Fick's law with the low activation energy of about 0.5 eV. Although out-diffusion of the germanium atoms through HfO 2 also proceeded at the low temperatures of around 200 °C, the diffusing germanium atoms preferentially segregated on the HfO 2 surfaces, and the reaction was further enhanced at high temperatures with the assistance of GeO desorption. A technique to insert atomically thin AlO x interlayers between the HfO 2 and GeO 2 layers was proven to effectively suppress both of these independent germanium and oxygen intermixing reactions in the gate stacks

  6. Insights into thermal diffusion of germanium and oxygen atoms in HfO{sub 2}/GeO{sub 2}/Ge gate stacks and their suppressed reaction with atomically thin AlO{sub x} interlayers

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Shingo, E-mail: Shingo-Ogawa@trc.toray.co.jp [Toray Research Center, Inc., 3-3-7 Sonoyama, Otsu, Shiga 520-8567 (Japan); Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Asahara, Ryohei; Minoura, Yuya; Hosoi, Takuji, E-mail: hosoi@mls.eng.osaka-u.ac.jp; Shimura, Takayoshi; Watanabe, Heiji [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Sako, Hideki; Kawasaki, Naohiko; Yamada, Ichiko; Miyamoto, Takashi [Toray Research Center, Inc., 3-3-7 Sonoyama, Otsu, Shiga 520-8567 (Japan)

    2015-12-21

    The thermal diffusion of germanium and oxygen atoms in HfO{sub 2}/GeO{sub 2}/Ge gate stacks was comprehensively evaluated by x-ray photoelectron spectroscopy and secondary ion mass spectrometry combined with an isotopic labeling technique. It was found that {sup 18}O-tracers composing the GeO{sub 2} underlayers diffuse within the HfO{sub 2} overlayers based on Fick's law with the low activation energy of about 0.5 eV. Although out-diffusion of the germanium atoms through HfO{sub 2} also proceeded at the low temperatures of around 200 °C, the diffusing germanium atoms preferentially segregated on the HfO{sub 2} surfaces, and the reaction was further enhanced at high temperatures with the assistance of GeO desorption. A technique to insert atomically thin AlO{sub x} interlayers between the HfO{sub 2} and GeO{sub 2} layers was proven to effectively suppress both of these independent germanium and oxygen intermixing reactions in the gate stacks.

  7. Impacts of doping on epitaxial germanium thin film quality and Si-Ge interdiffusion

    KAUST Repository

    Zhou, Guangnan

    2018-04-03

    Ge-on-Si structures with three different dopants (P, As and B) and those without intentional doping were grown, annealed and characterized by several different material characterization methods. All samples have a smooth surface (roughness < 1.5 nm), and the Ge films are almost entirely relaxed. B doped Ge films have threading dislocations above 1 × 10 cm, while P and As doping can reduce the threading dislocation density to be less than 10 cm without annealing. The interdiffusion of Si and Ge of different films have been investigated experimentally and theoretically. A quantitative model of Si-Ge interdiffusion under extrinsic conditions across the full x range was established including the dislocationmediated diffusion. The Kirkendall effect has been observed. The results are of technical significance for the structure, doping, and process design of Ge-on-Si based devices, especially for photonic applications.

  8. Impacts of doping on epitaxial germanium thin film quality and Si-Ge interdiffusion

    KAUST Repository

    Zhou, Guangnan; Lee, Kwang Hong; Anjum, Dalaver H.; Zhang, Qiang; Zhang, Xixiang; Tan, Chuan Seng; Xia, Guangrui

    2018-01-01

    Ge-on-Si structures with three different dopants (P, As and B) and those without intentional doping were grown, annealed and characterized by several different material characterization methods. All samples have a smooth surface (roughness < 1.5 nm), and the Ge films are almost entirely relaxed. B doped Ge films have threading dislocations above 1 × 10 cm, while P and As doping can reduce the threading dislocation density to be less than 10 cm without annealing. The interdiffusion of Si and Ge of different films have been investigated experimentally and theoretically. A quantitative model of Si-Ge interdiffusion under extrinsic conditions across the full x range was established including the dislocationmediated diffusion. The Kirkendall effect has been observed. The results are of technical significance for the structure, doping, and process design of Ge-on-Si based devices, especially for photonic applications.

  9. Molecular precursors for the phase-change material germanium-antimony-telluride, Ge{sub 2}Sb{sub 2}Te{sub 5} (GST)

    Energy Technology Data Exchange (ETDEWEB)

    Harmgarth, Nicole; Zoerner, Florian; Engelhardt, Felix; Edelmann, Frank T. [Chemisches Institut, Otto-von-Guericke-Universitaet Magdeburg (Germany); Liebing, Phil [Laboratorium fuer Anorganische Chemie, ETH Zuerich (Switzerland); Burte, Edmund P.; Silinskas, Mindaugas [Institut fuer Mikro- und Sensorsysteme, Otto-von-Guericke-Universitaet Magdeburg (Germany)

    2017-10-04

    This review provides an overview of the precursor chemistry that has been developed around the phase-change material germanium-antimony-telluride, Ge{sub 2}Sb{sub 2}Te{sub 5} (GST). Thin films of GST can be deposited by employing either chemical vapor deposition (CVD) or atomic layer deposition (ALD) techniques. In both cases, the success of the layer deposition crucially depends on the proper choice of suitable molecular precursors. Previously reported processes mainly relied on simple alkoxides, alkyls, amides and halides of germanium, antimony, and tellurium. More sophisticated precursor design provided a number of promising new aziridinides and guanidinates. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. N-Heterocyclic Carbene Coinage Metal Complexes of the Germanium-Rich Metalloid Clusters [Ge9R3]− and [Ge9RI2]2− with R = Si(iPr3 and RI = Si(TMS3

    Directory of Open Access Journals (Sweden)

    Felix S. Geitner

    2017-07-01

    Full Text Available We report on the synthesis of novel coinage metal NHC (N-heterocyclic carbene compounds of the germanium-rich metalloid clusters [Ge9R3]− and [Ge9RI2]2− with R = Si(iPr3 and RI = Si(TMS3. NHCDippCu{η3Ge9R3} with R = Si(iPr3 (1 represents a less bulky silyl group-substituted derivative of the known analogous compounds with R = Si(iBu3 or Si(TMS3. The coordination of the [NHCDippCu]+ moiety to the cluster unit occurs via one triangular face of the tri-capped trigonal prismatic [Ge9] cluster. Furthermore, a series of novel Zintl cluster coinage metal NHC compounds of the type (NHCM2{η3Ge9RI2} (RI = Si(TMS3 M = Cu, Ag and Au; NHC = NHCDipp or NHCMes is presented. These novel compounds represent a new class of neutral dinuclear Zintl cluster coinage metal NHC compounds, which are obtained either by the stepwise reaction of a suspension of K12Ge17 with Si(TMS3Cl and the coinage metal carbene complexes NHCMCl (M = Cu, Ag, Au, or via a homogenous reaction using the preformed bis-silylated cluster K2[Ge9(Si(TMS32] and the corresponding NHCMCl (M = Cu, Ag, Au complex. The molecular structures of NHCDippCu{η3Ge9(Si(iPr33} (1 and (NHCDippCu2{η3-Ge9(Si(TMS32} (2 were determined by single crystal X-ray diffraction methods. In 2, the coordination of the [NHCDippCu]+ moieties to the cluster unit takes place via both open triangular faces of the [Ge9] entity. Furthermore, all compounds were characterized by means of NMR spectroscopy (1H, 13C, 29Si and ESI-MS.

  11. Germanium recovery from gasification fly ash: evaluation of end-products obtained by precipitation methods.

    Science.gov (United States)

    Arroyo, Fátima; Font, Oriol; Fernández-Pereira, Constantino; Querol, Xavier; Juan, Roberto; Ruiz, Carmen; Coca, Pilar

    2009-08-15

    In this study the purity of the germanium end-products obtained by two different precipitation methods carried out on germanium-bearing solutions was evaluated as a last step of a hydrometallurgy process for the recovery of this valuable element from the Puertollano Integrated Gasification Combined Cycle (IGCC) fly ash. Since H(2)S is produced as a by-product in the gas cleaning system of the Puertollano IGCC plant, precipitation of germanium as GeS(2) was tested by sulfiding the Ge-bearing solutions. The technological and hazardous issues that surround H(2)S handling conducted to investigate a novel precipitation procedure: precipitation as an organic complex by adding 1,2-dihydroxy benzene pyrocatechol (CAT) and cetyltrimethylammonium bromide (CTAB) to the Ge-bearing solutions. Relatively high purity Ge end-products (90 and 93% hexagonal-GeO(2) purity, respectively) were obtained by precipitating Ge from enriched solutions, as GeS(2) sulfiding the solutions with H(2)S, or as organic complex with CAT/CTAB mixtures and subsequent roasting of the precipitates. Both methods showed high efficiency (>99%) to precipitate selectively Ge using a single precipitation stage from germanium-bearing solutions.

  12. Experience from operating germanium detectors in GERDA

    Science.gov (United States)

    Palioselitis, Dimitrios; GERDA Collaboration

    2015-05-01

    Phase I of the Germanium Detector Array (GERDA) experiment, searching for the neutrinoless double beta (0νββ) decay of 76Ge, was completed in September 2013. The most competitive half-life lower limit for the 0νββ decay of 76Ge was set (T-0ν1/2 > 2.1 · 1025 yr at 90% C.L.). GERDA operates bare Ge diodes immersed in liquid argon. During Phase I, mainly refurbished semi-coaxial high purity Ge detectors from previous experiments were used. The experience gained with handling and operating bare Ge diodes in liquid argon, as well as the stability and performance of the detectors during GERDA Phase I are presented. Thirty additional new enriched BEGe-type detectors were produced and will be used in Phase II. A subgroup of these detectors has already been used successfully in GERDA Phase I. The present paper gives an overview of the production chain of the new germanium detectors, the steps taken to minimise the exposure to cosmic radiation during manufacturing, and the first results of characterisation measurements in vacuum cryostats.

  13. Experience from operating germanium detectors in GERDA

    International Nuclear Information System (INIS)

    Palioselitis, Dimitrios

    2015-01-01

    Phase I of the Germanium Detector Array (GERDA) experiment, searching for the neutrinoless double beta (0νββ) decay of 76 Ge, was completed in September 2013. The most competitive half-life lower limit for the 0νββ decay of 76 Ge was set (T- 0ν 1/2 > 2.1 · 10 25 yr at 90% C.L.). GERDA operates bare Ge diodes immersed in liquid argon. During Phase I, mainly refurbished semi-coaxial high purity Ge detectors from previous experiments were used. The experience gained with handling and operating bare Ge diodes in liquid argon, as well as the stability and performance of the detectors during GERDA Phase I are presented. Thirty additional new enriched BEGe-type detectors were produced and will be used in Phase II. A subgroup of these detectors has already been used successfully in GERDA Phase I. The present paper gives an overview of the production chain of the new germanium detectors, the steps taken to minimise the exposure to cosmic radiation during manufacturing, and the first results of characterisation measurements in vacuum cryostats. (paper)

  14. Investigation of the operational quality of germanium gamma detectors. Estimation of Ge:Li detector survival rates

    International Nuclear Information System (INIS)

    Zerbib, J.-C.

    1980-01-01

    A working group has produced tables of information on gamma semiconductor Ge detectors: Ge(Li) or intrinsic Ge. The information was obtained as a result of enquirres addressed to various laboratories, and concerns 228-sources in France and Belgium [fr

  15. Photochemical process of divalent germanium responsible for photorefractive index change in GeO2-SiO2 glasses.

    Science.gov (United States)

    Sakoh, Akifumi; Takahashi, Masahide; Yoko, Toshinobu; Nishii, Junji; Nishiyama, Hiroaki; Miyamoto, Isamu

    2003-10-20

    The photoluminescence spectra of the divalent Ge (Ge2+) center in GeO2-SiO2 glasses with different photosensitivities were investigated by means of excitation-emission energy mapping. The ultraviolet light induced photorefractivity has been correlated with the local structure around the Ge2+ centers. The glasses with a larger photorefractivity tended to exhibit a greater band broadening of the singlet-singlet transition on the higher excitation energy side accompanied by an increase in the Stokes shifts. This strongly suggests the existence of highly photosensitive Ge2+ centers with higher excitation energies. It is also found that the introduction of a hydroxyl group or boron species in GeO2-SiO2 glasses under appropriate conditions modifies the local environment of Ge2+ leading to an enhanced photorefractivity.

  16. The MAJORANA DEMONSTRATOR: A Search for Neutrinoless Double-beta Decay of Germanium-76

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, Alexis G.; Aguayo, Estanislao; Avignone, F. T.; Zhang, C.; Back, Henning O.; Barabash, Alexander S.; Bergevin, M.; Bertrand, F.; Boswell, M.; Brudanin, V.; Busch, Matthew; Chan, Yuen-Dat; Christofferson, Cabot-Ann; Collar, J. I.; Combs, Dustin C.; Cooper, R. J.; Detwiler, Jason A.; Leon, Jonathan D.; Doe, Peter J.; Efremenko, Yuri; Egorov, Viatcheslav; Ejiri, H.; Elliott, S. R.; Esterline, James H.; Fast, James E.; Fields, N.; Finnerty, P.; Fraenkle, Florian; Gehman, Victor M.; Giovanetti, G. K.; Green, M.; Guiseppe, Vincente; Gusey, K.; Hallin, A. L.; Hazama, R.; Henning, Reyco; Hime, Andrew; Hoppe, Eric W.; Horton, Mark; Howard, Stanley; Howe, Mark; Johnson, R. A.; Keeter, K.; Keillor, Martin E.; Keller, C.; Kephart, Jeremy D.; Kidd, M. F.; Knecht, A.; Kochetov, Oleg; Konovalov, S.; Kouzes, Richard T.; LaFerriere, Brian D.; LaRoque, B. H.; Leviner, L.; Loach, J. C.; MacMullin, S.; Marino, Michael G.; Martin, R. D.; Mei, Dong-Ming; Merriman, Jason H.; Miller, M. L.; Mizouni, Leila; Nomachi, Masaharu; Orrell, John L.; Overman, Nicole R.; Phillips, D.; Poon, Alan; Perumpilly, Gopakumar; Prior, Gersende; Radford, D. C.; Rielage, Keith; Robertson, R. G. H.; Ronquest, M. C.; Shima, T.; Shirchenko, M.; Snavely, Kyle J.; Sobolev, V.; Steele, David; Strain, J.; Thomas, K.; Timkin, V.; Tornow, Werner; Vanyushin, I.; Varner, R. L.; Vetter, Kai; Vorren, Kris R.; Wilkerson, J. F.; Wolfe, B. A.; Yakushev, E.; Young, A.; Yu, Chang-Hong; Yumatov, Vladimir

    2012-09-28

    The observation of neutrinoless double-beta decay would determine whether the neutrino is a Majorana particle and provide information on the absolute scale of neutrino mass. The MAJORANA Collaboration is constructing the DEMONSTRATOR, an array of germanium detectors, to search for neutrinoless double-beta decay of 76Ge. The DEMONSTRATOR will contain 40 kg of germanium; up to 30 kg will be enriched to 86% in 76Ge. The DEMONSTRATOR will be deployed deep underground in an ultra-low-background shielded environment. Operation of the DEMONSTRATOR aims to determine whether a future tonne-scale germanium experiment can achieve a background goal of one count per tonne-year in a 4-keV region of interest around the 76Ge neutrinoless double-beta decay Q-value of 2039 keV.

  17. Effective mass approximation versus full atomistic model to calculate the output characteristics of a gate-all-around germanium nanowire field effect transistor (GAA-GeNW-FET)

    Science.gov (United States)

    Bayani, Amir Hossein; Voves, Jan; Dideban, Daryoosh

    2018-01-01

    Here, we compare the output characteristics of a gate-all-around germanium nanowire field effect transistor (GAA-GeNW-FET) with 2.36 nm2 square cross-section area using tight-binding (TB) sp3d5s∗ model (full atomistic model (FAM)) and effective mass approximation (EMA). Synopsys/QuantumWise Atomistix ToolKit (ATK) and Silvaco Atlas3D are used to consider the TB model and EMA, respectively. Results show that EMA predicted only one quantum state (QS) for quantum transport, whereas FAM predicted three QSs. A cosine function behavior is obtained by both methods for the first quantum state. The calculated bandgap value by EMA is almost twice smaller than that of the FAM. Also, a fluctuating current is predicted by both methods but in different oscillation values.

  18. Mesostructured metal germanium sulfides

    Energy Technology Data Exchange (ETDEWEB)

    MacLachlan, M.J.; Coombs, N.; Bedard, R.L.; White, S.; Thompson, L.K.; Ozin, G.A.

    1999-12-29

    A new class of mesostructured metal germanium sulfide materials has been prepared and characterized. The synthesis, via supramolecular assembly of well-defined germanium sulfide anionic cluster precursors and transition-metal cations in formamide, represents a new strategy for the formation of this class of solids. A variety of techniques were employed to examine the structure and composition of the materials. Structurally, the material is best described as a periodic mesostructured metal sulfide-based coordination framework akin to periodic hexagonal mesoporous silica, MCM-41. At the molecular scale, the materials strongly resemble microstructured metal germanium sulfides, in which the structure of the [Ge{sub 4}S{sub 10}]{sup 4{minus}} cluster building-blocks are intact and linked via {mu}-S-M-S bonds. Evidence for a metal-metal bond in mesostructured Cu/Ge{sub 4}S{sub 10} is also provided.

  19. New channeling effects in the radiative emission of 150 GeV electrons in a thin germanium crystal

    International Nuclear Information System (INIS)

    Belkacem, A.; Chevallier, M.; Gaillard, M.J.; Genre, R.; Kirsch, R.; Poizat, J.C.; Remillieux, J.; Bologna, G.; Peigneux, J.P.; Sillou, D.; Spighel, M.; Cue, N.; Kimball, J.C.; Marsh, B.; Sun, C.R.

    1986-01-01

    The orientation dependence of the radiative emission of 150 GeV electrons and positrons incident at small angles with respect to the axial direction of a thin (0.185 mm) Ge crystal has been observed. The processes are well understood, except for channeled electrons, which radiate unexpected high energy photons. (orig.)

  20. Calibration of germanium detectors

    International Nuclear Information System (INIS)

    Debertin, K.

    1983-01-01

    The process of determining the energy-dependent detection probability with measurements using Ge (Li) and high-grade germanium detectors is described. The paper explains which standards are best for a given purpose and given requirements as to accuracy, and how to assess measuring geometry variations and summation corrections. (DG) [de

  1. Photon multiplicity in the hard radiation of 150 GeV electrons in an aligned germanium crystal

    International Nuclear Information System (INIS)

    Belkacem, A.; Chevallier, M.; Gaillard, M.J.; Genre, R.; Kirsch, R.; Poizat, J.C.; Remillieux, J.; Bologna, G.; Peigneux, J.P.; Sillou, D.; Spighel, M.; Cue, N.; Kimball, J.C.; Marsh, B.B.; Sun, C.R.

    1988-01-01

    Mean values m of photon multiplicity in the radiation of 150 GeV electrons directed at and near the axis of a 0.185 mm thick Ge crystal cooled to 100 K have been deduced from the measurements of pair conversion probabilities. Depending on the distribution of multiplicity assumed, values of m ranging from 3.8 to 4.3 are obtained for the previously reported anomalous radiation peak. (orig.)

  2. Nuclear interactions for 15 GeV/c protons and pions under random and channeling conditions in germanium single crystals

    CERN Document Server

    Andersen, S K; Fich, O.; Golovchenko, J.A.; Nielsen, Henry; Schiott, H.E.; Uggerhoj, E.; Vraast-Thomsen, C.; Charpak, Georges; Petersen, G.; Sauli, F.; Ponpon, J.P.; Siffert, P.

    1978-01-01

    Strong directional effects for nuclear-reaction probabilities have been observed when 15 GeV/ c protons and pions are incident on a 4.2 mm Ge single crystal. In the random situation, our measurements are in agreement with Glauber's theory of diffraction scattering and with published particle-production data. When protons are incident in an aligned direction, the nuclear-reaction probabilities fall off very drastically but in a way which is in agreement with standard channeling theory; for aligned negative pions where a simple channeling theory is lacking, there is some experimental indication that nuclear-reaction probabilities are enhanced compared to the corresponding random rates, an indication which is supported by detailed computer-simulation studies.

  3. A potential method using Ge{iPrNC[N(SiMe_3)_2]NiPr}{sub 2}, (Et{sub 3}Si){sub 2}Te and anhydrous hydrazine for germanium tellurides

    Energy Technology Data Exchange (ETDEWEB)

    Du, Liyong; Du, Shulei; Ding, Yuqiang [School of Chemical and Material Engineering, Jiangnan University, Wuxi (China)

    2017-12-29

    A germanium(II)-guanidine derivative of formula Ge{iPrNC[N(SiMe_3)_2]NiPr}{sub 2} (1) was synthesized and characterized by {sup 1}H NMR, {sup 13}C NMR, elemental analysis, and X-ray diffraction method. Thermal property was also studied to identify its thermal stability and volatility. More importantly, compound 1 was synthesized to develop a new method for germanium tellurides, where anhydrous hydrazine was introduced to prompt the activity of germanium(II) guanidines (or derivatives) towards (Et{sub 3}Si){sub 2}Te. Solution reaction of compound 1, (Et{sub 3}Si){sub 2}Te, and anhydrous hydrazine was investigated to pre-identify the feasibility of this combination for ALD process. The EDS data of the black precipitate from this reaction verified the potential of this method to manufacture germanium tellurides. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Active volume studies with depleted and enriched BEGe detectors

    Energy Technology Data Exchange (ETDEWEB)

    Sturm, Katharina von [Eberhard Karls Universitaet Tuebingen (Germany); Universita degli Studi di Padova, Padua (Italy); Collaboration: GERDA-Collaboration

    2013-07-01

    The Gerda experiment is currently taking data for the search of the 0νββ decay in {sup 76}Ge. In 2013, 30 newly manufactured Broad Energy Germanium (BEGe) diodes will be deployed which will double the active mass within Gerda. These detectors were fabricated from high-purity germanium enriched in {sup 76}Ge and tested in the HADES underground laboratory, owned by SCK.CEN, in Mol, Belgium. As the BEGes are source and detector at the same time, one crucial parameter is their active volume which directly enters into the evaluation of the half-life. This talk illustrates the dead layer and active volume determination of prototype detectors from depleted germanium as well as the newly produced detectors from enriched material, using gamma spectroscopy methods and comparing experimental results to Monte-Carlo simulations. Recent measurements and their results are presented, and systematic effects are discussed.

  5. Characterization of nanocrystalline silicon germanium film and ...

    African Journals Online (AJOL)

    The nanocrystalline silicon-germanium films (Si/Ge) and Si/Ge nanotubes have low band gaps and high carrier mobility, thus offering appealing potential for absorbing gas molecules. Interaction between hydrogen molecules and bare as well as functionalized Si/Ge nanofilm and nanotube was investigated using Monte ...

  6. Pulse shapes and surface effects in segmented germanium detectors

    International Nuclear Information System (INIS)

    Lenz, Daniel

    2010-01-01

    It is well established that at least two neutrinos are massive. The absolute neutrino mass scale and the neutrino hierarchy are still unknown. In addition, it is not known whether the neutrino is a Dirac or a Majorana particle. The GERmanium Detector Array (GERDA) will be used to search for neutrinoless double beta decay of 76 Ge. The discovery of this decay could help to answer the open questions. In the GERDA experiment, germanium detectors enriched in the isotope 76 Ge are used as source and detector at the same time. The experiment is planned in two phases. In the first, phase existing detectors are deployed. In the second phase, additional detectors will be added. These detectors can be segmented. A low background index around the Q value of the decay is important to maximize the sensitivity of the experiment. This can be achieved through anti-coincidences between segments and through pulse shape analysis. The background index due to radioactive decays in the detector strings and the detectors themselves was estimated, using Monte Carlo simulations for a nominal GERDA Phase II array with 18-fold segmented germanium detectors. A pulse shape simulation package was developed for segmented high-purity germanium detectors. The pulse shape simulation was validated with data taken with an 19-fold segmented high-purity germanium detector. The main part of the detector is 18-fold segmented, 6-fold in the azimuthal angle and 3-fold in the height. A 19th segment of 5mm thickness was created on the top surface of the detector. The detector was characterized and events with energy deposited in the top segment were studied in detail. It was found that the metalization close to the end of the detector is very important with respect to the length of the of the pulses observed. In addition indications for n-type and p-type surface channels were found. (orig.)

  7. Pulse shapes and surface effects in segmented germanium detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lenz, Daniel

    2010-03-24

    It is well established that at least two neutrinos are massive. The absolute neutrino mass scale and the neutrino hierarchy are still unknown. In addition, it is not known whether the neutrino is a Dirac or a Majorana particle. The GERmanium Detector Array (GERDA) will be used to search for neutrinoless double beta decay of {sup 76}Ge. The discovery of this decay could help to answer the open questions. In the GERDA experiment, germanium detectors enriched in the isotope {sup 76}Ge are used as source and detector at the same time. The experiment is planned in two phases. In the first, phase existing detectors are deployed. In the second phase, additional detectors will be added. These detectors can be segmented. A low background index around the Q value of the decay is important to maximize the sensitivity of the experiment. This can be achieved through anti-coincidences between segments and through pulse shape analysis. The background index due to radioactive decays in the detector strings and the detectors themselves was estimated, using Monte Carlo simulations for a nominal GERDA Phase II array with 18-fold segmented germanium detectors. A pulse shape simulation package was developed for segmented high-purity germanium detectors. The pulse shape simulation was validated with data taken with an 19-fold segmented high-purity germanium detector. The main part of the detector is 18-fold segmented, 6-fold in the azimuthal angle and 3-fold in the height. A 19th segment of 5mm thickness was created on the top surface of the detector. The detector was characterized and events with energy deposited in the top segment were studied in detail. It was found that the metalization close to the end of the detector is very important with respect to the length of the of the pulses observed. In addition indications for n-type and p-type surface channels were found. (orig.)

  8. Germanium detector studies in the framework of the GERDA experiment

    Energy Technology Data Exchange (ETDEWEB)

    Budjas, Dusan

    2009-05-06

    The GERmanium Detector Array (GERDA) is an ultra-low background experiment under construction at Laboratori Nazionali del Gran Sasso. GERDA will search for {sup 76}Ge neutrinoless double beta decay with an aim for 100-fold reduction in background compared to predecessor experiments. This ambition necessitates innovative design approaches, strict selection of low-radioactivity materials, and novel techniques for active background suppression. The core feature of GERDA is its array of germanium detectors for ionizing radiation, which are enriched in {sup 76}Ge. Germanium detectors are the central theme of this dissertation. The first part describes the implementation, testing, and optimisation of Monte Carlo simulations of germanium spectrometers, intensively involved in the selection of low-radioactivity materials. The simulations are essential for evaluations of the gamma ray measurements. The second part concerns the development and validation of an active background suppression technique based on germanium detector signal shape analysis. This was performed for the first time using a BEGe-type detector, which features a small read-out electrode. As a result of this work, BEGe is now one of the two detector technologies included in research and development for the second phase of the GERDA experiment. A suppression of major GERDA backgrounds is demonstrated, with (0.93{+-}0.08)% survival probability for events from {sup 60}Co, (21{+-}3)% for {sup 226}Ra, and (40{+-}2)% for {sup 228}Th. The acceptance of {sup 228}Th double escape events, which are analogous to double beta decay, was kept at (89{+-}1)%. (orig.)

  9. Cosmogenically-produced isotopes in natural and enriched high-purity germanium detectors for the MAJORANA DEMONSTRATOR

    Science.gov (United States)

    Gilliss, Thomas; MAJORANA DEMONSTRATOR Collaboration

    2017-01-01

    The MAJORANA DEMONSTRATOR advances toward measurements of the neutrinoless double-beta decay of 76Ge. Detectors employed in the DEMONSTRATOR are subject to cosmogenic spallation during production and processing, resulting in activation of certain long-lived radioisotopes. Activation of these cosmogenic isotopes is mitigated by shielded storage of detectors and through underground operation of the DEMONSTRATOR at the 4850 ft level of the Sanford Underground Research Facility. In this work, we explore the appearance and reduction of cosmogenic contributions to the DEMONSTRATOR background spectrum. This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, the Particle Astrophysics and Nuclear Physics Programs of the National Science Foundation, and the Sanford Underground Research Facility.

  10. Solution synthesis of germanium nanocrystals

    Science.gov (United States)

    Gerung, Henry [Albuquerque, NM; Boyle, Timothy J [Kensington, MD; Bunge, Scott D [Cuyahoga Falls, OH

    2009-09-22

    A method for providing a route for the synthesis of a Ge(0) nanometer-sized material from. A Ge(II) precursor is dissolved in a ligand heated to a temperature, generally between approximately 100.degree. C. and 400.degree. C., sufficient to thermally reduce the Ge(II) to Ge(0), where the ligand is a compound that can bond to the surface of the germanium nanomaterials to subsequently prevent agglomeration of the nanomaterials. The ligand encapsulates the surface of the Ge(0) material to prevent agglomeration. The resulting solution is cooled for handling, with the cooling characteristics useful in controlling the size and size distribution of the Ge(0) materials. The characteristics of the Ge(II) precursor determine whether the Ge(0) materials that result will be nanocrystals or nanowires.

  11. Interactions of germanium atoms with silica surfaces

    International Nuclear Information System (INIS)

    Stanley, Scott K.; Coffee, Shawn S.; Ekerdt, John G.

    2005-01-01

    GeH 4 is thermally cracked over a hot filament depositing 0.7-15 ML Ge onto 2-7 nm SiO 2 /Si(1 0 0) at substrate temperatures of 300-970 K. Ge bonding changes are analyzed during annealing with X-ray photoelectron spectroscopy. Ge, GeH x , GeO, and GeO 2 desorption is monitored through temperature programmed desorption in the temperature range 300-1000 K. Low temperature desorption features are attributed to GeO and GeH 4 . No GeO 2 desorption is observed, but GeO 2 decomposition to Ge through high temperature pathways is seen above 750 K. Germanium oxidization results from Ge etching of the oxide substrate. With these results, explanations for the failure of conventional chemical vapor deposition to produce Ge nanocrystals on SiO 2 surfaces are proposed

  12. Analytical product study of germanium-containing medicine by different ICP-MS applications

    NARCIS (Netherlands)

    Krystek, Petra; Ritsema, Rob

    2004-01-01

    For several years organo-germanium containing medicine has been used for special treatments of e.g. cancer and AIDS. The active substances contain germanium as beta-carboxyethylgermanium sesquioxide ((GeCH2CH 2COO-H)2O3/"Ge-132"), spirogermanium, germanium-lactate-citrate or unspecified forms. For

  13. Study of three dimensional germanium islands and ultrathin Si{sub x}Ge{sub 1-x} films grown by chemical vapour deposition on Si(111)-(7 x 7)

    Energy Technology Data Exchange (ETDEWEB)

    Gopalakrishnan, Selvi

    2005-07-15

    This work probed at the atomic level, processes that occur during the Ge three dimensional island formation and on ultrathin Si{sub x}Ge{sub 1-x} epitaxial growth by chemical vapour deposition on the Si(111)-(7 x 7) substrate with the aid of surface probe techniques such as STM and AFM, XPS, as well as TEM imaging of any 3D island formation. This work could essentially be divided into two parts. The first part studied the growth of the strained Ge on Si system with emphasis on the characterisation of the CVD grown three dimensional germanium islands on a standard Si(111)-(7 x 7) substrate as well as on a surface modified Si(111)-(7 x 7) substrate. The characterisation was carried out using a combination of techniques. XPS was used to calculate the effective coverages of deposited germanium, the STM was used to image the top most layers whenever possible and AFM, cross-sectional TEM and HRTEM to image the three dimensional islands. The possible causes of the surface modification were also examined. In the second part of this work the growth morphologies ultrathin Si{sub x}Ge{sub 1-x} layers grown on the Si(111)-(7 x 7) substrate at 750 K where the hydrogen desorption rate from the Si(111) surface is low and at 850 K which was the temperature at which the rate of hydrogen desorption from the Si(111) surface was a maximum were investigated. In addition modelling of ultrathin layer growth was carried out using two existing growth models. (orig.)

  14. Germanium and indium

    Science.gov (United States)

    Shanks, W.C. Pat; Kimball, Bryn E.; Tolcin, Amy C.; Guberman, David E.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Germanium and indium are two important elements used in electronics devices, flat-panel display screens, light-emitting diodes, night vision devices, optical fiber, optical lens systems, and solar power arrays. Germanium and indium are treated together in this chapter because they have similar technological uses and because both are recovered as byproducts, mainly from copper and zinc sulfides.The world’s total production of germanium in 2011 was estimated to be 118 metric tons. This total comprised germanium recovered from zinc concentrates, from fly ash residues from coal burning, and from recycled material. Worldwide, primary germanium was recovered in Canada from zinc concentrates shipped from the United States; in China from zinc residues and coal from multiple sources in China and elsewhere; in Finland from zinc concentrates from the Democratic Republic of the Congo; and in Russia from coal.World production of indium metal was estimated to be about 723 metric tons in 2011; more than one-half of the total was produced in China. Other leading producers included Belgium, Canada, Japan, and the Republic of Korea. These five countries accounted for nearly 95 percent of primary indium production.Deposit types that contain significant amounts of germanium include volcanogenic massive sulfide (VMS) deposits, sedimentary exhalative (SEDEX) deposits, Mississippi Valley-type (MVT) lead-zinc deposits (including Irish-type zinc-lead deposits), Kipushi-type zinc-lead-copper replacement bodies in carbonate rocks, and coal deposits.More than one-half of the byproduct indium in the world is produced in southern China from VMS and SEDEX deposits, and much of the remainder is produced from zinc concentrates from MVT deposits. The Laochang deposit in Yunnan Province, China, and the VMS deposits of the Murchison greenstone belt in Limpopo Province, South Africa, provide excellent examples of indium-enriched deposits. The SEDEX deposits at Bainiuchang, China (located in

  15. Silicon germanium (SiGe) radioisotope thermoelectric generator (RTG) program for space missions. Nineteenth technical progress report, December 1980-January 1981

    International Nuclear Information System (INIS)

    1981-01-01

    Work accomplished during the reporting period on the DOE Silicon Germanium RTG Program, Contract DE-AC01-79ET-32043 is described. This program consists of the following three tasks: multi-hundred watt RTG for the Galileo probe mission; reestablishment of silicon germanium unicouple capability; and general purpose heat source RTG for the international solar polar and Galileo orbiter missions. Details of program progress for each task, including a milestone schedule and a discussion of current problem areas (if any) are presented

  16. Germanium soup

    Science.gov (United States)

    Palmer, Troy A.; Alexay, Christopher C.

    2006-05-01

    This paper addresses the variety and impact of dispersive model variations for infrared materials and, in particular, the level to which certain optical designs are affected by this potential variation in germanium. This work offers a method for anticipating and/or minimizing the pitfalls such potential model variations may have on a candidate optical design.

  17. Fabrication of core-shell nanostructures via silicon on insulator dewetting and germanium condensation: towards a strain tuning method for SiGe-based heterostructures in a three-dimensional geometry.

    Science.gov (United States)

    Naffouti, Meher; David, Thomas; Benkouider, Abdelmalek; Favre, Luc; Cabie, Martiane; Ronda, Antoine; Berbezier, Isabelle; Abbarchi, Marco

    2016-07-29

    We report on a novel method for the implementation of core-shell SiGe-based nanocrystals combining silicon on insulator dewetting in a molecular beam epitaxy reactor with an ex situ Ge condensation process. With an in situ two-step process (annealing and Ge deposition) we produce two families of islands on the same sample: Si-rich, formed during the first step and, all around them, Ge-rich formed after Ge deposition. By increasing the amount of Ge deposited on the annealed samples from 0 to 18 monolayers, the islands' shape in the Si-rich zones can be tuned from elongated and flat to more symmetric and with a larger vertical aspect ratio. At the same time, the spatial extension of the Ge-rich zones is progressively increased as well as the Ge content in the islands. Further processing by ex situ rapid thermal oxidation results in the formation of a core-shell composition profile in both Si and Ge-rich zones with atomically sharp heterointerfaces. The Ge condensation induces a Ge enrichment of the islands' shell of up to 50% while keeping a pure Si core in the Si-rich zones and a ∼25% SiGe alloy in the Ge-rich ones. The large lattice mismatch between core and shell, the absence of dislocations and the islands' monocrystalline nature render this novel class of nanostructures a promising device platform for strain-based band-gap engineering. Finally, this method can be used for the implementation of ultralarge scale meta-surfaces with dielectric Mie resonators for light manipulation at the nanoscale.

  18. Mesostructured germanium with cubic pore symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Armatas, G S; Kanatzidis, M G [Michigan State Univ., Michigan (United States), Dept. of Chemistry

    2006-11-15

    Regular mesoporous oxide materials have been widely studied and have a range of potential applications, such as catalysis, absorption and separation. They are not generally considered for their optical and electronic properties. Elemental semiconductors with nanopores running through them represent a different form of framework material with physical characteristics contrasting with those of the more conventional bulk, thin film and nanocrystalline forms. Here we describe cubic meso structured germanium, MSU-Ge-l, with gyroidal channels containing surfactant molecules, separated by amorphous walls that lie on the gyroid (G) minimal surface as in the mesoporous silica MCM-48. Although Ge is a high-meltin covalent semiconductor that is difficult to prepare from solution polymerization, we succeeded in assembling a continuous Ge network using a suitable precursor for Ge{sup 4-} atoms. Our results indicate that elemental semiconductors from group 14 of the periodic table can be made to adopt meso structured forms such as MSU-Ge-1, which features two three-dimensional labyrinthine tunnels obeying la3d space group symmetry and separated by a continuous germanium minimal surface that is otherwise amorphous. A consequence of this new structure for germanium, which has walls only one nanometre thick, is a wider electronic energy bandgap (1.4 eV versus 0.66 eV) than has crystalline or amorphous Ge. Controlled oxidation of MSU-Ge-1 creates a range of germanium suboxides with continuously varying Ge:O ratio and a smoothly increasing energy gap. (author)

  19. Smooth germanium nanowires prepared by a hydrothermal deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Pei, L.Z., E-mail: lzpei1977@163.com [School of Materials Science and Engineering, Institute of Molecular Engineering and Applied Chemistry, Key Laboratory of Materials Science and Processing of Anhui Province, Anhui University of Technology, Ma' anshan, Anhui 243002 (China); Zhao, H.S. [School of Materials Science and Engineering, Institute of Molecular Engineering and Applied Chemistry, Key Laboratory of Materials Science and Processing of Anhui Province, Anhui University of Technology, Ma' anshan, Anhui 243002 (China); Tan, W. [Henkel Huawei Electronics Co. Ltd., Lian' yungang, Jiangsu 222006 (China); Yu, H.Y. [School of Materials Science and Engineering, Institute of Molecular Engineering and Applied Chemistry, Key Laboratory of Materials Science and Processing of Anhui Province, Anhui University of Technology, Ma' anshan, Anhui 243002 (China); Chen, Y.W. [Department of Materials Science, Fudan University, Shanghai 200433 (China); Fan, C.G. [School of Materials Science and Engineering, Institute of Molecular Engineering and Applied Chemistry, Key Laboratory of Materials Science and Processing of Anhui Province, Anhui University of Technology, Ma' anshan, Anhui 243002 (China); Zhang, Qian-Feng, E-mail: zhangqf@ahut.edu.cn [School of Materials Science and Engineering, Institute of Molecular Engineering and Applied Chemistry, Key Laboratory of Materials Science and Processing of Anhui Province, Anhui University of Technology, Ma' anshan, Anhui 243002 (China)

    2009-11-15

    Smooth germanium nanowires were prepared using Ge and GeO{sub 2} as the starting materials and Cu sheet as the substrate by a simple hydrothermal deposition process. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations show that the germanium nanowires are smooth and straight with uniform diameter of about 150 nm in average and tens of micrometers in length. X-ray diffraction (XRD) and Raman spectrum of the germanium nanowires display that the germanium nanowires are mainly composed of cubic diamond phase. PL spectrum shows a strong blue light emission at 441 nm. The growth mechanism is also discussed.

  20. Smooth germanium nanowires prepared by a hydrothermal deposition process

    International Nuclear Information System (INIS)

    Pei, L.Z.; Zhao, H.S.; Tan, W.; Yu, H.Y.; Chen, Y.W.; Fan, C.G.; Zhang, Qian-Feng

    2009-01-01

    Smooth germanium nanowires were prepared using Ge and GeO 2 as the starting materials and Cu sheet as the substrate by a simple hydrothermal deposition process. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations show that the germanium nanowires are smooth and straight with uniform diameter of about 150 nm in average and tens of micrometers in length. X-ray diffraction (XRD) and Raman spectrum of the germanium nanowires display that the germanium nanowires are mainly composed of cubic diamond phase. PL spectrum shows a strong blue light emission at 441 nm. The growth mechanism is also discussed.

  1. Germanium Does Not Substitute for Boron in Cross-Linking of Rhamnogalacturonan II in Pumpkin Cell Walls1

    Science.gov (United States)

    Ishii, Tadashi; Matsunaga, Toshiro; Iwai, Hiroaki; Satoh, Shinobu; Taoshita, Junji

    2002-01-01

    Boron (B)-deficient pumpkin (Cucurbita moschata Duchesne) plants exhibit reduced growth, and their tissues are brittle. The leaf cell walls of these plants contain less than one-half the amount of borate cross-linked rhamnogalacturonan II (RG-II) dimer than normal plants. Supplying germanium (Ge), which has been reported to substitute for B, to B-deficient plants does not restore growth or reduce tissue brittleness. Nevertheless, the leaf cell walls of the Ge-treated plants accumulated considerable amounts of Ge. Dimeric RG-II (dRG-II) accounted for between 20% and 35% of the total RG-II in the cell walls of the second to fourth leaves from Ge-treated plants, but only 2% to 7% of the RG-II was cross-linked by germanate (dRG-II-Ge). The ability of RG-II to form a dimer is not reduced by Ge treatment because approximately 95% of the monomeric RG-II generated from the walls of Ge-treated plants is converted to dRG-II-Ge in vitro in the presence of germanium oxide and lead acetate. However, dRG-II-Ge is unstable and is converted to monomeric RG-II when the Ge is removed. Therefore, the content of dRG-II-Ge and dRG-II-B described above may not reflect the actual ratio of these in muro. 10B-Enriched boric acid and Ge are incorporated into the cell wall within 10 min after their foliar application to B-deficient plants. Foliar application of 10B but not Ge results in an increase in the proportion of dRG-II in the leaf cell wall. Taken together, our results suggest that Ge does not restore the growth of B-deficient plants. PMID:12481079

  2. Technology CAD for germanium CMOS circuit

    Energy Technology Data Exchange (ETDEWEB)

    Saha, A.R. [Department of Electronics and ECE, IIT Kharagpur, Kharagpur-721302 (India)]. E-mail: ars.iitkgp@gmail.com; Maiti, C.K. [Department of Electronics and ECE, IIT Kharagpur, Kharagpur-721302 (India)

    2006-12-15

    Process simulation for germanium MOSFETs (Ge-MOSFETs) has been performed in 2D SILVACO virtual wafer fabrication (VWF) suite towards the technology CAD for Ge-CMOS process development. Material parameters and mobility models for Germanium were incorporated in simulation via C-interpreter function. We also report on the device design issues along with the DC and RF characterization of the bulk Ge-MOSFETs, AC parameter extraction and circuit simulation of Ge-CMOS. Simulation results are compared with bulk-Si devices. Simulations predict a cut-off frequency, f {sub T} of about 175 GHz for Ge-MOSFETs compared to 70 GHz for a similar gate-length Si MOSFET. For a single stage Ge-CMOS inverter circuit, a GATE delay of 0.6 ns is predicted.

  3. Technology CAD for germanium CMOS circuit

    International Nuclear Information System (INIS)

    Saha, A.R.; Maiti, C.K.

    2006-01-01

    Process simulation for germanium MOSFETs (Ge-MOSFETs) has been performed in 2D SILVACO virtual wafer fabrication (VWF) suite towards the technology CAD for Ge-CMOS process development. Material parameters and mobility models for Germanium were incorporated in simulation via C-interpreter function. We also report on the device design issues along with the DC and RF characterization of the bulk Ge-MOSFETs, AC parameter extraction and circuit simulation of Ge-CMOS. Simulation results are compared with bulk-Si devices. Simulations predict a cut-off frequency, f T of about 175 GHz for Ge-MOSFETs compared to 70 GHz for a similar gate-length Si MOSFET. For a single stage Ge-CMOS inverter circuit, a GATE delay of 0.6 ns is predicted

  4. Blocking germanium diffusion inside silicon dioxide using a co-implanted silicon barrier

    Science.gov (United States)

    Barba, D.; Wang, C.; Nélis, A.; Terwagne, G.; Rosei, F.

    2018-04-01

    We investigate the effect of co-implanting a silicon sublayer on the thermal diffusion of germanium ions implanted into SiO2 and the growth of Ge nanocrystals (Ge-ncs). High-resolution imaging obtained by transmission electron microscopy and energy dispersive spectroscopy measurements supported by Monte-Carlo calculations shows that the Si-enriched region acts as a diffusion barrier for Ge atoms. This barrier prevents Ge outgassing during thermal annealing at 1100 °C. Both the localization and the reduced size of Ge-ncs formed within the sample region co-implanted with Si are observed, as well as the nucleation of mixed Ge/Si nanocrystals containing structural point defects and stacking faults. Although it was found that the Si co-implantation affects the crystallinity of the formed Ge-ncs, this technique can be implemented to produce size-selective and depth-ordered nanostructured systems by controlling the spatial distribution of diffusing Ge. We illustrate this feature for Ge-ncs embedded within a single SiO2 monolayer, whose diameters were gradually increased from 1 nm to 5 nm over a depth of 100 nm.

  5. Amorphous germanium as an electron or hole blocking contact on high-purity germanium detectors

    International Nuclear Information System (INIS)

    Hansen, W.L.; Haller, E.E.

    1976-10-01

    Experiments were performed in an attempt to make thin n + contacts on high-purity germanium by the solid phase/sup 1)/ epitaxial regrowth of arsenic doped amorphous germanium. After cleaning the crystal surface with argon sputtering and trying many combinations of layers, it was not found possible to induce recrystallization below 400 0 C. However, it was found that simple thermally evaporated amorphous Ge made fairly good electron or hole blocking contacts. Excellent spectrometers have been made with amorphous Ge replacing the n + contact. As presently produced, the amorphous Ge contact diodes show a large variation in high-voltage leakage current

  6. The isotope composition of inorganic germanium in seawater and deep sea sponges

    Science.gov (United States)

    Guillermic, Maxence; Lalonde, Stefan V.; Hendry, Katharine R.; Rouxel, Olivier J.

    2017-09-01

    Although dissolved concentrations of germanium (Ge) and silicon (Si) in modern seawater are tightly correlated, uncertainties still exist in the modern marine Ge cycle. Germanium stable isotope systematics in marine systems should provide additional constraints on marine Ge sources and sinks, however the low concentration of Ge in seawater presents an analytical challenge for isotopic measurement. Here, we present a new method of pre-concentration of inorganic Ge from seawater which was applied to measure three Ge isotope profiles in the Southern Ocean and deep seawater from the Atlantic and Pacific Oceans. Germanium isotopic measurements were performed on Ge amounts as low as 2.6 ng using a double-spike approach and a hydride generation system coupled to a MC-ICP-MS. Germanium was co-precipitated with iron hydroxide and then purified through anion-exchange chromatography. Results for the deep (i.e. >1000 m depth) Pacific Ocean off Hawaii (nearby Loihi Seamount) and the deep Atlantic off Bermuda (BATS station) showed nearly identical δ74/70Ge values at 3.19 ± 0.31‰ (2SD, n = 9) and 2.93 ± 0.10‰ (2SD, n = 2), respectively. Vertical distributions of Ge concentration and isotope composition in the deep Southern Ocean for water depth > 1300 m yielded an average δ74/70Ge = 3.13 ± 0.25‰ (2SD, n = 14) and Ge/Si = 0.80 ± 0.09 μmol/mol (2SD, n = 12). Significant variations in δ74/70Ge, from 2.62 to 3.71‰, were measured in the first 1000 m in one station of the Southern Ocean near Sars Seamount in the Drake Passage, with the heaviest values measured in surface waters. Isotope fractionation by diatoms during opal biomineralization may explain the enrichment in heavy isotopes for both Ge and Si in surface seawater. However, examination of both oceanographic parameters and δ74/70Ge values suggest also that water mass mixing and potential contribution of shelf-derived Ge also could contribute to the variations. Combining these results with new Ge isotope data

  7. Manufacturing P-N junctions in germanium bodies

    International Nuclear Information System (INIS)

    Hall, R.N.

    1980-01-01

    A method of producing p-n junctions in Ge so as to facilitate their use as radiation detectors involves forming a body of high purity p-type germanium, diffusing lithium deep into the body, in the absence of electrolytic processes, to form a junction between n-type and p-type germanium greater than 1 mm depth. (UK)

  8. Research and Development Supporting a Next Generation Germanium Double Beta Decay Experiment

    Science.gov (United States)

    Rielage, Keith; Elliott, Steve; Chu, Pinghan; Goett, Johnny; Massarczyk, Ralph; Xu, Wenqin

    2015-10-01

    To improve the search for neutrinoless double beta decay, the next-generation experiments will increase in source mass and continue to reduce backgrounds in the region of interest. A promising technology for the next generation experiment is large arrays of Germanium p-type point contact detectors enriched in 76-Ge. The experience, expertise and lessons learned from the MAJORANA DEMONSTRATOR and GERDA experiments naturally lead to a number of research and development activities that will be useful in guiding a future experiment utilizing Germanium. We will discuss some R&D activities including a hybrid cryostat design, background reduction in cabling, connectors and electronics, and modifications to reduce assembly time. We acknowledge the support of the U.S. Department of Energy through the LANL/LDRD Program.

  9. Near-infrared emission from mesoporous crystalline germanium

    Energy Technology Data Exchange (ETDEWEB)

    Boucherif, Abderraouf; Aimez, Vincent; Arès, Richard, E-mail: richard.ares@usherbrooke.ca [Institut Interdisciplinaire d’Innovation Technologique (3IT), Université de Sherbrooke, 3000 Boulevard Université, Sherbrooke, J1K OA5, Québec (Canada); Laboratoire Nanotechnologies Nanosystèmes (LN2)-CNRS UMI-3463, Université de Sherbrooke, 3000 Boulevard Université, Sherbrooke, J1K OA5, Québec (Canada); Korinek, Andreas [Canadian Centre for Electron Microscopy, Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario, L8S 4M1 (Canada)

    2014-10-15

    Mesoporous crystalline germanium was fabricated by bipolar electrochemical etching of Ge wafer in HF-based electrolyte. It yields uniform mesoporous germanium layers composed of high density of crystallites with an average size 5-7 nm. Subsequent extended chemical etching allows tuning of crystallites size while preserving the same chemical composition. This highly controllable nanostructure exhibits photoluminescence emission above the bulk Ge bandgap, in the near-infrared range (1095-1360nm) with strong evidence of quantum confinement within the crystallites.

  10. GERDA - a new neutrinoless double beta experiment using 76Ge

    International Nuclear Information System (INIS)

    Meierhofer, G

    2011-01-01

    The search for neutrinoless double beta decay (0νssss) has been a very active field for the last decades. While double beta decay has been observed, 0νssss decay still waits for its experimental proof. The GErmanium Detector Array (GERDA) uses 76 Ge, an ideal candidate as it is acting as source and detector simultaneously. Germanium detectors, isotopically enriched in 76 Ge are submerged directly into an ultra pure cryo liquid, which serves as coolant and radiation shield. This concept will allow to reduce the background by up to two orders of magnitude with respect to earlier experiments. GERDA has been constructed in hall A of the underground laboratory LNGS of the INFN in Italy. The experiment started recently with a test run.

  11. Germanium films by polymer-assisted deposition

    Science.gov (United States)

    Jia, Quanxi; Burrell, Anthony K.; Bauer, Eve; Ronning, Filip; McCleskey, Thomas Mark; Zou, Guifu

    2013-01-15

    Highly ordered Ge films are prepared directly on single crystal Si substrates by applying an aqueous coating solution having Ge-bound polymer onto the substrate and then heating in a hydrogen-containing atmosphere. A coating solution was prepared by mixing water, a germanium compound, ethylenediaminetetraacetic acid, and polyethyleneimine to form a first aqueous solution and then subjecting the first aqueous solution to ultrafiltration.

  12. Structure of compensating centers in neutron irradiated n-type germanium

    International Nuclear Information System (INIS)

    Erchak, D.P.; Kosobutskij, V.S.; Stel'makh, V.F.

    1989-01-01

    Structural model of one of the main compensating defects of Ge-M1, Ge-M5, Ge-M6 in neutron irradiated (10 18 -10 20 cm -2 ) germanium, strongly alloyed (2x10 18 -3x10 19 cm -3 ) with antimony, phosphorus and arsenic respectively, is suggested. The above mentioned compensating centers are paramagnetic in a positive charge state and represent a vacancy, two nearby germanium atoms of which are replaced with two atoms of corresponding fine donor impurity. It is mainly contributed (63%- for Ge-M5 centers, 56% - for Ge-M6 centers) by orbitals of two germanium atoms neighbouring the vacancy. The angle of the bonds of each of two mentioned germanium atoms with its three neighbours and orientation of maximum electron density of hybride orbital, binding both germanium atoms, is approximately by 5 deg greater the tetrahedral one

  13. Melting point of high-purity germanium stable isotopes

    Science.gov (United States)

    Gavva, V. A.; Bulanov, A. D.; Kut'in, A. M.; Plekhovich, A. D.; Churbanov, M. F.

    2018-05-01

    The melting point (Tm) of germanium stable isotopes 72Ge, 73Ge, 74Ge, 76Ge was determined by differential scanning calorimetry. With the increase in atomic mass of isotope the decrease in Tm is observed. The decrease was equal to 0.15 °C per the unit of atomic mass which qualitatively agrees with the value calculated by Lindemann formula accounting for the effect of "isotopic compression" of elementary cell.

  14. Germanium content in Polish hard coals

    Directory of Open Access Journals (Sweden)

    Makowska Dorota

    2016-01-01

    Full Text Available Due to the policy of the European Union, it is necessary to search for new sources of scarce raw materials. One of these materials is germanium, listed as a critical element. This semi-metal is widely used in the electronics industry, for example in the production of semiconductors, fibre optics and solar cells. Coal and fly ash from its combustion and gasification for a long time have been considered as a potential source of many critical elements, particularly germanium. The paper presents the results of germanium content determination in the Polish hard coal. 23 coal samples of various coal ranks were analysed. The samples were collected from 15 mines of the Upper Silesian Coal Basin and from one mine of the Lublin Coal Basin. The determination of germanium content was performed with the use of Atomic Absorption Spectrometry with Electrothermal Atomization (GFAAS. The investigation showed that germanium content in the analysed samples was at least twice lower than the average content of this element in the hard coals analysed so far and was in the range of 0.08 ÷ 1.28 mg/kg. Moreover, the content of Ge in the ashes from the studied coals does not exceed 15 mg/kg, which is lower than the average value of Ge content in the coal ashes. The highest content of this element characterizes coals of the Lublin Coal Basin and young coals type 31 from the Vistula region. The results indicate a low utility of the analysed coal ashes as a source of the recovery of germanium. On the basis of the analyses, the lack of the relationship between the content of the element and the ash content in the tested coals was noted. For coals of the Upper Silesian Coal Basin, the relationship between the content of germanium in the ashes and the depth of the seam was observed.

  15. Doping of germanium telluride with bismuth tellurides

    International Nuclear Information System (INIS)

    Abrikosov, N.Kh.; Karpinskij, O.G.; Makalatiya, T.Sh.; Shelimova, L.E.

    1981-01-01

    Effect of germanium telluride doping with bismuth fellurides (Bi 2 Te 3 ; BiTe; Bi 2 Te) on phase transition temperature, lattice parameters and electrophysical properties of alloys is studied. It is shown that in alloys of GeTe-Bi 2 Te 3 (BiTe)(Bi 2 Te) cross sections solid solution of GeTe with Bi 2 Te 3 , characterized by deviation from stoichiometry, and germanium in the second phase the quantity of which increases during the transition from GeTe-Bi 2 Te 3 cross section to GeTe-Bi 2 Te are in equilibrium. Lower values of holes concentration and of electric conductivity and higher values of thermo e.m.f. coefficient in comparison with alloys of GeTe-Bi 2 Te 3 cross section with the same bismuth content are characterized for GeTe-Bi 2 Te cross section alloys. It is shown that in the range of GeTe-base solid solution the α→γ phase transformation which runs trough the two-phase region (α→γ) is observed with tellurium content increase. Extension of α-phase existence region widens with the bismuth content increase. Peculiarities of interatomic interaction in GeTe-base solid solutions with isovalent and heterovalent cation substitution are considered [ru

  16. Neutron Transmission of Germanium Poly- and Monocrystals

    International Nuclear Information System (INIS)

    Habib, N.

    2009-01-01

    The measured total neutron cross-sections of germanium poly- and mono-crystals were analyzed using an additive formula. The formula takes into account the germanium crystalline structure and its physical parameters. Computer programs have developed in order to provide the required analyses. The calculated values of the total cross-section of polycrystalline germanium in the neutron wavelength range from 0.001 up to 0.7 nm were fitted to the measured ones at ETRR-1. From the fitting the main constants of the additive formula were determined. The experimental data measured at ETRR-1 of the total cross-section of high quality Ge single crystal at 4400 K, room, and liquid nitrogen temperatures, in the wavelength range between 0.028 nm and 0.64 nm, were also compared with the calculated values using the formula having the same constants. An overall agreement is noticed between the formula fits and experimental data. A feasibility study is done for the use of germanium in poly-crystalline form, as cold neutron filter, and in mono-crystalline one as an efficient filter for thermal neutrons. The filtering efficiency of Ge single crystal is detailed in terms of its isotopic abundance, crystal thickness, mosaic spread, and temperature. It can be concluded that the 7.5 cm thick 76 Ge single crystal (0.10 FWHM mosaic spread) cooled at liquid nitrogen temperature is an efficient thermal neutron filter.

  17. Status report on the International Germanium Experiment

    International Nuclear Information System (INIS)

    Brodzinski, R.L.; Hensley, W.K.; Miley, H.S.; Reeves, J.H.; Avignone, F.T.; Collar, J.I.; Guerard, C.K.; Courant, H.; Ruddick, K.; Kirpichnikov, I.V.; Starostin, A.S.; Osetrov, S.B.; Pomansky, A.A.; Smolnikov, A.A.; Vasiliev, S.I.

    1992-06-01

    Phase II detector fabrication for the International Germanium Experiment is awaiting resolution of technical details observed during Phase I. Measurements of fiducial volume, configuration of the tansistor-reset preamplifier stage, and sources of background are discussed. Cosmogenic 7 Be is measured in germanium. Radium contamination in electroformed copper reported. The 2ν double- beta decay half-life of 76 Ge measured with a Phase I detector is in reasonable agreement with previously reported values. No events are observed in the vicinity of the Oν double-beta decay energy

  18. Silicon germanium mask for deep silicon etching

    KAUST Repository

    Serry, Mohamed

    2014-07-29

    Polycrystalline silicon germanium (SiGe) can offer excellent etch selectivity to silicon during cryogenic deep reactive ion etching in an SF.sub.6/O.sub.2 plasma. Etch selectivity of over 800:1 (Si:SiGe) may be achieved at etch temperatures from -80 degrees Celsius to -140 degrees Celsius. High aspect ratio structures with high resolution may be patterned into Si substrates using SiGe as a hard mask layer for construction of microelectromechanical systems (MEMS) devices and semiconductor devices.

  19. Silicon germanium mask for deep silicon etching

    KAUST Repository

    Serry, Mohamed; Rubin, Andrew; Refaat, Mohamed; Sedky, Sherif; Abdo, Mohammad

    2014-01-01

    Polycrystalline silicon germanium (SiGe) can offer excellent etch selectivity to silicon during cryogenic deep reactive ion etching in an SF.sub.6/O.sub.2 plasma. Etch selectivity of over 800:1 (Si:SiGe) may be achieved at etch temperatures from -80 degrees Celsius to -140 degrees Celsius. High aspect ratio structures with high resolution may be patterned into Si substrates using SiGe as a hard mask layer for construction of microelectromechanical systems (MEMS) devices and semiconductor devices.

  20. In vitro binding of germanium to proteins of rice shoots

    International Nuclear Information System (INIS)

    Matsumoto, Hideaki; Takahashi, Eiichi

    1976-01-01

    The possibility of in vitro binding between proteins of rice shoots and germanium (Ge) was investigated. The proteins in mixtures of aqueous extracts of rice shoots and radioactive germanium ( 68 GeO 2 ) were fractionated. The binding of radioactivity to the proteins was observed even after 5 successive fractionation steps from the original mixtures. At the final fractionation step using polyacrylamide gel electrophoresis, a constant proportionality between protein concentration and associated radioactivity was found in most samples although not all. These results indicate that the binding of 68 Ge to proteins is not due to the simple adsorption by proteins. (auth.)

  1. First results of neutrinoless double beta decay search with the GERmanium Detector Array "GERDA"

    Science.gov (United States)

    Janicskó Csáthy, József

    2014-06-01

    The study of neutrinoless double beta decay is the most powerful approach to the fundamental question if the neutrino is a Majorana particle, i.e. its own anti-particle. The observation of the lepton number violating neutrinoless double beta decay would establish the Majorana nature of the neutrino. Until now neutrinoless double beta decay was not observed. The GERmanium Detector Array, GERDA is a double beta decay experiment located at the INFN Gran Sasso National Laboratory, Italy. GERDA operates bare Ge diodes enriched in 76Ge in liquid argon supplemented by a water shield. The exposure accumulated adds up to 21.6 kg· yr with a background level of 1.8 · 10-2 cts/(keV·kg·yr). The results of the Phase I of the experiment are presented and the preparation of the Phase II is briefly discussed.

  2. Porous germanium multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Garralaga Rojas, Enrique; Hensen, Jan; Brendel, Rolf [Institut fuer Solarenergieforschung Hameln (ISFH), Emmerthal (Germany); Carstensen, Juergen; Foell, Helmut [Chair for General Materials Science, Faculty of Engineering, Christian-Albrechts-University of Kiel (Germany)

    2011-06-15

    We present the reproducible fabrication of porous germanium (PGe) single- and multilayers. Mesoporous layers form on heavily doped 4'' p-type Ge wafers by electrochemical etching in highly concentrated HF-based electrolytes with concentrations in a range of 30-50 wt.%. Direct PGe formation is accompanied by a constant dissolution of the already-formed porous layer at the electrolyte/PGe interface, hence yielding a thinner substrate after etching. This effect inhibits multilayer formation as the starting layer is etched while forming the second layer. We avoid dissolution of the porous layer by alternating the etching bias from anodic to cathodic. PGe formation occurs during anodic etching whereas the cathodic step passivates pore walls with H-atoms and avoids electropolishing. The passivation lasts a limited time depending on the etching current density and electrolyte concentration, necessitating a repetition of the cathodic step at suitable intervals. With optimized alternating bias mesoporous multilayer production is possible. We control the porosity of each single layer by varying the etching current density and the electrolyte (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Next Generation Germanium Systems for Safeguards Applications

    International Nuclear Information System (INIS)

    Dreyer, J.; Burks, M.; Hull, E.

    2015-01-01

    We are developing the latest generation of highly portable, mechanically cooled germanium systems for safeguard applications. In collaboration with our industrial partner, Ph.D.s Co, we have developed the Germanium Gamma Ray Imager (GeGI), an imager with a 2π field of view. This instrument has been thoroughly field tested in a wide range of environments and have performed reliably even in the harshest conditions. The imaging capability of GeGI complements existing safeguards techniques by allowing for the spatial detection, identification, and characterization of nuclear material. Additionally, imaging can be used in design information verification activities to address potential material diversions. Measurements conducted at the Paducah Gaseous Diffusion Plant highlight the advantages this instrument offers in the identification and localization of LEU, HEU and Pu holdup. GeGI has also been deployed to the Savannah River Site for the measurement of radioactive waste canisters, providing information valuable for waste characterization and inventory accountancy. Measuring 30 x 15 x 23 cm and weighing approximately 15 kg, this instrument is the first portable germanium-based imager. GeGI offers high reliability with the convenience of mechanical cooling, making this instrument ideal for the next generation of safeguards instrumentation. (author)

  4. Electrodeposition of germanium from supercritical fluids.

    Science.gov (United States)

    Ke, Jie; Bartlett, Philip N; Cook, David; Easun, Timothy L; George, Michael W; Levason, William; Reid, Gillian; Smith, David; Su, Wenta; Zhang, Wenjian

    2012-01-28

    Several Ge(II) and Ge(IV) compounds were investigated as possible reagents for the electrodeposition of Ge from liquid CH(3)CN and CH(2)F(2) and supercritical CO(2) containing as a co-solvent CH(3)CN (scCO(2)) and supercritical CH(2)F(2) (scCH(2)F(2)). For Ge(II) reagents the most promising results were obtained using [NBu(n)(4)][GeCl(3)]. However the reproducibility was poor and the reduction currents were significantly less than the estimated mass transport limited values. Deposition of Ge containing films was possible at high cathodic potential from [NBu(n)(4)][GeCl(3)] in liquid CH(3)CN and supercritical CO(2) containing CH(3)CN but in all cases they were heavily contaminated by C, O, F and Cl. Much more promising results were obtained using GeCl(4) in liquid CH(2)F(2) and supercritical CH(2)F(2). In this case the reduction currents were consistent with mass transport limited reduction and bulk electrodeposition produced amorphous films of Ge. Characterisation by XPS showed the presence of low levels of O, F and C, XPS confirmed the presence of Ge together with germanium oxides, and Raman spectroscopy showed that the as deposited amorphous Ge could be crystallised by the laser used in obtaining the Raman measurements.

  5. Crystallization of Electrodeposited Germanium Thin Film on Silicon (100).

    Science.gov (United States)

    Abidin, Mastura Shafinaz Zainal; Matsumura, Ryo; Anisuzzaman, Mohammad; Park, Jong-Hyeok; Muta, Shunpei; Mahmood, Mohamad Rusop; Sadoh, Taizoh; Hashim, Abdul Manaf

    2013-11-06

    We report the crystallization of electrodeposited germanium (Ge) thin films on n-silicon (Si) (100) by rapid melting process. The electrodeposition was carried out in germanium (IV) chloride: propylene glycol (GeCl₄:C₃H₈O₂) electrolyte with constant current of 50 mA for 30 min. The measured Raman spectra and electron backscattering diffraction (EBSD) images show that the as-deposited Ge thin film was amorphous. The crystallization of deposited Ge was achieved by rapid thermal annealing (RTA) at 980 °C for 1 s. The EBSD images confirm that the orientations of the annealed Ge are similar to that of the Si substrate. The highly intense peak of Raman spectra at 300 cm -1 corresponding to Ge-Ge vibration mode was observed, indicating good crystal quality of Ge. An additional sub peak near to 390 cm -1 corresponding to the Si-Ge vibration mode was also observed, indicating the Ge-Si mixing at Ge/Si interface. Auger electron spectroscopy (AES) reveals that the intermixing depth was around 60 nm. The calculated Si fraction from Raman spectra was found to be in good agreement with the value estimated from Ge-Si equilibrium phase diagram. The proposed technique is expected to be an effective way to crystallize Ge films for various device applications as well as to create strain at the Ge-Si interface for enhancement of mobility.

  6. Crystallization of Electrodeposited Germanium Thin Film on Silicon (100

    Directory of Open Access Journals (Sweden)

    Abdul Manaf Hashim

    2013-11-01

    Full Text Available We report the crystallization of electrodeposited germanium (Ge thin films on n-silicon (Si (100 by rapid melting process. The electrodeposition was carried out in germanium (IV chloride: propylene glycol (GeCl4:C3H8O2 electrolyte with constant current of 50 mA for 30 min. The measured Raman spectra and electron backscattering diffraction (EBSD images show that the as-deposited Ge thin film was amorphous. The crystallization of deposited Ge was achieved by rapid thermal annealing (RTA at 980 °C for 1 s. The EBSD images confirm that the orientations of the annealed Ge are similar to that of the Si substrate. The highly intense peak of Raman spectra at 300 cm−1 corresponding to Ge-Ge vibration mode was observed, indicating good crystal quality of Ge. An additional sub peak near to 390 cm−1 corresponding to the Si-Ge vibration mode was also observed, indicating the Ge-Si mixing at Ge/Si interface. Auger electron spectroscopy (AES reveals that the intermixing depth was around 60 nm. The calculated Si fraction from Raman spectra was found to be in good agreement with the value estimated from Ge-Si equilibrium phase diagram. The proposed technique is expected to be an effective way to crystallize Ge films for various device applications as well as to create strain at the Ge-Si interface for enhancement of mobility.

  7. Limit on Neutrinoless Double Beta Decay of 76Ge by GERDA

    Science.gov (United States)

    Agostini, M.; Allardt, M.; Andreotti, E.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Heider, M. Barabè; Barros, N.; Baudis, L.; Bauer, C.; Becerici-Schmidt, N.; Bellotti, E.; Belogurov, S.; Belyaev, S. T.; Benato, G.; Bettini, A.; Bezrukov, L.; Bode, T.; Brudanin, V.; Brugnera, R.; Budjáš, D.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; Cossavella, F.; Demidova, E. V.; Domula, A.; Egorov, V.; Falkenstein, R.; Ferella, A.; Freund, K.; Frodyma, N.; Gangapshev, A.; Garfagnini, A.; Gotti, C.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Guthikonda, K. K.; Hampel, W.; Hegai, A.; Heisel, M.; Hemmer, S.; Heusser, G.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Csáthy, J. Janicskó; Jochum, J.; Junker, M.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Klimenko, A.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lebedev, V. I.; Lehnert, B.; Liao, H. Y.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Machado, A. A.; Macolino, C.; Majorovits, B.; Maneschg, W.; Misiaszek, M.; Nemchenok, I.; Nisi, S.; Shaughnessy, C. O.'.; Pandola, L.; Pelczar, K.; Pessina, G.; Pullia, A.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salathe, M.; Schmitt, C.; Schreiner, J.; Schulz, O.; Schwingenheuer, B.; Schönert, S.; Shevchik, E.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Strecker, H.; Tarka, M.; Ur, C. A.; Vasenko, A. A.; Volynets, O.; von Sturm, K.; Wagner, V.; Walter, M.; Wegmann, A.; Wester, T.; Wojcik, M.; Yanovich, E.; Zavarise, P.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zuber, K.; Zuzel, G.

    The Gerda experiment at the Laboratori Nazionali del Gran Sasso in Italy uses germanium detectors made from material with an enriched 76Ge isotope fraction to search for neutrinoless double beta decay of this nucleus. Applying a blind analysis we find no signal after an exposure of 21.6 kg·yr and a background of about 0.01 cts/(keV·kg·yr). A half-life limit of Tov1/2> 2.1 · 1025 yr (90% C.L.) is extracted. The previous claim of a signal for 76Ge is excluded with 99% probability in a model independent way.

  8. Silver-compensated germanium center in α-quartz

    International Nuclear Information System (INIS)

    Laman, F.C.; Weil, J.A.

    1977-01-01

    A synthetic germanium-doped crystal of α-quartz was subjected to an electro-diffusion process (ca. 600 V/cm, 625 0 K), in which Ag + ions were introduced along the crystal's optic axis (c). A 9800 MHz electron paramagnetic resonance spectrum at room temperature, taken after room temperature X-irradiation, revealed the presence of a silver-compensated germanium center Asub(Ge-Ag) with large, almost isotropic 107 Ag and 109 Ag hyperfine splittings. Measurement of the spin-Hamiltonian discloses that a suitable model for the observed center utilizes germanium, substituted for silicon, with the accompanying silver interstitial in a nearby c-axis channel, and with electronic structure in which an appreciable admixture Ge 4+ - Ag 0 to Ge 3+ - Ag + exists. Estimates of the unpaired electron orbital are presented. (author)

  9. Silicon-germanium (Sige) nanostructures production, properties and applications in electronics

    CERN Document Server

    Usami, N

    2011-01-01

    Nanostructured silicon-germanium (SiGe) provides the prospect of novel and enhanced electronic device performance. This book reviews the materials science and technology of SiGe nanostructures, including crystal growth, fabrication of nanostructures, material properties and applications in electronics.$bNanostructured silicon-germanium (SiGe) opens up the prospects of novel and enhanced electronic device performance, especially for semiconductor devices. Silicon-germanium (SiGe) nanostructures reviews the materials science of nanostructures and their properties and applications in different electronic devices. The introductory part one covers the structural properties of SiGe nanostructures, with a further chapter discussing electronic band structures of SiGe alloys. Part two concentrates on the formation of SiGe nanostructures, with chapters on different methods of crystal growth such as molecular beam epitaxy and chemical vapour deposition. This part also includes chapters covering strain engineering and mo...

  10. Tensile strain mapping in flat germanium membranes

    International Nuclear Information System (INIS)

    Rhead, S. D.; Halpin, J. E.; Myronov, M.; Patchett, D. H.; Allred, P. S.; Wilson, N. R.; Leadley, D. R.; Shah, V. A.; Kachkanov, V.; Dolbnya, I. P.; Reparaz, J. S.; Sotomayor Torres, C. M.

    2014-01-01

    Scanning X-ray micro-diffraction has been used as a non-destructive probe of the local crystalline quality of a thin suspended germanium (Ge) membrane. A series of reciprocal space maps were obtained with ∼4 μm spatial resolution, from which detailed information on the strain distribution, thickness, and crystalline tilt of the membrane was obtained. We are able to detect a systematic strain variation across the membranes, but show that this is negligible in the context of using the membranes as platforms for further growth. In addition, we show evidence that the interface and surface quality is improved by suspending the Ge

  11. Tensile strain mapping in flat germanium membranes

    Energy Technology Data Exchange (ETDEWEB)

    Rhead, S. D., E-mail: S.Rhead@warwick.ac.uk; Halpin, J. E.; Myronov, M.; Patchett, D. H.; Allred, P. S.; Wilson, N. R.; Leadley, D. R. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Shah, V. A. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Department of Engineering, University of Warwick, Coventry, CV4 7AL (United Kingdom); Kachkanov, V.; Dolbnya, I. P. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE (United Kingdom); Reparaz, J. S. [ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain); Sotomayor Torres, C. M. [ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain)

    2014-04-28

    Scanning X-ray micro-diffraction has been used as a non-destructive probe of the local crystalline quality of a thin suspended germanium (Ge) membrane. A series of reciprocal space maps were obtained with ∼4 μm spatial resolution, from which detailed information on the strain distribution, thickness, and crystalline tilt of the membrane was obtained. We are able to detect a systematic strain variation across the membranes, but show that this is negligible in the context of using the membranes as platforms for further growth. In addition, we show evidence that the interface and surface quality is improved by suspending the Ge.

  12. Theoretical Investigations of the Hexagonal Germanium Carbonitride

    Directory of Open Access Journals (Sweden)

    Xinhai Yu

    2018-04-01

    Full Text Available The structural, mechanical, elastic anisotropic, and electronic properties of hexagonal germanium carbonitride (h-GeCN are systematically investigated using the first-principle calculations method with the ultrasoft pseudopotential scheme in the frame of generalized gradient approximation in the present work. The h-GeCN are mechanically and dynamically stable, as proved by the elastic constants and phonon spectra, respectively. The h-GeCN is brittle because the ratio B/G and Poisson’s ratio v of the h-GeCN are less than 1.75 and 0.26, respectively. For h-GeCN, from brittleness to ductility, the transformation pressures are 5.56 GPa and 5.63 GPa for B/G and Poisson’s ratio v, respectively. The h-GeCN exhibits the greater elastic anisotropy in Young’s modulus and the sound velocities. In addition, the calculated band structure of h-GeCN reveals that there is no band gap for h-GeCN with the HSE06 hybrid functional, so the h-GeCN is metallic.

  13. Cryogenic readout techniques for germanium detectors

    Energy Technology Data Exchange (ETDEWEB)

    Benato, G. [University of Zurich, (Switzerland); Cattadori, C. [INFN - Milano Bicocca, (Italy); Di Vacri, A. [INFN LNGS, (Italy); Ferri, E. [Universita Milano Bicocca/INFN Milano Bicocca, (Italy); D' Andrea, V.; Macolino, C. [GSSI/INFN LNGS, (Italy); Riboldi, S. [Universita degli Studi di Milano/INFN Milano, (Italy); Salamida, F. [Universita Milano Bicocca/INFN Milano Bicocca, (Italy)

    2015-07-01

    High Purity Germanium detectors are used in many applications, from nuclear and astro-particle physics, to homeland security or environment protection. Although quite standard configurations are often used, with cryostats, charge sensitive amplifiers and analog or digital acquisition systems all commercially available, it might be the case that a few specific applications, e.g. satellites, portable devices, cryogenic physics experiments, etc. also require the development of a few additional or complementary techniques. An interesting case is for sure GERDA, the Germanium Detector Array experiment, searching for neutrino-less double beta decay of {sup 76}Ge at the Gran Sasso National Laboratory of INFN - Italy. In GERDA the entire detector array, composed of semi-coaxial and BEGe naked crystals, is operated suspended inside a cryostat filled with liquid argon, that acts not only as cooling medium and but also as an active shield, thanks to its scintillation properties. These peculiar circumstances, together with the additional requirement of a very low radioactive background from all the materials adjacent to the detectors, clearly introduce significant constraints on the design of the Ge front-end readout electronics. All the Ge readout solutions developed within the framework of the GERDA collaboration, for both Phase I and Phase II, will be briefly reviewed, with their relative strength and weakness compared together and with respect to ideal Ge readout. Finally, the digital processing techniques developed by the GERDA collaboration for energy estimation of Ge detector signals will be recalled. (authors)

  14. Silicon-Germanium Front-End Electronics for Space-Based Radar Applications

    Data.gov (United States)

    National Aeronautics and Space Administration — Over the past two decades, Silicon-Germanium (SiGe) heterojunction bipolar transistor (HBT) technology has emerged as a strong platform for high-frequency...

  15. Fundamental aspects of nucleation and growth in the solution-phase synthesis of germanium nanocrystals

    KAUST Repository

    Codoluto, Stephen C.; Baumgardner, William J.; Hanrath, Tobias

    2010-01-01

    Colloidal Ge nanocrystals (NCs) were synthesized via the solution phase reduction of germanium(ii) iodide. We report a systematic investigation of the nanocrystal nucleation and growth as a function of synthesis conditions including the nature

  16. The germination of germanium

    Science.gov (United States)

    Burdette, Shawn C.; Thornton, Brett F.

    2018-02-01

    Shawn C. Burdette and Brett F. Thornton explore how germanium developed from a missing element in Mendeleev's periodic table to an enabler for the information age, while retaining a nomenclature oddity.

  17. Tunnel current across linear homocatenated germanium chains

    International Nuclear Information System (INIS)

    Matsuura, Yukihito

    2014-01-01

    The electronic transport properties of germanium oligomers catenating into linear chains (linear Ge chains) have been theoretically studied using first principle methods. The conduction mechanism of a Ge chain sandwiched between gold electrodes was analyzed based on the density of states and the eigenstates of the molecule in a two-probe environment. Like that of silicon chains (Si chains), the highest occupied molecular orbital of Ge chains contains the extended σ-conjugation of Ge 4p orbitals at energy levels close to the Fermi level; this is in contrast to the electronic properties of linear carbon chains. Furthermore, the conductance of a Ge chain is expected to decrease exponentially with molecular length L. The decay constant β, which is defined as e −βL , of a Ge chain is similar to that of a Si chain, whereas the conductance of the Ge chains is higher than that of Si chains even though the Ge–Ge bond length is longer than the Si–Si bond length

  18. 75 FR 1819 - GE-Hitachi Global Laser Enrichment LLC; (GLE Commercial Facility); Notice of Receipt of...

    Science.gov (United States)

    2010-01-13

    ... Energy Americas LLC (GEH), which is a wholly owned subsidiary of GE-Hitachi Nuclear Energy Holdings LLC..., 2009, the NRC published notice of its intent to prepare an Environmental Impact Statement (EIS) on the... on the issuance of a license is completed. See Notice of Intent to Prepare an Environmental Impact...

  19. Direct band gap electroluminescence from bulk germanium at room temperature using an asymmetric fin type metal/germanium/metal structure

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dong, E-mail: wang.dong.539@m.kyushu-u.ac.jp; Maekura, Takayuki; Kamezawa, Sho [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Yamamoto, Keisuke; Nakashima, Hiroshi [Art, Science and Technology Center for Cooperative Research, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan)

    2015-02-16

    We demonstrated direct band gap (DBG) electroluminescence (EL) at room temperature from n-type bulk germanium (Ge) using a fin type asymmetric lateral metal/Ge/metal structure with TiN/Ge and HfGe/Ge contacts, which was fabricated using a low temperature (<400 °C) process. Small electron and hole barrier heights were obtained for TiN/Ge and HfGe/Ge contacts, respectively. DBG EL spectrum peaked at 1.55 μm was clearly observed even at a small current density of 2.2 μA/μm. Superlinear increase in EL intensity was also observed with increasing current density, due to superlinear increase in population of elections in direct conduction band. The efficiency of hole injection was also clarified.

  20. Performance and stability tests of bare high purity germanium detectors in liquid argon for the GERDA experiment

    Energy Technology Data Exchange (ETDEWEB)

    Barnabe Heider, Marik

    2009-05-27

    GERDA will search for neutrinoless double beta decay of {sup 76}Ge by using a novel approach of bare germanium detectors in liquid argon (LAr). Enriched germanium detectors from the previous Heidelberg-Moscow and IGEX experiments have been reprocessed and will be deployed in GERDA Phase-I. At the center of this thesis project is the study of the performance of bare germanium detectors in cryogenic liquids. Identical detector performance as in vacuum cryostats (2.2 keV FWHM at 1.3 MeV) was achieved in cryogenic liquids with a new low-mass detector assembly and contacts. One major result is the discovery of a radiation induced leakage current (LC) increase when operating bare detectors with standard passivation layers in LAr. Charge collection and build-up on the passivation layer were identified as the origin of the LC increase. It was found that diodes without passivation do not exhibit this feature. Three month-long stable operation in LAr at {proportional_to} 5 pA LC under periodic gamma irradiation demonstrated the suitability of the modi ed detector design. Based on these results, all Phase-I detectors were reprocessed without passivation layer and subsequently successfully characterized in LAr in the GERDA underground Detector Laboratory. The mass loss during the reprocessing was {proportional_to}300 g out of 17.9 kg and the exposure above ground {proportional_to} 5 days. This results in a negligible cosmogenic background increase of {proportional_to} 5.10{sup -4} cts/(keV.kg.y) at {sup 76}Ge Q{sub {beta}}{sub {beta}} for {sup 60}Co and {sup 68}Ge. (orig.)

  1. Strain-induced changes to the electronic structure of germanium

    KAUST Repository

    Tahini, H. A.

    2012-04-17

    Density functional theory calculations (DFT) are used to investigate the strain-induced changes to the electronic structure of biaxially strained (parallel to the (001), (110) and (111) planes) and uniaxially strained (along the [001], [110] and [111] directions) germanium (Ge). It is calculated that a moderate uniaxial strain parallel to the [111] direction can efficiently transform Ge to a direct bandgap material with a bandgap energy useful for technological applications. © 2012 IOP Publishing Ltd.

  2. Strain-induced changes to the electronic structure of germanium

    KAUST Repository

    Tahini, H. A.; Chroneos, Alexander I.; Grimes, Robin W.; Schwingenschlö gl, Udo; Dimoulas, Athanasios Dimoulas

    2012-01-01

    Density functional theory calculations (DFT) are used to investigate the strain-induced changes to the electronic structure of biaxially strained (parallel to the (001), (110) and (111) planes) and uniaxially strained (along the [001], [110] and [111] directions) germanium (Ge). It is calculated that a moderate uniaxial strain parallel to the [111] direction can efficiently transform Ge to a direct bandgap material with a bandgap energy useful for technological applications. © 2012 IOP Publishing Ltd.

  3. Radiation-enhanced self- and boron diffusion in germanium

    DEFF Research Database (Denmark)

    Schneider, S.; Bracht, H.; Klug, J.N.

    2013-01-01

    We report experiments on proton radiation-enhanced self- and boron (B) diffusion in germanium (Ge) for temperatures between 515 ∘ C and 720 ∘ C. Modeling of the experimental diffusion profiles measured by means of secondary ion mass spectrometry is achieved on the basis of the Frenkel pair reaction...

  4. Precipitation of lithium in germanium

    International Nuclear Information System (INIS)

    Masaik, M.; Furgolle, B.

    1969-01-01

    The precipitation of Lithium in Germanium was studied. Taking account of the interactions Ga LI, LiO, we calculated the oxygen content in germanium samples from the resistivity measurements. (authors)

  5. Multistage hydrothermal silicification and Fe-Tl-As-Sb-Ge-REE enrichment in the Red Dog Zn-Pb-Ag district, northern Alaska: Geochemistry, origin, and exploration applications

    Science.gov (United States)

    Slack, J.F.; Kelley, K.D.; Anderson, V.M.; Clark, J.L.; Ayuso, R.A.

    2004-01-01

    Geochemical analyses of major, trace, and rare earth elements (REE) in more than 200 samples of variably silicified and altered wall rocks, massive and banded sulfide, silica rock, and sulfide-rich and unmineralized barite were obtained from the Main, Aqqaluk, and Anarraaq deposits in the Red Dog Zn-Pb-Ag district of northern Alaska. Detailed lithogeochemical profiles for two drill cores at Aqqaluk display an antithetic relationship between SiO2/Al2O3 and TiO2/Zr which, together with textural information, suggest preferential silicification of carbonate-bearing sediments. Data for both drill cores also show generally high Tl, Sb, As, and Ge and uniformly positive Eu anomalies (Eu/Eu* > 1.0). Similar high Tl, Sb, As, Ge, and Eu/Eu* values are present in the footwall and shallow hanging wall of Zn-Pb-Ag sulfide intervals at Anarraaq but are not as widely dispersed. Net chemical changes for altered wall rocks in the district, on the basis of average Al-normalized data relative to unaltered black shales of the host Kuna Formation, include large enrichments (>50%) of Fe, Ba, Eu, V, S, Co, Zn, Pb, Tl, As, Sb, and Ge at both Red Dog and Anarraaq, Si at Red Dog, and Sr, U, and Se at Anarraaq. Large depletions (>50%) are evident for Ca at both Red Dog and Anarraaq, for Mg, P, and Y at Red Dog, and for Na at Anarraaq. At both Red Dog and Anarraaq, wall-rock alteration removed calcite and minor dolomite during hydrothermal decarbonation reactions and introduced Si, Eu, and Ge during silicification. Sulfidation reactions deposited Fe, S, Co, Zn, Pb, Tl, As, and Sb; barite mineralization introduced Ba, S, and Sr. Light REE and U were mobilized locally. This alteration and mineralization occurred during Mississippi an hydrothermal events that predated the Middle Jurassic-Cretaceous Brookian orogeny. Early hydrothermal silicification at Red Dog took place prior to or during massive sulfide mineralization, on the basis of the dominantly planar nature of Zn-Pb veins, which suggests

  6. Pulse shape discrimination studies of Phase I Ge-detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kirsch, Andrea [MPI fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Collaboration: GERDA-Collaboration

    2013-07-01

    The GERmanium Detector Array experiment aims to search for the neutrinoless double beta decay (0νββ) of {sup 76}Ge by using isotopically enriched germanium crystals as source and detector simultaneously. The bare semiconductor diodes are operated in liquid argon at cryogenic temperatures in an ultra-low background environment. In addition, Gerda applies different active background reduction techniques, one of which is pulse shape discrimination studies of the current Phase I germanium detectors. The analysis of the signal time structure provides an important tool to distinguish single site events (SSE) of the ββ-decay from multi site events (MSE) of common gamma-ray background or surface events. To investigate the correlation between the signal shape and the interaction position, a new, also to the predominantly deployed closed-ended coaxial HPGe detectors applicable analysis technique has been developed. A summary of the used electronic/detector assembly is given and followed by a discussion of the performed classification procedure by means of accurate pulse shape simulations of 0νββ-like signals. Finally, the obtained results are presented along with an evaluation of the relevance for the Gerda experiment.

  7. Controllable growth of stable germanium dioxide ultra-thin layer by means of capacitively driven radio frequency discharge

    Energy Technology Data Exchange (ETDEWEB)

    Svarnas, P., E-mail: svarnas@ece.upatras.gr [High Voltage Laboratory, Department of Electrical and Computer Engineering, University of Patras, Rion 26 504, Patras (Greece); Botzakaki, M.A. [Department of Physics, University of Patras, Rion 26 504 (Greece); Skoulatakis, G.; Kennou, S.; Ladas, S. [Surface Science Laboratory, Department of Chemical Engineering, University of Patras, Rion 26 504 (Greece); Tsamis, C. [NCSR “Demokritos”, Institute of Advanced Materials, Physicochemical Processes, Nanotechnology & Microsystems, Aghia Paraskevi 15 310, Athens (Greece); Georga, S.N.; Krontiras, C.A. [Department of Physics, University of Patras, Rion 26 504 (Greece)

    2016-01-29

    It is well recognized that native oxide of germanium is hygroscopic and water soluble, while germanium dioxide is thermally unstable and it is converted to volatile germanium oxide at approximately 400 °C. Different techniques, implementing quite complicated plasma setups, gas mixtures and substrate heating, have been used in order to grow a stable germanium oxide. In the present work a traditional “RF diode” is used for germanium oxidation by cold plasma. Following growth, X-ray photoelectron spectroscopy demonstrates that traditional capacitively driven radio frequency discharges, using molecular oxygen as sole feedstock gas, provide the possibility of germanium dioxide layer growth in a fully reproducible and controllable manner. Post treatment ex-situ analyses on day-scale periods disclose the stability of germanium oxide at room ambient conditions, offering thus the ability to grow (ex-situ) ultra-thin high-k dielectrics on top of germanium oxide layers. Atomic force microscopy excludes any morphological modification in respect to the bare germanium surface. These results suggest a simple method for a controllable and stable germanium oxide growth, and contribute to the challenge to switch to high-k dielectrics as gate insulators for high-performance metal-oxide-semiconductor field-effect transistors and to exploit in large scale the superior properties of germanium as an alternative channel material in future technology nodes. - Highlights: • Simple one-frequency reactive ion etcher develops GeO{sub 2} thin layers controllably. • The layers remain chemically stable at ambient conditions over day-scale periods. • The layers are unaffected by the ex-situ deposition of high-k dielectrics onto them. • GeO{sub 2} oxidation and high-k deposition don't affect the Ge morphology significantly. • These conditions contribute to improved Ge-based MOS structure fabrication.

  8. Gold catalytic Growth of Germanium Nanowires by chemical vapour deposition method

    Directory of Open Access Journals (Sweden)

    M. Zahedifar

    2013-03-01

    Full Text Available Germanium nanowires (GeNWs were synthesized using chemical vapor deposition (CVD based on vapor–liquid–solid (VLS mechanism with Au nanoparticles as catalyst and germanium tetrachloride (GeCl4 as a precursor of germanium. Au catalysts were deposited on silicon wafer as a thin film, firstly by sputtering technique and secondly by submerging the silicon substrates in Au colloidal solution, which resulted in Au nanoparticles with different sizes. GeNWs were synthesized at 400 °C, which is a low temperature for electrical device fabrication. Effect of different parameters such as Au nanoparticles size, carrier gas (Ar flow and mixture of H2 with the carrier gas on GeNWs diameter and shape was studied by SEM images. The chemical composition of the nanostructure was also examined by energy dispersive X-ray spectroscopy (EDS.

  9. High performance germanium MOSFETs

    Energy Technology Data Exchange (ETDEWEB)

    Saraswat, Krishna [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States)]. E-mail: saraswat@stanford.edu; Chui, Chi On [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States); Krishnamohan, Tejas [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States); Kim, Donghyun [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States); Nayfeh, Ammar [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States); Pethe, Abhijit [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States)

    2006-12-15

    Ge is a very promising material as future channel materials for nanoscale MOSFETs due to its high mobility and thus a higher source injection velocity, which translates into higher drive current and smaller gate delay. However, for Ge to become main-stream, surface passivation and heterogeneous integration of crystalline Ge layers on Si must be achieved. We have demonstrated growth of fully relaxed smooth single crystal Ge layers on Si using a novel multi-step growth and hydrogen anneal process without any graded buffer SiGe layer. Surface passivation of Ge has been achieved with its native oxynitride (GeO {sub x}N {sub y} ) and high-permittivity (high-k) metal oxides of Al, Zr and Hf. High mobility MOSFETs have been demonstrated in bulk Ge with high-k gate dielectrics and metal gates. However, due to their smaller bandgap and higher dielectric constant, most high mobility materials suffer from large band-to-band tunneling (BTBT) leakage currents and worse short channel effects. We present novel, Si and Ge based heterostructure MOSFETs, which can significantly reduce the BTBT leakage currents while retaining high channel mobility, making them suitable for scaling into the sub-15 nm regime. Through full band Monte-Carlo, Poisson-Schrodinger and detailed BTBT simulations we show a dramatic reduction in BTBT and excellent electrostatic control of the channel, while maintaining very high drive currents in these highly scaled heterostructure DGFETs. Heterostructure MOSFETs with varying strained-Ge or SiGe thickness, Si cap thickness and Ge percentage were fabricated on bulk Si and SOI substrates. The ultra-thin ({approx}2 nm) strained-Ge channel heterostructure MOSFETs exhibited >4x mobility enhancements over bulk Si devices and >10x BTBT reduction over surface channel strained SiGe devices.

  10. High performance germanium MOSFETs

    International Nuclear Information System (INIS)

    Saraswat, Krishna; Chui, Chi On; Krishnamohan, Tejas; Kim, Donghyun; Nayfeh, Ammar; Pethe, Abhijit

    2006-01-01

    Ge is a very promising material as future channel materials for nanoscale MOSFETs due to its high mobility and thus a higher source injection velocity, which translates into higher drive current and smaller gate delay. However, for Ge to become main-stream, surface passivation and heterogeneous integration of crystalline Ge layers on Si must be achieved. We have demonstrated growth of fully relaxed smooth single crystal Ge layers on Si using a novel multi-step growth and hydrogen anneal process without any graded buffer SiGe layer. Surface passivation of Ge has been achieved with its native oxynitride (GeO x N y ) and high-permittivity (high-k) metal oxides of Al, Zr and Hf. High mobility MOSFETs have been demonstrated in bulk Ge with high-k gate dielectrics and metal gates. However, due to their smaller bandgap and higher dielectric constant, most high mobility materials suffer from large band-to-band tunneling (BTBT) leakage currents and worse short channel effects. We present novel, Si and Ge based heterostructure MOSFETs, which can significantly reduce the BTBT leakage currents while retaining high channel mobility, making them suitable for scaling into the sub-15 nm regime. Through full band Monte-Carlo, Poisson-Schrodinger and detailed BTBT simulations we show a dramatic reduction in BTBT and excellent electrostatic control of the channel, while maintaining very high drive currents in these highly scaled heterostructure DGFETs. Heterostructure MOSFETs with varying strained-Ge or SiGe thickness, Si cap thickness and Ge percentage were fabricated on bulk Si and SOI substrates. The ultra-thin (∼2 nm) strained-Ge channel heterostructure MOSFETs exhibited >4x mobility enhancements over bulk Si devices and >10x BTBT reduction over surface channel strained SiGe devices

  11. Calibration of germanium detectors

    International Nuclear Information System (INIS)

    Bjurman, B.; Erlandsson, B.

    1985-01-01

    This paper describes problems concerning the calibration of germanium detectors for the measurement of gamma-radiation from environmental samples. It also contains a brief description of some ways of reducing the uncertainties concerning the activity determination. These uncertainties have many sources, such as counting statistics, full energy peak efficiency determination, density correction and radionuclide specific-coincidence effects, when environmental samples are investigated at close source-to-detector distances

  12. Determination of the Wetting Angle of Germanium and Germanium-Silicon Melts on Different Substrate Materials

    Science.gov (United States)

    Kaiser, Natalie; Croell, Arne; Szofran, F. R.; Cobb. S. D.; Dold, P.; Benz, K. W.

    1999-01-01

    During Bridgman growth of semiconductors detachment of the crystal and the melt meniscus has occasionally been observed, mainly under microgravity (microg) conditions. An important factor for detached growth is the wetting angle of the melt with the crucible material. High contact angles are more likely to result in detachment of the growing crystal from the ampoule wall. In order to achieve detached growth of germanium (Ge) and germanium-silicon (GeSi) crystals under 1g and microg conditions, sessile drop measurements were performed to determine the most suitable ampoule material as well as temperature dependence of the surface tension for GeSi. Sapphire, fused quartz, glassy carbon, graphite, SiC, pyrolytic Boron Nitride (pBN), AIN, and diamond were used as substrates. Furthermore, different cleaning procedures and surface treatments (etching, sandblasting, etc.) of the same substrate material and their effect on the wetting behavior were studied during these experiments. pBN and AIN substrates exhibited the highest contact angles with values around 170 deg.

  13. Synthesis and evaluation of germanium organometallic compounds as precursors for chemical vapor deposition (CVD) and for obtaining nanoparticles of elemental germanium

    International Nuclear Information System (INIS)

    Ballestero Martinez, Ernesto

    2014-01-01

    The interest in the development of materials having applications such as electronics areas or biomarkers has affected the synthesis of new compounds based on germanium. This element has had two common oxidation states, +4 and +2, of them, +2 oxidation state has been the least studied and more reactive. Additionally, compounds of germanium (II) have had similarities with carbenes regarding the chemical acid-base Lewis. The preparation of compounds of germanium (II) with ligands β-decimations has enabled stabilization of new chemical functionalities and, simultaneously, provided interesting thermal properties to develop new preparation methodologies of materials with novel properties. The preparation of amides germanium(II) L'Ge(NHPh) [1, L' = {HC (CMeN-2,4,6-Me 3 C 6 H 2 ) 2 }], L'Ge(4-NHPy) [2] L'Ge(2-NHPy) [3] and LGe(2-NHPy) [4, L = {HC(CMeN-2,6- i Pr 2 C 6 H 3 ) 2 }]; the structural chemical composition were determined using techniques such as nuclear magnetic resonance ( 1 H, 13 C), other techniques are treated: elemental analysis, melting point, infrared spectroscopy, X-ray diffraction of single crystal and thermal gravimetric analysis (TGA). The TGA has showed that 4-1 have experimented a thermal decomposition; therefore, these compounds could be considered as potential starting materials for obtaining germanium nitride (GeN x ). Certainly, the availability of nitrogen coordinating atoms in the chemical composition in 2-4 have been interesting because it could act as ligands in reactions with transition metal complexes. That way, information could be obtained at the molecular level for some reactions and interactions that in surface chemistry have used similar link sites, for example, chemical functionalization of silicon and germanium substrates. The synthesis and structural characterization of germanium chloride compound(II) L''GeCl [5, L'' = HC{(CMe) (N-2,6-Me 2 C 6 H 3 )} 2 ], which could be used later for the

  14. Nanorods of Silicon and Germanium with Well-Defined Shapes and Sizes

    Energy Technology Data Exchange (ETDEWEB)

    Slavi C. Sevov

    2012-05-03

    We have made number of important discoveries along the major goals of the project, namely i) electrodeposition of germanium thin films from clusters, ii) synthesis of cluster-based surfactants with long hydrocarbon chains and micelles made of them, iii) grafting of Ge{sub 9}-clusters onto self assembled films of siloxanes attached to glass substrates, iv) doping of Ge{sub 9}-clusters, and v) expanding the clusters to ten-atom cages of Ge{sub 10}{sup 2-}.

  15. Optical properties of Germanium nanoparticles synthesized by pulsed laser ablation in acetone

    Directory of Open Access Journals (Sweden)

    Saikiran eVadavalli

    2014-10-01

    Full Text Available Germanium (Ge nanoparticles (NPs are synthesized by means of pulsed laser ablation of bulk germanium target immersed in acetone with ns laser pulses at different pulse energies. The fabricated NPs are characterized by employing different techniques such as UV-visible absorption spectroscopy, photoluminescence, micro-Raman spectroscopy, transmission electron microscopy (TEM and field emission scanning electron microscopy (FESEM. The mean size of the Ge NPs is found to vary from few nm to 40 nm with the increase in laser pulse energy. Shift in the position of the absorption spectra is observed and also the photoluminescence peak shift is observed due to quantum confinement effects. High resolution TEM combined with micro-Raman spectroscopy confirms the crystalline nature of the generated germanium nanoparticles. The formation of various sizes of germanium NPs at different laser pulse energies is evident from the asymmetry in the Raman spectra and the shift in its peak position towards the lower wavenumber side. The FESEM micrographs confirm the formation of germanium micro/nanostructures at the laser ablated position of the bulk germanium. In particular, the measured NP sizes from the micro-Raman phonon quantum confinement model are found in good agreement with TEM measurements of Ge NPs.

  16. Influence of reductant and germanium concentration on the growth and stress development of germanium nanocrystals in silicon oxide matrix

    International Nuclear Information System (INIS)

    Chew, H G; Zheng, F; Choi, W K; Chim, W K; Foo, Y L; Fitzgerald, E A

    2007-01-01

    Germanium (Ge) nanocrystals have been synthesized by annealing co-sputtered SiO 2 -Ge samples in N 2 or forming gas (90% N 2 +10% H 2 ) at temperatures ranging from 700 to 1000 deg. C. We concluded that the annealing ambient, temperature and Ge concentration have a significant influence on the formation and evolution of the nanocrystals. We showed that a careful selective etching of the annealed samples in hydrofluoric acid solution enabled the embedded Ge nanocrystals to be liberated from the SiO 2 matrix. From the Raman results of the as-grown and the liberated nanocrystals, we established that the nanocrystals generally experienced compressive stress in the oxide matrix and the evolution of these stress states was intimately linked to the distribution, density, size and quality of the Ge nanocrystals

  17. Event timing in high purity germanium coaxial detectors

    International Nuclear Information System (INIS)

    El-Ibiary, M.Y.

    1979-08-01

    The timing of gamma ray radiation in systems using high purity coaxial germanium detectors is analyzed and compared to that of systems using Ge(Li) detectors. The analysis takes into account the effect of the residual impurities on the electric field distribution, and hence on the rate of rise of the electrical pulses delivered to the timing module. Conditions under which the electric field distribution could lead to an improvement in timing performance, are identified. The results of the analysis confirm the experimental results published elsewhere and when compared with those for Ge(Li) detectors, which usually operate under conditions of charge carrier velocity saturation, confirm that high purity germanium detectors need not have inferior timing characteristics. A chart is given to provide a quantitative basis on which the trade off between the radius of the detector and its time resolution may be made

  18. Germanium-doped gallium phosphide obtained by neutron irradiation

    Science.gov (United States)

    Goldys, E. M.; Barczynska, J.; Godlewski, M.; Sienkiewicz, A.; Heijmink Liesert, B. J.

    1993-08-01

    Results of electrical, optical, electron spin resonance and optically detected magnetic resonance studies of thermal neutron irradiated and annealed at 800 °C n-type GaP are presented. Evidence is found to support the view that the main dopant introduced via transmutation of GaP, germanium, occupies cation sites and forms neutral donors. This confirms the possibility of neutron transmutation doping of GaP. Simultaneously, it is shown that germanium is absent at cation sites. Presence of other forms of Ge-related defects is deduced from luminescence and absorption data. Some of them are tentatively identified as VGa-GeGa acceptors leading to the self-compensation process. This observation means that the neutron transmutation as a doping method in application to GaP is not as efficient as for Si.

  19. Reduction of Defects in Germanium-Silicon

    Science.gov (United States)

    2003-01-01

    Crystals grown without contact with a container have far superior quality to otherwise similar crystals grown in direct contact with a container. In addition to float-zone processing, detached- Bridgman growth is a promising tool to improve crystal quality, without the limitations of float zoning or the defects introduced by normal Bridgman growth. Goals of this project include the development of the detached Bridgman process to be reproducible and well understood and to quantitatively compare the defect and impurity levels in crystals grown by these three methods. Germanium (Ge) and germanium-silicon (Ge-Si) alloys are being used. At MSFC, we are responsible for the detached Bridgman experiments intended to differentiate among proposed mechanisms of detachment, and to confirm or refine our understanding of detachment. Because the contact angle is critical to determining the conditions for detachment, the sessile drop method was used to measure the contact angles as a function of temperature and composition for a large number of substrates made of potential ampoule materials. Growth experiments have used pyrolytic boron nitride (pBN) and fused silica ampoules with the majority of the detached results occurring predictably in the pBN. Etch pit density (EPD) measurements of normal and detached Bridgman-grown Ge samples show a two order of magnitude improvement in the detached-grown samples. The nature and extent of detachment is determined by using profilometry in conjunction with optical and electron microscopy. The stability of detachment has been analyzed, and an empirical model for the conditions necessary to achieve sufficient stability to maintain detached growth for extended periods has been developed. We have investigated the effects on detachment of ampoule material, pressure difference above and below the melt, and Si concentration; samples that are nearly completely detached can be grown repeatedly in pBN. Current work is concentrated on developing a

  20. Nb3Ge superconductive films grown with nitrogen

    International Nuclear Information System (INIS)

    Sigsbee, R.A.

    1978-01-01

    A superconductive film of Nb 3 Ge is produced by providing within a vacuum chamber a heated substrate and sources of niobium and germanium, reducing the pressure within the chamber to a residual pressure no greater than about 10 -5 mm Hg, introducing nitrogen into the resulting evacuated chamber in controlled amounts and vaporizing the niobium and germanium to deposit a film of Nb 3 Ge on the heated substrate

  1. Diffusion of tin in germanium: A GGA+U approach

    KAUST Repository

    Tahini, H. A.; Chroneos, Alexander; Grimes, R. W.; Schwingenschlö gl, Udo

    2011-01-01

    Density functional theory calculations are used to investigate the formation and diffusion of tin-vacancy pairs (SnV) in germanium(Ge). Depending upon the Fermi energy, SnV pairs can form in neutral, singly negative, or doubly negative charged states. The activation energies of diffusion, also as function of the Fermi energy, are calculated to lie between 2.48-3.65 eV, in agreement with and providing an interpretation of available experimental work.

  2. Diffusion of tin in germanium: A GGA+U approach

    KAUST Repository

    Tahini, H. A.

    2011-10-18

    Density functional theory calculations are used to investigate the formation and diffusion of tin-vacancy pairs (SnV) in germanium(Ge). Depending upon the Fermi energy, SnV pairs can form in neutral, singly negative, or doubly negative charged states. The activation energies of diffusion, also as function of the Fermi energy, are calculated to lie between 2.48-3.65 eV, in agreement with and providing an interpretation of available experimental work.

  3. The Majorana Demonstrator: A search for neutrinoless double-beta decay of germanium-76

    Science.gov (United States)

    Elliott, S. R.; Abgrall, N.; Aguayo, E.; Avignone, F. T., III; Barabash, A. S.; Bertrand, F. E.; Boswell, M.; Brudanin, V.; Busch, M.; Caldwell, A. S.; Chan, Y.-D.; Christofferson, C. D.; Combs, D. C.; Detwiler, J. A.; Doe, P. J.; Efremenko, Yu.; Egorov, V.; Ejiri, H.; Esterline, J.; Fast, J. E.; Finnerty, P.; Fraenkle, F. M.; Galindo-Uribarri, A.; Giovanetti, G. K.; Goett, J.; Green, M. P.; Gruszko, J.; Guiseppe, V. E.; Gusev, K.; Hallin, A. L.; Hazama, R.; Hegai, A.; Henning, R.; Hoppe, E. W.; Howard, S.; Howe, M. A.; Keeter, K. J.; Kidd, M. F.; Kochetov, O.; Konovalov, S. I.; Kouzes, R. T.; LaFerriere, B. D.; Leon, J.; Leviner, L. E.; Loach, J. C.; MacMullin, S.; Martin, R. D.; Mertens, S.; Mizouni, L.; Nomachi, M.; Orrell, J. L.; O'Shaughnessy, C.; Overman, N. R.; Phillips, D. G., II; Poon, A. W. P.; Pushkin, K.; Radford, D. C.; Rielage, K.; Robertson, R. G. H.; Ronquest, M. C.; Schubert, A. G.; Shanks, B.; Shima, T.; Shirchenko, M.; Snavely, K. J.; Snyder, N.; Soin, A.; Strain, J.; Suriano, A. M.; Timkin, V.; Tornow, W.; Varner, R. L.; Vasilyev, S.; Vetter, K.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Xu, W.; Yakushev, E.; Young, A. R.; Yu, C.-H.; Yumatov, V.

    2013-12-01

    The Majorana collaboration is searching for neutrinoless double beta decay using 76Ge, which has been shown to have a number of advantages in terms of sensitivities and backgrounds. The observation of neutrinoless double-beta decay would show that lepton number is violated and that neutrinos are Majorana particles and would simultaneously provide information on neutrino mass. Attaining sensitivities for neutrino masses in the inverted hierarchy region, 15 - 50 meV, will require large, tonne-scale detectors with extremely low backgrounds, at the level of ˜1 count/t-y or lower in the region of the signal. The Majorana collaboration, with funding support from DOE Office of Nuclear Physics and NSF Particle Astrophysics, is constructing the Demonstrator, an array consisting of 40 kg of p-type point-contact high-purity germanium (HPGe) detectors, of which ˜30 kg will be enriched to 87% in 76Ge. The Demonstrator is being constructed in a clean room laboratory facility at the 4850' level (4300 m.w.e.) of the Sanford Underground Research Facility (SURF) in Lead, SD. It utilizes a compact graded shield approach with the inner portion consisting of ultra-clean Cu that is being electroformed and machined underground. The primary aim of the Demonstrator is to show the feasibility of a future tonne-scale measurement in terms of backgrounds and scalability.

  4. Influence of varying Germanium content on the optical function dispersion of Fe{sub 2}MnSi{sub x}Ge{sub 1-x}: An ab initio study

    Energy Technology Data Exchange (ETDEWEB)

    Reshak, Ali H., E-mail: maalidph@yahoo.co.uk [School of Complex Systems, FFPW, CENAKVA, University of South Bohemia in CB, Nove Hrady 37333 (Czech Republic); School of Material Engineering, Malaysia University of Perlis, P.O. Box 77, d/a Pejabat Pos Besar, 01007 Kangar, Perlis (Malaysia); Charifi, Z., E-mail: charifizoulikha@gmail.com [Physics Department, Faculty of Science, University of M' sila, 28000 M' sila (Algeria); Baaziz, H. [Physics Department, Faculty of Science, University of M' sila, 28000 M' sila (Algeria)

    2013-01-15

    The optical dielectric functions of Fe{sub 2}MnSi{sub 1-x}Ge{sub x} alloys for selected concentrations (x=0.0, 0.25, 0.5, 0.75 and 1.0) were investigated. The ferromagnetic Fe{sub 2}MnSi{sub x}Ge{sub 1-x} is semiconducting with optical band gaps 0.507, 0.531, 0.539, 0.514 and 0.547 eV for the minority spin and is metallic for the majority spin. From the calculated results the half-metallic character and stability of ferromagnetic state for Fe{sub 2}MnSi{sub x}Ge{sub 1-x} is determined. The total magnetic moment is found to be 3.0{mu}{sub B} for all alloys with the most contribution from Mn local magnetic moments. Iron atoms however exhibit much smaller spin moments, about 10% of the bulk value, and the sp atoms have induced magnetic moments due to the proximity of Fe first nearest neighbors, which couple antiferromagnetically with Fe and Mn spin moments. We have employed full-potential linearized augmented plane wave method based on spin-polarized density functional theory. The generalized gradient approximation exchange-correlation potential was used. The edge of optical absorption for {epsilon}{sub 2}({omega}) of spin-down varies between 0.507 (Fe{sub 2}MnGe) and 0.547 eV (Fe{sub 2}MnSi). Since the spin-up shows metallic nature, the Drude term was included in the spin-up optical dielectric functions. This confirms our finding that these materials are half-metallic. Furthermore, the reflectivity, refractivity and the absorption coefficient were calculated. These results show that the materials possess half-metallic character. - Highlights: Black-Right-Pointing-Pointer The optical dielectric functions of Fe{sub 2}MnSi{sub 1-x}Ge{sub x} were investigated. Black-Right-Pointing-Pointer Fe{sub 2}MnSi{sub x}Ge{sub 1-x} is semiconducting for majority spin and is metallic for minority spin. Black-Right-Pointing-Pointer The total magnetic moment is found to be 3.0{mu}{sub B} for all alloys. Black-Right-Pointing-Pointer The edge of optical absorption for {epsilon}{sub 2

  5. Bibliographical study on the high-purity germanium radiation detectors used in gamma and X spectrometry

    International Nuclear Information System (INIS)

    Bornand, Bernard; Friant, Alain

    1979-03-01

    The germanium or silicon lithium-drifted detectors, Ge(Li) or Si(Li), and high-purity germanium detectors, HP Ge (impurity concentration approximately 10 10 cm -3 ), are the most commonly used at the present time as gamma and X-ray spectrometers. The HP Ge detectors for which room temperature storage is the main characteristic can be obtained with a large volume and a thin window, and are used as the Ge(Li) in γ ray spectrometry or the Si(Li) in X-ray spectrometry. This publication reviews issues from 1974 to 1978 on the state of the art and applications of the HP Ge semiconductor detectors. 101 bibliographical notices with French summaries are presented. An index for authors, documents and periodicals, and subjects is included [fr

  6. Thermal stability of simple tetragonal and hexagonal diamond germanium

    Science.gov (United States)

    Huston, L. Q.; Johnson, B. C.; Haberl, B.; Wong, S.; Williams, J. S.; Bradby, J. E.

    2017-11-01

    Exotic phases of germanium, that form under high pressure but persist under ambient conditions, are of technological interest due to their unique optical and electrical properties. The thermal evolution and stability of two of these exotic Ge phases, the simple tetragonal (st12) and hexagonal diamond (hd) phases, are investigated in detail. These metastable phases, formed by high pressure decompression in either a diamond anvil cell or by nanoindentation, are annealed at temperatures ranging from 280 to 320 °C for st12-Ge and 200 to 550 °C for hd-Ge. In both cases, the exotic phases originated from entirely pure Ge precursor materials. Raman microspectroscopy is used to monitor the phase changes ex situ following annealing. Our results show that hd-Ge synthesized via a pure form of a-Ge first undergoes a subtle change in structure and then an irreversible phase transformation to dc-Ge with an activation energy of (4.3 ± 0.2) eV at higher temperatures. St12-Ge was found to transform to dc-Ge with an activation energy of (1.44 ± 0.08) eV. Taken together with results from previous studies, this study allows for intriguing comparisons with silicon and suggests promising technological applications.

  7. Etching of germanium-tin using ammonia peroxide mixture

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Yuan; Ong, Bin Leong; Wang, Wei; Gong, Xiao; Liang, Gengchiau; Yeo, Yee-Chia, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Zhang, Zheng; Pan, Jisheng [Institute of Material Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, #08-03, Innovis, Singapore 138634 (Singapore); Tok, Eng-Soon [Department of Physics, National University of Singapore, Singapore 117551 (Singapore)

    2015-12-28

    The wet etching of germanium-tin (Ge{sub 1-x}Sn{sub x}) alloys (4.2% < x < 16.0%) in ammonia peroxide mixture (APM) is investigated. Empirical fitting of the data points indicates that the etch depth of Ge{sub 1-x}Sn{sub x} is proportional to the square root of the etch time t and decreases exponentially with increasing x for a given t. In addition, X-ray photoelectron spectroscopy results show that increasing t increases the intensity of the Sn oxide peak, whereas no obvious change is observed for the Ge oxide peak. This indicates that an accumulation of Sn oxide on the Ge{sub 1-x}Sn{sub x} surface decreases the amount of Ge atoms exposed to the etchant, which accounts for the decrease in etch rate with increasing etch time. Atomic force microscopy was used to examine the surface morphologies of the Ge{sub 0.918}Sn{sub 0.082} samples. Both root-mean-square roughness and undulation periods of the Ge{sub 1-x}Sn{sub x} surface were observed to increase with increasing t. This work provides further understanding of the wet etching of Ge{sub 1-x}Sn{sub x} using APM and may be used for the fabrication of Ge{sub 1-x}Sn{sub x}-based electronic and photonic devices.

  8. Tunable conductivity in mesoporous germanium

    Science.gov (United States)

    Beattie, Meghan N.; Bioud, Youcef A.; Hobson, David G.; Boucherif, Abderraouf; Valdivia, Christopher E.; Drouin, Dominique; Arès, Richard; Hinzer, Karin

    2018-05-01

    Germanium-based nanostructures have attracted increasing attention due to favourable electrical and optical properties, which are tunable on the nanoscale. High densities of germanium nanocrystals are synthesized via electrochemical etching, making porous germanium an appealing nanostructured material for a variety of applications. In this work, we have demonstrated highly tunable electrical conductivity in mesoporous germanium layers by conducting a systematic study varying crystallite size using thermal annealing, with experimental conductivities ranging from 0.6 to 33 (×10‑3) Ω‑1 cm‑1. The conductivity of as-prepared mesoporous germanium with 70% porosity and crystallite size between 4 and 10 nm is shown to be ∼0.9 × 10‑3 Ω‑1 cm‑1, 5 orders of magnitude smaller than that of bulk p-type germanium. Thermal annealing for 10 min at 400 °C further reduced the conductivity; however, annealing at 450 °C caused a morphological transformation from columnar crystallites to interconnecting granular crystallites and an increase in conductivity by two orders of magnitude relative to as-prepared mesoporous germanium caused by reduced influence of surface states. We developed an electrostatic model relating the carrier concentration and mobility of p-type mesoporous germanium to the nanoscale morphology. Correlation within an order of magnitude was found between modelled and experimental conductivities, limited by variation in sample uniformity and uncertainty in void size and fraction after annealing. Furthermore, theoretical results suggest that mesoporous germanium conductivity could be tuned over four orders of magnitude, leading to optimized hybrid devices.

  9. Detached Bridgman Growth of Germanium and Germanium-Silicon Alloy Crystals

    Science.gov (United States)

    Szofran, F. R.; Volz, M. P.; Schweizer, M.; Cobb, S. D.; Motakef, S.; Croell, A.; Dold, P.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Earth based experiments on the science of detached crystal growth are being conducted on germanium and germanium-silicon alloys (2 at% Si average composition) in preparation for a series of experiments aboard the International Space Station (ISS). The purpose of the microgravity experiments includes differentiating among proposed mechanisms contributing to detachment, and confirming or refining our understanding of the detachment mechanism. Because large contact angle are critical to detachment, sessile drop measurements were used to determine the contact angles as a function of temperature and composition for a large number of substrates made of potential ampoule materials. Growth experiments have used pyrolytic boron nitride (pBN) and fused silica ampoules with the majority of the detached results occurring predictably in the pBN. The contact angles were 173 deg (Ge) and 165 deg (GeSi) for pBN. For fused silica, the contact angle decreases from 150 deg to an equilibrium value of 117 deg (Ge) or from 129 deg to an equilibrium value of 100 deg (GeSi) over the duration of the experiment. The nature and extent of detachment is determined by using profilometry in conjunction with optical and electron microscopy. The stability of detachment has been analyzed, and an empirical model for the conditions necessary to achieve sufficient stability to maintain detached growth for extended periods has been developed. Results in this presentation will show that we have established the effects on detachment of ampoule material, pressure difference above and below the melt, and silicon concentration; samples that are nearly completely detached can be grown repeatedly in pBN.

  10. New hydrogen donors in germanium

    International Nuclear Information System (INIS)

    Pokotilo, Yu.M.; Petukh, A.N.; Litvinov, V.V.

    2003-01-01

    The electrophysical properties of the n-type conductivity germanium, irradiated through protons, is studied by the volt-farad method. It is shown that the heat treatment of the implanted germanium at the temperature of 200-300 deg C leads to formation of the fast-diffusing second-rate donors. It is established that the diffusion coefficient of the identified donors coincides with the diffusion coefficient of the atomic hydrogen with an account of the capture on the traps. The conclusion is made, that the atomic hydrogen is the second-rate donor center in germanium [ru

  11. Ge interactions on HfO2 surfaces and kinetically driven patterning of Ge nanocrystals on HfO2

    International Nuclear Information System (INIS)

    Stanley, Scott K.; Joshi, Sachin V.; Banerjee, Sanjay K.; Ekerdt, John G.

    2006-01-01

    Germanium interactions are studied on HfO 2 surfaces, which are prepared through physical vapor deposition (PVD) and by atomic layer deposition. X-ray photoelectron spectroscopy and temperature-programed desorption are used to follow the reactions of germanium on HfO 2 . Germanium chemical vapor deposition at 870 K on HfO 2 produces a GeO x adhesion layer, followed by growth of semiconducting Ge 0 . PVD of 0.7 ML Ge (accomplished by thermally cracking GeH 4 over a hot filament) also produces an initial GeO x layer, which is stable up to 800 K. PVD above 2.0 ML deposits semiconducting Ge 0 . Temperature programed desorption experiments of ∼1.0 ML Ge from HfO 2 at 400-1100 K show GeH 4 desorption below 600 K and GeO desorption above 850 K. These results are compared to Ge on SiO 2 where GeO desorption is seen at 550 K. Exploiting the different reactivity of Ge on HfO 2 and SiO 2 allows a kinetically driven patterning scheme for high-density Ge nanoparticle growth on HfO 2 surfaces that is demonstrated

  12. One-step Ge/Si epitaxial growth.

    Science.gov (United States)

    Wu, Hung-Chi; Lin, Bi-Hsuan; Chen, Huang-Chin; Chen, Po-Chin; Sheu, Hwo-Shuenn; Lin, I-Nan; Chiu, Hsin-Tien; Lee, Chi-Young

    2011-07-01

    Fabricating a low-cost virtual germanium (Ge) template by epitaxial growth of Ge films on silicon wafer with a Ge(x)Si(1-x) (0 deposition method in one step by decomposing a hazardousless GeO(2) powder under hydrogen atmosphere without ultra-high vacuum condition and then depositing in a low-temperature region. X-ray diffraction analysis shows that the Ge film with an epitaxial relationship is along the in-plane direction of Si. The successful growth of epitaxial Ge films on Si substrate demonstrates the feasibility of integrating various functional devices on the Ge/Si substrates.

  13. 1-Dodecanethiol based highly stable self-assembled monolayers for germanium passivation

    International Nuclear Information System (INIS)

    Cai, Qi; Xu, Baojian; Ye, Lin; Di, Zengfeng; Huang, Shanluo; Du, Xiaowei; Zhang, Jishen; Jin, Qinghui; Zhao, Jianlong

    2015-01-01

    Highlights: • A simple and effective approach for higly stable germanium passivation. • 1-Dodecanethiol self-assembled monolayers for germanium oxidation resistance. • The influence factors of germanium passivation were systematically studied. • The stability of the passivated Ge was more than 10 days even in water conditions. - Abstract: As a typical semiconductor material, germanium has the potential to replace silicon for future-generation microelectronics, due to its better electrical properties. However, the lack of stable surface state has limited its extensive use for several decades. In this work, we demonstrated highly stable self-assembled monolayers (SAMs) on Ge surface to prevent oxidization for further applications. After the pretreatment in hydrochloric acid, the oxide-free and Cl-terminated Ge could be further coated with 1-dodecanethiol (NDM) SAMs. The influence factors including reaction time, solvent component and reaction temperature were optimized to obtain stable passivated monolayer for oxidation resistance. Contact angle analysis, atomic force microscopy, ellipsometer and X-ray photoelectron spectroscopy were performed to characterize the functionalized Ge surface respectively. Meanwhile, the reaction mechanism and stability of thiols SAMs on Ge (1 1 1) surface were investigated. Finally, highly stable passivated NDM SAMs on Ge surface could be formed through immersing oxide-free Ge in mixture solvent (water/ethanol, v/v = 1:1) at appropriately elevated temperature (∼80 °C) for 24 h. And the corresponding optimized passivated Ge surface was stable for more than 10 days even in water condition, which was much longer than the data reported and paved the way for the future practical applications of Ge.

  14. 1-Dodecanethiol based highly stable self-assembled monolayers for germanium passivation

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Qi [State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No. 865, Changning Road, Shanghai 200050 (China); University of Chinese Academy of Sciences, No. 19A, Yuquan Road, Beijing 100049 (China); Xu, Baojian, E-mail: xbj@mail.sim.ac.cn [State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No. 865, Changning Road, Shanghai 200050 (China); Shanghai Internet of Things Co., LTD, No. 1455, Pingcheng Road, Shanghai 201899 (China); Ye, Lin [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No. 865, Changning Road, Shanghai 200050 (China); University of Chinese Academy of Sciences, No. 19A, Yuquan Road, Beijing 100049 (China); Di, Zengfeng [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No. 865, Changning Road, Shanghai 200050 (China); Huang, Shanluo; Du, Xiaowei [State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No. 865, Changning Road, Shanghai 200050 (China); University of Chinese Academy of Sciences, No. 19A, Yuquan Road, Beijing 100049 (China); Zhang, Jishen; Jin, Qinghui [State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No. 865, Changning Road, Shanghai 200050 (China); Zhao, Jianlong, E-mail: jlzhao@mail.sim.ac.cn [State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No. 865, Changning Road, Shanghai 200050 (China)

    2015-10-30

    Highlights: • A simple and effective approach for higly stable germanium passivation. • 1-Dodecanethiol self-assembled monolayers for germanium oxidation resistance. • The influence factors of germanium passivation were systematically studied. • The stability of the passivated Ge was more than 10 days even in water conditions. - Abstract: As a typical semiconductor material, germanium has the potential to replace silicon for future-generation microelectronics, due to its better electrical properties. However, the lack of stable surface state has limited its extensive use for several decades. In this work, we demonstrated highly stable self-assembled monolayers (SAMs) on Ge surface to prevent oxidization for further applications. After the pretreatment in hydrochloric acid, the oxide-free and Cl-terminated Ge could be further coated with 1-dodecanethiol (NDM) SAMs. The influence factors including reaction time, solvent component and reaction temperature were optimized to obtain stable passivated monolayer for oxidation resistance. Contact angle analysis, atomic force microscopy, ellipsometer and X-ray photoelectron spectroscopy were performed to characterize the functionalized Ge surface respectively. Meanwhile, the reaction mechanism and stability of thiols SAMs on Ge (1 1 1) surface were investigated. Finally, highly stable passivated NDM SAMs on Ge surface could be formed through immersing oxide-free Ge in mixture solvent (water/ethanol, v/v = 1:1) at appropriately elevated temperature (∼80 °C) for 24 h. And the corresponding optimized passivated Ge surface was stable for more than 10 days even in water condition, which was much longer than the data reported and paved the way for the future practical applications of Ge.

  15. Electrodeposition at room temperature of amorphous silicon and germanium nanowires in ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Martineau, F; Namur, K; Mallet, J; Delavoie, F; Troyon, M; Molinari, M [Laboratoire de Microscopies et d' Etude de Nanostructures (LMEN EA3799), Universite de Reims Champagne Ardennes (URCA), Reims Cedex 2 (France); Endres, F, E-mail: michael.molinari@univ-reims.fr [Institute of Particle Technology, Chair of Interface Processes, Clausthal University of Technology, D-36678 Clausthal-Zellerfeld (Germany)

    2009-11-15

    The electrodeposition at room temperature of silicon and germanium nanowires from the air- and water-stable ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P{sub 1,4}) containing SiCl{sub 4} as Si source or GeCl{sub 4} as Ge source is investigated by cyclic voltammetry. By using nanoporous polycarbonate membranes as templates, it is possible to reproducibly grow pure silicon and germanium nanowires of different diameters. The nanowires are composed of pure amorphous silicon or germanium. The nanowires have homogeneous cylindrical shape with a roughness of a few nanometres on the wire surfaces. The nanowires' diameters and lengths well match with the initial membrane characteristics. Preliminary photoluminescence experiments exhibit strong emission in the near infrared for the amorphous silicon nanowires.

  16. γ production and neutron inelastic scattering cross sections for 76Ge

    Science.gov (United States)

    Rouki, C.; Domula, A. R.; Drohé, J. C.; Koning, A. J.; Plompen, A. J. M.; Zuber, K.

    2013-11-01

    The 2040.7-keV γ ray from the 69th excited state of 76Ge was investigated in the interest of Ge-based double-β-decay experiments like the Germanium Detector Array (GERDA) experiment. The predicted transition could interfere with valid 0νββ events at 2039.0 keV, creating false signals in large-volume 76Ge enriched detectors. The measurement was performed with the Gamma Array for Inelastic Neutron Scattering (GAINS) at the Geel Electron Linear Accelerator (GELINA) white neutron source, using the (n,n'γ) technique and focusing on the strongest γ rays originating from the level. Upper limits obtained for the production cross section of the 2040.7-keV γ ray showed no possible influence on GERDA data. Additional analysis of the data yielded high-resolution cross sections for the low-lying states of 76Ge and related γ rays, improving the accuracy and extending existing data for five transitions and five levels. The inelastic scattering cross section for 76Ge was determined for incident neutron energies up to 2.23 MeV, significantly increasing the energy range for which experimental data are available. Comparisons with model calculations using the talys code are presented indicating that accounting for the recently established asymmetric rotor structure should lead to an improved description of the data.

  17. Vanadocene reactions with mixed acylates of silicon, germanium and tin

    International Nuclear Information System (INIS)

    Latyaeva, V.N.; Lineva, A.N.; Zimina, S.V.; Gordetsov, A.S.; Dergunov, Yu.I.

    1981-01-01

    Vanadocene interaction with di-and tri-alkyl (aryl)-derivatives of silicon, tin and germanium is studied. Dibutyltin dibenzoate under mild conditions (20 deg C, toluene) oxidates vanadocene to [CpV(OCOC 6 H 5 ) 2 ] 2 , at that, the splitting off of one Cp group in the form of cyclopentadiene and formation of the products of tin-organic fragment disproportionation (tributyltin benzoate, dibutyltin, metallic tin) take place. Tributyltin benzoate oxidates vanadocene at the mole ratio 2:1 and during prolong heating (120 deg C) in the absence of the solvent, [CpV(OCOC 6 H 5 ) 2 ] 2 and hexabutyldistannate are the products of the reaction. Acetates R 3 SnOCOCH 3 react in the similar way. The reactivity of mono- and diacylates of germanium and silicon decreases in the series of derivatives Sn>Ge>Si [ru

  18. Mechanically-cooled germanium detector using two stirling refrigerators

    International Nuclear Information System (INIS)

    Katagiri, Masaki; Kobayashi, Yoshii; Takahashi, Koji

    1996-01-01

    In this paper, we present a developed mechanically-cooled germanium gamma-ray detector using Stirling refrigerators. Two Stirling refrigerators having cooling faculty of 1.5W at 80K were used to cool down a germanium detector element to 77K instead of a dewar containing liquid nitrogen. An 145cm 3 (56.0mmf x 59.1 mml) closed-end Ge(I) detector having relative detection efficiency of 29.4% was attached at the refrigerators. The size of the detector was 60cml x 15cmh x 15cmw. The lowest cooling temperature, 70K was obtained after 8 hours operation. The energy resolutions for 1.33MeV gamma-rays and for pulser signals were 2.43keV and 1.84keV at an amplifier shaping time of 2μsec, respectively

  19. Synthesis, Structure and Investigation of Germanium(IV and Copper(II Complexes with Malic Acid and 1,10ʹ-phenanthroline

    Directory of Open Access Journals (Sweden)

    Inna Seifullina

    2017-12-01

    Full Text Available Two crystalline compounds of germanium(IV with malic acid (HMal and 1,10ʹ-phenanthroline (phen - [Ge(HMal2(phen]•pheh•2H2O (I and [CuCl(phen2][Ge(OH(HMal2] (II were synthesized for the first time and characterized by elemental analysis, IR-spectroscopy and thermogravimetric analysis. There was elucidated from single-crystal X-ray diffraction that two different forms of Germanium are implemented: Ge4+ (I and hydrolyzed GeOH3+ (II to form distorted octahedron and pyramid respectively.

  20. Electronic and Mechanical Properties of GrapheneGermanium Interfaces Grown by Chemical Vapor Deposition

    Science.gov (United States)

    2015-10-27

    that graphene acts as a diffusion barrier to ambient contaminants, as similarly prepared bare Ge exposed to ambient conditions possesses a much...in-plane order underneath the graphene (Figure 1b,f). The stabilization of Ge terraces with half-step heights indicates that the graphene modifies the...Electronic and Mechanical Properties of Graphene −Germanium Interfaces Grown by Chemical Vapor Deposition Brian Kiraly,†,‡ Robert M. Jacobberger

  1. High-capacity nanostructured germanium-containing materials and lithium alloys thereof

    Energy Technology Data Exchange (ETDEWEB)

    Graetz, Jason A. (Upton, NY); Fultz, Brent T. (Pasadena, CA); Ahn, Channing (Pasadena, CA); Yazami, Rachid (Los Angeles, CA)

    2010-08-24

    Electrodes comprising an alkali metal, for example, lithium, alloyed with nanostructured materials of formula Si.sub.zGe.sub.(z-1), where 0Ge.sub.(z-1), where 0germanium exhibit a combination of improved capacities, cycle lives, and/or cycling rates compared with similar electrodes made from graphite. These electrodes are useful as anodes for secondary electrochemical cells, for example, batteries and electrochemical supercapacitors.

  2. Tunable band gap emission and surface passivation of germanium nanocrystals synthesized in the gas phase

    NARCIS (Netherlands)

    Wheeler, LM; Levij, L.M.; Kortshagen, U.R.

    2013-01-01

    The narrow bulk band gap and large exciton Bohr radius of germanium (Ge) make it an attractive material for optoelectronics utilizing band-gap-tunable photoluminescence (PL). However, realization of PL due to quantum confinement remains scarcely reported. Instead, PL is often observed from surface

  3. Hall mobility of free charge carriers in highly compensated p-Germanium

    International Nuclear Information System (INIS)

    Gavrilyuk, V.Yi.; Kirnas, Yi.G.; Balakyin, V.D.

    2000-01-01

    Hall mobility of free charge carriers in initial detectors Ge (Ga) is studied. It is established that an increase in the compensation factor results in the enlargement of Hall mobility in germanium highly compensated by introduction of Li ions during their drift in an electrical field

  4. Buried Porous Silicon-Germanium Layers in Monocrystalline Silicon Lattices

    Science.gov (United States)

    Fathauer, Robert W. (Inventor); George, Thomas (Inventor); Jones, Eric W. (Inventor)

    1998-01-01

    Monocrystalline semiconductor lattices with a buried porous semiconductor layer having different chemical composition is discussed and monocrystalline semiconductor superlattices with a buried porous semiconductor layers having different chemical composition than that of its monocrystalline semiconductor superlattice are discussed. Lattices of alternating layers of monocrystalline silicon and porous silicon-germanium have been produced. These single crystal lattices have been fabricated by epitaxial growth of Si and Si-Ge layers followed by patterning into mesa structures. The mesa structures are strain etched resulting in porosification of the Si-Ge layers with a minor amount of porosification of the monocrystalline Si layers. Thicker Si-Ge layers produced in a similar manner emitted visible light at room temperature.

  5. Neutron-capture cross-section measurements of 74Ge and 76Ge in the energy region 0.4-14.8 MeV for neutrinoless double β decay applications

    Science.gov (United States)

    Bhike, Megha; Tornow, Werner

    2013-10-01

    Fast neutron capture cross sections for the reactions 74Ge(n, γ)75Ge and 76Ge(n, γ)77Ge have been measured in the neutron energy region 0.4-14.8 MeV with the activation method. The results are important to identify backgrounds in the neutrinoless double- β decay experiments GERDA and MAJORANA, which use germanium as both source and detector. Isotopically enriched targets which consisted of 86% of 76Ge and 14% of 74Ge were irradiated with mono-energetic neutrons produced via 3H(p,n)3He, 2H(d,n)3He and 3H(d,n)4He reactions. The cross sections were determined relative to 197Au(n, γ)198Au, 115In(n,n')115mIn and 197Au(n,2n)196Au standard cross sections. The activities of the products were measured using high-resolution γ-ray spctroscopy. The present results are compared with the evaluated data from ENDF/B-VII.1 and TALYS.

  6. Status report on the International Germanium Experiment

    International Nuclear Information System (INIS)

    Brodzinski, R.L.; Avignone, F.T.; Collar, J.I.; Courant, H.; Garcia, E.; Guerard, C.K.; Hensley, W.K.; Kirpichnikov, I.V.; Miley, H.S.; Morales, A.; Morales, J.; Nunez-Lagos, R.; Osetrov, S.B.; Pogosov, V.S.; Pomansky, A.A.; Puimedon, J.; Reeves, J.H.; Ruddick, K.; Saenz, C.; Salinas, A.; Sarsa, M.L.; Smolnikov, A.A.; Starostin, A.S.; Tamanyan, A.G.; Vasiliev, S.I.; Villar, J.A.

    1993-01-01

    Phase II detector fabrication for the International Germanium Experiment is in progress. Sources of background observed during Phase I are discussed. Cosmogenic 7 Be is measured in germanium. Radium contamination, presumably in electroformed copper, is reported. (orig.)

  7. Status report on the International Germanium Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Brodzinski, R L; Avignone, F.T.; Collar, J I; Courant, H; Garcia, E; Guerard, C K; Hensley, W K; Kirpichnikov, I V; Miley, H S; Morales, A; Morales, J; Nunez-Lagos, R; Osetrov, S B; Pogosov, V S; Pomansky, A A; Puimedon, J; Reeves, J H; Ruddick, K; Saenz, C; Salinas, A; Sarsa, M L; Smolnikov, A A; Starostin, A S; Tamanyan, A G; Vasiliev, S I; Villar, J A [Pacific Northwest Lab., Richland, WA (United States) Univ. of South Carolina, Columbia, SC (United States) Univ. of Minnesota, Minneapolis, MN (United States) Univ. of Zaragoza (Spain) Inst. for Theoretical and Experimental Physics, Moscow (Russian Federation) Inst. for Nuclear Research, Baksan Neutrino Observatory (Russian Federation) Yerevan Physical Inst., Yerevan (Armenia)

    1993-04-01

    Phase II detector fabrication for the International Germanium Experiment is in progress. Sources of background observed during Phase I are discussed. Cosmogenic [sup 7]Be is measured in germanium. Radium contamination, presumably in electroformed copper, is reported. (orig.)

  8. Boron doping compensation of hydrogenated amorphous and polymorphous germanium thin films for infrared detection applications

    International Nuclear Information System (INIS)

    Moreno, M.; Delgadillo, N.; Torres, A.; Ambrosio, R.; Rosales, P.; Kosarev, A.; Reyes-Betanzo, C.; Hidalga-Wade, J. de la; Zuniga, C.; Calleja, W.

    2013-01-01

    In this work we have studied boron doping of hydrogenated amorphous germanium a-Ge:H and polymorphous germanium (pm-Ge:H) in low regimes, in order to compensate the material from n-type (due to oxygen contamination that commonly occurs during plasma deposition) to intrinsic, and in this manner improve the properties that are important for infrared (IR) detection, as activation energy (E a ) and temperature coefficient of resistance (TCR). Electrical, structural and optical characterization was performed on the films produced. Measurements of the temperature dependence of conductivity, room temperature conductivity (σ RT ), E a and current–voltage characteristics under IR radiation were performed in the compensated a-Ge:H and pm-Ge:H films. Our results demonstrate that, effectively, the values of E a , TCR and IR detection are improved on the a-Ge:H/pm-Ge:H films, using boron doping in low regimes, which results of interest for infrared detectors. - Highlights: • We reported boron doping compensation of amorphous and polymorphous germanium. • The films were deposited by plasma enhanced chemical vapor deposition. • The aim is to use the films as thermo-sensing elements in un-cooled microbolometers. • Those films have advantages over boron doped a-Si:H used in commercial detectors

  9. Boron doping compensation of hydrogenated amorphous and polymorphous germanium thin films for infrared detection applications

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, M., E-mail: mmoreno@inaoep.mx [National Institute of Astrophysics, Optics and Electronics, INAOE, P.O. Box 51 and 216, Puebla, Z. P. 72840 Puebla (Mexico); Delgadillo, N. [Universidad Autónoma de Tlaxcala, Av. Universidad No. 1, Z. P. 90006 Tlaxcala (Mexico); Torres, A. [National Institute of Astrophysics, Optics and Electronics, INAOE, P.O. Box 51 and 216, Puebla, Z. P. 72840 Puebla (Mexico); Ambrosio, R. [Technology and Engineering Institute, Ciudad Juarez University UACJ, Av. Del Charro 450N, Z. P. 32310 Chihuahua (Mexico); Rosales, P.; Kosarev, A.; Reyes-Betanzo, C.; Hidalga-Wade, J. de la; Zuniga, C.; Calleja, W. [National Institute of Astrophysics, Optics and Electronics, INAOE, P.O. Box 51 and 216, Puebla, Z. P. 72840 Puebla (Mexico)

    2013-12-02

    In this work we have studied boron doping of hydrogenated amorphous germanium a-Ge:H and polymorphous germanium (pm-Ge:H) in low regimes, in order to compensate the material from n-type (due to oxygen contamination that commonly occurs during plasma deposition) to intrinsic, and in this manner improve the properties that are important for infrared (IR) detection, as activation energy (E{sub a}) and temperature coefficient of resistance (TCR). Electrical, structural and optical characterization was performed on the films produced. Measurements of the temperature dependence of conductivity, room temperature conductivity (σ{sub RT}), E{sub a} and current–voltage characteristics under IR radiation were performed in the compensated a-Ge:H and pm-Ge:H films. Our results demonstrate that, effectively, the values of E{sub a}, TCR and IR detection are improved on the a-Ge:H/pm-Ge:H films, using boron doping in low regimes, which results of interest for infrared detectors. - Highlights: • We reported boron doping compensation of amorphous and polymorphous germanium. • The films were deposited by plasma enhanced chemical vapor deposition. • The aim is to use the films as thermo-sensing elements in un-cooled microbolometers. • Those films have advantages over boron doped a-Si:H used in commercial detectors.

  10. Ion-beam induced structure modifications in amorphous germanium; Ionenstrahlinduzierte Strukturmodifikationen in amorphem Germanium

    Energy Technology Data Exchange (ETDEWEB)

    Steinbach, Tobias

    2012-05-03

    Object of the present thesis was the systematic study of ion-beam induced structure modifications in amorphous germanium (a-Ge) layers due to low- (LEI) and high-energetic (SHI) ion irradiation. The LEI irradiation of crystalline Ge (c-Ge) effects because the dominating nuclear scattering of the ions on the solid-state atoms the formation of a homogeneous a-Ge Layer. Directly on the surface for fluences of two orders of magnitude above the amorphization fluence the formation of stable cavities independently on the irradiation conditions was observed. For the first time for the ion-beam induced cavity formation respectively for the steady expansion of the porous layer forming with growing fluence a linear dependence on the energy {epsilon}{sub n} deposed in nuclear processes was detected. Furthermore the formation of buried cavities was observed, which shows a dependence on the type of ions. While in the c-Ge samples in the range of the high electronic energy deposition no radiation defects, cavities, or plastic deformations were observed, the high electronic energy transfer in the 3.1 {mu}m thick pre-amorphized a-Ge surface layers leads to the formation of randomly distributed cavities. Basing on the linear connection between cavity-induced vertical volume expansion and the fluence determined for different energy transfers for the first time a material-specific threshold value of {epsilon}{sub e}{sup HRF}=(10.5{+-}1.0) kev nm{sup -1} was determined, above which the ion-beam induced cavity formation in a-Ge sets on. The anisotropic plastic deformation of th a-Ge layer superposed at inclined SHI irradiation on the cavity formation was very well described by an equation derived from the viscoelastic Maxwell model, but modified under regardment of the experimental results. The positive deformation yields determined thereby exhibit above a threshold value for the ion-beam induced plastic deformation {epsilon}{sub e}{sup S{sub a}}=(12{+-}2) keV nm{sup -1} for the first

  11. Influence of grain size on lithium storage performance of germanium oxide films

    International Nuclear Information System (INIS)

    Feng, J.K.; Lai, M.O.; Lu, L.

    2012-01-01

    Highlights: ► We deposited GeO 2 thin films at different temperatures to form different grain sizes. ► Li storage of GeO 2 as anode was studied, which shows that the GeO 2 with grain size of about 10 nm reveals high capacity retention. ► Nanograined GeO 2 also shows better rate capability and cyclability. - Abstract: Germanium oxide (GeO 2 ) films with two different grain sizes of 10 nm (GeO 2 (10 nm)) and 100 nm (GeO 2 (100 nm)) were grown via reactive radio frequency sputtering at different temperatures. Electrochemical measurements of the GeO 2 (10 nm) thin film used as an anode in Li ion rechargeable batteries show superior capacity retention and rate capability compared to those of GeO 2 (100 nm). The GeO 2 (10 nm) thin film possesses an initial capacity of 930 mAh g −1 with 89% capacity retention after 100 cycles, compared with 455 mAh g −1 with 53% of GeO 2 (100 nm) and 225 mAh g −1 , 30% (10 cycles) of common macro-size GeO 2 . Microstructural studies reveal that the GeO 2 (10 nm) thin film can better accommodate volume changes during Li–Ge alloying and de-alloying processes.

  12. Lithium germanium detectors reactivation

    International Nuclear Information System (INIS)

    Nicolai, J.A.; Marti, G.V.; Riso, J.M.; Gimenez, C.R.

    1981-01-01

    A convenient method to regenerate the characteristics of damaged Ge(li) detectors, that has been applied in the authors' laboratory, is described. The procedure consists in warming-up the crystal in its cryostat to temperatures between 10 deg C and 30 deg C above room temperature, in order to clean its surface. Subsequent cooling down to liquid nitrogen temperature, followed by one or more clean-up drifting processes, are applied to the crystals. This paper summarizes the results obtained with several detectors; this method was applied successfully to 15 detectors more. (author) [es

  13. Background-free search for neutrinoless double-β decay of 76Ge with GERDA

    Science.gov (United States)

    Agostini, M.; Allardt, M.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Baudis, L.; Bauer, C.; Bellotti, E.; Belogurov, S.; Belyaev, S. T.; Benato, G.; Bettini, A.; Bezrukov, L.; Bode, T.; Borowicz, D.; Brudanin, V.; Brugnera, R.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; D'Andrea, V.; Demidova, E. V.; di Marco, N.; di Vacri, A.; Domula, A.; Doroshkevich, E.; Egorov, V.; Falkenstein, R.; Fedorova, O.; Freund, K.; Frodyma, N.; Gangapshev, A.; Garfagnini, A.; Gooch, C.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Hakenmüller, J.; Hegai, A.; Heisel, M.; Hemmer, S.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Janicskó Csáthy, J.; Jochum, J.; Junker, M.; Kazalov, V.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Kish, A.; Klimenko, A.; Kneißl, R.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lebedev, V. I.; Lehnert, B.; Liao, H. Y.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Majorovits, B.; Maneschg, W.; Medinaceli, E.; Miloradovic, M.; Mingazheva, R.; Misiaszek, M.; Moseev, P.; Nemchenok, I.; Palioselitis, D.; Panas, K.; Pandola, L.; Pelczar, K.; Pullia, A.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salamida, F.; Salathe, M.; Schmitt, C.; Schneider, B.; Schönert, S.; Schreiner, J.; Schulz, O.; Schütz, A.-K.; Schwingenheuer, B.; Selivanenko, O.; Shevchik, E.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Vanhoefer, L.; Vasenko, A. A.; Veresnikova, A.; von Sturm, K.; Wagner, V.; Walter, M.; Wegmann, A.; Wester, T.; Wiesinger, C.; Wojcik, M.; Yanovich, E.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zuber, K.; Zuzel, G.; GERDA Collaboration

    2017-04-01

    Many extensions of the Standard Model of particle physics explain the dominance of matter over antimatter in our Universe by neutrinos being their own antiparticles. This would imply the existence of neutrinoless double-β decay, which is an extremely rare lepton-number-violating radioactive decay process whose detection requires the utmost background suppression. Among the programmes that aim to detect this decay, the GERDA Collaboration is searching for neutrinoless double-β decay of 76Ge by operating bare detectors, made of germanium with an enriched 76Ge fraction, in liquid argon. After having completed Phase I of data taking, we have recently launched Phase II. Here we report that in GERDA Phase II we have achieved a background level of approximately 10-3 counts keV-1 kg-1 yr-1. This implies that the experiment is background-free, even when increasing the exposure up to design level. This is achieved by use of an active veto system, superior germanium detector energy resolution and improved background recognition of our new detectors. No signal of neutrinoless double-β decay was found when Phase I and Phase II data were combined, and we deduce a lower-limit half-life of 5.3 × 1025 years at the 90 per cent confidence level. Our half-life sensitivity of 4.0 × 1025 years is competitive with the best experiments that use a substantially larger isotope mass. The potential of an essentially background-free search for neutrinoless double-β decay will facilitate a larger germanium experiment with sensitivity levels that will bring us closer to clarifying whether neutrinos are their own antiparticles.

  14. Structure and Stability of GeAun, n = 1-10 clusters: A Density Functional Study

    International Nuclear Information System (INIS)

    Priyanka,; Dharamvir, Keya; Sharma, Hitesh

    2011-01-01

    The structures of Germanium doped gold clusters GeAu n (n = 1-10) have been investigated using ab initio calculations based on density functional theory (DFT). We have obtained ground state geometries of GeAu n clusters and have it compared with Silicon doped gold clusters and pure gold clusters. The ground state geometries of the GeAu n clusters show patterns similar to silicon doped gold clusters except for n = 5, 6 and 9. The introduction of germanium atom increases the binding energy of gold clusters. The binding energy per atom of germanium doped cluster is smaller than the corresponding silicon doped gold cluster. The HUMO-LOMO gap for Au n Ge clusters have been found to vary between 0.46 eV-2.09 eV. The mullikan charge analysis indicates that charge of order of 0.1e always transfers from germanium atom to gold atom.

  15. Cryocooler and Thermal Systems for Improved GeD Gamma-ray Imaging and Spectroscopy

    Data.gov (United States)

    National Aeronautics and Space Administration — Place Germanium detectors (GeDs) in a few-MeV γ-ray Compton instrument on a satellite will enable unprecedented insight into nuclear astrophysics, key multimessenger...

  16. Effect of pressure on arsenic diffusion in germanium

    International Nuclear Information System (INIS)

    Mitha, S.; Theiss, S.D.; Aziz, M.J.; Schiferl, D.; Poker, D.B.

    1994-01-01

    We report preliminary results of a study of the activation volume for diffusion of arsenic in germanium. High-temperature high-pressure anneals were performed in a liquid argon pressure medium in a diamond anvil cell capable of reaching 5 GPa and 750 C,l which is externally heated for uniform and repeatable temperature profiles. Broadening of an ion-implanted arsenic profile was measured by Secondary Ion Mass Spectrometry. Hydrostatic pressure retards the diffusivity at 575 C, characterized by an activation volume that is +15% of the atomic volume of Ge. Implications for diffusion mechanisms are discussed

  17. Comparative Study of Phase Transformation in Single-Crystal Germanium during Single and Cyclic Nanoindentation

    Directory of Open Access Journals (Sweden)

    Koji Kosai

    2017-11-01

    Full Text Available Single-crystal germanium is a semiconductor material which shows complicated phase transformation under high pressure. In this study, new insight into the phase transformation of diamond-cubic germanium (dc-Ge was attempted by controlled cyclic nanoindentation combined with Raman spectroscopic analysis. Phase transformation from dc-Ge to rhombohedral phase (r8-Ge was experimentally confirmed for both single and cyclic nanoindentation under high loading/unloading rates. However, compared to single indentation, double cyclic indentation with a low holding load between the cycles caused more frequent phase transformation events. Double cyclic indentation caused more stress in Ge than single indentation and increased the possibility of phase transformation. With increase in the holding load, the number of phase transformation events decreased and finally became less than that under single indentation. This phenomenon was possibly caused by defect nucleation and shear accumulation during the holding process, which were promoted by a high holding load. The defect nucleation suppressed the phase transformation from dc-Ge to r8-Ge, and shear accumulation led to another phase transformation pathway, respectively. A high holding load promoted these two phenomena, and thus decreased the possibility of phase transformation from dc-Ge to r8-Ge.

  18. Effect of Ge atoms on crystal structure and optoelectronic properties of hydrogenated Si-Ge films

    Science.gov (United States)

    Li, Tianwei; Zhang, Jianjun; Ma, Ying; Yu, Yunwu; Zhao, Ying

    2017-07-01

    Optoelectronic and structural properties of hydrogenated microcrystalline silicon-germanium (μc-Si1-xGex:H) alloys prepared by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) were investigated. When the Ge atoms were predominantly incorporated in amorphous matrix, the dark and photo-conductivity decreased due to the reduced crystalline volume fraction of the Si atoms (XSi-Si) and the increased Ge dangling bond density. The photosensitivity decreased monotonously with Ge incorporation under higher hydrogen dilution condition, which was attributed to the increase in both crystallization of Ge and the defect density.

  19. Reduced graphene oxide-germanium quantum dot nanocomposite: electronic, optical and magnetic properties

    Science.gov (United States)

    Amollo, Tabitha A.; Mola, Genene T.; Nyamori, Vincent O.

    2017-12-01

    Graphene provides numerous possibilities for structural modification and functionalization of its carbon backbone. Localized magnetic moments can, as well, be induced in graphene by the formation of structural defects which include vacancies, edges, and adatoms. In this work, graphene was functionalized using germanium atoms, we report the effect of the Ge ad atoms on the structural, electrical, optical and magnetic properties of graphene. Reduced graphene oxide (rGO)-germanium quantum dot nanocomposites of high crystalline quality were synthesized by the microwave-assisted solvothermal reaction. Highly crystalline spherical shaped germanium quantum dots, of diameter ranging between 1.6-9.0 nm, are anchored on the basal planes of rGO. The nanocomposites exhibit high electrical conductivity with a sheet resistance of up to 16 Ω sq-1. The electrical conductivity is observed to increase with the increase in Ge content in the nanocomposites. High defect-induced magnetization is attained in the composites via germanium adatoms. The evolution of the magnetic moments in the nanocomposites and the coercivity showed marked dependence on the Ge quantum dots size and concentration. Quantum confinement effects is evidenced in the UV-vis absorbance spectra and photoluminescence emission spectra of the nanocomposites which show marked size-dependence. The composites manifest strong absorption in the UV region, strong luminescence in the near UV region, and a moderate luminescence in the visible region.

  20. Probing ge distribution in zeolite frameworks by post-synthesis introduction of fluoride in as-made materials

    KAUST Repository

    Liu, Xiaolong

    2012-08-14

    A new method has been developed to introduce fluoride in the structure of as-made germanium-containing zeolites prepared under pure alkaline media. Incorporation of fluoride species occurs without modification of the framework composition (Si/Ge ratio) and of the crystallinity, as evidenced by X-ray diffraction and electron microscopy. After incorporation, 19F solid-state NMR has been used to probe the location and distribution of Ge atoms in the framework. In the case of ITQ-13 and ITQ-17, which can be prepared from both hydroxide and fluoride routes, incorporated F anions are located in the same structural units as those occupied when zeolites are prepared in the presence of fluoride. In the case of ITQ-22 and ITQ-24, fluoride goes mainly in D4R units, which appear to be in the most energetically favorable positions for these zeolites. All experiments clearly show that zeolites prepared in the absence of fluoride in the synthesis medium are enriched in germanium, compared to the same materials obtained from F-containing gels. Moreover, Ge plays a strong structure-directing role by replacing Si atoms preferentially in D4R, leading to zeolites with mainly [4Si, 4Ge] units in the framework. In the particular case of ITQ-22, a new line observed around -2 ppm in 19F NMR spectra has been tentatively assigned to [3Si, 5Ge] D4R units, which corroborates the structural data obtained via X-ray diffraction. © 2012 American Chemical Society.

  1. The distribution of gallium, germanium and indium in conventional and non-conventional resources. Implications for global availability

    Energy Technology Data Exchange (ETDEWEB)

    Frenzel, Max

    2016-10-25

    , a large collection of analytical data was compiled from the scientific literature. A general estimation method for by-product supply potentials was then developed and applied to all three elements. Due to the nature of the available data and associated difficulties, the compilation of these estimates constitutes the major part of this work. Comparison of the results shows that there are distinct differences between the supply potentials of gallium, germanium and indium: While the current extraction rate of gallium and germanium is about one order of magnitude below their supply potential, the best estimate for the supply potential of indium is very close to its current primary production. This, as well as the exceedingly fast growth rate of indium production over the past 20 years, might indicate imminent supply problems. In contrast, similar problems are not expected for gallium and germanium. From this understanding of both current supply potentials and historic developments, a new indicator for the physical supply risk of by-product elements is developed. It adequately captures the key features of the physical supply situation and should therefore be useful in future criticality assessments. In addition to these economic considerations, the other aim of this thesis was to examine existing geochemical data in more detail, and thus explain the enrichment of gallium, germanium and indium to commercially interesting levels in certain geological settings. The general results suggest that geochemistry and supply situation are, unsurprisingly, not independent. In particular, the greater scarcity of indium in the Earth's crust apparently leads to a limitation of the environments in which it is found enriched to extractable concentrations. This in turn leads to a more limited supply potential compared to current rates of production, and consequently, tight supply and a higher risk of supply disruptions, when compared to gallium and germanium. Particular attention was

  2. GERDA results and the future perspectives for the neutrinoless double beta decay search using 76Ge

    Science.gov (United States)

    Agostini, M.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Baudis, L.; Bauer, C.; Bellotti, E.; Belogurov, S.; Bettini, A.; Bezrukov, L.; Biernat, J.; Bode, T.; Borowicz, D.; Brudanin, V.; Brugnera, R.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; Comellato, T.; D’Andrea, V.; Demidova, E. V.; di Marco, N.; Domula, A.; Doroshkevich, E.; Egorov, V.; Gangapshev, A.; Garfagnini, A.; Giordano, M.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Hakenmüller, J.; Heisel, M.; Hemmer, S.; Hiller, R.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Janicskó Csáthy, J.; Jochum, J.; Junker, M.; Kazalov, V.; Kermaidic, Y.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Klimenko, A.; Kneißl, R.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Majorovits, B.; Maneschg, W.; Miloradovic, M.; Mingazheva, R.; Misiaszek, M.; Moseev, P.; Nemchenok, I.; Panas, K.; Pandola, L.; Pelczar, K.; Pertoldi, L.; Pullia, A.; Ransom, C.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salamida, F.; Schneider, B.; Schönert, S.; Schreiner, J.; Schütz, A.-K.; Schulz, O.; Schwingenheuer, B.; Selivanenko, O.; Shevchik, E.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Vanhoefer, L.; Vasenko, A. A.; Veresnikova, A.; von Sturm, K.; Wagner, V.; Wegmann, A.; Wester, T.; Wiesinger, C.; Wojcik, M.; Yanovich, E.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zschocke, A.; Zsigmond, A. J.; Zuber, K.; Zuzel, G.

    2018-03-01

    The GERmanium Detector Array (GERDA) is a low background experiment at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN designed to search for the rare neutrinoless double beta decay (0νββ) of 76Ge. In the first phase (Phase I) of the experiment, high purity germanium diodes were operated in a “bare” mode and immersed in liquid argon. The overall background level of 10‑2cts/(keV ṡkg ṡyr) was a factor of ten better than those of its predecessors. No signal was found and a lower limit was set on the half-life for the 0νββ decay of 76Ge T1/20ν > 2.1 × 1025 yr (90% CL), while the corresponding median sensitivity was 2.4 × 1025 yr (90% CL). A second phase (Phase II) started at the end of 2015 after a major upgrade. Thanks to the increased detector mass and performance of the enriched germanium diodes and due to the introduction of liquid argon instrumentation techniques, it was possible to reduce the background down to 10‑3cts/(keV ṡkg ṡyr). After analyzing 23.2 kgṡyr of these new data no signal was seen. Combining these with the data from Phase I a stronger half-life limit of the 76Ge 0νββ decay was obtained: T1/20ν > 8.0 × 1025 yr (90% CL), reaching a sensitivity of 5.8 × 1025 yr (90% CL). Phase II will continue for the collection of an exposure of 100 kg ṡyr. If no signal is found by then the GERDA sensitivity will have reached 1.4 × 1026 yr for setting a 90% CL. limit. After the end of GERDA Phase II, the flagship experiment for the search of 0νββ decay of 76Ge will be LEGEND. LEGEND experiment is foreseen to deploy up to 1-ton of 76Ge. After ten years of data taking, it will reach a sensitivity beyond 1028 yr, and hence fully cover the inverted hierarchy region.

  3. Electrical Manipulation of Donor Spin Qubits in Silicon and Germanium

    Science.gov (United States)

    Sigillito, Anthony James

    Many proposals for quantum information devices rely on electronic or nuclear spins in semiconductors because of their long coherence times and compatibility with industrial fabrication processes. One of the most notable qubits is the electron spin bound to phosphorus donors in silicon, which offers coherence times exceeding seconds at low temperatures. These donors are naturally isolated from their environments to the extent that silicon has been coined a "semiconductor vacuum". While this makes for ultra-coherent qubits, it is difficult to couple two remote donors so quantum information proposals rely on high density arrays of qubits. Here, single qubit addressability becomes an issue. Ideally one would address individual qubits using electric fields which can be easily confined. Typically these schemes rely on tuning a donor spin qubit onto and off of resonance with a magnetic driving field. In this thesis, we measure the electrical tunability of phosphorus donors in silicon and use the extracted parameters to estimate the effects of electric-field noise on qubit coherence times. Our measurements show that donor ionization may set in before electron spins can be sufficiently tuned. We therefore explore two alternative options for qubit addressability. First, we demonstrate that nuclear spin qubits can be directly driven using electric fields instead of magnetic fields and show that this approach offers several advantages over magnetically driven spin resonance. In particular, spin transitions can occur at half the spin resonance frequency and double quantum transitions (magnetic-dipole forbidden) can occur. In a second approach to realizing tunable qubits in semiconductors, we explore the option of replacing silicon with germanium. We first measure the coherence and relaxation times for shallow donor spin qubits in natural and isotopically enriched germanium. We find that in isotopically enriched material, coherence times can exceed 1 ms and are limited by a

  4. Improved Limit on Neutrinoless Double-β Decay of Ge 76 from GERDA Phase II

    Science.gov (United States)

    Agostini, M.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Baudis, L.; Bauer, C.; Bellotti, E.; Belogurov, S.; Bettini, A.; Bezrukov, L.; Biernat, J.; Bode, T.; Borowicz, D.; Brudanin, V.; Brugnera, R.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; Comellato, T.; D'Andrea, V.; Demidova, E. V.; di Marco, N.; Domula, A.; Doroshkevich, E.; Egorov, V.; Falkenstein, R.; Gangapshev, A.; Garfagnini, A.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Hakenmüller, J.; Hegai, A.; Heisel, M.; Hemmer, S.; Hiller, R.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Janicskó Csáthy, J.; Jochum, J.; Junker, M.; Kazalov, V.; Kermaidic, Y.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Kish, A.; Klimenko, A.; Kneißl, R.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Majorovits, B.; Maneschg, W.; Miloradovic, M.; Mingazheva, R.; Misiaszek, M.; Moseev, P.; Nemchenok, I.; Panas, K.; Pandola, L.; Pelczar, K.; Pertoldi, L.; Pullia, A.; Ransom, C.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salamida, F.; Schmitt, C.; Schneider, B.; Schönert, S.; Schütz, A.-K.; Schulz, O.; Schwingenheuer, B.; Selivanenko, O.; Shevchik, E.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Vanhoefer, L.; Vasenko, A. A.; Veresnikova, A.; von Sturm, K.; Wagner, V.; Wegmann, A.; Wester, T.; Wiesinger, C.; Wojcik, M.; Yanovich, E.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zschocke, A.; Zsigmond, A. J.; Zuber, K.; Zuzel, G.; Gerda Collaboration

    2018-03-01

    The GERDA experiment searches for the lepton-number-violating neutrinoless double-β decay of Ge 76 (Ge 76 →Se 76 +2 e- ) operating bare Ge diodes with an enriched Ge 76 fraction in liquid argon. The exposure for broad-energy germanium type (BEGe) detectors is increased threefold with respect to our previous data release. The BEGe detectors feature an excellent background suppression from the analysis of the time profile of the detector signals. In the analysis window a background level of 1. 0-0.4+0.6×10-3 counts /(keV kg yr ) has been achieved; if normalized to the energy resolution this is the lowest ever achieved in any 0 νβ β experiment. No signal is observed and a new 90% C.L. lower limit for the half-life of 8.0 ×1025 yr is placed when combining with our previous data. The expected median sensitivity assuming no signal is 5.8 ×1025 yr .

  5. The Majorana Demonstrator: Progress towards showing the feasibility of a tonne-scale 76Ge neutrinoless double-beta decay experiment

    Science.gov (United States)

    Finnerty, P.; Aguayo, E.; Amman, M.; Avignone, F. T., Iii; Barabash, A. S.; Barton, P. J.; Beene, J. R.; Bertrand, F. E.; Boswell, M.; Brudanin, V.; Busch, M.; Chan, Y.-D.; Christofferson, C. D.; Collar, J. I.; Combs, D. C.; Cooper, R. J.; Detwiler, J. A.; Doe, P. J.; Efremenko, Yu; Egorov, V.; Ejiri, H.; Elliott, S. R.; Esterline, J.; Fast, J. E.; Fields, N.; Fraenkle, F. M.; Galindo-Uribarri, A.; Gehman, V. M.; Giovanetti, G. K.; Green, M. P.; Guiseppe, V. E.; Gusey, K.; Hallin, A. L.; Hazama, R.; Henning, R.; Hoppe, E. W.; Horton, M.; Howard, S.; Howe, M. A.; Johnson, R. A.; Keeter, K. J.; Kidd, M. F.; Knecht, A.; Kochetov, O.; Konovalov, S. I.; Kouzes, R. T.; LaFerriere, B. D.; Leon, J.; Leviner, L. E.; Loach, J. C.; Luke, P. N.; MacMullin, S.; Marino, M. G.; Martin, R. D.; Merriman, J. H.; Miller, M. L.; Mizouni, L.; Nomachi, M.; Orrell, J. L.; Overman, N. R.; Perumpilly, G.; Phillips, D. G., Ii; Poon, A. W. P.; Radford, D. C.; Rielage, K.; Robertson, R. G. H.; Ronquest, M. C.; Schubert, A. G.; Shima, T.; Shirchenko, M.; Snavely, K. J.; Steele, D.; Strain, J.; Timkin, V.; Tornow, W.; Varner, R. L.; Vetter, K.; Vorren, K.; Wilkerson, J. F.; Yakushev, E.; Yaver, H.; Young, A. R.; Yu, C.-H.; Yumatov, V.; Majorana Collaboration

    2014-03-01

    The Majorana Demonstrator will search for the neutrinoless double-beta decay (0vββ) of the 76Ge isotope with a mixed array of enriched and natural germanium detectors. The observation of this rare decay would indicate the neutrino is its own anti-particle, demonstrate that lepton number is not conserved, and provide information on the absolute mass-scale of the neutrino. The Demonstrator is being assembled at the 4850 foot level of the Sanford Underground Research Facility in Lead, South Dakota. The array will be contained in a low-background environment and surrounded by passive and active shielding. The goals for the Demonstrator are: demonstrating a background rate less than 3 t-1 y-1 in the 4 keV region of interest (ROI) surrounding the 2039 keV 76Ge endpoint energy; establishing the technology required to build a tonne-scale germanium based double-beta decay experiment; testing the recent claim of observation of 0vββ [1]; and performing a direct search for light WIMPs (3-10 GeV/c2).

  6. Humidity-dependent stability of amorphous germanium nitrides fabricated by plasma nitridation

    International Nuclear Information System (INIS)

    Kutsuki, Katsuhiro; Okamoto, Gaku; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji

    2007-01-01

    We have investigated the stability of amorphous germanium nitride (Ge 3 N 4 ) layers formed by plasma nitridation of Ge(100) surfaces using x-ray photoelectron spectroscopy and atomic force microscopy. We have found that humidity in the air accelerates the degradation of Ge 3 N 4 layers and that under 80% humidity condition, most of the Ge-N bonds convert to Ge-O bonds, producing a uniform GeO 2 layer, within 12 h even at room temperature. After this conversion of nitrides to oxides, the surface roughness drastically increased by forming GeO 2 islands on the surfaces. These findings indicate that although Ge 3 N 4 layers have superior thermal stability compared to the GeO 2 layers, Ge 3 N 4 reacts readily with hydroxyl groups and it is therefore essential to take the best care of the moisture in the fabrication of Ge-based devices with Ge 3 N 4 insulator or passivation layers

  7. Experimental investigation on oxidation kinetics of germanium by ozone

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaolei, E-mail: wangxiaolei@ime.ac.cn [Key Laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China); Zhao, Zhiqian; Xiang, Jinjuan [Key Laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China); Wang, Wenwu, E-mail: wangwenwu@ime.ac.cn [Key Laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China); Zhang, Jing, E-mail: zhangj@ncut.edu.cn [Key Laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China); Microelectronics Department, North China University of Technology, Beijing 100041 (China); Zhao, Chao; Ye, Tianchun [Key Laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China)

    2016-12-30

    Highlights: • Kinetics mechanism of Ge surface oxidation by ozone at low temperature is experimentally investigated. • The growth process contains initially linear growth region and following parabolic growth region. • The GeO{sub x} thickness vs. oxidation time plot obeys the well-known Deal-Grove or linear parabolic model. • The linear growth region includes the oxidation of two topmost Ge layers, and the oxidation of third layer and following layers of Ge is diffusion limited. • The activation energies for linear and parabolic regions are 0.04 and 0.55 eV, respectively. - Abstract: Oxidation kinetics of germanium surface by ozone at low temperature (≤400 °C) is experimentally investigated. The growth process contains two regions: initial linear growth region and following parabolic growth region. The GeO{sub x} thickness vs. oxidation time plot obeys the well-known Deal-Grove or linear parabolic model. The linear growth region contains reaction of oxygen atoms with surface bond and back bonds of outmost Ge layer. And the activation energy is experimentally estimated to be 0.06 eV. Such small activation energy indicates that the linear growth region is nearly barrier-less. The parabolic growth region starts when the oxygen atoms diffuse into back bonds of second outmost Ge layers. And the activation energy for this process is found to be 0.54 eV. Furthermore, in the ozone oxidation it is not O{sub 3} molecules but O radicals that go through the GeO{sub x} film.

  8. Maximizing Tensile Strain in Germanium Nanomembranes for Enhanced Optoelectronic Properties

    Science.gov (United States)

    Sanchez Perez, Jose Roberto

    Silicon, germanium, and their alloys, which provide the leading materials platform of microelectronics, are extremely inefficient light emitters because of their indirect fundamental energy band gap. This basic materials property has so far hindered the development of group-IV photonic-active devices, including light emitters and diode lasers, thereby significantly limiting our ability to integrate electronic and photonic functionalities at the chip level. Theoretical studies have predicted that tensile strain in Ge lowers the direct energy band gap relative to the indirect one, and that, with sufficient strain, Ge becomes direct-band gap, thus enabling facile interband light emission and the fabrication of Group IV lasers. It has, however, not been possible to impart sufficient strain to Ge to reach the direct-band gap goal, because bulk Ge fractures at much lower strains. Here it is shown that very thin sheets of Ge(001), called nanomembranes (NMs), can be used to overcome this materials limitation. Germanium nanomembranes (NMs) in the range of thicknesses from 20nm to 100nm were fabricated and then transferred and mounted to a flexible substrate [a polyimide (PI) sheet]. An apparatus was developed to stress the PI/NM combination and provide for in-situ Raman measurements of the strain as a function of applied stress. This arrangement allowed for the introduction of sufficient biaxial tensile strain (>1.7%) to transform Ge to a direct-band gap material, as determined by photoluminescence (PL) measurements and theory. Appropriate shifts in the emission spectrum and increases in PL intensities were observed. The advance in this work was nanomembrane fabrication technology; i.e., making thin enough Ge sheets to accept sufficiently high levels of strain without fracture. It was of interest to determine if the strain at which fracture ultimately does occur can be raised, by evaluating factors that initiate fracture. Attempts to assess the effect of free edges (enchant

  9. Structure and electron-ion correlation of liquid germanium

    Energy Technology Data Exchange (ETDEWEB)

    Kawakita, Y. [Faculty of Sciences, Kyushu University, 4-2-1 Ropponmatsu, Fukuoka 810-8560 (Japan)]. E-mail: kawakita@rc.kyushu-u.ac.jp; Fujita, S. [Graduate School of Sciences, Kyushu University, 4-2-1 Ropponmatsu, Fukuoka 810-8560 (Japan); Kohara, S. [Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto Mikazuki-cho, Hyogo 679-5198 (Japan); Ohshima, K. [Graduate School of Sciences, Kyushu University, 4-2-1 Ropponmatsu, Fukuoka 810-8560 (Japan); Fujii, H. [Graduate School of Sciences, Kyushu University, 4-2-1 Ropponmatsu, Fukuoka 810-8560 (Japan); Yokota, Y. [Graduate School of Sciences, Kyushu University, 4-2-1 Ropponmatsu, Fukuoka 810-8560 (Japan); Takeda, S. [Faculty of Sciences, Kyushu University, 4-2-1 Ropponmatsu, Fukuoka 810-8560 (Japan)

    2005-08-15

    Structure factor of liquid germanium (Ge) has a shoulder at {theta} = 3.2 A{sup -1} in the high-momentum-transfer region of the first peak. To investigate the origin of such a non-simplicity in the structure, high energy X-ray diffraction measurements have been performed using 113.26 keV incident X-ray, at BL04B2 beamline of SPring-8. By a combination of the obtained structure factor with the reported neutron diffraction data, charge density function and electron-ion partial structure factor have been deduced. The peak position of the charge distribution is located at about 1 A, rather smaller r value than the half value of nearest neighbor distance ({approx}2.7 A), which suggests that valence electrons of liquid Ge play a role of screening electrons around a metallic ion rather than covalently bonding electrons.

  10. Young’s modulus of [111] germanium nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Maksud, M.; Palapati, N. K. R.; Subramanian, A., E-mail: asubramanian@vcu.edu [Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Yoo, J. [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Harris, C. T. [Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    2015-11-01

    This paper reports a diameter-independent Young’s modulus of 91.9 ± 8.2 GPa for [111] Germanium nanowires (Ge NWs). When the surface oxide layer is accounted for using a core-shell NW approximation, the YM of the Ge core approaches a near theoretical value of 147.6 ± 23.4 GPa. The ultimate strength of a NW device was measured at 10.9 GPa, which represents a very high experimental-to-theoretical strength ratio of ∼75%. With increasing interest in this material system as a high-capacity lithium-ion battery anode, the presented data provide inputs that are essential in predicting its lithiation-induced stress fields and fracture behavior.

  11. Nonlinear optics in germanium mid-infrared fiber material: Detuning oscillations in femtosecond mid-infrared spectroscopy

    Directory of Open Access Journals (Sweden)

    M. Ordu

    2017-09-01

    Full Text Available Germanium optical fibers hold great promise in extending semiconductor photonics into the fundamentally important mid-infrared region of the electromagnetic spectrum. The demonstration of nonlinear response in fabricated Ge fiber samples is a key step in the development of mid-infrared fiber materials. Here we report the observation of detuning oscillations in a germanium fiber in the mid-infrared region using femtosecond dispersed pump-probe spectroscopy. Detuning oscillations are observed in the frequency-resolved response when mid-infrared pump and probe pulses are overlapped in a fiber segment. The oscillations arise from the nonlinear frequency resolved nonlinear (χ(3 response in the germanium semiconductor. Our work represents the first observation of coherent oscillations in the emerging field of germanium mid-infrared fiber optics.

  12. Germanium CMOS potential from material and process perspectives: Be more positive about germanium

    Science.gov (United States)

    Toriumi, Akira; Nishimura, Tomonori

    2018-01-01

    CMOS miniaturization is now approaching the sub-10 nm level, and further downscaling is expected. This size scaling will end sooner or later, however, because the typical size is approaching the atomic distance level in crystalline Si. In addition, it is said that electron transport in FETs is ballistic or nearly ballistic, which means that the injection velocity at the virtual source is a physical parameter relevant for estimating the driving current. Channel-materials with higher carrier mobility than Si are nonetheless needed, and the carrier mobility in the channels is a parameter important with regard to increasing the injection velocity. Although the density of states in the channel has not been discussed often, it too is relevant for estimating the channel current. Both the mobility and the density of states are in principle related to the effective mass of the carrier. From this device physics viewpoint, we expect germanium (Ge) CMOS to be promising for scaling beyond the Si CMOS limit because the bulk mobility values of electrons and holes in Ge are much higher than those of electrons and holes in Si, and the electron effective mass in Ge is not much less than that in III-V compounds. There is a debate that Ge should be used for p-MOSFETs and III-V compounds for n-MOSFETs, but considering that the variability or nonuniformity of the FET performance in today’s CMOS LSIs is a big challenge, it seems that much more attention should be paid to the simplicity of the material design and of the processing steps. Nevertheless, Ge faces a number of challenges even in case that only the FET level is concerned. One of the big problems with Ge CMOS technology has been its poor performance in n-MOSFETs. While the hole mobility in p-FETs has been improved, the electron mobility in the inversion layer of Ge FETs remains a serious concern. If this is due to the inherent properties of Ge, only p-MOSFETs might be used for device applications. To make Ge CMOS devices

  13. Use of Germanium as comparator and integral monitor of neutron flux in activation analysis

    International Nuclear Information System (INIS)

    Furnari, Juan C.; Cohen, Isaac M.; Arribere, Maria A.; Kestelman, Abraham J.

    1997-01-01

    The possibility of using germanium as monitor of the thermal and epithermal components of the neutron flux, and comparator in parametric activation analysis, is discussed. The advantages and drawbacks associated to the use of this element are commented on, and the comparison with zirconium, in terms of the determination relative error, is performed. The utilisation of germanium as integral flux monitor, including the fast component of the neutron spectrum, is also discussed. Data corresponding to measurements of k 0 factor for the most relevant gamma transitions from Ge-75 and Be-77 are presented, as well as the results of the reference material analysis, employing germanium as flux monitor and comparator in a simultaneous way. (author). 8 refs., 3 figs., 2 tabs

  14. Impurity diffusion, point defect engineering, and surface/interface passivation in germanium

    KAUST Repository

    Chroneos, Alexander I.

    2012-01-26

    In recent years germanium has been emerging as a mainstream material that could have important applications in the microelectronics industry. The principle aim of this study is to review investigations of the diffusion of technologically important p- and n-type dopants as well as surface and interface passivation issues in germanium. The diffusion of impurities in germanium is interrelated to the formation of clusters whenever possible, and possibilities for point defect engineering are discussed in view of recent results. The importance of electrically active defects on the Ge surface and interfaces is addressed considering strategies to suppress them and to passivate the surfaces/interfaces, bearing in mind their importance for advanced devices. © 2012 by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Diffusion of interstitial oxygen in silicon and germanium: a hybrid functional study

    International Nuclear Information System (INIS)

    Colleoni, Davide; Pasquarello, Alfredo

    2016-01-01

    The minimum-energy paths for the diffusion of an interstitial O atom in silicon and germanium are studied through the nudged-elastic-band method and hybrid functional calculations. The reconsideration of the diffusion of O in silicon primarily serves the purpose of validating the procedure for studying the O diffusion in germanium. Our calculations show that the minimum energy path goes through an asymmetric transition state in both silicon and germanium. The stability of these transition states is found to be enhanced by the generation of unpaired electrons in the highest occupied single-particle states. Calculated energy barriers are 2.54 and 2.14 eV for Si and Ge, in very good agreement with corresponding experimental values of 2.53 and 2.08 eV, respectively. (paper)

  16. Stable functionalization of germanium surface and its application in biomolecules immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Qi [State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No.865, Changning Road, Shanghai 200050 (China); University of Chinese Academy of Sciences, No.19A, Yuquan Road, Beijing 100049 (China); Xu, Baojian [State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No.865, Changning Road, Shanghai 200050 (China); Ye, Lin [Sate Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No.865, Changning Road, Shanghai 200050 (China); University of Chinese Academy of Sciences, No.19A, Yuquan Road, Beijing 100049 (China); Tang, Teng; Huang, Shanluo; Du, Xiaowei [State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No.865, Changning Road, Shanghai 200050 (China); University of Chinese Academy of Sciences, No.19A, Yuquan Road, Beijing 100049 (China); Bian, Xiaojun; Zhang, Jishen [State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No.865, Changning Road, Shanghai 200050 (China); Di, Zengfeng, E-mail: zfdi@mail.sim.ac.cn [Sate Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No.865, Changning Road, Shanghai 200050 (China); Jin, Qinghui [State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No.865, Changning Road, Shanghai 200050 (China); Zhao, Jianlong, E-mail: jlzhao@mail.sim.ac.cn [State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, No.865, Changning Road, Shanghai 200050 (China)

    2014-10-15

    Highlights: • An effective method to immobilize biomolecules on the functionalized Ge surface. • The surface of Ge was functionalized with 11-Mercaptoundecanoic acid (11-MUA). • Stable and uniform SAMs was obtained on Ge surface after 11-MUA treatment. • The functionalized Ge was employed as substrate for protein immobilization. • Paving the way of Ge for further applications in bioelectronics field. - Abstract: As a typical semiconductor material, germanium (Ge) has the potential to be utilized in microelectronics and bioelectronics. Herein, we present a simple and effective method to immobilize biomolecules on the surface of functionalized Ge. The surface oxide of Ge was removed with the pretreatment of hydrochloric acid and the Cl-terminated Ge reacted with 11-Mercaptoundecanoic acid (11-MUA). The surface of Ge was coated with 11-MUA self-assembled monolayers (SAMs) due to the bonding reaction between the sulfhydryl group of 11-MUA and Cl-terminated Ge. Furthermore, typical biomolecule, a green fluorescent protein was chosen to be immobilized on the surface of the functionalized Ge. Contact angle analysis, atomic force microscopy and X-ray photoelectron spectroscopy were used to study the characteristics including wettability, stability, roughness and component of the functionalized Ge, respectively. Fluorescence microscopy was utilized to indicate the efficiency of protein immobilization on the surface of the functionalized Ge. With these studies, stable and uniform functionalized monolayer was obtained on the surface of Ge after 11-MUA treatment and the functionalized Ge was effectively applied in protein immobilization. Furthermore, this study may pave the way for further applications such as the integration of bioelectronics and biosensors with the attractive semiconductor material-Ge in future work.

  17. Harmonic Lattice Dynamics of Germanium

    Energy Technology Data Exchange (ETDEWEB)

    Nelin, G

    1974-07-01

    The phonon dispersion relations of the DELTA-, LAMBDA-, and SIGMA-directions of germanium at 80 K are analysed in terms of current harmonic lattice dynamical models. On the basis of this experience, a new model is proposed which gives a unified account of the strong points of the previous models. The principal elements of the presented theory are quasiparticle bond charges combined with a valence force field.

  18. Harmonic Lattice Dynamics of Germanium

    International Nuclear Information System (INIS)

    Nelin, G.

    1974-01-01

    The phonon dispersion relations of the Δ-, Λ-, and Σ-directions of germanium at 80 K are analysed in terms of current harmonic lattice dynamical models. On the basis of this experience, a new model is proposed which gives a unified account of the strong points of the previous models. The principal elements of the presented theory are quasiparticle bond charges combined with a valence force field

  19. Low temperature synthesis and electrical characterization of germanium doped Ti-based nanocrystals for nonvolatile memory

    International Nuclear Information System (INIS)

    Feng, Li-Wei; Chang, Chun-Yen; Chang, Ting-Chang; Tu, Chun-Hao; Wang, Pai-Syuan; Lin, Chao-Cheng; Chen, Min-Chen; Huang, Hui-Chun; Gan, Der-Shin; Ho, New-Jin; Chen, Shih-Ching; Chen, Shih-Cheng

    2011-01-01

    Chemical and electrical characteristics of Ti-based nanocrystals containing germanium, fabricated by annealing the co-sputtered thin film with titanium silicide and germanium targets, were demonstrated for low temperature applications of nonvolatile memory. Formation and composition characteristics of nanocrystals (NCs) at various annealing temperatures were examined by transmission electron microscopy and X-ray photon-emission spectroscopy, respectively. It was observed that the addition of germanium (Ge) significantly reduces the proposed thermal budget necessary for Ti-based NC formation due to the rise of morphological instability and agglomeration properties during annealing. NC structures formed after annealing at 500 °C, and separated well at 600 °C annealing. However, it was also observed that significant thermal desorption of Ge atoms occurs at 600 °C due to the sublimation of formatted GeO phase and results in a serious decrease of memory window. Therefore, an approach to effectively restrain Ge thermal desorption is proposed by encapsulating the Ti-based trapping layer with a thick silicon oxide layer before 600 °C annealing. The electrical characteristics of data retention in the sample with the 600 °C annealing exhibited better performance than the 500 °C-annealed sample, a result associated with the better separation and better crystallization of the NC structures.

  20. Superconductivity of tribolayers formed on germanium by friction between germanium and lead

    Energy Technology Data Exchange (ETDEWEB)

    Dukhovskoi, A.; Karapetyan, S.S.; Morozov, Y.G.; Onishchenko, A.S.; Petinov, V.I.; Ponomarev, A.N.; Silin, A.A.; Stepanov, B.M.; Tal' roze, V.L.

    1978-04-05

    A superconducting state was observed for the first time in tribolayers of germanium produced by friction of germanium with lead at 42 K. The maximum value of T/sub c/ obtained in the experiment was 19 K, which is much higher than T/sub c/ of bulk lead itself or of lead films sputtered on germanium.

  1. Topography evolution of germanium thin films synthesized by pulsed laser deposition

    Directory of Open Access Journals (Sweden)

    P. Schumacher

    2017-04-01

    Full Text Available Germanium thin films were deposited by Pulsed Laser Deposition (PLD onto single crystal Ge (100 and Si (100 substrates with a native oxide film on the surface. The topography of the surface was investigated by Atomic Force Microscopy (AFM to evaluate the scaling behavior of the surface roughness of amorphous and polycrystalline Ge films grown on substrates with different roughnesses. Roughness evolution was interpreted within the framework of stochastic rate equations for thin film growth. Here the Kardar-Parisi-Zhang equation was used to describe the smoothening process. Additionally, a roughening regime was observed in which 3-dimensional growth occurred. Diffusion of the deposited Ge adatoms controlled the growth of the amorphous Ge thin films. The growth of polycrystalline thin Ge films was dominated by diffusion processes only in the initial stage of the growth.

  2. A Moessbauer study of the germanium two-electron donor centers in PbSe

    International Nuclear Information System (INIS)

    Terukov, E.I.; Khuzhakulov, Eh.S.

    2005-01-01

    The 73 As( 73 Ge) Moessbauer emission spectroscopy is used for identification of neutral and ionized two-electron germanium centers in PbSe. It is shown that the charge state of antistructural defect 73 Ge, generating in the anion sublattice after 73 As radioactive decay, does not depend on the Fermi level position. In contrast to this, the 73 Ge center in the cation PbSe sublattice represents the electrically active substitution impurity. The emission spectra correspond to the neutral state of the ( 73 Ge 2+ ) donor center in n-type conductors and to the double ionized state of this ( 73 Ge 4+ ) center in p-type conductors [ru

  3. Self-assembly of tin wires via phase transformation of heteroepitaxial germanium-tin on germanium substrate

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wei; Li, Lingzi; Yeo, Yee-Chia, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Tok, Eng Soon [Department of Physics, National University of Singapore, Singapore 117551 (Singapore)

    2015-06-14

    This work demonstrates and describes for the first time an unusual strain-relaxation mechanism by the formation and self-assembly of well-ordered tin wires during the thermal annealing of epitaxial Ge{sub 0.83}Sn{sub 0.17}-on-Ge(001) substrate. Fully strained germanium-tin alloys (Ge{sub 0.83}Sn{sub 0.17}) were epitaxially grown on Ge(001) substrate by molecular beam epitaxy. The morphological and compositional evolution of Ge{sub 0.83}Sn{sub 0.17} during thermal annealing is studied by atomic force microscopy, X-ray diffraction, transmission electron microscopy. Under certain annealing conditions, the Ge{sub 0.83}Sn{sub 0.17} layer decomposes into two stable phases, and well-defined Sn wires that are preferentially oriented along two orthogonal 〈100〉 azimuths are formed. The formation of the Sn wires is related to the annealing temperature and the Ge{sub 0.83}Sn{sub 0.17} thickness, and can be explained by the nucleation of a grain with Sn islands on the outer front, followed by grain boundary migration. The Sn wire formation process is found to be thermally activated, and an activation enthalpy (E{sub c}) of 0.41 eV is extracted. This thermally activated phase transformation, i.e., 2D epitaxial layer to 3D wires, occurs via a mechanism akin to “cellular precipitation.” This synthesis route of Sn wires opens new possibilities for creation of nanoscale patterns at high-throughput without the need for lithography.

  4. Determination of uranium enrichment by using gamma-spectrometric methods

    International Nuclear Information System (INIS)

    Kutnyj, D.V.; Telegin, Yu.N.; Odejchuk, N.P.; Mikhailov, V.A.; Tovkanets, V.E.

    2009-01-01

    By using commercial analysis programs MGAU (LLNL, USA) and FRAM (LANL, USA) the summary error of gamma-spectrometric uranium enrichment measurements was investigated. Uranium samples with enrichments of 0,71; 4,46 and 20,1 % were measured. The coaxial high purity germanium detector (type GC) and the planar germanium detector (type LEGe) were used as gamma-radiation detectors. It was shown that experimental equipment and mathematical software available in NSC KIPT allow us to measure uranium enrichment by nondestructive method with accuracy of not worse than 2%.

  5. Secondary ion formation during electronic and nuclear sputtering of germanium

    Science.gov (United States)

    Breuer, L.; Ernst, P.; Herder, M.; Meinerzhagen, F.; Bender, M.; Severin, D.; Wucher, A.

    2018-06-01

    Using a time-of-flight mass spectrometer attached to the UNILAC beamline located at the GSI Helmholtz Centre for Heavy Ion Research, we investigate the formation of secondary ions sputtered from a germanium surface under irradiation by swift heavy ions (SHI) such as 5 MeV/u Au by simultaneously recording the mass spectra of the ejected secondary ions and their neutral counterparts. In these experiments, the sputtered neutral material is post-ionized via single photon absorption from a pulsed, intensive VUV laser. After post-ionization, the instrument cannot distinguish between secondary ions and post-ionized neutrals, so that both signals can be directly compared in order to investigate the ionization probability of different sputtered species. In order to facilitate an in-situ comparison with typical nuclear sputtering conditions, the system is also equipped with a conventional rare gas ion source delivering a 5 keV argon ion beam. For a dynamically sputter cleaned surface, it is found that the ionization probability of Ge atoms and Gen clusters ejected under electronic sputtering conditions is by more than an order of magnitude higher than that measured for keV sputtered particles. In addition, the mass spectra obtained under SHI irradiation show prominent signals of GenOm clusters, which are predominantly detected as positive or negative secondary ions. From the m-distribution for a given Ge nuclearity n, one can deduce that the sputtered material must originate from a germanium oxide matrix with approximate GeO stoichiometry, probably due to residual native oxide patches even at the dynamically cleaned surface. The results clearly demonstrate a fundamental difference between the ejection and ionization mechanisms in both cases, which is interpreted in terms of corresponding model calculations.

  6. PREFACE: 2nd Workshop on Germanium Detectors and Technologies

    Science.gov (United States)

    Abt, I.; Majorovits, B.; Keller, C.; Mei, D.; Wang, G.; Wei, W.

    2015-05-01

    The 2nd workshop on Germanium (Ge) detectors and technology was held at the University of South Dakota on September 14-17th 2014, with more than 113 participants from 8 countries, 22 institutions, 15 national laboratories, and 8 companies. The participants represented the following big projects: (1) GERDA and Majorana for the search of neutrinoless double-beta decay (0νββ) (2) SuperCDMS, EDELWEISS, CDEX, and CoGeNT for search of dark matter; (3) TEXONO for sub-keV neutrino physics; (4) AGATA and GRETINA for gamma tracking; (5) AARM and others for low background radiation counting; (5) as well as PNNL and LBNL for applications of Ge detectors in homeland security. All participants have expressed a strong desire on having better understanding of Ge detector performance and advancing Ge technology for large-scale applications. The purpose of this workshop was to leverage the unique aspects of the underground laboratories in the world and the germanium (Ge) crystal growing infrastructure at the University of South Dakota (USD) by brining researchers from several institutions taking part in the Experimental Program to Stimulate Competitive Research (EPSCoR) together with key leaders from international laboratories and prestigious universities, working on the forefront of the intensity to advance underground physics focusing on the searches for dark matter, neutrinoless double-beta decay (0νββ), and neutrino properties. The goal of the workshop was to develop opportunities for EPSCoR institutions to play key roles in the planned world-class research experiments. The workshop was to integrate individual talents and existing research capabilities, from multiple disciplines and multiple institutions, to develop research collaborations, which includes EPSCor institutions from South Dakota, North Dakota, Alabama, Iowa, and South Carolina to support multi-ton scale experiments for future. The topic areas covered in the workshop were: 1) science related to Ge

  7. Self-interstitials and Frenkel pairs in electron-irradiated germanium

    International Nuclear Information System (INIS)

    Carvalho, A.; Jones, R.; Goss, J.; Janke, C.; Coutinho, J.; Oberg, S.; Briddon, P.R.

    2007-01-01

    First principles calculations were used to study the structures and electrical levels of the self-interstitial in Ge. We considered the possibility of structural changes consequent with change in charge state and show these have important implications in the mobility and electrical activity of the defect. The theoretical model is compared to the results of low temperature electron irradiation in germanium reported in the literature

  8. Neutron Transmutation Doped (NTD) germanium thermistors for sub-mm bolometer applications

    Science.gov (United States)

    Haller, E. E.; Itoh, K. M.; Beeman, J. W.

    1996-01-01

    Recent advances in the development of neutron transmutation doped (NTD) semiconductor thermistors fabricated from natural and controlled isotopic composition germanium are reported. The near ideal doping uniformity that can be achieved with the NTD process, the device simplicity of NTD Ge thermistors and the high performance of cooled junction field effect transistor preamplifiers led to the widespread acceptance of these thermal sensors in ground-based, airborne and spaceborne radio telescopes. These features made possible the development of efficient bolometer arrays.

  9. Ultralow background germanium gamma-ray spectrometer using superclean materials and cosmic-ray anticoincidence

    International Nuclear Information System (INIS)

    Reeves, J.H.; Hensley, W.K.; Brodzinski, R.L.; Ryge, P.

    1983-10-01

    Efforts to measure the double beta decay of 76 Ge as predicted by Grand Unified Theories have resulted in the development of a high resolution germanium diode gamma-ray spectrometer with an exceptionally low background. This paper describes the development of this system and how these techniques can be utilized to significantly reduce the background in high resolution photon spectrometers at only a moderate cost

  10. Improved Limit on Neutrinoless Double-β Decay of ^{76}Ge from GERDA Phase II.

    Science.gov (United States)

    Agostini, M; Bakalyarov, A M; Balata, M; Barabanov, I; Baudis, L; Bauer, C; Bellotti, E; Belogurov, S; Bettini, A; Bezrukov, L; Biernat, J; Bode, T; Borowicz, D; Brudanin, V; Brugnera, R; Caldwell, A; Cattadori, C; Chernogorov, A; Comellato, T; D'Andrea, V; Demidova, E V; Di Marco, N; Domula, A; Doroshkevich, E; Egorov, V; Falkenstein, R; Gangapshev, A; Garfagnini, A; Grabmayr, P; Gurentsov, V; Gusev, K; Hakenmüller, J; Hegai, A; Heisel, M; Hemmer, S; Hiller, R; Hofmann, W; Hult, M; Inzhechik, L V; Janicskó Csáthy, J; Jochum, J; Junker, M; Kazalov, V; Kermaidic, Y; Kihm, T; Kirpichnikov, I V; Kirsch, A; Kish, A; Klimenko, A; Kneißl, R; Knöpfle, K T; Kochetov, O; Kornoukhov, V N; Kuzminov, V V; Laubenstein, M; Lazzaro, A; Lindner, M; Lippi, I; Lubashevskiy, A; Lubsandorzhiev, B; Lutter, G; Macolino, C; Majorovits, B; Maneschg, W; Miloradovic, M; Mingazheva, R; Misiaszek, M; Moseev, P; Nemchenok, I; Panas, K; Pandola, L; Pelczar, K; Pertoldi, L; Pullia, A; Ransom, C; Riboldi, S; Rumyantseva, N; Sada, C; Salamida, F; Schmitt, C; Schneider, B; Schönert, S; Schütz, A-K; Schulz, O; Schwingenheuer, B; Selivanenko, O; Shevchik, E; Shirchenko, M; Simgen, H; Smolnikov, A; Stanco, L; Vanhoefer, L; Vasenko, A A; Veresnikova, A; von Sturm, K; Wagner, V; Wegmann, A; Wester, T; Wiesinger, C; Wojcik, M; Yanovich, E; Zhitnikov, I; Zhukov, S V; Zinatulina, D; Zschocke, A; Zsigmond, A J; Zuber, K; Zuzel, G

    2018-03-30

    The GERDA experiment searches for the lepton-number-violating neutrinoless double-β decay of ^{76}Ge (^{76}Ge→^{76}Se+2e^{-}) operating bare Ge diodes with an enriched ^{76}Ge fraction in liquid argon. The exposure for broad-energy germanium type (BEGe) detectors is increased threefold with respect to our previous data release. The BEGe detectors feature an excellent background suppression from the analysis of the time profile of the detector signals. In the analysis window a background level of 1.0_{-0.4}^{+0.6}×10^{-3}  counts/(keV kg yr) has been achieved; if normalized to the energy resolution this is the lowest ever achieved in any 0νββ experiment. No signal is observed and a new 90% C.L. lower limit for the half-life of 8.0×10^{25}  yr is placed when combining with our previous data. The expected median sensitivity assuming no signal is 5.8×10^{25}  yr.

  11. High bit rate germanium single photon detectors for 1310nm

    Science.gov (United States)

    Seamons, J. A.; Carroll, M. S.

    2008-04-01

    There is increasing interest in development of high speed, low noise and readily fieldable near infrared (NIR) single photon detectors. InGaAs/InP Avalanche photodiodes (APD) operated in Geiger mode (GM) are a leading choice for NIR due to their preeminence in optical networking. After-pulsing is, however, a primary challenge to operating InGaAs/InP single photon detectors at high frequencies1. After-pulsing is the effect of charge being released from traps that trigger false ("dark") counts. To overcome this problem, hold-off times between detection windows are used to allow the traps to discharge to suppress after-pulsing. The hold-off time represents, however, an upper limit on detection frequency that shows degradation beginning at frequencies of ~100 kHz in InGaAs/InP. Alternatively, germanium (Ge) single photon avalanche photodiodes (SPAD) have been reported to have more than an order of magnitude smaller charge trap densities than InGaAs/InP SPADs2, which allowed them to be successfully operated with passive quenching2 (i.e., no gated hold off times necessary), which is not possible with InGaAs/InP SPADs, indicating a much weaker dark count dependence on hold-off time consistent with fewer charge traps. Despite these encouraging results suggesting a possible higher operating frequency limit for Ge SPADs, little has been reported on Ge SPAD performance at high frequencies presumably because previous work with Ge SPADs has been discouraged by a strong demand to work at 1550 nm. NIR SPADs require cooling, which in the case of Ge SPADs dramatically reduces the quantum efficiency of the Ge at 1550 nm. Recently, however, advantages to working at 1310 nm have been suggested which combined with a need to increase quantum bit rates for quantum key distribution (QKD) motivates examination of Ge detectors performance at very high detection rates where InGaAs/InP does not perform as well. Presented in this paper are measurements of a commercially available Ge APD

  12. Electron, hole and exciton self-trapping in germanium doped silica glass from DFT calculations with self-interaction correction

    International Nuclear Information System (INIS)

    Du Jincheng; Rene Corrales, L.; Tsemekhman, Kiril; Bylaska, Eric J.

    2007-01-01

    Density functional theory (DFT) calculations were employed to understand the refractive index change in germanium doped silica glasses for the trapped states of electronic excitations induced by UV irradiation. Local structure relaxation and excess electron density distribution were calculated upon self-trapping of an excess electron, hole, and exciton in germanium doped silica glass. The results show that both the trapped exciton and excess electron are highly localized on germanium ion and, to some extent, on its oxygen neighbors. Exciton self-trapping is found to lead to the formation of a Ge E' center and a non-bridging hole center. Electron trapping changes the GeO 4 tetrahedron structure into trigonal bi-pyramid with the majority of the excess electron density located along the equatorial line. The self-trapped hole is localized on bridging oxygen ions that are not coordinated to germanium atoms that lead to elongation of the Si-O bonds and change of the Si-O-Si bond angles. We carried out a comparative study of standard DFT versus DFT with a hybrid PBE0 exchange and correlation functional. The results show that the two methods give qualitatively similar relaxed structure and charge distribution for electron and exciton trapping in germanium doped silica glass; however, only the PBE0 functional produces the self-trapped hole

  13. Preparation of special purity Ge - S - I and Ge - Se - I glasses

    Science.gov (United States)

    Velmuzhov, A. P.; Sukhanov, M. V.; Shiryaev, V. S.; Kotereva, T. V.; Snopatin, G. E.; Churbanov, M. F.

    2017-05-01

    The paper considers the new approaches for the production of special pure Ge - S - I and Ge - Se - I glasses via the germanium(IV) iodide, germanium(II) sulfide, as well as the Ge2S3, Ge2S3I2 and Ge2Se3I2 glassy alloys. The glass samples containing 0.03-0.17 ppm(wt) hydrogen impurity in the form of SH-group, 0.04-0.15 ppm(wt) hydrogen impurity in the form of SeH-group, and 0.5-7.8 ppm(wt) oxygen impurity in the form of Ge-O were produced. Using a crucible technique, the single-index [GeSe4]95I5 glass fibers of 300-400 μm diameter were drawn. The minimum optical losses in the best fiber were 1.7 dB/m at a wavelength of 5.5 μm; the background optical losses were within 2-3 dB/m in the spectral range of 2.5-8 μm.

  14. Vertical Ge photodetector base on InP taper waveguide

    Science.gov (United States)

    Amiri, Iraj Sadegh; Ariannejad, M. M.; Azzuhri, S. R. B.; Anwar, T.; Kouhdaragh, V.; Yupapin, P.

    2018-06-01

    In this work, simulation is conducted to investigate Ge photodetectors monolithically integrated on Si chip. The performance of vertical Germanium photodetector with FDTD Solutions (optical simulation) and electrical simulation has been studied. Selective heteroepitaxy of Ge is functioned in the monolithic integration of Ge photodetectors. The potential of CMOS-compatible monolithic integration of Ge as photodetector is investigated and the performance optimization is presented. Additionally, the investigation is extended to electrical part, particularly in the conversion efficiency as well as operation under low supplied voltage condition.

  15. Information on real-structure phenomena in metastable GeTe-rich germanium antimony tellurides (GeTe){sub n}Sb{sub 2}Te{sub 3} (n ≥ 3) by semi-quantitative analysis of diffuse X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Urban, Philipp; Oeckler, Oliver [Leipzig Univ. (Germany). Faculty of Chemistry and Mineralogy; Schneider, Matthias N.; Seemann, Marten [Munich Univ. (Germany). Dept. of Chemistry; Wright, Jonathan P. [ESRF - The European Synchrotron, Grenoble (France)

    2015-07-01

    Quenching cubic high-temperature polymorphs of (GeTe){sub n}Sb{sub 2}Te{sub 3} (n ≥ 3) yields metastable phases whose average structures can be approximated by the rocksalt type with 1/(n + 3) cation vacancies per anion. Corresponding diffraction patterns are a superposition of intensities from individual twin domains with trigonal average structure but pseudo-cubic metrics. Their four orientations are mirrored in structured diffuse streaks that interconnect Bragg reflections along the [001] directions of individual disordered trigonal domains. These streaks exhibit a ''comet-like'' shape with a maximum located at the low-angle side of Bragg positions (''comet head'') accompanied by a diffuse ''comet tail''. 2D extended cation defect ordering leads to parallel but not equidistantly spaced planar faults. Based on a stacking fault approach, the diffuse scattering was simulated with parameters that describe the overall metrics, the concentration and distribution of cation defect layers, atom displacements in their vicinity and the stacking sequence of Te atom layers around the planar defects. These parameters were varied in order to derive simple rules for the interpretation of the diffuse scattering. The distance between Bragg positions and ''comet heads'' increases with the frequency of planar faults. A sharp distance distribution of the planar faults leads to an intensity modulation along the ''comet tail'' which for low values of n approximates superstructure reflections. The displacement of atom layers towards the planar defects yields ''comets'' on the low-angle side of Bragg positions. A rocksalt-type average structure is only present if the planar defects correspond to missing cation layers in the ''cubic'' ABC stacking sequence of the Te atom layers. An increasing amount of hexagonal ABA transitions around the defect

  16. Transport in silicon-germanium heterostructures

    International Nuclear Information System (INIS)

    Chrastina, Daniel

    2001-01-01

    The work presented here describes the electrical characterization of n- and p-type strained silicon-germanium systems. Theories of quantum transport m low magnetic fields at low temperature are discussed m terms of weak-localization: the traditional theory is shown not to account for the dephasing in a 2-dimensional hole gas behaving in a metallic manner and emergent alternative theories, while promising, require refinement. The mobility as a function of sheet density is measured in a p-type pseudomorphic Si 0.5 Ge 0.5 across the temperature range 350mK-282K; it is shown that calculations of the mobility based on semi-classical scattering mechanisms fail below 10K where quantum transport effects become relevant. A room temperature Hall scattering factor has been extracted. A new functional form has been presented to fit the resistivity as a function of temperature, below 20K: traditional theories of screening and weak localization appear not to be applicable. It is also demonstrated that simple protection circuitry is essential if commercial-scale devices are to be meaningfully investigated. Mobility spectrum analysis is performed on an n-type strained-silicon device. Established analysis methods are discussed and a new method is presented based on the Bryan's Algorithm approach to maximum entropy. The breakdown of the QHE is also investigated: the critical current density compares well to that predicted by an existing theory. Finally, devices in which both electron and hole gases can be induced are investigated. However, it is shown that the two cannier species never co-exist. Design rules are presented which may allow more successful structures to be created. Results are presented which demonstrate the success and the utility of implanted contacts which selectively reach different regions of the structure. (author)

  17. Ultra Shallow Arsenic Junctions in Germanium Formed by Millisecond Laser Annealing

    DEFF Research Database (Denmark)

    Hellings, G.; Rosseel, E.; Simoen, E.

    2011-01-01

    Millisecond laser annealing is used to fabricate ultra shallow arsenic junctions in preamorphized and crystalline germanium, with peak temperatures up to 900 degrees C. At this temperature, As indiffusion is observed while yielding an electrically active concentration up to 5.0 x 10(19) cm(-3......) for a junction depth of 31 nm. Ge preamorphization and the consecutive solid phase epitaxial regrowth are shown to result in less diffusion and increased electrical activation. The recrystallization of the amorphized Ge layer during laser annealing is studied using transmission electron microscopy...

  18. Analysis of switching characteristics for negative capacitance ultra-thin-body germanium-on-insulator MOSFETs

    Science.gov (United States)

    Pi-Ho Hu, Vita; Chiu, Pin-Chieh

    2018-04-01

    The impact of device parameters on the switching characteristics of negative capacitance ultra-thin-body (UTB) germanium-on-insulator (NC-GeOI) MOSFETs is analyzed. NC-GeOI MOSFETs with smaller gate length (L g), EOT, and buried oxide thickness (T box) and thicker ferroelectric layer thickness (T FE) exhibit larger subthreshold swing improvements over GeOI MOSFETs due to better capacitance matching. Compared with GeOI MOSFETs, NC-GeOI MOSFETs exhibit better switching time due to improvements in effective drive current (I eff) and subthreshold swing. NC-GeOI MOSFET exhibits larger ST improvements at V dd = 0.3 V (-82.9%) than at V dd = 0.86 V (-9.7%), because NC-GeOI MOSFET shows 18.2 times higher I eff than the GeOI MOSFET at V dd = 0.3 V, while 2.5 times higher I eff at V dd = 0.86 V. This work provides the device design guideline of NC-GeOI MOSFETs for ultra-low power applications.

  19. Lithium effects on the mechanical and electronic properties of germanium nanowires

    Science.gov (United States)

    González-Macías, A.; Salazar, F.; Miranda, A.; Trejo-Baños, A.; Pérez, L. A.; Carvajal, E.; Cruz-Irisson, M.

    2018-04-01

    Semiconductor nanowire arrays promise rapid development of a new generation of lithium (Li) batteries because they can store more Li atoms than conventional crystals due to their large surface areas. During the charge-discharge process, the electrodes experience internal stresses that fatigue the material and limit the useful life of the battery. The theoretical study of electronic and mechanical properties of lithiated nanowire arrays allows the designing of electrode materials that could improve battery performance. In this work, we present a density functional theory study of the electronic band structure, formation energy, binding energy, and Young’s modulus (Y) of hydrogen passivated germanium nanowires (H-GeNWs) grown along the [111] and [001] crystallographic directions with surface and interstitial Li atoms. The results show that the germanium nanowires (GeNWs) with surface Li atoms maintain their semiconducting behavior but their energy gap size decreases when the Li concentration grows. In contrast, the GeNWs can have semiconductor or metallic behavior depending on the concentration of the interstitial Li atoms. On the other hand, Y is an indicator of the structural changes that GeNWs suffer due to the concentration of Li atoms. For surface Li atoms, Y stays almost constant, whereas for interstitial Li atoms, the Y values indicate important structural changes in the GeNWs.

  20. The Majorana Experiment: a Straightforward Neutrino Mass Experiment Using The Double-Beta Decay of Ge-76

    International Nuclear Information System (INIS)

    Miley, Harry S.; Y Suzuki; M Nakahata; Y Itow; M Shiozawa; Y Obayashi

    2004-01-01

    The Majorana Experiment proposes to measure the effective mass of the electron neutrino to as low as 0.02 eV using well-tested technology. A half life of about 4E27 y, corresponding to a mass range of [0.02 - 0.07] eV can be reached by operating 500 kg of germanium enriched to 86% in Ge-76 deep underground. Radiological backgrounds of cosmogenic or primordial origin will be greatly reduced by ultra-low background screening of detector, structural, and shielding materials, by chemical processing of materials, and by electronic rejection of multi-site events in the detector. Electronic background reduction is achieved with pulse shape analysis, detector segmentation, and detector-to detector coincidence rejection

  1. GE NANOCLUSTERS IN PLANAR GLASS WAVEGUIDES DEPOSITED BY PECVD

    DEFF Research Database (Denmark)

    Haiyan, Ou; Olsen, Johnny H.; Rottwitt, Karsten

    2004-01-01

    Germanium (Ge) has been widely used as the dopant in the core layer of planar glass waveguides to increase the refractive index because it gives a small propagation loss. Plasma enhanced chemical vapour deposition (PECVD) and flame hydrolysis deposition (FHD) are two main material deposition meth...

  2. GeSn Based Near and Mid Infrared Heterostructure Detectors

    Science.gov (United States)

    2018-02-07

    prestigious journals. 15.  SUBJECT TERMS Plasmonic Enhancement, Metal Nanostructures, CMOS, Photodetectors, Germanium-Tin Diode, IR Focal Plane Array...following features: (1) ease of manufacture in a foundry via a simple epitaxial structure, (2) end- fire coupling into on-chip transparent Ge or Si

  3. Characterization of Ge-nanocrystal films with photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Bostedt, C.; Buuren, T. van; Willey, T.M.; Nelson, A.J.; Franco, N.; Moeller, T.; Terminello, L.J.

    2003-01-01

    The Ge 3d core-levels of germanium nanocrystal films have been investigated by means of photoelectron spectroscopy. The experiments indicate bulk-like coordinated atoms in the nanocrystals and suggest structured disorder on the nanoparticle surface. The results underline the importance of the surface on the overall electronic structure of this class of nanostructured materials

  4. Ion-beam induced structure modifications in amorphous germanium

    International Nuclear Information System (INIS)

    Steinbach, Tobias

    2012-01-01

    Object of the present thesis was the systematic study of ion-beam induced structure modifications in amorphous germanium (a-Ge) layers due to low- (LEI) and high-energetic (SHI) ion irradiation. The LEI irradiation of crystalline Ge (c-Ge) effects because the dominating nuclear scattering of the ions on the solid-state atoms the formation of a homogeneous a-Ge Layer. Directly on the surface for fluences of two orders of magnitude above the amorphization fluence the formation of stable cavities independently on the irradiation conditions was observed. For the first time for the ion-beam induced cavity formation respectively for the steady expansion of the porous layer forming with growing fluence a linear dependence on the energy ε n deposed in nuclear processes was detected. Furthermore the formation of buried cavities was observed, which shows a dependence on the type of ions. While in the c-Ge samples in the range of the high electronic energy deposition no radiation defects, cavities, or plastic deformations were observed, the high electronic energy transfer in the 3.1 μm thick pre-amorphized a-Ge surface layers leads to the formation of randomly distributed cavities. Basing on the linear connection between cavity-induced vertical volume expansion and the fluence determined for different energy transfers for the first time a material-specific threshold value of ε e HRF =(10.5±1.0) kev nm -1 was determined, above which the ion-beam induced cavity formation in a-Ge sets on. The anisotropic plastic deformation of th a-Ge layer superposed at inclined SHI irradiation on the cavity formation was very well described by an equation derived from the viscoelastic Maxwell model, but modified under regardment of the experimental results. The positive deformation yields determined thereby exhibit above a threshold value for the ion-beam induced plastic deformation ε e S a =(12±2) keV nm -1 for the first time extracted for a Ge the characteristic linear behaviour of the

  5. NTD germanium: a novel material for low-temperature bolometers

    International Nuclear Information System (INIS)

    Haller, E.E.; Palaio, N.P.; Rodder, M.; Hansen, W.L.; Kreysa, E.

    1982-06-01

    Six samples of ultra-pure (absolute value N/sub A/ - N/sub D/ absolute value less than or equal to 10 11 cm -3 ), single-crystal germanium have been neutron transmutation doped with neutron doses between 7.5 x 10 16 and 1.88 x 10 18 cm -2 . After thermal annealing at 400 0 C for six hours in a pure argon atmosphere, the samples have been characterized with Hall effect and resistivity measurements between 300 and 0.3 K. Our results show that the resistivity in the low temperature, hopping conduction regime can be approximated with rho = rho 0 exp(Δ/T). The three more heavily doped samples show values for rho 0 and Δ ranging from 430 to 3.3 Ω cm and from 4.9 to 2.8 K, respectively. The excellent reproducibility of neutron transmutation doping and the values of rho 0 and Δ make NTD Ge a prime candidate for the fabrication of low temperature, low noise bolometers. The large variation in the tabulated values of the thermal neutron cross sections for the different germanium isotopes makes it clear that accurate measurements of these cross-sections for well defined neutron energy spectra would be highly desirable

  6. Study and characterization of porous germanium for radiometric measurements

    Energy Technology Data Exchange (ETDEWEB)

    Akkari, E.; Benachour, Z.; Touayar, O.; Benbrahim, J. [Activites de Recherche, Metrologie des Rayonnements, Institut National des Sciences Appliquees et de Technologie, INSAT, Tunis (Tunisia); Aouida, S.; Bessais, B. [Laboratoire de Nanomateriaux et des Systemes de l' Energie, LaNSE, Centre de Recherche et des Technologies de l' Energie, CRTEn, Hammam-Lif (Tunisia)

    2009-07-15

    The aim of this article is to study and realize a new detector based on a porous germanium (pGe) photodiode to be used as a standard for radiometric measurement in the wavelength region between 800 nm and 1700 nm. We present the development and characterization of a porous structure realized on a single-crystal substrate of p-type germanium (Ga doped) and of crystallographic orientation (100). The obtained structure allows, on the one hand, to trap the incident radiation, and on the other hand, to minimize the fluctuations of the front-face reflection coefficient of the photodiode. The first studies thus made show that it is possible to optimize, respectively, the electrical current density and the electrochemical operation time necessary for obtaining exploitable porous structures. The obtained results show that for 50 mA/cm{sup 2} and 5 min as operational parameters, we obtain a textured aspect of the porous samples that present a pyramidal form. The reflectivity study of the front surface shows a constant value of around 38% in a spectral range between 800 nm and 1700 nm approximately. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Influence of silicon dangling bonds on germanium thermal diffusion within SiO{sub 2} glass

    Energy Technology Data Exchange (ETDEWEB)

    Barba, D.; Martin, F.; Ross, G. G. [INRS Centre for Energy, Materials and Telecommunications, 1650 Boul. Lionel-Boulet, Varennes, Québec J3X 1S2 (Canada); Cai, R. S.; Wang, Y. Q. [The Cultivation Base for State Key Laboratory, Qingdao University, Qingdao 266071 (China); Demarche, J.; Terwagne, G. [LARN, Centre de Recherche en Physique de la Matière et du Rayonnement (PMR), University of Namur (FUNDP), B-5000 Namur (Belgium); Rosei, F. [INRS Centre for Energy, Materials and Telecommunications, 1650 Boul. Lionel-Boulet, Varennes, Québec J3X 1S2 (Canada); Center for Self-Assembled Chemical Structures, McGill University, Montreal, Quebec H3A 2K6 (Canada)

    2014-03-17

    We study the influence of silicon dangling bonds on germanium thermal diffusion within silicon oxide and fused silica substrates heated to high temperatures. By using scanning electron microscopy and Rutherford backscattering spectroscopy, we determine that the lower mobility of Ge found within SiO{sub 2}/Si films can be associated with the presence of unsaturated SiO{sub x} chemical bonds. Comparative measurements obtained by x-ray photoelectron spectroscopy show that 10% of silicon dangling bonds can reduce Ge desorption by 80%. Thus, the decrease of the silicon oxidation state yields a greater thermal stability of Ge inside SiO{sub 2} glass, which could enable to considerably extend the performance of Ge-based devices above 1300 K.

  8. Formation and characterization of varied size germanium nanocrystals by electron microscopy, Raman spectroscopy, and photoluminescence

    DEFF Research Database (Denmark)

    Ou, Haiyan; Ou, Yiyu; Liu, Chuan

    2011-01-01

    Germanium nanocrystals are being extensively examined. Their unique optical properties (brought about by the quantum confinement effect) could potentially be applied in wide areas of nonlinear optics, light emission and solid state memory etc. In this paper, Ge nanocrystals embedded in a SiO2...... matrix were formed by complementary metal-oxide-semiconductor compatible technology, e.g. plasma enhanced chemical vapour deposition and annealing. Different sizes of the Ge nanocrystals were prepared and analyzed by transmission electron microscopy with respect to their size, distribution...... and crystallization. The samples of different size Ge nanocrystals embedded in the SiO2 matrix were characterized by Raman spectroscopy and photoluminescence. Interplayed size and strain effect of Ge nanocystals was demonstrated by Raman spectroscopy after excluding the thermal effect with proper excitation laser...

  9. Investigation of electron exchange between neutral and ionized centers of germanium in PbSe

    International Nuclear Information System (INIS)

    Terukov, I.E.; Khuzhakulov, Eh.S.

    2005-01-01

    The 73 As( 73 Ge) emission Moessbauer spectroscopy is applied to study the electron exchange between neutral ionized states of the germanium donor center in PbSe. It is shown that the charge state of the antistructural 73 Ge defect, generating in the anion PbSe sublattice after 73 As radioactive decay, does not depend on the Fermi level location. In contrast to this, the 73 Ge center in the cation PbSe sublattice is the isoelectronic substitution impurity. The analysis of emission Moessbauer spectra of p-type PbSe: 73 As testifies about the presence of the fast electron exchange between neutral and ionized donor Ge centers in PbSe [ru

  10. Zone refining high-purity germanium

    International Nuclear Information System (INIS)

    Hubbard, G.S.; Haller, E.E.; Hansen, W.L.

    1977-10-01

    The effects of various parameters on germanium purification by zone refining have been examined. These parameters include the germanium container and container coatings, ambient gas and other operating conditions. Four methods of refining are presented which reproducibly yield 3.5 kg germanium ingots from which high purity (vertical barN/sub A/ - N/sub D/vertical bar less than or equal to2 x 10 10 cm -3 ) single crystals can be grown. A qualitative model involving binary and ternary complexes of Si, O, B, and Al is shown to account for the behavior of impurities at these low concentrations

  11. LArGe. A liquid argon scintillation veto for GERDA

    International Nuclear Information System (INIS)

    Heisel, Mark

    2011-01-01

    LArGe is a GERDA low-background test facility to study novel background suppression methods in a low-background environment, for possible applications in the GERDA experiment. GERDA searches for the neutrinoless double-beta decay in 76 Ge, by operating naked germanium detectors submersed into 65 m 3 of liquid argon. Similarly, LArGe runs Ge-detectors in 1 m 3 (1.4 tons) of liquid argon, which in addition is instrumented with photomultipliers to detect argon scintillation light. The light is used in anti-coincidence with the germanium detectors, to effectively suppress background events that deposit energy in the liquid argon. This work adresses the design, construction, and commissioning of LArGe. The background suppression efficiency has been studied in combination with a pulse shape discrimination (PSD) technique for various sources, which represent characteristic backgrounds to GERDA. Suppression factors of a few times 10 3 have been achieved. First background data of LArGe (without PSD) yield a background index of (0.12-4.6).10 -2 cts/(keV.kg.y) (90% c.l.), which is at the level of the Gerda phase I design goal. Furthermore, for the first time we measure the natural 42 Ar abundance (in parallel to Gerda), and have indication for the 2νββ-decay in natural germanium. (orig.)

  12. LArGe. A liquid argon scintillation veto for GERDA

    Energy Technology Data Exchange (ETDEWEB)

    Heisel, Mark

    2011-04-13

    LArGe is a GERDA low-background test facility to study novel background suppression methods in a low-background environment, for possible applications in the GERDA experiment. GERDA searches for the neutrinoless double-beta decay in {sup 76}Ge, by operating naked germanium detectors submersed into 65 m{sup 3} of liquid argon. Similarly, LArGe runs Ge-detectors in 1 m{sup 3} (1.4 tons) of liquid argon, which in addition is instrumented with photomultipliers to detect argon scintillation light. The light is used in anti-coincidence with the germanium detectors, to effectively suppress background events that deposit energy in the liquid argon. This work adresses the design, construction, and commissioning of LArGe. The background suppression efficiency has been studied in combination with a pulse shape discrimination (PSD) technique for various sources, which represent characteristic backgrounds to GERDA. Suppression factors of a few times 10{sup 3} have been achieved. First background data of LArGe (without PSD) yield a background index of (0.12-4.6).10{sup -2} cts/(keV.kg.y) (90% c.l.), which is at the level of the Gerda phase I design goal. Furthermore, for the first time we measure the natural {sup 42}Ar abundance (in parallel to Gerda), and have indication for the 2{nu}{beta}{beta}-decay in natural germanium. (orig.)

  13. Isotopic germanium targets for high beam current applications at GAMMASPHERE

    International Nuclear Information System (INIS)

    Greene, J. P.; Lauritsen, T.

    2000-01-01

    The creation of a specific heavy ion residue via heavy ion fusion can usually be achieved through a number of beam and target combinations. Sometimes it is necessary to choose combinations with rare beams and/or difficult targets in order to achieve the physics goals of an experiment. A case in point was a recent experiment to produce 152 Dy at very high spins and low excitation energy with detection of the residue in a recoil mass analyzer. Both to create the nucleus cold and with a small recoil-cone so that the efficiency of the mass analyzer would be high, it was necessary to use the 80 Se on 76 Ge reaction rather than the standard 48 Ca on 108 Pd reaction. Because the recoil velocity of the 152 Dy residues was very high using this symmetric reaction (5% v/c), it was furthermore necessary to use a stack of two thin targets to reduce the Doppler broadening. Germanium targets are fragile and do not withstand high beam currents, therefore the 76 Ge target stacks were mounted on a rotating target wheel. A description of the 76 Ge target stack preparation will be presented and the target performance described

  14. On the origin of anisotropic lithiation in crystalline silicon over germanium: A first principles study

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Chia-Yun [Materials Science and Engineering Program, University of Texas at Austin, Austin, TX 78712 (United States); Hwang, Gyeong S., E-mail: gshwang@che.utexas.edu [Materials Science and Engineering Program, University of Texas at Austin, Austin, TX 78712 (United States); Department of Chemical Engineering, University of Texas at Austin, Austin, TX 78712 (United States)

    2014-12-30

    Graphical abstract: - Highlights: • We examine the underlying reasons for the anisotropic lithiation of Si over Ge in the crystalline phase. • Crystalline Si is lithiated in a layer-by-layer fashion, yielding a sharp amorphous–crystalline interface. • Lithiated c-Ge exhibits a graded lithiation front, which proceeds much faster than that in c-Si. • Lithiation behavior tends to be subject to the stiffness and dynamics of the host matrix. • We reveal the origin and extended impacts of the anisotropic Si vs. isotropic Ge lithiation. - Abstract: Silicon (Si) and germanium (Ge) are both recognized as a promising anode material for high-energy lithium-ion batteries. Si is abundant and best known for its superior gravimetric energy storage capacity, while Ge exhibits faster charge/discharge rates and better capacity retention. Recently, it was discovered that Si lithiation exhibits strong orientation dependence while Ge lithiation proceeds isotropically, although they have the same crystalline structure. To better understand the underlying reasons behind these distinctive differences, we examine and compare the lithiation behaviors at the Li{sub 4}Si/c-Si(1 1 0) and Li{sub 4}Ge/c-Ge(1 1 0) model systems using ab initio molecular dynamics simulations. In comparison to lithiated c-Si, where a sharp amorphous–crystalline interface remains and advances rather slowly, lithiated c-Ge tends to loose its crystallinity rapidly, resulting in a graded lithiation front of fast propagation speed. Analysis of the elastic responses and dynamics of the host Si and Ge lattices clearly demonstrate that from the beginning of the lithiation process, Ge lattice responds with more significant weakening as compared to the rigid Si lattice. Moreover, the more flexible Ge lattice is found to undergo facile atomic rearrangements during lithiation, overshadowing the original crystallographic characteristic. These unique properties of Ge thereby contribute synergistically to the rapid

  15. Alleviation of fermi-level pinning effect at metal/germanium interface by the insertion of graphene layers

    International Nuclear Information System (INIS)

    Baek, Seung-heon Chris; Seo, Yu-Jin; Oh, Joong Gun; Albert Park, Min Gyu; Bong, Jae Hoon; Yoon, Seong Jun; Lee, Seok-Hee; Seo, Minsu; Park, Seung-young; Park, Byong-Guk

    2014-01-01

    In this paper, we report the alleviation of the Fermi-level pinning on metal/n-germanium (Ge) contact by the insertion of multiple layers of single-layer graphene (SLG) at the metal/n-Ge interface. A decrease in the Schottky barrier height with an increase in the number of inserted SLG layers was observed, which supports the contention that Fermi-level pinning at metal/n-Ge contact originates from the metal-induced gap states at the metal/n-Ge interface. The modulation of Schottky barrier height by varying the number of inserted SLG layers (m) can bring about the use of Ge as the next-generation complementary metal-oxide-semiconductor material. Furthermore, the inserted SLG layers can be used as the tunnel barrier for spin injection into Ge substrate for spin-based transistors.

  16. Specific features of phase transformations in germanium monotelluride

    International Nuclear Information System (INIS)

    Bigvava, A.D.; Gabedava, A.A.; Kunchuliya, Eh.D.; Shvangiradze, R.R.

    1981-01-01

    Phase transformations in germanium monotelluride are studied . using DRON-0.5 and DRON-1 plants with high-temperature chamber GPVT-1500 at Cu, Ksub(α) radiation. It is shown that in the whole homogeneity range α GeTe is a metastable phase which is formed under the conditions of fast cooling of alloy from temperatures >=Tsub(cub) (temperature of transition in cubic crystal system). An equilibrium γ-phase is obtained by annealing of dispersed powders and metal-ceramic specimens of alloys with 50.3; 50.6; 50.9 at % Te. Lattice parameters of rhombic γ-phase do not depend on tellurium content in initial α- phase. α→γ transformation is observed at any temperature less than Tsub(cub) with the change of alloy composition, namely tellurium precipitation. γ-phase transforms into β at higher temperatures than α-phase [ru

  17. Si-Based Germanium Tin Semiconductor Lasers for Optoelectronic Applications

    Science.gov (United States)

    Al-Kabi, Sattar H. Sweilim

    Silicon-based materials and optoelectronic devices are of great interest as they could be monolithically integrated in the current Si complementary metal-oxide-semiconductor (CMOS) processes. The integration of optoelectronic components on the CMOS platform has long been limited due to the unavailability of Si-based laser sources. A Si-based monolithic laser is highly desirable for full integration of Si photonics chip. In this work, Si-based germanium-tin (GeSn) lasers have been demonstrated as direct bandgap group-IV laser sources. This opens a completely new avenue from the traditional III-V integration approach. In this work, the material and optical properties of GeSn alloys were comprehensively studied. The GeSn films were grown on Ge-buffered Si substrates in a reduced pressure chemical vapor deposition system with low-cost SnCl4 and GeH4 precursors. A systematic study was done for thin GeSn films (thickness 400 nm) with Sn composition 5 to 17.5%. The room temperature photoluminescence (PL) spectra were measured that showed a gradual shift of emission peaks towards longer wavelength as Sn composition increases. Strong PL intensity and low defect density indicated high material quality. Moreover, the PL study of n-doped samples showed bandgap narrowing compared to the unintentionally p-doped (boron) thin films with similar Sn compositions. Finally, optically pumped GeSn lasers on Si with broad wavelength coverage from 2 to 3 mum were demonstrated using high-quality GeSn films with Sn compositions up to 17.5%. The achieved maximum Sn composition of 17.5% broke the acknowledged Sn incorporation limit using similar deposition chemistry. The highest lasing temperature was measured at 180 K with an active layer thickness as thin as 270 nm. The unprecedented lasing performance is due to the achievement of high material quality and a robust fabrication process. The results reported in this work show a major advancement towards Si-based electrically pumped mid

  18. Development of segmented germanium detectors for neutrinoless double beta decay experiments

    International Nuclear Information System (INIS)

    Liu, Jing

    2009-01-01

    The results from neutrino oscillation experiments indicate that at least two neutrinos have mass. However, the value of the masses and whether neutrinos and anti-neutrinos are identical, i.e., Majorana particles, remain unknown. Neutrinoless double beta decay experiments can help to improve our understanding in both cases and are the only method currently possible to tackle the second question. The GERmanium Detector Array (GERDA) experiment, which will search for the neutrinoless double beta decay of 76 Ge, is currently under construction in Hall A of the INFN Gran Sasso National Laboratory (LNGS), Italy. In order to achieve an extremely low background level, segmented germanium detectors are considered to be operated directly in liquid argon which serves simultaneously as cooling and shielding medium. Several test cryostats were built at the Max-Planck-Institut fuer Physik in Muenchen to operate segmented germanium detectors both in vacuum and submerged in cryogenic liquid. The performance and the background discrimination power of segmented germanium detectors were studied in detail. It was proven for the first time that segmented germanium detectors can be operated stably over long periods submerged in a cryogenic liquid. It was confirmed that the segmentation scheme employed does well in the identification of photon induced background and demonstrated for the first time that also neutron interactions can be identified. The C++ Monte Carlo framework, MaGe (Majorana-GERDA), is a joint development of the Majorana and GERDA collaborations. It is based on GEANT4, but tailored especially to simulate the response of ultra-low background detectors to ionizing radiation. The predictions of the simulation were veri ed to be accurate for a wide range of conditions. Some shortcomings were found and corrected. Pulse shape analysis is complementary to segmentation in identifying background events. Its efficiency can only be correctly determined using reliable pulse shape

  19. Development of segmented germanium detectors for neutrinoless double beta decay experiments

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jing

    2009-06-09

    The results from neutrino oscillation experiments indicate that at least two neutrinos have mass. However, the value of the masses and whether neutrinos and anti-neutrinos are identical, i.e., Majorana particles, remain unknown. Neutrinoless double beta decay experiments can help to improve our understanding in both cases and are the only method currently possible to tackle the second question. The GERmanium Detector Array (GERDA) experiment, which will search for the neutrinoless double beta decay of {sup 76}Ge, is currently under construction in Hall A of the INFN Gran Sasso National Laboratory (LNGS), Italy. In order to achieve an extremely low background level, segmented germanium detectors are considered to be operated directly in liquid argon which serves simultaneously as cooling and shielding medium. Several test cryostats were built at the Max-Planck-Institut fuer Physik in Muenchen to operate segmented germanium detectors both in vacuum and submerged in cryogenic liquid. The performance and the background discrimination power of segmented germanium detectors were studied in detail. It was proven for the first time that segmented germanium detectors can be operated stably over long periods submerged in a cryogenic liquid. It was confirmed that the segmentation scheme employed does well in the identification of photon induced background and demonstrated for the first time that also neutron interactions can be identified. The C++ Monte Carlo framework, MaGe (Majorana-GERDA), is a joint development of the Majorana and GERDA collaborations. It is based on GEANT4, but tailored especially to simulate the response of ultra-low background detectors to ionizing radiation. The predictions of the simulation were veri ed to be accurate for a wide range of conditions. Some shortcomings were found and corrected. Pulse shape analysis is complementary to segmentation in identifying background events. Its efficiency can only be correctly determined using reliable pulse

  20. Metal induced crystallization of silicon germanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gjukic, M.

    2007-05-15

    In the framework of this thesis the applicability of the aluminium-induced layer exchange on binary silicon germanium alloys was studied. It is here for the first time shown that polycrstalline silicon-germanium layers can be fabricated over the whole composition range by the aluminium-induced layer exchange. The experimental results prove thet the resulting material exhibits a polycrystalline character with typocal grain sizes of 10-100 {mu}m. Raman measurements confirm that the structural properties of the resulting layers are because of the large crystallites more comparable with monocrystalline than with nano- or microcrystalline silicon-germanium. The alloy ratio of the polycrystalline layer correspondes to the chemical composition of the amorphous starting layer. The polycrystalline silicon-germanium layers possess in the range of the interband transitions a reflection spectrum, as it is otherwise only known from monocrystalline reference layers. The improvement of the absorption in the photovoltaically relevant spectral range aimed by the application of silicon-germanium could be also proved by absorption measurments. Strongly correlated with the structural properties of the polycrystalline layers and the electronic band structure resulting from this are beside the optical properties also the electrical properties of the material, especially the charge-carrier mobility and the doping concentration. For binary silicon-germanium layers the hole concentration of about 2 x 10{sup 18} cm{sup -3} for pure silicon increrases to about 5 x 10{sup 20} cm{sub -3} for pure germanium. Temperature-resolved measurements were applied in order to detect doping levels respectively semiconductor-metal transitions. In the last part of the thesis the hydrogen passivation of polycrystalline thin silicon-germanium layers, which were fabricated by means of aluminium-induced layer exchange, is treated.

  1. Rare earth substitutional impurities in germanium: A hybrid density functional theory study

    Science.gov (United States)

    Igumbor, E.; Omotoso, E.; Tunhuma, S. M.; Danga, H. T.; Meyer, W. E.

    2017-10-01

    The Heyd, Scuseria, and Ernzerhof (HSE06) hybrid functional by means of density functional theory has been used to model the electronic and structural properties of rare earth (RE) substitutional impurities in germanium (REGe) . The formation and charge state transition energies for the REGe (RE = Ce, Pr, Er and Eu) were calculated. The energy of formation for the neutral charge state of the REGe lies between -0.14 and 3.13 eV. The formation energy result shows that the Pr dopant in Ge (PrGe) has the lowest formation energy of -0.14 eV, and is most energetically favourable under equilibrium conditions. The REGe induced charge state transition levels within the band gap of Ge. Shallow acceptor levels were induced by both the Eu (EuGe) and Pr (PrGe) dopants in Ge. The CeGe and ErGe exhibited properties of negative-U ordering with effective-U values of -0.85 and -1.07 eV, respectively.

  2. Effects of flame conditions on the synthesis of germanium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ifeacho, P.; Simanzhenkhov, V.; Wiggers, H.; Roth, P.; Schulz, C. [Duisburg-Essen Univ., Duisburg (Germany). Inst. fuer Verbrennung und Gasdynamik

    2005-07-01

    A low pressure premixed H{sub 2}/O{sub 2}/Ar flat flame doped with tetramethyl germanium Ge(CH{sub 3}){sub 4} (TMG) was used to investigate the influence of the variation of experimental parameters on GeO/GeO{sub 2} nanoparticle formation. GeO as well as GeO{sub 2} are thermodynamically stable, and their appearance and is appearance respectively provides valuable information on oxidizing and reducing conditions in the flame. The reactor was fed with different concentrations of TMG and operated for H{sub 2}/O{sub 2} ratios between 0.6 - 1.3. The pressure was varied between 25 - 55 mbar, while the gas velocity was varied between 0.69 - 1.95 m/s. It was found that, increasing pressure results in a reduction in mean particle diameter. An increase in oxygen concentration accelerates particle growth. For H{sub 2}/O{sub 2} < 1.0, the color of the GeO{sub x}, powders is while indicating the preferential formation of GeO{sub 2}. If the oxygen concentration decreases, the stoichiometry shifts towards GeO represented by a color transformation starting from while over grey to black. Transmission electron microscopy (TEM) and particle mass spectrometry (PMS) indicate the formation of particles with spherical morphology and mean diameters of 1.5 nm - 10 nm. (orig.)

  3. Effects of Ge-132 and GeO2 on seed germination and seedling growth of Oenothera biennis L. under NaCl stress.

    Science.gov (United States)

    Liu, Yan; Hou, Long-Yu; Li, Qing-Mei; Jiang, Ze-Ping; Gao, Wei-Dong; Zhu, Yan; Zhang, Hai-Bo

    2017-01-01

    To investigate the effects of β-carboxyethyl germanium sequioxide (Ge-132) and germanium dioxide (GeO 2 ) on improving salt tolerance of evening primrose (Oenothera biennis L.), seed germination, seedling growth, antioxidase and malondialdehyde (MDA) were observed under treatments of various concentrations (0, 5, 10, 20, 30 μM) of Ge in normal condition and in 50 mM NaCl solution. The results showed that both Ge-132 and GeO 2 treatments significantly increased seed germination percentage and shoot length in dose-dependent concentrations but inhibited early root elongation growth. 5-30 μM Ge-132 and 10, 20 μM GeO 2 treatments could significantly mitigate even eliminate harmful influence of salt, representing increased percentage of seed germination, root length, ratio between length of root and shoot, and decreased shoot length. These treatments also significantly decreased peroxidase (POD) and catalase (CAT) activities and MDA content. The mechanism is likely that Ge scavenges reactive oxygen species - especially hydrogen peroxide (H 2 O 2 ) - by its electron configuration 4S 2 4P 2 so as to reduce lipid peroxidation. This is the first report about the comparison of bioactivity effect of Ge-132 and GeO 2 on seed germination and seedling growth under salt stress. We conclude that Ge-132 is better than GeO 2 on promoting salt tolerance of seed and seedling.

  4. Pulse shape analysis of enriched BEGe detectors in vacuum cryostat and liquid argon

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Victoria [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Collaboration: GERDA-Collaboration

    2013-07-01

    The Gerda experiment searches for the lepton number violating neutrinoless double beta (0νββ) decay of {sup 76}Ge. Germanium diodes of BEGe type (Canberra, Belgium) made from isotopically modified material have been procured for Phase II of Gerda. They will improve the sensitivity of the experiment by additional target mass, improved energy resolution and enhanced pulse shape discrimination (PSD) against background events. The PSD efficiencies of the new enriched BEGe detectors were studied in vacuum cryostats as part of the characterization campaign at the HADES underground laboratory. For a deeper understanding of the pulse shape performance of the enriched BEGe detectors, detailed {sup 241}Am surface scans were performed. Unexpectedly high position-dependence of the pulse shape parameter Amplitude-over-Energy was found for some of the detectors. With further investigation this effect was traced to surface charge effects specific to the operational configuration of the detectors inside the vacuum cryostats. The standard behavior is restored when they are operated in liquid argon in the configuration intended for Gerda Phase II. Finally, five of the enriched BEGe diodes were installed in the Gerda liquid argon cryostat prior to the full upgrade. They show a good performance and are able to reject efficiently multi-site-events as well as β- and α-particles.

  5. The Majorana experiment. A straightforward neutrino mass experiment using the double-beta decay of 76Ge

    International Nuclear Information System (INIS)

    Miley, H.S.

    2004-01-01

    The Majorana Experiment proposes to measure the effective mass of the electron neutrino to as low as 0.02 eV using well-tested technology. A half-life of about 4E27 y, corresponding to a mass range of [0.02 - 0.07] eV can be reached by operating 500 kg of germanium enriched to 86% in 76 Ge deep underground. Radiological backgrounds of cosmogenic or primordial origin will be greatly reduced by ultra-low-background screening of detector, structural, and shielding materials, by chemical processing of materials, and by electronic rejection of multi-site events in the detector. Electronic background reduction is achieved with pulse-shape analysis, detector segmentation, and detector-to-detector coincidence rejection. Sensitivity calculations assuming worst-case germanium cosmogenic activation predict rapid growth in mass sensitivity (T1/2 at 90%CL) after the beginning of detector production: [0.08-0.28] eV at ∼1 year, [0.04-0.14] eV at ∼2.5 years, [0.03-0.10] eV at ∼5 years, and [0.02-0.07] eV at ∼10 years. The impact of primordial backgrounds in structural and electronic components is being studied at the 1 μBq/kg level, and appears to be controllable to below levels needed to attain these results. (author)

  6. The Majorana project: sup 7 sup 6 Ge 0 nu beta beta-decay neutrino mass measurement

    CERN Document Server

    Aalseth, C E

    2002-01-01

    Interest in, and the relevance of, next-generation 0 nu beta beta-decay experiments is increasing. Even with nonzero neutrino mass strongly suggested by SNO, Super Kamiokande, and similar experiments sensitive to delta m sup 2 , 0 nu beta beta-decay experiments are still the only way to establish the Dirac or Majorana nature of neutrinos by measuring effective electron neutrino mass, . Various theorists have recently argued in favor of a neutrino mass between 0.01 and 1 eV. The Majorana Project aims to probe this effective neutrino mass range, reaching a sensitivity of 0.02-0.07 eV. The experiment relies entirely on proven technology and has been devised based upon the materials, technology, and data analysis demonstrated to produce the lowest background per kilogram of fiducial germanium. The project plan includes 500 kg of germanium detector material enriched to 85% in sup 7 sup 6 Ge, specialized pulse-acquisition electronics and detector segmentation for background rejection, and underground electroformed ...

  7. The Majorana Experiment:. a Straightforward Neutrino Mass Experiment Using the Double-Beta Decay of 76GE

    Science.gov (United States)

    Miley, H. S.

    2004-04-01

    The Majorana Experiment proposes to measure the effective mass of the electron neutrino to as low as 0.02 eV using well-tested technology. A half-life of about 4E27 y, corresponding to a mass range of [0.02 - 0.07] eV can be reached by operating 500 kg of germanium enriched to 86% in 76Ge deep underground. Radiological backgrounds of cosmogenic or primordial origin will be greatly reduced by ultra-low-background screening of detector, structural, and shielding materials, by chemical processing of materials, and by electronic rejection of multi-site events in the detector. Electronic background reduction is achieved with pulse-shape analysis, detector segmentation, and detector-to-detector coincidence rejection. Sensitivity calculations assuming worst-case germanium cosmogenic activation predict rapid growth in mass sensitivity (T1/2 at 90%CL) after the beginning of detector production: [0.08-0.28] eV at ~1 year, [0.04-0.14] eV at ~2.5 years, [0.03-0.10] eV at ~5 years, and [0.02 - 0.07] eV at ~10 years. The impact of primordial backgrounds in structural and electronic components is being studied at the 1 μBq/kg level, and appears to be controllable to below levels needed to attain these results.

  8. Ion-beam mixing in silicon and germanium at low temperatures

    International Nuclear Information System (INIS)

    Clark, G.J.; Marwick, A.D.; Poker, D.B.

    1982-01-01

    Ion-beam mixing of thin marker layers in amorphous silicon and germanium was studied using irradiations with Xe ions at temperatures of 34k and 77k. The marker species, ion energies and doses were: in silicon, markers of Ge and Pt irradiated with 200-keV Xe up to 2.7x10 16 ions cm -2 ; and in germanium, markers of Al and Si bombarded with 295-keV Xe up to 1.63x10 16 ions cm -2 . In silicon, Pt markers were found to broaden at about the same rate at 34k and 77k; and the rate of broadening was similar to that found by other workers when expressed as an efficiency of mixing, i.e., when dependence on ion dose and deposited energy was factored out. However, a Ge marker irradiated at 34k did not broaden from its original thickness. In germanium, markers of both Al and Si were mixed by irradiation at 34k, but at 77k only the Al marker broadened; the Si marker did not. The broadening of the markers is ascribed to ballistic mixing, while the cases where no broadening occurred are explicable if diffusion by a defect mechanism transported displaced marker atoms back to traps near their original sites

  9. Fabrication of Hydrogenated Amorphous Germanium Thin Layer Film and ItsCharacterization

    International Nuclear Information System (INIS)

    Agus-Santoso; Lely-Susita RM; Tjipto-Sujitno

    2000-01-01

    Fabrication of hydrogenated amorphous Germanium thin film by vacuumevaporation method and then deposition with hydrogen atom by glow dischargeplasma radio frequency has been done. This germanium amorphous (a-Ge) thinfilm involves a lot of dangling bonds in the network due to the irregularityof the atomic structures and it will decrease is conductivity. To improve theband properties of (a-Ge) thin film layer a hydrogenated plasma isintroduced. Process of introducing of the hydrogen into the a-Ge film is meanto reduce the dangling bonds so that the best electric conductivity of a Ge:Hthin film will obtained. To identify the hydrogen atom in the sample acharacterization using infrared spectrometer has been done, as well as themeasurement of conductivity of the samples. From the characterization usinginfrared spectroscopy the existence of hydrogen atom was found at absorptionpeak with wave number 1637.5 cm -1 , while the optimum conductivity of thesample 1634.86 Ω -1 cm -1 was achieved at 343 o K. (author)

  10. Surface passivation of high-purity germanium gamma-ray detector

    International Nuclear Information System (INIS)

    Alexiev, D.; Butcher, K.S.A.; Edmondson, M.; Lawson, E.M.

    1993-01-01

    The experimental work consists of two parts. The first involves fabrication of hyper-pure germanium gamma ray detectors using standard surface treatment, chemical etchings and containment in a suitable cryostat. Then, after cooling the detectors to 77 K, γ-ray emissions from radioisotopes are resolved, resolution, depletion depth, V R versus I R characteristics and /N A -N D / of the germanium are measured. The second part of the work involves investigation of surface states in an effort to achieve long-term stability of operating characteristics. Several methods are used: plasma hydrogenation, a-Si and a-Ge pinch-off effect and simple oxidation. A-Ge and a-Si thicknesses were measured using Rutherford backscattering techniques; surface states were measured with deep level transient spectroscopy and diode reverse current versus reverse voltage plots. Some scanning electron microscope measurements were used in determining major film contaminants during backscattering of a-Si and a-Ge films. Surface passivation studies revealed unexpected hole trapping defects generated when a-Ge:H film is applied. The a-Si:H films were found to be mechanically strong, no defect traps were found and preliminary results suggest that such films will be good passivants. 14 refs., 2 tabs., 7 figs., 13 ills

  11. Thermoluminescence study of aluminium oxide doped germanium prepared by combustion synthesis method

    Directory of Open Access Journals (Sweden)

    Saharin Nurul Syazlin Binti

    2017-01-01

    Full Text Available The present paper reports the optimum concentration of germanium (Ge dopant in aluminium oxide (AhO3 samples prepared by combustion synthesis (CS method for thermoluminescence (TL studies. The samples were prepared at various Ge concentration i.e. 1 to 5% mol. The phase formation of un-doped and Ge-doped Al2O3 samples was determined using X-ray Diffraction (XRD. The sharp peaks present in the XRD pattern confirms the crystallinity of the samples. The samples were then exposed to 50 Gy Cobalt-60 sources (Gamma cell 220. TL glow curves were measured and recorded using a Harshaw Model 3500 TLD reader. Comparison of TL peaks were observed to obtain the best composition of Ge dopants. A simple glow curves TL peak at around 175̊C for all composition samples was observed. It was also found that the composition of aluminium oxide doped with 3.0% of germanium exhibits the highest thermoluminescence (TL intensity which is 349747.04 (a.u.

  12. Engineering the electronic band structures of novel cubic structured germanium monochalcogenides for thermoelectric applications

    Science.gov (United States)

    Ul Haq, Bakhtiar; AlFaify, S.; Ahmed, R.; Butt, Faheem K.; Laref, A.; Goumri-Said, Souraya; Tahir, S. A.

    2018-05-01

    Germanium mono-chalcogenides have received considerable attention for being a promising replacement for the relatively toxic and expensive chalcogenides in renewable and sustainable energy applications. In this paper, we explore the potential of the recently discovered novel cubic structured (π-phase) GeS and GeSe for thermoelectric applications in the framework of density functional theory coupled with Boltzmann transport theory. To examine the modifications in their physical properties, the across composition alloying of π-GeS and π-GeSe (such as π-GeS1-xSex for x =0, 0.25, 0.50, 0.75, and 1) has been performed that has shown important effects on the electronic band structures and effective masses of charge carriers. An increase in Se composition in π-GeS1-xSex has induced a downward shift in their conduction bands, resulting in the narrowing of their energy band gaps. The thermoelectric coefficients of π-GeS1-xSex have been accordingly influenced by the evolution of the electronic band structures and effective masses of charge carriers. π-GeS1-xSex features sufficiently larger values of Seebeck coefficients, power factors and figures of merit (ZTs), which experience further improvement with an increase in temperature, revealing their potential for high-temperature applications. The calculated results show that ZT values equivalent to unity can be achieved for π-GeS1-xSex at appropriate n-type doping levels. Our calculations for the formation enthalpies indicate that a π-GeS1-xSex alloying system is energetically stable and could be synthesized experimentally. These intriguing characteristics make π-GeS1-xSex a promising candidate for futuristic thermoelectric applications in energy harvesting devices.

  13. SiGe HBTs Optimization for Wireless Power Amplifier Applications

    Directory of Open Access Journals (Sweden)

    Pierre-Marie Mans

    2010-01-01

    Full Text Available This paper deals with SiGe HBTs optimization for power amplifier applications dedicated to wireless communications. In this work, we investigate the fT-BVCEO tradeoff by various collector optimization schemes such as epilayer thickness and dopant concentration, and SIC and CAP characteristics. Furthermore, a new trapezoidal base Germanium (Ge profile is proposed. Thanks to this profile, precise control of Ge content at the metallurgical emitter-base junction is obtained. Gain stability is obtained for a wide range of temperatures through tuning the emitter-base junction Ge percent. Finally, a comprehensive investigation of Ge introduction into the collector (backside Ge profile is conducted in order to improve the fT values at high injection levels.

  14. A CoGeNT confirmation of the DAMA signal

    International Nuclear Information System (INIS)

    Foot, R.

    2010-01-01

    The CoGeNT Collaboration has recently reported a rising low energy spectrum in their ultra low noise Germanium detector. This is particularly interesting as the energy range probed by CoGeNT overlaps with the energy region in which DAMA has observed their annual modulation signal. We show that the mirror dark matter candidate can simultaneously explain both the DAMA annual modulation signal and the rising low energy spectrum observed by CoGeNT. This constitutes a model dependent confirmation of the DAMA signal and adds weight to the mirror dark matter paradigm.

  15. Development of high responsivity Ge:Ga photoconductors

    International Nuclear Information System (INIS)

    Haegel, N.M.; Hueschen, M.R.; Haller, E.E.

    1984-06-01

    Czochralski-grown gallium-doped germanium (Ge:Ga) single crystal samples with a compensation of 10 -4 have been modified by the indiffusion of Cu to produce photoconductors which provide NEPs comparable to current optimum Ge:Ga detectors, but exhibit responsivities a factor of 5 to 6 times higher when tested at a background photon flux of 10 8 photons/sec at lambda=93 μm. The introduction of Cu, a triple acceptor in Ge which acts as a neutral scattering center, reduces carrier mobility and extends the breakdown field significantly in this ultra-low compensation material

  16. Soft chemistry routes to GeS2 nanoparticles

    Science.gov (United States)

    Courthéoux, Laurence; Mathiaud, Romain; Ribes, Michel; Pradel, Annie

    2018-04-01

    Spherical GeS2 particles are prepared by a low temperature liquid route with TEOG as germanium precursor and either H2S or thioacetamide (TAA) as sulfur precursors. The size and agglomeration of the particles change depending upon the temperature and nature of the solvent. Most synthesis lead to preparing amorphous GeS2. When the reaction kinetic is slowed down by using TAA at 25 °C, the obtained GeS2 product presents a larger order in the range of few Å as proven by Raman spectroscopy, even though it is still an amorphous compound as suggested by X-Ray diffraction and TEM experiments.

  17. Interaction of slow neutrons with 74Ge single crystals

    International Nuclear Information System (INIS)

    Pshenichnyj, V.A.; Pak En Men; Vorobkalo, F.M.; Vertebnyj, V.P.

    1986-01-01

    The total cross section of monocrystal from germanium-74 isotope by the time-of-flight method in the 0.017-10 eV range is measured. At room temperatures the above monocrystal possesses the capability of separating from the white reactor spectrum intensive beams of thermal neutrons. It is shown that the 74 Ge monocrystal by its filtering properties approaches to the Si monocrystal. The observed cross sections for Si, Ge, 74 Ge monocrystals in the thermal region of neutron energy are indicated in the study

  18. The coarsening process of Ge precipitates in an Al-4 wt.% Ge alloy

    Energy Technology Data Exchange (ETDEWEB)

    Deaf, G.H

    2004-05-01

    In this paper the results of a quantitative transmission electron microscopy (TEM) investigation of the precipitation process of Ge in an Al-4 wt.% Ge alloy are described. Two crystallographic orientation relationships between the irregular germanium precipitate and aluminum matrix were found to be [1 0 0]{sub Ge} || [1 1 0]{sub Al} and [1 1 4]{sub Ge} || [1 0 0]{sub Al}. The irregular germanium precipitates formed on [0 0 1]{sub Al} habit planes. The origin of the irregular shape is due to the existence of a highly anisotropic interfacial energy as well as in an isotropic growth rate along <1 1 0>{sub A1} directions. Particles sizes were determined for variety of isothermal ageing times at 348, 423 and 523 K. The coarsening of the different morphologies of Ge precipitates was found to obey Ostwald ripening kinetics. The TEM results showed that the coarsening of irregular particles was due to the interfacial coalescence between these particles. Nine different morphologies have been distinguished in the form of (i) irregular particles, (ii) spheres, (iii) hexagonal plates, (iv) rods, (v) triangular plates, (vi) laths, (vii) small tetrahedra, (viii) rectangular plates, and (ix) Lamellae shape.

  19. Effects of Germanium Tetrabromide Addition to Zinc Tetraphenyl Porphyrin / Fullerene Bulk Heterojunction Solar Cells

    Directory of Open Access Journals (Sweden)

    Atsushi Suzuki

    2014-03-01

    Full Text Available The effects of germanium tetrabromide addition to tetraphenyl porphyrin zinc (Zn-TPP/fullerene (C60 bulk heterojunction solar cells were characterized. The light-induced charge separation and charge transfer were investigated by current density and optical absorption. Addition of germanium tetrabromide inserted into active layer of Zn-TPP/C60 as bulk heterojunction had a positive effect on the photovoltaic and optical properties. The photovoltaic mechanism of the solar cells was discussed by experimental results. The photovoltaic performance was due to light-induced exciton promoted by insert of GeBr4 and charge transfer from HOMO of Zn-TPP to LUMO of C60 in the active layer.

  20. Current experiments in germanium 0 ν β β search -- GERDA and MAJORANA

    Science.gov (United States)

    von Sturm, K.

    2015-01-01

    There are unanswered questions regarding neutrino physics that are of great interest for the scientific community. For example the absolute masses, the mass hierarchy and the nature of neutrinos are unknown up to now. The discovery of neutrinoless double beta decay (0νββ) would prove the existence of a Majorana mass, which would be linked to the half-life of the decay, and would in addition provide an elegant solution for the small mass of the neutrinos via the seesaw mechanism. Because of an existing discovery claim of 0νββ of 76Ge and the excellent energy resolution achievable, germanium is of special interest in the search for 0νββ . In this article the state of the art of germanium 0νββ search, namely the GERDA experiment and MAJORANA demonstrator, is presented. In particular, recent results of the GERDA collaboration, which strongly disfavour the above mentioned claim, are discussed.

  1. Current experiments in germanium 0νββ search — GERDA and MAJORANA

    International Nuclear Information System (INIS)

    Von Sturm, K.

    2015-01-01

    There are unanswered questions regarding neutrino physics that are of great interest for the scientific community. For example the absolute masses, the mass hierarchy and the nature of neutrinos are unknown up to now. The discovery of neutrinoless double beta decay (0νββ) would prove the existence of a Majorana mass, which would be linked to the half-life of the decay, and would in addition provide an elegant solution for the small mass of the neutrinos via the seesaw mechanism. Because of an existing discovery claim of 0νββ of 76 Ge and the excellent energy resolution achievable, germanium is of special interest in the search for 0νββ. In this article the state of the art of germanium 0νββ search, namely the Gerda experiment and Majorana demonstrator, is presented. In particular, recent results of the Gerda collaboration, which strongly disfavour the above mentioned claim, are discussed.

  2. Post-growth annealing of germanium-tin alloys using pulsed excimer laser

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lanxiang; Wang, Wei; Zhou, Qian; Yeo, Yee-Chia, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117582 (Singapore); Pan, Jisheng; Zhang, Zheng [Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Singapore 117602 (Singapore); Tok, Eng Soon [Department of Physics, National University of Singapore, Singapore 117551 (Singapore)

    2015-07-14

    We investigate the impact of pulsed excimer laser anneal on fully strained germanium-tin alloys (Ge{sub 1−x}Sn{sub x}) epitaxially grown on Ge substrate by molecular beam epitaxy. Using atomic force microscopy, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy, the morphological and compositional evolution of Ge{sub 1−x}Sn{sub x} with Sn content up to 17% after annealing using various conditions is studied. Ge{sub 0.83}Sn{sub 0.17} samples annealed at 80 mJ/cm{sup 2} or 150 mJ/cm{sup 2} have no observable changes with respect to the as-grown sample. However, Ge{sub 0.83}Sn{sub 0.17} samples annealed at 250 mJ/cm{sup 2} or 300 mJ/cm{sup 2} have Sn-rich islands on the surface, which is due to Sn segregation in the compressively strained epitaxial film. For Ge{sub 0.89}Sn{sub 0.11}, significant Sn redistribution occurs only when annealed at 300 mJ/cm{sup 2}, indicating that it has better thermal stability than Ge{sub 0.83}Sn{sub 0.17}. A mechanism is proposed to explain the formation of Sn-rich islands and Sn-depleted regions.

  3. Structural and compositional evolution of carbon-doped Ge{sub 2}Sb{sub 2}Te{sub 5} film under different annealing conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki-Hong; Kyoung, Yong-Koo; Yun, Dong-Jin [AS group, CAS center, SAIT, Samsung Electronics Co. Ltd., Yongin 446-712 (Korea, Republic of); Choi, Sang-Jun, E-mail: sangjun5545.choi@samsung.com [Device Architecture Lab, Semiconductor R and D center, Samsung Electronics Co. Ltd., Yongin 446-712 (Korea, Republic of)

    2013-12-02

    Changes in the microstructural and electrical properties of carbon-doped Ge{sub 2}Sb{sub 2}Te{sub 5} during thermal annealing under N{sub 2} and air atmospheres are investigated. The occurrence of compositional and structural changes was found to depend on the annealing conditions, and in particular, on the out-diffusion of germanium atoms. The thick oxidation layer generated during air annealing prevented germanium out-diffusion, leading to structural changes but no compositional changes. In contrast, germanium out-diffusion occurred during annealing under N{sub 2}, leading to compositional changes but preventing structural changes. - Highlights: • We investigate the stability of 10% carbon-doped Ge2Sb2Te5 alloys. • The compositional and structural changes depend on the annealing conditions. • Germanium out-diffusion occurs during N2 annealing, leading to compositional changes. • The oxidation layer generated during air annealing prevents germanium out-diffusion.

  4. 2νββ decay of 76Ge into excited states with GERDA phase I

    Science.gov (United States)

    GERDA Collaboration; Agostini, M.; Allardt, M.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Barros, N.; Baudis, L.; Bauer, C.; Becerici-Schmidt, N.; Bellotti, E.; Belogurov, S.; Belyaev, S. T.; Benato, G.; Bettini, A.; Bezrukov, L.; Bode, T.; Borowicz, D.; Brudanin, V.; Brugnera, R.; Budjáš, D.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; D'Andrea, V.; Demidova, E. V.; di Vacri, A.; Domula, A.; Doroshkevich, E.; Egorov, V.; Falkenstein, R.; Fedorova, O.; Freund, K.; Frodyma, N.; Gangapshev, A.; Garfagnini, A.; Gooch, C.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Hegai, A.; Heisel, M.; Hemmer, S.; Heusser, G.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Janicskó Csáthy, J.; Jochum, J.; Junker, M.; Kazalov, V.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Klimenko, A.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lebedev, V. I.; Lehnert, B.; Liao, H. Y.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Majorovits, B.; Maneschg, W.; Medinaceli, E.; Mi, Y.; Misiaszek, M.; Moseev, P.; Nemchenok, I.; Palioselitis, D.; Panas, K.; Pandola, L.; Pelczar, K.; Pullia, A.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salathe, M.; Schmitt, C.; Schneider, B.; Schreiner, J.; Schulz, O.; Schwingenheuer, B.; Schönert, S.; Schütz, A.-K.; Selivanenko, O.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Stepaniuk, M.; Ur, C. A.; Vanhoefer, L.; Vasenko, A. A.; Veresnikova, A.; von Sturm, K.; Wagner, V.; Walter, M.; Wegmann, A.; Wester, T.; Wilsenach, H.; Wojcik, M.; Yanovich, E.; Zavarise, P.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zuber, K.; Zuzel, G.

    2015-11-01

    Two neutrino double beta decay of {}76{Ge} to excited states of {}76{Se} has been studied using data from Phase I of the GERDA experiment. An array composed of up to 14 germanium detectors including detectors that have been isotopically enriched in {}76{Ge} was deployed in liquid argon. The analysis of various possible transitions to excited final states is based on coincidence events between pairs of detectors where a de-excitation γ ray is detected in one detector and the two electrons in the other. No signal has been observed and an event counting profile likelihood analysis has been used to determine Frequentist 90% C.L. bounds for three transitions: {0}{{g}.{{s}}.}+-{2}1+: {T}1/22ν \\gt 1.6× {10}23 yr, {0}{{g}.{{s}}.}+-{0}1+: {T}1/22ν \\gt 3.7× {10}23 yr and {0}{{g}.{{s}}.}+-{2}2+: {T}1/22ν \\gt 2.3× {10}23 yr. These bounds are more than two orders of magnitude larger than those reported previously. Bayesian 90% credibility bounds were extracted and used to exclude several models for the {0}{{g}.{{s}}.}+-{0}1+ transition.

  5. Fabrication of Ge nanocrystals doped silica-on-silicon waveguides and observation of their strong quantum confinement effect

    DEFF Research Database (Denmark)

    Ou, Haiyan; Rottwitt, Karsten

    2009-01-01

    Germanium (Ge) nanocrystals embedded in silica matrix is an interesting material for new optoelectronic devices. In this paper, standard silica-on-silicon waveguides with a core doped by Ge nanocrystals were fabricated using plasma enhanced chemical vapour deposition and reactive ion etching...

  6. Ge nanocrystals formed by furnace annealing of Ge(x)[SiO2](1-x) films: structure and optical properties

    Science.gov (United States)

    Volodin, V. A.; Cherkov, A. G.; Antonenko, A. Kh; Stoffel, M.; Rinnert, H.; Vergnat, M.

    2017-07-01

    Ge(x)[SiO2](1-x) (0.1  ⩽  x  ⩽  0.4) films were deposited onto Si(0 0 1) or fused quartz substrates using co-evaporation of both Ge and SiO2 in high vacuum. Germanium nanocrystals were synthesized in the SiO2 matrix by furnace annealing of Ge x [SiO2](1-x) films with x  ⩾  0.2. According to electron microscopy and Raman spectroscopy data, the average size of the nanocrystals depends weakly on the annealing temperature (700, 800, or 900 °C) and on the Ge concentration in the films. Neither amorphous Ge clusters nor Ge nanocrystals were observed in as-deposited and annealed Ge0.1[SiO2]0.9 films. Infrared absorption spectroscopy measurements show that the studied films do not contain a noticeable amount of GeO x clusters. After annealing at 900 °C intermixing of germanium and silicon atoms was still negligible thus preventing the formation of GeSi nanocrystals. For annealed samples, we report the observation of infrared photoluminescence at low temperatures, which can be explained by exciton recombination in Ge nanocrystals. Moreover, we report strong photoluminescence in the visible range at room temperature, which is certainly due to Ge-related defect-induced radiative transitions.

  7. Rate of germanium-isotope production by background processes in the SAGE experiment

    International Nuclear Information System (INIS)

    Gavrin, V.N.; Gorbachev, V.V.; Ibragimova, T.V.; Cleveland, B.T.

    2002-01-01

    Data on a direct determination of systematic uncertainties caused by the background production of germanium isotopes in the radiochemical SAGE experiment measuring the solar-neutrino flux are analyzed. The result obtained for the rate of 68 Ge production is 6.5(1±1.0) times greater than the expected one; the rate of 69 Ge production does not exceed preliminary estimates. The above result for 68 Ge corresponds to the systematic uncertainty that is caused by the interaction of cosmic-ray muons and which is equal to 5.8% (4.5 SNU) at a solar-neutrino-capture rate of 77.0 SNU. An experiment is proposed that would test the effect of cosmic-ray muon influence on the SAGE systematic uncertainty and which would be performed at the location of the underground scintillation telescope facilities of the Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences)

  8. The germanium isotopes production rate in background process in SAGE experiment

    International Nuclear Information System (INIS)

    Gavrin, V.N.; Gorbachev, V.V.; Ibragimova, T.V.; Cleveland, B.T.

    2002-01-01

    The analysis of the direct determination of systematics connected with the germanium isotopes generation of in background processes in radiochemical SAGE experiments on measuring solar neutrinos is described. The found 68 Ge generation rate is 6.5 (1 ± 1.0) times higher than expected; the generation rate of 69 Ge does not exceed preliminary evaluations. The result on 68 Ge corresponds to the systematic of cosmic ray muons of 5.8% (4.5 SNU) for the measured capture rate of solar neutrino of 77.0 SNU. To check the cosmic-ray muon influence of the SAGE systematic one suggests the experiment in place of underground scintillation telescope of the Baksan neutrino observatory on the Institute for Nuclear Research of the RAS [ru

  9. Method of beryllium implantation in germanium substrate

    International Nuclear Information System (INIS)

    Kagawa, S.; Baba, Y.; Kaneda, T.; Shirai, T.

    1983-01-01

    A semiconductor device is disclosed, as well as a method for manufacturing it in which ions of beryllium are implanted into a germanium substrate to form a layer containing p-type impurity material. There after the substrate is heated at a temperature in the range of 400 0 C. to 700 0 C. to diffuse the beryllium ions into the substrate so that the concentration of beryllium at the surface of the impurity layer is in the order of 10 17 cm- 3 or more. In one embodiment, a p-type channel stopper is formed locally in a p-type germanium substrate and an n-type active layer is formed in a region surrounded by, and isolated from, the channel stopper region. In another embodiment, a relatively shallow p-type active layer is formed at one part of an n-type germanium substrate and p-type guard ring regions are formed surrounding, and partly overlapping said p-type active layer. In a further embodiment, a p-type island region is formed at one part of an n-type germanium substrate, and an n-type region is formed within said p-type region. In these embodiments, the p-type channel stopper region, p-type guard ring regions and the p-type island region are all formed by implanting ions of beryllium into the germanium substrate

  10. Temperature-dependent dielectric function of germanium in the UV–vis spectral range: A first-principles study

    International Nuclear Information System (INIS)

    Yang, J.Y.; Liu, L.H.; Tan, J.Y.

    2014-01-01

    The study of temperature dependence of thermophysical parameter dielectric function is key to understanding thermal radiative transfer in high-temperature environments. Limited by self-radiation and thermal oxidation, however, it is difficult to directly measure the high-temperature dielectric function of solids with present experimental technologies. In this work, we implement two first-principles methods, the ab initio molecular dynamics (AIMD) and density functional perturbation theory (DFPT), to study the temperature dependence of dielectric function of germanium (Ge) in the UV–vis spectral range in order to provide data of high-temperature dielectric function for radiative transfer study in high-temperature environments. Both the two methods successfully predict the temperature dependence of dielectric function of Ge. Moreover, the good agreement between the calculated results of the AIMD approach and experimental data at 825 K enables us to predict the high-temperature dielectric function of Ge with the AIMD method in the UV–vis spectral range. - Highlights: • The temperature dependence of dielectric function of germanium (Ge) is investigated with two first-principles methods. • The temperature effect on dielectric function of Ge is discussed. • The high-temperature dielectric function of Ge is predicted

  11. High level active n+ doping of strained germanium through co-implantation and nanosecond pulsed laser melting

    Science.gov (United States)

    Pastor, David; Gandhi, Hemi H.; Monmeyran, Corentin P.; Akey, Austin J.; Milazzo, Ruggero; Cai, Yan; Napolitani, Enrico; Gwilliam, Russell M.; Crowe, Iain F.; Michel, Jurgen; Kimerling, L. C.; Agarwal, Anuradha; Mazur, Eric; Aziz, Michael J.

    2018-04-01

    Obtaining high level active n+ carrier concentrations in germanium (Ge) has been a significant challenge for further development of Ge devices. By ion implanting phosphorus (P) and fluorine (F) into Ge and restoring crystallinity using Nd:YAG nanosecond pulsed laser melting (PLM), we demonstrate 1020 cm-3 n+ carrier concentration in tensile-strained epitaxial germanium-on-silicon. Scanning electron microscopy shows that after laser treatment, samples implanted with P have an ablated surface, whereas P + F co-implanted samples have good crystallinity and a smooth surface topography. We characterize P and F concentration depth profiles using secondary ion mass spectrometry and spreading resistance profiling. The peak carrier concentration, 1020 cm-3 at 80 nm below the surface, coincides with the peak F concentration, illustrating the key role of F in increasing donor activation. Cross-sectional transmission electron microscopy of the co-implanted sample shows that the Ge epilayer region damaged during implantation is a single crystal after PLM. High-resolution X-ray diffraction and Raman spectroscopy measurements both indicate that the as-grown epitaxial layer strain is preserved after PLM. These results demonstrate that co-implantation and PLM can achieve the combination of n+ carrier concentration and strain in Ge epilayers necessary for next-generation, high-performance Ge-on-Si devices.

  12. Synthesis and evaluation of germanic organometallic compounds as precursors for chemical vapor deposition (CVD) and for obtaining nanoparticles of elemental germanium

    International Nuclear Information System (INIS)

    Ballestero Martinez, Ernesto

    2014-01-01

    The interest in the development of materials that have applications in areas such as electronics or biomarkers has affected the synthesis of new compounds based on germanium. This element has two states of common oxidation, +4 and +2, of them, the +2 oxidation state is the least studied and more reactive. Additionally, compounds of germanium (II) have similarities to carbenes in terms Lewis'acid base chemistry. The preparation of compounds of germanium (II) with ligands β-diketiminates has made possible the stabilization of new chemical functionalities and, simultaneously, it has provided interesting thermal properties to develop new methods of preparation of materials with novel properties. The preparation of amides germanium (II) L'Ge (NHPh) [1, L'= {HC (CMeN-2,4,6-Me 3 C 6 H 2 ) 2 } - ], L'Ge (4-NHPy) [2], L'Ge (2-NHPy) [3] and LGe(2-NHPy) [4, L = {HC (CMeN-2,6- i Pr 2 C 6 H 3 ) 2 ] - ] are presented, the chemical and structural composition was determined by using techniques such as nuclear magnetic resonance ( 1 H, 13 C), elemental analysis, melting point, infrared spectroscopy, X-ray diffraction of single crystal and thermogravimetric analysis (TGA). The TGA has demonstrated that 1-4 experience a thermal decomposition, therefore, these compounds could be considered as potential starting materials for the obtaining of germanium nitride (GeN x ). Certainly, the availability of coordinating nitrogen atoms in the chemical composition in 2-4 have been interesting given that it could act as ligands in reactions with transition metal complexes. Thus, relevant information to molecular level could be obtained for some reactions and interactions that have used similar link sites in surface chemistry, for example, the chemical functionalization of silicon and germanium substrate. Additionally, the synthesis and structural characterization of germanium chloride compound (II) L G eCl [5, L' = HC{(CMe) (N-2,6-Me 2 C 6 H 3 )} 2 - ] is reported

  13. Uranium enrichment. Enrichment processes

    International Nuclear Information System (INIS)

    Alexandre, M.; Quaegebeur, J.P.

    2009-01-01

    Despite the remarkable progresses made in the diversity and the efficiency of the different uranium enrichment processes, only two industrial processes remain today which satisfy all of enriched uranium needs: the gaseous diffusion and the centrifugation. This article describes both processes and some others still at the demonstration or at the laboratory stage of development: 1 - general considerations; 2 - gaseous diffusion: physical principles, implementation, utilisation in the world; 3 - centrifugation: principles, elementary separation factor, flows inside a centrifuge, modeling of separation efficiencies, mechanical design, types of industrial centrifuges, realisation of cascades, main characteristics of the centrifugation process; 4 - aerodynamic processes: vortex process, nozzle process; 5 - chemical exchange separation processes: Japanese ASAHI process, French CHEMEX process; 6 - laser-based processes: SILVA process, SILMO process; 7 - electromagnetic and ionic processes: mass spectrometer and calutron, ion cyclotron resonance, rotating plasmas; 8 - thermal diffusion; 9 - conclusion. (J.S.)

  14. Results on neutrinoless double beta decay of 76Ge from GERDA Phase I

    International Nuclear Information System (INIS)

    Palioselitis, Dimitrios

    2015-01-01

    The Germanium Detector Array (GERDA) experiment is searching for the neutrinoless double beta (0νββ) decay of 76 Ge by operating bare germanium diodes in liquid argon. GERDA is located at the Gran Sasso National Laboratory (LNGS) in Italy. During Phase I, a total exposure of 21.6 kg yrand a background index of 0.01 cts/(keVkg yr) were reached. No signal was observed and a lower limit of T 0ν 1/2 > 2.1 · 10 25 yr(90% C.L.) is derived for the half life of the 0νββ decay of 76 Ge. (paper)

  15. Results on neutrinoless double beta decay of 76Ge from GERDA Phase I

    Science.gov (United States)

    Palioselitis, Dimitrios; GERDA Collaboration

    2015-05-01

    The Germanium Detector Array (GERDA) experiment is searching for the neutrinoless double beta (0νββ) decay of 76Ge by operating bare germanium diodes in liquid argon. GERDA is located at the Gran Sasso National Laboratory (LNGS) in Italy. During Phase I, a total exposure of 21.6 kg yrand a background index of 0.01 cts/(keVkg yr) were reached. No signal was observed and a lower limit of T0ν1/2 > 2.1 · 1025 yr(90% C.L.) is derived for the half life of the 0νββ decay of 76Ge.

  16. Using of germanium detectors in nuclear experiments with photon beams

    International Nuclear Information System (INIS)

    Kapitonov, I.M.; Tutin, I.A.

    1995-01-01

    Full text: The study of atomic nuclei with real photons is very important source of the information about nuclear structure. In such experiments the basic electromagnetic interaction between the photon and the target nuclei is well known. Experiments with photon beams become especially valuable when outcoming particles are also photons. In these cases completely model-independent information on nuclear structure can be extracted. The use of semiconductor Ge-spectrometers with excellent resolution and large sensitive volumes for recording outcoming photons gives us such an additional important advantage as possibility to observe individual closely spaced levels of the final nuclei. In the report an experience of using Ge-detectors in two types of nuclear experiments is described. Both of them - nuclear resonance fluorescence (NRF) and nuclear photodisintegration - are carried out in beams of bremsstrahlung gamma radiation. The central element of the setup recording gamma quanta in these experiments is germanium detector. NRF is unique method for studying low-lying excited nuclear states. The spins of the states can be determined easily from the measured angular distributions of scattered photons. Model independent parity assignments in NRF can be achieved by measuring polarization observables. There are two experimental possibilities: the use of linearly polarized photons (off-axis bremsstrahlung) in the entrance channel and the measurement of the linear polarization of the scattered photons using Compton polarimeters. For both methods several germanium detectors (3-5) must be used simultaneously. Nowadays Compton polarimeter can also be done from single large Ge-crystal by segmenting the outer electrode. Advantages and drawbacks of the methods and background conditions are discussed and requirements to Ge-crystals are formulated. The importance of using a new generation of electron accelerators with continuous wave (cw) beams for NRF-measurements is stressed. The

  17. Neutron-transmutation-doped germanium bolometers

    International Nuclear Information System (INIS)

    Palaio, N.P.; Rodder, M.; Haller, E.E.; Kreysa, E.

    1983-02-01

    Six slices of ultra-pure germanium were irradiated with thermal neutron fluences between 7.5 x 10 16 and 1.88 x 10 18 cm - 2 . After thermal annealing the resistivity was measured down to low temperatures ( 0 exp(δ/T) in the hopping conduction regime. Also, several junction FETs were tested for noise performance at room temperature and in an insulating housing in a 4.2K cryostat. These FETs will be used as first stage amplifiers for neutron-transmutation-doped germanium bolometers

  18. Neutron-transmutation-doped germanium bolometers

    Science.gov (United States)

    Palaio, N. P.; Rodder, M.; Haller, E. E.; Kreysa, E.

    1983-01-01

    Six slices of ultra-pure germanium were irradiated with thermal neutron fluences between 7.5 x 10 to the 16th and 1.88 x 10 to the 18th per sq cm. After thermal annealing the resistivity was measured down to low temperatures (less than 4.2 K) and found to follow the relationship rho = rho sub 0 exp(Delta/T) in the hopping conduction regime. Also, several junction FETs were tested for noise performance at room temperature and in an insulating housing in a 4.2 K cryostat. These FETs will be used as first stage amplifiers for neutron-transmutation-doped germanium bolometers.

  19. Germanium-overcoated niobium Dayem bridges

    International Nuclear Information System (INIS)

    Holdeman, L.B.; Peters, P.N.

    1976-01-01

    Overcoating constriction microbridges with semiconducting germanium provides additional thermal conductivity at liquid-helium temperatures to reduce the effects of self-heating in these Josephson junctions. Microwave-induced steps were observed in the I-V characteristics of an overcoated Dayem bridge fabricated in a 15-nm-thick niobium film; at 4.2 K (T/sub c/-T=2.6 K), at least 20 steps could be counted. No steps were observed in the I-V characteristics of the bridge prior to overcoating. In addition, the germanium overcoat can protect against electrical disturbances at room temperature

  20. Reactivity of silicon and germanium doped CNTs toward aromatic sulfur compounds: A theoretical approach

    International Nuclear Information System (INIS)

    Galano, Annia; Francisco-Marquez, Misaela

    2008-01-01

    Adsorption processes of thiophene and benzothiophene on pristine carbon nanotubes (CNTs), and on CNTs doped with Si or Ge, have been modeled with Density Functional. This is the first study on the chemical reactivity of such doped tubes. The calculated data suggest that the presence of silicon or germanium atoms in CNTs increases their reactivity toward thiophene, and benzothiophene. The adsorption of these species on pristine CNTs seems very unlikely to occur, while the addition products involving doped CNTs were found to be very stable, with respect to the isolated reactants, in terms of Gibbs free energy. Several of these adsorption processes were found to be significantly exergonic (ΔG < 0) in non-polar liquid phase. The results reported in this work suggest that Si and Ge defects on CNTs increase their reactivity toward unsaturated species, and could make them useful in the removal processes of aromatic sulfur compounds from oil-hydrocarbons. However, according to our results, CNTs doped with Si atoms are expected to be more efficient as aromatic sulfur compounds scavengers than those doped with Ge. These results also suggest that the presence of silicon and germanium atoms in the CNTs structures enhances their reactivity toward nucleophilic molecules, compared to pristine carbon nanotubes

  1. Thermodynamic calculations of self- and hetero-diffusion parameters in germanium

    International Nuclear Information System (INIS)

    Saltas, V.; Vallianatos, F.

    2015-01-01

    In the present work, the diffusion coefficients of n- and p-type dopants (P, As, Sb, Al) and self-diffusion in crystalline germanium are calculated from the bulk elastic properties of the host material based on the cBΩ thermodynamic model. The calculated diffusion coefficients as a function of temperature and the activation enthalpies prove to be in full agreement with the reported experimental results. Additional point defect parameters such as activation entropy, activation volume and activation Gibbs free energy are also calculated for each diffusing element. The pressure dependence of self-diffusion coefficients in germanium is also verified at high temperatures (876 K–1086 K), in agreement with reported results ranging from ambient pressure up to 600 MPa and is further calculated at pressures up to 3 GPa, where the phase transition to Ge II occurs. - Highlights: • Calculation of diffusivities of n- and p-type dopants in Ge from elastic properties. • Calculation of point defect parameters according to the cBΩ thermodynamic model. • Prediction of the pressure dependence of self-diffusion coefficients in Ge

  2. Study of low dimensional SiGe island on Si for potential visible Metal-Semiconductor-Metal photodetector

    Science.gov (United States)

    Rahim, Alhan Farhanah Abd; Zainal Badri, Nur'Amirah; Radzali, Rosfariza; Mahmood, Ainorkhilah

    2017-11-01

    In this paper, an investigation of design and simulation of silicon germanium (SiGe) islands on silicon (Si) was presented for potential visible metal semiconductor metal (MSM) photodetector. The characterization of the performances in term of the structural, optical and electrical properties of the structures was analyzed from the simulation results. The project involves simulation using SILVACO Technology Computer Aided Design (TCAD) tools. The different structures of the silicon germanium (SiGe) island on silicon substrate were created, which were large SiGe, small SiGe, combination SiGe and bulk Ge. All the structures were tested for potential Metal Semiconductor Metal (MSM) photodetector. The extracted data such as current versus voltage characteristic, current gain and spectral response were obtained using ATLAS SILVACO tools. The performance of SiGe island structures and bulk Ge on Si substrate as (MSM) photodetector was evaluated by photo and dark current-voltage (I-V) characteristics. It was found that SiGe islands exhibited higher energy band gap compared to bulk Ge. The SiGe islands current-voltage characteristics showed improved current gain compared to bulk Ge. Specifically the enhancement of the islands gain was contributed by the enhanced photo currents and lower dark currents. The spectral responses of the SiGe islands showed peak response at 590 nm (yellow) which is at the visible wavelength. This shows the feasibility of the SiGe islands to be utilized for visible photodetections.

  3. Study of low dimensional SiGe island on Si for potential visible Metal-Semiconductor-Metal photodetector

    Directory of Open Access Journals (Sweden)

    Abd Rahim Alhan Farhanah

    2017-01-01

    Full Text Available In this paper, an investigation of design and simulation of silicon germanium (SiGe islands on silicon (Si was presented for potential visible metal semiconductor metal (MSM photodetector. The characterization of the performances in term of the structural, optical and electrical properties of the structures was analyzed from the simulation results. The project involves simulation using SILVACO Technology Computer Aided Design (TCAD tools. The different structures of the silicon germanium (SiGe island on silicon substrate were created, which were large SiGe, small SiGe, combination SiGe and bulk Ge. All the structures were tested for potential Metal Semiconductor Metal (MSM photodetector. The extracted data such as current versus voltage characteristic, current gain and spectral response were obtained using ATLAS SILVACO tools. The performance of SiGe island structures and bulk Ge on Si substrate as (MSM photodetector was evaluated by photo and dark current-voltage (I-V characteristics. It was found that SiGe islands exhibited higher energy band gap compared to bulk Ge. The SiGe islands current-voltage characteristics showed improved current gain compared to bulk Ge. Specifically the enhancement of the islands gain was contributed by the enhanced photo currents and lower dark currents. The spectral responses of the SiGe islands showed peak response at 590 nm (yellow which is at the visible wavelength. This shows the feasibility of the SiGe islands to be utilized for visible photodetections.

  4. Ultrafast palladium diffusion in germanium

    KAUST Repository

    Tahini, Hassan Ali

    2015-01-01

    The slow transport of dopants through crystal lattices has hindered the development of novel devices. Typically atoms are contained within deep potential energy wells which necessitates multiple attempts to hop between minimum energy positions. This is because the bonds that constrain atoms are strongest at the minimum positions. As they hop between sites the bonds must be broken, only to re-form as the atoms slide into adjacent minima. Here we demonstrate that the Pd atoms introduced into the Ge lattice behave differently. They retain bonds as the atoms shift across so that at the energy maximum between sites Pd still exhibits strong bonding characteristics. This reduces the energy maximum to almost nothing (a migration energy of only 0.03 eV) and means that the transport of Pd through the Ge lattice is ultrafast. We scrutinize the bonding characteristics at the atomic level using quantum mechanical simulation tools and demonstrate why Pd behaves so differently to other metals we investigated (i.e. Li, Cu, Ag, Pt and Au). Consequently, this fundamental understanding can be extended to systems where extremely rapid diffusion is desired, such as radiation sensors, batteries and solid oxide fuel cells.

  5. Germanium nanoparticles grown at different deposition times for memory device applications

    International Nuclear Information System (INIS)

    Mederos, M.; Mestanza, S.N.M.; Lang, R.; Doi, I.; Diniz, J.A.

    2016-01-01

    In the present work, circular Metal-Oxide-Semiconductor capacitors with 200 μm of diameter and germanium (Ge) nanoparticles (NPs) embedded in the gate oxide are studied for memory applications. Optimal process parameters are investigated for Ge NPs growing by low pressure chemical vapor deposition at different deposition times. Photoluminescence measurements showed room-temperature size-dependent green-red region bands attributed to quantum confinement effects present in the NPs. High-frequency capacitance versus voltage measurements demonstrated the memory effects on the MOS structures due to the presence of Ge NPs in the gate oxide acting as discrete floating gates. Current versus voltage measurements confirmed the Fowler-Nordheim tunneling as the programming mechanism of the devices. - Highlights: • Ge nanoparticles with high density and uniforms sizes were obtained by LPCVD. • Room-temperature size-dependent bands of photoluminescence were observed. • MOS capacitors with Ge nanoparticles embedded in the oxide were fabricated. • Ge nanoparticles are the main responsible for the memory properties in the devices. • Fowler-Nordheim tunneling is the conduction mechanism observed on the devices.

  6. Effect of interface roughness on the carrier transport in germanium MOSFETs investigated by Monte Carlo method

    International Nuclear Information System (INIS)

    Gang, Du; Xiao-Yan, Liu; Zhi-Liang, Xia; Jing-Feng, Yang; Ru-Qi, Han

    2010-01-01

    Interface roughness strongly influences the performance of germanium metal–organic–semiconductor field effect transistors (MOSFETs). In this paper, a 2D full-band Monte Carlo simulator is used to study the impact of interface roughness scattering on electron and hole transport properties in long- and short- channel Ge MOSFETs inversion layers. The carrier effective mobility in the channel of Ge MOSFETs and the in non-equilibrium transport properties are investigated. Results show that both electron and hole mobility are strongly influenced by interface roughness scattering. The output curves for 50 nm channel-length double gate n and p Ge MOSFET show that the drive currents of n- and p-Ge MOSFETs have significant improvement compared with that of Si n- and p-MOSFETs with smooth interface between channel and gate dielectric. The 82% and 96% drive current enhancement are obtained for the n- and p-MOSFETs with the completely smooth interface. However, the enhancement decreases sharply with the increase of interface roughness. With the very rough interface, the drive currents of Ge MOSFETs are even less than that of Si MOSFETs. Moreover, the significant velocity overshoot also has been found in Ge MOSFETs. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  7. Germanium nanoparticles grown at different deposition times for memory device applications

    Energy Technology Data Exchange (ETDEWEB)

    Mederos, M., E-mail: melissa.mederos@gmail.com [Center for Semiconductor Components and Nanotechnology (CCSNano), University of Campinas (Unicamp), Rua João Pandia Calógeras 90, Campinas, CEP: 13083-870, São Paulo (Brazil); Mestanza, S.N.M. [Federal University of ABC (UFABC), Rua Santa Adélia 166, Bangu, Santo André, CEP: 09210-170, São Paulo (Brazil); Lang, R. [Institute of Science and Technology, Federal University of São Paulo (UNIFESP), Rua Talim, 330, São José dos Campos, CEP: 12231-280, São Paulo (Brazil); Doi, I.; Diniz, J.A. [Center for Semiconductor Components and Nanotechnology (CCSNano), University of Campinas (Unicamp), Rua João Pandia Calógeras 90, Campinas, CEP: 13083-870, São Paulo (Brazil); School of Electrical and Computer Engineering, University of Campinas (Unicamp), Av. Albert Einstein 400, Campinas, CEP: 13083-852, São Paulo (Brazil)

    2016-07-29

    In the present work, circular Metal-Oxide-Semiconductor capacitors with 200 μm of diameter and germanium (Ge) nanoparticles (NPs) embedded in the gate oxide are studied for memory applications. Optimal process parameters are investigated for Ge NPs growing by low pressure chemical vapor deposition at different deposition times. Photoluminescence measurements showed room-temperature size-dependent green-red region bands attributed to quantum confinement effects present in the NPs. High-frequency capacitance versus voltage measurements demonstrated the memory effects on the MOS structures due to the presence of Ge NPs in the gate oxide acting as discrete floating gates. Current versus voltage measurements confirmed the Fowler-Nordheim tunneling as the programming mechanism of the devices. - Highlights: • Ge nanoparticles with high density and uniforms sizes were obtained by LPCVD. • Room-temperature size-dependent bands of photoluminescence were observed. • MOS capacitors with Ge nanoparticles embedded in the oxide were fabricated. • Ge nanoparticles are the main responsible for the memory properties in the devices. • Fowler-Nordheim tunneling is the conduction mechanism observed on the devices.

  8. Germanium Doping to Improve Carrier Mobility in CdO Films

    Directory of Open Access Journals (Sweden)

    A. A. Dakhel

    2013-01-01

    Full Text Available This investigation addresses the structural, optical, and electrical properties of germanium incorporated cadmium oxide (CdO : Ge thin films. The focus was on the improvement in carrier mobility to achieve high transparency for near-infrared light and low resistivity at the same time. The properties were studied using X-ray diffraction, SEM, spectral photometry, and Hall measurements. All CdO : Ge films were polycrystalline with high texture orientation along [111] direction. It was observed that it is possible to control the carrier concentration ( and mobility ( with Ge-incorporation level. The mobility could be improved to a highest value of  cm2/V·s with Ge doping of 0.25 wt% while maintaining the electrical resistivity as low as  Ω·cm and good transparency % in the NIR spectral region. The results of the present work proved to select Ge as dopant to achieve high carrier mobility with low resistivity for application in transparent conducting oxide (TCO field. Generally, the properties found make CdO : Ge films particularly interesting for the application in optoelectronic devices like thin-film solar cells.

  9. SO-limited mobility in a germanium inversion channel with non-ideal metal gate

    International Nuclear Information System (INIS)

    Shah, Raheel; De Souza, M.M.

    2008-01-01

    Germanium is an attractive candidate for ultra fast CMOS technology due to its potential for doubling electron mobility and quadrupling hole mobility in comparison to silicon. To maintain the requirements of the International Technology Roadmap for Semiconductors (ITRS), high-κ insulators and metal gates will be required in conjunction with Ge technology. Key issues which will have to be addressed in achieving Ge technology are: trap free insulators, assessment of appropriate crystallographic orientations and the selection of gate metals for the best mobility. In this work mobilities are evaluated for Ge-nMOSFET with two metal gates (Al and TiN) and high-κ (HfO 2 ) insulator. Scattering with bulk phonons, surface roughness and high-κ phonons are taken into account. It is predicted that Al as the gate material on Ge {100} substrate performs 50% better than Ge {111} orientation at a sheet concentration of 1 x 10 13 cm -2 . Surface roughness is likely to be the most damaging mobility degradation mechanism at high fields for Ge {111}

  10. Ordering of germanium islands in the Si1-xGex/Si system pre-structured by misfit dislocations

    DEFF Research Database (Denmark)

    Pedersen, Erik Vesterlund; Shiryaev, Sergey Y.; Jensen, Flemming

    1998-01-01

    to the ordering obtained with compositionally graded buffer layers is discussed. Finally, the relaxed uniform Si0.84Ge0.16 buffer layer structures are used ro investigate the kinetics of the ordering of the islands, either by changing the amount of deposited material or by changing the deposition temperature......We have investigated the ordering of germanium islands on a relaxed uniform Si0.84Ge0.16 buffer layer by atomic force microscopy and transmission electron microscopy. A pronounced ordering with the islands situated along dislocation slip band lines was observed. The resemblance of this ordering...

  11. Optical Activation of Germanium Plasmonic Antennas in the Mid-Infrared

    Science.gov (United States)

    Fischer, Marco P.; Schmidt, Christian; Sakat, Emilie; Stock, Johannes; Samarelli, Antonio; Frigerio, Jacopo; Ortolani, Michele; Paul, Douglas J.; Isella, Giovanni; Leitenstorfer, Alfred; Biagioni, Paolo; Brida, Daniele

    2016-07-01

    Impulsive interband excitation with femtosecond near-infrared pulses establishes a plasma response in intrinsic germanium structures fabricated on a silicon substrate. This direct approach activates the plasmonic resonance of the Ge structures and enables their use as optical antennas up to the mid-infrared spectral range. The optical switching lasts for hundreds of picoseconds until charge recombination redshifts the plasma frequency. The full behavior of the structures is modeled by the electrodynamic response established by an electron-hole plasma in a regular array of antennas.

  12. Determination of surface recombination velocity and bulk lifetime in detector grade silicon and germanium crystals

    International Nuclear Information System (INIS)

    Derhacobian, N.; Fine, P.; Walton, J.T.; Wong, Y.K.; Rossington, C.S.; Luke, P.N.

    1993-10-01

    Utility of a noncontact photoconductive decay (PCD) technique is demonstrated in measuring bulk lifetime, τ B , and surface recombination velocity, S, in detector grade silicon and germanium crystals. We show that the simple analytical equations which relate the observed effective lifetimes in PCD transients to τ B and S have a limited range of applicability. The noncontact PCD technique is used to determine the effect of several surface treatments on the observed effective lifetimes in Si and Ge. A degradation of the effective lifetime in Si is reported as result of the growth of a thin layer of native oxide at room temperature under atmospheric conditions

  13. Experimental Search for Solar Axions via Coherent Primakoff Conversion in a Germanium Spectrometer

    CERN Document Server

    Avignone, F T; Brodzinski, R; Collar, J I; Creswick, R J; Di Gregorio, D E; Farach, H A; Gattone, A O; Guérard, C K; Hasenbalg, F; Huck, H; Miley, H S; Morales, A; Morales, J; Nussinov, S; De Solorzano, A O; Reeves, J H; Villar, J; Zioutas, Konstantin

    1998-01-01

    Results are reported of an experimental search for the unique, rapidly varying temporal pattern of solar axions coherently converting into photons via the Primakoff effect in a single crystal germanium detector. This conversion is predicted when axions are incident at a Bragg angle with a crystalline plane. The analysis of approximately 1.94 kg.yr of data from the 1 kg DEMOS detector in Sierra Grande, Argentina, yields a new laboratory bound on axion-photon coupling of $g_{a\\gamma \\gamma} < 2.7\\cdot 10^{-9}$ GeV$^{-1}$, independent of axion mass up to ~ 1 keV.

  14. Simulation of core-level binding energy shifts in germanium-doped lead telluride crystals

    International Nuclear Information System (INIS)

    Zyubin, A.S.; Dedyulin, S.N.; Yashina, L.V.; Shtanov, V.I.

    2007-01-01

    To simulate the changes in core-level binding energies in germanium-doped lead telluride, cluster calculations of the changes in the electrostatic potential at the corresponding centers have been performed. Different locations of the Ge atom in the crystal bulk have been considered: near vacancies, near another dopant site, and near the surface. For calculating the potential in the clusters that model the bulk and the surface of the lead telluride crystal (c-PbTe), the electron density obtained in the framework of the Hartree-Fock and hybrid density functional theory (DFT) methods has been used [ru

  15. Band structure analysis in SiGe nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Amato, Michele [' Centro S3' , CNR-Istituto Nanoscienze, via Campi 213/A, 41100 Modena (Italy); Dipartimento di Scienze e Metodi dell' Ingegneria, Universita di Modena e Reggio Emilia, via Amendola 2 Pad. Morselli, I-42100 Reggio Emilia (Italy); Palummo, Maurizia [European Theoretical Spectroscopy Facility (ETSF) (Italy); CNR-INFM-SMC, Dipartimento di Fisica, Universita di Roma, ' Tor Vergata' , via della Ricerca Scientifica 1, 00133 Roma (Italy); Ossicini, Stefano, E-mail: stefano.ossicini@unimore.it [' Centro S3' , CNR-Istituto Nanoscienze, via Campi 213/A, 41100 Modena (Italy) and Dipartimento di Scienze e Metodi dell' Ingegneria, Universita di Modena e Reggio Emilia, via Amendola 2 Pad. Morselli, I-42100 Reggio Emilia (Italy) and European Theoretical Spectroscopy Facility - ETSF (Italy) and Centro Interdipartimentale ' En and Tech' , Universita di Modena e Reggio Emilia, via Amendola 2 Pad. Morselli, I-42100 Reggio Emilia (Italy)

    2012-06-05

    One of the main challenges for Silicon-Germanium nanowires (SiGe NWs) electronics is the possibility to modulate and engine their electronic properties in an easy way, in order to obtain a material with the desired electronic features. Diameter and composition constitute two crucial ways for the modification of the band gap and of the band structure of SiGe NWs. Within the framework of density functional theory we present results of ab initio calculations regarding the band structure dependence of SiGe NWs on diameter and composition. We point out the main differences with respect to the case of pure Si and Ge wires and we discuss the particular features of SiGe NWs that are useful for future technological applications.

  16. Band structure analysis in SiGe nanowires

    International Nuclear Information System (INIS)

    Amato, Michele; Palummo, Maurizia; Ossicini, Stefano

    2012-01-01

    One of the main challenges for Silicon-Germanium nanowires (SiGe NWs) electronics is the possibility to modulate and engine their electronic properties in an easy way, in order to obtain a material with the desired electronic features. Diameter and composition constitute two crucial ways for the modification of the band gap and of the band structure of SiGe NWs. Within the framework of density functional theory we present results of ab initio calculations regarding the band structure dependence of SiGe NWs on diameter and composition. We point out the main differences with respect to the case of pure Si and Ge wires and we discuss the particular features of SiGe NWs that are useful for future technological applications.

  17. Filtering microphonics in dark matter germanium experiments

    International Nuclear Information System (INIS)

    Morales, J.; Garcia, E.; Ortiz de Solorzano, A.; Morales, A.; Nunz-Lagos, R.; Puimedon, J.; Saenz, C.; Villar, J.A.

    1992-01-01

    A technique for reducing the microphonic noise in a germanium spectrometer used in dark matter particles searches is described. Filtered energy spectra, corresponding to 48.5 kg day of data in a running experiment in the Canfranc tunnel are presented. Improvements of this filtering procedure with respect to the method of rejecting those events not distributed evenly in time are also discussed. (orig.)

  18. Pulse shape analysis for the GERDA experiment to set a new limit on the half-life of 0νββ decay of {sup 76}Ge

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Victoria Elisabeth

    2017-01-25

    The GERDA experiment searches for neutrinoless double beta (0νββ) decay of {sup 76}Ge using high purity germanium (HPGe) detectors operated in liquid argon (LAr). The aim is to explore half-lives of the order of 10{sup 26} yr. Therefore, GERDA relies on improved active background reduction techniques such as pulse shape discrimination (PSD) in which the time structure of the germanium signals is analyzed to discriminate signal- from background-like events. Two types of HPGe detectors are operated: semi-coaxial detectors previously used in the Heidelberg-Moscow and IGEX experiments and new Broad Energy Germanium (BEGe) detectors which feature an improved energy resolution and enhanced PSD. In Phase I of the experiment, five enriched BEGe detectors were used for the first time in the search for 0νββ decay. A PSD based on a single parameter, the ratio of the maximum current amplitude over the energy A/E is applied. 83% of the background events in a 232 keV region around Q{sub ββ} are rejected with a high signal efficiency of (92.1 ± 1.9) %. The achieved background index (BI) is (5.4{sup +4.1}{sub -3.4}) . 10{sup -3} (counts)/(keV.kg.yr). This is an improvement by a factor of 10 compared to previous germanium based 0νββ experiments. Phase II of the experiment includes a major upgrade: for further background rejection, the LAr cryostat is instrumented to detect argon scintillation light. Additional 25 BEGe detectors are installed. After PSD and LAr veto a BI of (0.7{sup +1.3}{sub -0.5}) . 10{sup -3} (counts)/(keV.kg.yr) is achieved. This is the best BI achieved in 0νββ experiments so far. A frequentist statistical analysis is performed on the combined data collected in GERDA Phase I and the first Phase II release. A new limit on the half-life of 0νββ decay of {sup 76}Ge is set to T{sup 0ν}{sub 1/2}>5.3.10{sup 25} yr at 90% C.L., with a median sensitivity of T{sup 0ν}{sub 1/2}>4.0.10{sup 25} yr at 90% C.L.

  19. Electron Transport Properties of Ge nanowires

    Science.gov (United States)

    Hanrath, Tobias; Khondaker, Saiful I.; Yao, Zhen; Korgel, Brian A.

    2003-03-01

    Electron Transport Properties of Ge nanowires Tobias Hanrath*, Saiful I. Khondaker, Zhen Yao, Brian A. Korgel* *Dept. of Chemical Engineering, Dept. of Physics, Texas Materials Institute, and Center for Nano- and Molecular Science and Technology University of Texas at Austin, Austin, Texas 78712-1062 e-mail: korgel@mail.che.utexas.edu Germanium (Ge) nanowires with diameters ranging from 6 to 50 nm and several micrometer in length were grown via a supercritical fluid-liquid-solid synthesis. Parallel electron energy loss spectroscopy (PEELS) was employed to study the band structure and electron density in the Ge nanowires. The observed increase in plasmon peak energy and peak width with decreasing nanowire diameter is attributed to quantum confinement effects. For electrical characterization, Ge nanowires were deposited onto a patterned Si/SiO2 substrate. E-beam lithography was then used to form electrode contacts to individual nanowires. The influence of nanowire diameter, surface chemistry and crystallographic defects on electron transport properties were investigated and the comparison of Ge nanowire conductivity with respect to bulk, intrinsic Ge will be presented.

  20. Ge extraction from gasification fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Oriol Font; Xavier Querol; Angel Lopez-Soler; Jose M. Chimenos; Ana I. Fernandez; Silvia Burgos; Francisco Garcia Pena [Institute of Earth Sciences ' Jaume Almera' , Barcelona (Spain)

    2005-08-01

    Water-soluble germanium species (GeS{sub 2}, GeS and hexagonal-GeO{sub 2}) are generated during coal gasification and retained in fly ash. This fact together with the high market value of this element and the relatively high contents in the fly ashes of the Puertollano Integrated Gasification in Combined Cycle (IGCC) plant directed our research towards the development of an extraction process for this element. Major objectives of this research was to find a low cost and environmentally suitable process. Several water based extraction tests were carried out using different Puertollano IGCC fly ash samples, under different temperatures, water/fly ash ratios, and extraction times. High Ge extraction yields (up to 84%) were obtained at room temperature (25{sup o}C) but also high proportions of other trace elements (impurities) were simultaneously extracted. Increasing the extraction temperature to 50, 90 and 150{sup o}C, Ge extraction yields were kept at similar levels, while reducing the content of impurities, the water/fly ash ratio and extraction time. The experimental data point out the influence of chloride, calcium and sulphide dissolutions on the Ge extraction. 16 refs., 9 figs., 6 tabs.

  1. Fabrication of Ge-on-insulator wafers by Smart-CutTM with thermal management for undamaged donor Ge wafers

    Science.gov (United States)

    Kim, Munho; Cho, Sang June; Jayeshbhai Dave, Yash; Mi, Hongyi; Mikael, Solomon; Seo, Jung-Hun; Yoon, Jung U.; Ma, Zhenqiang

    2018-01-01

    Newly engineered substrates consisting of semiconductor-on-insulator are gaining much attention as starting materials for the subsequent transfer of semiconductor nanomembranes via selective etching of the insulating layer. Germanium-on-insulator (GeOI) substrates are critically important because of the versatile applications of Ge nanomembranes (Ge NMs) toward electronic and optoelectronic devices. Among various fabrication techniques, the Smart-CutTM technique is more attractive than other methods because a high temperature annealing process can be avoided. Another advantage of Smart-CutTM is the reusability of the donor Ge wafer. However, it is very difficult to realize an undamaged Ge wafer because there exists a large mismatch in the coefficient of thermal expansion among the layers. Although an undamaged donor Ge wafer is a prerequisite for its reuse, research related to this issue has not yet been reported. Here we report the fabrication of 4-inch GeOI substrates using the direct wafer bonding and Smart-CutTM process with a low thermal budget. In addition, a thermo-mechanical simulation of GeOI was performed by COMSOL to analyze induced thermal stress in each layer of GeOI. Crack-free donor Ge wafers were obtained by annealing at 250 °C for 10 h. Raman spectroscopy and x-ray diffraction (XRD) indicated similarly favorable crystalline quality of the Ge layer in GeOI compared to that of bulk Ge. In addition, Ge p-n diodes using transferred Ge NM indicate a clear rectifying behavior with an on and off current ratio of 500 at ±1 V. This demonstration offers great promise for high performance transferrable Ge NM-based device applications.

  2. Improving the electrode performance of Ge through Ge@C core-shell nanoparticles and graphene networks.

    Science.gov (United States)

    Xue, Ding-Jiang; Xin, Sen; Yan, Yang; Jiang, Ke-Cheng; Yin, Ya-Xia; Guo, Yu-Guo; Wan, Li-Jun

    2012-02-08

    Germanium is a promising high-capacity anode material for lithium ion batteries, but it usually exhibits poor cycling stability because of its huge volume variation during the lithium uptake and release process. A double protection strategy to improve the electrode performance of Ge through the use of Ge@C core-shell nanostructures and reduced graphene oxide (RGO) networks has been developed. The as-synthesized Ge@C/RGO nanocomposite showed excellent cycling performance and rate capability in comparison with Ge@C nanoparticles when used as an anode material for Li ion batteries, which can be attributed to the electronically conductive and elastic RGO networks in addition to the carbon shells and small particle sizes of Ge. The strategy is simple yet very effective, and because of its versatility, it may be extended to other high-capacity electrode materials with large volume variations and low electrical conductivities.

  3. Development of a production scale purification of Ge-68 from irradiated gallium metal

    Energy Technology Data Exchange (ETDEWEB)

    Fitzsimmons, Jonathan M.; Mausner, Leonard [Brookhaven National Laboratory, Upton, NY (United States)

    2015-05-01

    Germanium-68 (Ge-68) is produced by proton irradiation of a gallium metal target and purified by organic extraction. The Ge-68 can be used in a medical isotope generator to produce Gallium-68 (Ga-68) which can be used to radiolabel PET imaging agents. The emerging use of Ge-68 in the Ga-68 medical isotope generator has caused us to develop a new purification method for Ge-68 that does not use toxic solvents. The purpose of this work was to develop a production scale separation of Ge-68 that utilizes a leaching step to remove a bulk of the gallium metal, followed by purification with Sephadex {sup copyright} G25. Production scale (300 mCi) purification was performed with the new method. The purified Ge-68 contained the highest radioactivity concentration of Ge-68 produced at BNL; the sample meet Department of Energy specifications and the method had an excellent recovery of Ge-68.

  4. High temperature dielectric function of silicon, germanium and GaN

    Energy Technology Data Exchange (ETDEWEB)

    Leyer, Martin; Pristovsek, Markus; Kneissl, Michael [Technische Universitaet Berlin (Germany). Institut fuer Festkoerperphysik

    2010-07-01

    In the last few years accurate values for the optical properties of silicon, germanium and GaN at high temperatures have become important as a reference for in-situ analysis, e.g. reflectometry. Precise temperature dependent dielectric measurements are necessary for the growth of GaInP/GaInAs/Ge triple-junction solar cells and the hetero epitaxy of GaN on silicon and sapphire. We performed spectroscopic ellipsometry (SE) measurements of the dielectric function of silicon, germanium and GaN between 1.5 eV and 6.5 eV in the temperature range from 300 K to 1300 K. The Samples were deoxidized chemically or by heating. High resolution SE spectra were taken every 50 K while cooling down to room temperature. The temperature dependence of the critical energies is compared to literature. Measurements for germanium showed a shift of the E{sub 2} critical point of {proportional_to}0.1 eV toward lower energies. The reason for this behavior is a non-negligible oxide layer on the samples in the literature.

  5. The germanides Er{sub 5}Pd{sub 4}Ge{sub 8} and Tm{sub 5}Pd{sub 4}Ge{sub 8}. 3D [Pd{sub 4}Ge{sub 8}] polyanions with Ge{sub 2} dumb-bells and Ge{sub 4} chains in cis-conformation

    Energy Technology Data Exchange (ETDEWEB)

    Heying, Birgit; Rodewald, Ute C.; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2017-07-01

    Tm{sub 5}Pd{sub 4}Ge{sub 8} was synthesized by melting of the elements in an arc-melting furnace. The new germanide was characterized by powder and single-crystal X-ray diffraction: own structure type, P2{sub 1}/m, a=574.3(1), b=1380.4(3), c=836.4(1) pm, β=107.57(2) , V=0.6321 nm{sup 3}, wR2=0.0578, 2533 F{sup 2} values, 86 variables. The palladium and germanium atoms built up a three-dimensional [Pd{sub 4}Ge{sub 8}]{sup 15-} polyanionic network which contains a unique germanium substructure composed of the Zintl anions Ge{sub 2}{sup 6-} dumb-bells and Ge{sub 4}{sup 10-} chains in cis-conformation. The palladium atoms within the network have distorted square pyramidal germanium coordination. The three crystallographically independent thulium atoms have coordination numbers 15, 16 and 17 with partial motifs of the Frank-Kasper type polyhedra. The isotypic germanide Er{sub 5}Pd{sub 4}Ge{sub 8} forms only after annealing the arc-melted sample at 1070 K for 1 week: a=575.14(9), b=1386.3(3), c=838.4(1) pm, β=107.51(2) , V=0.6375 nm{sup 3}.

  6. Experimental evidence of zone-center optical phonon softening by accumulating holes in thin Ge

    Directory of Open Access Journals (Sweden)

    Shoichi Kabuyanagi

    2016-01-01

    Full Text Available We discuss the impact of free carriers on the zone-center optical phonon frequency in germanium (Ge. By taking advantage of the Ge-on-insulator structure, we measured the Raman spectroscopy by applying back-gate bias. Phonon softening by accumulating holes in Ge film was clearly observed. This fact strongly suggests that the phonon softening in heavily-doped Ge is mainly attributed to the free carrier effect rather than the dopant atom counterpart. Furthermore, we propose that the free carrier effect on phonon softening is simply understandable from the viewpoint of covalent bonding modification by free carriers.

  7. Optical and structural characterization of Ge clusters embedded in ZrO2

    OpenAIRE

    Agocs, E; Zolnai, Z.; Rossall, A. K.; Van den Berg, Jakob; Fodor, B.; Lehninger, D.; Khomenkova, L.; Ponomaryov, S.; Gudymenko, O.; Yukhymchuk, V.; Kalas, B.; Heitmann, J.; Petrik, P.

    2017-01-01

    The change of optical and structural properties of Ge nanoclusters in ZrO2 matrix have been investigated by spectroscopic ellipsometry versus annealing temperatures. Radio-frequency top-down magnetron sputtering approach was used to produce the samples of different types, i.e. single-layers of pure Ge, pure ZrO2 and Ge-rich-ZrO2 as well as multi-layers stacked of 40 periods of 5-nm-Ge-rich-ZrO2 layers alternated by 5-nm-ZrO2 ones. Germanium nanoclusters in ZrO2 host were formed by rapid-therm...

  8. Gas Source Techniques for Molecular Beam Epitaxy of Highly Mismatched Ge Alloys

    OpenAIRE

    Chad A. Stephenson; Miriam Gillett-Kunnath; William A. O’Brien; Robert Kudrawiec; Mark A. Wistey

    2016-01-01

    Ge and its alloys are attractive candidates for a laser compatible with silicon integrated circuits. Dilute germanium carbide (Ge1−xCx) offers a particularly interesting prospect. By using a precursor gas with a Ge4C core, C can be preferentially incorporated in substitutional sites, suppressing interstitial and C cluster defects. We present a method of reproducible and upscalable gas synthesis of tetrakis(germyl)methane, or (H3Ge)4C, followed by the design of a hybrid gas/solid-source molecu...

  9. Plasma-oxidation of Ge(100)-surfaces characterized by MIES, UPS and XPS

    Energy Technology Data Exchange (ETDEWEB)

    Wegewitz, Lienhard; Dahle, Sebastian; Maus-Friedrichs, Wolfgang [Institut fuer Energieforschung und Physikalische Technologien, Technische Universitaet Clausthal, Leibnizstr. 4, 38678 Clausthal-Zellerfeld (Germany); Hoefft, Oliver; Endres, Frank [Institut fuer Mechanische Verfahrenstechnik, Technische Universitaet Clausthal, Arnold-Sommerfeld-Str. 6, 38678 Clausthal-Zellerfeld (Germany); Vioel, Wolfgang [HAWK Goettingen, Fakultaet Naturwissenschaften und Technik, Von-Ossietzky-Str. 99, 37085 Goettingen (Germany)

    2011-07-01

    Cleaning and passivation of Germanium surfaces is of tremendous technological interest. Germanium has various applications, for example in complementary metal-oxide-semiconductor elements. It turned out to be difficult to prepare contamination free Germanium surfaces by methods of wet chemistry. Several attempts have been made preparing such surfaces by different plasma treatments. We report cleaning and passivation of Ge(100)-surfaces by dielectric barrier discharge plasma at ambient temperature in oxygen and in air studied by Metastable Induced Electron Spectroscopy (MIES) and Photoelectron Spectroscopy (UPS(He I) and XPS). The plasma treatment is carried out in a special high-vacuum chamber which operates up to ambient pressure and is directly connected to the ultra-high vacuum chamber including the analysis equipment. In summary the air plasma treatment as well as the oxygen plasma treatment result in contamination free GeO{sub 2} covered surfaces.

  10. Effect of chemical structure on the radioactive decay rate of 71Ge

    International Nuclear Information System (INIS)

    Makariunas, K.; Makariuniene, E.; Dragunas, A.

    1979-01-01

    The influence of the chemical structure on the electron capture radioactive decay rate of 71 Ge was observed. 71 Ge nuclei in bivalent sulphide GeS decay faster than in quadrivalent sulphide GeS 2 . The relative change Δlambda/lambda of the decay constant lambda is + (11.4 +- 1.7) X 10 -4 . A possibility to use the experimental values of Δlambda/lambda to determine the chemical changes in the electron density at germanium nuclei in germanium chemical compounds is discussed. Quantitative determination of the changes in the electron density is complicated because of insufficient reliability of the published values of exchange and overlap corrections to the electron capture probabilities. (Auth.)

  11. Density Functional Theory Calculations Revealing Metal-like Band Structures for Ultrathin Ge {111} and {211} Surface Layers.

    Science.gov (United States)

    Tan, Chih-Shan; Huang, Michael Hsuan-Yi

    2018-05-21

    To find out if germanium should also possess facet-dependent electrical conductivity properties, surface state density functional theory (DFT) calculations were performed on 1-6 layers of Ge (100), (110), (111), and (211) planes. Tunable Ge (100) and (110) planes always present the same semiconducting band structure with a band gap of 0.67 eV expected of bulk germanium. In contrast, 1, 2, 4, and 5 layers of Ge (111) and (211) plane models show metal-like band structures with continuous density of states (DOS) throughout the entire band. For 3 and 6 layers of Ge (111) and (211) plane models, the normal semiconducting band structure was obtained. The plane layers with metal-like band structures also show Ge-Ge bond length deviations and bond distortions, as well as significantly different 4s and 4p frontier orbital electron count and their relative percentages integrated over the valence and conduction bands from those of the semiconducting state. These differences should contribute to strikingly dissimilar band structures. The calculation results suggest observation of facet-dependent electrical conductivity properties of germanium materials, and transistors made of germanium may also need to consider the facet effects with shrinking dimensions approaching 3 nm. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Background suppression in Gerda Phase II and its study in the LArGe low background set-up

    Energy Technology Data Exchange (ETDEWEB)

    Budjas, Dusan [Physik-Department E15, Technische Universitaet Muenchen (Germany); Collaboration: GERDA-Collaboration

    2013-07-01

    In Phase II of the Gerda experiment additional ∝20 kg of BEGe-type germanium detectors, enriched in {sup 76}Ge, will be deployed in liquid argon (LAr) to further increase the sensitivity for the half-life of neutrinoless double beta (0νββ) decay of {sup 76}Ge to > 2 . 10{sup 26} yr. To reduce background by a factor of 10 to the required level of < 10{sup -3} cts/(keV.kg.yr), it is necessary to employ active background-suppression techniques, including anti-Compton veto using scintillation light detection from LAr and pulse shape discrimination exploiting the characteristic electrical field distribution inside BEGe detectors. The latter technique can identify single-site events (typical for 0νββ) and efficiently reject multi-site events (mainly from γ-rays), as well as different types of background events from detector surfaces. The combined power of these techniques was studied for {sup 42}K and other background sources at the low background facility LArGe. Together with extensive simulations, the information from tracking of the Phase II detector material exposure to cosmic rays and based on the background contributions observed in Phase I, the expected background level in Phase II in the region of interest at 2039 keV, the Q{sub ββ} energy of {sup 76}Ge, is estimated. The preliminary analysis shows that contributions from all expected background components after all cuts are in line with the goal of Gerda Phase II.

  13. Schottky barrier parameters and low frequency noise characteristics of graphene-germanium Schottky barrier diode

    Science.gov (United States)

    Khurelbaatar, Zagarzusem; Kil, Yeon-Ho; Shim, Kyu-Hwan; Cho, Hyunjin; Kim, Myung-Jong; Lee, Sung-Nam; Jeong, Jae-chan; Hong, Hyobong; Choi, Chel-Jong

    2016-03-01

    We investigated the electrical properties of chemical vapor deposition-grown monolayer graphene/n-type germanium (Ge) Schottky barrier diodes (SBD) using current-voltage (I-V) characteristics and low frequency noise measurements. The Schottky barrier parameters of graphene/n-type Ge SBDs, such as Schottky barrier height (VB), ideality factor (n), and series resistance (Rs), were extracted using the forward I-V and Cheung's methods. The VB and n extracted from the forward ln(I)-V plot were found to be 0.63 eV and 1.78, respectively. In contrast, from Cheung method, the VB and n were calculated to be 0.53 eV and 1.76, respectively. Such a discrepancy between the values of VB calculated from the forward I-V and Cheung's methods indicated a deviation from the ideal thermionic emission of graphene/n-type Ge SBD associated with the voltage drop across graphene. The low frequency noise measurements performed at the frequencies in the range of 10 Hz-1 kHz showed that the graphene/n-type Ge SBD had 1/f γ frequency dependence, with γ ranging from 1.09 to 1.12, regardless of applied forward biases. Similar to forward-biased SBDs operating in the thermionic emission mode, the current noise power spectral density of graphene/n-type Ge SBD was linearly proportional to the forward current.

  14. Optimization of hetero-epitaxial growth for the threading dislocation density reduction of germanium epilayers

    Science.gov (United States)

    Chong, Haining; Wang, Zhewei; Chen, Chaonan; Xu, Zemin; Wu, Ke; Wu, Lan; Xu, Bo; Ye, Hui

    2018-04-01

    In order to suppress dislocation generation, we develop a "three-step growth" method to heteroepitaxy low dislocation density germanium (Ge) layers on silicon with the MBE process. The method is composed of 3 growth steps: low temperature (LT) seed layer, LT-HT intermediate layer as well as high temperature (HT) epilayer, successively. Threading dislocation density (TDD) of epitaxial Ge layers is measured as low as 1.4 × 106 cm-2 by optimizing the growth parameters. The results of Raman spectrum showed that the internal strain of heteroepitaxial Ge layers is tensile and homogeneous. During the growth of LT-HT intermediate layer, TDD reduction can be obtained by lowering the temperature ramping rate, and high rate deposition maintains smooth surface morphology in Ge epilayer. A mechanism based on thermodynamics is used to explain the TDD and surface morphological dependence on temperature ramping rate and deposition rate. Furthermore, we demonstrate that the Ge layer obtained can provide an excellent platform for III-V materials integrated on Si.

  15. Optimal process parameters for phosphorus spin-on-doping of germanium

    Energy Technology Data Exchange (ETDEWEB)

    Boldrini, Virginia [Dipartimento di Fisica e Astronomia, Università degli Studi di Padova, Via Marzolo 8, I-35131 Padova (Italy); INFN-LNL, Viale dell’Università 2, I-35020 Legnaro, Padova (Italy); Carturan, Sara Maria, E-mail: sara.carturan@lnl.infn.it [Dipartimento di Fisica e Astronomia, Università degli Studi di Padova, Via Marzolo 8, I-35131 Padova (Italy); INFN-LNL, Viale dell’Università 2, I-35020 Legnaro, Padova (Italy); Maggioni, Gianluigi; Napolitani, Enrico [Dipartimento di Fisica e Astronomia, Università degli Studi di Padova, Via Marzolo 8, I-35131 Padova (Italy); INFN-LNL, Viale dell’Università 2, I-35020 Legnaro, Padova (Italy); Napoli, Daniel Ricardo [INFN-LNL, Viale dell’Università 2, I-35020 Legnaro, Padova (Italy); Camattari, Riccardo [INFN Sezione di Ferrara, Dipartimento di Fisica, Università di Ferrara, Via Saragat 1, 44122, Ferrara (Italy); De Salvador, Davide [Dipartimento di Fisica e Astronomia, Università degli Studi di Padova, Via Marzolo 8, I-35131 Padova (Italy); INFN-LNL, Viale dell’Università 2, I-35020 Legnaro, Padova (Italy)

    2017-01-15

    Highlights: • Optimized protocol for the application of phosphorus spin-on-doping to Ge surface. • Homogeneous n-type Ge layers, fully electrically active, are obtained. • Crucial parameters for SOD curing are relative humidity, time and temperature. • Characterization of Ge loss from the surface into the SOD film by diffusion. • Spike annealing in standard tube chamber furnace are performed. - Abstract: The fabrication of homogeneously doped germanium layers characterized by total electrical activation is currently a hot topic in many fields, such as microelectronics, photovoltaics, optics and radiation detectors. Phosphorus spin-on-doping technique has been implemented on Ge wafers, by developing a protocol for the curing process and subsequent diffusion annealing for optimal doping. Parameters such as relative humidity and curing time turned out to affect the surface morphology, the degree of reticulation reached by the dopant source and the amount of dopant available for diffusion. After spike annealing in a conventional furnace, diffusion profiles and electrical properties have been measured. Ge loss from the surface during high-temperature annealing, due to diffusion into the source film, has been observed and quantified.

  16. Monte Carlo modelling of germanium crystals that are tilted and have rounded front edges

    International Nuclear Information System (INIS)

    Gasparro, Joel; Hult, Mikael; Johnston, Peter N.; Tagziria, Hamid

    2008-01-01

    Gamma-ray detection efficiencies and cascade summing effects in germanium detectors are often calculated using Monte Carlo codes based on a computer model of the detection system. Such a model can never fully replicate reality and it is important to understand how various parameters affect the results. This work concentrates on quantifying two issues, namely (i) the effect of having a Ge-crystal that is tilted inside the cryostat and (ii) the effect of having a model of a Ge-crystal with rounded edges (bulletization). The effect of the tilting is very small (in the order of per mille) when the tilting angles are within a realistic range. The effect of the rounded edges is, however, relatively large (5-10% or higher) particularly for gamma-ray energies below 100 keV

  17. Monte Carlo modelling of germanium crystals that are tilted and have rounded front edges

    Energy Technology Data Exchange (ETDEWEB)

    Gasparro, Joel [EC-JRC-IRMM, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel (Belgium); Hult, Mikael [EC-JRC-IRMM, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel (Belgium)], E-mail: mikael.hult@ec.europa.eu; Johnston, Peter N. [Applied Physics, Royal Melbourne Institute of Technology, GPO Box 2476V, Melbourne 3001 (Australia); Tagziria, Hamid [EC-JRC-IPSC, Institute for the Protection and the Security of the Citizen, Via E. Fermi 1, I-21020 Ispra (Vatican City State, Holy See,) (Italy)

    2008-09-01

    Gamma-ray detection efficiencies and cascade summing effects in germanium detectors are often calculated using Monte Carlo codes based on a computer model of the detection system. Such a model can never fully replicate reality and it is important to understand how various parameters affect the results. This work concentrates on quantifying two issues, namely (i) the effect of having a Ge-crystal that is tilted inside the cryostat and (ii) the effect of having a model of a Ge-crystal with rounded edges (bulletization). The effect of the tilting is very small (in the order of per mille) when the tilting angles are within a realistic range. The effect of the rounded edges is, however, relatively large (5-10% or higher) particularly for gamma-ray energies below 100 keV.

  18. Ion-beam doping of amorphous silicon with germanium isovalent impurity

    International Nuclear Information System (INIS)

    Khokhlov, A.F.; Mashin, A.I.; Ershov, A.V.; Mashin, N.I.; Ignat'eva, E.A.

    1988-01-01

    Experimental data on ion-beam doping of amorphous silicon containing minor germanium additions by donor and acceptor impurity are presented. Doping of a-Si:Ge films as well as of a-Si layers was performed by implantation of 40 keV energy B + ions or 120 keV energy phosphorus by doses from 3.2x10 13 up to 1.3x10 17 cm -2 . Ion current density did not exceed 1 μA/cm 2 . Radiation defect annealing was performed at 400 deg C temperature during 30 min. Temperature dependences of conductivity in the region of 160-500 K were studied. It is shown that a-Si:Ge is like hydrogenized amorphous silicon in relation to doping

  19. Timing of gamma rays in coaxial germanium detector systems

    International Nuclear Information System (INIS)

    El-Ibiary, M.Y.

    1979-01-01

    A study is reported on the timing uncertainty in gamma ray coaxial germanium detector systems. The work deals with the zero cross over method which is widely used to reduce the dependence of the instant of timing on the radiation energy absorbed and on the position within the detector at which absorption takes place. It is found that the amplitude risetime compensated (ARC) method gives, under normal conditions, the best resolution at a specific energy. For higher energies, the resolution improves and there is no shift of the mean instant of timing. The method is therefore well suited for wide energy coverage. The parameters involved in implementing an ARC system for optimum performance at a specific energy are identified in terms of the preamplifier noise level and risetime. A trade off can be made between the resolutions at high and at low energies. The time resolution attained is given by means of a series of charts which use normalized dimensionless variables for ready application to any given case. Lithium compensated Ge detectors which normally operate under conditions of velocity saturation of the charge carriers by applying sufficient bias voltage create an electric field in excess of 1 kV/cm throughout the depleted region. High purity Ge detectors where velocity saturation may not be reached within certain parts of the depleted region are studied. Special attention is given to the probability of pulses being incorrectly timed because of their slow rise or small magnitude. Such incorrect timing is energy-dependent and results in a noticeable distortion of the timing spectrum that relates to a wide energy range. Limitations on system parameters to keep the probability of incorrect timing below a specified fraction are given

  20. Liquid argon as active shielding and coolant for bare germanium detectors. A novel background suppression method for the GERDA 0νββ experiment

    International Nuclear Information System (INIS)

    Peiffer, J.P.

    2007-01-01

    Two of the most important open questions in particle physics are whether neutrinos are their own anti-particles (Majorana particles) as required by most extensions of the StandardModel and the absolute values of the neutrino masses. The neutrinoless double beta (0νββ) decay, which can be investigated using 76 Ge (a double beta isotope), is the most sensitive probe for these properties. There is a claim for an evidence for the 0νββ decay in the Heidelberg-Moscow (HdM) 76 Ge experiment by a part of the HdM collaboration. The new 76 Ge experiment Gerda aims to check this claim within one year with 15 kg.y of statistics in Phase I at a background level of ≤10 -2 events/(kg.keV.y) and to go to higher sensitivity with 100 kg.y of statistics in Phase II at a background level of ≤10 -3 events/(kg.keV.y). In Gerda bare germanium semiconductor detectors (enriched in 76 Ge) will be operated in liquid argon (LAr). LAr serves as cryogenic coolant and as high purity shielding against external background. To reach the background level for Phase II, new methods are required to suppress the cosmogenic background of the diodes. The background from cosmogenically produced 60 Co is expected to be ∝2.5.10 -3 events/(kg.keV.y). LAr scintillates in UV (λ=128 nm) and a novel concept is to use this scintillation light as anti-coincidence signal for background suppression. In this work the efficiency of such a LAr scintillation veto was investigated for the first time. In a setup with 19 kg active LAr mass a suppression of a factor 3 has been achieved for 60 Co and a factor 17 for 232 Th around Q ββ = 2039 keV. This suppression will further increase for a one ton active volume (factor O(100) for 232 Th and 60 Co). LAr scintillation can also be used as a powerful tool for background diagnostics. For this purpose a new, very stable and robust wavelength shifter/reflector combination for the light detection has been developed, leading to a photo electron (pe) yield of as much as

  1. Liquid argon as active shielding and coolant for bare germanium detectors. A novel background suppression method for the GERDA 0{nu}{beta}{beta} experiment

    Energy Technology Data Exchange (ETDEWEB)

    Peiffer, J.P.

    2007-07-25

    Two of the most important open questions in particle physics are whether neutrinos are their own anti-particles (Majorana particles) as required by most extensions of the StandardModel and the absolute values of the neutrino masses. The neutrinoless double beta (0{nu}{beta}{beta}) decay, which can be investigated using {sup 76}Ge (a double beta isotope), is the most sensitive probe for these properties. There is a claim for an evidence for the 0{nu}{beta}{beta} decay in the Heidelberg-Moscow (HdM) {sup 76}Ge experiment by a part of the HdM collaboration. The new {sup 76}Ge experiment Gerda aims to check this claim within one year with 15 kg.y of statistics in Phase I at a background level of {<=}10{sup -2} events/(kg.keV.y) and to go to higher sensitivity with 100 kg.y of statistics in Phase II at a background level of {<=}10{sup -3} events/(kg.keV.y). In Gerda bare germanium semiconductor detectors (enriched in {sup 76}Ge) will be operated in liquid argon (LAr). LAr serves as cryogenic coolant and as high purity shielding against external background. To reach the background level for Phase II, new methods are required to suppress the cosmogenic background of the diodes. The background from cosmogenically produced {sup 60}Co is expected to be {proportional_to}2.5.10{sup -3} events/(kg.keV.y). LAr scintillates in UV ({lambda}=128 nm) and a novel concept is to use this scintillation light as anti-coincidence signal for background suppression. In this work the efficiency of such a LAr scintillation veto was investigated for the first time. In a setup with 19 kg active LAr mass a suppression of a factor 3 has been achieved for {sup 60}Co and a factor 17 for {sup 232}Th around Q{sub {beta}}{sub {beta}} = 2039 keV. This suppression will further increase for a one ton active volume (factor O(100) for {sup 232}Th and {sup 60}Co). LAr scintillation can also be used as a powerful tool for background diagnostics. For this purpose a new, very stable and robust wavelength

  2. Astroparticle physics with a customized low-background broad energy Germanium detector

    Energy Technology Data Exchange (ETDEWEB)

    Aalseth, Craig E.; Amman, M.; Avignone, Frank T.; Back, Henning O.; Barabash, Alexander S.; Barbeau, P. S.; Bergevin, M.; Bertrand, F.; Boswell, M.; Brudanin, V.; Bugg, William; Burritt, Tom H.; Busch, Matthew; Capps, Greg L.; Chan, Yuen-Dat; Collar, J. I.; Cooper, R. J.; Creswick, R.; Detwiler, Jason A.; Diaz, J.; Doe, Peter J.; Efremenko, Yuri; Egorov, Viatcheslav; Ejiri, H.; Elliott, Steven R.; Ely, James H.; Esterline, James H.; Farach, H. A.; Fast, James E.; Fields, N.; Finnerty, P.; Fujikawa, Brian; Fuller, Erin S.; Gehman, Victor M.; Giovanetti, G. K.; Guiseppe, Vincente; Gusey, K.; Hallin, A. L.; Harper, Gregory; Hazama, R.; Henning, Reyco; Hime, Andrew; Hoppe, Eric W.; Hossbach, Todd W.; Howe, M. A.; Johnson, R. A.; Keeter, K.; Keillor, Martin E.; Keller, C.; Kephart, Jeremy D.; Kidd, Mary; Knecht, A.; Kochetov, Oleg; Konovalov, S.; Kouzes, Richard T.; Leviner, L.; Loach, J. C.; Luke, P.; MacMullin, S.; Marino, Michael G.; Martin, R. D.; Mei, Dong-Ming; Miley, Harry S.; Miller, M. L.; Mizouni, Leila; Myers, Allan W.; Nomachi, Masaharu; Orrell, John L.; Peterson, David; Phillips, D.; Poon, Alan; Prior, Gersende; Qian, J.; Radford, D. C.; Rielage, Keith; Robertson, R. G. H.; Rodriguez, Larry; Rykaczewski, Krzysztof P.; Salazar, Harold; Schubert, Alexis G.; Shima, T.; Shirchenko, M.; Steele, David; Strain, J.; Swift, Gary; Thomas, K.; Timkin, V.; Tornow, W.; Van Wechel, T. D.; Vanyushin, I.; Varner, R. L.; Vetter, Kai; Wilkerson, J. F.; Wolfe, B. A.; Xiang, W.; Yakushev, E.; Yaver, Harold; Young, A.; Yu, Chang-Hong; Yumatov, Vladimir; Zhang, C.; Zimmerman, S.

    2011-10-01

    The Majorana Collaboration is building the Majorana Demonstrator, a 60 kg array of high purity germanium detectors housed in an ultra-low background shield at the Sanford Underground Laboratory in Lead, SD. The Majorana Demonstrator will search for neutrinoless double-beta decay of 76Ge while demonstrating the feasibility of a tonne-scale experiment. It may also carry out a dark matter search in the 1-10 GeV/c² mass range. We have found that customized Broad Energy Germanium (BEGe) detectors produced by Canberra have several desirable features for a neutrinoless double-beta decay experiment, including low electronic noise, excellent pulse shape analysis capabilities, and simple fabrication. We have deployed a customized BEGe, the Majorana Low-Background BEGe at Kimballton (MALBEK), in a low-background cryostat and shield at the Kimballton Underground Research Facility in Virginia. This paper will focus on the detector characteristics and measurements that can be performed with such a radiation detector in a low-background environment.

  3. Evaluation Of The Impact Of The Defense Waste Processing Facility (DWPF) Laboratory Germanium Oxide Use On Recycle Transfers To The H-Tank Farm

    International Nuclear Information System (INIS)

    Jantzen, C.; Laurinat, J.

    2011-01-01

    When processing High Level Waste (HLW) glass, the Defense Waste Processing Facility (DWPF) cannot wait until the melt or waste glass has been made to assess its acceptability, since by then no further changes to the glass composition and acceptability are possible. Therefore, the acceptability decision is made on the upstream feed stream, rather than on the downstream melt or glass product. This strategy is known as 'feed forward statistical process control.' The DWPF depends on chemical analysis of the feed streams from the Sludge Receipt and Adjustment Tank (SRAT) and the Slurry Mix Evaporator (SME) where the frit plus adjusted sludge from the SRAT are mixed. The SME is the last vessel in which any chemical adjustments or frit additions can be made. Once the analyses of the SME product are deemed acceptable, the SME product is transferred to the Melter Feed Tank (MFT) and onto the melter. The SRAT and SME analyses have been analyzed by the DWPF laboratory using a 'Cold Chemical' method but this dissolution did not adequately dissolve all the elemental components. A new dissolution method which fuses the SRAT or SME product with cesium nitrate (CsNO 3 ), germanium (IV) oxide (GeO 2 ) and cesium carbonate (Cs 2 CO 3 ) into a cesium germanate glass at 1050 C in platinum crucibles has been developed. Once the germanium glass is formed in that fusion, it is readily dissolved by concentrated nitric acid (about 1M) to solubilize all the elements in the SRAT and/or SME product for elemental analysis. When the chemical analyses are completed the acidic cesium-germanate solution is transferred from the DWPF analytic laboratory to the Recycle Collection Tank (RCT) where the pH is increased to ∼12 M to be released back to the tank farm and the 2H evaporator. Therefore, about 2.5 kg/yr of GeO 2 /year will be diluted into 1.4 million gallons of recycle. This 2.5 kg/yr of GeO 2 may increase to 4 kg/yr when improvements are implemented to attain an annual canister production

  4. Vacancy-indium clusters in implanted germanium

    KAUST Repository

    Chroneos, Alexander I.

    2010-04-01

    Secondary ion mass spectroscopy measurements of heavily indium doped germanium samples revealed that a significant proportion of the indium dose is immobile. Using electronic structure calculations we address the possibility of indium clustering with point defects by predicting the stability of indium-vacancy clusters, InnVm. We find that the formation of large clusters is energetically favorable, which can explain the immobility of the indium ions. © 2010 Elsevier B.V. All rights reserved.

  5. Vacancy-indium clusters in implanted germanium

    KAUST Repository

    Chroneos, Alexander I.; Kube, R.; Bracht, Hartmut A.; Grimes, Robin W.; Schwingenschlö gl, Udo

    2010-01-01

    Secondary ion mass spectroscopy measurements of heavily indium doped germanium samples revealed that a significant proportion of the indium dose is immobile. Using electronic structure calculations we address the possibility of indium clustering with point defects by predicting the stability of indium-vacancy clusters, InnVm. We find that the formation of large clusters is energetically favorable, which can explain the immobility of the indium ions. © 2010 Elsevier B.V. All rights reserved.

  6. Strained silicon/silicon germanium heterojunction n-channel metal oxide semiconductor field effect transistors

    International Nuclear Information System (INIS)

    Olsen, Sarah H.

    2002-01-01

    Investigations into the performance of strained silicon/silicon-germanium (Si/SiGe) n-channel metal-oxide-semiconductor field effect transistors (MOSFETs) have been carried out. Theoretical predictions suggest that use of a strained Si/SiGe material system with advanced material properties compared with conventional silicon allows enhanced MOSFET device performance. This study has therefore investigated the practical feasibility of obtaining superior electrical performance using a Si/SiGe material system. The MOSFET devices consisted of a strained Si surface channel and were fabricated on relaxed SiGe material using a reduced thermal budget process in order to preserve the strain. Two batches of strained Si/SiGe devices fabricated on material grown by differing methods have been analysed and both showed good transistor action. A correlation of electrical and physical device data established that the electrical device behaviour was closely related to the SiGe material quality, which differed depending on growth technique. The cross-wafer variation in the electrical performance of the strained Si/SiGe devices was found to be a function of material quality, thus the viability of Si/SiGe MOSFET technology for commercial applications has been addressed. Of particular importance was the finding that large-scale 'cross-hatching' roughness associated with relaxed SiGe alloys led to degradation in the small-scale roughness at the gate oxide interface, which affects electrical device performance. The fabrication of strained Si MOSFET devices on high quality SiGe material thus enabled significant performance gains to be realised compared with conventional Si control devices. In contrast, the performance of devices fabricated on material with severe cross-hatching roughness was found to be diminished by the nanoscale oxide interface roughness. The effect of device processing on SiGe material with differing as-grown roughness has been carried out and compared with the reactions

  7. Isotope enrichment

    International Nuclear Information System (INIS)

    Lydtin, H-J.; Wilden, R.J.; Severin, P.J.W.

    1978-01-01

    The isotope enrichment method described is based on the recognition that, owing to mass diffusion and thermal diffusion in the conversion of substances at a heated substrate while depositing an element or compound onto the substrate, enrichment of the element, or a compound of the element, with a lighter isotope will occur. The cycle is repeated for as many times as is necessary to obtain the degree of enrichment required

  8. Uranium enrichment

    International Nuclear Information System (INIS)

    1990-01-01

    This report looks at the following issues: How much Soviet uranium ore and enriched uranium are imported into the United States and what is the extent to which utilities flag swap to disguise these purchases? What are the U.S.S.R.'s enriched uranium trading practices? To what extent are utilities required to return used fuel to the Soviet Union as part of the enriched uranium sales agreement? Why have U.S. utilities ended their contracts to buy enrichment services from DOE?

  9. Investigation of electrochemical reduction of GeO2 to Ge in molten CaCl2-NaCl

    International Nuclear Information System (INIS)

    Rong, Liangbin; He, Rui; Wang, Zhiyong; Peng, Junjun; Jin, Xianbo; Chen, George Z.

    2014-01-01

    Electrochemical reduction of solid GeO 2 has been investigated in the mixed CaCl 2 -NaCl melt at 1023 K for developing a more efficient process for preparation of Ge. Cyclic voltammetry and potentiostatic electrolysis were applied to study the GeO 2 -loaded metallic cavity electrode. In addition, porous GeO 2 pellets were reduced by potentiostatic and constant cell voltage electrolysis with a graphite anode, and the electrolysis products were analyzed by powder X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectrometry, focusing on understanding the reduction mechanism and the impact of electrode potential on the product purity. It was found that the reduction of GeO 2 to Ge occurred at a potential of about -0.50 V (vs. Ag/Ag + ), but generating various calcium germanates simultaneously, whose reduction was a little more difficult and needed a potential more negative than -1.00 V. However, if the cathode potential exceeded -1.60 V, Ca (or Na) - Ge intermetallic compounds might form. These results gave an appropriate potential range between -1.10 and -1.40 V for the production of pure germanium. Rapid electrolysis of GeO 2 to pure Ge has been realized at a cell voltage of 2.5 V with a current efficiency of about 92%

  10. Investigation of germanium implanted with aluminum by multi-laser micro-Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sanson, A., E-mail: andrea.sanson@unipd.it [Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Napolitani, E. [MATIS IMM-CNR at Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Impellizzeri, G. [MATIS IMM-CNR and Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Giarola, M. [Dipartimento di Informatica, Università di Verona, Strada le Grazie 15, I-37134 Verona (Italy); De Salvador, D. [Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Privitera, V.; Priolo, F. [MATIS IMM-CNR and Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Mariotto, G. [Dipartimento di Informatica, Università di Verona, Strada le Grazie 15, I-37134 Verona (Italy); Carnera, A. [Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy)

    2013-08-31

    Germanium samples, implanted with aluminum and annealed, have been investigated by micro-Raman spectroscopy using different excitation lines with the aim of gaining insights about the Al distribution at different depths beneath the sample surface and to correlate the Raman spectra with the electrical and chemical profiles, obtained by Spreading Resistance Profiling (SRP) and Secondary Ions Mass Spectrometry (SIMS) measurements, respectively. The intensity of the Al–Ge Raman peak at about 370 cm{sup −1}, due to the local vibrational mode of the substitutional Al atoms in the Ge matrix, has been directly related to the SRP behavior, while no correlation has been observed with SIMS profiles. These findings show that the electrically active content is entirely due to the substitutional Al atoms. Finally, a clear down shift is observed for the Ge–Ge Raman peak at ∼ 300 cm{sup −1}, which also seems to be directly related to the active content of Al dopant atoms. This work shows that micro-Raman spectroscopy can be a suitable tool for the study of doping profiles in Ge. - Highlights: ► Al-implanted Ge and annealed were studied by micro-Raman spectroscopy. ► Using different laser lines we have investigated the implants at different depths. ► The Al–Ge Raman peak at about 370 cm{sup −1} is directly related to the SRP behavior. ► The electrically active content is entirely due to the substitutional Al atoms. ► Carrier effects are observed on the Ge–Ge peak at ∼ 300 cm{sup −1}.

  11. Investigation of germanium implanted with aluminum by multi-laser micro-Raman spectroscopy

    International Nuclear Information System (INIS)

    Sanson, A.; Napolitani, E.; Impellizzeri, G.; Giarola, M.; De Salvador, D.; Privitera, V.; Priolo, F.; Mariotto, G.; Carnera, A.

    2013-01-01

    Germanium samples, implanted with aluminum and annealed, have been investigated by micro-Raman spectroscopy using different excitation lines with the aim of gaining insights about the Al distribution at different depths beneath the sample surface and to correlate the Raman spectra with the electrical and chemical profiles, obtained by Spreading Resistance Profiling (SRP) and Secondary Ions Mass Spectrometry (SIMS) measurements, respectively. The intensity of the Al–Ge Raman peak at about 370 cm −1 , due to the local vibrational mode of the substitutional Al atoms in the Ge matrix, has been directly related to the SRP behavior, while no correlation has been observed with SIMS profiles. These findings show that the electrically active content is entirely due to the substitutional Al atoms. Finally, a clear down shift is observed for the Ge–Ge Raman peak at ∼ 300 cm −1 , which also seems to be directly related to the active content of Al dopant atoms. This work shows that micro-Raman spectroscopy can be a suitable tool for the study of doping profiles in Ge. - Highlights: ► Al-implanted Ge and annealed were studied by micro-Raman spectroscopy. ► Using different laser lines we have investigated the implants at different depths. ► The Al–Ge Raman peak at about 370 cm −1 is directly related to the SRP behavior. ► The electrically active content is entirely due to the substitutional Al atoms. ► Carrier effects are observed on the Ge–Ge peak at ∼ 300 cm −1

  12. Atomic-scale structure of GeSe2 glass revisited: a continuous or broken network of Ge-(Se1/2)4 tetrahedra?

    International Nuclear Information System (INIS)

    Petkov, V; Le Messurier, D

    2010-01-01

    The atomic-scale structure of germanium diselenide (GeSe 2 ) glass has been revisited using a combination of high-energy x-ray diffraction and constrained reverse Monte Carlo simulations. The study shows that the glass structure may be very well described in terms of a continuous network of corner- and edge-sharing Ge-Se 4 tetrahedra. The result is in contrast to other recent studies asserting that the chemical order and, hence, network integrity in GeSe 2 glass are intrinsically broken. It is suggested that more elaborate studies are necessary to resolve the controversy.

  13. Water soluble nano-scale transient material germanium oxide for zero toxic waste based environmentally benign nano-manufacturing

    KAUST Repository

    Almuslem, A. S.

    2017-02-14

    In the recent past, with the advent of transient electronics for mostly implantable and secured electronic applications, the whole field effect transistor structure has been dissolved in a variety of chemicals. Here, we show simple water soluble nano-scale (sub-10 nm) germanium oxide (GeO) as the dissolvable component to remove the functional structures of metal oxide semiconductor devices and then reuse the expensive germanium substrate again for functional device fabrication. This way, in addition to transiency, we also show an environmentally friendly manufacturing process for a complementary metal oxide semiconductor (CMOS) technology. Every year, trillions of complementary metal oxide semiconductor (CMOS) electronics are manufactured and billions are disposed, which extend the harmful impact to our environment. Therefore, this is a key study to show a pragmatic approach for water soluble high performance electronics for environmentally friendly manufacturing and bioresorbable electronic applications.

  14. Phase transformations in chalkogenides of germanium subgroup elements and in alloys on their base at high pressures

    International Nuclear Information System (INIS)

    Skums, V.F.; Skoropanov, A.S.; Vecher, A.A.

    1990-01-01

    An attempt was made to systematize and analyze the available data on behaviour of chalkogenides of germanium subgroup elements and their alloys at high pressures, as applied to the problem of their use as reference materials for pressure determination. It is shown that phase transformations, accompanied by sharp change of electric resistance, are observed in chalkogenides of cubic and rhombohedral structures (lead, tin (SnTe) and germanium (GeTe)) under the effect of high pressures. It was established that electric resistance in the region of phase transformation (electric signal) depended on the type and concentration of current carriers: electric sigual grew with decrease of current carrier concentration; substances with p-type of conductivity were characterized by lower electric signal, as compared to substances with n-conductivety

  15. Magnetic behavior of Si-Ge bond in SixGe4-x nano-clusters

    Science.gov (United States)

    Nahali, Masoud; Mehri, Ali

    2018-06-01

    The structure of SixGe4-x nano-clusters were optimized by MPW1B95 level of theory using MG3S and SDB-aug-cc-PVTZ basis set. The agreement of the calculated ionization and dissociation energies with experimental values validates the reported structures of nano-clusters and justifies the use of hybrid meta density functional method. Since the Si-Si bond is stronger than Si-Ge and Ge-Ge bonds, the Si-Si, Si-Ge, and Ge-Ge diagonal bonds determine the precedence of the stability in these nano-clusters. The hybrid meta density functional calculations were carried out to investigate the adsorption of CO on all possible SixGe4-x nano-clusters. It was found that the silicon atom generally makes a stronger bond with CO than germanium and thereby preferentially affects the shape of structures having higher multiplicity. In Si-Ge structures with higher spin more than 95% of spins accumulate on positions with less bonds to other atoms of the cluster. Through CO adsorption on these clusters bridge structures are made that behave as spin bridge which conduct the spin from the nano-cluster surface to the adsorbate atoms. A better understanding of bridged structures was achieved upon introducing the 'spin bridge' concept. Based on exhaustive spin density analysis, it was found that the reason for the extra negative charge on oxygen in the bridged structures is the relocation of spin from the surface through the bridge.

  16. On the crystallization of amorphous germanium films

    Science.gov (United States)

    Edelman, F.; Komem, Y.; Bendayan, M.; Beserman, R.

    1993-06-01

    The incubation time for crystallization of amorphous Ge (a-Ge) films, deposited by e-gun, was studied as a function of temperature between 150 and 500°C by means of both in situ transmission electron microscopy and Raman scattering spectroscopy. The temperature dependence of t0 follows an Arrhenius curve with an activation energy of 2.0 eV for free-sustained a-Ge films. In the case where the a-Ge films were on Si 3N 4 substrate, the activation energy of the incubation process was 1.3 eV.

  17. Uranium enrichment

    International Nuclear Information System (INIS)

    1989-01-01

    GAO was asked to address several questions concerning a number of proposed uranium enrichment bills introduced during the 100th Congress. The bill would have restructured the Department of Energy's uranium enrichment program as a government corporation to allow it to compete more effectively in the domestic and international markets. Some of GAO's findings discussed are: uranium market experts believe and existing market models show that the proposed DOE purchase of a $750 million of uranium from domestic producers may not significantly increase production because of large producer-held inventories; excess uranium enrichment production capacity exists throughout the world; therefore, foreign producers are expected to compete heavily in the United States throughout the 1990s as utilities' contracts with DOE expire; and according to a 1988 agreement between DOE's Offices of Nuclear Energy and Defense Programs, enrichment decommissioning costs, estimated to total $3.6 billion for planning purposes, will be shared by the commercial enrichment program and the government

  18. Understanding rhizosphere processes to enhance phytoextraction of germanium and rare earth elements

    Science.gov (United States)

    Wiche, Oliver

    2017-04-01

    Germanium (Ge) and rare earth elements (REEs) are economically valuable raw materials that are not actually rare in terms of concentrations in soils but they are hardly available for plant uptake due to interactions with organic matter (SOM), secondary soil constituents such as Fe/Mn oxides and P bearing soil fractions. Processes in the rhizosphere might influence availability of Ge and REEs in the soil-plant system, since lowering of the pH and presence of carboxylates and siderophores (small molecules that strongly chelate Fe and other elements) strongly influences the chemical speciation of Ge and REEs in soil and consequently this comprehensive knowledge helps us to improve phytomining. In a series of field and greenhouse experiments 16 plant species from the functional groups of grasses, herbs and legumes were tested with regard to their accumulation efficiency of Ge and REEs in shoots. Subsequently, we conducted mixed culture experiments in which inefficient species (e.g. cereals like Avena sativa, Hordeum vulgare, Panicum miliaceum) were cultivated in mixed cultures with efficient species (Lupinus albus, Lupinus angustifolius). Based on the plant concentrations a principal component analysis (PCA) was performed to identify significant factors that explain the accumulation behavior of different plant species with regard to Ge, REEs, Si, Fe and Mn. In this analysis Mn was used to identify plant species with efficient mechanisms to access sparingly available P-resources in soils. Particularly in nonmycorrhizal species concentrations of Mn in leaves often indicate a carboxylate based P-mobilising strategy. Herbaceous plant species accumulated significantly higher amounts of REEs while grasses accumulated significantly higher amounts of Ge. Concentrations of Ge in shoots of grasses correlated significantly positive with Si, but negatively with concentrations of Mn. Indeed, the results of the PCA clearly show that plants with high Mn concentrations tend to have

  19. Protein patterning on polycrystalline silicon-germanium via standard UV lithography for bioMEMS applications

    Energy Technology Data Exchange (ETDEWEB)

    Lenci, S., E-mail: silvia.lenci@gmail.com [Dipartimento di Ingegneria dell' Informazione, University of Pisa, Via G. Caruso 16, I-56122 Pisa (Italy); imec, Kapeldreef 75, Leuven B-3001 (Belgium); Tedeschi, L.; Domenici, C.; Lande, C. [Istituto di Fisiologia Clinica, CNR, via G. Moruzzi 1, Pisa I-56124 (Italy); Nannini, A.; Pennelli, G.; Pieri, F. [Dipartimento di Ingegneria dell' Informazione, University of Pisa, Via G. Caruso 16, I-56122 Pisa (Italy); Severi, S. [imec, Kapeldreef 75, Leuven B-3001 (Belgium)

    2010-10-12

    Polycrystalline silicon-germanium (poly-SiGe) is a promising structural material for the post-processing of micro electro-mechanical systems (MEMS) on top of complementary metal-oxide-semiconductor (CMOS) substrates. Combining MEMS and CMOS allows for the development of high-performance devices. We present for the first time selective protein immobilization on top of poly-SiGe surfaces, an enabling technique for the development of novel poly-SiGe based MEMS biosensors. Active regions made of 3-aminopropyl-triethoxysilane (APTES) were defined using silane deposition onto photoresist patterns followed by lift-off in organic solvents. Subsequently, proteins were covalently bound on the created APTES patterns. Fluorescein-labeled human serum albumin (HSA) was used to verify the immobilization procedure while the binding capability of the protein layer was tested by an antigen-labeled antibody pair. Inspection by fluorescence microscopy showed protein immobilization inside the desired bioactive areas and low non-specific adsorption outside the APTES pattern. Furthermore, the quality of the silane patches was investigated by treatment with 30 nm-diameter gold nanoparticles and scanning electron microscope observation. The developed technique is therefore a promising first step towards the realization of poly-SiGe based biosensors.

  20. Polarization-sensitive and broadband germanium sulfide photodetectors with excellent high-temperature performance.

    Science.gov (United States)

    Tan, Dezhi; Zhang, Wenjin; Wang, Xiaofan; Koirala, Sandhaya; Miyauchi, Yuhei; Matsuda, Kazunari

    2017-08-31

    Layered materials, such as graphene, transition metal dichalcogenides and black phosphorene, have been established rapidly as intriguing building blocks for optoelectronic devices. Here, we introduce highly polarization sensitive, broadband, and high-temperature-operation photodetectors based on multilayer germanium sulfide (GeS). The GeS photodetector shows a high photoresponsivity of about 6.8 × 10 3 A W -1 , an extremely high specific detectivity of 5.6 × 10 14 Jones, and broad spectral response in the wavelength range of 300-800 nm. More importantly, the GeS photodetector has high polarization sensitivity to incident linearly polarized light, which provides another degree of freedom for photodetectors. Tremendously enhanced photoresponsivity is observed with a temperature increase, and high responsivity is achievable at least up to 423 K. The establishment of larger photoinduced reduction of the Schottky barrier height will be significant for the investigation of the photoresponse mechanism of 2D layered material-based photodetectors. These attributes of high photocurrent generation in a wide temperature range, broad spectral response, and polarization sensitivity coupled with environmental stability indicate that the proposed GeS photodetector is very suitable for optoelectronic applications.

  1. Modeling and Analysis of Entropy Generation in Light Heating of Nanoscaled Silicon and Germanium Thin Films

    Directory of Open Access Journals (Sweden)

    José Ernesto Nájera-Carpio

    2015-07-01

    Full Text Available In this work, the irreversible processes in light heating of Silicon (Si and Germanium (Ge thin films are examined. Each film is exposed to light irradiation with radiative and convective boundary conditions. Heat, electron and hole transport and generation-recombination processes of electron-hole pairs are studied in terms of a phenomenological model obtained from basic principles of irreversible thermodynamics. We present an analysis of the contributions to the entropy production in the stationary state due to the dissipative effects associated with electron and hole transport, generation-recombination of electron-hole pairs as well as heat transport. The most significant contribution to the entropy production comes from the interaction of light with the medium in both Si and Ge. This interaction includes two processes, namely, the generation of electron-hole pairs and the transferring of energy from the absorbed light to the lattice. In Si the following contribution in magnitude comes from the heat transport. In Ge all the remaining contributions to entropy production have nearly the same order of magnitude. The results are compared and explained addressing the differences in the magnitude of the thermodynamic forces, Onsager’s coefficients and transport properties of Si and Ge.

  2. One-pot size-controlled growth of graphene-encapsulated germanium nanocrystals

    Science.gov (United States)

    Lee, Jae-Hyun; Lee, Eun-Kyung; Kang, Seog-Gyun; Jung, Su-Ho; Son, Seok-Kyun; Nam, Woo Hyun; Kim, Tae-Hoon; Choi, Byong Lyong; Whang, Dongmok

    2018-05-01

    To realize graphene-encapsulated semiconductor nanocrystals (NCs), an additional graphene coating process, which causes shape destruction and chemical contamination, has so far been inevitable. We report herein one-pot growth of uniform graphene-germanium core-shell nanocrystals (Ge@G NCs) in gram scale by the addition of methane as a carbon source during the thermal pyrolysis of germane. The methane plays a critical role in the growth of the graphene shell, as well as in the determination of the nucleation density and diameter of the NCs, similar to a surfactant in the liquid-phase growth of monodisperse NCs. By adjusting the gas ratio of precursors, a mixture of germane and methane, we can control the size of the Ge@G NCs in the range of ∼5-180 nm. The Ge@G NCs were characterized by various microscopic and spectroscopic tools, which indicated that the Ge core is single crystalline, and is completely covered by the graphene shell. We further investigated the merits of the graphene shell, which can enhance the electrical conductivity of nanocrystalline materials.

  3. Damage resistance of AR-coated germanium surfaces for nanosecond CO2 laser pulses

    International Nuclear Information System (INIS)

    Newnam, B.E.; Gill, D.H.

    1977-01-01

    An evaluation of the state-of-the-art of AR coatings on gallium-doped germanium, used as a saturable absorber at 10.6 μm, has been conducted. Both 1-on-1 and N-on-1 laser damage thresholds were measured with 1.2 ns pulses on bare and coated surfaces. Only front surface damage was observed. With few exceptions, the thresholds for coated surfaces were centered at 0.49 +- 0.3 J/cm 2 . Bare Ge had a threshold ranging from 0.65 to 0.70 J/cm 2 . No significant differences due to substrate polish, crystallinity or doping level were evident and multiple-shot conditioning resulted in the same threshold as for single shot tests. From an analysis of standing-wave electric fields, damage for AR-coated Ge appeared to be limited by the surface properties of Ge. Measurements at both 1.2 and 70 ns indicated that the threshold (J/cm 2 ) of both coated and uncoated Ge increases as the square root of the pulse-width

  4. Processing and optical characterization of lead calcium titanate borosilicate glass doped with germanium

    Science.gov (United States)

    Gautam, C. R.; Das, Sangeeta; Gautam, S. S.; Madheshiya, Abhishek; Singh, Anod Kumar

    2018-04-01

    In this study, various compositions of lead calcium titanate borosilicate glass doped with a fixed amount of germanium were synthesized using the rapid melt quench technique. The amorphous nature of the synthesized glass was confirmed by X-ray diffraction and scanning electron microscopy analyses. The structural and optical properties were deduced using Raman, Fourier transform infrared (FTIR), and ultraviolet-visible (UV-Vis) spectroscopy. FTIR spectroscopy confirmed the presence of borate groups in triangular and tetrahedral coordination. Infrared and Raman analyses detected the vibrational bonds of Gesbnd Osbnd Ge, Bsbnd Osbnd Ge, Sisbnd Osbnd Ge, Sisbnd Osbnd Si, and Pbsbnd Osbnd Ge. The energy band gaps were evaluated for the prepared glass samples based on Tauc plots of the UV-Vis spectra. The calculated values of the optical band gap decreased from 2.91 to 2.85 eV as the PbO content increased from x = 0.0 to x = 0.7. Furthermore, the Urbach energy was studied based on the UV-Vis results to confirm the disordered structure of the glass. The calculated densities of the glass samples (1.5835 g/cm3 to 3.9184 g/cm3) increased as the concentration of PbO increased, whereas they decreased with the molar volume.

  5. Activation cross sections of longer-lived radionuclides produced in germanium by alpha particle irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Takács, S., E-mail: stakacs@atomki.hu [Institute for Nuclear Research, Hungarian Academy of Sciences, Atomki, 4026 Debrecen (Hungary); Takács, M.P.; Ditrói, F. [Institute for Nuclear Research, Hungarian Academy of Sciences, Atomki, 4026 Debrecen (Hungary); Aikawa, M. [Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan); Haba, H.; Komori, Y. [Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198 (Japan)

    2016-09-15

    The cross sections of alpha particles induced nuclear reactions on natural germanium were investigated by using the standard stacked foil target technique, the activation method and high resolution gamma spectrometry. Targets with thickness of about 1 μm were prepared from natural Ge by vacuum evaporation onto 25 μm thick polyimide (Kapton) backing foils. Stacks were composed of Kapton-Ge-Ge-Kapton sandwich target foils and additional titanium monitor foils with nominal thickness of 11 μm to monitor the beam parameters using the {sup nat}Ti(α,x){sup 51}Cr reaction. The irradiations were done with E{sub α} = 20.7 and E{sub α} = 51.25 MeV, I{sub α} = 50 nA alpha particle beams for about 1 h. Direct or cumulative activation cross sections were determined for production of the {sup 72,73,75}Se, {sup 71,72,74,76,78}As, and {sup 69}Ge radionuclides. The obtained experimental cross sections were compared to the results of theoretical calculations taken from the TENDL data library based on the TALYS computer code. A comparison was made with available experimental data measured earlier. Thick target yields were deduced from the experimental cross sections and compared with the data published before.

  6. Two-electron germanium centers with a negative correlation energy in lead chalcogenides

    International Nuclear Information System (INIS)

    Terukov, E. I.; Marchenko, A. V.; Zaitseva, A. V.; Seregin, P. P.

    2007-01-01

    It is shown that the charge state of the 73 Ge antisite defect that arises in anionic sublattices of PbS, PbSe, and PbTe after radioactive transformation of 73 As does not depend on the position of the Fermi level, whereas the 73 Ge center in cationic sublattices of PbS and PbSe represents a two-electron donor with the negative correlation energy: the Moessbauer spectrum for the n-type samples corresponds to the neutral state of the donor center (Ge 2+ ), while this spectrum corresponds to the doubly ionized state (Ge 4+ ) of the center in the p-type samples. In partially compensated PbSe samples, a fast electron exchange between the neutral and ionized donor centers is realized. It is shown by the method of Moessbauer spectroscopy for the 119 Sn isotope that the germanium-related energy levels are located higher than the levels formed in the band gap of these semiconductors by the impurity tin atoms

  7. Stress evolution of Ge nanocrystals in dielectric matrices

    Science.gov (United States)

    Bahariqushchi, Rahim; Raciti, Rosario; Emre Kasapoğlu, Ahmet; Gür, Emre; Sezen, Meltem; Kalay, Eren; Mirabella, Salvatore; Aydinli, A.

    2018-05-01

    Germanium nanocrystals (Ge NCs) embedded in single and multilayer silicon oxide and silicon nitride matrices have been synthesized using plasma enhanced chemical vapor deposition followed by conventional furnace annealing or rapid thermal processing in N2 ambient. Compositions of the films were determined by Rutherford backscattering spectrometry and x-ray photoelectron spectroscopy. The formation of NCs under suitable process conditions was observed with high resolution transmission electron microscope micrographs and Raman spectroscopy. Stress measurements were done using Raman shifts of the Ge optical phonon line at 300.7 cm-1. The effect of the embedding matrix and annealing methods on Ge NC formation were investigated. In addition to Ge NCs in single layer samples, the stress on Ge NCs in multilayer samples was also analyzed. Multilayers of Ge NCs in a silicon nitride matrix separated by dielectric buffer layers to control the size and density of NCs were fabricated. Multilayers consisted of SiN y :Ge ultrathin films sandwiched between either SiO2 or Si3N4 by the proper choice of buffer material. We demonstrated that it is possible to tune the stress state of Ge NCs from compressive to tensile, a desirable property for optoelectronic applications. We also observed that there is a correlation between the stress and the crystallization threshold in which the compressive stress enhances the crystallization, while the tensile stress suppresses the process.

  8. Uranium enrichment

    International Nuclear Information System (INIS)

    Rae, H.K.; Melvin, J.G.

    1988-06-01

    Canada is the world's largest producer and exporter of uranium, most of which is enriched elsewhere for use as fuel in LWRs. The feasibility of a Canadian uranium-enrichment enterprise is therefore a perennial question. Recent developments in uranium-enrichment technology, and their likely impacts on separative work supply and demand, suggest an opportunity window for Canadian entry into this international market. The Canadian opportunity results from three particular impacts of the new technologies: 1) the bulk of the world's uranium-enrichment capacity is in gaseous diffusion plants which, because of their large requirements for electricity (more than 2000 kW·h per SWU), are vulnerable to competition from the new processes; 2) the decline in enrichment costs increases the economic incentive for the use of slightly-enriched uranium (SEU) fuel in CANDU reactors, thus creating a potential Canadian market; and 3) the new processes allow economic operation on a much smaller scale, which drastically reduces the investment required for market entry and is comparable with the potential Canadian SEU requirement. The opportunity is not open-ended. By the end of the century the enrichment supply industry will have adapted to the new processes and long-term customer/supplier relationships will have been established. In order to seize the opportunity, Canada must become a credible supplier during this century

  9. Effects of electronically neutral impurities on muonium in germanium

    International Nuclear Information System (INIS)

    Clawson, C.W.; Crowe, K.M.; Haller, E.E.; Rosenblum, S.S.; Brewer, J.H.

    1983-04-01

    Low-temperature measurements of muonium parameters in various germanium crystals have been performed. We have measured crystals with different levels of neutral impurities, with and without dislocations, and with different annealing histories. The most striking result is the apparent trapping of Mu by silicon impurities in germanium

  10. Inhibitive formation of nanocavities by introduction of Si atoms in Ge nanocrystals produced by ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Cai, R. S.; Shang, L.; Liu, X. H.; Zhang, Y. J. [The Cultivation Base for State Key Laboratory, Qingdao University, No. 308 Ningxia Road, Qingdao 266071 (China); Wang, Y. Q., E-mail: yqwang@qdu.edu.cn, E-mail: barba@emt.inrs.ca [The Cultivation Base for State Key Laboratory, Qingdao University, No. 308 Ningxia Road, Qingdao 266071 (China); College of Physics Science, Qingdao University, No. 308 Ningxia Road, Qingdao 266071 (China); Ross, G. G.; Barba, D., E-mail: yqwang@qdu.edu.cn, E-mail: barba@emt.inrs.ca [INRS-Énergie, Matériaux et Télécommunications, 1650 boulevard Lionel-Boulet, Varennes Québec J3X 1S2 (Canada)

    2014-05-28

    Germanium nanocrystals (Ge-nc) were successfully synthesized by co-implantation of Si and Ge ions into a SiO{sub 2} film thermally grown on (100) Si substrate and fused silica (pure SiO{sub 2}), respectively, followed by subsequent annealing at 1150 °C for 1 h. Transmission electron microscopy (TEM) examinations show that nanocavities only exist in the fused silica sample but not in the SiO{sub 2} film on a Si substrate. From the analysis of the high-resolution TEM images and electron energy-loss spectroscopy spectra, it is revealed that the absence of nanocavities in the SiO{sub 2} film/Si substrate is attributed to the presence of Si atoms inside the formed Ge-nc. Because the energy of Si-Ge bonds (301 kJ·mol{sup −1}) are greater than that of Ge-Ge bonds (264 kJ·mol{sup −1}), the introduction of the Si-Ge bonds inside the Ge-nc can inhibit the diffusion of Ge from the Ge-nc during the annealing process. However, for the fused silica sample, no crystalline Si-Ge bonds are detected within the Ge-nc, where strong Ge outdiffusion effects produce a great number of nanocavities. Our results can shed light on the formation mechanism of nanocavities and provide a good way to avoid nanocavities during the process of ion implantation.

  11. Measurement of the neutron-capture cross section of 76Ge and 74Ge below 15 MeV and its relevance to 0 νββ decay searches of 76Ge

    Science.gov (United States)

    Bhike, Megha; Fallin, B.; Krishichayan; Tornow, W.

    2015-02-01

    The neutron radiative-capture cross section of 76Ge was measured between 0.4 and 14.8 MeV using the activation technique. Germanium samples with the isotopic abundance of ∼ 86%76Ge and ∼ 14%74Ge used in the 0 νββ searches by the GERDA and Majorana Collaborations were irradiated with monoenergetic neutrons produced at eleven energies via the 3H (p , n)3He, 2H (d , n)3He and 3H (d , n)4He reactions. Previously, data existed only at thermal energies and at 14 MeV. As a by-product, capture cross-section data were also obtained for 74Ge at neutron energies below 8 MeV. Indium and gold foils were irradiated simultaneously for neutron fluence determination. High-resolution γ-ray spectroscopy was used to determine the γ-ray activity of the daughter nuclei of interest. For the 76Ge total capture cross section the present data are in good agreement with the TENDL-2013 model calculations and the ENDF/B-VII.1 evaluations, while for the 74Ge (n , γ)75Ge reaction, the present data are about a factor of two larger than predicted. It was found that the 74Ge (n , γ)75Ge yield in the High-Purity Germanium (HPGe) detectors used by the GERDA and Majorana Collaborations is only about a factor of two smaller than the 76Ge (n , γ)77Ge yield due to the larger cross section of the former reaction.

  12. Imaging capabilities of germanium gamma cameras

    International Nuclear Information System (INIS)

    Steidley, J.W.

    1977-01-01

    Quantitative methods of analysis based on the use of a computer simulation were developed and used to investigate the imaging capabilities of germanium gamma cameras. The main advantage of the computer simulation is that the inherent unknowns of clinical imaging procedures are removed from the investigation. The effects of patient scattered radiation were incorporated using a mathematical LSF model which was empirically developed and experimentally verified. Image modifying effects of patient motion, spatial distortions, and count rate capabilities were also included in the model. Spatial domain and frequency domain modeling techniques were developed and used in the simulation as required. The imaging capabilities of gamma cameras were assessed using low contrast lesion source distributions. The results showed that an improvement in energy resolution from 10% to 2% offers significant clinical advantages in terms of improved contrast, increased detectability, and reduced patient dose. The improvements are of greatest significance for small lesions at low contrast. The results of the computer simulation were also used to compare a design of a hypothetical germanium gamma camera with a state-of-the-art scintillation camera. The computer model performed a parametric analysis of the interrelated effects of inherent and technological limitations of gamma camera imaging. In particular, the trade-off between collimator resolution and collimator efficiency for detection of a given low contrast lesion was directly addressed. This trade-off is an inherent limitation of both gamma cameras. The image degrading effects of patient motion, camera spatial distortions, and low count rate were shown to modify the improvements due to better energy resolution. Thus, based on this research, the continued development of germanium cameras to the point of clinical demonstration is recommended

  13. In-situ gallium-doping for forming p{sup +} germanium-tin and application in germanium-tin p-i-n photodetector

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wei; Dong, Yuan; D' Costa, Vijay Richard; Yeo, Yee-Chia, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Vajandar, Saumitra; Lim, Sin Leng; Osipowicz, Thomas; Tok, Eng Soon [Department of Physics and Yale-NUS College, National University of Singapore, Singapore 117551 (Singapore)

    2016-04-21

    The in-situ Ga doping technique was used to form heavily p-type doped germanium-tin (Ge{sub 1−x}Sn{sub x}) layers by molecular beam epitaxy, avoiding issues such as Sn precipitation and surface segregation at high annealing temperatures that are associated with the alternative implant and anneal approach. In this way, an electrically active Ga concentration of up to ∼3.2 × 10{sup 20 }cm{sup −3} can be realized for Ge{sub 1−x}Sn{sub x}. The impacts of varying the Ga concentration on the crystalline quality and the mobility of p-type Ge{sub 1−x}Sn{sub x} were investigated. High crystalline quality Ge{sub 0.915}Sn{sub 0.085} can be realized with an active Ga concentration of up to ∼1.2 × 10{sup 20 }cm{sup −3}. More than 98% of the Sn atoms are located on substitutional lattice sites, although the substitutionality of Sn in p-type Ge{sub 1−x}Sn{sub x} decreases with an increasing Ga concentration. When the Ga concentration introduced is higher than 3.2 × 10{sup 20 }cm{sup −3}, excess Ga atoms cannot be substitutionally incorporated, and segregation of Ga and Sn towards the surface during growth is observed. The in-situ Ga-doped Ge{sub 0.915}Sn{sub 0.085} epitaxy was integrated in a Ge{sub 0.915}Sn{sub 0.085}-on-Si p-i-n (PIN) photodiode fabrication process, and well-behaved Ge{sub 0.915}Sn{sub 0.085}/Si PIN junction characteristics were obtained. A large forward-bias current to reverse bias current ratio of 6 × 10{sup 4} and a low reverse current (dark current) of 0.24 μA were achieved at V{sub bias} = −1 V.

  14. Uranium enrichment

    International Nuclear Information System (INIS)

    Mohrhauer, H.

    1982-01-01

    The separation of uranium isotopes in order to enrich the fuel for light water reactors with the light isotope U-235 is an important part of the nuclear fuel cycle. After the basic principals of isotope separation the gaseous diffusion and the centrifuge process are explained. Both these techniques are employed on an industrial scale. In addition a short review is given on other enrichment techniques which have been demonstrated at least on a laboratory scale. After some remarks on the present situation on the enrichment market the progress in the development and the industrial exploitation of the gas centrifuge process by the trinational Urenco-Centec organisation is presented. (orig.)

  15. Array of germanium detectors for nuclear safeguards

    International Nuclear Information System (INIS)

    Moss, C.E.; Bernard, W.; Dowdy, E.J.; Garcia, C.; Lucas, M.C.; Pratt, J.C.

    1983-01-01

    Our gamma-ray spectrometer system, designed for field use, offers high efficiency and high resolution for safeguards applications. The system consists of three 40% high-purity germanium detectors and a LeCroy 3500 data-acquisition system that calculates a composite spectrum for the three detectors. The LeCroy 3500 mainframe can be operated remotely from the detector array with control exercised through moderns and the telephone system. System performance with a mixed source of 125 Sb, 154 Eu, and 155 Eu confirms the expected efficiency of 120% with an overall resolution that is between the resolution of the best detector and that of the worst

  16. Alleviation of Fermi level pinning at metal/n-Ge interface with lattice-matched Si x Ge1‑ x ‑ y Sn y ternary alloy interlayer on Ge

    Science.gov (United States)

    Suzuki, Akihiro; Nakatsuka, Osamu; Sakashita, Mitsuo; Zaima, Shigeaki

    2018-06-01

    The impact of a silicon germanium tin (Si x Ge1‑ x ‑ y Sn y ) ternary alloy interlayer on the Schottky barrier height (SBH) of metal/Ge contacts with various metal work functions has been investigated. Lattice matching at the Si x Ge1‑ x ‑ y Sn y /Ge heterointerface is a key factor for controlling Fermi level pinning (FLP) at the metal/Ge interface. The Si x Ge1‑ x ‑ y Sn y ternary alloy interlayer having a small lattice mismatch with the Ge substrate can alleviate FLP at the metal/Ge interface significantly. A Si0.11Ge0.86Sn0.03 interlayer increases the slope parameter for the work function dependence of the SBH to 0.4. An ohmic behavior with an SBH below 0.15 eV can be obtained with Zr and Al/Si0.11Ge0.86Sn0.03/n-Ge contacts at room temperature.

  17. Tungsten silicide contacts to polycrystalline silicon and silicon-germanium alloys

    International Nuclear Information System (INIS)

    Srinivasan, G.; Bain, M.F.; Bhattacharyya, S.; Baine, P.; Armstrong, B.M.; Gamble, H.S.; McNeill, D.W.

    2004-01-01

    Silicon-germanium alloy layers will be employed in the source-drain engineering of future MOS transistors. The use of this technology offers advantages in reducing series resistance and decreasing junction depth resulting in reduction in punch-through and SCE problems. The contact resistance of metal or metal silicides to the raised source-drain material is a serious issue at sub-micron dimensions and must be minimised. In this work, tungsten silicide produced by chemical vapour deposition has been investigated as a contact metallization scheme to both boron and phosphorus doped polycrystalline Si 1- x Ge x , with 0 ≤x ≤ 0.3. Cross bridge Kelvin resistor (CKBR) structures were fabricated incorporating CVD WSi 2 and polycrystalline SiGe. Tungsten silicide contacts to control polysilicon CKBR structures have been shown to be of high quality with specific contact resistance ρ c values 3 x 10 -7 ohm cm 2 and 6 x 10 -7 ohm cm 2 obtained to boron and phosphorus implanted samples respectively. The SiGe CKBR structures show that the inclusion of Ge yields a reduction in ρ c for both dopant types. The boron doped SiGe exhibits a reduction in ρ c from 3 x 10 -7 to 5 x 10 -8 ohm cm 2 as Ge fraction is increased from 0 to 0.3. The reduction in ρ c has been shown to be due to (i) the lowering of the tungsten silicide Schottky barrier height to p-type SiGe resulting from the energy band gap reduction, and (ii) increased activation of the implanted boron with increased Ge fraction. The phosphorus implanted samples show less sensitivity of ρ c to Ge fraction with a lowest value in this work of 3 x 10 -7 ohm cm 2 for a Ge fraction of 0.3. The reduction in specific contact resistance to the phosphorus implanted samples has been shown to be due to increased dopant activation alone

  18. Nuclear energy outlook: a GE perspective

    International Nuclear Information System (INIS)

    Fuller, J.

    2006-01-01

    Full text: Full text: As one of the world's leading suppliers of power generation and energy delivery technologies, GE Energy provides comprehensive solutions for coal, oil, natural gas and nuclear energy; renewable resources such as wind, solar and biogas, along with other alternative fuels. With the ever increasing demand for energy and pressures to decrease greenhouse gas emissions, global trends indicate a move towards building more base line nuclear generation capacity. As a reliable, cost-competitive option for commercial power generation, nuclear energy also addresses many of the issues the world faces when it comes to the environment. Since developing nuclear reactor technology in the 1950s, GE's Boiling Water Reactor (BWR) technology accounts for more than 90 operating plants in the world today. Building on that success, GE's ABWR design is now the first and only Generation 111 nuclear reactor in operation today. This advanced reactor technology, coupled with current construction experience and a qualified global supply chain, make ESBWR, GE's Generation III+ reactor design, an attractive option for owners considering adding nuclear generation capacity. In pursuit of new technologies, GE has teamed with Silex to develop, commercialize and license third generation laser enrichment technology. By acquiring the exclusive rights to develop and commercialize this technology, GE is positioned to support the anticipated global demands for enriched uranium. At GE, we are continuing to develop imaginative ideas and investing in products that are cost effective, increase productivity, limit greenhouse gas emissions, and improve safety and security for our customers

  19. Impact of negative capacitance effect on Germanium Double Gate pFET for enhanced immunity to interface trap charges

    Science.gov (United States)

    Bansal, Monika; Kaur, Harsupreet

    2018-05-01

    In this work, a comprehensive drain current model has been developed for long channel Negative Capacitance Germanium Double Gate p-type Field Effect Transistor (NCGe-DG-pFET) by using 1-D Poisson's equation and Landau-Khalatnikov equation. The model takes into account interface trap charges and by using the derived model various parameters such as surface potential, gain, gate capacitance, subthreshold swing, drain current, transconductance, output conductance and Ion/Ioff ratio have been obtained and it is demonstrated that by incorporating ferroelectric material as gate insulator with Ge-channel, subthreshold swing values less than 60 mV/dec can be achieved along with improved gate controllability and current drivability. Further, to critically analyze the advantages offered by NCGe-DG-pFET, a detailed comparison has been done with Germanium Double Gate p-type Field Effect Transistor (Ge-DG-pFET) and it is shown that NCGe-DG-pFET exhibits high gain, enhanced transport efficiency in channel, very less or negligible degradation in device characteristics due to interface trap charges as compared to Ge-DG-pFET. The analytical results so obtained show good agreement with simulated results obtained from Silvaco ATLAS TCAD tool.

  20. Production and separation of no-carrier-added 73As and 75Se from 7Li irradiated germanium oxide target

    International Nuclear Information System (INIS)

    Mandal, A.; Lahiri, S.

    2012-01-01

    This work reports for the first time 7 Li-induced accelerator based production of 71,72,73,74 As, 75,76,77 Br and 73,75 Se radionuclides in their no-carrier-added (nca) state. After the decay of all short-lived radionuclides 75 Se and 73 As were only existing radionuclides in germanium oxide target, which were subsequently separated by liquid-liquid extraction (LLX) using trioctylamine (TOA) dissolved in cyclohexane as liquid ion exchanger. The presence of stable germanium in various fractions was examined by Inductively Coupled Plasma Optical Spectrometry (ICP-OES). At 0.1 M TOA and 10 M HCl concentration, 75 Se and stable Ge were extracted into the organic phase leaving 73 As in the aqueous phase. The bulk Ge was stripped back to the aqueous phase by 1 M NaOH, keeping 75 Se in the organic phase. Therefore complete separation between 73 As, 75 Se and bulk Ge was achieved. (orig.)

  1. Studies of the chemical behavior of carrier-free 68Ge. Pt. 1

    International Nuclear Information System (INIS)

    Mirzadeh, S.; Kahn, M.; Grant, P.M.; O'Brien, H.A. Jr.

    1981-01-01

    The diagnostic utilization of the 68 Ge- 68 Ga system in nuclear medicine stimulated the development of a rapid and efficient method for the purification of carrier-free 68 Ge. A standard procedure for the separation of macroscopic quantities for germanium from numerous other elements involves the distillation of Ge(IV) from HCl solution. The applicability of this method for the purification of carrier-free 68 Ge was studied, and it was found that 68 Ge quantitatively and conveniently distills from azetropic HCl. The distillation of 68 Ge from LiCl-HClO 4 , HCl-LiCl, and HCl-HClO 4 systems was also investigated. (orig.) [de

  2. High-purity germanium crystal growing

    International Nuclear Information System (INIS)

    Hansen, W.L.; Haller, E.E.

    1982-10-01

    The germanium crystals used for the fabrication of nuclear radiation detectors are required to have a purity and crystalline perfection which is unsurpassed by any other solid material. These crystals should not have a net electrically active impurity concentration greater than 10 10 cm - 3 and be essentially free of charge trapping defects. Such perfect crystals of germanium can be grown only because of the highly favorable chemical and physical properties of this element. However, ten years of laboratory scale and commercial experience has still not made the production of such crystals routine. The origin and control of many impurities and electrically active defect complexes is now fairly well understood but regular production is often interrupted for long periods due to the difficulty of achieving the required high purity or to charge trapping in detectors made from crystals seemingly grown under the required conditions. The compromises involved in the selection of zone refining and crystal grower parts and ambients is discussed and the difficulty in controlling the purity of key elements in the process is emphasized. The consequences of growing in a hydrogen ambient are discussed in detail and it is shown how complexes of neutral defects produce electrically active centers

  3. Electromechanically cooled germanium radiation detector system

    International Nuclear Information System (INIS)

    Lavietes, Anthony D.; Joseph Mauger, G.; Anderson, Eric H.

    1999-01-01

    We have successfully developed and fielded an electromechanically cooled germanium radiation detector (EMC-HPGe) at Lawrence Livermore National Laboratory (LLNL). This detector system was designed to provide optimum energy resolution, long lifetime, and extremely reliable operation for unattended and portable applications. For most analytical applications, high purity germanium (HPGe) detectors are the standard detectors of choice, providing an unsurpassed combination of high energy resolution performance and exceptional detection efficiency. Logistical difficulties associated with providing the required liquid nitrogen (LN) for cooling is the primary reason that these systems are found mainly in laboratories. The EMC-HPGe detector system described in this paper successfully provides HPGe detector performance in a portable instrument that allows for isotopic analysis in the field. It incorporates a unique active vibration control system that allows the use of a Sunpower Stirling cycle cryocooler unit without significant spectral degradation from microphonics. All standard isotopic analysis codes, including MGA and MGA++, GAMANL, GRPANL and MGAU, typically used with HPGe detectors can be used with this system with excellent results. Several national and international Safeguards organisations including the International Atomic Energy Agency (IAEA) and U.S. Department of Energy (DOE) have expressed interest in this system. The detector was combined with custom software and demonstrated as a rapid Field Radiometric Identification System (FRIS) for the U.S. Customs Service . The European Communities' Safeguards Directorate (EURATOM) is field-testing the first Safeguards prototype in their applications. The EMC-HPGe detector system design, recent applications, and results will be highlighted

  4. Assessing the potential roles of silicon and germanium phthalocyanines in planar heterojunction organic photovoltaic devices and how pentafluoro phenoxylation can enhance π-π interactions and device performance.

    Science.gov (United States)

    Lessard, Benoît H; White, Robin T; Al-Amar, Mohammad; Plint, Trevor; Castrucci, Jeffrey S; Josey, David S; Lu, Zheng-Hong; Bender, Timothy P

    2015-03-11

    In this study, we have assessed the potential application of dichloro silicon phthalocyanine (Cl2-SiPc) and dichloro germanium phthalocyanine (Cl2-GePc) in modern planar heterojunction organic photovoltaic (PHJ OPV) devices. We have determined that Cl2-SiPc can act as an electron donating material when paired with C60 and that Cl2-SiPc or Cl2-GePc can also act as an electron acceptor material when paired with pentacene. These two materials enabled the harvesting of triplet energy resulting from the singlet fission process in pentacene. However, contributions to the generation of photocurrent were observed for Cl2-SiPc with no evidence of photocurrent contribution from Cl2-GePc. The result of our initial assessment established the potential for the application of SiPc and GePc in PHJ OPV devices. Thereafter, bis(pentafluoro phenoxy) silicon phthalocyanine (F10-SiPc) and bis(pentafluoro phenoxy) germanium phthalocyanine (F10-GePc) were synthesized and characterized. During thermal processing, it was discovered that F10-SiPc and F10-GePc underwent a reaction forming small amounts of difluoro SiPc (F2-SiPc) and difluoro GePc (F2-GePc). This undesirable reaction could be circumvented for F10-SiPc but not for F10-GePc. Using single crystal X-ray diffraction, it was determined that F10-SiPc has significantly enhanced π-π interactions compared with that of Cl2-SiPc, which had little to none. Unoptimized PHJ OPV devices based on F10-SiPc were fabricated and directly compared to those constructed from Cl2-SiPc, and in all cases, PHJ OPV devices based on F10-SiPc had significantly improved device characteristics compared to Cl2-SiPc.

  5. Steering of sub-GeV electrons by ultrashort Si and Ge bent crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sytov, A.I. [Ferrara Univ. (Italy). Dipt. di Fisica e Scienze della Terra; Belarusian State Univ., Minsk (Belarus). Inst. for Nuclear Problems; INFN Sezione di Ferrara (Italy); Bandiera, L.; Mazzolari, A.; Bagli, E.; Germogli, G.; Guidi, V.; Romagnoni, M. [Ferrara Univ. (Italy). Dipt. di Fisica e Scienze della Terra; INFN Sezione di Ferrara (Italy); De Salvador, D.; Carturan, S.; Maggioni, G. [INFN, Laboratori Nazionali di Legnaro (Italy); Padova Univ. (Italy). Dipt. di Fisica; Berra, A.; Prest, M. [Univ. dell' Insubria, Como (Italy); INFN, Sezione di Milano Bicocca, Milan (Italy); Durighello, C. [Ferrara Univ. (Italy). Dipt. di Fisica e Scienze della Terra; INFN, Laboratori Nazionali di Legnaro (Italy); Padova Univ. (Italy). Dipt. di Fisica; INFN Sezione di Ferrara (Italy); Klag, P.; Lauth, W. [Mainz Univ. (Germany). Inst. fuer Kernphysik; Tikhomirov, V.V. [Belarusian State Univ., Minsk (Belarus). Inst. for Nuclear Problems; Vallazza, E. [INFN, Sezione di Trieste (Italy)

    2017-12-15

    We report the observation of the steering of 855 MeV electrons by bent silicon and germanium crystals at the MAinzer MIkrotron. Crystals with 15 μm of length, bent along (111) planes, were exploited to investigate orientational coherent effects. By using a piezo-actuated mechanical holder, which allowed to remotely change the crystal curvature, it was possible to study the steering capability of planar channeling and volume reflection vs. the curvature radius and the atomic number, Z. For silicon, the channeling efficiency exceeds 35%, a record for negatively charged particles. This was possible due to the realization of a crystal with a thickness of the order of the dechanneling length. On the other hand, for germanium the efficiency is slightly below 10% due to the stronger contribution of multiple scattering for a higher-Z material. Nevertheless this is the first evidence of negative beam steering by planar channeling in a Ge crystal. Having determined for the first time the dechanneling length, one may design a Ge crystal based on such knowledge providing nearly the same channeling efficiency of silicon. The presented results are relevant for crystal-based beam manipulation as well as for the generation of e.m. radiation in bent and periodically bent crystals. (orig.)

  6. Steering of Sub-GeV electrons by ultrashort Si and Ge bent crystals

    Science.gov (United States)

    Sytov, A. I.; Bandiera, L.; De Salvador, D.; Mazzolari, A.; Bagli, E.; Berra, A.; Carturan, S.; Durighello, C.; Germogli, G.; Guidi, V.; Klag, P.; Lauth, W.; Maggioni, G.; Prest, M.; Romagnoni, M.; Tikhomirov, V. V.; Vallazza, E.

    2017-12-01

    We report the observation of the steering of 855 MeV electrons by bent silicon and germanium crystals at the MAinzer MIkrotron. Crystals with 15 μ m of length, bent along (111) planes, were exploited to investigate orientational coherent effects. By using a piezo-actuated mechanical holder, which allowed to remotely change the crystal curvature, it was possible to study the steering capability of planar channeling and volume reflection vs. the curvature radius and the atomic number, Z. For silicon, the channeling efficiency exceeds 35%, a record for negatively charged particles. This was possible due to the realization of a crystal with a thickness of the order of the dechanneling length. On the other hand, for germanium the efficiency is slightly below 10% due to the stronger contribution of multiple scattering for a higher-Z material. Nevertheless this is the first evidence of negative beam steering by planar channeling in a Ge crystal. Having determined for the first time the dechanneling length, one may design a Ge crystal based on such knowledge providing nearly the same channeling efficiency of silicon. The presented results are relevant for crystal-based beam manipulation as well as for the generation of e.m. radiation in bent and periodically bent crystals.

  7. Influence of the Localization of Ge Atoms within the Si(001(4 × 2 Surface Layer on Semicore One-Electron States

    Directory of Open Access Journals (Sweden)

    Olha I. Tkachuk

    2016-03-01

    Full Text Available Adsorption complexes of germanium on the reconstructed Si(001(4 × 2 surface have been simulated by the Si96Ge2Н84 cluster. For Ge atoms located on the surface layer, DFT calculations (B3LYP/6-31G** of their 3d semicore-level energies have shown a clear-cut correlation between the 3d5/2 chemical shifts and mutual arrangement of Ge atoms. Such a shift is positive when only one Ge atom penetrates into the crystalline substrate, while being negative for both penetrating Ge atoms. We interpret these results in terms of the charge distribution in clusters under consideration.

  8. Characterization of the liquid argon veto of the GERDA experiment and its application for the measurement of the "7"6Ge half-life

    International Nuclear Information System (INIS)

    Wegmann, Anne Christin

    2017-01-01

    The search for neutrinoless double-beta decay (0νββ) is one of the most active fields in modern particle physics as the observation of this process would prove lepton number violation and imply new physics beyond the Standard Model of particle physics. The GERDA experiment searches for this decay by operating bare Germanium detectors, enriched in the ββ isotope "7"6Ge, in liquid argon. For the first time, a ββ-experiment combines the excellent properties of semiconductor Germanium detectors with an active background suppression technique based on the simultaneous detection of liquid argon scintillation light by photomultiplier tubes and silicon photomultipliers coupled to scintillating fibers (LAr veto). The LAr veto has been successfully operated during the first six months of Phase II of the experiment and yielded - in combination with a Germanium detector pulse shape discrimination technique - a background index of (0.7"+"1"."1_-_0_._5).10"-"3 ((cts)/(kg.keV.yr)). With an ultimate exposure of 100 kg.yr this will allow for a 0νββ-decay half-life sensitivity of the Gerda Phase II experiment of 10"2"6 yr. Double-beta decay under the emission of two neutrinos (2νββ) is a second-order process but which is allowed by the Standard Model. The excellent background reduction of the LAr veto results in an unprecedented signal-to-background ratio of 30:1 in the energy region dominated by 2νββ-decay of "7"6Ge. The remaining background after LAr veto is estimated using the suppression factor from calibration source measurements and results in a measurement of T"2"ν_1_/_2=(1.98±0.02(stat)±0.05(syst)).10"2"1 yr and T_1_/_2"2"ν=(1.92 ±0.02(stat)±0.11(syst)).10"2"1 yr based on two different detector designs and give uncertainties on the detector parameters but both with improved systematic uncertainties in comparison to earlier measurements.

  9. Characterization of the liquid argon veto of the GERDA experiment and its application for the measurement of the {sup 76}Ge half-life

    Energy Technology Data Exchange (ETDEWEB)

    Wegmann, Anne Christin

    2017-01-18

    The search for neutrinoless double-beta decay (0νββ) is one of the most active fields in modern particle physics as the observation of this process would prove lepton number violation and imply new physics beyond the Standard Model of particle physics. The GERDA experiment searches for this decay by operating bare Germanium detectors, enriched in the ββ isotope {sup 76}Ge, in liquid argon. For the first time, a ββ-experiment combines the excellent properties of semiconductor Germanium detectors with an active background suppression technique based on the simultaneous detection of liquid argon scintillation light by photomultiplier tubes and silicon photomultipliers coupled to scintillating fibers (LAr veto). The LAr veto has been successfully operated during the first six months of Phase II of the experiment and yielded - in combination with a Germanium detector pulse shape discrimination technique - a background index of (0.7{sup +1.1}{sub -0.5}).10{sup -3} ((cts)/(kg.keV.yr)). With an ultimate exposure of 100 kg.yr this will allow for a 0νββ-decay half-life sensitivity of the Gerda Phase II experiment of 10{sup 26} yr. Double-beta decay under the emission of two neutrinos (2νββ) is a second-order process but which is allowed by the Standard Model. The excellent background reduction of the LAr veto results in an unprecedented signal-to-background ratio of 30:1 in the energy region dominated by 2νββ-decay of {sup 76}Ge. The remaining background after LAr veto is estimated using the suppression factor from calibration source measurements and results in a measurement of T{sup 2ν}{sub 1/2}=(1.98±0.02(stat)±0.05(syst)).10{sup 21} yr and T{sub 1/2}{sup 2ν}=(1.92 ±0.02(stat)±0.11(syst)).10{sup 21} yr based on two different detector designs and give uncertainties on the detector parameters but both with improved systematic uncertainties in comparison to earlier measurements.

  10. The establishment of bed type germanium-based whole body counters

    International Nuclear Information System (INIS)

    Chen, M.C.; Sun, C.L.; Yeh, W.W.

    1996-01-01

    A coaxial germanium detector was installed in a shadow-shield counter for the in-vivo measurement of γ emitters in the body. It is divided into two subparts, automatic liquid nitrogen transfer system and the Ge-based counting system. The automatic liquid nitrogen transfer system and a complete gamma spectroscopy software package were manufactured by EG and G ORTEC company. Some experiments were finished to get the optimum three setting parameters for how to operate the auto liquid nitrogen transfer system in good conditions. The filling interval should be setting at eight hours, the filling time should be setting at ten minutes, and the pressure of dewar should operate in a range from 14 to 26 PSI. The RMC-II phantom that is designed by Canberra company is used as standard man for all kinds of calibrations. The detector has resolutions that are less than 2.5 keV with an average of 1.87 keV for the 60 Co 1.33-MeV γ-ray peak. The efficiency value of thyroid geometry for four different organs is highest in the phantom. The resolution of the Germanium detector for measuring radioactivity in the body that is better than the sodium iodide detector is used to measure the internal depositions of radionuclide mixtures. So, the advantage of the germanium counter can just compensate the disadvantage of the NaI(TI) detector. The qualitative and quantitative analysis for whole body counting can keep in the best conditions if both whole body counters are operated at the same time for routine measurement purpose in the laboratory

  11. Effects of flexible substrate thickness on Al-induced crystallization of amorphous Ge thin films

    Energy Technology Data Exchange (ETDEWEB)

    Oya, Naoki [Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Toko, Kaoru, E-mail: toko@bk.tsukuba.ac.jp [Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Saitoh, Noriyuki; Yoshizawa, Noriko [Electron Microscope Facility, TIA, AIST, 16-1 Onogawa, Tsukuba 305-8569 (Japan); Suemasu, Takashi [Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan)

    2015-05-29

    Amorphous germanium (a-Ge) thin films were directly crystallized on flexible plastic substrates at 325 °C using Al-induced crystallization. The thickness of the plastic substrate strongly influenced the crystal quality of the resulting polycrystalline Ge layers. Using a thicker substrate lowered the stress on the a-Ge layer during annealing, which increased the grain size and fraction of (111)-oriented grains within the Ge layer. Employing a 125-μm-thick substrate led to 95% (111)-oriented Ge with grains having an average size of 100 μm. Transmission electron microscopy demonstrated that the Ge grains had a low-defect density. Production of high-quality Ge films on plastic substrates allows for the possibility for developing Ge-based electronic and optical devices on inexpensive flexible substrates. - Highlights: • Polycrystalline Ge thin films are directly formed on flexible plastic substrates. • Al-induced crystallization allows the low-temperature growth (325 °C) of amorphous Ge. • The substrate bending during annealing strongly influences the crystal quality of poly-Ge. • A thick substrate (125 μm) leads to 95% (111)-oriented Ge with grains 100 μm in size.

  12. Assessment of Bioavailable Concentrations of Germanium and Rare Earth Elements in the Rhizosphere of White Lupin (Lupinus albus L.)

    Science.gov (United States)

    Wiche, Oliver; Fischer, Ronny; Moschner, Christin; Székely, Balázs

    2015-04-01

    Concentrations of Germanium (Ge) and Rare Earth Elements in soils are estimated at 1.5 mg kg -1 (Ge), 25 mg kg -1 (La) and 20 mg kg -1 (Nd), which are only roughly smaller than concentrations of Pb and Zn. Germanium and rare earth elements are thus not rare but widely dispersed in soils and therefore up to date, only a few minable deposits are available. An environmental friendly and cost-effective way for Ge and rare earth element production could be phytomining. However, the most challenging part of a phytomining of these elements is to increase bioavailable concentrations of the elements in soils. Recent studies show, that mixed cultures with white lupine or other species with a high potential to mobilize trace metals in their rhizosphere due to an acidification of the soil and release of organic acids in the root zone could be a promising tool for phytomining. Complexation of Ge and rare earth elements by organic acids might play a key role in controlling bioavailability to plants as re-adsorption on soil particles and precipitation is prevented and thus, concentrations in the root zone of white lupine increase. This may also allow the complexes to diffuse along a concentration gradient to the roots of mixed culture growing species leading to enhanced plant uptake. However, to optimize mixed cultures it would be interesting to know to which extend mobilization of trace metals is dependent from chemical speciation of elements in soil due to the interspecific interaction of roots. A method for the identification of complexes of germanium and rare earth elements with organic acids, predominantly citric acid in the rhizosphere of white lupine was developed and successfully tested. The method is based on coupling of liquid chromatography with ICP-MS using a zic-philic column (SeQuant). As a preliminary result, we were able to show that complexes of germanium with citric acid exist in the rhizosphere of white lupin, what may contribute to the bioavailability of this

  13. Spectra of germanium and selenium in the 50-350 A region from the PLT tokamak plasma

    International Nuclear Information System (INIS)

    Stratton, B.C.; Hodge, W.L.; Moos, H.W.; Schwob, J.L.; Suckewer, S.; Finkenthal, M.; Cohen, S.

    1983-03-01

    Spectra of germanium and selenium injected into the PLT tokamak plasma were observed in the 50 to 350 A region for GeXIV-XXV (KI to OI-like) and SeXVI-XXIV (KI to NaI-like). A number of 3p/sup k/-3p/sup k-1/3d transitions predicted by isoelectronic sequence extrapolation have been identified. Also, previously identified lines from ions in the AlI to OI-like and KI-like isoelectronic sequences have been observed in the tokamak plasma

  14. Nanoscale resonant-cavity-enhanced germanium photodetectors with lithographically defined spectral response for improved performance at telecommunications wavelengths.

    Science.gov (United States)

    Balram, Krishna C; Audet, Ross M; Miller, David A B

    2013-04-22

    We demonstrate the use of a subwavelength planar metal-dielectric resonant cavity to enhance the absorption of germanium photodetectors at wavelengths beyond the material's direct absorption edge, enabling high responsivity across the entire telecommunications C and L bands. The resonant wavelength of the detectors can be tuned linearly by varying the width of the Ge fin, allowing multiple detectors, each resonant at a different wavelength, to be fabricated in a single-step process. This approach is promising for the development of CMOS-compatible devices suitable for integrated, high-speed, and energy-efficient photodetection at telecommunications wavelengths.

  15. Euromet action 428: transfer of ge detectors efficiency calibration from point source geometry to other geometries; Action euromet 428: transfert de l'etalonnage en rendement de detecteurs au germanium pour une source ponctuelle vers d'autres geometries

    Energy Technology Data Exchange (ETDEWEB)

    Lepy, M.Ch

    2000-07-01

    The EUROMET project 428 examines efficiency transfer computation for Ge gamma-ray spectrometers when the efficiency is known for a reference point source geometry in the 60 keV to 2 MeV energy range. For this, different methods are used, such as Monte Carlo simulation or semi-empirical computation. The exercise compares the application of these methods to the same selected experimental cases to determine the usage limitations versus the requested accuracy. For carefully examining these results and trying to derive information for improving the computation codes, this study was limited to a few simple cases, from an experimental efficiency calibration for point source at 10-cm source-to-detector distance. The first part concerns the simplest case of geometry transfer, i.e., using point sources for 3 source-to-detector distances: 2,5 and 20 cm; the second part deals with transfer from point source geometry to cylindrical geometry with three different matrices. The general results show that the deviations between the computed results and the measured efficiencies are for the most part within 10%. The quality of the results is rather inhomogeneous and shows that these codes cannot be used directly for metrological purposes. However, most of them are operational for routine measurements when efficiency uncertainties of 5-10% can be sufficient. (author)

  16. Silicon Germanium Quantum Well Solar Cell

    Data.gov (United States)

    National Aeronautics and Space Administration — A single crystal SiGe has enormous potentials for high performance chips and solar cells. This project seeks to fabricate a rudimentary but 1st cut quantum-well...

  17. Dependence of magnetic properties on ferromagnetic layer thickness in trilayer Co/Ge/Co films with granular semiconducting spacer

    International Nuclear Information System (INIS)

    Patrin, G.S.; Lee, C.-G.; Turpanov, I.A.; Zharkov, S.M.; Velikanov, D.A.; Maltsev, V.K.; Li, L.A.; Lantsev, V.V.

    2006-01-01

    We have investigated the magnetic properties of trilayer films of Co-Ge-Co. At a fixed thickness of germanium of 3.5 nm, the formation and distribution of metastable amorphous and cubic phases depends on the thickness of the ferromagnetic layer. The portion of the stable hexagonal phase is affected, too. Possible mechanisms for forming the observed magnetic structure are discussed

  18. Structural and optical characterization of self-assembled Ge nanocrystal layers grown by plasma-enhanced chemical vapor deposition

    NARCIS (Netherlands)

    Saeed, S.; Buters, F.; Dohnalova, K.; Wosinski, L.; Gregorkiewicz, T.

    2014-01-01

    We present a structural and optical study of solid-state dispersions of Ge nanocrystals prepared by plasma-enhanced chemical vapor deposition. Structural analysis shows the presence of nanocrystalline germanium inclusions embedded in an amorphous matrix of Si-rich SiO2. Optical characterization

  19. Determination of the laterally homogeneous barrier height of palladium Schottky barrier diodes on n-Ge (111)

    CSIR Research Space (South Africa)

    Chawanda, A

    2011-05-01

    Full Text Available The authors have studied the experimental linear relationship between barrier heights and ideality factors for palladium (Pd) on bulk-grown (1 1 1) Sb-doped n-type germanium (Ge) metal-semiconductor structures with a doping density of about 2...

  20. Fast neutron damage in germanium detectors

    International Nuclear Information System (INIS)

    Kraner, H.W.

    1979-10-01

    The effects of fast neutron radiation damage on the performance of both Ge(Li) and Ge(HP) detectors have been studied during the past decade and will be summarized. A review of the interaction processes leading to the defect structures causing trapping will be made. The neutron energy dependence of observable damage effects will be considered in terms of interaction and defect production cross sections

  1. High-Performance Silicon-Germanium-Based Thermoelectric Modules for Gas Exhaust Energy Scavenging

    Science.gov (United States)

    Romanjek, K.; Vesin, S.; Aixala, L.; Baffie, T.; Bernard-Granger, G.; Dufourcq, J.

    2015-06-01

    Some of the energy used in transportation and industry is lost as heat, often at high-temperatures, during conversion processes. Thermoelectricity enables direct conversion of heat into electricity, and is an alternative to the waste-heat-recovery technology currently used, for example turbines and other types of thermodynamic cycling. The performance of thermoelectric (TE) materials and modules has improved continuously in recent decades. In the high-temperature range ( T hot side > 500°C), silicon-germanium (SiGe) alloys are among the best TE materials reported in the literature. These materials are based on non-toxic elements. The Thermoelectrics Laboratory at CEA (Commissariat à l'Energie Atomique et aux Energies Alternatives) has synthesized n and p-type SiGe pellets, manufactured TE modules, and integrated these into thermoelectric generators (TEG) which were tested on a dedicated bench with hot air as the source of heat. SiGe TE samples of diameter 60 mm were created by spark-plasma sintering. For n-type SiGe doped with phosphorus the peak thermoelectric figure of merit reached ZT = 1.0 at 700°C whereas for p-type SiGe doped with boron the peak was ZT = 0.75 at 700°C. Thus, state-of-the-art conversion efficiency was obtained while also achieving higher production throughput capacity than for competing processes. A standard deviation high reproducibility. A silver-paste-based brazing technique was used to assemble the TE elements into modules. This assembly technique afforded low and repeatable electrical contact resistance (high temperatures (up to 600°C), and thirty 20 mm × 20 mm TE modules were produced and tested. The results revealed the performance was reproducible, with power output reaching 1.9 ± 0.2 W for a 370 degree temperature difference. When the temperature difference was increased to 500°C, electrical power output increased to >3.6 W. An air-water heat exchanger was developed and 30 TE modules were clamped and connected electrically

  2. Synthesis and superconducting properties of niobium germanium

    International Nuclear Information System (INIS)

    Kihlstrom, K.E.

    1982-01-01

    By carefully controlling temperature homogeneity during preparation of the Nb 3 Ge samples, homogeneous films have been prepared of high-T/sub c/Nb 3 Ge. Homogeneity is demonstrated by a sharp transition width (ΔT/sub c/ 6 amps/cm 2 which are the highest ever reported for any material at this temperature. The successful film synthesis has made it possible to study the superconducting properties of Nb 3 Ge. High quality A15 NbGe/(SiO/sub x/)/Pb tunnel juctions on electron beam codeposited oxygen-doped Nb 3 Ge have been fabricated. 2Δ/(k/sub B/T/sub c/ rises from the BCS limit in Ge-poor samples to become strong coupled (2Δk/sub B/T/sub c/ approx. 4.35) as stoichiometry is approached. The electron-phonon spectral function α 2 F(ω) and related microscopic parameters were obtained. As the T/sub c/ and gap increase, a movement of the lowest phonon branch to lower energies is observed with a resultant decrease in (ω 2 ). Thus lambda increases with T/sub c/ while (ω 2 ) decreases in agreement with the idea that mode softening is a major factor in the increase of T/sub c/ with approach to stoichiometry as previously found in Nb 3 Al by Kwo and Geballe

  3. Flat Ge-doped optical fibres for food irradiation dosimetry

    International Nuclear Information System (INIS)

    Noor, N. Mohd; Jusoh, M. A.; Razis, A. F. Abdull; Alawiah, A.; Bradley, D. A.

    2015-01-01

    Exposing food to radiation can improve hygiene quality, germination control, retard sprouting, and enhance physical attributes of the food product. To provide for food safety, radiation dosimetry in irradiated food is required. Herein, fabricated germanium doped (Ge-doped) optical fibres have been used. The fibres have been irradiated using a gamma source irradiator, doses in the range 1 kGy to 10 kGy being delivered. Using Ge-doped optical fibres of variable size, type and dopant concentration, study has been made of linearity, reproducibility, and fading. The thermoluminescence (TL) yield of the fibres were obtained and compared. The fibres exhibit a linear dose response over the investigated range of doses, with mean reproducibility to within 2.69 % to 8.77 %, exceeding the dose range of all commercial dosimeters used in evaluating high doses for the food irradiation industry. TL fading of the Ge-doped flat fibres has been found to be < 13%

  4. Flat Ge-doped optical fibres for food irradiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Noor, N. Mohd; Jusoh, M. A. [Department of Imaging, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Razis, A. F. Abdull [Food Safety Research Centre, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Laboratory of UPM-MAKNA Cancer Research, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Alawiah, A. [Faculty of Engineering and Technology, Multimedia University, 75450 Malacca (Malaysia); Bradley, D. A. [Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-04-24

    Exposing food to radiation can improve hygiene quality, germination control, retard sprouting, and enhance physical attributes of the food product. To provide for food safety, radiation dosimetry in irradiated food is required. Herein, fabricated germanium doped (Ge-doped) optical fibres have been used. The fibres have been irradiated using a gamma source irradiator, doses in the range 1 kGy to 10 kGy being delivered. Using Ge-doped optical fibres of variable size, type and dopant concentration, study has been made of linearity, reproducibility, and fading. The thermoluminescence (TL) yield of the fibres were obtained and compared. The fibres exhibit a linear dose response over the investigated range of doses, with mean reproducibility to within 2.69 % to 8.77 %, exceeding the dose range of all commercial dosimeters used in evaluating high doses for the food irradiation industry. TL fading of the Ge-doped flat fibres has been found to be < 13%.

  5. Isotope enrichment

    International Nuclear Information System (INIS)

    Garbuny, M.

    1979-01-01

    The invention discloses a method for deriving, from a starting material including an element having a plurality of isotopes, derived material enriched in one isotope of the element. The starting material is deposited on a substrate at less than a critical submonatomic surface density, typically less than 10 16 atoms per square centimeter. The deposit is then selectively irradiated by a laser (maser or electronic oscillator) beam with monochromatic coherent radiation resonant with the one isotope causing the material including the one istope to escape from the substrate. The escaping enriched material is then collected. Where the element has two isotopes, one of which is to be collected, the deposit may be irradiated with radiation resonant with the other isotope and the residual material enriched in the one isotope may be evaporated from the substrate and collected

  6. SiGe derivatization by spontaneous reduction of aryl diazonium salts

    Science.gov (United States)

    Girard, A.; Geneste, F.; Coulon, N.; Cardinaud, C.; Mohammed-Brahim, T.

    2013-10-01

    Germanium semiconductors have interesting properties for FET-based biosensor applications since they possess high surface roughness allowing the immobilization of a high amount of receptors on a small surface area. Since SiGe combined low cost of Si and intrinsic properties of Ge with high mobility carriers, we focused the study on this particularly interesting material. The comparison of the efficiency of a functionalization process involving the spontaneous reduction of diazonium salts is studied on Si(1 0 0), SiGe and Ge semiconductors. XPS analysis of the functionalized surfaces reveals the presence of a covalent grafted layer on all the substrates that was confirmed by AFM. Interestingly, the modified Ge derivatives have still higher surface roughness after derivatization. To support the estimated thickness by XPS, a step measurement of the organic layers is done by AFM or by profilometer technique after a O2 plasma etching of the functionalized layer. This original method is well-adapted to measure the thickness of thin organic films on rough substrates such as germanium. The analyses show a higher chemical grafting on SiGe substrates compared with Si and Ge semiconductors.

  7. Synthesis, structure and electronic structure of a new polymorph of CaGe2

    International Nuclear Information System (INIS)

    Tobash, Paul H.; Bobev, Svilen

    2007-01-01

    Reported are the flux synthesis, the crystal structure determination, the properties and the band structure calculations of a new polymorph of CaGe 2 , which crystallizes with the hexagonal space group P6 3 mc (no. 186) with cell parameters of a=3.9966(9) and c=10.211(4)A (Z=2; Pearson's code hP6). The structure can be viewed as puckered layers of three-bonded germanium atoms, ∼ 2 [Ge 2 ] 2- , which are stacked along the direction of the c-axis in an ABAB-fashion. The germanium polyanionic layers are separated by the Ca cations. As such, this structure is closely related to the structure of the other CaGe 2 polymorph, which crystallizes with the rhombohedral CaSi 2 type in the R3-bar m space group (No. 166), where the ∼ 2 [Ge 2 ] 2- layers are arranged in an AA'BB'CC'-fashion, and are also interspaced by Ca 2+ cations. LMTO calculations suggest that in spite of the formal closed-shell configuration for all atoms and the apparent adherence to the Zintl rules for electron counting, i.e., Ca 2+ [3b-Ge 1- ] 2 ), the phase will be a poor metal due to a small Ca-3d-Ge-4p band overlap. Magnetic susceptibility measurements as a function of the temperature indicate that the new CaGe 2 polymorph exhibits weak, temperature independent, Pauli-paramagnetism

  8. Optical spectroscopic characterization of amorphous germanium carbide materials obtained by X-Ray Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Paola Antoniotti

    2015-05-01

    Full Text Available Amorphous germanium carbides have been prepared by X-ray activated Chemical Vapor Deposition from germane/allene systems. The allene percentage and irradiation time (total dose were correlated to the composition, the structural features, and the optical coefficients of the films, as studied by IR and UV-VIS spectroscopic techniques. The materials composition is found to change depending on both the allene percentage in the mixture and the irradiation time. IR spectroscopy results indicate that the solids consist of randomly bound networks of carbon and germanium atoms with hydrogen atoms terminating all the dangling bonds. Moreover, the elemental analysis results, the absence of both unsaturated bonds and CH3 groups into the solids and the absence of allene autocondensation reactions products, indicate that polymerization reactions leading to mixed species, containing Ge-C bonds, are favored. Eopt values around 3.5 eV have been found in most of the cases, and are correlated with C sp3-bonding configuration. The B1/2 value, related to the order degree, has been found to be dependent on solid composition, atoms distribution in the material and hydrogenation degree of carbon atoms.

  9. Theoretical study of the localization-delocalization transition in amorphous molybdenum-germanium alloys

    International Nuclear Information System (INIS)

    Ding, K.; Andersen, H.C.

    1987-01-01

    Electronic structure calculations were performed for amorphous germanium and amorphous alloys of molybdenum and germanium. The calculations used Harrison's universal linear-combination-of-atomic-orbitals parameters to generate one-electron Hamiltonians for structural configurations obtained from molecular-dynamics simulations. The density of states calculated for a model of a-Ge showed a distinct pseudogap, although with an appreciable density of states at the minimum. The states in the pseudogap are localized. As the concentration of Mo atoms increases, the pseudogap of the density of states is gradually filled up. The density of states at the Fermi energy calculated for our model of the alloys agrees quite well with that experimentally determined by Yoshizumi, Geballe, and co-workers. The localization index for the states at the Fermi energy is a decreasing function of Mo concentration in the range of 2--14 at. % Mo and the localization length is an increasing function of molybdenum concentration. These results are consistent with the experimental observation of an insulator-metal transition at about 10 at. % Mo

  10. Annealing effect on spin density of broken bonds and on the structure of amorphous germanium

    International Nuclear Information System (INIS)

    Bukhan'ko, F.N.; Okunev, V.D.; Samojlenko, Z.A.

    1989-01-01

    Dependence of volumetric spin density of broken bonds in a-Ge films, produced by cathode sputtering in argon, on the annealing temperature is investigated by ESR method. The film structure is controlled by the X-ray method. Two ESR lines with g=2.019 and g=2.003, their intensities changing non-monotonously with annealing temperature are observed. The line with g=2.019 is typical of only amorphous germanium state, and the line with g=2.003 is preserved after film crystallization. Under comparison of results with structural data a conclusion is made that the observed lines in ESR spectra are linked with broken bonds in peripheral regions of two types of clusters. The line with g=2.003 is conditioned by broken bonds in the peripheral cluster regions with standard cubic atom packing and the line with g=2.019 is linked with clusters of hexagonal type which is not typical of crystalline germanium standard structure

  11. Oxygen defect processes in silicon and silicon germanium

    KAUST Repository

    Chroneos, A.; Sgourou, E. N.; Londos, C. A.; Schwingenschlö gl, Udo

    2015-01-01

    Silicon and silicon germanium are the archetypical elemental and alloy semiconductor materials for nanoelectronic, sensor, and photovoltaic applications. The investigation of radiation induced defects involving oxygen, carbon, and intrinsic defects is important for the improvement of devices as these defects can have a deleterious impact on the properties of silicon and silicon germanium. In the present review, we mainly focus on oxygen-related defects and the impact of isovalent doping on their properties in silicon and silicon germanium. The efficacy of the isovalent doping strategies to constrain the oxygen-related defects is discussed in view of recent infrared spectroscopy and density functional theory studies.

  12. Oxygen defect processes in silicon and silicon germanium

    KAUST Repository

    Chroneos, A.

    2015-06-18

    Silicon and silicon germanium are the archetypical elemental and alloy semiconductor materials for nanoelectronic, sensor, and photovoltaic applications. The investigation of radiation induced defects involving oxygen, carbon, and intrinsic defects is important for the improvement of devices as these defects can have a deleterious impact on the properties of silicon and silicon germanium. In the present review, we mainly focus on oxygen-related defects and the impact of isovalent doping on their properties in silicon and silicon germanium. The efficacy of the isovalent doping strategies to constrain the oxygen-related defects is discussed in view of recent infrared spectroscopy and density functional theory studies.

  13. Dosimetric properties of germanium doped calcium borate glass subjected to 6 MV and 10 MV X-ray irradiations

    Energy Technology Data Exchange (ETDEWEB)

    Tengku Kamarul Bahri, T.N.H., E-mail: tnhidayah2@gmail.com [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru (Malaysia); Wagiran, H.; Hussin, R.; Saeed, M.A. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru (Malaysia); Hossain, I. [Department of Physics, College of Science and Arts, King Abdul Aziz University, 21911 Rabigh (Saudi Arabia); Ali, H. [Department of Radiotherapy and Oncology, Hospital Sultan Ismail, 81100 Johor Bahru (Malaysia)

    2014-10-01

    Highlights: •The TL properties of 29.9CaO–70B{sub 2}O{sub 3}: 0.1GeO{sub 2} glass has been investigated. •We exposed glass samples to 6 MV and 10 MV in a dose range of 0.5–4.0 Gy. •This glass has a potential material to be used for application in radiotherapy. -- Abstract: Germanium doped calcium borate glasses are investigated in term of thermoluminescence properties to seek their possibility to use as glass radiation dosimeter. The samples were exposed to 6 MV, and 10 MV photon beams in a dose range of 0.5–4.0 Gy. There is a single and broad thermoluminescence glow curve that exhibits its maximum intensity at about 300 °C. Linear dose response behavior has been found in this dose range for the both photon energies. Effective atomic number, TL sensitivity, and reproducibility have also been studied. It is found that the sensitivity of germanium doped sample at 6 MV is only 1.28% and it is superior to the sensitivity at 10 MV. The reproducibility of germanium doped sample is good with a percentage of relative error less than 10%. The results indicate that this glass has a potential to be used as a radiation dosimetry, especially for application in radiotherapy.

  14. Dosimetric properties of germanium doped calcium borate glass subjected to 6 MV and 10 MV X-ray irradiations

    International Nuclear Information System (INIS)

    Tengku Kamarul Bahri, T.N.H.; Wagiran, H.; Hussin, R.; Saeed, M.A.; Hossain, I.; Ali, H.

    2014-01-01

    Highlights: •The TL properties of 29.9CaO–70B 2 O 3 : 0.1GeO 2 glass has been investigated. •We exposed glass samples to 6 MV and 10 MV in a dose range of 0.5–4.0 Gy. •This glass has a potential material to be used for application in radiotherapy. -- Abstract: Germanium doped calcium borate glasses are investigated in term of thermoluminescence properties to seek their possibility to use as glass radiation dosimeter. The samples were exposed to 6 MV, and 10 MV photon beams in a dose range of 0.5–4.0 Gy. There is a single and broad thermoluminescence glow curve that exhibits its maximum intensity at about 300 °C. Linear dose response behavior has been found in this dose range for the both photon energies. Effective atomic number, TL sensitivity, and reproducibility have also been studied. It is found that the sensitivity of germanium doped sample at 6 MV is only 1.28% and it is superior to the sensitivity at 10 MV. The reproducibility of germanium doped sample is good with a percentage of relative error less than 10%. The results indicate that this glass has a potential to be used as a radiation dosimetry, especially for application in radiotherapy

  15. Nanoscale measurements of phosphorous-induced lattice expansion in nanosecond laser annealed germanium

    Science.gov (United States)

    Boninelli, S.; Milazzo, R.; Carles, R.; Houdellier, F.; Duffy, R.; Huet, K.; La Magna, A.; Napolitani, E.; Cristiano, F.

    2018-05-01

    Laser Thermal Annealing (LTA) at various energy densities was used to recrystallize and activate amorphized germanium doped with phosphorous by ion implantation. The structural modifications induced during the recrystallization and the related dopant diffusion were first investigated. After LTA at low energy densities, the P electrical activation was poor while the dopant distribution was mainly localized in the polycrystalline Ge resulting from the anneal. Conversely, full dopant activation (up to 1 × 1020 cm-3) in a perfectly recrystallized material was observed after annealing at higher energy densities. Measurements of lattice parameters performed on the fully activated structures show that P doping results in a lattice expansion, with a perpendicular lattice strain per atom βPs = +0.7 ± 0.1 Å3. This clearly indicates that, despite the small atomic radius of P compared to Ge, the "electronic contribution" to the lattice parameter modification (due to the increased hydrostatic deformation potential in the conduction band of P doped Ge) is larger than the "size mismatch contribution" associated with the atomic radii. Such behavior, predicted by theory, is observed experimentally for the first time, thanks to the high sensitivity of the measurement techniques used in this work.

  16. Epitaxial Growth of Germanium on Silicon for Light Emitters

    Directory of Open Access Journals (Sweden)

    Chengzhao Chen

    2012-01-01

    Full Text Available This paper describes the role of Ge as an enabler for light emitters on a Si platform. In spite of the large lattice mismatch of ~4.2% between Ge and Si, high-quality Ge layers can be epitaxially grown on Si by ultrahigh-vacuum chemical vapor deposition. Applications of the Ge layers to near-infrared light emitters with various structures are reviewed, including the tensile-strained Ge epilayer, the Ge epilayer with a delta-doping SiGe layer, and the Ge/SiGe multiple quantum wells on Si. The fundamentals of photoluminescence physics in the different Ge structures are discussed briefly.

  17. Silicon-germanium and platinum silicide nanostructures for silicon based photonics

    Science.gov (United States)

    Storozhevykh, M. S.; Dubkov, V. P.; Arapkina, L. V.; Chizh, K. V.; Mironov, S. A.; Chapnin, V. A.; Yuryev, V. A.

    2017-05-01

    This paper reports a study of two types of silicon based nanostructures prospective for applications in photonics. The first ones are Ge/Si(001) structures forming at room temperature and reconstructing after annealing at 600°C. Germanium, being deposited from a molecular beam at room temperature on the Si(001) surface, forms a thin granular film composed of Ge particles with sizes of a few nanometers. A characteristic feature of these films is that they demonstrate signs of the 2 x 1 structure in their RHEED patterns. After short-term annealing at 600°C under the closed system conditions, the granular films reconstruct to heterostructures consisting of a Ge wetting layer and oval clusters of Ge. A mixed type c(4x2) + p(2x2) reconstruction typical to the low-temperature MBE (Tgr Ge. The other type of the studied nanostructures is based on Pt silicides. This class of materials is one of the friendliest to silicon technology. But as silicide film thickness reaches a few nanometers, low resistivity becomes of primary importance. Pt3Si has the lowest sheet resistance among the Pt silicides. However, the development of a process of thin Pt3Si films formation is a challenging task. This paper describes formation of a thin Pt3Si/Pt2Si structures at room temperature on poly-Si films. Special attention is paid upon formation of poly-Si and amorphous Si films on Si3N4 substrates at low temperatures.

  18. Effects of time-temperature profiles on glow curves of germanium-doped optical fibre

    Science.gov (United States)

    Lam, S. E.; Alawiah, A.; Bradley, D. A.; Mohd Noor, N.

    2017-08-01

    The Germanium (Ge) doped silica optical fibres have demonstrated the great potential to be developed as a thermoluminescent (TL) dosimeter that can be used in various applications in radiotherapy, diagnostic radiology, UV dosimetry system and food irradiation industry. Different time-temperature profile (TTP) parameters of the TL reader have been employed by many researchers in various of TL studies. Nevertheless, none of those studies adequately addressed the effects of the reader's preheat temperature and heating rate on the kinetic parameters of the TL glow curve specifically, the Ge-doped silica optical fibres. This research addresses the issue of TTP parameters with special attention to the determination of the kinetic parameters of the glow curve. The glow curve responses were explored and the kinetic parameters were analyzed by the WinGCF software, to show the effect of the preheat temperature and heating rate of the reader on Ge-doped fibre irradiated with 18 Gy of 6 MV photons radiation. The effect of TTP parameters was discussed and compared against the commercial fibre and tailored made fibre of 6 mol% Ge-doped of flat and cylindrical shape. The deconvolution of glow peaks and the kinetic parameters were obtained by the WinGCF software. This enables to fit accurately (1.5%Ge-doped silica optical fibres.

  19. Metal-oxide-semiconductor devices based on epitaxial germanium-carbon layers grown directly on silicon substrates by ultra-high-vacuum chemical vapor deposition

    Science.gov (United States)

    Kelly, David Quest

    After the integrated circuit was invented in 1959, complementary metal-oxide-semiconductor (CMOS) technology soon became the mainstay of the semiconductor industry. Silicon-based CMOS has dominated logic technologies for decades. During this time, chip performance has grown at an exponential rate at the cost of higher power consumption and increased process complexity. The performance gains have been made possible through scaling down circuit dimensions by improvements in lithography capabilities. Since scaling cannot continue forever, researchers have vigorously pursued new ways of improving the performance of metal-oxide-semiconductor field-effect transistors (MOSFETs) without having to shrink gate lengths and reduce the gate insulator thickness. Strained silicon, with its ability to boost transistor current by improving the channel mobility, is one of the methods that has already found its way into production. Although not yet in production, high-kappa dielectrics have also drawn wide interest in industry since they allow for the reduction of the electrical oxide thickness of the gate stack without having to reduce the physical thickness of the dielectric. Further out on the horizon is the incorporation of high-mobility materials such as germanium (Ge), silicon-germanium (Si1-xGe x), and the III-V semiconductors. Among the high-mobility materials, Ge has drawn the most attention because it has been shown to be compatible with high-kappa dielectrics and to produce high drive currents compared to Si. Among the most difficult challenges for integrating Ge on Si is finding a suitable method for reducing the number of crystal defects. The use of strain-relaxed Si1- xGex buffers has proven successful for reducing the threading dislocation density in Ge epitaxial layers, but questions remain as to the viability of this method in terms of cost and process complexity. This dissertation presents research on thin germanium-carbon (Ge 1-yCy layers on Si for the fabrication

  20. Germanium detectors and natural radioactivity in food

    Energy Technology Data Exchange (ETDEWEB)

    Garbini, Lucia [Max-Planck-Institut fuer Physik, Muenchen (Germany); Collaboration: GeDet-Collaboration

    2013-07-01

    Potassium is a very important mineral for many physiological processes, like fluid balance, protein synthesis and signal transmission in nerves. Many aliments like raisins, bananas or chocolate contain potassium. Natural potassium contains 0.012% of the radioactive isotope Potassium 40. This isotope decays via β{sup +} decay into a metastable state of Argon 40, which reaches its ground state emitting a gamma of 1460 keV. A commercially produced Germanium detector has been used to measure the energy spectra of different selected food samples. It was calibrated with KCl and potassium contents were extracted. Results verify the high potassium content of commonly recommended food samples. However, the measurement quantitatively differ from the expectations in several cases. One of the most interesting results concerns chocolate bars with different percentages of cacao.

  1. Carbon in high-purity germanium

    International Nuclear Information System (INIS)

    Haller, E.E.; Hansen, W.L.; Luke, P.; McMurray, R.; Jarrett, B.

    1981-10-01

    Using 14 C-spiked pyrolytic graphite-coated quartz crucibles for the growth of nine ultra-pure germanium single crystals, we have determined the carbon content and distribution in these crystals. Using autoradiography, we observe a rapidly decreasing carbon cluster concentration in successively grown crystals. Nuclear radiation detectors made from the crystals measure the betas from the internally decaying 14 C nuclei with close to 100% efficiency. An average value for the total carbon concentration [ 14 C + 12 C] is approx. 2 x 10 14 cm -3 , a value substantially larger than expected from earlier metallurgical studies. Contrary to the most recent measurement, we find the shape of the beta spectrum to agree very well with the statistical shape predicted for allowed transitions

  2. Radiation-electromagnetic effect in germanium monocrystals

    International Nuclear Information System (INIS)

    Kikoin, I.K.; Kikoin, L.I.; Lazarev, S.D.

    1980-01-01

    Experimentally investigated is the radiation-electromagnetic effect (REM) in germanium monocrystals on excitation of excess current carriers by α particles, protons and X-rays in magnetic fields up to 8 kOe. A cyclotron was used as an α particle source, and a standard X-ray tube with a copper anode - as an X-ray source. The e.m.f. of the REM effect linearly increases with the increase of the magnetic field and is proportional to the charged particle flux at small flux values, saturation occurs at great flux values (approximately 5x10 11 part./cm 2 xs). In the 4-40 MeV energy range the e.m.f. of the REM effect practically does not depend on the α particle energy. On irradiation of the samples with a grinding front surface the REM e.m.f. changes its sign. The REM and Hall effect measurement on α particle irradiated samples has shown that during irradiation a p-n transition is formed in the samples, which must be taken into account while studying the REM effect. The e.m.f. measured for the even REM effect quadratically increases with the magnetic field increase. The barrier radiation-voltaic effect (the effect e.m.f. is measured between the irradiated and nonirradiated sample faces) is studied. Using special masks the samples with a set of consecutive p-n transitions are produced by irradiation of germanium crystals by α particles. Investigation of the photovoltaic and photoelectromagnetic effects on such samples has shown that using this method the efficiency of the REM devices can be increased

  3. Silicon and Germanium (111) Surface Reconstruction

    Science.gov (United States)

    Hao, You Gong

    Silicon (111) surface (7 x 7) reconstruction has been a long standing puzzle. For the last twenty years, various models were put forward to explain this reconstruction, but so far the problem still remains unsolved. Recent ion scattering and channeling (ISC), scanning tunneling microscopy (STM) and transmission electron diffraction (TED) experiments reveal some new results about the surface which greatly help investigators to establish better models. This work proposes a silicon (111) surface reconstruction mechanism, the raising and lowering mechanism which leads to benzene -like ring and flower (raised atom) building units. Based on these building units a (7 x 7) model is proposed, which is capable of explaining the STM and ISC experiment and several others. Furthermore the building units of the model can be used naturally to account for the germanium (111) surface c(2 x 8) reconstruction and other observed structures including (2 x 2), (5 x 5) and (7 x 7) for germanium as well as the (/3 x /3)R30 and (/19 x /19)R23.5 impurity induced structures for silicon, and the higher temperature disordered (1 x 1) structure for silicon. The model is closely related to the silicon (111) surface (2 x 1) reconstruction pi-bonded chain model, which is the most successful model for the reconstruction now. This provides an explanation for the rather low conversion temperature (560K) of the (2 x 1) to the (7 x 7). The model seems to meet some problems in the explanation of the TED result, which is explained very well by the dimer, adatom and stacking fault (DAS) model proposed by Takayanagi. In order to explain the TED result, a variation of the atomic scattering factor is proposed. Comparing the benzene-like ring model with the DAS model, the former needs more work to explain the TED result and the later has to find a way to explain the silicon (111) surface (1 x 1) disorder experiment.

  4. Room-temperature ferromagnetic Cr-doped Ge/GeOx core–shell nanowires

    Science.gov (United States)

    Katkar, Amar S.; Gupta, Shobhnath P.; Motin Seikh, Md; Chen, Lih-Juann; Walke, Pravin S.

    2018-06-01

    The Cr-doped tunable thickness core–shell Ge/GeOx nanowires (NWs) were synthesized and characterized using x-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy and magnetization studies. The shell thickness increases with the increase in synthesis temperature. The presence of metallic Cr and Cr3+ in core–shell structure was confirmed from XPS study. The magnetic property is highly sensitive to the core–shell thickness and intriguing room temperature ferromagnetism is realized only in core–shell NWs. The magnetization decreases with an increase in shell thickness and practically ceases to exist when there is no core. These NWs show remarkably high Curie temperature (TC > 300 K) with the dominating values of its magnetic remanence (MR) and coercivity (HC) compared to germanium dilute magnetic semiconductor nanomaterials. We believe that our finding on these Cr-doped Ge/GeOX core–shell NWs has the potential to be used as a hard magnet for future spintronic devices, owing to their higher characteristic values of ferromagnetic ordering.

  5. Lattice site and thermal stability of transition metals in germanium

    CERN Document Server

    Augustyns, Valérie; Pereira, Lino

    Although the first transistor was based on germanium, current chip technology mainly uses silicon due to its larger abundance, a lower price and higher quality silicon-oxide. However, a very important goal in microelectronics is to obtain faster integrated circuits. The advantages of germanium compared to silicon (e.g. a higher mobility of the charge carriers) motivates further research on germanium based materials. Semiconductor doping (e.g. introducing impurities into silicon and germanium in order to alter - and control - their properties) can be done by ion implantation or by in situ doping, whereby the host material is doped during growth. This thesis focuses on introducing dopants by ion implantation. The implantation as well as the subsequent measurements were performed in ISOLDE (CERN) using the emission channeling technique. Although ion implantation generates undesired defects in the host material (e.g. vacancies), such damage can be reduced by performing the implantation at an elevated temperature....

  6. Vacancy-acceptor complexes in germanium produced by ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Feuser, U.; Vianden, R. (Inst. fuer Strahlen- und Kernphysik, Univ. Bonn (Germany)); Alves, E.; Silva, M.F. da (Dept. de Fisica, ICEN/LNETI, Sacavem (Portugal)); Szilagyi, E.; Paszti, F. (Central Research Inst. for Physics, Hungarian Academy of Sciences, Budapest (Hungary)); Soares, J.C. (Centro de Fisica Nuclear, Univ. Lisbon (Portugal))

    1991-07-01

    Combining results obtained by the {gamma}-{gamma} perturbed angular correlation method, Rutherford backscattering and elastic recoil detection of hydrogen, a defect complex formed in germanium by indium implantation is identified as a vacancy trapped by the indium probe. (orig.).

  7. Thermoelectric cross-plane properties on p- and n-Ge/Si{sub x}Ge{sub 1-x} superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Ferre Llin, L.; Samarelli, A. [University of Glasgow, School of Engineering, Oakfield Avenue, Glasgow G12 8LT (United Kingdom); Cecchi, S.; Chrastina, D.; Isella, G. [L-NESS, Politecnico di Milano, Via Anzani 42, 22100 Como (Italy); Müller Gubler, E. [ETH, Electron Microscopy ETH Zurich, Wolgang-Pauli-Str. Ch-8093 Zurich (Switzerland); Etzelstorfer, T.; Stangl, J. [Johannes Kepler Universität, Institute of Semiconductor and Solid State Physics, A-4040 Linz (Austria); Paul, D.J., E-mail: Douglas.Paul@glasgow.ac.uk [University of Glasgow, School of Engineering, Oakfield Avenue, Glasgow G12 8LT (United Kingdom)

    2016-03-01

    Silicon and germanium materials have demonstrated an increasing attraction for energy harvesting, due to their sustainability and integrability with complementary metal oxide semiconductor and micro-electro-mechanical-system technology. The thermoelectric efficiencies for these materials, however, are very poor at room temperature and so it is necessary to engineer them in order to compete with telluride based materials, which have demonstrated at room temperature the highest performances in literature [1]. Micro-fabricated devices consisting of mesa structures with integrated heaters, thermometers and Ohmic contacts were used to extract the cross-plane values of the Seebeck coefficient and the thermal conductivity from p- and n-Ge/Si{sub x}Ge{sub 1-x} superlattices. A second device consisting in a modified circular transfer line method structure was used to extract the electrical conductivity of the materials. A range of p-Ge/Si{sub 0.5}Ge{sub 0.5} superlattices with different doping levels was investigated in detail to determine the role of the doping density in dictating the thermoelectric properties. A second set of n-Ge/Si{sub 0.3}Ge{sub 0.7} superlattices was fabricated to study the impact that quantum well thickness might have on the two thermoelectric figures of merit, and also to demonstrate a further reduction of the thermal conductivity by scattering phonons at different wavelengths. This technique has demonstrated to lower the thermal conductivity by a 25% by adding different barrier thicknesses per period. - Highlights: • Growth of epitaxial Ge/SiGe superlattices on Si substrates as energy harvesters • Study of cross-plane thermoelectric properties of Ge/SiGe superlattices at 300 K • Thermoelectric figures of merit studied as a function of doping density • Phonon scattering at different wavelengths to reduce thermal transport.

  8. Transient optical gain in germanium quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Chatterjee, Sangam; Lange, Christoph; Koester, Niko S.; Schaefer, Martin; Kira, Mackillo; Koch, Stephan W. [Faculty of Physics and Materials Sciences Center, Philipps-Universitaet Marburg (Germany); Chrastina, Daniel; Isella, Giovanni; Kaenel, Hans von [CNISM, Como (Italy); L-NESS, Dipartimento di Fisica del Politecnico di Milano, Como (Italy); Sigg, Hans [Laboratory for Micro and Nanotecnology, Paul Scherrer Institut, Villigen PSI (Switzerland)

    2010-07-01

    One of today's most-sought goals in semiconductor technology is the monolithic integration of microelectronics and photonics on Si. Optical gain is, in general, not expected for Si and Ge or its alloys due to the indirect nature of the band gap in this material system. Here, we show that Ge/SiGe QWs show transient optical gain and may thus be used as an optically-pumped amplifier at room temperature. Further, the nonequilibrium effects which govern the relaxation dynamics of the optically injected carrier distributions in this material were observed and analyzed using a microscopic many-body theory. Strong non-equilibrium gain was obtained on a sub-100 fs time scale. Long-lived gain arising from {gamma}-point transitions is overcompensated by a process bearing the character of free carrier absorption.

  9. Transfer-less flexible and transparent high-κ/metal gate germanium devices on bulk silicon (100)

    KAUST Repository

    Nassar, Joanna M.; Hussain, Aftab M.; Rojas, Jhonathan Prieto; Hussain, Muhammad Mustafa

    2014-01-01

    Flexible wearable electronics have been of great interest lately for the development of innovative future technology for various interactive applications in the field of consumer electronics and advanced healthcare, offering the promise of low-cost, lightweight, and multifunctionality. In the pursuit of this trend, high mobility channel materials need to be investigated on a flexible platform, for the development of flexible high performance devices. Germanium (Ge) is one of the most attractive alternatives for silicon (Si) for high-speed computational applications, due its higher hole and electron mobility. Thus, in this work we show a cost effective CMOS compatible process for transforming conventional rigid Ge metal oxide semiconductor capacitors (MOSCAPS) into a mechanically flexible and semi-transparent platform. Devices exhibit outstanding bendability with a bending radius of 0.24 cm, and semi-transparency up to 30 %, varying with respect to the diameter size of the release holes array.

  10. Spontaneous breaking of time-reversal symmetry in strongly interacting two-dimensional electron layers in silicon and germanium.

    Science.gov (United States)

    Shamim, S; Mahapatra, S; Scappucci, G; Klesse, W M; Simmons, M Y; Ghosh, A

    2014-06-13

    We report experimental evidence of a remarkable spontaneous time-reversal symmetry breaking in two-dimensional electron systems formed by atomically confined doping of phosphorus (P) atoms inside bulk crystalline silicon (Si) and germanium (Ge). Weak localization corrections to the conductivity and the universal conductance fluctuations were both found to decrease rapidly with decreasing doping in the Si:P and Ge:P delta layers, suggesting an effect driven by Coulomb interactions. In-plane magnetotransport measurements indicate the presence of intrinsic local spin fluctuations at low doping, providing a microscopic mechanism for spontaneous lifting of the time-reversal symmetry. Our experiments suggest the emergence of a new many-body quantum state when two-dimensional electrons are confined to narrow half-filled impurity bands.

  11. Transfer-less flexible and transparent high-κ/metal gate germanium devices on bulk silicon (100)

    KAUST Repository

    Nassar, Joanna M.

    2014-08-01

    Flexible wearable electronics have been of great interest lately for the development of innovative future technology for various interactive applications in the field of consumer electronics and advanced healthcare, offering the promise of low-cost, lightweight, and multifunctionality. In the pursuit of this trend, high mobility channel materials need to be investigated on a flexible platform, for the development of flexible high performance devices. Germanium (Ge) is one of the most attractive alternatives for silicon (Si) for high-speed computational applications, due its higher hole and electron mobility. Thus, in this work we show a cost effective CMOS compatible process for transforming conventional rigid Ge metal oxide semiconductor capacitors (MOSCAPS) into a mechanically flexible and semi-transparent platform. Devices exhibit outstanding bendability with a bending radius of 0.24 cm, and semi-transparency up to 30 %, varying with respect to the diameter size of the release holes array.

  12. Recycling of waste printed circuit boards with simultaneous enrichment of special metals by using alkaline melts: A green and strategically advantageous solution

    Energy Technology Data Exchange (ETDEWEB)

    Stuhlpfarrer, Philipp, E-mail: philipp-johannes.stuhlpfarrer@stud.unileoben.ac.at; Luidold, Stefan; Antrekowitsch, Helmut

    2016-04-15

    Highlights: • Removal of plastics. • Enrichment of In, Ga and Ge. • Low temperature. • No dioxines. - Abstract: The increasing consumption of electric and electronic equipment has led to a rise in toxic waste. To recover the metal fraction, a separation of the organic components is necessary because harmful substances such as chlorine, fluorine and bromine cause ecological damage, for example in the form of dioxins and furans at temperature above 400 °C. Hence, an alternative, environmentally friendly approach was investigated exploiting that a mixture of caustic soda and potassium hydroxide in eutectic composition melts below 200 °C, enabling a fast cracking of the long hydrocarbon chains. The trials demonstrate the removal of organic compounds without a loss of copper and precious metals, as well as a suppressed formation of hazardous off-gases. In order to avoid an input of alkaline elements into the furnace and ensuing problems with refractory materials, a washing step generates a sodium and potassium hydroxide solution, in which special metals like indium, gallium and germanium are enriched. Their concentrations facilitate the recovery of these elements, because otherwise they become lost in the typical recycling processes. The aim of this work was to find an environmental solution for the separation of plastics and metals as well as a strategically important answer for the recycling of printed circuit boards and mobile phones.

  13. Recycling of waste printed circuit boards with simultaneous enrichment of special metals by using alkaline melts: A green and strategically advantageous solution

    International Nuclear Information System (INIS)

    Stuhlpfarrer, Philipp; Luidold, Stefan; Antrekowitsch, Helmut

    2016-01-01

    Highlights: • Removal of plastics. • Enrichment of In, Ga and Ge. • Low temperature. • No dioxines. - Abstract: The increasing consumption of electric and electronic equipment has led to a rise in toxic waste. To recover the metal fraction, a separation of the organic components is necessary because harmful substances such as chlorine, fluorine and bromine cause ecological damage, for example in the form of dioxins and furans at temperature above 400 °C. Hence, an alternative, environmentally friendly approach was investigated exploiting that a mixture of caustic soda and potassium hydroxide in eutectic composition melts below 200 °C, enabling a fast cracking of the long hydrocarbon chains. The trials demonstrate the removal of organic compounds without a loss of copper and precious metals, as well as a suppressed formation of hazardous off-gases. In order to avoid an input of alkaline elements into the furnace and ensuing problems with refractory materials, a washing step generates a sodium and potassium hydroxide solution, in which special metals like indium, gallium and germanium are enriched. Their concentrations facilitate the recovery of these elements, because otherwise they become lost in the typical recycling processes. The aim of this work was to find an environmental solution for the separation of plastics and metals as well as a strategically important answer for the recycling of printed circuit boards and mobile phones.

  14. The reliability studies of nano-engineered SiGe HBTs using Pelletron accelerator

    Science.gov (United States)

    Prakash, A. P. Gnana; Praveen, K. C.; Pushpa, N.; Cressler, John D.

    2015-05-01

    The effects of high energy ions on the electrical characteristics of silicon-germanium heterojunction bipolar transistors (SiGe HBTs) were studied in the total dose of ranging from 600 krad to 100 Mrad (Si). The two generations (50 GHz and 200 GHz) of SiGe HBTs were exposed to 50 MeV lithium, 75 MeV boron and 100 MeV oxygen ions. The electrical characteristics of SiGe HBTs were studied before and after irradiation. The SiGe HBTs were exposed to 60Co gamma radiation in the same total dose. The results are systematically compared in order to understand the interaction of ions and ionizing radiation with SiGe HBTs.

  15. Noise Parameter Analysis of SiGe HBTs for Different Sizes in the Breakdown Region

    Directory of Open Access Journals (Sweden)

    Chie-In Lee

    2016-01-01

    Full Text Available Noise parameters of silicon germanium (SiGe heterojunction bipolar transistors (HBTs for different sizes are investigated in the breakdown region for the first time. When the emitter length of SiGe HBTs shortens, minimum noise figure at breakdown decreases. In addition, narrower emitter width also decreases noise figure of SiGe HBTs in the avalanche region. Reduction of noise performance for smaller emitter length and width of SiGe HBTs at breakdown resulted from the lower noise spectral density resulting from the breakdown mechanism. Good agreement between experimental and simulated noise performance at breakdown is achieved for different sized SiGe HBTs. The presented analysis can benefit the RF circuits operating in the breakdown region.

  16. The reliability studies of nano-engineered SiGe HBTs using Pelletron accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, A. P. Gnana, E-mail: gnanaprakash@physics.uni-mysore.ac.in; Praveen, K. C. [Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore, Karnataka-570006 (India); Pushpa, N. [Department of PG Studies in Physics, JSS College, Ooty Road, Mysore-570025 (India); Cressler, John D. [School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, 30332 (United States)

    2015-05-15

    The effects of high energy ions on the electrical characteristics of silicon-germanium heterojunction bipolar transistors (SiGe HBTs) were studied in the total dose of ranging from 600 krad to 100 Mrad (Si). The two generations (50 GHz and 200 GHz) of SiGe HBTs were exposed to 50 MeV lithium, 75 MeV boron and 100 MeV oxygen ions. The electrical characteristics of SiGe HBTs were studied before and after irradiation. The SiGe HBTs were exposed to {sup 60}Co gamma radiation in the same total dose. The results are systematically compared in order to understand the interaction of ions and ionizing radiation with SiGe HBTs.

  17. Gas Source Techniques for Molecular Beam Epitaxy of Highly Mismatched Ge Alloys

    Directory of Open Access Journals (Sweden)

    Chad A. Stephenson

    2016-12-01

    Full Text Available Ge and its alloys are attractive candidates for a laser compatible with silicon integrated circuits. Dilute germanium carbide (Ge1−xCx offers a particularly interesting prospect. By using a precursor gas with a Ge4C core, C can be preferentially incorporated in substitutional sites, suppressing interstitial and C cluster defects. We present a method of reproducible and upscalable gas synthesis of tetrakis(germylmethane, or (H3Ge4C, followed by the design of a hybrid gas/solid-source molecular beam epitaxy system and subsequent growth of defect-free Ge1−xCx by molecular beam epitaxy (MBE. Secondary ion mass spectroscopy, transmission electron microscopy and contactless electroreflectance confirm the presence of carbon with very high crystal quality resulting in a decrease in the direct bandgap energy. This technique has broad applicability to growth of highly mismatched alloys by MBE.

  18. Pulsed laser ablation of Germanium under vacuum and hydrogen environments at various fluences

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Muhammad Hassan [Centre for Advanced Studies in Physics, Government College University, Lahore (Pakistan); Bashir, Shazia, E-mail: shaziabashir@gcu.edu.pk [Centre for Advanced Studies in Physics, Government College University, Lahore (Pakistan); Rafique, Muhammad Shahid [Department of Physics, University of Engineering and Technology, Lahore (Pakistan); Dawood, Asadullah; Akram, Mahreen; Mahmood, Khaliq; Hayat, Asma; Ahmad, Riaz; Hussain, Tousif [Centre for Advanced Studies in Physics, Government College University, Lahore (Pakistan); Mahmood, Arshad [National Institute of Laser and Optronics (NILOP), Islamabad (Pakistan)

    2015-07-30

    Highlights: • Germanium targets were exposed under vacuum and H{sub 2} environment by nanosecond laser pulses. • The effect of laser fluence and ambient environment has been investigated. • The surface morphology is investigated by SEM analysis. • Raman and FTIR Spectroscopy are performed to reveal structural modification. • Electrical conductivity is probed by four probe method. - Abstract: Laser fluence and ambient environment play a significant role for the formation and development of the micro/nano-structures on the laser irradiated targets. Single crystal (1 0 0) Germanium (Ge) has been ablated under two environments of vacuum (10{sup −3} Torr) and hydrogen (100 Torr) at various fluences ranging from 4.5 J cm{sup −2} to 6 J cm{sup −2}. For this purpose KrF Excimer laser with wavelength of 248 nm, pulse duration of 18 ns and repetition rate of 20 Hz has been employed. Surface morphology has been observed by Scanning Electron Microscope (SEM). Whereas, structural modification of irradiated targets was explored by Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy. Electrical conductivity of the irradiated Ge is measured by four probe method. SEM analysis exhibits the formation of laser-induced periodic surface structures (LIPSS), cones and micro-bumps in both ambient environments (vacuum and hydrogen). The formation as well as development of these structures is strongly dependent upon the laser fluence and environmental conditions. The periodicity of LIPSS or ripples varies from 38 μm to 60 μm in case of vacuum whereas in case of hydrogen environment, the periodicity varies from 20 μm to 45 μm. The difference in number of ripples and periodicity as well as in shape and size of cones and bumps in vacuum and hydrogen is explained on the basis of confinement and shielding effect of plasma. FTIR spectroscopy reveals that no new bands are formed for laser ablated Ge under vacuum, whereas C−H stretching vibration band is

  19. High-Resolution Electron Energy Loss Studies of Oxygen, Hydrogen, Nitrogen, Nitric Oxide, and Nitrous Oxide Adsorption on Germanium Surfaces.

    Science.gov (United States)

    Entringer, Anthony G.

    The first high resolution electron energy loss spectroscopy (HREELS) studies of the oxidation and nitridation of germanium surfaces are reported. Both single crystal Ge(111) and disordered surfaces were studied. Surfaces were exposed to H, O_2, NO, N _2O, and N, after cleaning in ultra-high vacuum. The Ge surfaces were found to be non-reactive to molecular hydrogen (H_2) at room temperature. Exposure to atomic hydrogen (H) resulted hydrogen adsorption as demonstrated by the presence of Ge-H vibrational modes. The HREEL spectrum of the native oxide of Ge characteristic of nu -GeO_2 was obtained by heating the oxide to 200^circC. Three peaks were observed at 33, 62, and 106 meV for molecular oxygen (O_2) adsorbed on clean Ge(111) at room temperature. These peaks are indicative of dissociative bonding and a dominant Ge-O-Ge bridge structure. Subsequent hydrogen exposure resulted in a shift of the Ge-H stretch from its isolated value of 247 meV to 267 meV, indicative of a dominant +3 oxidation state. A high density of dangling bonds and defects and deeper oxygen penetration at the amorphous Ge surface result in a dilute bridge structure with a predominant +1 oxidation state for similar exposures. Molecules of N_2O decompose at the surfaces to desorbed N_2 molecules and chemisorbed oxygen atoms. In contrast, both oxygen and nitrogen are detected at the surfaces following exposure to NO molecules. Both NO and N_2O appear to dissociate and bond at the top surface layer. Molecular nitrogen (N_2) does not react with the Ge surfaces, however, a precursor Ge nitride is observed at room temperature following exposure to nitrogen atoms and ions. Removal of oxygen by heating of the NO-exposed surface to 550^circC enabled the identification of the Ge-N vibrational modes. These modes show a structure similar to that of germanium nitride. This spectrum is also identical to that of the N-exposed surface heated to 550^circC. Surface phonon modes of the narrow-gap semiconducting

  20. Use of Germanium as comparator and integral monitor of neutron flux in activation analysis; Utilizacion del germanio como comparador y monitor integral de flujo neutronico en analisis por activacion

    Energy Technology Data Exchange (ETDEWEB)

    Furnari, Juan C.; Cohen, Isaac M. [Comision Nacional de Energia Atomica, Buenos Aires (Argentina). Centro Atomico Ezeiza; Arribere, Maria A.; Kestelman, Abraham J. [Comision Nacional de Energia Atomica, San Carlos de Bariloche (Argentina). Centro Atomico Bariloche

    1997-10-01

    The possibility of using germanium as monitor of the thermal and epithermal components of the neutron flux, and comparator in parametric activation analysis, is discussed. The advantages and drawbacks associated to the use of this element are commented on, and the comparison with zirconium, in terms of the determination relative error, is performed. The utilisation of germanium as integral flux monitor, including the fast component of the neutron spectrum, is also discussed. Data corresponding to measurements of k{sub 0} factor for the most relevant gamma transitions from Ge-75 and Be-77 are presented, as well as the results of the reference material analysis, employing germanium as flux monitor and comparator in a simultaneous way. (author). 8 refs., 3 figs., 2 tabs.

  1. Uranium enrichment

    International Nuclear Information System (INIS)

    1991-08-01

    This paper reports that in 1990 the Department of Energy began a two-year project to illustrate the technical and economic feasibility of a new uranium enrichment technology-the atomic vapor laser isotope separation (AVLIS) process. GAO believes that completing the AVLIS demonstration project will provide valuable information about the technical viability and cost of building an AVLIS plant and will keep future plant construction options open. However, Congress should be aware that DOE still needs to adequately demonstrate AVLIS with full-scale equipment and develop convincing cost projects. Program activities, such as the plant-licensing process, that must be completed before a plant is built, could take many years. Further, an updated and expanded uranium enrichment analysis will be needed before any decision is made about building an AVLIS plant. GAO, which has long supported legislation that would restructure DOE's uranium enrichment program as a government corporation, encourages DOE's goal of transferring AVLIS to the corporation. This could reduce the government's financial risk and help ensure that the decision to build an AVLIS plant is based on commercial concerns. DOE, however, has no alternative plans should the government corporation not be formed. Further, by curtailing a planned public access program, which would have given private firms an opportunity to learn about the technology during the demonstration project, DOE may limit its ability to transfer AVLIS to the private sector

  2. Solution synthesis of lead seeded germanium nanowires and branched nanowire networks and their application as Li-ion battery anodes

    Science.gov (United States)

    Flynn, Grace; Palaniappan, Kumaranand; Sheehan, Martin; Kennedy, Tadhg; Ryan, Kevin M.

    2017-06-01

    Herein, we report the high density growth of lead seeded germanium nanowires (NWs) and their development into branched nanowire networks suitable for application as lithium ion battery anodes. The synthesis of the NWs from lead seeds occurs simultaneously in both the liquid zone (solution-liquid-solid (SLS) growth) and solvent rich vapor zone (vapor-liquid-solid (VLS) growth) of a high boiling point solvent growth system. The reaction is sufficiently versatile to allow for the growth of NWs directly from either an evaporated catalyst layer or from pre-defined nanoparticle seeds and can be extended to allowing extensive branched nanowire formation in a secondary reaction where these seeds are coated onto existing wires. The NWs are characterized using TEM, SEM, XRD and DF-STEM. Electrochemical analysis was carried out on both the single crystal Pb-Ge NWs and the branched Pb-Ge NWs to assess their suitability for use as anodes in a Li-ion battery. Differential capacity plots show both the germanium wires and the lead seeds cycle lithium and contribute to the specific capacity that is approximately 900 mAh g-1 for the single crystal wires, rising to approximately 1100 mAh g-1 for the branched nanowire networks.

  3. Degradation of SiGe devices by proton irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ohyama, Hidenori; Hayama, Kiyoteru [Kumamoto National Coll. of Technology, Nishigoshi (Japan); Vanhellemont, J; Takami, Yasukiyo; Sunaga, Hiromi; Nashiyama, Isamu; Uwatoko, Yoshiya; Poortmans, J; Caymax, M

    1997-03-01

    The degradation and recovery behavior of strained Si{sub 1-x}Ge{sub x} diodes and heterojunction bipolar transistors (HBTs) by irradiated by protons are studied. The degradation of device performance and the generation of lattice defects are reported as a function of fluence and germanium content and also compared extensively with previous results obtained on electron and neutron irradiated devices. In order to study the recovery behavior of the irradiated devices, isochronal annealing is performed. The radiation source dependence of the degradation is discussed taking into account the number of knock-on atoms and the nonionizing energy loss (NIEL). (author)

  4. Ion implantation of boron in germanium

    International Nuclear Information System (INIS)

    Jones, K.S.

    1985-05-01

    Ion implantation of 11 B + into room temperature Ge samples leads to a p-type layer prior to any post implant annealing steps. Variable temperature Hall measurements and deep level transient spectroscopy experiments indicate that room temperature implantation of 11 B + into Ge results in 100% of the boron ions being electrically active as shallow acceptor, over the entire dose range (5 x 10 11 /cm 2 to 1 x 10 14 /cm 2 ) and energy range (25 keV to 100 keV) investigated, without any post implant annealing. The concentration of damage related acceptor centers is only 10% of the boron related, shallow acceptor center concentration for low energy implants (25 keV), but becomes dominant at high energies (100 keV) and low doses ( 12 /cm 2 ). Three damage related hole traps are produced by ion implantation of 11 B + . Two of these hole traps have also been observed in γ-irradiated Ge and may be oxygen-vacancy related defects, while the third trap may be divacancy related. All three traps anneal out at low temperatures ( 0 C). Boron, from room temperature implantation of BF 2 + into Ge, is not substitutionally active prior to a post implant annealing step of 250 0 C for 30 minutes. After annealing additional shallow acceptors are observed in BF 2 + implanted samples which may be due to fluorine or flourine related complexes which are electrically active

  5. Results on neutrinoless double beta decay of 76Ge from the GERDA experiment

    Science.gov (United States)

    Palioselitis, Dimitrios

    2015-05-01

    The Germanium Detector Array (GERDA) experiment is searching for neutrinoless double beta (0νββ) decay of 76Ge, a lepton number violating nuclear process predicted by extensions of the Standard Model. GERDA is an array of bare germanium diodes immersed in liquid argon located at the Gran Sasso National Laboratory (LNGS) in Italy. The results of the GERDA Phase I data taking with a total exposure of 21.6 kg yr and a background index of 0.01 cts/(keV kg yr) are presented in this paper. No signal was observed and a lower limit of T1/20ν > 2.1×1025 yr (90% C.L.) was derived for the half-life of the 0νββ decay of 76Ge. Phase II of the experiment aims to reduce the background around the region of interest by a factor of ten.

  6. High Growth Rate Deposition of Hydrogenated Amorphous Silicon-Germanium Films and Devices Using ECR-PECVD

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yong [Iowa State Univ., Ames, IA (United States)

    2002-01-01

    Hydrogenated amorphous silicon germanium films (a-SiGe:H) and devices have been extensively studied because of the tunable band gap for matching the solar spectrum and mature the fabrication techniques. a-SiGe:H thin film solar cells have great potential for commercial manufacture because of very low cost and adaptability to large-scale manufacturing. Although it has been demonstrated that a-SiGe:H thin films and devices with good quality can be produced successfully, some issues regarding growth chemistry have remained yet unexplored, such as the hydrogen and inert-gas dilution, bombardment effect, and chemical annealing, to name a few. The alloying of the SiGe introduces above an order-of-magnitude higher defect density, which degrades the performance of the a-SiGe:H thin film solar cells. This degradation becomes worse when high growth-rate deposition is required. Preferential attachment of hydrogen to silicon, clustering of Ge and Si, and columnar structure and buried dihydride radicals make the film intolerably bad. The work presented here uses the Electron-Cyclotron-Resonance Plasma-Enhanced Chemical Vapor Deposition (ECR-PECVD) technique to fabricate a-SiGe:H films and devices with high growth rates. Helium gas, together with a small amount of H2, was used as the plasma species. Thickness, optical band gap, conductivity, Urbach energy, mobility-lifetime product, I-V curve, and quantum efficiency were characterized during the process of pursuing good materials. The microstructure of the a-(Si,Ge):H material was probed by Fourier-Transform Infrared spectroscopy. They found that the advantages of using helium as the main plasma species are: (1) high growth rate--the energetic helium ions break the reactive gas more efficiently than hydrogen ions; (2) homogeneous growth--heavy helium ions impinging on the surface promote the surface mobility of the reactive radicals, so that heteroepitaxy growth as clustering of Ge and Si, columnar structure are

  7. Impact of nitrogen plasma passivation on the Al/n-Ge contact

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Shumei; Mao, Danfeng [Department of Physics, Xiamen University, Xiamen, Fujian 361005 (China); Ruan, Yujiao [Xiamen Institute of Measurement and Testing, Xiamen, Fujian 361004 (China); Xu, Yihong; Huang, Zhiwei; Huang, Wei [Department of Physics, Xiamen University, Xiamen, Fujian 361005 (China); Chen, Songyan, E-mail: sychen@xmu.edu.cn [Department of Physics, Xiamen University, Xiamen, Fujian 361005 (China); Li, Cheng; Wang, Jianyuan [Department of Physics, Xiamen University, Xiamen, Fujian 361005 (China); Tang, Dingliang [College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005 (China)

    2016-09-15

    Highlights: • A thin GeO{sub x}N{sub y} layer was formed by N{sub 2} plasma. • The principal parameters of N{sub 2} plasma treatment and additional post anneal have a great impact on the Al/n-Ge contact. • A model was proposed to explain the variation of Schottky barrier height. • The GeO{sub x}N{sub y} layer was also benefit to achieve a low leakage current density for HfO{sub 2}/Ge MOS capacitors. - Abstract: Severe Fermi level pinning at the interface of metal/n-Ge leads to the formation of a Schottky barrier. Therefore, a high contact resistance is introduced, debasing the performance of Ge devices. In this study, a Ge surface was treated by nitrogen plasma to form an ultra-thin Germanium oxynitride (GeO{sub x}N{sub y}) passivation layer. It was found that the Schottky barrier height (SBH) of metal/n-Ge contact was strongly modulated by the GeO{sub x}N{sub y} interlayer, indicating alleviation of Fermi-level pinning effect. By adjusting the principal parameters of N{sub 2} plasma treatment and additional post anneal, a Quasi-ohmic Al/n-Ge contact was achieved. Furthermore, the introduced GeO{sub x}N{sub y} layer gave extremely lower leakage current density of the gate stack for HfO{sub 2}/Ge devices. These results demonstrate that GeO{sub x}N{sub y} formed by N{sub 2} plasma would be greatly beneficial to the fabrication of the Ge-based devices.

  8. Improved verification methods for safeguards verifications at enrichment plants

    International Nuclear Information System (INIS)

    Lebrun, A.; Kane, S. C.; Bourva, L.; Poirier, S.; Loghin, N. E.; Langlands, D.

    2009-01-01

    The International Atomic Energy Agency (IAEA) has initiated a coordinated research and development programme to improve its verification methods and equipment applicable to enrichment plants. The programme entails several individual projects to meet the objectives of the IAEA Safeguards Model Approach for Gas Centrifuge Enrichment Plants updated in 2006. Upgrades of verification methods to confirm the absence of HEU (highly enriched uranium) production have been initiated and, in particular, the Cascade Header Enrichment Monitor (CHEM) has been redesigned to reduce its weight and incorporate an electrically cooled germanium detector. Such detectors are also introduced to improve the attended verification of UF 6 cylinders for the verification of the material balance. Data sharing of authenticated operator weighing systems such as accountancy scales and process load cells is also investigated as a cost efficient and an effective safeguards measure combined with unannounced inspections, surveillance and non-destructive assay (NDA) measurement. (authors)

  9. Improved verification methods for safeguards verifications at enrichment plants

    Energy Technology Data Exchange (ETDEWEB)

    Lebrun, A.; Kane, S. C.; Bourva, L.; Poirier, S.; Loghin, N. E.; Langlands, D. [Department of Safeguards, International Atomic Energy Agency, Wagramer Strasse 5, A1400 Vienna (Austria)

    2009-07-01

    The International Atomic Energy Agency (IAEA) has initiated a coordinated research and development programme to improve its verification methods and equipment applicable to enrichment plants. The programme entails several individual projects to meet the objectives of the IAEA Safeguards Model Approach for Gas Centrifuge Enrichment Plants updated in 2006. Upgrades of verification methods to confirm the absence of HEU (highly enriched uranium) production have been initiated and, in particular, the Cascade Header Enrichment Monitor (CHEM) has been redesigned to reduce its weight and incorporate an electrically cooled germanium detector. Such detectors are also introduced to improve the attended verification of UF{sub 6} cylinders for the verification of the material balance. Data sharing of authenticated operator weighing systems such as accountancy scales and process load cells is also investigated as a cost efficient and an effective safeguards measure combined with unannounced inspections, surveillance and non-destructive assay (NDA) measurement. (authors)

  10. Modeling an array of encapsulated germanium detectors

    International Nuclear Information System (INIS)

    Kshetri, R

    2012-01-01

    A probability model has been presented for understanding the operation of an array of encapsulated germanium detectors generally known as composite detector. The addback mode of operation of a composite detector has been described considering the absorption and scattering of γ-rays. Considering up to triple detector hit events, we have obtained expressions for peak-to-total and peak-to-background ratios of the cluster detector, which consists of seven hexagonal closely packed encapsulated HPGe detectors. Results have been obtained for the miniball detectors comprising of three and four seven hexagonal closely packed encapsulated HPGe detectors. The formalism has been extended to the SPI spectrometer which is a telescope of the INTEGRAL satellite and consists of nineteen hexagonal closely packed encapsulated HPGe detectors. This spectrometer comprises of twelve detector modules surrounding the cluster detector. For comparison, we have considered a spectrometer comprising of nine detector modules surrounding the three detector configuration of miniball detector. In the present formalism, the operation of these sophisticated detectors could be described in terms of six probability amplitudes only. Using experimental data on relative efficiency and fold distribution of cluster detector as input, the fold distribution and the peak-to-total, peak-to-background ratios have been calculated for the SPI spectrometer and other composite detectors at 1332 keV. Remarkable agreement between experimental data and results from the present formalism has been observed for the SPI spectrometer.

  11. Growth of optical grade germanium crystals

    International Nuclear Information System (INIS)

    Waris, M.; Akhtar, M.J.; Mehmood, N.; Ashraf, M.; Siddique, M.

    2011-01-01

    A novel design of Czochralski( CZ ) growth station in a low frequency induction furnace is described and growth of optical grade Ge crystal as a test material is performed achieving a flat solid-liquid interface shape. Grown Ge crystals are annealed in air at 450 -500 deg. C for 4 hrs and then characterized by determination of crystallographic orientation by Laue (back-reflection of X-rays) method, dislocation density studies by etch-pits formation, measuring electrical resistivity by 4-probe technique, conductivity type determination by hot probe method, measurement of hardness on Moh's scale and optical transmission measurement in IR region. The results obtained are compared to those reported in the literature. The use of this growth station for other materials is suggested. (author)

  12. A Germanium Back Contact Type Thermophotovoltaic Cell

    International Nuclear Information System (INIS)

    Nagashima, Tomonori; Okumura, Kenichi; Yamaguchi, Masafumi

    2007-01-01

    A Ge back contact type photovoltaic cell has been proposed to reduce resistance loss for high current densities in thermophotovoltaic systems. The back contact structure requires less surface recombination velocities than conventional structures with front grid contacts. A SiO2/SiNx double anti-reflection coating including a high refractive index SiNx layer was studied. The SiNx layer has an enough passivation effect to obtain high efficiency. The quantum efficiency of the Ge cell was around 0.8 in the 800-1600 nm wavelength range. The conversion efficiency for infrared lights was estimated at 18% for a blackbody surface and 25% for a selective emitter by using the quantum efficiency and a simulation analysis

  13. Measurements of the total neutron cross-sections of poly- and mono-germanium crystals at neutron energies below 1 eV

    International Nuclear Information System (INIS)

    Maayouf, R.M.A.; Abdel-Kawy, A.; Abbas, Y.; Habib, N.; Adib, M.; Hamouda, I.

    1983-12-01

    Total neutron cross-section measurements have been performed for poly and mono-germanium crystals in the energy range from 2 meV-1eV. The measurements were performed using two TOF and a double axis crystal spectrometer installed at the ET-RR-1 reactor. The obtained neutron cross-sections were analyzed using the single level Breit-Wigner formula. The coherent scattering amplitude was determined from the Bragg reflections observed in the total neutron cross-section of Ge and the analysis of its neutron diffraction pattern. The incoherent and thermal diffuse scattering cross-sections of Ge were estimated from the analysis of the total cross-section data obtained for Ge mono-crystal

  14. Modeling the Efficiency of a Germanium Detector

    Science.gov (United States)

    Hayton, Keith; Prewitt, Michelle; Quarles, C. A.

    2006-10-01

    We are using the Monte Carlo Program PENELOPE and the cylindrical geometry program PENCYL to develop a model of the detector efficiency of a planar Ge detector. The detector is used for x-ray measurements in an ongoing experiment to measure electron bremsstrahlung. While we are mainly interested in the efficiency up to 60 keV, the model ranges from 10.1 keV (below the Ge absorption edge at 11.1 keV) to 800 keV. Measurements of the detector efficiency have been made in a well-defined geometry with calibrated radioactive sources: Co-57, Se-75, Ba-133, Am-241 and Bi-207. The model is compared with the experimental measurements and is expected to provide a better interpolation formula for the detector efficiency than simply using x-ray absorption coefficients for the major constituents of the detector. Using PENELOPE, we will discuss several factors, such as Ge dead layer, surface ice layer and angular divergence of the source, that influence the efficiency of the detector.

  15. Special Cryostats for Lithium Compensated Germanium Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lauber, A; Malmsten, B; Rosencrantz, B

    1968-05-15

    In many applications of Ge(Li) detectors an extreme design of the cryostat is desirable. One example is a coincidence or anticoincidence setup where the Ge(Li) detector is surrounded by one or several other detectors, usually Nal(Tl) crystals or plastic scintillators. To be usable in this arrangement the part of the cryostat containing the Ge(Li) detector should have the form of a long hood, with the detector placed at its very end. The diameter of the hood should be as small as detector dimensions permit. Excellent energy resolution and reasonably low liquid nitrogen consumption must be retained. Two cryostats fulfilling these conditions will be described. For the first cryostat emphasis lay on the reduction of the hood diameter to an absolute minimum; for the other incorporation of a device regulating the temperature of the cryostat surface was required. The difficulties encountered will be discussed; they were primarily connected with the necessity of combining minimum temperature loss at the detector position with extreme cryostat compactness and cold finger length. The incorporation of a cooled FET transistor in the cryostat will also be described. The gamma spectrometers using the cryostats gave resolutions down to 2.8 keV FWHM for the 1173 keV gamma line from Co 60 and 1.2 keV FWHM for the 122 keV line from Co 57.

  16. Reaction studies of hot silicon, germanium and carbon atoms

    International Nuclear Information System (INIS)

    Gaspar, P.P.

    1990-01-01

    The goal of this project was to increase the authors understanding of the interplay between the kinetic and electronic energy of free atoms and their chemical reactivity by answering the following questions: (1) what is the chemistry of high-energy carbon silicon and germanium atoms recoiling from nuclear transformations; (2) how do the reactions of recoiling carbon, silicon and germanium atoms take place - what are the operative reaction mechanisms; (3) how does the reactivity of free carbon, silicon and germanium atoms vary with energy and electronic state, and what are the differences in the chemistry of these three isoelectronic atoms? This research program consisted of a coordinated set of experiments capable of achieving these goals by defining the structures, the kinetic and internal energy, and the charge states of the intermediates formed in the gas-phase reactions of recoiling silicon and germanium atoms with silane, germane, and unsaturated organic molecules, and of recoiling carbon atoms with aromatic molecules. The reactions of high energy silicon, germanium, and carbon atoms created by nuclear recoil were studied with substrates chosen so that their products illuminated the mechanism of the recoil reactions. Information about the energy and electronic state of the recoiling atoms at reaction was obtained from the variation in end product yields and the extent of decomposition and rearrangement of primary products (usually reactive intermediates) as a function of total pressure and the concentration of inert moderator molecules that remove kinetic energy from the recoiling atoms and can induce transitions between electronic spin states. 29 refs

  17. Silver antimony Ohmic contacts to moderately doped n-type germanium

    Energy Technology Data Exchange (ETDEWEB)

    Dumas, D. C. S.; Gallacher, K.; Millar, R.; Paul, D. J., E-mail: Douglas.Paul@glasgow.ac.uk [School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT (United Kingdom); MacLaren, I. [SUPA School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow G12 8QQ (United Kingdom); Myronov, M.; Leadley, D. R. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2014-04-21

    A self doping contact consisting of a silver/antimony alloy that produces an Ohmic contact to moderately doped n-type germanium (doped to a factor of four above the metal-insulator transition) has been investigated. An evaporation of a mixed alloy of Ag/Sb (99%/1%) onto n-Ge (N{sub D}=1×10{sup 18} cm{sup −3}) annealed at 400 °C produces an Ohmic contact with a measured specific contact resistivity of (1.1±0.2)×10{sup −5} Ω-cm{sup 2}. It is proposed that the Ohmic behaviour arises from an increased doping concentration at the Ge surface due to the preferential evaporation of Sb confirmed by transmission electron microscope analysis. It is suggested that the doping concentration has increased to a level where field emission will be the dominate conduction mechanism. This was deduced from the low temperature electrical characterisation of the contact, which exhibits Ohmic behaviour down to a temperature of 6.5 K.

  18. A dual-PIXE tomography setup for reconstruction of Germanium in ICF target

    Science.gov (United States)

    Guo, N.; Lu, H. Y.; Wang, Q.; Meng, J.; Gao, D. Z.; Zhang, Y. J.; Liang, X. X.; Zhang, W.; Li, J.; Ma, X. J.; Shen, H.

    2017-08-01

    Inertial Confinement Fusion (ICF) is one type of fusion energy research which could initiate nuclear fusion reactions through heating and compressing thermonuclear fuel. Compared to a pure plastic target, Germanium doping into the CH ablator layer by Glow Discharge Polymer (GDP) technique can increase the ablation velocity and the standoff distance between the ablation front and laser-deposition region. During target fabrication process, quantitative doping of Ge should be accurately controlled. Particle Induced X-ray Emission Tomography (PIXE-T) can make not only quantification of the concentration, but also reconstruction of the spatial distribution of doped element. The Si (Li) detector for PIXE tomography technique had a disadvantage of low counting rate. To make up this deficiency, another detector of Si (Li) with the same configuration positioned at the opposite side with the same detective angle 135° have been implemented. Simultaneously acquired elemental maps of Ge obtained using two detectors may be different because of the X-ray absorption along the X-ray exit route in the target. In this paper, the X-ray detection efficiency is drastically improved by this dual-PIXE tomography system.

  19. Indium-hydrogen complexes in silicon and germanium under compression and tension

    International Nuclear Information System (INIS)

    Marx, G.; Vianden, R.

    1996-01-01

    The response of hydrogen-acceptor complexes in silicon and germanium to the application of uniaxial mechanical stress was studied by means of the perturbed angular correlation technique. This hyperfine interaction technique is sensitive to the microscopic structure of the immediate lattice environment of the probe atom. For the measurements, the probe 111 In was introduced into Si and Ge crystals by ion implantation at room temperature. After annealing, the radioactive probe atom 111 In acts as an acceptor in the elemental semiconductors Si and Ge and as such can easily be passivated by hydrogen indiffusion. The resulting In-H complex was subsequently exposed to uniaxial compressive and tensile stress, which was produced by bending the crystals along the three major lattice directions left angle 100 right angle, left angle 110 right angle and left angle 111 right angle. It was found that the application of uniaxial mechanical stress causes no change in the population of the four equivalent bond centred H sites surrounding the In acceptor. Evidence was found for a large mismatch of the lattice parameters between the passivated In implanted layer and the surrounding pure Si. (orig.)

  20. Measurement of low-frequency base and collector current noise and coherence in SiGe heterojunction bipolar transistors using transimpedance amplifiers

    NARCIS (Netherlands)

    Bruce, S.P.O.; Vandamme, L.K.J.; Rydberg, A.

    1999-01-01

    Transimpedance amplifiers have been used for direct study of current noise in silicon germanium (SiGe) heterojunction bipolar transistors (HBT's) at different biasing conditions. This has facilitated a wider range of resistances in the measurement circuit around the transistor than is possible when

  1. Results on decay with emission of two neutrinos or Majorons in Ge from GERDA Phase I

    Science.gov (United States)

    Agostini, M.; Allardt, M.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Barros, N.; Baudis, L.; Bauer, C.; Becerici-Schmidt, N.; Bellotti, E.; Belogurov, S.; Belyaev, S. T.; Benato, G.; Bettini, A.; Bezrukov, L.; Bode, T.; Borowicz, D.; Brudanin, V.; Brugnera, R.; Budjáš, D.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; D'Andrea, V.; Demidova, E. V.; di Vacri, A.; Domula, A.; Doroshkevich, E.; Egorov, V.; Falkenstein, R.; Fedorova, O.; Freund, K.; Frodyma, N.; Gangapshev, A.; Garfagnini, A.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Hegai, A.; Heisel, M.; Hemmer, S.; Heusser, G.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Csáthy, J. Janicskó; Jochum, J.; Junker, M.; Kazalov, V.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Klimenko, A.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lebedev, V. I.; Lehnert, B.; Liao, H. Y.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Majorovits, B.; Maneschg, W.; Medinaceli, E.; Misiaszek, M.; Moseev, P.; Nemchenok, I.; Palioselitis, D.; Panas, K.; Pandola, L.; Pelczar, K.; Pullia, A.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salathe, M.; Schmitt, C.; Schneider, B.; Schönert, S.; Schreiner, J.; Schütz, A.-K.; Schulz, O.; Schwingenheuer, B.; Selivanenko, O.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Stepaniuk, M.; Ur, C. A.; Vanhoefer, L.; Vasenko, A. A.; Veresnikova, A.; von Sturm, K.; Wagner, V.; Walter, M.; Wegmann, A.; Wester, T.; Wilsenach, H.; Wojcik, M.; Yanovich, E.; Zavarise, P.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zuber, K.; Zuzel, G.

    2015-09-01

    A search for neutrinoless decay processes accompanied with Majoron emission has been performed using data collected during Phase I of the GERmanium Detector Array (GERDA) experiment at the Laboratori Nazionali del Gran Sasso of INFN (Italy). Processes with spectral indices were searched for. No signals were found and lower limits of the order of 10 yr on their half-lives were derived, yielding substantially improved results compared to previous experiments with Ge. A new result for the half-life of the neutrino-accompanied decay of Ge with significantly reduced uncertainties is also given, resulting in yr.

  2. Catalyst engineering for lithium ion batteries: the catalytic role of Ge in enhancing the electrochemical performance of SnO2(GeO2)0.13/G anodes.

    Science.gov (United States)

    Zhu, Yun Guang; Wang, Ye; Han, Zhao Jun; Shi, Yumeng; Wong, Jen It; Huang, Zhi Xiang; Ostrikov, Kostya Ken; Yang, Hui Ying

    2014-12-21

    The catalytic role of germanium (Ge) was investigated to improve the electrochemical performance of tin dioxide grown on graphene (SnO(2)/G) nanocomposites as an anode material of lithium ion batteries (LIBs). Germanium dioxide (GeO(20) and SnO(2) nanoparticles (GeO(2))0.13/G nanocomposites can deliver a capacity of 1200 mA h g(-1) at a current density of 100 mA g(-1), which is much higher than the traditional theoretical specific capacity of such nanocomposites (∼ 702 mA h g(-1)). More importantly, the SnO(2)(GeO(2))0.13/G nanocomposites exhibited an improved rate, large current capability (885 mA h g(-1) at a discharge current of 2000 mA g(-1)) and excellent long cycling stability (almost 100% retention after 600 cycles). The enhanced electrochemical performance was attributed to the catalytic effect of Ge, which enabled the reversible reaction of metals (Sn and Ge) to metals oxide (SnO(2) and GeO(2)) during the charge/discharge processes. Our demonstrated approach towards nanocomposite catalyst engineering opens new avenues for next-generation high-performance rechargeable Li-ion batteries anode materials.

  3. Characteristics of an intrinsic germanium detector for measurement of soft x-rays from high-temperature plasmas

    International Nuclear Information System (INIS)

    Kumagai, Katsuaki; Matoba, Tohru; Funahashi, Akimasa; Kawakami, Tomohide

    1976-09-01

    An intrinsic germanium (Ge(I)) detector has been prepared for measurement of soft X-ray spectra from high-temperature tokamak plasmas. Its characteristics of photo-peak efficiency, escape-peak and Compton scattering were calibrated with standard radioisotopes and soft X-rays from the JFT-2a plasma, and compared with those of a lithium-drifted silicon (Si(Li)) detector. Features of the Ge(I) detector are as follows: (i) high detection efficiency in the high energy range, (ii) wide energy range for measurement of soft X-ray spectra, and (iii) low Compton scattering effect in measurement of continuous spectra. Its dead-layer depth is about 0.06μm, and the minimum detectable energies in the Ge(I) detector are similar to those in the Si(Li) detector. The Ge(I) detector is effective for measuring soft X-ray spectra from high-temperature tokamak plasmas. (auth.)

  4. Heteroepitaxial Growth of Germanium-on-Silicon Using Ultrahigh-Vacuum Chemical Vapor Deposition with RF Plasma Enhancement

    Science.gov (United States)

    Alharthi, Bader; Grant, Joshua M.; Dou, Wei; Grant, Perry C.; Mosleh, Aboozar; Du, Wei; Mortazavi, Mansour; Li, Baohua; Naseem, Hameed; Yu, Shui-Qing

    2018-05-01

    Germanium (Ge) films have been grown on silicon (Si) substrate by ultrahigh-vacuum chemical vapor deposition with plasma enhancement (PE). Argon plasma was generated using high-power radiofrequency (50 W) to assist in germane decomposition at low temperature. The growth temperature was varied in the low range of 250°C to 450°C to make this growth process compatible with complementary metal-oxide-semiconductor technology. The material and optical properties of the grown Ge films were investigated. The material quality was determined by Raman and x-ray diffraction techniques, revealing growth of crystalline films in the temperature range of 350°C to 450°C. Photoluminescence spectra revealed improved optical quality at growth temperatures of 400°C and 450°C. Furthermore, material quality study using transmission electron microscopy revealed existence of defects in the Ge layer grown at 400°C. Based on the etch pit density, the average threading dislocation density in the Ge layer obtained at this growth temperature was measured to be 4.5 × 108 cm-2. This result was achieved without any material improvement steps such as use of graded buffer or thermal annealing. Comparison between PE and non-plasma-enhanced growth, in the same machine at otherwise the same growth conditions, indicated increased growth rate and improved material and optical qualities for PE growth.

  5. Broadband and wide-angle distributed Bragg reflectors based on amorphous germanium films by glancing angle deposition.

    Science.gov (United States)

    Leem, Jung Woo; Yu, Jae Su

    2012-08-27

    We fabricated the distributed Bragg reflectors (DBRs) with amorphous germanium (a-Ge) films consisted of the same materials at a center wavelength (λc) of 1.33 μm by the glancing angle deposition. Their optical reflectance properties were investigated in the infrared wavelength region of 1-1.9 μm at incident light angles (θ inc) of 8-70°, together with the theoretical analysis using a rigorous coupled-wave analysis simulation. The two alternating a-Ge films at the incident vapor flux angles of 0 and 75° were formed as the high and low refractive index materials, respectively. The a-Ge DBR with only 5 periods exhibited a normalized stop bandwidth (∆λ/λ c) of ~24.1%, maintaining high reflectance (R) values of > 99%. Even at a high θ inc of 70°, the ∆λ/λ c was ~21.9%, maintaining R values of > 85%. The a-Ge DBR with good uniformity was obtained over the area of a 2 inch Si wafer. The calculated reflectance results showed a similar tendency to the measured data.

  6. Room temperature lasing unraveled by a strong resonance between gain and parasitic absorption in uniaxially strained germanium

    Science.gov (United States)

    Gupta, Shashank; Nam, Donguk; Vuckovic, Jelena; Saraswat, Krishna

    2018-04-01

    A complementary metal-oxide semiconductor compatible on-chip light source is the holy grail of silicon photonics and has the potential to alleviate the key scaling issues arising due to electrical interconnects. Despite several theoretical predictions, a sustainable, room temperature laser from a group-IV material is yet to be demonstrated. In this work, we show that a particular loss mechanism, inter-valence-band absorption (IVBA), has been inadequately modeled until now and capturing its effect accurately as a function of strain is crucial to understanding light emission processes from uniaxially strained germanium (Ge). We present a detailed model of light emission in Ge that accurately models IVBA in the presence of strain and other factors such as polarization, doping, and carrier injection, thereby revising the road map toward a room temperature Ge laser. Strikingly, a special resonance between gain and loss mechanisms at 4%-5% 〈100 〉 uniaxial strain is found resulting in a high net gain of more than 400 cm-1 at room temperature. It is shown that achieving this resonance should be the goal of experimental work rather than pursuing a direct band gap Ge.

  7. Uranium enrichment

    International Nuclear Information System (INIS)

    1991-11-01

    This paper analyzes under four different scenarios the adequacy of a $500 million annual deposit into a fund to pay for the cost of cleaning up the Department of Energy's (DOE) three aging uranium enrichment plants. These plants are located in Oak Ridge, Tennessee; Paducah, Kentucky; and Portsmouth, Ohio. In summary the following was found: A fixed annual $500 million deposit made into a cleanup fund would not be adequate to cover total expected cleanup costs, nor would it be adequate to cover expected decontamination and decommissioning (D and D) costs. A $500 million annual deposit indexed to an inflation rate would likely be adequate to pay for all expected cleanup costs, including D and D costs, remedial action, and depleted uranium costs

  8. Silicon germanium as a novel mask for silicon deep reactive ion etching

    KAUST Repository

    Serry, Mohamed Y.

    2013-10-01

    This paper reports on the use of p-type polycrystalline silicon germanium (poly-Si1-xGex) thin films as a new masking material for the cryogenic deep reactive ion etching (DRIE) of silicon. We investigated the etching behavior of various poly-Si1-xGex:B (0Ge mask for silicon depends strongly on three factors: Ge content; boron concentration; and etching temperature. Compared to conventional SiO2 and SiN masks, the proposed SiGe masking material exhibited several advantages, including high etching selectivity to silicon (>1:800). Furthermore, the SiGe mask was etched in SF6/O2 plasma at temperatures ≥ - 80°C and at rates exceeding 8 μm/min (i.e., more than 37 times faster than SiO2 or SiN masks). Because of the chemical and thermodynamic stability of the SiGe film as well as the electronic properties of the mask, it was possible to deposit the proposed film at CMOS backend compatible temperatures. The paper also confirms that the mask can easily be dry-removed after the process with high etching-rate by controlling the ICP and RF power and the SF6 to O2 ratios, and without affecting the underlying silicon substrate. Using low ICP and RF power, elevated temperatures (i.e., > - 80°C), and an adjusted O2:SF6 ratio (i.e., ~6%), we were able to etch away the SiGe mask without adversely affecting the final profile. Ultimately, we were able to develop deep silicon- trenches with high aspect ratio etching straight profiles. © 1992-2012 IEEE.

  9. Eiperimental and thermodynamic study od curve of retrograde solidus in InP-Ge quasi-binary system

    International Nuclear Information System (INIS)

    Glazov, V.M.; Pavlova, L.M.; Perederij, L.I.

    1983-01-01

    Germanium solubility in indium phosphide at different temperatures is experimentally investigated, and it is shown that the solidus curve in the portion adjoining InP is of a retrograde character. The method of radioactive tracers has been used to determine the coefficient of germanium distribution between the liquid and solid phases at a melting point of indium phosphide. Concentration dependence of the number of electrons at indium phosphide doping with germanium is investigated, and violation of the ionization equality is shown that is explained by an amphoteric character of o.ermanium behaviour in the InP base solid solution resulting in a self-compensation effect. The retrograde solidus curve in the InP-Ge system is calculated thermodynamically with the use of model representations on the composition of solid and liquid solutions. The ionization degree of doping impurity and self-compensation effect are taken account in calculation. Good agreement of the calculated and experimental data is observed

  10. Ge{sup 4+} doped TiO{sub 2} for stoichiometric degradation of warfare agents

    Energy Technology Data Exchange (ETDEWEB)

    Stengl, Vaclav, E-mail: stengl@iic.cas.cz [Department of Solid State Chemistry, Institute of Inorganic Chemistry AS CR v.v.i., 250 68 Rez (Czech Republic); Grygar, Tomas Matys [Department of Solid State Chemistry, Institute of Inorganic Chemistry AS CR v.v.i., 250 68 Rez (Czech Republic); Oplustil, Frantisek; Nemec, Tomas [Military Technical Institute of Protection Brno, Veslarska 230, 628 00 Brno (Czech Republic)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer We prepared nanodisperse Ge{sup 4+} doped titania by a novel synthesis method. Black-Right-Pointing-Pointer Synthesis does not involve organic solvents, organometallics nor thermal processes. Black-Right-Pointing-Pointer The prepared materials are efficient in removal of chemical warfare agents. Black-Right-Pointing-Pointer Ge{sup 4+} doping improves rate of removal of soman and agent VX by TiO{sub 2}. - Abstract: Germanium doped TiO{sub 2} was prepared by homogeneous hydrolysis of aqueous solutions of GeCl{sub 4} and TiOSO{sub 4} with urea. The synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, EDS analysis, specific surface area (BET) and porosity determination (BJH). Ge{sup 4+} doping increases surface area and content of amorphous phase in prepared samples. These oxides were used in an experimental evaluation of their reactivity with chemical warfare agent, sulphur mustard, soman and agent VX. Ge{sup 4+} doping worsens sulphur mustard degradation and improves soman and agent VX degradation. The best degree of removal (degradation), 100% of soman, 99% of agent VX and 95% of sulphur mustard, is achieved with sample with 2 wt.% of germanium.

  11. Modeling of dislocation dynamics in germanium Czochralski growth

    Science.gov (United States)

    Artemyev, V. V.; Smirnov, A. D.; Kalaev, V. V.; Mamedov, V. M.; Sidko, A. P.; Podkopaev, O. I.; Kravtsova, E. D.; Shimansky, A. F.

    2017-06-01

    Obtaining very high-purity germanium crystals with low dislocation density is a practically difficult problem, which requires knowledge and experience in growth processes. Dislocation density is one of the most important parameters defining the quality of germanium crystal. In this paper, we have performed experimental study of dislocation density during 4-in. germanium crystal growth using the Czochralski method and comprehensive unsteady modeling of the same crystal growth processes, taking into account global heat transfer, melt flow and melt/crystal interface shape evolution. Thermal stresses in the crystal and their relaxation with generation of dislocations within the Alexander-Haasen model have been calculated simultaneously with crystallization dynamics. Comparison to experimental data showed reasonable agreement for the temperature, interface shape and dislocation density in the crystal between calculation and experiment.

  12. Significant reduction of thermal conductivity in Si/Ge core-shell nanowires.

    Science.gov (United States)

    Hu, Ming; Giapis, Konstantinos P; Goicochea, Javier V; Zhang, Xiaoliang; Poulikakos, Dimos

    2011-02-09

    We report on the effect of germanium (Ge) coatings on the thermal transport properties of silicon (Si) nanowires using nonequilibrium molecular dynamics simulations. Our results show that a simple deposition of a Ge shell of only 1 to 2 unit cells in thickness on a single crystalline Si nanowire can lead to a dramatic 75% decrease in thermal conductivity at room temperature compared to an uncoated Si nanowire. By analyzing the vibrational density states of phonons and the participation ratio of each specific mode, we demonstrate that the reduction in the thermal conductivity of Si/Ge core-shell nanowire stems from the depression and localization of long-wavelength phonon modes at the Si/Ge interface and of high frequency nonpropagating diffusive modes.

  13. Ge nanocrystals embedded in ultrathin Si3N4 multilayers with SiO2 barriers

    Science.gov (United States)

    Bahariqushchi, R.; Gundogdu, Sinan; Aydinli, A.

    2017-04-01

    Multilayers of germanium nanocrystals (NCs) embedded in thin films of silicon nitride matrix separated with SiO2 barriers have been fabricated using plasma enhanced chemical vapor deposition (PECVD). SiGeN/SiO2 alternating bilayers have been grown on quartz and Si substrates followed by post annealing in Ar ambient from 600 to 900 °C. High resolution transmission electron microscopy (HRTEM) as well as Raman spectroscopy show good crystallinity of Ge confined to SiGeN layers in samples annealed at 900 °C. Strong compressive stress for SiGeN/SiO2 structures were observed through Raman spectroscopy. Size, as well as NC-NC distance were controlled along the growth direction for multilayer samples by varying the thickness of bilayers. Visible photoluminescence (PL) at 2.3 and 3.1 eV with NC size dependent intensity is observed and possible origin of PL is discussed.

  14. SiGe-based re-engineering of electronic warfare subsystems

    CERN Document Server

    Lambrechts, Wynand

    2017-01-01

    This book equips readers with a thorough understanding of the applicability of new-generation silicon-germanium (SiGe) electronic subsystems for the military purposes of electronic warfare and defensive countermeasures. The theoretical and technical background is extensively explained and all aspects of the integration of SiGe as an enabling technology for maritime, land, and airborne (including space) electronic warfare are addressed, including research, design, development, and implementation. The coverage is supported by mathematical derivations, informative illustrations, practical examples, and case studies. While SiGe technology provides speed, performance, and price advantages in many markets, sharing of information on its use in electronic warfare systems has to date been limited, especially in developing nations. This book will therefore be warmly welcomed as an engineering guideline that focuses especially on the speed and reliability of current-generation SiGe circuits and highlights emerging innov...

  15. Ultra-Pure Water and Extremophilic Bacteria interactions with Germanium Surfaces

    Science.gov (United States)

    Sah, Vasu R.

    Supported by a consortium of semiconductor industry sponsors, an international "TIE" project among 5 National Science Foundation (NSF) Industry/university Cooperative Research Centers discovered that a particular extremophilic microbe, Pseudomonas syzygii, persists in the UltraPure Water (UPW) supplies of chip fabrication facilities (FABs) and can bio-corrode germanium wafers to produce microbe-encased optically transparent crystals. Considered as potentially functional "biochips", this investigation explored mechanisms for the efficient and deliberate production of such microbe-germania adducts as a step toward later testing of their properties as sensors or switches in bioelectronic or biophotonic circuits. Recirculating UPW (Ultra-Pure Water) and other purified water, laminar-flow loops were developed across 50X20x1mm germanium (Ge) prisms, followed by subsequent examination of the prism surfaces using Multiple Attenuated Internal Reflection InfraRed (MAIR-IR) spectroscopy, Contact Potential measurements, Differential Interference Contrast Light Microscopy (DICLM), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDS), and Electron Spectroscopy for Chemical Analysis (ESCA; XPS). P. syzygii cultures originally obtained from a working FAB at University of Arizona were successfully grown on R2A minimal nutrient media. They were found to be identical to the microbes in stored UPW from the same facility, such microbes routinely capable of nucleation and entrapment within GeO2 crystals on the Ge flow surfaces. Optimum flow rates and exposure times were 1 ml/minute (3.2 s-1 shear rate) for 4 days at room temperature, producing densest crystal arrays at the prism central zones 2-3 cm from the flow inlets. Other flow rates and exposure times have higher shear rate which induces a different nucleation mechanism and saturation of crystal formation. Nucleation events began with square and circular oxide deposits surrounding active attached bacteria

  16. Niobium nitride Josephson junctions with silicon and germanium barriers

    International Nuclear Information System (INIS)

    Cukauskas, E.J.; Carter, W.L.

    1988-01-01

    Niobium nitride based junctions with silicon, germanium, and composite silicon/germanium barriers were fabricated and characterized for several barrier compositions. The current-voltage characteristics were analyzed at several temperatures using the Simmons model and numerical integration of the WKB approximation for the average barrier height and effective thickness. The zero voltage conductance was measured from 1.5 K to 300 K and compared to the Mott hopping conductivity model and the Stratton tunneling temperature dependence. Conductivity followed Mott conductivity at temperatures above 60 K for junctions with less than 100 angstrom thick barriers

  17. Characterisation of two AGATA asymmetric high purity germanium capsules

    International Nuclear Information System (INIS)

    Colosimo, S.J.; Moon, S.; Boston, A.J.; Boston, H.C.; Cresswell, J.R.; Harkness-Brennan, L.; Judson, D.S.; Lazarus, I.H.; Nolan, P.J.; Simpson, J.; Unsworth, C.

    2015-01-01

    The AGATA spectrometer is an array of highly segmented high purity germanium detectors. The spectrometer uses pulse shape analysis in order to track Compton scattered γ-rays to increase the efficiency of nuclear spectroscopy studies. The characterisation of two high purity germanium detector capsules for AGATA of the same A-type has been performed at the University of Liverpool. This work will examine the uniformity of performance of the two capsules, including a comparison of the resolution and efficiency as well as a study of charge collection. The performance of the capsules shows good agreement, which is essential for the efficient operation of the γ-ray tracking array

  18. Characterisation of two AGATA asymmetric high purity germanium capsules

    Energy Technology Data Exchange (ETDEWEB)

    Colosimo, S.J., E-mail: sjc@ns.ph.liv.ac.uk [Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Moon, S.; Boston, A.J.; Boston, H.C.; Cresswell, J.R.; Harkness-Brennan, L.; Judson, D.S. [Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Lazarus, I.H. [STFC Daresbury, Daresbury, Warrington WA4 4AD (United Kingdom); Nolan, P.J. [Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Simpson, J. [STFC Daresbury, Daresbury, Warrington WA4 4AD (United Kingdom); Unsworth, C. [Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE (United Kingdom)

    2015-02-11

    The AGATA spectrometer is an array of highly segmented high purity germanium detectors. The spectrometer uses pulse shape analysis in order to track Compton scattered γ-rays to increase the efficiency of nuclear spectroscopy studies. The characterisation of two high purity germanium detector capsules for AGATA of the same A-type has been performed at the University of Liverpool. This work will examine the uniformity of performance of the two capsules, including a comparison of the resolution and efficiency as well as a study of charge collection. The performance of the capsules shows good agreement, which is essential for the efficient operation of the γ-ray tracking array.

  19. Quantitative spectrographic determination of traces of germanium in lignite

    International Nuclear Information System (INIS)

    Martin, M.; Roca, M.

    1972-01-01

    A burning technique in a d.c. arc at 10 amp has been employed. The standards have been prepared from a natural lignite with a low germanium content. In order to enhance sensitivity, AgCl, K 2 SO 4 , CuF 2 , Sb 2 S 3 and Bi 2 S 3 have been tested as sweeping materials. Using 2% CuF 2 a detection limit of 1 ppm germanium is attainable. Bi, Cu, Sb and Sn have been studied as internal standards: the former leads to the, highest precision (1 6%. Results show good agreement with those obtained by the addition method. (Author) 6 refs

  20. Program LEPS to addition of gamma spectra from germanium detectors

    International Nuclear Information System (INIS)

    Romero, L.

    1986-01-01

    The LEP program, written in FORTRAN IV, performs the addition of two spectra, collected with different detectors, from the same sample. This application, adds the two gamma spectra obtained from two opposite LEPS Germanium Detectors (Low Energy Photon Spectrometer), correcting the differences (channel/energy) between both two spectra, and fitting them before adding. The total-spectrum is recorded at the computer memory as a single spectrum. The necessary equipment, to run this program is: - Two opposite germanium detectors, with their associate electronics. - Multichannel analyzer (2048 memory channel minimum) - Computer on-line interfacing to multichannel analyzer. (Author) 4 refs

  1. Effects of germane flow rate in electrical properties of a-SiGe:H films for ambipolar thin-film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez, Miguel, E-mail: madominguezj@gmail.com [Centro de Investigaciones en Dispositivos Semiconductores, Instituto de Ciencias, Benemerita Universidad Autonoma de Puebla (BUAP), Puebla 72570 (Mexico); Rosales, Pedro, E-mail: prosales@inaoep.mx [National Institute for Astrophysics, Optics and Electronics (INAOE), Electronics Department, Luis Enrique Erro No. 1, Puebla 72840 (Mexico); Torres, Alfonso [National Institute for Astrophysics, Optics and Electronics (INAOE), Electronics Department, Luis Enrique Erro No. 1, Puebla 72840 (Mexico); Flores, Francisco [Centro de Investigaciones en Dispositivos Semiconductores, Instituto de Ciencias, Benemerita Universidad Autonoma de Puebla (BUAP), Puebla 72570 (Mexico); Molina, Joel; Moreno, Mario [National Institute for Astrophysics, Optics and Electronics (INAOE), Electronics Department, Luis Enrique Erro No. 1, Puebla 72840 (Mexico); Luna, Jose [Centro de Investigaciones en Dispositivos Semiconductores, Instituto de Ciencias, Benemerita Universidad Autonoma de Puebla (BUAP), Puebla 72570 (Mexico); Orduña, Abdu [Centro de Investigación en Biotecnología Aplicada (CIBA), IPN, Tlaxcala, Tlaxcala 72197 (Mexico)

    2014-07-01

    In this work, the study of germane flow rate in electrical properties of a-SiGe:H films is presented. The a-SiGe:H films deposited by low frequency plasma-enhanced chemical vapor deposition at 300 °C were characterized by Fourier transform infrared spectroscopy, measurements of temperature dependence of conductivity and UV–visible spectroscopic ellipsometry. After finding the optimum germane flow rate conditions, a-SiGe:H films were deposited at 200 °C and analyzed. The use of a-SiGe:H films at 200 °C as active layer of low-temperature ambipolar thin-film transistors (TFTs) was demonstrated. The inverted staggered a-SiGe:H TFTs with Spin-On Glass as gate insulator were fabricated. These results suggest that there is an optimal Ge content in the a-SiGe:H films that improves its electrical properties. - Highlights: • As the GeH{sub 4} flow rate increases the content of oxygen decreases. • Ge-H bonds show the highest value in a-SiGe:H films with GeH{sub 4} flow of 105 sccm. • Films with GeH{sub 4} flow of 105 sccm show the highest activation energy. • An optimum incorporation of germanium is obtained with GeH{sub 4} flow rate of 105 sccm. • At 200 °C the optimum condition of the a-SiGe:H films remain with no changes.

  2. GeO2 Thin Film Deposition on Graphene Oxide by the Hydrogen Peroxide Route: Evaluation for Lithium-Ion Battery Anode.

    Science.gov (United States)

    Medvedev, Alexander G; Mikhaylov, Alexey A; Grishanov, Dmitry A; Yu, Denis Y W; Gun, Jenny; Sladkevich, Sergey; Lev, Ovadia; Prikhodchenko, Petr V

    2017-03-15

    A peroxogermanate thin film was deposited in high yield at room temperature on graphene oxide (GO) from peroxogermanate sols. The deposition of the peroxo-precursor onto GO and the transformations to amorphous GeO 2 , crystalline tetragonal GeO 2 , and then to cubic elemental germanium were followed by electron microscopy, XRD, and XPS. All of these transformations are influenced by the GO support. The initial deposition is explained in view of the sol composition and the presence of GO, and the different thermal transformations are explained by reactions with the graphene support acting as a reducing agent. As a test case, the evaluation of the different materials as lithium ion battery anodes was carried out revealing that the best performance is obtained by amorphous germanium oxide@GO with >1000 mAh g -1 at 250 mA g -1 (between 0 and 2.5 V vs Li/Li + cathode), despite the fact that the material contained only 51 wt % germanium. This is the first demonstration of the peroxide route to produce peroxogermanate thin films and thereby supported germanium and germanium oxide coatings. The advantages of the process over alternative methodologies are discussed.

  3. Low Temperature (180°C Growth of Smooth Surface Germanium Epilayers on Silicon Substrates Using Electron Cyclotron Resonance Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Teng-Hsiang Chang

    2014-01-01

    Full Text Available This paper describes a new method to grow thin germanium (Ge epilayers (40 nm on c-Si substrates at a low growth temperature of 180°C using electron cyclotron resonance chemical vapor deposition (ECR-CVD process. The full width at half maximum (FWHM of the Ge (004 in X-ray diffraction pattern and the compressive stain in a Ge epilayer of 683 arcsec and 0.12% can be achieved. Moreover, the Ge/Si interface is observed by transmission electron microscopy to demonstrate the epitaxial growth of Ge on Si and the surface roughness is 0.342 nm. The thin-thickness and smooth surface of Ge epilayer grown on Si in this study is suitable to be a virtual substrate for developing the low cost and high efficiency III-V/Si tandem solar cells in our opinion. Furthermore, the low temperature process can not only decrease costs but can also reduce the restriction of high temperature processes on device manufacturing.

  4. Atomic layer deposition of GeO{sub 2} thin films on Si(100) using Ge(N,N'-R,R-en)(NMe{sub 2}){sub 2} (where R = Isopropyl and t-Butyl) precursors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae Hyun; Shin, Jin Ho [Soulbrain Sigma-Aldrich Co., Ltd., Gongju (Korea, Republic of); Jung, Jae Sun; Kang, Jun Gill [Chungnam National University, Daejeon (Korea, Republic of)

    2015-08-15

    In this study, we introduced bis(dimethylamino)(N,N'-diisopropyl-ethylenediamine) germanium (1) and bis (dimethyl-amino)(N,N'-di-tert-butyl-ethylenediamine) germanium (2) as novel ALD precursors and analyzed the ALD growth characteristics to obtain the best possible film properties. A 5-L three-neck flask was charged with 2.5 L of toluene, GeCl{sub 4} (60 g, 0.28 mol) was added and then cooled to -15 to -20 .deg. C. the two precursors produced good-quality GeO{sub 2} thin films via the ALD process. The ALD windows of bis(dimethylamino)(N,N'-di-isopropyl-ethylenediamine) germanium and bis(dimethylamino)(N,N'-di-tert -butyl-ethylene-diamine) germanium were established at 200–330 .deg. C with a growth rate of about 0.40 and 0.31 Å/cycle, respectively. ALD-type growth mode was verified by increasing the precursor pulsing time. Growth rate was saturated from 3.0 s. These films have considerable potential for industrial applications.

  5. Production of a 68Ge/68Ga generator

    International Nuclear Information System (INIS)

    Behrouz Shirazi; Behrouz Fateh; Mohammad Mirzaii; Gholamreza Aslani

    2004-01-01

    Background: Gallium-68 is a radioisotope with a half life of 68 min. As it has a specific decay mode, it is a positron emitter and hence, it is popularly used in nuclear medicine. The only way to obtain these nuclides is to produced the mother nuclease which is Germanium - 68. There are many nuclear reactions from which the Germanium - 68 is obtained, however, the best reaction is 69Ga (p,2n)68Ge. Materials and Methods: The cross section of this nuclear reaction was calculated with the ALICE-91 Code and the result was compared with the practical work done by other researchers. The comparing result was an acceptable one. Having the cross sections in mind, the best proton energy was calculated to be between 20-25 MeV Further research showed that Ga2O3 is the best type of target material. Therefore, it was necessary to design and make a suitable target holder for these k/nd of compositions, which for the very first time in Iran was done at Atomic Energy Organization of Iran (AEOI). The thickness of the target, bearing in mind the rate of energy loss in side the target material, was calculated with the SRIM Code and the Ga2O3 tablets were made with FT-IR instruments at Nuclear Research Center for Agriculture and Medicine (NRCAM). They were then bombarded with the 20, 21 and 22.5 MeV proton energy and the beam currents of 1.4, 7.5 and 13.3 μA.Two weeks after the bombardment the radio chemical separation of Germanium - 68 was done with concentrated acid HNO3 and applying heat. Then, the acid solution was evaporated till dried, after that, an EDTA solution (0.005 M, pH = 11) was added to recover the Germanium - 68. By passing the EDTA solution through the A12O3 column, Germanium - 68 radioisotope was adsorbed.Then another solution of EDTA (0.005 M, PH=11) was passed thorough the loaded column, almost all the natural Gallium impurities were removed.In this project the behavior of natural Gallium was studied via adding Gallium-67 as a tracer which it's half life is about

  6. Local atomic structure and chemical order in amorphous SiGe:H and SiC:H alloys

    International Nuclear Information System (INIS)

    Pisarkiewicz, T.; Stapinski, T.

    1994-01-01

    The local structure and chemical ordering in amorphous hydrogenated silicon-germanium and silicon-carbon alloys were analyzed mainly with the help of extended x-ray absorption fine structure (EXAFS) spectroscopy, Raman scattering and electron diffraction. Ge-Ge and Ge-Si distances were found to be independent of concentration and the composition of the first coordination shell around Ge is consistent with a random mixing of the two species in a-Si 1-x Ge:H alloy. The first-coordination-shell average bond lengths for Si-Si and SiC in a-Si 1-x C x :H are also constant with concentration x and the comparison of the first coordination shell composition around Si with average concentration indicates that the alloys tends to be chemically ordered. The degree of crystallinity in microcrystalline Si films determined by EXAFS is in agreement with that obtained in Raman scattering analysis. (author). 16 refs, 5 figs

  7. Spectroscopic characterization of germanium quantum dots in silicon; Spektroskopische Charakterisierung von Germanium-Quantenpunkten in Silizium

    Energy Technology Data Exchange (ETDEWEB)

    Bougeard, D.

    2006-01-15

    This thesis presents the first detailed investigation of the phonon Raman spectrum of Ge hut clusters. Interpretations of Ge/Si superlattice and SiGe alloy spectra are successfully adapted to the quantum dot spectrum. The period, the sublayers of a period, as well as biaxial strain are determined through the analysis of the acoustic phonons which propagate through the whole multilayer structure. At the same time, the non dispersing optical phonons are localised in the single layers of the structure. Thus they act as local sensors probing the average composition, the strain field and the mode localisation energy in one particular type of layer in the period. The frequency positions and relative intensities of the characteristical vibration mode are discussed in detail. Ex-situ annealing above 600 C is also studied with Raman phonon scattering. The annealing leads to an increase of the island volume and substantial intermixing, which is characterised through the determination of the interdiffusion constants. The investigation of optical transitions in Ge/Si multilayer structures shows quantum dot-like behaviour for the Ge hut clusters. Photoluminescence spectra show only phononless recombinations of electron-hole pairs for the hut clusters. Photocurrent spectroscopy reveals a localisation energy of 380 meV for the dot ground level compared to the Si valence band edge. Optical transitions between bound states in the quantum dots and potential minima in the Ge wetting layer or the neighbouring (2 nm) modulation doping layer, are observed through the spectral analysis of the photoconductivity in the quantum dot plane. The energy difference between these minima and the Si valence band edge is 40 meV. Finally resonant electronic Raman scattering reveals an optical intraband transition with an energy difference of 105 meV between initial and final transition state. (orig.)

  8. Active noise canceling system for mechanically cooled germanium radiation detectors

    Science.gov (United States)

    Nelson, Karl Einar; Burks, Morgan T

    2014-04-22

    A microphonics noise cancellation system and method for improving the energy resolution for mechanically cooled high-purity Germanium (HPGe) detector systems. A classical adaptive noise canceling digital processing system using an adaptive predictor is used in an MCA to attenuate the microphonics noise source making the system more deployable.

  9. Direct observations of the vacancy and its annealing in germanium

    DEFF Research Database (Denmark)

    Slotte, J.; Kilpeläinen, S.; Tuomisto, F.

    2011-01-01

    Weakly n-type doped germanium has been irradiated with protons up to a fluence of 3×1014 cm-2 at 35 K and 100 K in a unique experimental setup. Positron annihilation measurements show a defect lifetime component of 272±4 ps at 35 K in in situ positron lifetime measurements after irradiation at 100...

  10. Dislocation multiplication rate in the early stage of germanium plasticity

    Czech Academy of Sciences Publication Activity Database

    Fikar, J.; Dupas, Corinne; Kruml, Tomáš; Jacques, A.; Martin, J. L.

    400-401, - (2005), s. 431-434 ISSN 0921-5093. [Dislocations 2004. La Colle-sur-Loup, 13.09.2004-17.09.2004] Institutional research plan: CEZ:AV0Z2041904 Keywords : dislocation multiplication * germanium * constitutive modelling Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.347, year: 2005

  11. Effect of normal processes on thermal conductivity of germanium ...

    Indian Academy of Sciences (India)

    Abstract. The effect of normal scattering processes is considered to redistribute the phonon momentum in (a) the same phonon branch – KK-S model and (b) between differ- ent phonon branches – KK-H model. Simplified thermal conductivity relations are used to estimate the thermal conductivity of germanium, silicon and ...

  12. Composite germanium monochromators - results for the TriCS

    Energy Technology Data Exchange (ETDEWEB)

    Schefer, J.; Fischer, S.; Boehm, M.; Keller, L.; Horisberger, M.; Medarde, M.; Fischer, P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    Composite germanium monochromators are in the beginning of their application in neutron diffraction. We show here the importance of the permanent quality control with neutrons on the example of the 311 wafers which will be used on the single crystal diffractometer TriCS at SINQ. (author) 2 figs., 3 refs.

  13. Development of revitalisation technique for impaired lithium doped germanium detector

    International Nuclear Information System (INIS)

    Singh, N.S.B.; Rafi Ahmed, A.G.; Balasubramanian, G.R.

    1994-01-01

    Semiconductor detectors play very significant role in photon detection and are important tools in the field of gamma spectroscopy. Lithium doped germanium detectors belong to this category. The development of revitalisation technique for these impaired detectors are discussed in this report

  14. Comparative analysis of germanium-silicon quantum dots formation on Si(100), Si(111) and Sn/Si(100) surfaces

    Science.gov (United States)

    Lozovoy, Kirill; Kokhanenko, Andrey; Voitsekhovskii, Alexander

    2018-02-01

    In this paper theoretical modeling of formation and growth of germanium-silicon quantum dots in the method of molecular beam epitaxy (MBE) on different surfaces is carried out. Silicon substrates with crystallographic orientations (100) and (111) are considered. Special attention is paid to the question of growth of quantum dots on the silicon surface covered by tin, since germanium-silicon-tin system is extremely important for contemporary nano- and optoelectronics: for creation of photodetectors, solar cells, light-emitting diodes, and fast-speed transistors. A theoretical approach for modeling growth processes of such semiconductor compounds during the MBE is presented. Both layer-by-layer and island nucleation stages in the Stranski-Krastanow growth mode are described. A change in free energy during transition of atoms from the wetting layer to an island, activation barrier of the nucleation, critical thickness of 2D to 3D transition, as well as surface density and size distribution function of quantum dots in these systems are calculated with the help of the established model. All the theoretical speculations are carried out keeping in mind possible device applications of these materials. In particular, it is theoretically shown that using of the Si(100) surface covered by tin as a substrate for Ge deposition may be very promising for increasing size homogeneity of quantum dot array for possible applications in low-noise selective quantum dot infrared photodetectors.

  15. Combined experimental and ab-initio investigation of the physical properties of Ni{sub 3}Ge and Ni{sub 3}Al

    Energy Technology Data Exchange (ETDEWEB)

    Dinkel, Markus; Janisch, Rebecca; Pyczak, Florian; Goeken, Mathias [Institute General Materials Properties, University Erlangen-Nuernberg, Erlangen (Germany)

    2008-07-01

    Germanium is a promising element for brazing alloys to repair single crystalline ni-base superalloys. Germanium has the advantage that it forms an ordered Ni{sub 3}Ge phase with the same crystal structure as Ni{sub 3}Al ({gamma}' phase). The {gamma}' phase is responsible for the excellent mechanical properties of Ni-base superalloys at high temperature. Interdiffusion between the braze and the base material causes a decreasing concentration of germanium from the brazing zone to the base material and vice versa for aluminum. In the {gamma}' precipitates germanium is more and more substituted by aluminum, which should lead to changing properties of the {gamma}' phase between brazing zone center and base material. In our investigations we determined the chemical composition of binary Ni-Ge by energy dispersive spectroscopy in the electron microscope, the lattice constants using X-ray diffraction investigated the mechanical properties by nanoindentation in an atomic force microscope. Additionally, equilibrium lattice constants, energies of formation, bulk moduli and defect energies of pure Ni{sub 3}Ge and Ni{sub 3}Al phases were calculated by means of a spin-polarized ab initio density-functional method in the general-gradient approximation. The results are discussed in the light of the experimental data.

  16. Tunable conduction type of solution-processed germanium nanoparticle based field effect transistors and their inverter integration.

    Science.gov (United States)

    Meric, Zeynep; Mehringer, Christian; Karpstein, Nicolas; Jank, Michael P M; Peukert, Wolfgang; Frey, Lothar

    2015-09-14

    In this work we demonstrate the fabrication of germanium nanoparticle (NP) based electronics. The whole process chain from the nanoparticle production up to the point of inverter integration is covered. Ge NPs with a mean diameter of 33 nm and a geometric standard deviation of 1.19 are synthesized in the gas phase by thermal decomposition of GeH4 precursor in a seeded growth process. Dispersions of these particles in ethanol are employed to fabricate thin particulate films (60 to 120 nm in thickness) on substrates with a pre-patterned interdigitated aluminum electrode structure. The effect of temperature treatment, polymethyl methacrylate encapsulation and alumina coating by plasma-assisted atomic layer deposition (employing various temperatures) on the performance of these layers as thin film transistors (TFTs) is investigated. This coating combined with thermal annealing delivers ambipolar TFTs which show an Ion/Ioff ratio in the range of 10(2). We report fabrication of n-type, p-type or ambipolar Ge NP TFTs at maximum temperatures of 450 °C. For the first time, a circuit using two ambipolar TFTs is demonstrated to function as a NOT gate with an inverter gain of up to 4 which can be operated at room temperature in ambient air.

  17. The M-band transmission flux of the plastic foil with a coated layer of silicon or germanium

    International Nuclear Information System (INIS)

    Li, Liling; Zhang, Lu; Jiang, Shaoen; Guo, Liang; Qing, Bo; Li, Zhichao; Zhang, Jiyan; Yang, Jiamin; Ding, Yongkun

    2014-01-01

    Silicon (Si) and Germanium (Ge) can be used as the dopant in the ablator material for the purpose of reducing preheating in indirect-drive inertial confinement fusion. Their performances in reducing preheating are quite different. A method to evaluate the difference of these two kinds of dopants has been presented in this letter. In the Shenguang-II high power laser facility, the M-band (1.6–4.4 keV) transmission flux of Si-coated plastic (CH) and Ge-coated plastic (CH) has been measured by using the M-band x-ray diode. In the experiment, we find that the Si-coated CH can absorb more M-band x-rays and thus reduce the preheating of the fuel in our experiment condition. By using the radiation hydrodynamic code MULTI-1D, we got the simulation result which was well suited for the experiment. The comparison of their opacities (T e = 60–100 eV and ρ = 0.1–0.5 g/cm 3 ) also shows that the opacity of Si is higher than that of Ge almost in the whole range of 1.6–4.4 keV

  18. Comparison of cross-sectional transmission electron microscope studies of thin germanium epilayers grown on differently oriented silicon wafers.

    Science.gov (United States)

    Norris, D J; Myronov, M; Leadley, D R; Walther, T

    2017-12-01

    We compare transmission electron microscopical analyses of the onset of islanding in the germanium-on-silicon (Ge/Si) system for three different Si substrate orientations: (001), (11¯0) and (11¯1)Si. The Ge was deposited by reduced pressure chemical vapour deposition and forms islands on the surface of all Si wafers; however, the morphology (aspect ratio) of the deposited islands is different for each type of wafer. Moreover, the mechanism for strain relaxation is different for each type of wafer owing to the different orientation of the (111) slip planes with the growth surface. Ge grown on (001)Si is initially pseudomorphically strained, yielding small, almost symmetrical islands of high aspect ratio (clusters or domes) on top interdiffused SiGe pedestals, without any evidence of plastic relaxation by dislocations, which would nucleate later-on when the islands might have coalesced and then the Matthews-Blakeslee limit is reached. For (11¯0)Si, islands are flatter and more asymmetric, and this is correlated with plastic relaxation of some islands by dislocations. In the case of growth on (11¯1)Si wafers, there is evidence of immediate strain relaxation taking place by numerous dislocations and also twinning. In the case of untwined film/substrate interfaces, Burgers circuits drawn around certain (amorphous-like) regions show a nonclosure with an edge-type a/4[1¯12] Burgers vector component visible in projection along [110]. Microtwins of multiples of half unit cells in thickness have been observed which occur at the growth interface between the Si(11¯1) buffer layer and the overlying Ge material. Models of the growth mechanisms to explain the interfacial configurations of each type of wafer are suggested. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  19. Synthesis of self-assembled Ge nano crystals employing reactive RF sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez H, A. [Universidad Autonoma del Estado de Hidalgo, Escuela Superior de Apan, Calle Ejido de Chimalpa Tlalayote s/n, Col. Chimalpa, Apan, Hidalgo (Mexico); Hernandez H, L. A. [IPN, Escuela Superior de Fisica y Matematicas, San Pedro Zacatenco, 07730 Ciudad de Mexico (Mexico); Monroy, B. M.; Santana R, G. [UNAM, Instituto de Investigaciones en Materiales, Apdo. Postal 70-360, 04510 Ciudad de Mexico (Mexico); Santoyo S, J.; Gallardo H, S. [IPN, Centro de Investigacion y de Estudios Avanzados, Departamento de Fisica, Apdo. Postal 14740, 07300 Ciudad de Mexico (Mexico); Marquez H, A. [Universidad de Guanajuato, Campus Irapuato-Salamanca, Departamento de Ingenieria Agricola, Km. 9 Carretera Irapuato-Silao, 36500 Irapuato, Guanajuato (Mexico); Mani G, P. G.; Melendez L, M. [Universidad Autonoma de Ciudad Juarez, Instituto de Ingenieria y Tecnologia, Departamento de Fisica y Matematicas, 32310 Ciudad Juarez, Chihuahua (Mexico)

    2016-11-01

    This work presents the results of a simple methodology able to control crystal size, dispersion and spatial distribution of germanium nano crystals (Ge-NCs). It takes advantage of a self-assembled process taken place during the deposit of the system SiO{sub 2}/Ge/SiO{sub 2} by reactive RF sputtering. Nanoparticles formation is controlled mainly by the roughness of the first SiO{sub 2} layer buy the ulterior interaction of the interlayer with the top layer also play a role. Structural quality of germanium nano crystals increases with roughness and the interlayer thickness. The tetragonal phase of germanium is produced and its crystallographic quality improves with interlayer thickness and oxygen partial pressure. Room temperature photoluminescence emission without a post growth thermal annealing process indicates that our methodology produces a low density of non-radiative traps. The surface topography of SiO{sub 2} reference samples was carried out by atomic force microscopy. The crystallographic properties of the samples were studied by grazing incidence X-ray diffraction at 1.5 degrees carried out in a Siemens D-5000 system employing the Cu Kα wavelength. (Author)

  20. Juvenile psittacine environmental enrichment.

    Science.gov (United States)

    Simone-Freilicher, Elisabeth; Rupley, Agnes E

    2015-05-01

    Environmental enrichment is of great import to the emotional, intellectual, and physical development of the juvenile psittacine and their success in the human home environment. Five major types of enrichment include social, occupational, physical, sensory, and nutritional. Occupational enrichment includes exercise and psychological enrichment. Physical enrichment includes the cage and accessories and the external home environment. Sensory enrichment may be visual, auditory, tactile, olfactory, or taste oriented. Nutritional enrichment includes variations in appearance, type, and frequency of diet, and treats, novelty, and foraging. Two phases of the preadult period deserve special enrichment considerations: the development of autonomy and puberty. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Experimental and ab initio study on structures and internal barriers to rotation in α-stannyl, germanium, and silicon carbamates

    Science.gov (United States)

    Jadidi, Khosrow; Khaligh, Nader Ghaffari; Islami, Parisa; Aryan, Reza; Arvin-Nezhad, Hamid

    2009-02-01

    A detailed study of structural parameters and internal rotational barriers in α-stannyl, germanium and silicon carbamates 1 [H 3 CX-CH 2-N(Me)CO 2Me X dbnd C, Si, Ge, Sn] were calculated at HF/6-311G, HF/3-21G and B3LYP/3-21G//HF/3-21G levels and compared with DNMR data of synthesized molecules and a literature X-ray data. Two minimum-energy conformers, namely A and B, with almost similar energies were found for these molecules. Effect of heteroatom on structure and relative energies ( Erel) between the participants in the conformational equilibrium (A ↔ B) of these carbamates has been investigated.

  2. Epitaxial growth of silicon and germanium on (100-oriented crystalline substrates by RF PECVD at 175 °C

    Directory of Open Access Journals (Sweden)

    Mauguin O.

    2012-11-01

    Full Text Available We report on the epitaxial growth of crystalline Si and Ge thin films by standard radio frequency plasma enhanced chemical vapor deposition at 175 °C on (100-oriented silicon substrates. We also demonstrate the epitaxial growth of silicon films on epitaxially grown germanium layers so that multilayer samples sustaining epitaxy could be produced. We used spectroscopic ellipsometry, Raman spectroscopy, transmission electron microscopy and X-ray diffraction to characterize the structure of the films (amorphous, crystalline. These techniques were found to provide consistent results and provided information on the crystallinity and constraints in such lattice-mismatched structures. These results open the way to multiple quantum-well structures, which have been so far limited to few techniques such as Molecular Beam Epitaxy or MetalOrganic Chemical Vapor Deposition.

  3. Modeling and Simulation of - and Silicon Germanium-Base Bipolar Transistors Operating at a Wide Range of Temperatures.

    Science.gov (United States)

    Shaheed, M. Reaz

    1995-01-01

    to provide consistently accurate values for base sheet resistance for both Si- and SiGe-base transistors over a wide range of temperatures. A model for plasma-induced bandgap narrowing suitable for implementation in a numerical simulator has been developed. The appropriate method of incorporating this model in a drift -diffusion solver is described. The importance of including this model for low temperature simulation is demonstrated. With these models in place, the enhanced simulator has been used for evaluating and designing the Si- and SiGe-base bipolar transistors. Silicon-germanium heterojunction bipolar transistors offer significant performance and cost advantages over conventional technologies in the production of integrated circuits for communications, computer and transportation applications. Their high frequency performance at low cost, will find widespread use in the currently exploding wireless communication market. However, the high performance SiGe-base transistors are prone to have a low common-emitter breakdown voltage. In this dissertation, a modification in the collector design is proposed for improving the breakdown voltage without sacrificing the high frequency performance. A comprehensive simulation study of p-n-p SiGe-base transistors has been performed. Different figures of merit such as drive current, current gain, cut -off frequency and Early voltage were compared between a graded germanium profile and an abrupt germanium profile. The differences in the performance level between the two profiles diminishes as the base width is scaled down.

  4. Measurement of pair production cross sections in Ge for the 1. 238-3. 548 MeV energy range

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, R K; Singh, K; Sahota, H S

    1985-02-28

    Pair production cross sections have been determined for the 1.238-3.548 MeV energy range in germanium (Z = 32) using a Ge(Li) gamma ray detector. The experimental results have been compared with the theoretical cross sections of previous workers. The results of the present measurements agree with the Bethe-Heitler results down to 1.771 MeV. However, at 1.238 MeV the experimental results are higher than all the theories.

  5. The electrical properties of a strongly disordered system based on lightly doped germanium compensated by disordered regions

    International Nuclear Information System (INIS)

    Evseev, V.A.; Konopleva, R.F.; Yuferev, A.A.

    1976-01-01

    A study was made of lightly doped (Nsub(Sb) approximately 10 15 cm -3 ) n-Ge, heavily compensated (K = Nsub(A)/N sub(D) approximately 1) by fast neutrons from a reactor. Irradiation is shown to produce, near n-p conversion (annealing has the same effect near p-n conversion), a random relief of electrostatic potential which is caused by the overlap of the space-charge regions surrounding disordered regions (DR). the random potential field results in a spatial 'bending' of the whole band spectrum of germanium, similar to the way it is observed in amorphous semiconductors because of their disorder. Experiments show the conduction in the DR overlap region to be of an activated nature, associated with the ejection of carriers to the corresponding 'percolation' levels. The activation energy of such conduction varies with the degree of compensation. The shift of the Fermi level depends on the degree of compensation here in a much more sensitive way than in the case of compensation by chemical impurities. The properties of Ge obtained by DR overlap and by compensation with chemical impurities are compared. A superlinear I-V characteristic producing the switching effect is observed in strong electric fields (E approximately 10 3 V cm -1 ). A suggestion is made that a study of disordered systems, based on lightly doped germanium which is compensated with DRs produced by high-energy particles, should both help to obtain new information on the parameters of the DRs proper and help to simulate the properties of the amorphous semiconductors. (author)

  6. Reduced-pressure chemical vapor deposition of boron-doped Si and Ge layers

    International Nuclear Information System (INIS)

    Bogumilowicz, Y.; Hartmann, J.M.

    2014-01-01

    We have studied the in-situ boron (B) doping of germanium (Ge) and silicon (Si) in Reduced Pressure-Chemical Vapor Deposition. Three growth temperatures have been investigated for the B-doping of Ge: 400, 600 and 750 °C at a constant growth pressure of 13300 Pa (i.e. 100 Torr). The B concentration in the Ge:B epilayer increases linearly with the diborane concentration in the gaseous phase. Single-crystalline Ge:B layers with B concentrations in-between 9 ∙ 10 17 and 1 ∙ 10 20 cm −3 were achieved. For the in-situ B doping of Si at 850 °C, two dichlorosilane mass flow ratios (MFR) have been assessed: F[SiH 2 Cl 2 ]/F[H 2 ] = 0.0025 and F[SiH 2 Cl 2 ]/F[H 2 ] = 0.0113 at a growth pressure of 2660 Pa (i.e. 20 Torr). Linear boron incorporation with the diborane concentration in the gas phase has been observed and doping levels in-between 3.5 ∙ 10 17 and 1 ∙ 10 20 cm −3 were achieved. We almost kept the same ratio of B versus Si atoms in the gas phase and in the Si epilayer. By contrast, roughly half of the B atoms present in the gas phase were incorporated in the Ge:B layers irrespective of the growth temperature. X-Ray Diffraction (XRD) allowed us to extract from the angular position of the Ge:B layer diffraction peak the substitutional B concentration. Values close to the B concentrations obtained by 4-probe resistivity measurements were obtained. Ge:B layers were smooth (< 1 m root mean square roughness associated with 20 × 20 μm 2 Atomic Force Microscopy images). Only for high F[B 2 H 6 ]/F[GeH 4 ] MFR (3.2 10 −3 ) did the Ge:B layers became rough; they were however still mono-crystalline (XRD). Above this MFR value, Ge:B layers became polycrystalline. - Highlights: • Boron doping of germanium and silicon in Reduced Pressure-Chemical Vapor Deposition • Linear boron incorporation in Ge:B and Si:B with the diborane flow • Single-crystal Ge:B layers with B concentrations in-between 9 ∙ 10 17 and 1 ∙ 10 20 cm −3 • Single-crystal Si

  7. Study of Ge loss during Ge condensation process

    International Nuclear Information System (INIS)

    Xue, Z.Y.; Di, Z.F.; Ye, L.; Mu, Z.Q.; Chen, D.; Wei, X.; Zhang, M.; Wang, X.

    2014-01-01

    Ge loss during Ge condensation process was investigated by transmission electron microscopy, Raman spectroscopy, secondary ion mass spectrometry and Rutherford backscattering spectrometry. This work reveals that Ge loss can be attributed to the Ge oxidation at SiO 2 /SiGe interface, Ge diffusion in SiO 2 layers and Ge trapped at buried SiO 2 /Si interface. During Ge condensation process, with the increase of the Ge content, the Si atoms become insufficient for selective oxidation at the oxide/SiGe interface. Consequently, the Si and Ge are oxidized simultaneously. When the Ge composition in SiGe layer increases further and approaches 100%, the Ge atoms begin to diffuse into the top SiO 2 layer and buried SiO 2 layer. However, the X-ray photoelectron spectrometry analysis manifests that the chemical states of the Ge in top SiO 2 layer are different from those in buried SiO 2 layer, as the Ge atoms diffused into top SiO 2 layer are oxidized to form GeO 2 in the subsequent oxidation step. With the increase of the diffusion time, a quantity of Ge atoms diffuse through buried SiO 2 layer and pile up at buried SiO 2 /Si interface due to the interfacial trapping. The SiO 2 /Si interface acts like a pump, absorbing Ge from a Ge layer continuously through a pipe-buried SiO 2 layer. With the progress of Ge condensation process, the quantity of Ge accumulated at SiO 2 /Si interface increases remarkably. - Highlights: • Ge loss during Ge condensation process is attributed to the Ge oxidation at SiO 2 /SiGe interface. • Ge diffusion in SiO 2 layers and Ge trapped at buried SiO 2 /Si interface • When Ge content in SiGe layer approaches 100%, Ge diffusion into the SiO 2 layer is observed. • Ge then gradually diffuses through buried SiO 2 layer and pile up at SiO 2 /Si interface

  8. Defect-impurity interactions in irradiated germanium

    International Nuclear Information System (INIS)

    Cleland, J.W.; James, F.J.; Westbrook, R.D.

    1975-07-01

    Results of experiments are used to formulate a better model for the structures of lattice defects and defect-impurity complexes in irradiated n-type Ge. Single crystals were grown by the Czochralski process from P, As, or Sb-doped melts, and less than or equal to 10 15 to greater than or equal to 10 17 oxygen cm -3 was added to the furnace chamber after approximately 1 / 3 of the crystal had been solidified. Hall coefficient and resistivity measurements (at 77 0 K) were used to determine the initial donor concentration due to the dopant and clustered oxygen, and infrared absorption measurements (at 11.7 μ) were used to determine the dissociated oxygen concentration. Certain impurity and defect-impurity interactions were then investigated that occurred as a consequence of selected annealing, quenching, Li diffusion, and irradiation experiments at approximately 300 0 K with 60 Co photons, 1.5 to 2.0 MeV electrons, or thermal energy neutrons. Particular attention was given to determining the electrical role of the irradiation produced interstitial and vacancy, and to look for any evidence from electrical and optical measurements of vacancy--oxygen, lithium--oxygen, and lithium--vacancy interactions. (U.S.)

  9. LArGe: active background suppression using argon scintillation for the GERDA 0νββ-experiment

    International Nuclear Information System (INIS)

    Agostini, M.; Budjas, D.; Schoenert, S.; Barnabe-Heider, M.; Cattadori, C.; Gangapshev, A.; Gusev, K.; Heisel, M.; Smolnikov, A.; Junker, M.; Klimenko, A.; Lubashevskiy, A.; Pelczar, K.; Zuzel, G.

    2015-01-01

    LArGe is a GERDA low-background test facility to study novel background suppression methods in a low-background environment, for future application in the GERDA experiment. Similar to GERDA, LArGe operates bare germanium detectors submersed into liquid argon (1 m 3 , 1.4tons), which in addition is instrumented with photomultipliers to detect argon scintillation light. The scintillation signals are used in anti-coincidence with the germanium detectors to effectively suppress background events that deposit energy in the liquid argon. The background suppression efficiency was studied in combination with a pulse shape discrimination (PSD) technique using a BEGe detector for various sources, which represent characteristic backgrounds to GERDA. Suppression factors of a few times 10 3 have been achieved. First background data of LArGe with a coaxial HPGe detector (without PSD) yield a background index of (0.12 - 4.6) x 10 -2 cts/(keV kg year) (90 % C.L.), which is at the level of GERDA Phase I. Furthermore, for the first time we monitor the natural 42 Ar abundance (parallel to GERDA), and have indication for the 2νββ-decay in natural germanium. These results show the effectivity of an active liquid argon veto in an ultra-low background environment. As a consequence, the implementation of a liquid argon veto in GERDA Phase II is pursued. (orig.)

  10. LArGe: active background suppression using argon scintillation for the Gerda 0ν β β -experiment

    Science.gov (United States)

    Agostini, M.; Barnabé-Heider, M.; Budjáš, D.; Cattadori, C.; Gangapshev, A.; Gusev, K.; Heisel, M.; Junker, M.; Klimenko, A.; Lubashevskiy, A.; Pelczar, K.; Schönert, S.; Smolnikov, A.; Zuzel, G.

    2015-10-01

    LArGe is a Gerda low-background test facility to study novel background suppression methods in a low-background environment, for future application in the Gerda experiment. Similar to Gerda, LArGe operates bare germanium detectors submersed into liquid argon (1 m^3, 1.4 tons), which in addition is instrumented with photomultipliers to detect argon scintillation light. The scintillation signals are used in anti-coincidence with the germanium detectors to effectively suppress background events that deposit energy in the liquid argon. The background suppression efficiency was studied in combination with a pulse shape discrimination (PSD) technique using a BEGe detector for various sources, which represent characteristic backgrounds to Gerda. Suppression factors of a few times 10^3 have been achieved. First background data of LArGe with a coaxial HPGe detector (without PSD) yield a background index of (0.12-4.6)× 10^{-2} cts/(keV kg year) (90 % C.L.), which is at the level of Gerda Phase I. Furthermore, for the first time we monitor the natural ^{42}Ar abundance (parallel to Gerda), and have indication for the 2ν β β -decay in natural germanium. These results show the effectivity of an active liquid argon veto in an ultra-low background environment. As a consequence, the implementation of a liquid argon veto in Gerda Phase II is pursued.

  11. LArGe: active background suppression using argon scintillation for the GERDA 0νββ-experiment

    Energy Technology Data Exchange (ETDEWEB)

    Agostini, M.; Budjas, D.; Schoenert, S. [Technische Universitaet Muenchen, Munich (Germany); Barnabe-Heider, M. [Technische Universitaet Muenchen, Munich (Germany); Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Cattadori, C. [Universita degli Studi di Milano, Milan (Italy); INFN, Milan (Italy); Gangapshev, A. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Institut for Nuclear Research, Moscow (Russian Federation); Gusev, K. [Technische Universitaet Muenchen, Munich (Germany); Joint Institut for Nuclear Research, Dubna (Russian Federation); National Research Center Kurchatov Institut, Moscow (Russian Federation); Heisel, M.; Smolnikov, A. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Junker, M. [Laboratori Nazionali del Gran Sasso, Assergi (Italy); Klimenko, A.; Lubashevskiy, A. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Joint Institut for Nuclear Research, Dubna (Russian Federation); Pelczar, K. [Jagellonian University, Cracow (Poland); Zuzel, G. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Jagellonian University, Cracow (Poland)

    2015-10-15

    LArGe is a GERDA low-background test facility to study novel background suppression methods in a low-background environment, for future application in the GERDA experiment. Similar to GERDA, LArGe operates bare germanium detectors submersed into liquid argon (1 m{sup 3}, 1.4tons), which in addition is instrumented with photomultipliers to detect argon scintillation light. The scintillation signals are used in anti-coincidence with the germanium detectors to effectively suppress background events that deposit energy in the liquid argon. The background suppression efficiency was studied in combination with a pulse shape discrimination (PSD) technique using a BEGe detector for various sources, which represent characteristic backgrounds to GERDA. Suppression factors of a few times 10{sup 3} have been achieved. First background data of LArGe with a coaxial HPGe detector (without PSD) yield a background index of (0.12 - 4.6) x 10{sup -2} cts/(keV kg year) (90 % C.L.), which is at the level of GERDA Phase I. Furthermore, for the first time we monitor the natural {sup 42}Ar abundance (parallel to GERDA), and have indication for the 2νββ-decay in natural germanium. These results show the effectivity of an active liquid argon veto in an ultra-low background environment. As a consequence, the implementation of a liquid argon veto in GERDA Phase II is pursued. (orig.)

  12. Distribution and Substitution Mechanism of Ge in a Ge-(Fe-Bearing Sphalerite

    Directory of Open Access Journals (Sweden)

    Nigel J. Cook

    2015-03-01

    Full Text Available The distribution and substitution mechanism of Ge in the Ge-rich sphalerite from the Tres Marias Zn deposit, Mexico, was studied using a combination of techniques at μm- to atomic scales. Trace element mapping by Laser Ablation Inductively Coupled Mass Spectrometry shows that Ge is enriched in the same bands as Fe, and that Ge-rich sphalerite also contains measurable levels of several other minor elements, including As, Pb and Tl. Micron- to nanoscale heterogeneity in the sample, both textural and compositional, is revealed by investigation using Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM combined with Synchrotron X-ray Fluorescence mapping and High-Resolution Transmission Electron Microscopy imaging of FIB-prepared samples. Results show that Ge is preferentially incorporated within Fe-rich sphalerite with textural complexity finer than that of the microbeam used for the X-ray Absorption Near Edge Structure (XANES measurements. Such heterogeneity, expressed as intergrowths between 3C sphalerite and 2H wurtzite on  zones, could be the result of either a primary growth process, or alternatively, polystage crystallization, in which early Fe-Ge-rich sphalerite is partially replaced by Fe-Ge-poor wurtzite. FIB-SEM imaging shows evidence for replacement supporting the latter. Transformation of sphalerite into wurtzite is promoted by (111* twinning or lattice-scale defects, leading to a heterogeneous ZnS sample, in which the dominant component, sphalerite, can host up to ~20% wurtzite. Ge K-edge XANES spectra for this sphalerite are identical to those of the germanite and argyrodite standards and the synthetic chalcogenide glasses GeS2 and GeSe2, indicating the Ge formally exists in the tetravalent form in this sphalerite. Fe K-edge XANES spectra for the same sample indicate that Fe is present mainly as Fe2+, and Cu K-edge XANES spectra are characteristic for Cu+. Since there is no evidence for coupled substitution involving a monovalent

  13. The Effect of Alumina and Magnesia Supported Germanium Nanoparticles on the Growth of Carbon Nanotubes in the Chemical Vapor Deposition Method

    Directory of Open Access Journals (Sweden)

    Ghazaleh Allaedini

    2015-01-01

    Full Text Available The effect of alumina and magnesia supported germanium (Ge nanoparticles on the synthesis of carbon nanotubes (CNTs using the chemical vapor deposition (CVD method in atmospheric pressure was investigated. The TEM micrographs confirmed the formation of carbon nanotubes, and the field emission scanning electron microscopy (FESEM analysis suggested a tip-growth mechanism for the grown carbon nanotubes. The X-ray diffraction (XRD pattern indicated a graphitic nature of the carbon nanotubes. The obtained CNTs using Ge nanoparticles supported by MgO resulted in a higher degree of graphitization than the CNTs obtained using Ge nanoparticles supported by Al2O3. Raman spectroscopy analysis of the CNTs confirmed the presence of radial breathing modes (RBM, which verified the formation of CNTs. High frequency Raman analysis demonstrated that the degree of graphitization of the synthesized CNTs using magnesia supported Ge nanoparticles is higher than that of the alumina supported Ge nanoparticles with the values of (ID/IG ratios equal to 0.45 and 0.73, respectively.

  14. A study of the optical properties and adhesion of zinc sulfide anti-reflection thin film coated on a germanium substrate

    Energy Technology Data Exchange (ETDEWEB)

    Firoozifar, S.A.R. [Atomic and Molecular Group, Faculty of Physics, Yazd University, Yazd (Iran, Islamic Republic of); Behjat, A., E-mail: abehjat@yazduni.ac.ir [Atomic and Molecular Group, Faculty of Physics, Yazd University, Yazd (Iran, Islamic Republic of); Photonics Research Group, Engineering Research Center, Yazd University, Yazd (Iran, Islamic Republic of); Kadivar, E. [Physics Department, Persian Gulf University, Bushehr (Iran, Islamic Republic of); Ghorashi, S.M.B.; Zarandi, M. Borhani [Atomic and Molecular Group, Faculty of Physics, Yazd University, Yazd (Iran, Islamic Republic of)

    2011-11-01

    To conduct this study, zinc sulfide (ZnS) thin films deposited on germanium (Ge) substrates were prepared by an evaporation method. The effects of deposition rate and annealing on the optical properties and adhesion of the ZnS thin films were investigated. The transmission intensity and the X-ray diffraction (XRD) pattern of the samples showed that the transmittance of the samples decreases by increasing the evaporation rates. However, with the increase of the annealing temperature, crystallinity of the thin films improves which, in turn, results in the enhancement of the transmission intensity in a far infrared region. The maximum grain size was obtained at the annealing temperature of 225 deg. C. Our experimental results also show that evaporation rate and annealing influences the adhesion of ZnS thin films to Ge substrates.

  15. Other enrichment related contracts

    International Nuclear Information System (INIS)

    Hall, J.C.

    1978-01-01

    In addition to long-term enrichment contracts, DOE has other types of contracts: (1) short-term, fixed-commitment enrichment contract; (2) emergency sales agreement for enriched uranium; (3) feed material lease agreement; (4) enriched uranium storage agreement; and (5) feed material usage agreement