Dry cleaning of fluorocarbon residues by low-power electron cyclotron resonance hydrogen plasma

CERN Document Server

Lim, S H; Yuh, H K; Yoon Eui Joon; Lee, S I

1988-01-01

A low-power ( 50 W) electron cyclotron resonance hydrogen plasma cleaning process was demonstrated for the removal of fluorocarbon residue layers formed by reactive ion etching of silicon dioxide. The absence of residue layers was confirmed by in-situ reflection high energy electron diffraction and cross-sectional high resolution transmission electron microscopy. The ECR hydrogen plasma cleaning was applied to contact cleaning of a contact string structure, resulting in comparable contact resistance arising during by a conventional contact cleaning procedure. Ion-assisted chemical reaction involving reactive atomic hydrogen species generated in the plasma is attributed for the removal of fluorocarbon residue layers.

Analysis of the X-ray emission spectra of copper, germanium and rubidium plasmas produced at the Phelix laser facility

Science.gov (United States)

Comet, M.; Pain, J.-C.; Gilleron, F.; Piron, R.; Denis-Petit, D.; Méot, V.; Gosselin, G.; Morel, P.; Hannachi, F.; Gobet, F.; Tarisien, M.; Versteegen, M.

2017-03-01

We present the analysis of X-ray emission spectra of copper, germanium and rubidium plasmas measured at the Phelix laser facility. The laser intensity was around 6×1014 W.cm-2. The analysis is based on the hypothesis of an homogeneous plasma in local thermodynamic equilibrium using an effective temperature. This temperature is deduced from hydrodynamic simulations and collisional-radiative computations. Spectra are then calculated using the LTE opacity codes OPAMCDF and SCO-RCG and compared to experimental data.

Plasma cleaning and analysis of archeological artefacts from Sipan

Energy Technology Data Exchange (ETDEWEB)

Saettone, E A O [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, CEP 05508-900 (Brazil); Matta, J A S da [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, CEP 05508-900 (Brazil); Alva, W [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, CEP 05508-900 (Brazil); Chubaci, J F O [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, CEP 05508-900 (Brazil); Fantini, M C A [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, CEP 05508-900 (Brazil); Galvao, R M O [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, CEP 05508-900 (Brazil); Kiyohara, P [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, CEP 05508-900 (Brazil); Tabacniks, M H [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, CEP 05508-900 (Brazil)

2003-04-07

A novel procedure using plasma sputtering in an electron-cyclotron-resonance device has been applied to clean archeological MOCHE artefacts, unearthed at the Royal Tombs of Sipan. After successful cleaning, the pieces were analysed by a variety of complementary techniques, namely proton-induced x-ray emission, Rutherford backscattering spectroscopy, x-ray diffraction, electron microscopy, and inductively coupled plasma mass spectroscopy. With these techniques, it has been possible to not only determine the profiles of the gold and silver surface layers, but also to detect elements that may be relevant to explain the gilding techniques skillfully developed by the metal smiths of the MOCHE culture.

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.

Post-CMP cleaning for metallic contaminant removal by using a remote plasma and UV/ozone

International Nuclear Information System (INIS)

Lim, Jong Min; Jeon, Bu Yong; Lee, Chong Mu

2000-01-01

For the chemical mechanical polishing (CMP) process to be successful, it is important to establish a good post-CMP cleaning process that will remove not only slurry and particles but also metallic impurities from the polished surface. The common metallic contaminants found after oxide CMP and Cu CMP include Cu, K, and Fe. Scrubbing, a popular method for post-CMP cleaning, is effective in removing particles, but removal of metallic contaminants using this method is not so effective. In this study, the removal of Fe metallic contaminants like Fe, which are commonly found on the wafer surface after CMP processes, was investigated using remote-hydrogen-plasma and UV/O 3 cleaning techniques. Our results show that metal contaminants, including Fe, can be effectively removed by using a hydrogen-plasma or UV/O 3 cleaning technique performed under optimal process conditions. In remote plasma H 2 cleaning, contaminant removal is enhanced with decreasing plasma exposure time and increasing rf-power. The optimal process condition for the removal of the Fe impurities existing on the wafer surface is an rf-power of 100 W. Plasma cleaning for 5 min or less is effective in removing Fe contaminants, but a plasma exposure time of 1 min is more appropriate than 5 min in view of the process time, The surface roughness decreased by 30∼50 % after remote-H 2 -plasma cleaning. On the other hand, the highest efficiency of Fe-impurity removal was achieved for an UV exposure time of 30 s. The removal mechanism for the Fe contaminants in the remote-H 2 -plasma and the UV/O 3 cleaning processes is considered to be the liftoff of Fe atoms when the SiO is removed by evaporation after the chemical or native SiO 2 formed underneath the metal atoms reacts with H + and e - to form SiO

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.)

Plasma cleaning of ITER edge Thomson scattering mock-up mirror in the EAST tokamak

Science.gov (United States)

Yan, Rong; Moser, Lucas; Wang, Baoguo; Peng, Jiao; Vorpahl, Christian; Leipold, Frank; Reichle, Roger; Ding, Rui; Chen, Junling; Mu, Lei; Steiner, Roland; Meyer, Ernst; Zhao, Mingzhong; Wu, Jinhua; Marot, Laurent

2018-02-01

First mirrors are the key element of all optical and laser diagnostics in ITER. Facing the plasma directly, the surface of the first mirrors could be sputtered by energetic particles or deposited with contaminants eroded from the first wall (tungsten and beryllium), which would result in the degradation of the reflectivity. The impurity deposits emphasize the necessity of the first mirror in situ cleaning for ITER. The mock-up first mirror system for ITER edge Thomson scattering diagnostics has been cleaned in EAST for the first time in a tokamak using radio frequency capacitively coupled plasma. The cleaning properties, namely the removal of contaminants and homogeneity of cleaning were investigated with molybdenum mirror insets (25 mm diameter) located at five positions over the mock-up plate (center to edge) on which 10 nm of aluminum oxide, used as beryllium proxy, were deposited. The cleaning efficiency was evaluated using energy dispersive x-ray spectroscopy, reflectivity measurements and x-ray photoelectron spectroscopy. Using argon or neon plasma without magnetic field in the laboratory and with a 1.7 T magnetic field in the EAST tokamak, the aluminum oxide films were homogeneously removed. The full recovery of the mirrors’ reflectivity was attained after cleaning in EAST with the magnetic field, and the cleaning efficiency was about 40 times higher than that without the magnetic field. All these results are promising for the plasma cleaning baseline scenario of ITER.

Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

International Nuclear Information System (INIS)

Hicks, Robert F.; Herrmann, Hans W.

2003-01-01

The objective of this work is to demonstrate a practical, atmospheric pressure plasma tool for the surface decontamination of radioactive waste. Decontamination of radioactive materials that have accumulated on the surfaces of equipment and structures is a challenging and costly undertaking for the US Department of Energy. Our technology shows great potential for accelerating this clean up effort

Discharge cleaning on KSTAR 1st plasma events

Energy Technology Data Exchange (ETDEWEB)

Kwak, J. G.; Wang, J. S. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, J. S.; Yang, H. L.; Kim, K. P.; Kim, K. M. [National Fusion Research Institute, Daejeon (Korea, Republic of)

2008-10-15

A discharge cleaning of a vacuum vessel was conducted with a GDC (Glow discharge cleaning) and a ICRF-DC(ICRF assisted discharge cleaning) for the KSTAR first plasma event period. The base pressure of the vessel was kept below 10-7 mbar via a cool down of the cryo-vessel, a 100C baking, and a GDC. (Partial pressure of hydrogen and nitrogen is below 10-8 mbar). The diagnostics for a discharge cleaning is a differential pumped RGA attached to a pumping duct and a cold cathode and a hot cathode gauge attached to the vessel and the pumping duct respectively. To analyze the discharge characteristics, a microwave interferometer, Bremsstahlung, H-alphas and a TV camera were used. Two straps among the four straps of the ICRF antenna are used for the ICRF-DC and ICRF heating experiments. The phase difference between the adjacent straps was 0 degree and the operating frequency was 30-33MHz.

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

Plasma cleaning and analysis of archeological artefacts from Sipán

Science.gov (United States)

Saettone, E. A. O.; da Matta, J. A. S.; Alva, W.; Chubaci, J. F. O.; Fantini, M. C. A.; Galvão, R. M. O.; Kiyohara, P.; Tabacniks, M. H.

2003-04-01

A novel procedure using plasma sputtering in an electron-cyclotron-resonance device has been applied to clean archeological MOCHE artefacts, unearthed at the Royal Tombs of Sipán. After successful cleaning, the pieces were analysed by a variety of complementary techniques, namely proton-induced x-ray emission, Rutherford backscattering spectroscopy, x-ray diffraction, electron microscopy, and inductively coupled plasma mass spectroscopy. With these techniques, it has been possible to not only determine the profiles of the gold and silver surface layers, but also to detect elements that may be relevant to explain the gilding techniques skillfully developed by the metal smiths of the MOCHE culture.

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

Effects of plasma cleaning of the Cu seed layer surface on Cu electroplating

International Nuclear Information System (INIS)

O, Jun Hwan; Lee, Seong Wook; Kim, Jae Bum; Lee, Chong Mu

2001-01-01

Effects of plasma pretreatment to Cu seed/tantalum nitride (TaN)/ borophosphosilicate glass (BPSG) samples on copper (Cu) electroplating were investigated. Copper seed layers were deposited by magnetron sputtering onto tantalum nitride barrier layers before electroplating copper in the forward pulsed mode. The Cu seed layer was cleaned by plasma H 2 and N 2 prior to electroplating a copper film. Cu films electroplated on the copper seed layer with plasma pretreatment showed better electrical and physical properties such as electrical resistivities, surface morphologies, levels of impurities, adhesion and surface roughness than those without plasma pretreatment. It is shown that carbon and metal oxide contaminants at the sputtered Cu seed/TaN surface could be effectively removed by plasma H 2 cleaning. The degree of the (111) prefered orientation of the Cu film with plasma H 2 pretreatment is as high as pulse plated Cu film without plasma pretreatment. Also, plasma H 2 precleaning is more effective in enhancing the Cu electroplating properties onto the Cu seed layer than plasma N 2 precleaning

Method for Cleaning Laser-Drilled Holes on Printed Wiring Boards by Plasma Treatment

Science.gov (United States)

Hirogaki, Toshiki; Aoyama, Eiichi; Minagi, Ryu; Ogawa, Keiji; Katayama, Tsutao; Matsuoka, Takashi; Inoue, Hisahiro

We propose a new method for cleaning blind via holes after laser drilling of PWBs using oxygen plasma treatment. This report dealt with three kinds of PWB materials: epoxy resin and two kinds of aramid fiber reinforced plastics (AFRP: Technora or Kevlar fiber reinforcement). We observed the drilled holes after plasma treatment using both an optical and a scanning electric microscope (SEM). It was confirmed that adequate etching took place in the drilled holes by plasma treatment. We also compared the hole wall and hole bottom after plasma treatment with ones after chemical etching. It was clear that there was no damage to the aramid fiber tip on the hole wall, and that a smooth roughness of the hole wall was obtained by means of plasma treatment. As a result, we demonstrated that the plasma treatment is effective in cleaning the laser drilled holes of PWBs.

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.

Thermal recrystallization of physical vapor deposition based germanium thin films on bulk silicon (100)

KAUST Repository

Hussain, Aftab M.

2013-08-16

We demonstrate a simple, low-cost, and scalable process for obtaining uniform, smooth surfaced, high quality mono-crystalline germanium (100) thin films on silicon (100). The germanium thin films were deposited on a silicon substrate using plasma-assisted sputtering based physical vapor deposition. They were crystallized by annealing at various temperatures ranging from 700 °C to 1100 °C. We report that the best quality germanium thin films are obtained above the melting point of germanium (937 °C), thus offering a method for in-situ Czochralski process. We show well-behaved high-κ /metal gate metal-oxide-semiconductor capacitors (MOSCAPs) using this film. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Protecting integrated circuits from excessive charge accumulation during plasma cleaning of multichip modules

Science.gov (United States)

Rodenbeck, Christopher T; Girardi, Michael

2015-04-21

Internal nodes of a constituent integrated circuit (IC) package of a multichip module (MCM) are protected from excessive charge during plasma cleaning of the MCM. The protected nodes are coupled to an internal common node of the IC package by respectively associated discharge paths. The common node is connected to a bond pad of the IC package. During MCM assembly, and before plasma cleaning, this bond pad receives a wire bond to a ground bond pad on the MCM substrate.

Unexpected properties of the inductively coupled plasma induced defect in germanium

Energy Technology Data Exchange (ETDEWEB)

Coelho, S.M.M., E-mail: sergio@up.ac.za; Auret, F.D.; Janse van Rensburg, P.J.; Nel, J.M.

2014-04-15

Inductively coupled plasma (ICP) etching of germanium introduces a single defect, the E{sub 0.31} electron trap, for a large range of argon partial pressures from 4×10{sup –3} to 6.5×10{sup –4} mbar that correspond to ion energies of 8 to 60 eV. Ge of three crystallographic orientations, (1 0 0), (1 1 0) and (1 1 1), treated with 20 and 60 eV ICP had defect concentration profiles that were similar in appearance, with a maximum concentration of 10{sup 14} cm{sup −3} extending more than a µm into the material, approximately three orders of magnitude deeper than what TRIM simulations predicted. All profiles were measured using Laplace deep level transient spectroscopy (L-DLTS), a technique that is sensitive to defect concentrations as low as 10{sup 11} cm{sup −3}. Isochronal annealing of samples showed concentration curves broadening after a 400 K anneal and decreasing to the 10{sup 13} cm{sup −3} level after a 450 K anneal. Unannealed samples measured after a year exhibited similar decreases in defect concentration without broadening of their profiles. A 550 K anneal lowered the defect concentration to levels below the L-DLTS detection limit. Thereafter additional plasma treatment of the surface failed to reintroduce this defect indicating that the structure required for the formation of E{sub 0.31} was no longer present in the region under observation.

Si-compatible cleaning process for graphene using low-density inductively coupled plasma.

Science.gov (United States)

Lim, Yeong-Dae; Lee, Dae-Yeong; Shen, Tian-Zi; Ra, Chang-Ho; Choi, Jae-Young; Yoo, Won Jong

2012-05-22

We report a novel cleaning technique for few-layer graphene (FLG) by using inductively coupled plasma (ICP) of Ar with an extremely low plasma density of 3.5 × 10(8) cm(-3). It is known that conventional capacitively coupled plasma (CCP) treatments destroy the planar symmetry of FLG, giving rise to the generation of defects. However, ICP treatment with extremely low plasma density is able to remove polymer resist residues from FLG within 3 min at a room temperature of 300 K while retaining the carbon sp(2)-bonding of FLG. It is found that the carrier mobility and charge neutrality point of FLG are restored to their pristine defect-free state after the ICP treatment. Considering the application of graphene to silicon-based electronic devices, such a cleaning method can replace thermal vacuum annealing, electrical current annealing, and wet-chemical treatment due to its advantages of being a low-temperature, large-area, high-throughput, and Si-compatible process.

Design of a tritium decontamination workstation based on plasma cleaning

International Nuclear Information System (INIS)

Antoniazzi, A.B.; Shmayda, W.T.; Fishbien, B.F.

1993-01-01

A design for a tritium decontamination workstation based on plasma cleaning is presented. The activity of tritiated surfaces are significantly reduced through plasma-surface interactions within the workstation. Such a workstation in a tritium environment can routinely be used to decontaminate tritiated tools and components. The main advantage of such a station is the lack of low level tritiated liquid waste. Gaseous tritiated species are the waste products with can with present technology be separated and contained

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.

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.

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.

Fabrication of diamond-coated germanium ATR prisms for IR-spectroscopy

Czech Academy of Sciences Publication Activity Database

Babchenko, Oleg; Kozak, Halyna; Ižák, Tibor; Stuchlík, Jiří; Remeš, Zdeněk; Rezek, Bohuslav; Kromka, Alexander

2016-01-01

Roč. 87, May (2016), 67-73 ISSN 0924-2031 R&D Projects: GA ČR GA15-01687S Institutional support: RVO:68378271 Keywords : diamond * low temperature growth * linear antenna microwave plasma * germanium * SEM * FTIR Subject RIV: JI - Composite Materials Impact factor: 1.740, year: 2016

ECR plasma cleaning for superconducting cavities

Energy Technology Data Exchange (ETDEWEB)

Takeuchi, Suehiro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2000-02-01

A superconducting linac has been operating well as a heavy ion energy booster of the tandem accelerator at JAERI since 1994. Forty superconducting quarter wave resonators are used in the linac. They have high performances in average. Some of them are, however, suffering from 'Q-disease' that has been caused by hydrogen absorption into niobium during electro-polishing and the precipitation of niobium-hydrides on the surface at the vicinity of about 120K during precooling. A method of electron cyclotron resonance (ECR) plasma cleaning was applied to spare resonator in order to investigate if it is useful as a curing method of Q-disease. ECR plasma was excited in the resonator by 2.45 GHz microwave in a magnetic field of about 87.5 mT. In the first preliminary experiments, hydrogen, helium, water and oxigen gases were investigated. Every case was done at a pressure of about 3x10{sup -3} Pa. The results show that apparent recovery from Q-disease was found with helium and oxigen gases. (author)

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.

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.

Cleaning of niobium surface by plasma of diffuse discharge at atmospheric pressure

Science.gov (United States)

Tarasenko, V. F.; Erofeev, M. V.; Shulepov, M. A.; Ripenko, V. S.

2017-07-01

Elements composition of niobium surface before and after plasma treatment by runaway electron preionized diffuse discharge was investigated in atmospheric pressure nitrogen flow by means of an Auger electron spectroscopy. Surface characterizations obtained from Auger spectra show that plasma treatment by diffuse discharge after exposure of 120000 pulses provides ultrafine surface cleaning from carbon contamination. Moreover, the surface free energy of the treated specimens increased up to 3 times, that improve its adhesion property.

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.

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.

A variable temperature cryostat that produces in situ clean-up germanium detector surfaces

International Nuclear Information System (INIS)

Pehl, R.H.; Madden, N.W.; Malone, D.F.; Cork, C.P.; Landis, D.A.; Xing, J.S.; Friesel, D.L.

1988-11-01

Variable temperature cryostats that can maintain germanium detectors at temperatures from 82 K to about 400 K while the thermal shield surrounding the detectors remains much colder when the detectors are warmed have been developed. Cryostats such as these offer the possibility of cryopumping material from the surface of detectors to the colder thermal shield. The diode characteristics of several detectors have shown very significant improvement following thermal cycles up to about 150 K in these cryostats. Important applications for cryostats having this attribute are many. 4 figs

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

Plasma cleaning and the removal of carbon from metal surfaces

International Nuclear Information System (INIS)

Baker, M.A.

1980-01-01

In an investigation of the plasma cleaning of metals and the plasma etching of carbon, a mass spectrometer was used as a sensitive process monitor. CO 2 produced by the plasma oxidation of carbon films or of organic contamination and occluded carbon at the surfaces of metals proved to be the most suitable gas to monitor. A good correlation was obtained between the measured etch rate of carbon and the resulting CO 2 partial pressure monitored continuously with the mass spectrometer. The rate of etching of carbon in an oxygen-argon plasma at 0.1 Torr was high when the carbon was at cathode potential and low when it was electrically isolated in the plasma, thus confirming the findings of previous workers and indicating the importance of ion bombardment in the etching process. Superficial organic contamination on the surfaces of the metals aluminium and copper and of the alloy Inconel 625 was quickly removed by the oxygen-argon plasma when the metal was electrically isolated and also when it was at cathode potential. Occluded carbon (or carbides) at or near the surfaces of the metals was removed slowly and only when the metal was at cathode potential, thus illustrating again the importance of ion bombardment. (Auth.)

Mapping the electromagnetic field confinement in the gap of germanium nanoantennas with plasma wavelength of 4.5 micrometers

NARCIS (Netherlands)

Calandrini, Eugenio; Venanzi, Tommaso; Appugliese, Felice; Badioli, Michela; Giliberti, Valeria; Baldassarre, Leonetta; Biagioni, Paolo; De Angelis, Francesco; Klesse, Wolfgang M.; Scappucci, G.; Ortolani, Michele

2016-01-01

We study plasmonic nanoantennas for molecular sensing in the mid-infrared made of heavily doped germanium, epitaxially grown with a bottom-up doping process and featuring free carrier density in excess of 10²⁰ cm^-3. The dielectric function of the 250 nm thick germanium film

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)

Experimental Study on Indoor Air Cleaning Technique of Nano-Titania Catalysis Under Plasma Discharge

International Nuclear Information System (INIS)

Gao Deli; Yang Xuechang; Zhou Fei; Wu Yuhuang

2008-01-01

In this study, a new technique of air cleaning by plasma combined with catalyst was proposed, which consisted of electrostatic precipitation, volatile organic compounds (VOCs) decomposition and sterilization. A novel indoor air purifier based on this technique was adopted. The experimental results showed that formaldehyde decomposition by the plasma-catalyst hybrid system was more efficient than that by plasma only. Positive discharge was better than negative discharge in formaldehyde removal. Meanwhile, the outlet concentration of ozone byproduct was effectively reduced by the nano-titania catalyst.

Characterization of Carbon-Contaminated B4C-Coated Optics after Chemically Selective Cleaning with Low-Pressure RF Plasma.

Science.gov (United States)

Moreno Fernández, H; Rogler, D; Sauthier, G; Thomasset, M; Dietsch, R; Carlino, V; Pellegrin, E

2018-01-22

Boron carbide (B 4 C) is one of the few materials that is expected to be most resilient with respect to the extremely high brilliance of the photon beam generated by free electron lasers (FELs) and is thus of considerable interest for optical applications in this field. However, as in the case of many other optics operated at light source facilities, B 4 C-coated optics are subject to ubiquitous carbon contaminations. Carbon contaminations represent a serious issue for the operation of FEL beamlines due to severe reduction of photon flux, beam coherence, creation of destructive interference, and scattering losses. A variety of B 4 C cleaning technologies were developed at different laboratories with varying success. We present a study regarding the low-pressure RF plasma cleaning of carbon contaminated B 4 C test samples via inductively coupled O 2 /Ar, H 2 /Ar, and pure O 2 RF plasma produced following previous studies using the same ibss GV10x downstream plasma source. Results regarding the chemistry, morphology as well as other aspects of the B 4 C optical coating before and after the plasma cleaning are reported. We conclude that among the above plasma processes only plasma based on pure O 2 feedstock gas exhibits the required chemical selectivity for maintaining the integrity of the B 4 C optical coatings.

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.

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.

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

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

No positive effect of Acid etching or plasma cleaning on osseointegration of titanium implants in a canine femoral condyle press-fit model

DEFF Research Database (Denmark)

Saksø, Henrik; Jakobsen, Thomas Vestergaard; Mortensen, Mikkel Saksø

2013-01-01

Implant surface treatments that improve early osseointegration may prove useful in long-term survival of uncemented implants. We investigated Acid Etching and Plasma Cleaning on titanium implants.......Implant surface treatments that improve early osseointegration may prove useful in long-term survival of uncemented implants. We investigated Acid Etching and Plasma Cleaning on titanium implants....

RF plasma cleaning of silicon substrates with high-density polyethylene contamination

Science.gov (United States)

Cagomoc, Charisse Marie D.; De Leon, Mark Jeffry D.; Ebuen, Anna Sophia M.; Gilos, Marlo Nicole R.; Vasquez, Magdaleno R., Jr.

2018-01-01

Upon contact with a polymeric material, microparticles from the polymer may adhere to a silicon (Si) substrate during device processing. The adhesion contaminates the surface and, in turn, leads to defects in the fabricated Si-based microelectronic devices. In this study, Si substrates with artificially induced high-density polyethylene (HDPE) contamination was exposed to 13.56 MHz radio frequency (RF) plasma utilizing argon and oxygen gas admixtures at a power density of 5.6 W/cm2 and a working pressure of 110 Pa for up to 6 min of treatment. Optical microscopy studies revealed the removal of up to 74% of the polymer contamination upon plasma exposure. Surface free energy (SFE) increased owing to the removal of contaminants as well as the formation of polar groups on the Si surface after plasma treatment. Atomic force microscopy scans showed a decrease in surface roughness from 12.25 nm for contaminated samples to 0.77 nm after plasma cleaning. The smoothening effect can be attributed to the removal of HDPE particles from the surface. In addition, scanning electron microscope images showed that there was a decrease in the amount of HDPE contaminants adhering onto the surface after plasma exposure.

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

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.

Influence of an External DC Electric Current on Plasma Cleaning Rate: an Application on the Enlarged Plasma-Surface Theory

International Nuclear Information System (INIS)

Xaplanteris, Constantine L.; Filippaki, Eleni D.

2013-01-01

During the last decades many researchers have been occupied with other plasma applications apart from the big challenge which the thermonuclear fusion poses. Many experiments have been carried out on the plasma behavior in contact with a solid surface; when the surface material consists of chemical compounds (e.g. oxides of metals), then the plasma chemistry takes place. The present paper contains the final experimental and theoretical work of Plasma Laboratory at “Demokritos , which consists of an elaboration of plasma sheath parameters adapted to experimental conditions, a suitable choice of plasma gases (either H 2 or N 2 ), and an electric potential current enforcement on objects. Additionally, a brief theory is given to explain the results, with a short reference to both boundary phenomena in thermonuclear reactors and low pressure plasma of glow discharges, so as to reveal the similarities and differences of these two cases. An extensive examination of the treated objects by X-ray diffraction method (XRD) gives results in agreement with the theoretical predictions. Using this improvement on plasma restoration system, (a combination of electric current on metallic object into suitable plasma), it is shown that better results can be achieved on the cleaning and conservation of archaeological objects. (plasma technology)

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.

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.

Amorphous Silicon-Germanium Films with Embedded Nanocrystals for Thermal Detectors with Very High Sensitivity

Directory of Open Access Journals (Sweden)

Cesar Calleja

2016-01-01

Full Text Available We have optimized the deposition conditions of amorphous silicon-germanium films with embedded nanocrystals in a plasma enhanced chemical vapor deposition (PECVD reactor, working at a standard frequency of 13.56 MHz. The objective was to produce films with very large Temperature Coefficient of Resistance (TCR, which is a signature of the sensitivity in thermal detectors (microbolometers. Morphological, electrical, and optical characterization were performed in the films, and we found optimal conditions for obtaining films with very high values of thermal coefficient of resistance (TCR = 7.9% K−1. Our results show that amorphous silicon-germanium films with embedded nanocrystals can be used as thermosensitive films in high performance infrared focal plane arrays (IRFPAs used in commercial thermal cameras.

Discharge cleaning of carbon deposits

International Nuclear Information System (INIS)

Mozetic, M.; Vesel, A.; Drenik, A.

2006-01-01

Experimental results of discharge cleaning of carbon deposits are presented. Deposits were prepared by creating plasma in pure methane. The methane was cracked in RF discharge at the output power of 250 W. The resultant radicals were bonded to the wall of discharge vessel forming a thin film of hydrogenated black carbon with the thickness of about 200nm. The film was then cleaned in situ by oxygen plasma with the density of about 1x10 16 m -3 , electron temperature of 5 eV, neutral gas kinetic temperature of about 100 0 C and neutral atom density of 6x10 21 m -3 . The treatment time was 30 minutes. The efficiency of plasma cleaning was monitored by optical emission spectroscopy. As long as the wall was contaminated with carbon deposit, substantial emission of the CO molecules was detected. As the cleaning was in progress, the CO emission was decreasing and vanished after 30 minutes when the discharge vessel became free of any carbon. The results are explained by interaction of plasma radicals with carbon deposits. (author)

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)

Application to cleaning of waste plastic surfaces using atmospheric non-thermal plasma jets

Energy Technology Data Exchange (ETDEWEB)

Araya, Masayuki [Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan); Yuji, Toshifumi [Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8550 (Japan)]. E-mail: t-yuji@hiroshima-cmt.ac.jp; Watanabe, Takayuki [Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan); Kashihara, Junzou [SHARP corporation, 1-9-2 Nakase, Mihama-Ku, Chiba 261-8520 (Japan); Sumida, Yoshitake [SHARP corporation, 2613-1 Ichinomoto-cho, Tenri 632-8567 (Japan)

2007-03-12

The removal of paint on the surface of waste plastics is difficult by the conventional process; in this research, a new cleaning mechanism using atmospheric plasmas was examined through optical emission spectroscopy, electron spectroscopy for chemical analysis, and scanning electron microscopy. Results indicate that an increase of pulse frequency enables for a short processing time for the removal of the paint film, signifying that the production of radicals in plasma, especially oxygen radicals, can be controlled by pulse frequency. Plasma jets were generated under the experimental conditions of an input power of 250 W to 400 W, a pulse frequency of 2 kHz to 12 kHz, and a plasma gas flow rate of 30 L/min. Examination of the intensity ratio of the reactive species, as measured by emission spectroscopy, showed that the O/N value increased with an increase in pulse frequency. Results of analysis with electron spectroscopy for chemical analysis show that nitrogen atoms and molybdenum in only the paint film decreased through plasma processing.

Application to cleaning of waste plastic surfaces using atmospheric non-thermal plasma jets

International Nuclear Information System (INIS)

Araya, Masayuki; Yuji, Toshifumi; Watanabe, Takayuki; Kashihara, Junzou; Sumida, Yoshitake

2007-01-01

The removal of paint on the surface of waste plastics is difficult by the conventional process; in this research, a new cleaning mechanism using atmospheric plasmas was examined through optical emission spectroscopy, electron spectroscopy for chemical analysis, and scanning electron microscopy. Results indicate that an increase of pulse frequency enables for a short processing time for the removal of the paint film, signifying that the production of radicals in plasma, especially oxygen radicals, can be controlled by pulse frequency. Plasma jets were generated under the experimental conditions of an input power of 250 W to 400 W, a pulse frequency of 2 kHz to 12 kHz, and a plasma gas flow rate of 30 L/min. Examination of the intensity ratio of the reactive species, as measured by emission spectroscopy, showed that the O/N value increased with an increase in pulse frequency. Results of analysis with electron spectroscopy for chemical analysis show that nitrogen atoms and molybdenum in only the paint film decreased through plasma processing

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.

An ion-sputtering gun to clean crystal surfaces in-situ in an ultra-high-vacuum electron microscope

International Nuclear Information System (INIS)

Morita, Etsuo; Takayanagi, Kunio; Kobayashi, Kunio; Yagi, Katsumichi; Honjo, Goro

1980-01-01

The design and performance of an ion-sputtering gun for cleaning crystal surfaces in-situ in an ultra-high-vacuum electron microscope are reported. The electron microscopic aspects of ion-bombardment damage to ionic magnesium oxide, covalent germanium and silicon, and metallic gold and copper crystals, and the effects of annealing after and during sputtering are described. The growth of various kinds of films deposited in-situ on crystals cleaned by ion-sputtering are described and discussed. (author)

Amorphous Silicon-Germanium Films with Embedded Nano crystals for Thermal Detectors with Very High Sensitivity

International Nuclear Information System (INIS)

Calleja, C.; Torres, A.; Rosales-Quintero, P.; Moreno, M.

2016-01-01

We have optimized the deposition conditions of amorphous silicon-germanium films with embedded nano crystals in a plasma enhanced chemical vapor deposition (PECVD) reactor, working at a standard frequency of 13.56 MHz. The objective was to produce films with very large Temperature Coefficient of Resistance (TCR), which is a signature of the sensitivity in thermal detectors (micro bolometers). Morphological, electrical, and optical characterization were performed in the films, and we found optimal conditions for obtaining films with very high values of thermal coefficient of resistance (TCR = 7.9%K -1 ). Our results show that amorphous silicon-germanium films with embedded nano crystals can be used as thermo sensitive films in high performance infrared focal plane arrays (IRFPAs) used in commercial thermal cameras.

Mapping the electromagnetic field confinement in the gap of germanium nanoantennas with plasma wavelength of 4.5 micrometers

Science.gov (United States)

Calandrini, Eugenio; Venanzi, Tommaso; Appugliese, Felice; Badioli, Michela; Giliberti, Valeria; Baldassarre, Leonetta; Biagioni, Paolo; De Angelis, Francesco; Klesse, Wolfgang M.; Scappucci, Giordano; Ortolani, Michele

2016-09-01

We study plasmonic nanoantennas for molecular sensing in the mid-infrared made of heavily doped germanium, epitaxially grown with a bottom-up doping process and featuring free carrier density in excess of 1020 cm-3. The dielectric function of the 250 nm thick germanium film is determined, and bow-tie antennas are designed, fabricated, and embedded in a polymer. By using a near-field photoexpansion mapping technique at λ = 5.8 μm, we demonstrate the existence in the antenna gap of an electromagnetic energy density hotspot of diameter below 100 nm and confinement volume 105 times smaller than λ3.

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.)

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.)

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.

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.

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

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

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.

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

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

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

Near-Field Imaging of Free Carriers in ZnO Nanowires with a Scanning Probe Tip Made of Heavily Doped Germanium

Science.gov (United States)

Sakat, Emilie; Giliberti, Valeria; Bollani, Monica; Notargiacomo, Andrea; Pea, Marialilia; Finazzi, Marco; Pellegrini, Giovanni; Hugonin, Jean-Paul; Weber-Bargioni, Alexander; Melli, Mauro; Sassolini, Simone; Cabrini, Stefano; Biagioni, Paolo; Ortolani, Michele; Baldassarre, Leonetta

2017-11-01

A novel scanning probe tip made of heavily doped semiconductor is fabricated and used instead of standard gold-coated tips in infrared scattering-type near-field microscopy. Midinfrared near-field microscopy experiments are conducted on ZnO nanowires with a lateral resolution better than 100 nm, using tips made of heavily electron-doped germanium with a plasma frequency in the midinfrared (plasma wavelength of 9.5 μ m ). Nanowires embedded in a dielectric matrix are imaged at two wavelengths, 11.3 and 8.0 μ m , above and below the plasma wavelength of the tips. An opposite sign of the imaging contrasts between the nanowire and the dielectric matrix is observed at the two infrared wavelengths, indicating a clear role of the free-electron plasma in the heavily doped germanium tip in building the imaging contrast. Electromagnetic simulations with a multispherical dipole model accounting for the finite size of the tip are well consistent with the experiments. By comparison of the simulated and measured imaging contrasts, an estimate for the local free-carrier density in the investigated ZnO nanowires in the low 1019 cm-3 range is retrieved. The results are benchmarked against the scattering intensity and phase maps obtained on the same sample with a gold-coated probe tip in pseudoheterodyne detection mode.

Simultaneous specimen and stage cleaning device for analytical electron microscope

Science.gov (United States)

Zaluzec, Nestor J.

1996-01-01

An improved method and apparatus are provided for cleaning both a specimen stage, a specimen and an interior of an analytical electron microscope (AEM). The apparatus for cleaning a specimen stage and specimen comprising a plasma chamber for containing a gas plasma and an air lock coupled to the plasma chamber for permitting passage of the specimen stage and specimen into the plasma chamber and maintaining an airtight chamber. The specimen stage and specimen are subjected to a reactive plasma gas that is either DC or RF excited. The apparatus can be mounted on the analytical electron microscope (AEM) for cleaning the interior of the microscope.

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)

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.

Rapid and simple clean-up and derivatizaton procedure for the gas chromatographic determination of acidic drugs in plasma

NARCIS (Netherlands)

Roseboom, H.; Hulshoff, A.

1979-01-01

A rapid and simple clean-up and derivatization procedure that can be generally applied to the gas chromatographie (GC) determination of acidic drugs of various chemical and therapeutic classes is described. The drugs are extracted from acidified plasma with chloroform containing 5% of isopropanol,

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

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.

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.

Flexible small size radiofrequency plasma torch for Tokamak wall cleaning

International Nuclear Information System (INIS)

Eusebiu-Rosini Ionita; Luciu, I.; Dinescu, G.; Grisolia, Ch.

2006-01-01

Tritium accumulation in walls is a limiting factor in efficient long term operation of fusion machines. A number of detritiation techniques are under study, like laser, discharge, flash lamp based cleaning. One of the encountered difficulties is the limited access of the detritiation tool in narrow spaces, as in divertor region, inter-tiles or inside castellated gaps, where in fact an enhanced co-deposition and tritium trapping were observed. This contribution addresses the problem of elaboration of plasma torch as a tool appropriate for stimulating detritiation and removal of co-deposited layers in such spaces. The requirements imposed to the plasma torch source were related to the compatibility with inside torus operation: small diameter in order to permit access in narrow spaces, reasonable power, large range of working pressures from vacuum to atmosphere, closed loop cooling, flexibility in order to allow scanning and mounting on a robotic arm. The approached design is based on a radiofrequency discharge constricted to burn in a closed space between an active radiofrequency electrode and a grounded nozzle, from where plasma expands outside as a directional beam. The found solutions have led to a flexible hand held source working stable up to 300 W injected power and consisting of a cylindrical body of 20 mm diameter including the external water jacket embracing the discharge and an inside cooling circuit. The electrical characterization of the radiofrequency discharge sustaining the expanded plasma was performed and the domain of stable source operation in terms of power, current, pressure, argon mass flow rate is presented and discussed. The plasma beam size presents a strong dependence on pressure: the plasma length decreases from 200 mm to 20 mm, when pressure increases from vacuum to atmospheric, depending on power and mass flow rate. The ionized gas temperature, as indicated by a thermocouple head inserted in expansion in the nozzle proximity fall in the

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)

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.

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)

An environmentally-friendly vacuum reduction metallurgical process to recover germanium from coal fly ash

Energy Technology Data Exchange (ETDEWEB)

Zhang, Lingen; Xu, Zhenming, E-mail: zmxu@sjtu.edu.cn

2016-07-15

Highlights: • An environmental friendly vacuum reduction metallurgical process is proposed. • Rare and valuable metal germanium from coal fly ash is recycled. • Residues are not a hazardous material and can be further recycled. • A germanium recovery ratio of 94.64% is obtained in pilot scale experiments. - Abstract: The demand for germanium in the field of semiconductor, electronics, and optical devices is growing rapidly; however, the resources of germanium are scarce worldwide. As a secondary material, coal fly ash could be further recycled to retrieve germanium. Up to now, the conventional processes to recover germanium have two problems as follows: on the one hand, it is difficult to be satisfactory for its economic and environmental effect; on the other hand, the recovery ratio of germanium is not all that could be desired. In this paper, an environmentally-friendly vacuum reduction metallurgical process (VRMP) was proposed to recover germanium from coal fly ash. The results of the laboratory scale experiments indicated that the appropriate parameters were 1173 K and 10 Pa with 10 wt% coke addition for 40 min, and recovery ratio germanium was 93.96%. On the basis of above condition, the pilot scale experiments were utilized to assess the actual effect of VRMP for recovery of germanium with parameter of 1473 K, 1–10 Pa and heating time 40 min, the recovery ratio of germanium reached 94.64%. This process considerably enhances germanium recovery, meanwhile, eliminates much of the water usage and residue secondary pollution compared with other conventional processes.

Temporal feature of X-ray laser plasma observed from 3ω0/2, 2ω0 harmonic emission

International Nuclear Information System (INIS)

Li Wenhong; Mei Qiyong; Zhao Xuewei; Chen Yuting; Chunyu Shutai

1995-01-01

Temporal feature of X-ray laser plasma density was observed from 3ω 0 /2, 2ω 0 harmonic emission in the experiments. The temporal feature of 3ω 0 /2 harmonic emission of the germanium film is much different from that of the slab germanium target. The production of x-ray laser is closely related to 3ω 0 /2 harmonic emission in the slab germanium targets

Plasma phase transition in dense hydrogen and electron-hole plasmas

CERN Document Server

Filinov, V S; Levashov, P R; Fortov, V E; Ebeling, W; Schlanges, M; Koch, S W

2003-01-01

Plasma phase transitions in dense hydrogen and electron-hole plasmas are investigated by direct path integral Monte Carlo methods. The phase boundary of the electron-hole liquid in germanium is calculated and is found to agree reasonably well with the known experimental results. Analogous behaviour is found for high-density hydrogen. For a temperature of T = 10 000 K it is shown that the internal energy is lowered due to droplet formation for densities between 10 sup 2 sup 3 cm sup - sup 3 and 10 sup 2 sup 4 cm sup - sup 3.

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.

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

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

Impurity studies and discharge cleaning in Doublet III

Energy Technology Data Exchange (ETDEWEB)

Marcus, F.B.

1979-10-01

The goal of present and next generation tokamak experiments is to produce high-density, high-purity plasmas during high-power, extended-duration discharges. Plasma discharges with Z/sub eff/ values near unity and low concentrations of medium and high-Z metallic impurities have been obtained in Doublet III using a combination of low-power hydrogen discharge cleaning, gas puffing, precise plasma shape and position control, and high-Z limiters. Analysis of the first wall surface and residual gas impurities confirmed that clean conditions have been achieved. The high-Z limiters showed very limited amounts of melting or arcing. The progress of the wall cleaning process was monitored by three diagnostic techniques: Auger electron spectroscopy of metallic samples at the vessel wall, residual gas analysis, and the resistivity of full power discharges.

Impurity studies and discharge cleaning in Doublet III

International Nuclear Information System (INIS)

Marcus, F.B.

1979-10-01

The goal of present and next generation tokamak experiments is to produce high-density, high-purity plasmas during high-power, extended-duration discharges. Plasma discharges with Z/sub eff/ values near unity and low concentrations of medium and high-Z metallic impurities have been obtained in Doublet III using a combination of low-power hydrogen discharge cleaning, gas puffing, precise plasma shape and position control, and high-Z limiters. Analysis of the first wall surface and residual gas impurities confirmed that clean conditions have been achieved. The high-Z limiters showed very limited amounts of melting or arcing. The progress of the wall cleaning process was monitored by three diagnostic techniques: Auger electron spectroscopy of metallic samples at the vessel wall, residual gas analysis, and the resistivity of full power discharges

Development of in situ cleaning techniques for diagnostic mirrors in ITER

International Nuclear Information System (INIS)

Litnovsky, A.; Laengner, M.; Matveeva, M.; Schulz, Ch.; Marot, L.; Voitsenya, V.S.; Philipps, V.; Biel, W.; Samm, U.

2011-01-01

Mirrors will be used in all optical and laser-based diagnostic systems of ITER. In the severe environment, the optical characteristics of mirrors will be degraded, hampering the entire performance of the respective diagnostics. A minute impurity deposition of 20 nm of carbon on the mirror is sufficient to decrease the mirror reflectivity by tens of percent outlining the necessity of the mirror cleaning in ITER. The results of R and D on plasma cleaning of molybdenum diagnostic mirrors are reported. The mirrors contaminated with amorphous carbon films in the laboratory conditions and in the tokamaks were cleaned in steady-state hydrogenic plasmas. The maximum cleaning efficiency of 4.2 nm/min was reached for the laboratory and soft tokamak hydrocarbon films, whereas for the hard tokamak films the carbidization of mirrors drastically decreased the cleaning efficiency down to 0.016 nm/min. This implies the necessity of sputtering cleaning of contaminated mirrors as the only reliable tool to remove the deposits by plasma cleaning. An overview of R and D program on mirror cleaning is provided along with plans for further studies and the recommendations for ITER mirror-based diagnostics.

Long-term impact of radiation on plasma concentrations of cytokines (IL-1 and IL-6) and adhesion molecules (ICAM-1 and P-selectin) in Chernobyl clean-up workers from Latvia

International Nuclear Information System (INIS)

Kurjane, N.; Kirsfinks, M.; Hagina, E.; Socnevs, A.

2001-01-01

Study was undertaken to evaluate plasma concentrations of interleukin-1beta (IL-1), interleukin-6 (IL-6), and adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1) and P-selectin in persons who participated in the clean-up work of the Chernobyl NPP explosion aftereffects. 40 Chernobyl clean-up workers suffering from most common neurological diseases - polyneuropathy and encephalopathy, and 40 healthy blood donors were analyzed for plasma levels of IL-6, IL1-β, sICAM-1 and sP-selectin 13 years after the accident. The documented external radiation dosage to the investigated Chernobyl clean-up workers was exposed from 0,009 to 0,28 Gy. Significantly elevated plasma concentrations of IL-6 and P-selectin but not of IL-1β were found in Chernobyl clean-up labourers as compared to those in healthy blood donors. (p<0.01). There was no obvious association of cytokine and adhesion molecule levels with radiation doses, as individuals working in the Chernobyl area in 1986 at a time when the external radiation exposure was higher revealed similar plasma concentrations if compared to those of a later period of time (1987-1990). (authors)

Comparison of glow discharge cleaning with Taylor-type discharge cleaning on JFT-2

International Nuclear Information System (INIS)

Yokokura, Kenji; Matsuzaki, Yoshimi; Tani, Takashi

1983-01-01

Method of glow discharge cleaning (GDC) was applied to JFT-2 tokamak and the cleaning effect of GDC was compared with that of taylor-type discharge cleaning (TDC) on the same machin. Results show clearly their individual characteristics to remove light impurities. Their abilities of surface cleaning were compared each other by observing cleanliness of sample surfaces with a AES and by measuring decay times of produced gas pressures during discharge cleanings with a mass-analyser. It was shown that TDC method is better by several times than GDC method from a mass-analyser measurement. Moreover discharge cleaning time necessary to reduce light impurities in the normal plasma to a certain level was compared by monitoring time evolution of radiation loss power with a bolometer, and the time by TDC was only one fifth of that by GDC. The advantage of TDC may come from the excellently high hydrogen flux which interacts with the limiter and the wall. (author)

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.

Plasma cleaning of beamline optical components: Contamination and gas composition effects

International Nuclear Information System (INIS)

Rosenberg, R.A.; Smith, J.A.; Wallace, D.J.

1992-01-01

We have initiated a program to study the impact of gas composition on the carbon removal rate during plasma cleaning of optical components, and of possible contamination due to the plasma processing. The measurements were performed in a test chamber designed to simulate the geometry of the grating/Codling mirror section of a Grasshopper monochromator. Removal rates were determined for a direct-current (dc) (Al electrode) discharge using a quartz crystal microbalance coated with polymethylmethacrylate, located at the position of the grating. Auger electron spectroscopy analysis of strateg- ically located, gold-coated stainless steel samples was employed to determine contamination. The relative removal rates of the gases studied were 3% C 2 F 6 /O 2 much-gt O 2 +H 2 O>O 2 ∼N 2 O>H 2 >N 2 . Although the C 2 F 6 /O 2 gas mixture showed a 20 times greater removal rate than its nearest competitor, it also caused significant contamination to occur. Contamination studies were performed for both dc and radio-frequency (rf) discharges. For the dc discharge we found that great care must be taken in order to avoid Al contamination; for the rf discharge, significant Fe contamination was observed

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.

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

Bandgap-customizable germanium using lithographically determined biaxial tensile strain for silicon-compatible optoelectronics.

Science.gov (United States)

Sukhdeo, David S; Nam, Donguk; Kang, Ju-Hyung; Brongersma, Mark L; Saraswat, Krishna C

2015-06-29

Strain engineering has proven to be vital for germanium-based photonics, in particular light emission. However, applying a large permanent biaxial tensile strain to germanium has been a challenge. We present a simple, CMOS-compatible technique to conveniently induce a large, spatially homogenous strain in circular structures patterned within germanium nanomembranes. Our technique works by concentrating and amplifying a pre-existing small strain into a circular region. Biaxial tensile strains as large as 1.11% are observed by Raman spectroscopy and are further confirmed by photoluminescence measurements, which show enhanced and redshifted light emission from the strained germanium. Our technique allows the amount of biaxial strain to be customized lithographically, allowing the bandgaps of different germanium structures to be independently customized in a single mask process.

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

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....

Alternative Solvents and Technologies for Precision Cleaning of Aerospace Components

Science.gov (United States)

Grandelli, Heather; Maloney, Phillip; DeVor, Robert; Hintze, Paul

2014-01-01

Precision cleaning solvents for aerospace components and oxygen fuel systems, including currently used Vertrel-MCA, have a negative environmental legacy, high global warming potential, and have polluted cleaning sites. Thus, alternative solvents and technologies are being investigated with the aim of achieving precision contamination levels of less than 1 mg/sq ft. The technologies being evaluated are ultrasonic bath cleaning, plasma cleaning and supercritical carbon dioxide cleaning.

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.

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

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.

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

Segmentation of the Outer Contact on P-Type Coaxial Germanium Detectors

Energy Technology Data Exchange (ETDEWEB)

Hull, Ethan L.; Pehl, Richard H.; Lathrop, James R.; Martin, Gregory N.; Mashburn, R. B.; Miley, Harry S.; Aalseth, Craig E.; Hossbach, Todd W.

2006-09-21

Germanium detector arrays are needed for low-level counting facilities. The practical applications of such user facilities include characterization of low-level radioactive samples. In addition, the same detector arrays can also perform important fundamental physics measurements including the search for rare events like neutrino-less double-beta decay. Coaxial germanium detectors having segmented outer contacts will provide the next level of sensitivity improvement in low background measurements. The segmented outer detector contact allows performance of advanced pulse shape analysis measurements that provide additional background reduction. Currently, n-type (reverse electrode) germanium coaxial detectors are used whenever a segmented coaxial detector is needed because the outer boron (electron barrier) contact is thin and can be segmented. Coaxial detectors fabricated from p-type germanium cost less, have better resolution, and are larger than n-type coaxial detectors. However, it is difficult to reliably segment p-type coaxial detectors because thick (~1 mm) lithium-diffused (hole barrier) contacts are the standard outside contact for p-type coaxial detectors. During this Phase 1 Small Business Innovation Research (SBIR) we have researched the possibility of using amorphous germanium contacts as a thin outer contact of p-type coaxial detectors that can be segmented. We have developed amorphous germanium contacts that provide a very high hole barrier on small planar detectors. These easily segmented amorphous germanium contacts have been demonstrated to withstand several thousand volts/cm electric fields with no measurable leakage current (<1 pA) from charge injection over the hole barrier. We have also demonstrated that the contact can be sputter deposited around and over the curved outside surface of a small p-type coaxial detector. The amorphous contact has shown good rectification properties on the outside of a small p-type coaxial detector. These encouraging

Dual Electrolytic Plasma Processing for Steel Surface Cleaning and Passivation

Science.gov (United States)

Yang, L.; Zhang, P.; Shi, J.; Liang, J.; Tian, W. B.; Zhang, Y. M.; Sun, Z. M.

2017-10-01

To remove the rust on rebars and passivate the fresh surfaces, electrodes reversing electrolytic plasma processing (EPP) was proposed and conducted in a 10 wt.% Na2CO3 aqueous solution. The morphology and the composition of the surface were investigated by SEM and XPS. Experimental results show that the rust on the surface was removed effectively by cathode EPP, and a passive film containing Cr2O3 was achieved by the succeeding anode EPP treatment, by a simple operation of reversing the bias. The corrosion resistance was evaluated in a 3.5 wt.% NaCl aqueous solution using an electrochemical workstation. In comparison, the corrosion resistance was improved by the succeeding anode EPP treatment, which is evidenced by a positive shift of the open-circuit potential, an increase in the electrochemical impedance representing the inner layer by 76.8% and the decrease in the corrosion current density by 49.6%. This is an effective and environment-friendly technique to clean and passivate rebars and similar steel materials.

Clean coal technologies

International Nuclear Information System (INIS)

Aslanyan, G.S.

1993-01-01

According to the World Energy Council (WEC), at the beginning of the next century three main energy sources - coal, nuclear power and oil will have equal share in the world's total energy supply. This forecast is also valid for the USSR which possesses more than 40% of the world's coal resources and continuously increases its coal production (more than 700 million tons of coal are processed annually in the USSR). The stringent environmental regulations, coupled with the tendency to increase the use of coal are the reasons for developing different concepts for clean coal utilization. In this paper, the potential efficiency and environmental performance of different clean coal production cycles are considered, including technologies for coal clean-up at the pre-combustion stage, advanced clean combustion methods and flue gas cleaning systems. Integrated systems, such as combined gas-steam cycle and the pressurized fluidized bed boiler combined cycle, are also discussed. The Soviet National R and D program is studying new methods for coal utilization with high environmental performance. In this context, some basic research activities in the field of clean coal technology in the USSR are considered. Development of an efficient vortex combustor, a pressurized fluidized bed gasifier, advanced gas cleaning methods based on E-beam irradiation and plasma discharge, as well as new catalytic system, are are presented. In addition, implementation of technological innovations for retrofitting and re powering of existing power plants is discussed. (author)

Coexistence in even-even nuclei with emphasis on the germanium isotopes

International Nuclear Information System (INIS)

Carchidi, M.A.V.

1985-01-01

No simple model to date can explain in a self-consistent way the results of direct transfer data and BE2 electromagnetic rates in the germanium isotopes. The simplest models use a two-state interaction for describing the ground state and first excited O + state. In all cases, these models can account for some of the data, but they are in drastic conflict with other experimental measurements. In this thesis, it is shown that a two-state model can consistently account for two-neutron and alpha transfer O + 2 /g.s. cross-section ratio data in the germanium region (ie. zinc, germanium, and selenium), proton occupation number data in the ground states of the even stable zinc, germanium, and selenium isotopes, and BE2 transition rates in isotopes of germanium and zinc. In addition the author can account for most of the one-neutron and two-neutron transfer O + 2 /g.s. and (9/2 + 2 )/(9/2 + 1 ) cross-section ratio data in the odd-mass germanium isotopes. In this generalized two-state model (called Rerg1), the author makes as few assumptions as possible about the nature of the basis states; rather the author allows the experimental data to dictate the properties of the basis-state overlaps. In this sense, the author has learned much about the basis states and has a useful tool for constructing them. The author also shows that the Rerg1 model can quantitatively account for all two-neutron O + 2 /g.s. cross-section ratio data in all even-even nuclei from calcium to uranium

Aluminum metal surface cleaning and activation by atmospheric-pressure remote plasma

Energy Technology Data Exchange (ETDEWEB)

Muñoz, J., E-mail: jmespadero@uco.es; Bravo, J.A.; Calzada, M.D.

2017-06-15

Highlights: • Atmospheric-pressure postdischarges have been applied on aluminium surfaces. • The outer hydrocarbon layer is reduced by the action of the postdischarge. • The treatment promotes the appearance of hydrophilic OH radicals in the surface. • Effectivity for distances up to 5 cm allows for treating irregular surfaces. • Ageing in air due to the disappearance of OH radicals has been reported. - Abstract: The use of the remote plasma (postdischarge) of argon and argon-nitrogen microwave plasmas for cleaning and activating the surface of metallic commercial aluminum samples has been studied. The influence of the nitrogen content and the distance between the treated samples and the end of the discharge on the hydrophilicity and the surface energy has been analyzed by means of the sessile drop technique and the Owens-Wendt method. A significant increase in the hydrophilicity has been noted in the treated samples, together with an increase in the surface energy from values around 37 mJ/m{sup 2} to 77 mJ/m{sup 2}. Such increase weakly depends on the nitrogen content of the discharge, and the effectivity of the treatment extends to distances up to 5 cm from the end of the discharge, much longer than those reported in other plasma-based treatments. The analysis of the treated samples using X-ray photoelectron spectroscopy reveals that such increase in the surface energy takes place due to a reduction of the carbon content and an increase in the amount of OH radicals in the surface. These radicals tend to disappear within 24–48 h after the treatment when the samples are stored in contact with ambient air, resulting in the ageing of the treated surface and a partial retrieval of the hydrophobicity of the surface.

Techniques to distinguish between electron and photon induced events using segmented germanium detectors

International Nuclear Information System (INIS)

Kroeninger, K.

2007-01-01

Two techniques to distinguish between electron and photon induced events in germanium detectors were studied: (1) anti-coincidence requirements between the segments of segmented germanium detectors and (2) the analysis of the time structure of the detector response. An 18-fold segmented germanium prototype detector for the GERDA neutrinoless double beta-decay experiment was characterized. The rejection of photon induced events was measured for the strongest lines in 60 Co, 152 Eu and 228 Th. An accompanying Monte Carlo simulation was performed and the results were compared to data. An overall agreement with deviations of the order of 5-10% was obtained. The expected background index of the GERDA experiment was estimated. The sensitivity of the GERDA experiment was determined. Special statistical tools were developed to correctly treat the small number of events expected. The GERDA experiment uses a cryogenic liquid as the operational medium for the germanium detectors. It was shown that germanium detectors can be reliably operated through several cooling cycles. (orig.)

Techniques to distinguish between electron and photon induced events using segmented germanium detectors

Energy Technology Data Exchange (ETDEWEB)

Kroeninger, K.

2007-06-05

Two techniques to distinguish between electron and photon induced events in germanium detectors were studied: (1) anti-coincidence requirements between the segments of segmented germanium detectors and (2) the analysis of the time structure of the detector response. An 18-fold segmented germanium prototype detector for the GERDA neutrinoless double beta-decay experiment was characterized. The rejection of photon induced events was measured for the strongest lines in {sup 60}Co, {sup 152}Eu and {sup 228}Th. An accompanying Monte Carlo simulation was performed and the results were compared to data. An overall agreement with deviations of the order of 5-10% was obtained. The expected background index of the GERDA experiment was estimated. The sensitivity of the GERDA experiment was determined. Special statistical tools were developed to correctly treat the small number of events expected. The GERDA experiment uses a cryogenic liquid as the operational medium for the germanium detectors. It was shown that germanium detectors can be reliably operated through several cooling cycles. (orig.)

High-resolution imaging gamma-ray spectroscopy with externally segmented germanium detectors

Science.gov (United States)

Callas, J. L.; Mahoney, W. A.; Varnell, L. S.; Wheaton, W. A.

1993-01-01

Externally segmented germanium detectors promise a breakthrough in gamma-ray imaging capabilities while retaining the superb energy resolution of germanium spectrometers. An angular resolution of 0.2 deg becomes practical by combining position-sensitive germanium detectors having a segment thickness of a few millimeters with a one-dimensional coded aperture located about a meter from the detectors. Correspondingly higher angular resolutions are possible with larger separations between the detectors and the coded aperture. Two-dimensional images can be obtained by rotating the instrument. Although the basic concept is similar to optical or X-ray coded-aperture imaging techniques, several complicating effects arise because of the penetrating nature of gamma rays. The complications include partial transmission through the coded aperture elements, Compton scattering in the germanium detectors, and high background count rates. Extensive electron-photon Monte Carlo modeling of a realistic detector/coded-aperture/collimator system has been performed. Results show that these complicating effects can be characterized and accounted for with no significant loss in instrument sensitivity.

Oriented bottom-up growth of armchair graphene nanoribbons on germanium

Science.gov (United States)

Arnold, Michael Scott; Jacobberger, Robert Michael

2016-03-15

Graphene nanoribbon arrays, methods of growing graphene nanoribbon arrays and electronic and photonic devices incorporating the graphene nanoribbon arrays are provided. The graphene nanoribbons in the arrays are formed using a scalable, bottom-up, chemical vapor deposition (CVD) technique in which the (001) facet of the germanium is used to orient the graphene nanoribbon crystals along the [110] directions of the germanium.

Germanium field-effect transistor made from a high-purity substrate

International Nuclear Information System (INIS)

Hansen, W.L.; Goulding, F.S.; Haller, E.E.

1978-11-01

Field effect transistors have been fabricated on high-purity germanium substrates using low-temperature technology. The aim of this work is to preserve the low density of trapping centers in high-quality starting material by low-temperature ( 0 C) processing. The use of germanium promises to eliminate some of the traps which cause generation-recombination noise in silicon field-effect transistors (FET's) at low temperatures. Typically, the transconductance (g/sub m/) in the germanium FET's is 10 mA/V and the gate leakage can be less than 10 -12 A. Present devices exhibit a large 1/f noise component and most of this noise must be eliminated if they are to be competitive with silicon FET's commonly used in high-resolution nuclear spectrometers

Dry efficient cleaning of poly-methyl-methacrylate residues from graphene with high-density H{sub 2} and H{sub 2}-N{sub 2} plasmas

Energy Technology Data Exchange (ETDEWEB)

Cunge, G., E-mail: gilles.cunge@cea.fr; Petit-Etienne, C.; Davydova, A. [Laboratoire des Technologies de la Microélectronique, CNRS-UJF, 17 rue des Martyrs, 38054 Grenoble (France); Ferrah, D.; Renault, O. [CEA, LETI, MINATEC, 17 rue des Martyrs, 38054 Grenoble (France); Okuno, H. [CEA, INAC/SP2M/LEMMA, 17 rue des Martyrs, 38054 Grenoble (France); Kalita, D.; Bouchiat, V. [Institut Néel, CNRS-UJF-INP, BP 166, 38042 Grenoble Cedex 9 (France)

2015-09-28

Graphene is the first engineering electronic material, which is purely two-dimensional: it consists of two exposed sp{sup 2}-hybridized carbon surfaces and has no bulk. Therefore, surface effects such as contamination by adsorbed polymer residues have a critical influence on its electrical properties and can drastically hamper its widespread use in devices fabrication. These contaminants, originating from mandatory technological processes of graphene synthesis and transfer, also impact fundamental studies of the electronic and structural properties at the atomic scale. Therefore, graphene-based technology and research requires “soft” and selective surface cleaning techniques dedicated to limit or to suppress this surface contamination. Here, we show that a high-density H{sub 2} and H{sub 2}-N{sub 2} plasmas can be used to selectively remove polymeric residues from monolayer graphene without any damage on the graphene surface. The efficiency of this dry-cleaning process is evidenced unambiguously by a set of spectroscopic and microscopic methods, providing unprecedented insights on the cleaning mechanisms and highlighting the role of specific poly-methyl-methacrylate residues at the graphene interface. The plasma is shown to perform much better cleaning than solvents and has the advantage to be an industrially mature technology adapted to large area substrates. The process is transferable to other kinds of two-dimensional material and heterostructures.

Multiphysical simulation analysis of the dislocation structure in germanium single crystals

Science.gov (United States)

Podkopaev, O. I.; Artemyev, V. V.; Smirnov, A. D.; Mamedov, V. M.; Sid'ko, A. P.; Kalaev, V. V.; Kravtsova, E. D.; Shimanskii, A. F.

2016-09-01

To grow high-quality germanium crystals is one of the most important problems of growth industry. The dislocation density is an important parameter of the quality of single crystals. The dislocation densities in germanium crystals 100 mm in diameter, which have various shapes of the side surface and are grown by the Czochralski technique, are experimentally measured. The crystal growth is numerically simulated using heat-transfer and hydrodynamics models and the Alexander-Haasen dislocation model in terms of the CGSim software package. A comparison of the experimental and calculated dislocation densities shows that the dislocation model can be applied to study lattice defects in germanium crystals and to improve their quality.

γ-ray tracking in germanium: the backtracking method

International Nuclear Information System (INIS)

Marel, J. van der; Cederwall, B.

2002-01-01

In the framework of a European TMR network project the concept for a γ-ray tracking array is being developed for nuclear physics spectroscopy in the energy range of ∼10 keV up to several MeV. The tracking array will consist of a large number of position-sensitive germanium detectors in a spherical geometry around a target. Due to the high segmentation, a Compton scattered γ-ray will deposit energy in several different segments. A method has been developed to reconstruct the tracks of multiple coincident γ-rays and to find their initial energies. By starting from the final point the track can be reconstructed backwards to the origin with the help of the photoelectric and Compton cross-sections and the Compton scatter formula. Every reconstructed track is given a figure of merit, thus allowing suppression of wrongly reconstructed tracks and γ-rays that have scattered out of the detector system. This so-called backtracking method has been tested on simulated events in a shell-like geometry for germanium and in planar geometries for silicon, germanium and CdTe

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.)

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.)

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

Quantum interference magnetoconductance of polycrystalline germanium films in the variable-range hopping regime

Science.gov (United States)

Li, Zhaoguo; Peng, Liping; Zhang, Jicheng; Li, Jia; Zeng, Yong; Zhan, Zhiqiang; Wu, Weidong

2018-06-01

Direct evidence of quantum interference magnetotransport in polycrystalline germanium films in the variable-range hopping (VRH) regime is reported. The temperature dependence of the conductivity of germanium films fulfilled the Mott VRH mechanism with the form of ? in the low-temperature regime (?). For the magnetotransport behaviour of our germanium films in the VRH regime, a crossover, from negative magnetoconductance at the low-field to positive magnetoconductance at the high-field, is observed while the zero-field conductivity is higher than the critical value (?). In the regime of ?, the magnetoconductance is positive and quadratic in the field for some germanium films. These features are in agreement with the VRH magnetotransport theory based on the quantum interference effect among random paths in the hopping process.

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)

Strain distribution in single, suspended germanium nanowires studied using nanofocused x-rays

DEFF Research Database (Denmark)

Keplinger, Mario; Grifone, Raphael; Greil, Johannes

2016-01-01

Within the quest for direct band-gap group IV materials, strain engineering in germanium is one promising route. We present a study of the strain distribution in single, suspended germanium nanowires using nanofocused synchrotron radiation. Evaluating the probed Bragg reflection for different ill...

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.

Baking and helium glow discharge cleaning of SST-1 tokamak with graphite plasma facing components

International Nuclear Information System (INIS)

Semwal, Pratibha; Khan, Ziauddin; Raval, Dilip

2015-01-01

Graphite plasma facing components (PFCs) were installed inside SST-1 vacuum vessel. Prior to installation, all the graphite tiles were baked at 1000 °C in a vacuum furnace operated below 1.0 X 10 -5 mbar. However due to the porous structure of graphite, they absorb a significant amount of water vapour from air during the installation process. Rapid desorption of water vapour requires high temperature bake-out of the PFCs at ≥ 250 °C. In SST-1 the PFCs were baked at 250 °C using hot nitrogen gas facility to remove the absorbed water vapour. Also device with large graphite surface area has the disadvantage that a large quantity of hydrogen gets trapped inside it during plasma discharges which makes density control difficult. Helium (He) glow discharge cleaning (GDC) effectively removes this stored hydrogen as well as other impurities like oxygen and hydrocarbon within few nanometers from the surface by particle induced desorption. Before plasma operation in SST-1 tokamak, both baking of PFCs and He-GDC were carried out so that these impurities were removed effectively. The mean desorption yield of hydrogen was found to be 0.48. In this paper, the results of effect of baking and He-GDC experiments of SST-1 will be presented in detail. (author)

Baking and helium glow discharge cleaning of SST-1 Tokamak with graphite plasma facing components

Science.gov (United States)

Semwal, P.; Khan, Z.; Raval, D. C.; Dhanani, K. R.; George, S.; Paravastu, Y.; Prakash, A.; Thankey, P.; Ramesh, G.; Khan, M. S.; Saikia, P.; Pradhan, S.

2017-04-01

Graphite plasma facing components (PFCs) were installed inside the SST-1 vacuum vessel. Prior to installation, all the graphite tiles were baked at 1000 °C in a vacuum furnace operated below 1.0 × 10-5 mbar. However due to the porous structure of graphite, they absorb a significant amount of water vapour from air during the installation process. Rapid desorption of this water vapour requires high temperature bake-out of the PFCs at ≥ 250 °C. In SST-1 the PFCs were baked at 250 °C using hot nitrogen gas facility to remove the absorbed water vapour. Also device with large graphite surface area has the disadvantage that a large quantity of hydrogen gets trapped inside it during plasma discharges which makes density control difficult. Helium glow discharge cleaning (He-GDC) effectively removes this stored hydrogen as well as other impurities like oxygen and hydrocarbon within few nano-meters from the surface by particle induced desorption. Before plasma operation in SST-1 tokamak, both baking of PFCs and He-GDC were carried out so that these impurities were removed effectively. The mean desorption yield of hydrogen was found to be 0.24. In this paper the results of baking and He-GDC experiments of SST-1 will be presented in detail.

Raman enhancement on ultra-clean graphene quantum dots produced by quasi-equilibrium plasma-enhanced chemical vapor deposition.

Science.gov (United States)

Liu, Donghua; Chen, Xiaosong; Hu, Yibin; Sun, Tai; Song, Zhibo; Zheng, Yujie; Cao, Yongbin; Cai, Zhi; Cao, Min; Peng, Lan; Huang, Yuli; Du, Lei; Yang, Wuli; Chen, Gang; Wei, Dapeng; Wee, Andrew Thye Shen; Wei, Dacheng

2018-01-15

Graphene is regarded as a potential surface-enhanced Raman spectroscopy (SERS) substrate. However, the application of graphene quantum dots (GQDs) has had limited success due to material quality. Here, we develop a quasi-equilibrium plasma-enhanced chemical vapor deposition method to produce high-quality ultra-clean GQDs with sizes down to 2 nm directly on SiO 2 /Si, which are used as SERS substrates. The enhancement factor, which depends on the GQD size, is higher than conventional graphene sheets with sensitivity down to 1 × 10 -9  mol L -1 rhodamine. This is attributed to the high-quality GQDs with atomically clean surfaces and large number of edges, as well as the enhanced charge transfer between molecules and GQDs with appropriate diameters due to the existence of Van Hove singularities in the electronic density of states. This work demonstrates a sensitive SERS substrate, and is valuable for applications of GQDs in graphene-based photonics and optoelectronics.

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

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.

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...

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.

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

Ultraviolet-light-induced processes in germanium-doped silica

DEFF Research Database (Denmark)

Kristensen, Martin

2001-01-01

A model is presented for the interaction of ultraviolet (UV) light with germanium-doped silica glass. It is assumed that germanium sites work as gates for transferring the excitation energy into the silica. In the material the excitation induces forbidden transitions to two different defect states...... which are responsible for the observed refractive index changes. Activation energies [1.85 +/-0.15 eV and 1.91 +/-0.15 eV] and rates [(2.7 +/-1.9) x 10(13) Hz and(7.2 +/-4.5) x 10(13) Hz] are determined for thermal elimination of these states. Good agreement is found with experimental results and new UV...

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

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.

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.)

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.)

Experiments on cleaning effects of TDC, GDC and ECR-DC in the JFT-2M tokamak

International Nuclear Information System (INIS)

Matsuzaki, Y.; Ogawa, H.; Miura, Y.; Ohtsuka, H.; Suzuki, N.; Yamauchi, T.; Tani, T.; Mori, M.

1987-01-01

The cleaning effects of Taylor-type discharge cleaning (TDC), glow discharge cleaning (GDC) and ECR discharge cleaning (ECR-DC) were studied in the JFT-2M tokamak by comparing the properties of resulting tokamak plasmas, by observing the surface composition of samples and by residual gas analysis. The operational parameters of the three discharge cleaning techniques were as follows; the plasma current for TDC is 20 kA, the DC current for GDC is 3 A and the RF power for ECR-DC is 2.3 kW. Parameters of the tokamak plasmas such as loop voltages, radiation losses, spectra emission of oxygen, maximum mean electron densities and profiles of electron temperature were improved as the TDC and ECR-DC proceeded. Changes in the surface composition of samples were measured by Auger electron spectrosopy. The results showed that during the TDC and ECR-DC oxygen was reduced, while GDC reduced mainly carbon. Residual gas analysis performed during discharge cleaning corroborated these results. (orig.)

A study on the forms of existence of germanium in uranium-bearing coals of Bangmai basin of Yunnan

International Nuclear Information System (INIS)

Zhang Shuling; Wang Shuying; Yin Jinshuang

1988-07-01

The Bangmai basin is an asymmetrical intermontane synclinal basin with a Hercynian-Yenshan granitic body (γ 3 3 -γ 5 2 ) as its basement. Its overlying strata are made up of the N 1 of coal-bearing clastic rocks of Neogene period. Germanium ore mostly occur within the N 1 2 coal-seam. Uranium, germanium-bearing coals are mainly lignites of low grade in coalation and belong to semidurain, semiclarain, duroclarain and clarodurain. In order to probe into the forms of existence of germanium in coal, six kinds of analytical methods (electronic probe analysis, separation of heavy liquid, grain-size analysis, electric osmosis, chemical extraction and grade-extraction) have been adopted. A simulated test of humic complex germanium in the laboratory was carried out. According to infrared spectral analysis, it is found that 1700 cm -1 wavecrest almost disappears, 1250 cm -1 peak weakens and 1600 cm -1 peak strengthens, 1400 cm -1 peak slightly strengthens. No doubt, these illustrate the formatiion of humic germanium complex. Afterward, through differential thermal analysis and measurement of pH variation of media, it futher proves the presence of humic germanium complex. It is considered that the forms of existence of germanium in uranium-bearing coals mainly are: (1) In close chemical combination with organic matter, usually in the form of humic germanium complex and germanium organic compound; (2) In the state of adsorption, germanium is adsorbed by some organic matter, clay minerals and limonite etc.; (3) A very rare part occurring as isomorphous form

Baking and helium glow discharge cleaning of SST-1 Tokamak with graphite plasma facing components

International Nuclear Information System (INIS)

Semwal, P; Khan, Z; Raval, D C; Dhanani, K R; George, S; Paravastu, Y; Prakash, A; Thankey, P; Ramesh, G; Khan, M S; Saikia, P; Pradhan, S

2017-01-01

Graphite plasma facing components (PFCs) were installed inside the SST-1 vacuum vessel. Prior to installation, all the graphite tiles were baked at 1000 °C in a vacuum furnace operated below 1.0 × 10 -5 mbar. However due to the porous structure of graphite, they absorb a significant amount of water vapour from air during the installation process. Rapid desorption of this water vapour requires high temperature bake-out of the PFCs at ≥ 250 °C. In SST-1 the PFCs were baked at 250 °C using hot nitrogen gas facility to remove the absorbed water vapour. Also device with large graphite surface area has the disadvantage that a large quantity of hydrogen gets trapped inside it during plasma discharges which makes density control difficult. Helium glow discharge cleaning (He-GDC) effectively removes this stored hydrogen as well as other impurities like oxygen and hydrocarbon within few nano-meters from the surface by particle induced desorption. Before plasma operation in SST-1 tokamak, both baking of PFCs and He-GDC were carried out so that these impurities were removed effectively. The mean desorption yield of hydrogen was found to be 0.24. In this paper the results of baking and He-GDC experiments of SST-1 will be presented in detail. (paper)

Recrystallization behaviour and electrical properties of germanium ion implanted polycrystalline silicon films

International Nuclear Information System (INIS)

Kang, Myeon-Koo; Matsui, Takayuki; Kuwano, Hiroshi

1996-01-01

The recrystallization behaviour of undoped and phosphorus-doped polycrystalline silicon films amorphized by germanium ion implantation at doses ranging from 1 x 10 15 to 1 x 10 16 cm -2 are investigated, and the electrical properties of phosphorus-doped films after recrystallization are studied. The phosphorus doping concentration ranges from 3 x 10 18 to 1 x 10 20 cm -3 . It is found that the nucleation rate decreases for undoped films and increases for phosphorus-doped films with increasing germanium dose; the growth rates decrease for both doped and undoped films. The decrease in nucleation rate is caused by the increase in implantation damage. The decrease in growth rate is considered to be due to the increase in lattice strain. The grain size increases with germanium dose for undoped films, but decreases for phosphorus-doped films. The dependence of the electrical properties of the recrystallized films as a function of phosphorus doping concentration with different germanium doses can be explained in terms of the grain size, crystallinity and grain boundary barrier height. (Author)

Development of neutron-transmutation-doped germanium bolometer material

International Nuclear Information System (INIS)

Palaio, N.P.

1983-08-01

The behavior of lattice defects generated as a result of the neutron-transmutation-doping of germanium was studied as a function of annealing conditions using deep level transient spectroscopy (DLTS) and mobility measurements. DLTS and variable temperature Hall effect were also used to measure the activation of dopant impurities formed during the transmutation process. In additioon, a semi-automated method of attaching wires on to small chips of germanium ( 3 ) for the fabrication of infrared detecting bolometers was developed. Finally, several different types of junction field effect transistors were tested for noise at room and low temperature (approx. 80 K) in order to find the optimum device available for first stage electronics in the bolometer signal amplification circuit

Organotrichlorogermane synthesis by the reaction of elemental germanium, tetrachlorogermane and organic chloride via dichlorogermylene intermediate.

Science.gov (United States)

Okamoto, Masaki; Asano, Takuya; Suzuki, Eiichi

2004-08-07

Organotrichlorogermanes were synthesized by the reaction of elemental germanium, tetrachlorogermane and organic chlorides, methyl, propyl, isopropyl and allyl chlorides. Dichlorogermylene formed by the reaction of elemental germanium with tetrachlorogermane was the reaction intermediate, which was inserted into the carbon-chlorine bond of the organic chloride to give organotrichlorogermane. When isopropyl or allyl chloride was used as an organic chloride, organotrichlorogermane was formed also in the absence of tetrachlorogermane. These chlorides were converted to hydrogen chloride, which subsequently reacted with elemental germanium to give the dichlorogermylene intermediate. The reaction of elemental germanium, tetrachlorogermane and organic chlorides provides a simple and easy method for synthesizing organotrichlorogermanes, and all the raw materials are easily available.

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

HEROICA: A fast screening facility for the characterization of germanium detectors

Energy Technology Data Exchange (ETDEWEB)

Andreotti, Erica [Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen (Germany); Collaboration: GERDA Collaboration

2013-08-08

In the course of 2012, a facility for the fast screening of germanium detectors called HEROICA (Hades Experimental Research Of Intrinsic Crystal Appliances) has been installed at the HADES underground laboratory in the premises of the Belgian Nuclear Research Centre SCK•CEN, in Mol (Belgium). The facility allows performing a complete characterization of the critical germanium detectors' operational parameters with a rate of about two detectors per week.

Observed transitions in n = 2 ground configurations of copper, nickel, iron, chromium and germanium in tokamak discharges

International Nuclear Information System (INIS)

Hinnov, E.; Suckewer, S.; Cohen, S.; Sato, K.

1981-11-01

A number of spectrum lines of highly ionized copper, nickel, iron, chromium, and germanium have been observed and the corresponding transitions identified. The element under study is introduced into the discharge of the PLT Tokamak by means of rapid ablation by a laser pulse. The ionization state is generally distinguishable from the time behavior of the emitted light. New identifications of transitions are based on predicted wavelengths (from isoelectronic extrapolation and other data) and on approximate expected intensities. All the transitions pertain to the ground configurations of the respective ions, which are the only states strongly populated at tokamak plasma conditions. These lines are expected to be useful for spectroscopic plasma diagnostics in the 1-3 keV temperature range, and they provide direct measurement of intersystem energy separations from chromium through copper in the oxygen, nitrogen, and carbon isoelectronic sequences

Studies on fundamental technologies for producing tokamak-plasma

International Nuclear Information System (INIS)

Matsuzaki, Yoshimi

1987-10-01

The report describes studies on fundamental technologies to produce tokamak-plasma of the JFT-2 and JFT-2M tokamaks. (1) In order to measure the particle number of residual gases, calibration methods of vacuum gauges have been developed. (2) Devices for a Taylor-type discharge cleaning (TDC), a glow discharge cleaning (GDC) and ECR discharge cleaning (ECR-DC) have been made and the cleaning effects have been investigated. In TDC the most effective plasma for cleaning is obtained in the plasma with 5 eV of electron temperature. GDC is effective in removing carbon impurities, but is less effective for removing oxygen impurities. ECR-DC has nearly the similar effect as TDC. The cleaning effect of these three types were studied by comparing the properties of resulting tokamak plasmas in the JFT-2M tokamak. (3) Experimental studies of pre-ionization showed as following results; A simple pre-ionization equipment as a hot-electron-gun and a J x B gun was effective in reducing breakdown voltage. An ordinary mode wave of the electron cyclotron frequency was very effective for pre-ionization. The RF power whose density is 3.6 x 10 -2 W/cm 3 produced plasma of an electron density of 5 x 10 11 cm -3 . In this case, it is possible to start up with negligible consumption of the magnetic flux caused by the plasma resistance. (4) Concerning to studies on plasma control, the following results were obtained; In order to obtain constant plasma current, a pulse forming network was constructed and sufficient constant plasma current was achieved. In applying an iso-flux method for measuring the plasma position, it is no problem practically to use only one loop-coil and one magnetic probe. (author)

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.

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

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.

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.

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

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

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.

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

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

Discharge cleaning for a tokamak

International Nuclear Information System (INIS)

Ishii, Shigeyuki

1983-01-01

Various methods of discharge cleaning for tokamaks are described. The material of the first walls of tokamaks is usually stainless steel, inconel, titanium and so on. Hydrogen is exclusively used as the discharge gas. Glow discharge cleaning (GDC), Taylor discharge cleaning (TDC), and electron cyclotron resonance discharge cleaning (ECR-DC) are discussed in this paper. The cleaning by GDC is made by moving a movable anode to the center of a tokamak vassel. Taylor found the good cleaning effect of induced discharge by high pressure and low power discharge. This is called TDC. When the frequency of high frequency discharge in a magnetic field is equal to that of the electron cyclotron resonance, the break down potential is lowered if the pressure is sufficiently low. The ECR-CD is made by using this effect. In TDC and ECR-DC, the electron temperature, which has a close relation to the production rate of H 0 , can be controlled by the pressure. In GDC, the operating pressure was improved by the radio frequency glow (RG) method. However, there is still the danger of arcing. In case of GDC and ECR-DC, the position of plasma can be controlled, but not in case of TDC. The TDC is accepted by most of takamak devices in the world. (Kato, T.)

Cosmogenic activation of germanium used for tonne-scale rare event search experiments

Science.gov (United States)

Wei, W.-Z.; Mei, D.-M.; Zhang, C.

2017-11-01

We report a comprehensive study of cosmogenic activation of germanium used for tonne-scale rare event search experiments. The germanium exposure to cosmic rays on the Earth's surface are simulated with and without a shielding container using Geant4 for a given cosmic muon, neutron, and proton energy spectrum. The production rates of various radioactive isotopes are obtained for different sources separately. We find that fast neutron induced interactions dominate the production rate of cosmogenic activation. Geant4-based simulation results are compared with the calculation of ACTIVIA and the available experimental data. A reasonable agreement between Geant4 simulations and several experimental data sets is presented. We predict that cosmogenic activation of germanium can set limits to the sensitivity of the next generation of tonne-scale experiments.

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)

Crystal Orientation Effect on the Subsurface Deformation of Monocrystalline Germanium in Nanometric Cutting.

Science.gov (United States)

Lai, Min; Zhang, Xiaodong; Fang, Fengzhou

2017-12-01

Molecular dynamics simulations of nanometric cutting on monocrystalline germanium are conducted to investigate the subsurface deformation during and after nanometric cutting. The continuous random network model of amorphous germanium is established by molecular dynamics simulation, and its characteristic parameters are extracted to compare with those of the machined deformed layer. The coordination number distribution and radial distribution function (RDF) show that the machined surface presents the similar amorphous state. The anisotropic subsurface deformation is studied by nanometric cutting on the (010), (101), and (111) crystal planes of germanium, respectively. The deformed structures are prone to extend along the 110 slip system, which leads to the difference in the shape and thickness of the deformed layer on various directions and crystal planes. On machined surface, the greater thickness of subsurface deformed layer induces the greater surface recovery height. In order to get the critical thickness limit of deformed layer on machined surface of germanium, the optimized cutting direction on each crystal plane is suggested according to the relevance of the nanometric cutting to the nanoindentation.

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.

Dazai super-large uranium-bearing germanium deposit in western Yunnan region metallogenic geological conditions and prospect

International Nuclear Information System (INIS)

Han Yanrong; Yuan Qingbang; Li Yonghua; Zhang Ling; Dai Jiemin

1995-05-01

The Dazai super-large uranium-bearing germanium deposit is located in Bangmai Fault Basin, Western Yunnan, China. The basin basement is migmatitic granite and the cover is miocene coal-bearing clastics, Bangmai Formation. The basin development had undergone faulted rhombus basin forming, synsedimentary structure-developing and up-lifted-denuded stages. Synsedimentary faults had controlled distribution of sedimentary formation and lithofacies, and uranium and germanium mineralization. Germanium ore-bodies occur mainly in master lignite-bed of lower rhythmite. Hosted germanium-lignite is taken as main ore-type. Germanium occurs in vitrinite of lignite in the form of metal-organic complex. The metallogenetic geological conditions of the deposit are that ground preparation is uplift zone-migmatitic granite-fault basin-geothermal anomaly area, rich and thick ore-body is controlled by synsedimentary fault, peat-bog phase is favorable to accumulation for ore-forming elements, and unconformity between overlying cover and underlying basement is a channel-way of mineralizing fluid. A multiperiodic composite, being regarded sedimentation and diagenesis as a major process, uranium and germanium ore deposit has been formed through two mineralization. Four prospecting areas have been forecasted and two deposits have been accordingly discovered again. Technical-economic provableness shows that the deposit is characterized by shallow-buried, rich grade, large scale, easy mining and smelting. (9 figs.)

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

Performance of a 6x6 segmented germanium detector for {gamma}-ray tracking

Energy Technology Data Exchange (ETDEWEB)

Valiente-Dobon, J.J. E-mail: j.valiente-dobon@surrey.ac.uk; Pearson, C.J.; Regan, P.H.; Sellin, P.J.; Gelletly, W.; Morton, E.; Boston, A.; Descovich, M.; Nolan, P.J.; Simpson, J.; Lazarus, I.; Warner, D

2003-06-01

A 36 fold segmented germanium coaxial detector has been supplied by EURISYS MESURES. The outer contact is segmented both radially and longitudinally. The signals from the fast preamplifiers have been digitised by 12 bit, 40 MHz ADCs. In this article we report preliminary results obtained using this detector and their relevance for future germanium {gamma}-ray tracking arrays.

Study of the possibility of growing germanium single crystals under low temperature gradients

Science.gov (United States)

Moskovskih, V. A.; Kasimkin, P. V.; Shlegel, V. N.; Vasiliev, Y. V.; Gridchin, V. A.; Podkopaev, O. I.; Zhdankov, V. N.

2014-03-01

The possibility of growing germanium single crystals under low temperature gradients in order to produce a dislocation-free material has been studied. Germanium crystals with a dislocation density of about 100-200 cm-2 have been grown in a system with a weight control of crystal growth at maximum axial gradients of about 1.5 K/cm.

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.

dc glow-discharge cleaning for accelerator

International Nuclear Information System (INIS)

Chou, T.S.; Hseuh, H.C.

1982-01-01

Average pressure of 1 x 10 -11 torr and vacuum stability are necessary for the successful operation of the proton storage rings such as ISABELLE. Vacuum degassing at high temperature and in situ bake-out will reduce the thermoout-gassing rate of the beam tubes to approx. 10 -13 Tl/cm 2 sec, therefore achieving the required static pressure. The vacuum instability caused by beam-induced ion desorption can be solved by dc glow discharge cleaning. With evidence from this study, the present understanding of glow discharge in a cylindrically symmetric geometry is reviewed. Argon and argon/oxygen mixture serve as plasmas in the glow. The role of oxygen in cleaning the beam tubes during the glow discharge is demonstrated experimentally. Glow discharge cleaning with and without bake-out is also studied

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.)

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

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 ...

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.

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.

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

Dry Phosphorus silicate glass etching and surface conditioning and cleaning for multi-crystalline silicon solar cell processing

International Nuclear Information System (INIS)

Kagilik, Ahmed S.

2014-01-01

As an alternative to the wet chemical etching method, dry chemical etching processes for Phosphorus silicate glass [PSG} layer removal using Trifluormethane/Sulfur Hexafluoride (CHF 3 / SF 6 ) gas mixture in commercial silicon-nitride plasma enhanced chemical vapour deposition (SiN-PECVD) system is applied. The dependence of the solar cell performance on the etching temperature is investigated and optimized. It is found that the SiN-PECVD system temperature variation has a significant impact on the whole solar cell characteristics. A dry plasma cleaning treatment of the Si wafer surface after the PSG removal step is also investigated and developed. The cleaning step is used to remove the polymer film which is formed during the PSG etching using both oxygen and hydrogen gases. By applying an additional cleaning step, the polymer film deposited on the silicon wafer surface after PSG etching is eliminated. The effect of different plasma cleaning conditions on solar cell performance is investigated. After optimization of the plasma operating conditions, the performance of the solar cell is improved and the overall gain in efficiency of 0.6% absolute is yielded compared to a cell without any further cleaning step. On the other hand, the best solar cell characteristics can reach values close to that achieved by the conventional wet chemical etching processes demonstrating the effectiveness of the additional O 2 /H 2 post cleaning treatment.(author)

Atomic ionization of germanium by neutrinos from an ab initio approach

International Nuclear Information System (INIS)

Chen, Jiunn-Wei; Chi, Hsin-Chang; Huang, Keh-Ning; Liu, C.-P.; Shiao, Hao-Tse; Singh, Lakhwinder; Wong, Henry T.; Wu, Chih-Liang; Wu, Chih-Pan

2014-01-01

An ab initio calculation of atomic ionization of germanium by neutrinos was carried out in the framework of multiconfiguration relativistic random phase approximation and benchmarked by related atomic structure and photoabsorption data. This improves over the conventional approach based on scattering off free electrons whose validity at sub-keV energy transfer is questionable. Limits on neutrino magnetic moments are derived using reactor neutrino data taken with low threshold germanium detectors. Future applications of these atomic techniques will greatly reduce the atomic uncertainties in low-energy neutrino and dark matter detections.

Nature of oxygen donors and radiation defects in oxygen-doped germanium

International Nuclear Information System (INIS)

Fukuoka, Noboru; Atobe, Kozo; Honda, Makoto; Matsuda, Koji.

1991-01-01

The nature of oxygen donors and radiation defects in oxygen-doped germanium were studied through measurements of the infrared absorption spectrum, deep level transient spectroscopy spectrum and carrier concentration. It is revealed that a new donor is not formed in oxygen-doped germanium. An A-center (interstitial oxygen-vacancy pair) forms a complex with a thermal donor in its annealing stage at 60degC-140degC. The introduction rate of defects by 1.5 MeV electron irradiation was enhanced in thermal-donor-doped samples. (author)

Buried melting in germanium implanted silicon by millisecond flash lamp annealing

International Nuclear Information System (INIS)

Voelskow, Matthias; Yankov, Rossen; Skorupa, Wolfgang; Pezoldt, Joerg; Kups, Thomas

2008-01-01

Flash lamp annealing in the millisecond range has been used to induce buried melting in silicon. For this purpose high dose high-energy germanium implantation has been employed to lower the melting temperature of silicon in a predetermined depth region. Subsequent flash lamp treatment at high energy densities leads to local melting of the germanium rich layer. The thickness of the molten layer has been found to depend on the irradiation energy density. During the cool-down period, epitaxial crystallization takes place resulting in a largely defect-free layer

Long-term radiation damage to a spaceborne germanium spectrometer

CERN Document Server

Kurczynski, P; Hull, E L; Palmer, D; Harris, M J; Seifert, H; Teegarden, B J; Gehrels, N; Cline, T L; Ramaty, R; Sheppard, D; Madden, N W; Luke, P N; Cork, C P; Landis, D A; Malone, D F; Hurley, K

1999-01-01

The Transient Gamma-Ray Spectrometer aboard the Wind spacecraft in deep space has observed gamma-ray bursts and solar events for four years. The germanium detector in the instrument has gradually deteriorated from exposure to the approx 10 sup 8 p/cm sup 2 /yr(>100 MeV) cosmic-ray flux. Low-energy tailing and loss of efficiency, attributed to hole trapping and conversion of the germanium from n- to p-type as a result of crystal damage, were observed. Raising the detector bias voltage ameliorated both difficulties and restored the spectrometer to working operation. Together, these observations extend our understanding of the effects of radiation damage to include the previously unsuccessfully studied regime of long-term operation in space. (author)

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.

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.

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.

Strong quantum-confined stark effect in germanium quantum-well structures on silicon

International Nuclear Information System (INIS)

Kuo, Y.; Lee, Y. K.; Gei, Y.; Ren, S; Roth, J. E.; Miller, D. A.; Harris, J. S.

2006-01-01

Silicon is the dominant semiconductor for electronics, but there is now a growing need to integrate such component with optoelectronics for telecommunications and computer interconnections. Silicon-based optical modulators have recently been successfully demonstrated but because the light modulation mechanisms in silicon are relatively weak, long (for example, several millimeters) devices or sophisticated high-quality-factor resonators have been necessary. Thin quantum-well structures made from III-V semiconductors such as GaAs, InP and their alloys exhibit the much stronger Quantum-Confined Stark Effect (QCSE) mechanism, which allows modulator structures with only micrometers of optical path length. Such III-V materials are unfortunately difficult to integrate with silicon electronic devices. Germanium is routinely integrated with silicon in electronics, but previous silicon-germanium structures have also not shown strong modulation effects. Here we report the discovery of the QCSE, at room temperature, in thin germanium quantum-well structures grown on silicon. The QCSE here has strengths comparable to that in III-V materials. Its clarity and strength are particularly surprising because germanium is an indirect gap semiconductor, such semiconductors often display much weak optical effects than direct gap materials (such as the III-V materials typically used for optoelectronics). This discovery is very promising for small, high-speed, low-power optical output devices fully compatible with silicon electronics manufacture. (author)

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

Methods to improve and understand the sensitivity of high purity germanium detectors for searches of rare events

International Nuclear Information System (INIS)

Volynets, Oleksandr

2012-01-01

Observation of neutrinoless double beta-decay could answer fundamental questions on the nature of neutrinos. High purity germanium detectors are well suited to search for this rare process in germanium. Successful operation of such experiments requires a good understanding of the detectors and the sources of background. Possible background sources not considered before in the presently running GERDA high purity germanium detector experiment were studied. Pulse shape analysis using artificial neural networks was used to distinguish between signal-like and background-like events. Pulse shape simulation was used to investigate systematic effects influencing the efficiency of the method. Possibilities to localize the origin of unwanted radiation using Compton back-tracking in a granular detector system were examined. Systematic effects in high purity germanium detectors influencing their performance have been further investigated using segmented detectors. The behavior of the detector response at different operational temperatures was studied. The anisotropy effects due to the crystallographic structure of germanium were facilitated in a novel way to determine the orientation of the crystallographic axes.

Methods to improve and understand the sensitivity of high purity germanium detectors for searches of rare events

Energy Technology Data Exchange (ETDEWEB)

Volynets, Oleksandr

2012-07-27

Observation of neutrinoless double beta-decay could answer fundamental questions on the nature of neutrinos. High purity germanium detectors are well suited to search for this rare process in germanium. Successful operation of such experiments requires a good understanding of the detectors and the sources of background. Possible background sources not considered before in the presently running GERDA high purity germanium detector experiment were studied. Pulse shape analysis using artificial neural networks was used to distinguish between signal-like and background-like events. Pulse shape simulation was used to investigate systematic effects influencing the efficiency of the method. Possibilities to localize the origin of unwanted radiation using Compton back-tracking in a granular detector system were examined. Systematic effects in high purity germanium detectors influencing their performance have been further investigated using segmented detectors. The behavior of the detector response at different operational temperatures was studied. The anisotropy effects due to the crystallographic structure of germanium were facilitated in a novel way to determine the orientation of the crystallographic axes.

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.

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.

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.

Laser cleaning of diagnostic mirrors from tokamak-like carbon contaminants

Energy Technology Data Exchange (ETDEWEB)

Maffini, A., E-mail: alessandro.maffini@polimi.it [Dipartimento di Energia, Politecnico di Milano, Milan (Italy); Uccello, A. [Dipartimento di Energia, Politecnico di Milano, Milan (Italy); Dellasega, D. [Dipartimento di Energia, Politecnico di Milano, Milan (Italy); Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, EURATOM-ENEA-CNR Association, Milan (Italy); Russo, V. [Dipartimento di Energia, Politecnico di Milano, Milan (Italy); Perissinotto, S. [Center for Nano Science and Technology @ Polimi, Istituto Italiano di Tecnologia, Milan (Italy); Passoni, M. [Dipartimento di Energia, Politecnico di Milano, Milan (Italy); Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, EURATOM-ENEA-CNR Association, Milan (Italy)

2015-08-15

This paper presents a laboratory-scale experimental investigation of laser cleaning of diagnostic First Mirrors (FMs). Redeposition of contaminants sputtered from tokamak first wall onto FMs surface could dramatically decrease their reflectivity in an unacceptable way for the functioning of the plasma diagnostic systems. Laser cleaning is a promising solution to tackle this issue. In this work, pulsed laser deposition was exploited to produce rhodium films functional as FMs and to deposit onto them carbon contaminants with tailored features, resembling those found in tokamaks. The same laser system was also used to perform laser cleaning experiments by means of a sample handling procedure that allows to clean some cm{sup 2} in few minutes. The cleaning effectiveness was evaluated in terms of specular reflectivity recovery and mirror surface integrity. The effect of different laser wavelengths (λ = 1064, 266 nm) on the cleaning process is also addressed.

The GALATEA test facility and a first study of α-induced surface events in a germanium detector

Energy Technology Data Exchange (ETDEWEB)

Irlbeck, Sabine

2014-01-30

Germanium detectors are a choice technology in fundamental research. They are suitable for the search for rare events due to their high sensitivity and excellent energy resolution. As an example, the GERDA (GERmanium Detector Array) experiment searching for neutrinoless double beta decay is described. The observation of this decay would resolve the fundamental question whether the neutrino is its own antiparticle. Especially adapted detector technologies and low background rates needed to detect very rare events such as neutrinoless double beta decays are discussed. The identification of backgrounds originating from the interaction of radiation, especially α-particles, is a focus of this thesis. Low background experiments face problems from α-particles due to unavoidable surface contaminations of the germanium detectors. The segmentation of detectors is used to obtain information about the special characteristics of selected events. The high precision test stand GALATEA was especially designed for surface scans of germanium detectors. As part of this work, GALATEA was completed and commissioned. The final commissioning required major upgrades of the original design which are described in detail. Collimator studies with two commercial germanium detectors are presented. Different collimation levels for a β-source were investigated and crystal axis effects were examined. The first scan with an α-source of the passivated end-plate of a special 19-fold segmented prototype detector mounted in GALATEA is described. The α-induced surface events were studied and characterized. Crosstalk and mirror pulses seen in the segments of the germanium detector were analyzed. The detector studies presented in this thesis will help to further improve the design of germanium detectors for low background experiments.

The GALATEA test facility and a first study of α-induced surface events in a germanium detector

International Nuclear Information System (INIS)

Irlbeck, Sabine

2014-01-01

Germanium detectors are a choice technology in fundamental research. They are suitable for the search for rare events due to their high sensitivity and excellent energy resolution. As an example, the GERDA (GERmanium Detector Array) experiment searching for neutrinoless double beta decay is described. The observation of this decay would resolve the fundamental question whether the neutrino is its own antiparticle. Especially adapted detector technologies and low background rates needed to detect very rare events such as neutrinoless double beta decays are discussed. The identification of backgrounds originating from the interaction of radiation, especially α-particles, is a focus of this thesis. Low background experiments face problems from α-particles due to unavoidable surface contaminations of the germanium detectors. The segmentation of detectors is used to obtain information about the special characteristics of selected events. The high precision test stand GALATEA was especially designed for surface scans of germanium detectors. As part of this work, GALATEA was completed and commissioned. The final commissioning required major upgrades of the original design which are described in detail. Collimator studies with two commercial germanium detectors are presented. Different collimation levels for a β-source were investigated and crystal axis effects were examined. The first scan with an α-source of the passivated end-plate of a special 19-fold segmented prototype detector mounted in GALATEA is described. The α-induced surface events were studied and characterized. Crosstalk and mirror pulses seen in the segments of the germanium detector were analyzed. The detector studies presented in this thesis will help to further improve the design of germanium detectors for low background experiments.

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

Pulse discharge cleaning of the vacuum vessel of HL-1 tokamak

International Nuclear Information System (INIS)

Li Guodong; Zhu Yukun; Xiao Zhenggui; Sun Shouqi; Ze Mingrui

1986-01-01

The HL-1 Tokamak was test-operated on September 21, 1984. During the period of vacuum conditioning, including 60 hours of baking up to 200 deg C and 7 x 10 4 shots of pulse discharge cleaning, the calculated quantities of carbon and oxygen removed are equivalent to 24 and 6 monolayers, respectively. Then, 124 shots of tokamak discharge were performed with low level plasma parameters. The plasma current and pulse length achieved were 60 kA and 85 ms at the toroidal magnetic field of 15 kG. This paper described the techniques used and the effect on discharge characteristics of bakeout and pulse discharge cleaning of the vacuum vessel

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

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) ...

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

Alternative, Green Processes for the Precision Cleaning of Aerospace Hardware

Science.gov (United States)

Maloney, Phillip R.; Grandelli, Heather Eilenfield; Devor, Robert; Hintze, Paul E.; Loftin, Kathleen B.; Tomlin, Douglas J.

2014-01-01

Precision cleaning is necessary to ensure the proper functioning of aerospace hardware, particularly those systems that come in contact with liquid oxygen or hypergolic fuels. Components that have not been cleaned to the appropriate levels may experience problems ranging from impaired performance to catastrophic failure. Traditionally, this has been achieved using various halogenated solvents. However, as information on the toxicological and/or environmental impacts of each came to light, they were subsequently regulated out of use. The solvent currently used in Kennedy Space Center (KSC) precision cleaning operations is Vertrel MCA. Environmental sampling at KSC indicates that continued use of this or similar solvents may lead to high remediation costs that must be borne by the Program for years to come. In response to this problem, the Green Solvents Project seeks to develop state-of-the-art, green technologies designed to meet KSCs precision cleaning needs.Initially, 23 solvents were identified as potential replacements for the current Vertrel MCA-based process. Highly halogenated solvents were deliberately omitted since historical precedents indicate that as the long-term consequences of these solvents become known, they will eventually be regulated out of practical use, often with significant financial burdens for the user. Three solvent-less cleaning processes (plasma, supercritical carbon dioxide, and carbon dioxide snow) were also chosen since they produce essentially no waste stream. Next, experimental and analytical procedures were developed to compare the relative effectiveness of these solvents and technologies to the current KSC standard of Vertrel MCA. Individually numbered Swagelok fittings were used to represent the hardware in the cleaning process. First, the fittings were cleaned using Vertrel MCA in order to determine their true cleaned mass. Next, the fittings were dipped into stock solutions of five commonly encountered contaminants and were

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...

Chip cleaning and regeneration for electrochemical sensor arrays

Energy Technology Data Exchange (ETDEWEB)

Bhalla, Vijayender [Biochemistry Department ' G.Moruzzi' , University of Bologna, Via Irnerio 48, 40126 Bologna (Italy); Carrara, Sandro, E-mail: sandro.carrara@epfl.c [Biochemistry Department ' G.Moruzzi' , University of Bologna, Via Irnerio 48, 40126 Bologna (Italy); Stagni, Claudio [Department DEIS, University of Bologna, viale Risorgimento 2, 40136 Bologna (Italy); Samori, Bruno [Biochemistry Department ' G.Moruzzi' , University of Bologna, Via Irnerio 48, 40126 Bologna (Italy)

2010-04-02

Sensing systems based on electrochemical detection have generated great interest because electronic readout may replace conventional optical readout in microarray. Moreover, they offer the possibility to avoid labelling for target molecules. A typical electrochemical array consists of many sensing sites. An ideal micro-fabricated sensor-chip should have the same measured values for all the equivalent sensing sites (or spots). To achieve high reliability in electrochemical measurements, high quality in functionalization of the electrodes surface is essential. Molecular probes are often immobilized by using alkanethiols onto gold electrodes. Applying effective cleaning methods on the chip is a fundamental requirement for the formation of densely-packed and stable self-assembly monolayers. However, the available well-known techniques for chip cleaning may not be so reliable. Furthermore, it could be necessary to recycle the chip for reuse. Also in this case, an effective recycling technique is required to re-obtain well cleaned sensing surfaces on the chip. This paper presents experimental results on the efficacy and efficiency of the available techniques for initial cleaning and further recycling of micro-fabricated chips. Piranha, plasma, reductive and oxidative cleaning methods were applied and the obtained results were critically compared. Some interesting results were attained by using commonly considered cleaning methodologies. This study outlines oxidative electrochemical cleaning and recycling as the more efficient cleaning procedure for electrochemical based sensor arrays.

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...

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.

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.

X-ray radiometric analysis of lead and zinc concentrates using germanium radiation detector

International Nuclear Information System (INIS)

Vajgachev, A.A.; Mamysh, V.A.; Mil'chakov, V.I.; Shchekin, K.I.; Berezkin, V.V.

1975-01-01

The results of determination of lead, zinc and iron in lead and zinc concentrates by the X-ray-radiometric method with the use of germanium semiconductor detector are presented. In the experiments the 57 Co source and tritium-zirconium target were used. The activity of 57 Co was 2 mc. The area of the germanium detector employed was 5g mm 2 , its thickness - 2.3 mm. In lead concentrates zinc and iron were determined from the direct intensity of K-series radiation. In the analysis of zinc concentrates the same conditions of recording and excitation were used as in the case of lead concentrates, but the measurements were conducted in saturated layers. It is demonstrated that the use of germanium semiconductor detectors in combination with the suggested methods of measurements makes it possible to perform determination of iron, zinc and lead in zinc and lead concentrates with permissible error

Two-Dimensional Spatial Imaging of Charge Transport in Germanium Crystals at Cryogenic Temperatures

Energy Technology Data Exchange (ETDEWEB)

Moffatt, Robert [Stanford Univ., CA (United States)

2016-03-01

In this dissertation, I describe a novel apparatus for studying the transport of charge in semiconductors at cryogenic temperatures. The motivation to conduct this experiment originated from an asymmetry observed between the behavior of electrons and holes in the germanium detector crystals used by the Cryogenic Dark Matter Search (CDMS). This asymmetry is a consequence of the anisotropic propagation of electrons in germanium at cryogenic temperatures. To better model our detectors, we incorporated this effect into our Monte Carlo simulations of charge transport. The purpose of the experiment described in this dissertation is to test those models in detail. Our measurements have allowed us to discover a shortcoming in our most recent Monte Carlo simulations of electrons in germanium. This discovery would not have been possible without the measurement of the full, two-dimensional charge distribution, which our experimental apparatus has allowed for the first time at cryogenic temperatures.

Laser cleaning of varnishes and contaminants on brass

Energy Technology Data Exchange (ETDEWEB)

Mateo, M.P.; Ctvrtnickova, T. [Universidad de A Coruna, Dpto. Ingenieria Industrial II, C/ Mendizabal s/n, 15403 Ferrol (Spain); Fernandez, E.; Ramos, J.A. [Instituto Tecnologico de Optica Color e Imagen, AIDO, Dpto. Laser, Valencia (Spain); Yanez, A. [Universidad de A Coruna, Dpto. Ingenieria Industrial II, C/ Mendizabal s/n, 15403 Ferrol (Spain); Nicolas, G. [Universidad de A Coruna, Dpto. Ingenieria Industrial II, C/ Mendizabal s/n, 15403 Ferrol (Spain)], E-mail: gines@cdf.udc.es

2009-03-01

The capability of laser ablation to perform controlled cleaning of varnishes containing contaminants and paints used by restorers in artistic objects from brass samples while keeping unaltered the finish structure is demonstrated in this work. Adequate laser energy per pulse and number of laser shots required to perform a suitable cleaning by laser ablation have been optimized. The inspection of the samples before and after the cleaning process by optical microscopy and by Fourier transform infrared spectroscopy (FTIR) technique demonstrated that the finish structure of the surface was intact while the coatings were completely eliminated. Furthermore, a laser-induced plasma spectroscopy (LIBS)-based detection system was applied during the irradiation process for the analysis of the material removal and also for its monitoring.

Laser cleaning of varnishes and contaminants on brass

International Nuclear Information System (INIS)

Mateo, M.P.; Ctvrtnickova, T.; Fernandez, E.; Ramos, J.A.; Yanez, A.; Nicolas, G.

2009-01-01

The capability of laser ablation to perform controlled cleaning of varnishes containing contaminants and paints used by restorers in artistic objects from brass samples while keeping unaltered the finish structure is demonstrated in this work. Adequate laser energy per pulse and number of laser shots required to perform a suitable cleaning by laser ablation have been optimized. The inspection of the samples before and after the cleaning process by optical microscopy and by Fourier transform infrared spectroscopy (FTIR) technique demonstrated that the finish structure of the surface was intact while the coatings were completely eliminated. Furthermore, a laser-induced plasma spectroscopy (LIBS)-based detection system was applied during the irradiation process for the analysis of the material removal and also for its monitoring

Enhanced light trapping by focused ion beam (FIB) induced self-organized nanoripples on germanium (100) surface

Science.gov (United States)

Kamaliya, Bhaveshkumar; Mote, Rakesh G.; Aslam, Mohammed; Fu, Jing

2018-03-01

In this paper, we demonstrate enhanced light trapping by self-organized nanoripples on the germanium surface. The enhanced light trapping leading to high absorption of light is confirmed by the experimental studies as well as the numerical simulations using the finite-difference time-domain method. We used gallium ion (Ga+) focused ion beam to enable the formation of the self-organized nanoripples on the germanium (100) surface. During the fabrication, the overlap of the scanning beam is varied from zero to negative value and found to influence the orientation of the nanoripples. Evolution of nanostructures with the variation of beam overlap is investigated. Parallel, perpendicular, and randomly aligned nanoripples with respect to the scanning direction are obtained via manipulation of the scanning beam overlap. 95% broadband absorptance is measured in the visible electromagnetic region for the nanorippled germanium surface. The reported light absorption enhancement can significantly improve the efficiency of germanium-silicon based photovoltaic systems.

Controlled localised melting in silicon by high dose germanium implantation and flash lamp annealing

International Nuclear Information System (INIS)

Voelskow, Matthias; Skorupa, Wolfgang; Pezoldt, Joerg; Kups, Thomas

2009-01-01

High intensity light pulse irradiation of monocrystalline silicon wafers is usually accompanied by inhomogeneous surface melting. The aim of the present work is to induce homogeneous buried melting in silicon by germanium implantation and subsequent flash lamp annealing. For this purpose high dose, high energy germanium implantation has been employed to lower the melting temperature of silicon in a predetermined depth region. Subsequent flash lamp irradiation at high energy densities leads to local melting of the germanium rich buried layer, whereby the thickness of the molten layer depends on the irradiation energy density. During the cooling down epitaxial crystallization takes place resulting in a largely defect-free layer. The combination of buried melting and dopant segregation has the potential to produce unusually buried doping profiles or to create strained silicon structures.

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...

Study of the effect of neutron and electron irradiations on the low temperature thermal conductivity of germanium and silicon; Etude de l'effet des irradiations neutronique et electronique sur la conductibilite thermique aux basses temperatures du germanium et du silicium

Energy Technology Data Exchange (ETDEWEB)

Vandevyver, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-06-15

The main results obtained from this work are the following: 1 Neutron irradiation (at 300 deg. K) produces lattice defects in germanium and silicon, and a corresponding very large lowering of the thermal conductivity is observed in the low temperature region (4-300 ). The results obtained have been explained with the help of the following hypotheses: for silicon a scattering of phonons by the stress fields produced by the defects; for germanium, a supplementary scattering of the electron phonon type. 2 Annealing treatments carried out on these materials above 373 deg. K restored the thermal conductivity over the whole temperature range of the measurements (4-300 deg. K); in the case of both germanium and silicon there were two steps in the annealing process. 3 A study of the thermal conductivity of germanium (initially P or N) after an electronic irradiation showed that the scattering of phonons could depend on the state of charge of the defects thus produced. (author) [French] Les principaux resultats obtenus au cours de ce travail sont les suivants : 1 Les irradiations neutroniques (a 300 deg. K) introduisent des defauts de reseau dans le germanium et le silicium et l'on observe correlativement pour ces materiaux, une tres importante diminution de conductibilite thermique dans le domaine des basses temperatures (4-300 deg. K). Les resultats obtenus ont pu etre interpretes en admettant principalement: pour le silicium, une diffusion des phonons par les champs de contrainte dus aux defauts; pour le germanium, une diffusion additionnelle du type electron-phonon. 2 Des recuits effectues sur ces materiaux au-dessus de 373 deg. K ont montre une restauration de la conductibilite thermique dans tout l'intervalle de temperature de mesure (4-300 deg. K) et comportant pour le germanium et le silicium, deux etapes de recuit 3 L'etude de la conductibilite thermique de germanium (initialement N ou P) apres une irradiation electronique, a montre que la diffusion des phonons

Photoluminescent polysaccharide-coated germanium(IV) oxide nanoparticles

Czech Academy of Sciences Publication Activity Database

Lobaz, Volodymyr; Rabyk, Mariia; Pánek, Jiří; Doris, E.; Nallet, F.; Štěpánek, Petr; Hrubý, Martin

2016-01-01

Roč. 294, č. 7 (2016), s. 1225-1235 ISSN 0303-402X R&D Projects: GA MŠk(CZ) 7AMB14FR027; GA ČR(CZ) GA13-08336S; GA MZd(CZ) NV15-25781A Institutional support: RVO:61389013 Keywords : germanium oxide nanoparticles * polysaccharide coating * photoluminescent label Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.723, year: 2016

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.)

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.).

New Approaches to Cleaning Liquid Radioactive Waste

Directory of Open Access Journals (Sweden)

Zabulonov, Yu.L.

2015-05-01

Full Text Available The industrial cleaning methods of liquid radioactive waste and technologically contaminated solutions, which contain heavy metals and radionuclides, are considered. It is shown that in the case when heavy metal ions exclusively exist in ionic form, the cleaning method with highest efficiency is electrodialysis. In the case when components, which must be removed, are in ionic and colloidal forms at the same time, the previous destruction of colloidal and organic matter (method of hydrodynamic cavitation, lowtemperature plasma etc is necessary. The developed «PTANK» method enables an effective purification of multicomponent metalcontaining man-made solutions, which contain additionally organic substances and complexes. Development of advanced membrane technologies, creation of complex recycling schemes and their synergistic combination will provide an opportunity to achieve deep cleaning of technologically contaminated solutions and minimize the amount of secondary wastes.

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

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.

Segmented Monolithic Germanium Detector Arrays for X-ray Absorption Spectroscopy. Final Report

International Nuclear Information System (INIS)

Hull, Ethan L.

2011-01-01

The experimental results from the Phase I effort were extremely encouraging. During Phase I PHDs Co. made the first strides toward a new detector technology that could have great impact on synchrotron x-ray absorption (XAS) measurements, and x-ray detector technology in general. Detector hardware that allowed critical demonstration measurements of our technology was designed and fabricated. This new technology allows good charge collection from many pixels on a single side of a multi-element monolithic germanium planar detector. The detector technology provides 'dot-like' collection electrodes having very low capacitance. The detector technology appears to perform as anticipated in the Phase I proposal. In particular, the 7-pixel detector studied showed remarkable properties; making it an interesting example of detector physics. The technology is enabled by the use of amorphous germanium contact technology on germanium planar detectors. Because of the scalability associated with the fabrication of these technologies at PHDs Co., we anticipate being able to supply larger detector systems at significantly lower cost than systems made in the conventional manner.

First-principles study of the diffusion mechanisms of the self-interstitial in germanium

International Nuclear Information System (INIS)

Carvalho, A; Jones, R; Janke, C; Goss, J P; Briddon, P R; Oeberg, S

2008-01-01

The self-interstitial in germanium can assume multiple configurations depending on the temperature and charge state. Here, we employ a first-principles density functional method to investigate the diffusion mechanisms of this defect. The energy barriers associated with the transformation between different structures are determined by the climbing nudged elastic band method, as a function of the charge state. The relation between the thermodynamic properties of the self-interstitial and the temperature evolution of electron radiation damage in germanium are discussed

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

Higher speed at lower cost and at low power consumption is a driving force for today's semiconductor technology. Despite a substantial effort toward achieving this goal via alternative technologies such as III-V compounds, silicon technology still dominates mainstream electronics. Progress in silicon technology will continue for some time with continual scaling of device geometry. However, there are foreseeable limits on achievable device performance, reliability and scaling for room temperature technologies. Thus, reduced temperature operation is commonly viewed as a means for continuing the progress towards higher performance. Although silicon CMOS will be the first candidate for low temperature applications, bipolar devices will be used in a hybrid fashion, as line drivers or in limited critical path elements. Silicon -germanium-base bipolar transistors look especially attractive for low-temperature bipolar applications. At low temperatures, various new physical phenomena become important in determining device behavior. Carrier freeze-out effects which are negligible at room temperature, become of crucial importance for analyzing the low temperature device characteristics. The conventional Pearson-Bardeen model of activation energy, used for calculation of carrier freeze-out, is based on an incomplete picture of the physics that takes place and hence, leads to inaccurate results at low temperatures. Plasma -induced bandgap narrowing becomes more pronounced in device characteristics at low temperatures. Even with modern numerical simulators, this effect is not well modeled or simulated. In this dissertation, improved models for such physical phenomena are presented. For accurate simulation of carrier freeze-out, the Pearson-Bardeen model has been extended to include the temperature dependence of the activation energy. The extraction of the model is based on the rigorous, first-principle theoretical calculations available in the literature. The new model is shown

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)

Lithium-Ion (de)insertion reaction of Germanium thin-film electrodes : an electrochemical and in situ XRD study

NARCIS (Netherlands)

Baggetto, L.; Notten, P.H.L.

2009-01-01

Germanium is a promising negative electrode candidate for lithium-ion thin-film batteries because of its very high theoretical storage capacity. When assuming full conversion of the material into the room-temperature equilibrium lithium saturated germanium phase, a theoretical capacity of or of

Normal processes of phonon-phonon scattering and thermal conductivity of germanium crystals with isotopic disorder

CERN Document Server

Kuleev, I G

2001-01-01

The effect of normal processes of the phonon-phonon scattering on the thermal conductivity of the germanium crystals with various isotopic disorder degrees is considered. The phonon pulse redistribution in the normal scattering processes both inside each oscillatory branch (the Simons mechanism) and between various phonon oscillatory branches (the Herring mechanism) is accounted for. The contributions of the longitudinal and cross-sectional phonons drift motion into the thermal conductivity are analyzed. It is shown that the pulse redistribution in the Herring relaxation mechanism leads to essential suppression of the longitudinal phonons drift motion in the isotopically pure germanium crystals. The calculations results of thermal conductivity for the Herring relaxation mechanism agree well with experimental data on the germanium crystals with various isotopic disorder degrees

Impurity engineering for germanium-doped Czochralski silicon wafer used for ultra large scale integrated circuit

Energy Technology Data Exchange (ETDEWEB)

Chen, Jiahe; Yang, Deren [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou (China)

2009-07-01

Internal gettering (IG) technology has been challenged by both the reduction of thermal budget during device fabrication and the enlargement of wafer diameter. Improving the properties of Czochralski (Cz) silicon wafers by intentional impurity doping, the so-called 'impurity engineering (IE)', is defined. Germanium has been found to be one of the important impurities for improving the internal gettering effect in Cz silicon wafer. In this paper, the investigations on IE involved with the conventional furnace anneal based denudation processing for germanium-doped Cz silicon wafer are reviewed. Meanwhile, the potential mechanisms of germanium effects for the IE of Cz silicon wafer are also interpreted based on the experimental facts. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Synthesis and Gas Phase Thermochemistry of Germanium-Containing Compounds

Energy Technology Data Exchange (ETDEWEB)

Classen, Nathan Robert [Iowa State Univ., Ames, IA (United States)

2002-01-01

The driving force behind much of the work in this dissertation was to gain further understanding of the unique olefin to carbene isomerization observed in the thermolysis of 1,1-dimethyl-2-methylenesilacyclobutane by finding new examples of it in other silicon and germanium compounds. This lead to the examination of a novel phenylmethylenesilacyclobut-2-ene, which did not undergo olefin to carbene rearrangement. A synthetic route to methylenegermacyclobutanes was developed, but the methylenegermacyclobutane system exhibited kinetic instability, making the study of the system difficult. In any case the germanium system decomposed through a complex mechanism which may not include olefin to carbene isomerization. However, this work lead to the study of the gas phase thermochemistry of a series of dialkylgermylene precursors in order to better understand the mechanism of the thermal decomposition of dialkylgermylenes. The resulting dialkylgermylenes were found to undergo a reversible intramolecular β C-H insertion mechanism.

LC-MS/MS determination of tranexamic acid in human plasma after phospholipid clean-up.

Science.gov (United States)

Fabresse, Nicolas; Fall, Fanta; Etting, Isabelle; Devillier, Philippe; Alvarez, Jean-Claude; Grassin-Delyle, Stanislas

2017-07-15

Tranexamic acid is a widely used antifibrinolytic drug but its pharmacology and pharmacokinetics remains poorly understood. Owing to the recent knowledge on phospholipid-induced matrix effects during human plasma analysis, our aim was to develop a liquid chromatography-mass spectrometry method for the quantitation of tranexamic acid after efficient sample clean-up. Sample preparation consisted in phospholipid removal and protein precipitation. Hydrophilic interaction liquid chromatography was used and the detection was achieved with multiple reaction monitoring. The method was validated according to the European Medicine Agency guideline in the range 1.0-1000.0μg/mL. The performance of the method was excellent with a precision in the range 1.2-3.0%, an accuracy between 88.4 and 96.6% and a coefficient of variation of the internal standard-normalized matrix factor below 6.7%. This method is suitable for the quantification of tranexamic acid in the wide range of concentrations observed during clinical studies, with all the advantages related to phospholipid removal. Copyright © 2017 Elsevier B.V. All rights reserved.

End points in discharge cleaning on TFTR [Tokamak Fusion Test Reactor

International Nuclear Information System (INIS)

Mueller, D.; Dylla, H.F.; Bell, M.G.

1989-07-01

It has been found necessary to perform a series of first-wall conditioning steps prior to successful high power plasma operation in the Tokamak Fusion Test Reactor (TFTR). This series begins with glow discharge cleaning (GDC) and is followed by pulse discharge cleaning (PDC). During machine conditioning, the production of impurities is monitored by a Residual Gas Analyzer (RGA). PDC is made in two distinct modes: Taylor discharge cleaning (TDC), where the plasma current is kept low (15--50 kA) and of short duration (50 ms) by means of a relatively high prefill pressure and aggressive PDC, where lower prefill pressure and higher toroidal field result in higher current (200--400 kA) limited by disruptions at q(a) approx 3 at approx 250 ms. At a constant repetition rate of 12 discharges/minute, the production rate of H 2 O, CO, or other impurities has been found to be an unreliable measure of progress in cleaning. However, the ability to produce aggressive PDC with substantial limiter heating, but without the production of x-rays from runaway electrons, is an indication that TDC is no longer necessary after approx 10 5 pulses. During aggressive PDC, the uncooled limiters are heated by the plasma from the bakeout temperature of 150 degree C to about 250 degree C over a period of three to eight hours. This limiter heating is important to enhance the rate at which H 2 O is removed from the graphite limiter. 14 refs., 3 figs., 1 tab

End points in discharge cleaning on TFTR (Tokamak Fusion Test Reactor)

Energy Technology Data Exchange (ETDEWEB)

Mueller, D.; Dylla, H.F.; Bell, M.G.; Blanchard, W.R.; Bush, C.E.; Gettelfinger, G.; Hawryluk, R.J.; Hill, K.W.; Janos, A.C.; Jobes, F.C.

1989-07-01

It has been found necessary to perform a series of first-wall conditioning steps prior to successful high power plasma operation in the Tokamak Fusion Test Reactor (TFTR). This series begins with glow discharge cleaning (GDC) and is followed by pulse discharge cleaning (PDC). During machine conditioning, the production of impurities is monitored by a Residual Gas Analyzer (RGA). PDC is made in two distinct modes: Taylor discharge cleaning (TDC), where the plasma current is kept low (15--50 kA) and of short duration (50 ms) by means of a relatively high prefill pressure and aggressive PDC, where lower prefill pressure and higher toroidal field result in higher current (200--400 kA) limited by disruptions at q(a) /approx/ 3 at /approx/ 250 ms. At a constant repetition rate of 12 discharges/minute, the production rate of H/sub 2/O, CO, or other impurities has been found to be an unreliable measure of progress in cleaning. However, the ability to produce aggressive PDC with substantial limiter heating, but without the production of x-rays from runaway electrons, is an indication that TDC is no longer necessary after /approx/ 10/sup 5/ pulses. During aggressive PDC, the uncooled limiters are heated by the plasma from the bakeout temperature of 150/degree/C to about 250/degree/C over a period of three to eight hours. This limiter heating is important to enhance the rate at which H/sub 2/O is removed from the graphite limiter. 14 refs., 3 figs., 1 tab.

Biallelic and Genome Wide Association Mapping of Germanium Tolerant Loci in Rice (Oryza sativa L..

Directory of Open Access Journals (Sweden)

Partha Talukdar

Full Text Available Rice plants accumulate high concentrations of silicon. Silicon has been shown to be involved in plant growth, high yield, and mitigating biotic and abiotic stresses. However, it has been demonstrated that inorganic arsenic is taken up by rice through silicon transporters under anaerobic conditions, thus the ability to efficiently take up silicon may be considered either a positive or a negative trait in rice. Germanium is an analogue of silicon that produces brown lesions in shoots and leaves, and germanium toxicity has been used to identify mutants in silicon and arsenic transport. In this study, two different genetic mapping methods were performed to determine the loci involved in germanium sensitivity in rice. Genetic mapping in the biparental cross of Bala × Azucena (an F6 population and a genome wide association (GWA study with 350 accessions from the Rice Diversity Panel 1 were conducted using 15 μM of germanic acid. This identified a number of germanium sensitive loci: some co-localised with previously identified quantitative trait loci (QTL for tissue silicon or arsenic concentration, none co-localised with Lsi1 or Lsi6, while one single nucleotide polymorphism (SNP was detected within 200 kb of Lsi2 (these are genes known to transport silicon, whose identity was discovered using germanium toxicity. However, examining candidate genes that are within the genomic region of the loci detected above reveals genes homologous to both Lsi1 and Lsi2, as well as a number of other candidate genes, which are discussed.

Geometrical and band-structure effects on phonon-limited hole mobility in rectangular cross-sectional germanium nanowires

International Nuclear Information System (INIS)

Tanaka, H.; Mori, S.; Morioka, N.; Suda, J.; Kimoto, T.

2014-01-01

We calculated the phonon-limited hole mobility in rectangular cross-sectional [001], [110], [111], and [112]-oriented germanium nanowires, and the hole transport characteristics were investigated. A tight-binding approximation was used for holes, and phonons were described by a valence force field model. Then, scattering probability of holes by phonons was calculated taking account of hole-phonon interaction atomistically, and the linearized Boltzmann's transport equation was solved to calculate the hole mobility at low longitudinal field. The dependence of the hole mobility on nanowire geometry was analyzed in terms of the valence band structure of germanium nanowires, and it was found that the dependence was qualitatively reproduced by considering an average effective mass and the density of states of holes. The calculation revealed that [110] germanium nanowires with large height along the [001] direction show high hole mobility. Germanium nanowires with this geometry are also expected to exhibit high electron mobility in our previous work, and thus they are promising for complementary metal-oxide-semiconductor (CMOS) applications

Electrochemical characterization of irreversibly adsorbed germanium on platinum stepped surfaces vicinal to Pt(1 0 0)

International Nuclear Information System (INIS)

Rodriguez, P.; Herrero, E.; Solla-Gullon, J.; Vidal-Iglesias, F.J.; Aldaz, A.; Feliu, J.M.

2005-01-01

The electrochemical behavior of germanium irreversibly adsorbed at stepped surfaces vicinal to the Pt(1 0 0) pole is reported. The process taking part on the (1 0 0) terraces is evaluated from charge density measurements and calibration lines versus the terrace dimension are plotted. On the series Pt(2n - 1,1,1) having (1 1 1) monoatomic steps, the charge involved in the redox process undergone by the irreversibly adsorbed germanium is able to account for (n - 0.5) terrace atoms, thus suggesting some steric difficulties in the growth of the adlayer on the (1 0 0) terraces. Conversely, no steric problems are apparent in the series Pt(n,1,0) in which more open (1 0 0) steps are present on the (1 0 0) terraces. In this latter case the charge density under the germanium redox peaks is proportional to the number of terrace atoms. Some comparison is made with other stepped surfaces to understand the behavior and stability of germanium irreversibly adsorbed on the different platinum surface sites

Performance of a Small Anode Germanium Well detector

International Nuclear Information System (INIS)

Adekola, A.S.; Colaresi, J.; Douwen, J.; Mueller, W.F.; Yocum, K.M.

2015-01-01

The performance of Small Anode Germanium (SAGe) Well detector [1] has been evaluated for a range of sample sizes and geometries counted inside the well, on the end cap or in Marinelli beakers. The SAGe Well is a new type of low capacitance germanium well detector manufactured using small anode technology. The detector has similar energy resolution performance to semi-planar detectors, and offers significant improvement over the Coaxial and existing Well detectors. Resolution performance of 0.75 keV Full Width at Half Maxiumum (FWHM) at 122 keV γ-ray energy and resolution of 2.0–2.3 keV FWHM at 1332 keV γ-ray energy are guaranteed. Such outstanding resolution performance will benefit environmental applications in revealing the detailed radionuclide content of samples, particularly at low energy, and will enhance the detection sensitivity resulting in reduced counting time. This paper reports the counting performance of SAGe Well detector for range of sample sizes and geometries and how it compares to other detector types

Performance of a Small Anode Germanium Well detector

Energy Technology Data Exchange (ETDEWEB)

Adekola, A.S., E-mail: aderemi.adekola@canberra.com; Colaresi, J.; Douwen, J.; Mueller, W.F.; Yocum, K.M.

2015-06-01

The performance of Small Anode Germanium (SAGe) Well detector [1] has been evaluated for a range of sample sizes and geometries counted inside the well, on the end cap or in Marinelli beakers. The SAGe Well is a new type of low capacitance germanium well detector manufactured using small anode technology. The detector has similar energy resolution performance to semi-planar detectors, and offers significant improvement over the Coaxial and existing Well detectors. Resolution performance of 0.75 keV Full Width at Half Maxiumum (FWHM) at 122 keV γ-ray energy and resolution of 2.0–2.3 keV FWHM at 1332 keV γ-ray energy are guaranteed. Such outstanding resolution performance will benefit environmental applications in revealing the detailed radionuclide content of samples, particularly at low energy, and will enhance the detection sensitivity resulting in reduced counting time. This paper reports the counting performance of SAGe Well detector for range of sample sizes and geometries and how it compares to other detector types.

Characterisation of the SmartPET planar Germanium detectors

Energy Technology Data Exchange (ETDEWEB)

Boston, H.C. [Department of Physics, University of Liverpool, Oliver Lodge Laboratory, Liverpool L69 7ZE (United Kingdom)], E-mail: H.C.Boston@liverpool.ac.uk; Boston, A.J.; Cooper, R.J.; Cresswell, J.; Grint, A.N.; Mather, A.R.; Nolan, P.J.; Scraggs, D.P.; Turk, G. [Department of Physics, University of Liverpool, Oliver Lodge Laboratory, Liverpool L69 7ZE (United Kingdom); Hall, C.J.; Lazarus, I. [CCLRC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Berry, A.; Beveridge, T.; Gillam, J.; Lewis, R. [School of Physics and Materials Engineering, Monash University, Melbourne (Australia)

2007-08-21

Small Animal Reconstruction PET (SmartPET) is a project funded by the UK medical research council (MRC) to demonstrate proof of principle that Germanium can be utilised in Positron Emission Tomography (PET). The SmartPET demonstrator consists of two orthogonal strip High Purity Germanium (HPGe) planar detectors manufactured by ORTEC. The aim of the project is to produce images of an internal source with sub mm{sup 3} spatial resolution. Before this image can be achieved the detectors have to be fully characterised to understand the response at any given location to a {gamma}-ray interaction. This has been achieved by probing the two detectors at a number of specified points with collimated sources of various energies and strengths. A 1 mm diameter collimated beam of photons was raster scanned in 1 mm steps across the detector. Digital pulse shape data were recorded from all the detector channels and the performance of the detector for energy and position determination has been assessed. Data will be presented for the first SmartPET detector.

Plasma technology directory

International Nuclear Information System (INIS)

Ward, P.P.; Dybwad, G.L.

1995-01-01

The Plasma Technology Directory has two main goals: (1) promote, coordinate, and share plasma technology experience and equipment within the Department of Energy; and (2) facilitate technology transfer to the commercial sector where appropriate. Personnel are averaged first by Laboratory and next by technology area. The technology areas are accelerators, cleaning and etching deposition, diagnostics, and modeling

The low thermal gradient CZ technique as a way of growing of dislocation-free germanium crystals

Science.gov (United States)

Moskovskih, V. A.; Kasimkin, P. V.; Shlegel, V. N.; Vasiliev, Y. V.; Gridchin, V. A.; Podkopaev, O. I.

2014-09-01

This paper considers the possibility of growth of dislocation-free germanium single crystals. This is achieved by reducing the temperature gradients at the level of 1 K/cm and lower. Single germanium crystals 45-48 mm in diameter with a dislocation density of 102 cm-2 were grown by a Low Thermal Gradient Czochralski technique (LTG CZ).

Probe measurements of hydrogen fluxes during discharge cleaning in JFT-2M

International Nuclear Information System (INIS)

Matsuzaki, Y.

1989-01-01

Thermal desorption spectroscopy (TDS) has been applied during discharge cleaning in the JFT-2M tokamak to measure hydrogen fluxes. The TDS carbon sample, thickness 0.13 mm, was heated to 1000 0 C by direct current and the temperature distribution of the sample surface measured by infrared thermography. The probe was exposed to three types of plasma: Taylor-type discharge cleaning (TDC), ECR discharge cleaning (ECR-DC), and glow discharge cleaning (GDC). The TDS spectra show peak desorption at around 800 0 C. The hydrogen flux, obtained by integration of the TDS spectrum, decreases exponentially in the radial direction with decay length 7.4 cm and 5.8 cm in TDC and ECR-DC, respectively. The relation between hydrogen fluxes and water vapour production was investigated. In TDC, the amount of water vapour depends more strongly on the electron temperature of the plasma than on the hydrogen flux. In ECR-DC, the production of water vapour increases approximately linearly with the hydrogen-flux. In GDC, hydrogen fluxes were measured by TDS but no water vapour could be detected in the residual gases during the discharge. (orig.)

Far-Infrared Magneto-Optical Studies in Germanium and Indium-Antimonide at High Intensities

Science.gov (United States)

Leung, Michael

Observations of nonlinear magneto-optical phenomena occurring in p-type Germanium and n-type Indium Antimonide are reported. These include multi-photon ionization of impurity states, and a new observation, the magneto-photon ionization of impurity states, and a new observation, the magneto-photon drag effect. A novel source of far-infrared radiation has been used. This source uses a pulsed CO(,2) LASER to optically pump a super-radiant cell, generating light with intensities up to 100 KW/cm('2) and wavelengths from 66 (mu)m to 496 (mu)m in a pulse of 150 nanoseconds duration. The Germanium samples were doped with Gallium, which is a shallow acceptor with an ionization potential of 11 meV. At liquid Helium temperature virtually all charge carriers are bound to acceptor sites. However, the high intensity radiation unexpectedly ionizes the acceptors. This is demonstrated through measurements of photoconductivity, transmission and the photo-Hall Effect. This observation is unexpected because the photon energy is one-fourth the ionization potential. Rate equations describing sequential multiphoton excitations are in agreement with the experimental results. The intermediate states are postulated to be acceptor exciton band states. Studies of the photoexcited mobility at 496 (mu)m suggest that at non-saturating levels of photoexcitation, the primary scattering mechanism of hot holes in Germanium is by neutral impurities. A new magneto-optical effect, the magneto-photon drag effect, has been studied in both Germanium and Indium Antimonide. This is simply the absorption of momentum by free carriers, from an incident photon field. It has been found that the mechanism for this effect is different in the two materials. In Germanium, the effect occurs when carriers make optical transitions from the heavy hole band to the light hole band. Thus, the magneto-optical behavior depends heavily upon the band structure. On the other hand, a modified Drude model (independent electron

Germanium microstrip detectors with 50 and 100 μm pitch

International Nuclear Information System (INIS)

Amendolia, S.R.; Bedeschi, F.; Bertolucci, E.; Bettoni, D.; Bosisio, L.; Bottigli, U.; Bradaschia, C.; Dell'Orso, M.; Fidecaro, F.; Foa, L.; Focardi, E.; Giannetti, P.; Giorgi, M.A.; Marrocchesi, P.S.; Menzione, A.; Raso, G.; Ristori, L.; Scribano, A.; Stefanini, A.; Tenchini, R.; Tonelli, G.; Triggiani, G.; Haller, E.E.; Hansen, W.L.; Luke, P.N.

1984-01-01

Multi-electrode germanium detectors are being used as an active target for decay path measurements of charmed mesons. The procedure used to fabricate such detectors is described and a brief analysis of their performance is given. (orig.)

Non-local electrical spin injection and detection in germanium at room temperature

Science.gov (United States)

Rortais, F.; Vergnaud, C.; Marty, A.; Vila, L.; Attané, J.-P.; Widiez, J.; Zucchetti, C.; Bottegoni, F.; Jaffrès, H.; George, J.-M.; Jamet, M.

2017-10-01

Non-local carrier injection/detection schemes lie at the very foundation of information manipulation in integrated systems. This paradigm consists in controlling with an external signal the channel where charge carriers flow between a "source" and a well separated "drain." The next generation electronics may operate on the spin of carriers in addition to their charge and germanium appears as the best hosting material to develop such a platform for its compatibility with mainstream silicon technology and the predicted long electron spin lifetime at room temperature. In this letter, we demonstrate injection of pure spin currents (i.e., with no associated transport of electric charges) in germanium, combined with non-local spin detection at 10 K and room temperature. For this purpose, we used a lateral spin valve with epitaxially grown magnetic tunnel junctions as spin injector and spin detector. The non-local magnetoresistance signal is clearly visible and reaches ≈15 mΩ at room temperature. The electron spin lifetime and diffusion length are 500 ps and 1 μm, respectively, the spin injection efficiency being as high as 27%. This result paves the way for the realization of full germanium spintronic devices at room temperature.

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

Position resolution simulations for the inverted-coaxial germanium detector, SIGMA

Science.gov (United States)

Wright, J. P.; Harkness-Brennan, L. J.; Boston, A. J.; Judson, D. S.; Labiche, M.; Nolan, P. J.; Page, R. D.; Pearce, F.; Radford, D. C.; Simpson, J.; Unsworth, C.

2018-06-01

The SIGMA Germanium detector has the potential to revolutionise γ-ray spectroscopy, providing superior energy and position resolving capabilities compared with current large volume state-of-the-art Germanium detectors. The theoretical position resolution of the detector as a function of γ-ray interaction position has been studied using simulated detector signals. A study of the effects of RMS noise at various energies has been presented with the position resolution ranging from 0.33 mm FWHM at Eγ = 1 MeV, to 0.41 mm at Eγ = 150 keV. An additional investigation into the effects pulse alignment have on pulse shape analysis and in turn, position resolution has been performed. The theoretical performance of SIGMA operating in an experimental setting is presented for use as a standalone detector and as part of an ancillary system.

Bond particle model for semiconductor melts and its application to liquid structure germanium

International Nuclear Information System (INIS)

Ferrante, A.; Tosi, M.P.

1988-08-01

A simple type of liquid state model is proposed to describe on a primitive level the melt of an elemental group IV semiconductor as a mixture of atoms and bond particles. The latter, on increase of a coupling strength parameter becomes increasingly localized between pairs of atoms up to local tetrahedral coordination of atoms by bond particles. Angular interatomic correlations are built into the model as bond particle localization grows, even though the bare interactions between the components of the liquid are formally described solely in terms of central pair potentials. The model is solved for liquid structure by standard integral equation techniques of liquid state theory and by Monte Carlo simulation, for values of the parameters which are appropriate to liquid germanium down to strongly supercooled states. The calculated liquid structure is compared with the results of diffraction experiments on liquid germanium near freezing and discussed in relation to diffraction data on amorphous germanium. The model suggests simple melting criteria for elemental and polar semiconductors, which are empirically verified. (author). 25 refs, 9 figs, 3 tabs

An ultralow background germanium gamma-ray spectrometer

International Nuclear Information System (INIS)

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

1984-01-01

The monitoring of minimum detectable activity is becoming increasingly important as environmental concerns and regulations require more sensitive measurement of the radioactivity levels in the workplace and the home. In measuring this activity, however, the background becomes one of the limiting factors. Anticoincidence systems utilizing both NaI(T1) and plastic scintillators have proven effective in reducing some components of the background, but radiocontaminants in the various regions of these systems have limited their effectiveness, and their cost is often prohibitive. In order to obtain a genuinely low background detector system, all components must be free of detectable radioactivity, and the cosmic ray produced contribution must be significantly reduced. Current efforts by the authors to measure the double beta decay of Germanium 76 as predicted by Grand Unified Theories have resulted in the development of a high resolution germanium diode gamma spectrometer with an exceptionally low background. This paper describes the development of this system, outlines the configuration and operation of its preamplifier, linear amplifier, analog-to-digital converter, 4096-channel analyzer, shielding consisting of lead-sandwiched plastic scintillators wrapped in cadmium foil, photomultiplier, and its pulse generator and discriminator, and then discusses how the system can be utilized to significantly reduce the background in high resolution photon spectrometers at only moderate cost

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

Laser cleaning of ITER's diagnostic mirrors

Science.gov (United States)

Skinner, C. H.; Gentile, C. A.; Doerner, R.

2012-10-01

Practical methods to clean ITER's diagnostic mirrors and restore reflectivity will be critical to ITER's plasma operations. We report on laser cleaning of single crystal molybdenum mirrors coated with either carbon or beryllium films 150 - 420 nm thick. A 1.06 μm Nd laser system provided 220 ns pulses at 8 kHz with typical power densities of 1-2 J/cm^2. The laser beam was fiber optically coupled to a scanner suitable for tokamak applications. The efficacy of mirror cleaning was assessed with a new technique that combines microscopic imaging and reflectivity measurements [1]. The method is suitable for hazardous materials such as beryllium as the mirrors remain sealed in a vacuum chamber. Excellent restoration of reflectivity for the carbon coated Mo mirrors was observed after laser scanning under vacuum conditions. For the beryllium coated mirrors restoration of reflectivity has so far been incomplete and modeling indicates that a shorter duration laser pulse is needed. No damage of the molybdenum mirror substrates was observed.[4pt][1] C.H. Skinner et al., Rev. Sci. Instrum. at press.

Density and temperature diagnostics of a Ne-like germanium plasma created by laser

International Nuclear Information System (INIS)

Berthier, E.; Bourgade, J.L.; Combis, P.; Jacquemot, S.; Le Breton, J.P.; Louis-Jacquet, M.; Naccache, D.; Nail, M.; Peyrusse, O.

1987-01-01

In the framework of X-ray laser studies, experiments on Ne-like Ge plasma have been performed by laser irradiation at λ = 1.053 μm. Amplification in lasing transitions has been observed by varying the plasma length. Theoretical calculations of excited level population allow us to determine density and temperature from line intensity ratios

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)

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

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 ...

Study of the effect of doping on the temperature stability of the optical properties of germanium single crystals

Energy Technology Data Exchange (ETDEWEB)

Podkopaev, O. I. [Joint-Stock Company “Germanium” (Russian Federation); Shimanskiy, A. F., E-mail: shimanaf@mail.ru [Siberian Federal University (Russian Federation); Kopytkova, S. A.; Filatov, R. A. [Joint-Stock Company “Germanium” (Russian Federation); Golubovskaya, N. O. [Siberian Federal University (Russian Federation)

2016-10-15

The effect of doping on the optical transmittance of germanium single crystals is studied by infrared Fourier spectroscopy. It is established that the introduction of silicon and tellurium additives into germanium doped with antimony provides a means for improving the temperature stability of the optical properties of the crystals.

Study of the effect of doping on the temperature stability of the optical properties of germanium single crystals

International Nuclear Information System (INIS)

Podkopaev, O. I.; Shimanskiy, A. F.; Kopytkova, S. A.; Filatov, R. A.; Golubovskaya, N. O.

2016-01-01

The effect of doping on the optical transmittance of germanium single crystals is studied by infrared Fourier spectroscopy. It is established that the introduction of silicon and tellurium additives into germanium doped with antimony provides a means for improving the temperature stability of the optical properties of the crystals.

Zeeman spectroscopy of Zn-H complex in germanium

International Nuclear Information System (INIS)

Prabakar, J.P.C.; Vickers, R.E.M.; Fisher, P.

1998-01-01

Full text: A divalent substitutional zinc atom in germanium complexed with an interstitial hydrogen atom gives rise to a monovalent acceptor of trigonal symmetry. The axial nature of this complex splits the four-fold degenerate states associated with substitutional point defects into two two-fold degenerate states. Zeeman spectra of the Zn-H complex have been observed for B along and crystallographic directions in the Voigt configuration using linearly polarised radiation. Spectra of the C and D lines for B ≤ 2 Tesla are essentially identical to those of these lines of group III impurities; here B is the field strength. At all fields, splitting of the excited state of the D lines is identical to that for group III acceptors in germanium. The magnetic field dependence of the D components for both E parallel B and E perpendicular B and the selection rules demand that only one of the two two-fold 1s-like energy levels is occupied at the temperatures used instead of both. The results confirm piezospectroscopic studies which demonstrated that the axes of the complexes are along the four covalent bond directions of the host

Correlating Cleaning Thoroughness with Effectiveness and Briefly Intervening to Affect Cleaning Outcomes: How Clean Is Cleaned?

Directory of Open Access Journals (Sweden)

Robert Clifford

Full Text Available The most efficient approach to monitoring and improving cleaning outcomes remains unresolved. We sought to extend the findings of a previous study by determining whether cleaning thoroughness (dye removal correlates with cleaning efficacy (absence of molecular or cultivable biomaterial and whether one brief educational intervention improves cleaning outcomes.Before-after trial.Newly built community hospital.90 minute training refresher with surface-specific performance results.Dye removal, measured by fluorescence, and biomaterial removal and acquisition, measured with culture and culture-independent PCR-based assays, were clandestinely assessed for eight consecutive months. At this midpoint, results were presented to the cleaning staff (intervention and assessments continued for another eight consecutive months.1273 surfaces were sampled before and after terminal room cleaning. In the short-term, dye removal increased from 40.3% to 50.0% (not significant. For the entire study period, dye removal also improved but not significantly. After the intervention, the number of rooms testing positive for specific pathogenic species by culturing decreased from 55.6% to 36.6% (not significant, and those testing positive by PCR fell from 80.6% to 53.7% (P = 0.016. For nonspecific biomaterial on surfaces: a removal of cultivable Gram-negatives (GN trended toward improvement (P = 0.056; b removal of any cultivable growth was unchanged but acquisition (detection of biomaterial on post-cleaned surfaces that were contaminant-free before cleaning worsened (P = 0.017; c removal of PCR-based detection of bacterial DNA improved (P = 0.046, but acquisition worsened (P = 0.003; d cleaning thoroughness and efficacy were not correlated.At this facility, a minor intervention or minimally more aggressive cleaning may reduce pathogen-specific contamination, but not without unintended consequences.

Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

International Nuclear Information System (INIS)

Hicks, Robert F.; Selwyn, Gary S.

2001-01-01

Project was to develop a low-cost, environmentally benign technology for the decontamination and decommissioning of transuranic waste. With the invention of the atmospheric-pressure plasma jet the goal was achieved. This device selectively etches heavy metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction products are captured on filters, which yields a tremendous reduction in the volume of the waste. Studies on tantalum, a surrogate material for plutonium, have shown that etch rate of 6.0 microns per minute can be achieved under mild conditions. Over the past three years, we have made numerous improvements in the design of the plasma jet. It may now be operated for hundreds of hours and not undergo any degradation in performance. Furthermore, small compact units have been developed, which are easily deployed in the field

Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

Energy Technology Data Exchange (ETDEWEB)

Robert F. Hicks; Gary S. Selwyn

2001-01-09

Project was to develop a low-cost, environmentally benign technology for the decontamination and decommissioning of transuranic waste. With the invention of the atmospheric-pressure plasma jet the goal was achieved. This device selectively etches heavy metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction products are captured on filters, which yields a tremendous reduction in the volume of the waste. Studies on tantalum, a surrogate material for plutonium, have shown that etch rate of 6.0 microns per minute can be achieved under mild conditions. Over the past three years, we have made numerous improvements in the design of the plasma jet. It may now be operated for hundreds of hours and not undergo any degradation in performance. Furthermore, small compact units have been developed, which are easily deployed in the field.

Characterization of the Tokamak Novillo in cleaning regime

International Nuclear Information System (INIS)

Lopez C, R.; Melendez L, L.; Valencia A, R.; Chavez A, E.; Colunga S, S.; Gaytan G, E.

1992-02-01

In this work the obtained results of the investigation about the experimental characterization of those low energy pulsed discharges of the Tokamak Novillo are reported. With this it is possible to fix the one operation point but appropriate of the Tokamak to condition the chamber in the smallest possible time for the cleaning discharges regime before beginning the main discharge. The characterization of the cleaning discharges in those Tokamaks is an unique process and characteristic of each device, since the good points of operation are consequence of those particularities of the design of the machine. In the case of the Tokamak Novillo, besides characterizing it a contribution is made to the cleaning discharges regime which consists on the one product of the current peak to peak of plasma by the duration of the discharge Ip t like reference parameter for the optimization of the operation of the device in the cleaning discharge regime. The maximum value of the parameter I (p) t, under different work conditions, allowed to find the good operation point to condition the discharges chamber of the Tokamak Novillo in short time and to arrive to a regime in which is not necessary the preionization for the obtaining of the cleaning discharges. (Author)

Interaction between radiation-induced defects and lithium impurity atoms in germanium

International Nuclear Information System (INIS)

Vasil'eva, E.D.; Daluda, Yu.N.; Emtsev, V.V.; Kervalishvili, P.D.; Mashovets, T.V.

1981-01-01

The effect of gamma radiation on germanium doped with lithium in the course of extraction from a melt was studied. 60 Co γ-ray irradiation with the 6.2x10 12 cm -2 x1 -1 intensity was performed at 300 K. The temperature dependences of conductivity and Hall effect was studied in the 4.2-300 K range. It was shown that using this alloying technique lithium atoms in germanium were in a ''free'' state. It was found that on irradiation the lithium atom concentration decreases as a result of production of electrically inactive complexes with participation of lithium atoms. Besides this principal process secondary ones are observed: production of radiation donor-defects with the ionization energy Esub(c) of 80 MeV and compensating acceptors

Characterization of a high-purity germanium detector for small-animal SPECT.

Science.gov (United States)

Johnson, Lindsay C; Campbell, Desmond L; Hull, Ethan L; Peterson, Todd E

2011-09-21

We present an initial evaluation of a mechanically cooled, high-purity germanium double-sided strip detector as a potential gamma camera for small-animal SPECT. It is 90 mm in diameter and 10 mm thick with two sets of 16 orthogonal strips that have a 4.5 mm width with a 5 mm pitch. We found an energy resolution of 0.96% at 140 keV, an intrinsic efficiency of 43.3% at 122 keV and a FWHM spatial resolution of approximately 1.5 mm. We demonstrated depth-of-interaction estimation capability through comparison of pinhole acquisitions with a point source on and off axes. Finally, a flood-corrected flood image exhibited a strip-level uniformity of less than 1%. This high-purity germanium offers many desirable properties for small-animal SPECT.

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

Wall conditioning of the TBR-1 Tokamak by plasma generated by microwaves

International Nuclear Information System (INIS)

Elizondo, J.I.

1986-01-01

A new system of vaccum chamber wall conditioning in the TBR-1 Tokamak, using electron cyclotron resonance plasma of hydrogen for the discharge cleaning process is presented. The construction and performance of equipments are described, and the cleaning process to otimize the conditioning efficiency by chase of plasma parameters. (author) [pt

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

Laser decontamination and cleaning of metal surfaces: modelling and experimental studies

International Nuclear Information System (INIS)

Leontyev, A.

2011-01-01

Metal surface cleaning is highly required in different fields of modern industry. Nuclear industry seeks for new methods for oxidized surface decontamination, and thermonuclear installations require the cleaning of plasma facing components from tritium-containing deposited layer. The laser ablation is proposed as an effective and safe method for metal surface cleaning and decontamination. The important factor influencing the laser heating and ablation is the in-depth distribution of laser radiation. The model of light propagation in a scattering layer on a metal substrate is developed and applied to analyse the features of light distribution. To simulate the contaminated surfaces, the stainless steel AISI 304L was oxidized by laser and in a furnace. Radioactive contamination of the oxide layer was simulated by introducing europium and/or sodium. The decontamination factor of more than 300 was demonstrated with found optimal cleaning regime. The decreasing of the corrosion resistance was found after laser cleaning. The ablation thresholds of ITER-like surfaces were measured. The cleaning productivity of 0.07 m 2 /hour.W was found. For mirror surfaces, the damage thresholds were determined to avoid damage during laser cleaning. The possibility to restore reflectivity after thin carbon layer deposition was demonstrated. The perspectives of further development of laser cleaning are discussed. (author) [fr

Two-Step Plasma Process for Cleaning Indium Bonding Bumps

Science.gov (United States)

Greer, Harold F.; Vasquez, Richard P.; Jones, Todd J.; Hoenk, Michael E.; Dickie, Matthew R.; Nikzad, Shouleh

2009-01-01

A two-step plasma process has been developed as a means of removing surface oxide layers from indium bumps used in flip-chip hybridization (bump bonding) of integrated circuits. The two-step plasma process makes it possible to remove surface indium oxide, without incurring the adverse effects of the acid etching process.

Dissolution chemistry and biocompatibility of silicon- and germanium-based semiconductors for transient electronics.

Science.gov (United States)

Kang, Seung-Kyun; Park, Gayoung; Kim, Kyungmin; Hwang, Suk-Won; Cheng, Huanyu; Shin, Jiho; Chung, Sangjin; Kim, Minjin; Yin, Lan; Lee, Jeong Chul; Lee, Kyung-Mi; Rogers, John A

2015-05-06

Semiconducting materials are central to the development of high-performance electronics that are capable of dissolving completely when immersed in aqueous solutions, groundwater, or biofluids, for applications in temporary biomedical implants, environmentally degradable sensors, and other systems. The results reported here include comprehensive studies of the dissolution by hydrolysis of polycrystalline silicon, amorphous silicon, silicon-germanium, and germanium in aqueous solutions of various pH values and temperatures. In vitro cellular toxicity evaluations demonstrate the biocompatibility of the materials and end products of dissolution, thereby supporting their potential for use in biodegradable electronics. A fully dissolvable thin-film solar cell illustrates the ability to integrate these semiconductors into functional systems.

GIOVE: a new detector setup for high sensitivity germanium spectroscopy at shallow depth

International Nuclear Information System (INIS)

Heusser, G.; Weber, M.; Hakenmüller, J.; Laubenstein, M.; Lindner, M.; Maneschg, W.; Simgen, H.; Stolzenburg, D.; Strecker, H.

2015-01-01

We report on the development and construction of the high-purity germanium spectrometer setup GIOVE (Germanium Inner Outer VEto), recently built and now operated at the shallow underground laboratory of the Max-Planck-Institut für Kernphysik, Heidelberg. Particular attention was paid to the design of a novel passive and active shield, aiming at efficient rejection of environmental and muon induced radiation backgrounds. The achieved sensitivity level of ≤100 μBq kg -1 for primordial radionuclides from U and Th in typical γ ray sample screening measurements is unique among instruments located at comparably shallow depths and can compete with instruments at far deeper underground sites

GIOVE: a new detector setup for high sensitivity germanium spectroscopy at shallow depth

Energy Technology Data Exchange (ETDEWEB)

Heusser, G., E-mail: gerd.heusser@mpi-hd.mpg.de; Weber, M., E-mail: marc.weber@mpi-hd.mpg.de; Hakenmüller, J. [Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117, Heidelberg (Germany); Laubenstein, M. [Laboratori Nazionali del Gran Sasso, Via G. Acitelli 22, 67100, Assergi, AQ (Italy); Lindner, M.; Maneschg, W.; Simgen, H.; Stolzenburg, D.; Strecker, H. [Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117, Heidelberg (Germany)

2015-11-09

We report on the development and construction of the high-purity germanium spectrometer setup GIOVE (Germanium Inner Outer VEto), recently built and now operated at the shallow underground laboratory of the Max-Planck-Institut für Kernphysik, Heidelberg. Particular attention was paid to the design of a novel passive and active shield, aiming at efficient rejection of environmental and muon induced radiation backgrounds. The achieved sensitivity level of ≤100 μBq kg{sup -1} for primordial radionuclides from U and Th in typical γ ray sample screening measurements is unique among instruments located at comparably shallow depths and can compete with instruments at far deeper underground sites.

GIOVE: a new detector setup for high sensitivity germanium spectroscopy at shallow depth

Energy Technology Data Exchange (ETDEWEB)

Heusser, G.; Weber, M.; Hakenmueller, J.; Lindner, M.; Maneschg, W.; Simgen, H.; Stolzenburg, D.; Strecker, H. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Laubenstein, M. [Laboratori Nazionali del Gran Sasso, Assergi (Italy)

2015-11-15

We report on the development and construction of the high-purity germanium spectrometer setup GIOVE (Germanium Inner Outer VEto), recently built and now operated at the shallow underground laboratory of the Max-Planck-Institut fuer Kernphysik, Heidelberg. Particular attention was paid to the design of a novel passive and active shield, aiming at efficient rejection of environmental and muon induced radiation backgrounds. The achieved sensitivity level of ≤ 100μBq kg{sup -1} for primordial radionuclides from U and Th in typical γ ray sample screening measurements is unique among instruments located at comparably shallow depths and can compete with instruments at far deeper underground sites. (orig.)

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.

CDEX-1 1 kg point-contact germanium detector for low mass dark matter searches

International Nuclear Information System (INIS)

Kang Kejun; Yue Qian; Wu Yucheng

2013-01-01

The CDEX collaboration has been established for direct detection of light dark matter particles, using ultra-low energy threshold point-contact p-type germanium detectors, in China JinPing underground Laboratory (CJPL). The first 1 kg point-contact germanium detector with a sub-keV energy threshold has been tested in a passive shielding system located in CJPL. The outputs from both the point-contact P + electrode and the outside N + electrode make it possible to scan the lower energy range of less than 1 keV and at the same time to detect the higher energy range up to 3 MeV. The outputs from both P + and N + electrode may also provide a more powerful method for signal discrimination for dark matter experiment. Some key parameters, including energy resolution, dead time, decay times of internal X-rays, and system stability, have been tested and measured. The results show that the 1 kg point-contact germanium detector, together with its shielding system and electronics, can run smoothly with good performances. This detector system will be deployed for dark matter search experiments. (authors)

The electronic and optical properties of germanium tellurite glasses containing various transition metal oxides

International Nuclear Information System (INIS)

Khan, M.N.

1988-01-01

Various transition metal oxides, such as TiO 2 , V 2 O 5 , NiO, CuO, and ZnO are added to germanium-tellurite glass and measurements are reported of the electrical conductivity, density, optical absorption, infra-red absorption spectra, and electron spin resonance. It is found that the d.c. conductivity of glasses containing the same amount of V 2 O 5 is higher than that of germanium tellurite glasses containing a similar amount of other transition metal oxides, and is due to hopping between localized states. The optical absorption measurements show that the fundamental absorption edge is a function of glass composition and the optical absorption is due to forbidden indirect transitions. From the infra-red absorption spectra, it is found that the addition of transition metal oxides does not introduce any new absorption band in the infra-red spectrum of germanium tellurite glasses. A small shift of existing absorptions toward higher wave number is observed. The ESR measurements revealed that some transition metal ions are diamagnetic while others are paramagnetic in the glass network. (author)

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

Study of the effect of neutron and electron irradiations on the low temperature thermal conductivity of germanium and silicon

International Nuclear Information System (INIS)

Vandevyver, M.

1967-06-01

The main results obtained from this work are the following: 1 Neutron irradiation (at 300 deg. K) produces lattice defects in germanium and silicon, and a corresponding very large lowering of the thermal conductivity is observed in the low temperature region (4-300 ). The results obtained have been explained with the help of the following hypotheses: for silicon a scattering of phonons by the stress fields produced by the defects; for germanium, a supplementary scattering of the electron phonon type. 2 Annealing treatments carried out on these materials above 373 deg. K restored the thermal conductivity over the whole temperature range of the measurements (4-300 deg. K); in the case of both germanium and silicon there were two steps in the annealing process. 3 A study of the thermal conductivity of germanium (initially P or N) after an electronic irradiation showed that the scattering of phonons could depend on the state of charge of the defects thus produced. (author) [fr

Optimization of chemical and instrumental parameters in hydride generation laser-induced breakdown spectrometry for the determination of arsenic, antimony, lead and germanium in aqueous samples.

Science.gov (United States)

Yeşiller, Semira Unal; Yalçın, Serife

2013-04-03

A laser induced breakdown spectrometry hyphenated with on-line continuous flow hydride generation sample introduction system, HG-LIBS, has been used for the determination of arsenic, antimony, lead and germanium in aqueous environments. Optimum chemical and instrumental parameters governing chemical hydride generation, laser plasma formation and detection were investigated for each element under argon and nitrogen atmosphere. Arsenic, antimony and germanium have presented strong enhancement in signal strength under argon atmosphere while lead has shown no sensitivity to ambient gas type. Detection limits of 1.1 mg L(-1), 1.0 mg L(-1), 1.3 mg L(-1) and 0.2 mg L(-1) were obtained for As, Sb, Pb and Ge, respectively. Up to 77 times enhancement in detection limit of Pb were obtained, compared to the result obtained from the direct analysis of liquids by LIBS. Applicability of the technique to real water samples was tested through spiking experiments and recoveries higher than 80% were obtained. Results demonstrate that, HG-LIBS approach is suitable for quantitative analysis of toxic elements and sufficiently fast for real time continuous monitoring in aqueous environments. Copyright © 2013 Elsevier B.V. All rights reserved.

Liquid-helium scintillation detection with germanium photodiodes

International Nuclear Information System (INIS)

Luke, P.N.; Haller, E.E.; Steiner, H.M.

1982-05-01

Special high-purity germanium photodiodes have been developed for the direct detection of vacuum ultraviolet scintillations in liquid helium. The photodiodes are immersed in the liquid helium, and scintillations are detected through one of the bare sides of the photodiodes. Test results with scintillation photons produced by 5.3-MeV α particles are presented. The use of these photodiodes as liquid-helium scintillation detectors may offer substantial improvements over the alternate detection method requiring the use of wavelength shifters and photomultiplier tubes

The Future of Low Temperature Germanium as Dark Matter Detectors

CERN Multimedia

CERN. Geneva

2009-01-01

The Weakly Interactive Massive Particles (WIMPs) represent one of the most attractive candidates for the dark matter in the universe. With the combination of experiments attempting to detect WIMP scattering in the laboratory, of searches for their annihilation in the cosmos and of their potential production at the LHC, the next five years promise to be transformative. I will review the role played so far by low temperature germanium detectors in the direct detection of WIMPs. Because of its high signal to noise ratio, the simultaneous measurement of athermal phonons and ionization is so far the only demonstrated approach with zero-background. I will argue that this technology can be extrapolated to a target mass of the order of a tonne at reasonable cost and can keep playing a leading role, complementary to noble liquid technologies. I will describe in particular GEODM, the proposed Germanium Observatory for Dark Matter at the US Deep Underground Science and Engineering Laboratory (DUSEL).

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.

Volume reflection and channeling of ultrarelativistic protons in germanium bent single crystals

Directory of Open Access Journals (Sweden)

S. Bellucci

2016-12-01

Full Text Available The paper is devoted to the investigation of volume reflection and channeling processes of ultrarelativistic positive charged particles moving in germanium single crystals. We demonstrate that the choice of atomic potential on the basis of the Hartree-Fock method and the correct choice of the Debye temperature allow us to describe the above mentioned processes in a good agreement with the recent experiments. Moreover, the universal form of equations for volume reflection presented in the paper gives a true description of the process at a wide range of particle energies. Standing on this study we make predictions for the mean angle reflection (as a function of the bending radius of positive and negative particles for germanium (110 and (111 crystallographic planes.

Environmental applications for an intrinsic germanium well detector

International Nuclear Information System (INIS)

Stegnar, P.; Eldridge, J.S.; Teasley, N.A.; Oakes, T.W.

1984-01-01

The overall performance of an intrinsic germanium well detector for 125 I measurements was investigated in a program of environmental surveillance. Concentrations of 125 I and 131 I were determined in thyroids of road-killed deer showing the highest activities of 125 I in the animals from the near vicinity of Oak Ridge National Laboratory. This demonstrates the utility of road-killed deer as a bioindicator for radioiodine around nuclear facilities

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.

Numerical evaluation of Auger recombination coefficients in relaxed and strained germanium

Energy Technology Data Exchange (ETDEWEB)

Dominici, Stefano [Dipartimento di Elettronica e Telecomunicazioni, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary' s Street, Boston, Massachusetts 02215 (United States); Wen, Hanqing; Bellotti, Enrico [Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary' s Street, Boston, Massachusetts 02215 (United States); Bertazzi, Francesco; Goano, Michele [Dipartimento di Elettronica e Telecomunicazioni, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); IEIIT-CNR, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)

2016-05-23

The potential applications of germanium and its alloys in infrared silicon-based photonics have led to a renewed interest in their optical properties. In this letter, we report on the numerical determination of Auger coefficients at T = 300 K for relaxed and biaxially strained germanium. We use a Green's function based model that takes into account all relevant direct and phonon-assisted processes and perform calculations up to a strain level corresponding to the transition from indirect to direct energy gap. We have considered excess carrier concentrations ranging from 10{sup 16} cm{sup −3} to 5 × 10{sup 19} cm{sup −3}. For use in device level simulations, we also provide fitting formulas for the calculated electron and hole Auger coefficients as functions of carrier density.

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.

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

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

Recent results on cleaning and conditioning the ATF vacuum system

International Nuclear Information System (INIS)

Langley, R.A.; Clark, T.L.; Glowienka, J.C.; Goulding, R.H.; Mioduszewski, P.K.; Rasmussen, D.A.; Rayburn, T.F.; Schaich, C.R.; Shepard, T.D.; Simpkins, J.E.; Yarber, J.L.

1990-01-01

Techniques for cleaning and conditioning the vacuum vessel of the Advanced Toroidal Facility (ATF) and its internal components are described. The vacuum vessel cleaning technique combines baking to 150 degree C and glow discharges with hydrogen gas. Chromium gettering is used to further condition the system. The major internal components are the anodized aluminum baffles in the Thomson scattering system, a graphite-shielded ICRF antenna, two graphite limiters, and a diagnostic graphite plate. Three independent heating systems are used to bake some of the major components of the system. The major characteristics used for assessing cleanliness and conditioning progress are the maximum pressure attained during bakeout, the results of gas analysis, and revelant plasma parameters (e.g., time to radiative decay). Details of the various cleaning and conditioning procedures and results are presented

Method for atmospheric pressure reactive atom plasma processing for surface modification

Science.gov (United States)

Carr, Jeffrey W [Livermore, CA

2009-09-22

Reactive atom plasma processing can be used to shape, polish, planarize and clean the surfaces of difficult materials with minimal subsurface damage. The apparatus and methods use a plasma torch, such as a conventional ICP torch. The workpiece and plasma torch are moved with respect to each other, whether by translating and/or rotating the workpiece, the plasma, or both. The plasma discharge from the torch can be used to shape, planarize, polish, and/or clean the surface of the workpiece, as well as to thin the workpiece. The processing may cause minimal or no damage to the workpiece underneath the surface, and may involve removing material from the surface of the workpiece.

Removal of carbon contaminations by RF plasma generated reactive species and subsequent effects on optical surface

Energy Technology Data Exchange (ETDEWEB)

Yadav, P. K., E-mail: praveenyadav@rrcat.gov.in; Rai, S. K.; Modi, M. H.; Nayak, M.; Lodha, G. S. [Indus Synchrotron Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India); Kumar, M.; Chakera, J. A.; Naik, P. A. [Laser Plasma Laboratory, Laser Plasma Division, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India)

2015-06-24

Carbon contamination on optical elements is a serious issue in synchrotron beam lines for several decades. The basic mechanism of carbon deposition on optics and cleaning strategies are not fully understood. Carbon growth mechanism and optimized cleaning procedures are worldwide under development stage. Optimized RF plasma cleaning is considered an active remedy for the same. In present study carbon contaminated optical test surfaces (carbon capped tungsten thin film) are exposed for 30 minutes to four different gases, rf plasma at constant power and constant dynamic pressure. Structural characterization (thickness, roughness and density) of virgin samples and plasma exposed samples was done by soft x-ray (λ=80 Å) reflectivity measurements at Indus-1 reflectivity beam line. Different gas plasma removes carbon with different rate (0.4 to 0.65 nm /min). A thin layer 2 to 9 nm of different roughness and density is observed at the top surface of tungsten film. Ar gas plasma is found more suitable for cleaning of tungsten surface.

Laser cleaning of sulfide scale on compressor impeller blade

International Nuclear Information System (INIS)

Tang, Q.H.; Zhou, D.; Wang, Y.L.; Liu, G.F.

2015-01-01

Highlights: • The effects of sulfide layers and fluence values on the mechanism of laser cleaning were experimentally established. • The specimen surface with sulfide scale becomes slightly smoother than that before laser cleaning. • The mechanism of laser cleaning the sulfide scale of stainless steel is spallation without oxidization. • It would avoid chemical waste and dust pollution using a fiber laser instead of using nitric acids or sandblasting. - Abstract: Sulfide scale on the surface of a compressor impeller blade can considerably reduce the impeller performance and its service life. To prepare for subsequent remanufacturing, such as plasma spraying, it needs to be removed completely. In the corrosion process on an FV(520)B stainless steel, sulfide scale is divided into two layers because of different outward diffusion rates of Cr, Ni and Fe. In this paper, the cleaning threshold values of the upper and inner layers and the damage threshold value of the substrate were investigated using a pulsed fiber laser. To obtain experimental evidence, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and 3D surface profilometry were employed to investigate the two kinds of sulfide layers on specimens before, during, and after laser cleaning.

Quadrupole boson densities in the germanium region by inelastic electron scattering

International Nuclear Information System (INIS)

Goutte, D.

1984-08-01

The collective properties of four germanium isotopes have been explored through the measurement of the transition charge densities of the first two 2 + states. Their spatial features and their apparent anomalous behavior is readily explained in the frame of the Interacting Boson Model

Effect of the microstructure on electrical properties of high-purity germanium

Science.gov (United States)

Podkopaev, O. I.; Shimanskii, A. F.; Molotkovskaya, N. O.; Kulakovskaya, T. V.

2013-05-01

The interrelation between the electrical properties and the microstructure of high-purity germanium crystals has been revealed. The electrical conductivity of polycrystalline samples increases and the life-time of nonequilibrium charge carriers in them decreases with a decrease in the crystallite sizes.

Investigation of HF-plasma-treated soft x-ray optical elements

Science.gov (United States)

Eggenstein, F.; Krivenkov, M.; Rudolph, I.; Sertsu, M. G.; Sokolov, A.; Varykhalov, A.; Wolf, J.; Zeschke, T.; Schäfers, F.

2017-09-01

The contamination of optical elements (mirrors and gratings) with carbon still is an issue when using soft x-ray synchrotron radiation. With an in-house developed HF-plasma treatment we are able to decontaminate our optics in-situ from carbon very efficiently. The cleaning device, a simple Al-antenna, is mounted in situ inside the mirror- and grating vacuum chambers. A systematic study of the HF-plasma cleaning efficiency was performed acquired with in-situ and exsitu methods for monitoring: An atomic force microscope (AFM) and a scanning tunneling microscope (STM) were used before and after the cleaning process to determine the surface morphology and roughness. Reflectivity angular scans using the reflectometer at the BESSY-II Metrology Station [1-3] allowed to estimate the thickness of the remaining Clayer after different cleaning steps and thereby helped us to determine the etching rate. Reflection spectra measurements in the range of 200 eV - 900 eV show the complete removal of Carbon from the optics without contaminating it with any other elements due to the plasma treatment. The data show that the plasma process improves the reflectivity and reduces the roughness of the surface. In addition to that, the region of the optical surface where the carbon has been removed becomes passivated.

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

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

Evaluating The Operation Of Three Air Cleaners Working Individually In A Clean Room

DEFF Research Database (Denmark)

Ardkapan, Siamak Rahimi; Afshari, Alireza; Bergsøe, Niels Christian

2011-01-01

The use of portable air cleaners is becoming increasingly popular in many countries including Denmark. Portable air cleaners are known for not only removing but also generating particles and gases. To clarify this, three air cleaning technologies were evaluated. They were nonthermal plasma......, photochemical air purifier and corona discharge ionizer. The concentrations of ultrafine particles, ozone and total volatile organic compounds were measured both in a duct and in a clean room. It was found that the studied air cleaning technologies increased the ozone level in the clean room and the duct....... The increase of ozone level in the clean room was more than that was measured in the duct. Additionally, it was found that the number of ultrafine particles in the room increased due to the generated ozone. The number of generated particles changed with the season. The study leads to the recommendation...

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.

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.)

Germanium-76 Isotope Separation by Cryogenic Distillation. Final Report

International Nuclear Information System (INIS)

Stohler, Eric

2007-01-01

The current separation method for Germanium isotopes is electromagnetic separation using Calutrons. The Calutrons have the disadvantage of having a low separation capacity and a high energy cost to achieve the separation. Our proposed new distillation method has the advantage that larger quantities of Germanium isotopes can be separated at a significantly lower cost and in a much shorter time. After nine months of operating the column that is 1.5 meter in length, no significant separation of the isotopes has been measured. We conclude that the length of the column we have been using is too short. In addition, other packing material than the 0.16 inch Propak, 316 ss Protruded metal packing that we used in the column, should be evaluated which may have a better separation factor than the 0.16 inch Propak, 316 ss Protruded metal packing that has been used. We conclude that a much longer column - a minimum of 50 feet length - should be built and additional column packing should be tested to verify that isotopic separation can be achieved by cryogenic distillation. Even a longer column than 50 feet would be desirable.

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.

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.

Charge Spreading and Position Sensitivity in a Segmented Planar Germanium Detector (Preprint)

National Research Council Canada - National Science Library

Kroeger, R. A; Gehrels, N; Johnson, W. N; Kurfess, J. D; Phlips, B. P; Tueller, J

1998-01-01

The size of the charge cloud collected in a segmented germanium detector is limited by the size of the initial cloud, uniformity of the electric field, and the diffusion of electrons and holes through the detector...

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

Recent results on cleaning and conditioning the ATF vacuum system

International Nuclear Information System (INIS)

Langley, R.A.; Clark, T.L.; Glowienka, J.C.

1989-01-01

Techniques for cleaning and conditioning the vacuum vessel of the Advanced Toroidal Facility (ATF) and its internal components are described. The vacuum vessel cleaning technique combines baking to 150/degree/C and glow discharges with hydrogen gas. Chromium gettering is used to further condition the system. The major internal components are the anodized aluminum baffles in the Thomson scattering system, a graphite-shielded ICRF antenna, two graphite limiters, and a diagnostic graphite plate. Three independent heating systems are used to bake some of the major components of the system. The major characteristics used for assessing cleanliness and conditioning progress are the maximum pressure attained during bakeout, the results of gas analysis, and relevant plasma parameters (e.g., time to radiative decay). Details of the various cleaning and conditioning procedures and results are presented. 5 refs., 8 figs., 3 tabs

Environmental applications for an intrinsic germanium well detector

International Nuclear Information System (INIS)

Stegnar, P.; Eldridge, J.S.; Teasley, N.A.; Oakes, T.W.

1984-01-01

The overall performance of an intrinsic germanium well detector for 125 I measurements was investigated in a program of environmental surveillance. Concentrations of 125 I and 131 I were determined in thyroids of road-killed deer showing the highest activities of 125 I in the animals from the near vicinity of Oak Ridge National Laboratory. This demonstrates the utility of road-killed deer as a bionindicator for radioiodine around nuclear facilities. 6 refs., 2 figs., 3 tabs

Environmental applications for an intrinsic germanium well detector

International Nuclear Information System (INIS)

Stegnar, P.; Eldridge, J.S.; Teasley, N.A.; Oakes, T.W.

1983-01-01

The overall performance of an intrinsic germanium well detector for 125 I measurements was investigated in a program of environmental surveillance. Concentrations of 125 I and 131 I were determined in thyroids of road-killed deer showing the highest activities of 125 I in the animals from the near vicinity of Oak Ridge National Laboratory. This demonstrates the utility of road-killed deer as a bioindicator for radioiodine around nuclear facilities. 6 refs., 2 figs., 3 tabs

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

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

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

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.

Calibration of Single High Purity Germanium Detector for Whole Body Counter

International Nuclear Information System (INIS)

Taha, T.M.; Morsi, T.M.

2009-01-01

A new Accuscan II single germanium detector for whole body counter was installed in NRC (Egypt). The current paper concerned on calibration of single high purity germanium detector for whole body counter. Physical parameters affecting on performance of whole body counter such as linearity, minimum detectable activity and source detector distance, SDD were investigated. Counting efficiencies for the detector have been investigated in rear wall, fixed diagnostic position in air. Counting efficiencies for organ compartments such as thyroid, lung, upper and lower gastrointestinal tract have been investigated using transfer phantom in fixed diagnostic and screening positions respectively. The organ compartment efficiencies in screening geometry were higher than that value of diagnostic geometry by a factor of three. The committed dose equivalents of I-131 in thyroid were ranged from 0.073 ± 0.004 to 1.73±0.09 mSv and in lung was 0.02±0.001 mSv

A high resolution germanium detector array for hypernuclear studies at PANDA

Energy Technology Data Exchange (ETDEWEB)

Bleser, Sebastian; Sanchez Lorente, Alicia; Steinen, Marcell [Helmholtz-Institut Mainz (Germany); Gerl, Juergen; Kojouharova, Jasmina; Kojouharov, Ivan [GSI Darmstadt (Germany); Iazzi, Felice [Politecnico, Torino (Italy); INFN, Torino (Italy); Pochodzalla, Josef; Rittgen, Kai; Sahin, Cihan [Institute for Nuclear Physics, JGU Mainz (Germany)

2014-07-01

The PANDA experiment, planned at the FAIR facility in Darmstadt, aims at the high resolution γ-spectroscopy of double Λ hypernuclei. For this purpose a devoted detector setup is required, consisting of a primary nuclear target, an active secondary target and a germanium detector array for the γ-spectroscopy. Due to the limited space within the PANDA detector a compact design is required. In particular the conventional LN{sub 2} cooling system must be replaced by an electro mechanical device and a new arrangement of the crystals is needed. This presentation shows the progress in the development of the germanium detectors. First results of in-beam measurements at COSY with a new electro mechanically cooled single crystal prototype are presented. Digital pulse shape analysis is used to disentangle pile up events due to the high event rate. This analysis technique also allows to recover the high original energy resolution in case of neutron damage. Finally the status of the new triple crystal detector prototype is given.

Interaction of non-equilibrium phonons with electron-hole plasmas in germanium

International Nuclear Information System (INIS)

Kirch, S.J.

1985-01-01

This thesis presents results of experiments on the interaction of phonons and photo-excited electron-hole plasmas in Ge at low temperature. The first two studies involved the low-temperature fluid phase known as the electron-hole liquid (EHL). The third study involved a wider range of temperatures and includes the higher temperature electron-hole plasma (EHP). In the first experiment, superconducting tunnel junctions are used to produce quasi-monochromatic phonons, which propagate through the EHL. The magnitude of the absorption of these non-equilibrium phonons gives a direct measure of the coupling constant, the deformation potential. In the second experiment, the nonequilibrium phonons are generated by laser excitation of a metal film. An unusual sample geometry allows examination of the EHL-phonon interaction near the EHL excitation surface. This coupling is examined for both cw and pulsed EHL excitation. In the third experiment, the phonons are byproducts of the photo-excited carrier thermalization. The spatial, spectral and temporal dependence of the recombination luminescence is examined. A phonon wind force is observed to dominate the transport properties of the EHL and the EHP. These carriers are never observed to move faster than the phonon velocity even during the laser pulse

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...

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.

Thermophysical Properties of Molten Germanium Measured by the High Temperature Electrostatic Levitator

Science.gov (United States)

Rhim, W. K.; Ishikawa, T.

1998-01-01

Thermophysical properties of molten germanium such as the density, the thermal expansion coefficient, the hemisphereical total emissivity, the constant pressure specific heat capacity, the surface tension, and the electrical resistivity have been measured using the High Temperature Electrostatic Levitator at JPL.

Determination of Shear Deformation Potentials from the Free-Carrier Piezobirefringence in Germanium and Silicon

DEFF Research Database (Denmark)

Riskaer, Sven

1966-01-01

The present investigations of the free-carrier piezobirefringence phenomenon verify that in n-type germanium and silicon as well as in p-type silicon this effect can be ascribed to intraband transitions of the carriers. It is demonstrated how a combined investigation of the low-stress and high......-stress piezobirefringence in these materials provides a direct and independent method for determining deformation-potential constants. For n-type germanium we obtain Ξu=18.0±0.5 eV, for n-type silicon Ξu=8.5±0.4 eV; for p-type silicon a rather crude analytical approximation yields b=-3.1 eV and d=-8.3 eV. Finally...

Induced Radioactivity Measured in a Germanium Detector After a Long Duration Balloon Flight

Science.gov (United States)

Starr, R.; Evans, L. G.; Floyed, S. R.; Drake, D. M.; Feldman, W. C.; Squyres, S. W.; Rester, A. C.

1997-01-01

A 13-day long duration balloon flight carrying a germanium detector was flown from Williams Field, Antartica in December 1992. After recovery of the payload the activity induced in the detector was measured.

Radiation-electromagnetic effect in germanium single crystals

International Nuclear Information System (INIS)

Kikoin, I.K.; Kikoin, L.I.; Lazarev, S.D.

1980-01-01

An experimental study was made of the radiation-electromagnetic effect in germanium single crystals when excess carriers were generated by bombardment with α particles, protons, or x rays in magnetic fields up to 8 kOe. The source of α particles and protons was a cyclotron and x rays were provided by a tube with a copper anode. The radiation-electromagnetic emf increased linearly on increase in the magnetic field and was directly proportional to the flux of charged particles at low values of the flux, reaching saturation at high values of the flux (approx.5 x 10 11 particles .cm -2 .sec -1 ). In the energy range 4--40 MeV the emf was practically independent of the α-particle energy. The sign of the emf was reversed when samples with a ground front surface were irradiated. Measurements of the photoelectromagnetic and Hall effects in the α-particle-irradiated samples showed that a p-n junction was produced by these particles and its presence should be allowed for in investigations of the radiation-electromagnetic effect. The measured even radiation-electromagnetic emf increased quadratically on increase in the magnetic field. An investigation was made of the barrier radiation-voltaic effect (when the emf was measured between the irradiated and unirradiated surfaces). Special masks were used to produce a set of consecutive p-n junctions in germanium crystals irradiated with α particles. A study of the photovoltaic and photoelectromagnetic effects in such samples showed that the method could be used to increase the efficiency of devices utilizing the photoelectromagnetic effect

Comparison of the NaI-CsI phoswich and a hyperpure germanium array for in vivo detection of the actinides

Energy Technology Data Exchange (ETDEWEB)

Berger, C D; Goans, R E [Oak Ridge National Lab., TN (USA)

1981-04-01

An array of hyperpure germanium detectors has recently been employed at ORNL for the identification and quantification of internally deposited actinides. Its advantages over the phoswich detector - the current state-of-the-art for detection of the actinides - were found to be improved background reduction and superior energy resolution. The germanium system and the currently operating phoswich system are discussed and compared. The improvement in performance of the germanium system over the phoswich system (a factor of 2.5 for /sup 239/Pu and 15.3 for /sup 241/Am) appears to justify the financial investment, particularly when /sup 241/Am is used as an indirect means of detection and measurement of /sup 239/Pu.

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

Microwave induced plasma discharge in multi-cell superconducting radio-frequency cavity

International Nuclear Information System (INIS)

Ahmed, Shahid; Mammosser, John D.

2015-01-01

A R&D effort for in situ cleaning of 1.5 GHz Superconducting Radio Frequency (SRF) cavities at room temperature using the plasma processing technique has been initiated at Jefferson Lab. This is a step toward the cleaning of cryomodules installed in the Continuous Electron Beam Accelerator Facility (CEBAF). For this purpose, we have developed an understanding of plasma discharge in a 5-cell CEBAF-type SRF cavity having configurations similar to those in the main accelerator. The focus of this study involves the detailed investigations of developing a plasma discharge inside the cavity volume and avoids the breakdown condition in the vicinity of the ceramic RF window. A plasma discharge of the gas mixture Ar–O 2 (90%:10%) can be established inside the cavity volume by the excitation of a resonant 4π/5 TM 010 -mode driven by a klystron. The absence of any external magnetic field for generating the plasma is suitable for cleaning cavities installed in a complex cryomodule assembly. The procedures developed in these experimental investigations can be applied to any complex cavity structure. Details of these experimental measurements and the observations are discussed in the paper

Microwave induced plasma discharge in multi-cell superconducting radio-frequency cavity

Energy Technology Data Exchange (ETDEWEB)

Ahmed, Shahid, E-mail: shahid.ahmed@ieee.org [BML Munjal University, Gurgaon, Haryana 123413 (India); Mammosser, John D. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2015-07-15

A R&D effort for in situ cleaning of 1.5 GHz Superconducting Radio Frequency (SRF) cavities at room temperature using the plasma processing technique has been initiated at Jefferson Lab. This is a step toward the cleaning of cryomodules installed in the Continuous Electron Beam Accelerator Facility (CEBAF). For this purpose, we have developed an understanding of plasma discharge in a 5-cell CEBAF-type SRF cavity having configurations similar to those in the main accelerator. The focus of this study involves the detailed investigations of developing a plasma discharge inside the cavity volume and avoids the breakdown condition in the vicinity of the ceramic RF window. A plasma discharge of the gas mixture Ar–O{sub 2} (90%:10%) can be established inside the cavity volume by the excitation of a resonant 4π/5 TM{sub 010}-mode driven by a klystron. The absence of any external magnetic field for generating the plasma is suitable for cleaning cavities installed in a complex cryomodule assembly. The procedures developed in these experimental investigations can be applied to any complex cavity structure. Details of these experimental measurements and the observations are discussed in the paper.

Microwave induced plasma discharge in multi-cell superconducting radio-frequency cavity

Science.gov (United States)

Ahmed, Shahid; Mammosser, John D.

2015-07-01

A R&D effort for in situ cleaning of 1.5 GHz Superconducting Radio Frequency (SRF) cavities at room temperature using the plasma processing technique has been initiated at Jefferson Lab. This is a step toward the cleaning of cryomodules installed in the Continuous Electron Beam Accelerator Facility (CEBAF). For this purpose, we have developed an understanding of plasma discharge in a 5-cell CEBAF-type SRF cavity having configurations similar to those in the main accelerator. The focus of this study involves the detailed investigations of developing a plasma discharge inside the cavity volume and avoids the breakdown condition in the vicinity of the ceramic RF window. A plasma discharge of the gas mixture Ar-O2 (90%:10%) can be established inside the cavity volume by the excitation of a resonant 4π/5 TM010-mode driven by a klystron. The absence of any external magnetic field for generating the plasma is suitable for cleaning cavities installed in a complex cryomodule assembly. The procedures developed in these experimental investigations can be applied to any complex cavity structure. Details of these experimental measurements and the observations are discussed in the paper.

Microwave induced plasma discharge in multi-cell superconducting radio-frequency cavity.

Science.gov (United States)

Ahmed, Shahid; Mammosser, John D

2015-07-01

A R&D effort for in situ cleaning of 1.5 GHz Superconducting Radio Frequency (SRF) cavities at room temperature using the plasma processing technique has been initiated at Jefferson Lab. This is a step toward the cleaning of cryomodules installed in the Continuous Electron Beam Accelerator Facility (CEBAF). For this purpose, we have developed an understanding of plasma discharge in a 5-cell CEBAF-type SRF cavity having configurations similar to those in the main accelerator. The focus of this study involves the detailed investigations of developing a plasma discharge inside the cavity volume and avoids the breakdown condition in the vicinity of the ceramic RF window. A plasma discharge of the gas mixture Ar-O2 (90%:10%) can be established inside the cavity volume by the excitation of a resonant 4π/5 TM010-mode driven by a klystron. The absence of any external magnetic field for generating the plasma is suitable for cleaning cavities installed in a complex cryomodule assembly. The procedures developed in these experimental investigations can be applied to any complex cavity structure. Details of these experimental measurements and the observations are discussed in the paper.

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.)

Ecological effectiveness of oil spill countermeasures: how clean is clean?

International Nuclear Information System (INIS)

Baker, J.M.

1999-01-01

This paper with 94 references examines background levels of hydrocarbons and the difficulty of defining clean. Processes and timescales for natural cleaning, and factors affecting natural cleaning timescales are considered. Ecological advantages and disadvantages of clean-up methods are highlighted, and five case histories of oil spills are summarised. The relationships between ecological and socio-economic considerations, and the need for a net environmental benefit analysis which takes into account the advantages and disadvantages of clean-up responses and natural clean-up are discussed. A decision tree for evaluating the requirement for shore clean-up is illustrated. (UK)

dc-Hydrogen plasma induced defects in bulk n-Ge

Energy Technology Data Exchange (ETDEWEB)

Nyamhere, C., E-mail: cloud.nyamhere@nmmu.ac.za [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Venter, A.; Murape, D.M. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Auret, F.D.; Coelho, S.M.M. [Department of Physics, University of the Pretoria, Lynnwood Road, Pretoria 0002 (South Africa); Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa)

2012-08-01

Bulk antimony doped germanium (n-Ge) has been exposed to a dc-hydrogen plasma. Capacitance-voltage depth profiles revealed extensive near surface passivation of the shallow donors as evidenced by {approx}a 1.5 orders of magnitude reduction in the free carrier concentration up to depth of {approx}3.2 {mu}m. DLTS and Laplace-DLTS revealed a prominent electron trap 0.30 eV below the conduction (E{sub C} -0.30 eV). The concentration of this trap increased with plasma exposure time. The depth profile for this defect suggested a uniform distribution up to 1.2 {mu}m. Annealing studies show that this trap, attributed to a hydrogen-related complex, is stable up to 200 Degree-Sign C. Hole traps, or vacancy-antimony centers, common in this material after high energy particle irradiation, were not observed after plasma exposure, an indication that this process does not create Frenkel (V-I) pairs.

dc-Hydrogen plasma induced defects in bulk n-Ge

International Nuclear Information System (INIS)

Nyamhere, C.; Venter, A.; Murape, D.M.; Auret, F.D.; Coelho, S.M.M.; Botha, J.R.

2012-01-01

Bulk antimony doped germanium (n-Ge) has been exposed to a dc-hydrogen plasma. Capacitance-voltage depth profiles revealed extensive near surface passivation of the shallow donors as evidenced by ∼a 1.5 orders of magnitude reduction in the free carrier concentration up to depth of ∼3.2 μm. DLTS and Laplace-DLTS revealed a prominent electron trap 0.30 eV below the conduction (E C -0.30 eV). The concentration of this trap increased with plasma exposure time. The depth profile for this defect suggested a uniform distribution up to 1.2 μm. Annealing studies show that this trap, attributed to a hydrogen-related complex, is stable up to 200 °C. Hole traps, or vacancy-antimony centers, common in this material after high energy particle irradiation, were not observed after plasma exposure, an indication that this process does not create Frenkel (V-I) pairs.

Converting a Microwave Oven into a Plasma Reactor: A Review

Directory of Open Access Journals (Sweden)

Victor J. Law

2018-01-01

Full Text Available This paper reviews the use of domestic microwave ovens as plasma reactors for applications ranging from surface cleaning to pyrolysis and chemical synthesis. This review traces the developments from initial reports in the 1980s to today’s converted ovens that are used in proof-of-principle manufacture of carbon nanostructures and batch cleaning of ion implant ceramics. Information sources include the US and Korean patent office, peer-reviewed papers, and web references. It is shown that the microwave oven plasma can induce rapid heterogeneous reaction (solid to gas and liquid to gas/solid plus the much slower plasma-induced solid state reaction (metal oxide to metal nitride. A particular focus of this review is the passive and active nature of wire aerial electrodes, igniters, and thermal/chemical plasma catalyst in the generation of atmospheric plasma. In addition to the development of the microwave oven plasma, a further aspect evaluated is the development of methodologies for calibrating the plasma reactors with respect to microwave leakage, calorimetry, surface temperature, DUV-UV content, and plasma ion densities.

Neutrino and dark matter physics with sub-keV germanium detectors

Indian Academy of Sciences (India)

2014-11-04

Nov 4, 2014 ... Germanium detectors with sub-keV sensitivities open a window to study neutrino physics to search for light weakly interacting massive particle (WIMP) dark matter. We summarize the recent results on spin-independent couplings of light WIMPs from the TEXONO experiment at the Kuo-Sheng Reactor ...

Modeling of low temperature plasma for surface and Airborne decontamination

NARCIS (Netherlands)

Mihailova, D.; van Dijk, J.; Hagelaar, G.; Belenguer, P.; Guillot, P.

2014-01-01

This paper aims to study and develop new plasma-based technology for the next generation of molecular decontamination systems. A capacitively coupled plasma is considered for cleaning using the plasma fluxes directed to the walls. The model used for this purpose is the PLASIMO fluid module applied

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

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.

Determination of carbon and nitrogen in silicon and germanium

International Nuclear Information System (INIS)

Gebauhr, W.; Martin, J.

1975-01-01

The essential aim of this study is to examine the various technical and economic problems encountered in the determination of carbon and nitrogen in silicon and germanium, for this is in a way an extension of the discussion concerning the presence of oxygen in these two elements. The greater part of the study is aimed at drawing up a catalogue of the methods of analysis used and of the results obtained so far

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.

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.

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.

Violet and visible up-conversion emission in Yb{sup 3+}-Ho{sup 3+} co-doped germanium-borate glasses

Energy Technology Data Exchange (ETDEWEB)

Yang Yanmin, E-mail: mihuyym@163.co [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); Zhang Meixin [Forensic Science Lab, Hebei University, Baoding 071002 (China); Yang Zhiping [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); Fu Zuoling [Key Laboratory of Coherent Light, Atomic and Molecular Spectroscopy, College of physics, Jilin University, Ministry of Education, Changchun 130023 (China)

2010-10-15

The up-conversion emission properties of Yb{sup 3+}-Ho{sup 3+} co-doped germanium-borate glasses have been investigated with 980 nm excitation. The violet, blue, green and red emission bands at about 350, 485, 544 and 653 nm can be identified, respectively. Experimental results indicated that the relative intensity ratios of the peaks I{sub Red}/I{sub Green} increased with increasing B{sub 2}O{sub 3} concentration, which led to changing color of up-conversion emission from green at x=0 to yellow at x=40, to red at x=60. The violet emission at 350 nm was first reported in germanium-borate glass host and up-conversion mechanisms of the emissions were discussed. The Yb{sup 3+}-Ho{sup 3+} co-doped germanium-borate glasses could be an alternative for the generation of violet and primary colors for application in solid-state displays.

A high resolution germanium detector array for hypernuclear studies at PANDA

Energy Technology Data Exchange (ETDEWEB)

Bleser, Sebastian; Sanchez Lorente, Alicia; Steinen, Marcell [Helmholtz-Institut Mainz (Germany); Gerl, Juergen; Kojouharov, Ivan [GSI, Darmstadt (Germany); Iazzi, Felice [Politecnico, Torino, Turin (Italy); INFN, Torino, Turin (Italy); Pochodzalla, Josef; Rittgen, Kai; Sahin, Cihan [Institute for Nuclear Physics, JGU Mainz (Germany); Collaboration: PANDA-Collaboration

2013-07-01

The PANDA experiment, planned at the FAIR facility in Darmstadt, aims at the high resolution γ-spectroscopy of double Λ hypernuclei. For this purpose a devoted detector setup is required, consisting of a primary nuclear target, an active secondary target and a germanium detector array for the γ-spectroscopy. Due to the limited space within the PANDA detector a compact design is required. In particular the conventional LN{sub 2} cooling system must be replaced by an electro-mechanical device and a new arrangement of the crystals is needed. This poster shows the ongoing development of the germanium detectors. Test measurements of a single crystal prototype with an improved cooling concept are shown. Thermal simulations for a triple crystal detector are presented. Aditionally studies of the optimization of the detector arrangement inside the PANDA barrel spectrometer are shown. Finally the status on digital pulse shape analysis is presented which will be necessary to deal with high counting rates and to recover the high original energy resolution in case of neutron damage.

Split Bull's eye shaped aluminum antenna for plasmon-enhanced nanometer scale germanium photodetector.

Science.gov (United States)

Ren, Fang-Fang; Ang, Kah-Wee; Ye, Jiandong; Yu, Mingbin; Lo, Guo-Qiang; Kwong, Dim-Lee

2011-03-09

Bull's eye antennas are capable of efficiently collecting and concentrating optical signals into an ultrasmall area, offering an excellent solution to break the bottleneck between speed and photoresponse in subwavelength photodetectors. Here, we exploit the idea of split bull's eye antenna for a nanometer germanium photodetector operating at a standard communication wavelength of 1310 nm. The nontraditional plasmonic metal aluminum has been implemented in the resonant antenna structure fabricated by standard complementary metal-oxide-semiconductor (CMOS) processing. A significant enhancement in photoresponse could be achieved over the conventional bull's eye scheme due to an increased optical near-field in the active region. Moreover, with this novel antenna design the effective grating area could be significantly reduced without sacrificing device performance. This work paves the way for the future development of low-cost, high-density, and high-speed CMOS-compatible germanium-based optoelectronic devices.

Empirical correction of crosstalk in a low-background germanium γ-γ analysis system

International Nuclear Information System (INIS)

Keillor, M.E.; Erikson, L.E.; Aalseth, C.E.; Day, A.R.; Fuller, E.S.; Glasgow, B.D.; Hoppe, E.W.; Hossbach, T.W.; Mizouni, L.K.; Myers, A.W.

2013-01-01

The Pacific Northwest National Laboratory (PNNL) is currently developing a custom software suite capable of automating many of the tasks required to accurately analyze coincident signals within gamma spectrometer arrays. During the course of this work, significant crosstalk was identified in the energy determination for spectra collected with a new low-background intrinsic germanium (HPGe) array at PNNL. The HPGe array is designed for high detection efficiency, ultra-low-background performance, and sensitive γ-γ coincidence detection. The first half of the array, a single cryostat containing seven HPGe crystals, was recently installed into a new shallow underground laboratory facility. This update will present a brief review of the germanium array, describe the observed crosstalk, and present a straight-forward empirical correction that significantly reduces the impact of this crosstalk on the spectroscopic performance of the system. (author)

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.

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.

An Implant-Passivated Blocked Impurity Band Germanium Detector for the Far Infrared, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — We propose to investigate the feasibility of fabricating a germanium blocked-impurity-band (BIB) detector using a novel process which will enable us to: 1- fabricate...

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.

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.

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

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

Dosimetric properties of germanium doped calcium borate glass subjected to 6 MV and 10 MV X-ray irradiations

Science.gov (United States)

Tengku Kamarul Bahri, T. N. H.; Wagiran, H.; Hussin, R.; Saeed, M. A.; Hossain, I.; Ali, H.

2014-10-01

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.

An Implant-Passivated Blocked Impurity Band Germanium Detector for the Far Infrared, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — We propose to fabricate a germanium blocked-impurity-band (BIB) detector using a novel process which will enable us to: 1- fabricate a suitably-doped active layer...

Controlling the cost of clean air - A new clean coal technology

International Nuclear Information System (INIS)

Kindig, J.K.; Godfrey, R.L.

1991-01-01

This article presents the authors' alternative to expensive coal combustion products clean-up by cleaning the coal, removing the sulfur, before combustion. Topics discussed include sulfur in coal and the coal cleaning process, the nature of a new coal cleaning technology, the impact on Clean Air Act compliance, and the economics of the new technology

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.

AC/DC/pulsed-power modulator for corona-plasma generation

NARCIS (Netherlands)

Ariaans, T.H.P.; Pemen, A.J.M.; Winands, G.J.J.; Heesch, van E.J.M.; Liu, Z.

2009-01-01

Gas-cleaning techniques using nonthermal plasma are slowly introduced into industry nowadays. In this paper, we present a novel power modulator for the efficient generation of large-volume corona plasma. No expensive high-voltage components are required. Switching is done at an intermediate voltage

Radio frequency plasma excitation

International Nuclear Information System (INIS)

Burden, M.St.J.; Cross, K.B.

1979-01-01

An investigation into the use of rf sputtering for ion cleaning of insulating substrates before ion plating is reported. Initial experiments consisted of sputtering metals with rf power followed by the deposition of copper onto glass slides using rf plasma excitation and biasing supply. It was found that good quality films were obtained by rf ion plating onto plastics with excellent adhesion over a wide operating pressure range. A block schematic of the rf plasma excitation system is shown. (UK)

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

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.

Deformation potentials for band-to-band tunneling in silicon and germanium from first principles

Science.gov (United States)

Vandenberghe, William G.; Fischetti, Massimo V.

2015-01-01

The deformation potentials for phonon-assisted band-to-band tunneling (BTBT) in silicon and germanium are calculated using a plane-wave density functional theory code. Using hybrid functionals, we obtain: DTA = 4.1 × 108 eV/cm, DTO = 1.2 × 109 eV/cm, and DLO = 2.2 × 109 eV/cm for BTBT in silicon and DTA = 7.8 × 108 eV/cm and DLO = 1.3 × 109 eV/cm for BTBT in germanium. These values agree with experimentally measured values and we explain why in diodes, the TA/TO phonon-assisted BTBT dominates over LO phonon-assisted BTBT despite the larger deformation potential for the latter. We also explain why LO phonon-assisted BTBT can nevertheless dominate in many practical applications.

The germanium wall of the GEM detector system GEM Collaboration

International Nuclear Information System (INIS)

Betigeri, M.; Biakowski, E.; Bojowald, H.; Budzanowski, A.; Chatterjee, A.; Drochner, M.; Ernst, J.; Foertsch, S.; Freindl, L.; Frekers, D.; Garske, W.; Grewer, K.; Hamacher, A.; Igel, S.; Ilieva, J.; Jarczyk, L.; Jochmann, M.; Kemmerling, G.; Kilian, K.; Kliczewski, S.; Klimala, W.; Kolev, D.; Kutsarova, T.; Lieb, J.; Lippert, G.; Machner, H.; Magiera, A.; Nann, H.; Pentchev, L.; Plendl, H.S.; Protic, D.; Razen, B.; Rossen, P. von; Roy, B.J.; Siudak, R.; Smyrski, J.; Srikantiah, R.V.; Strzakowski, A.; Tsenov, R.; Zolnierczuk, P.A.; Zwoll, K.

1999-01-01

A stack of annular detectors made of high-purity germanium was developed. The detectors are position sensitive with radial structures. The first one ('Quirl') is double-sided position sensitive defining 40,000 pixels, the following three (E1, E2 and E3) have 32 wedges each. The Quirl acts as tracker while the other three act as calorimeter. The stack was successfully operated in meson production reactions close to threshold

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

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

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.

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

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

Discharge cleaning and wall conditioning in a Novillo Tokamak

CERN Document Server

Valencia, R; Camps, E; Contreras, G; Muhl, S

2002-01-01

Our Novillo Tokamak is a small toroidal device magnetically confined defined by the main design parameters: R sub o =0.23 m, a sub v =0.08 m, a sub p =0.06 m, B sub T =0.05-0.47 T, I sub p =1-12 kA, n sub e =1-2x10 sup 1 sup 3 cm sup - sup 3 , T sub e =150 eV, T sub i =50 eV. For the initial discharge chamber cleaning we have often used vacuum baking up to 100 deg. C and then conditioning using Taylor discharge cleaning (TDC) in H sub 2 and He. In this work we report that vacuum baking is effective for obtaining a final total pressure of the order of 1.6x10 sup - sup 7 Torr. We have found that a single parameter, the performance parameter (PP), can be used to optimize the TDC method. This parameter represents the quantity of electron and ion energy incident on the chamber wall during the Taylor discharge, it is equal to (I sub p tau), where I sub p is the peak-to-peak plasma current and tau is the plasma current duration. In graphs of PP versus the gas pressure for different oscillator powers, the maximum val...

In situ dc oxygen‐discharge cleaning system for optical elements

International Nuclear Information System (INIS)

Koide, Tsuneharu; Shidara, Tetsuo; Tanaka, Kenichiro; Yagishita, Akira; Sato, Shigeru

1989-01-01

In situ dc oxygen‐discharge cleaning arrangements have been developed at the Photon Factory for the removal of carbon contamination from optical surfaces. A high cleaning rate could be achieved by producing an oxygen plasma close to the optical elements with special care taken to avoid any harmful effects from the discharge; contaminant carbon was completely removed within a few hours, at most. This short exposure time and the use of dry oxygen gas resulted in a restoration of the original ultrahigh vacuum without a bakeout. Results with a Seya‐Namioka beamline for gas‐phase experiments showed a flux enhancement amounting to a factor of 50, and results with a grasshopper beamline showed a nearly complete recovery of the light intensity, even at the carbon K edge

In situ dc oxygen-discharge cleaning system for optical elements

International Nuclear Information System (INIS)

Koide, T.; Shidara, T.; Tanaka, K.; Yagishita, A.; Sato, S.

1989-01-01

In situ dc oxygen-discharge cleaning arrangements have been developed at the Photon Factory for the removal of carbon contamination from optical surfaces. A high cleaning rate could be achieved by producing an oxygen plasma close to the optical elements with special care taken to avoid any harmful effects from the discharge; contaminant carbon was completely removed within a few hours, at most. This short exposure time and the use of dry oxygen gas resulted in a restoration of the original ultrahigh vacuum without a bakeout. Results with a Seya-Namioka beamline for gas-phase experiments showed a flux enhancement amounting to a factor of 50, and results with a grasshopper beamline showed a nearly complete recovery of the light intensity, even at the carbon K edge

Optical properties of highly n-doped germanium obtained by in situ doping and laser annealing

Science.gov (United States)

Frigerio, J.; Ballabio, A.; Gallacher, K.; Giliberti, V.; Baldassarre, L.; Millar, R.; Milazzo, R.; Maiolo, L.; Minotti, A.; Bottegoni, F.; Biagioni, P.; Paul, D.; Ortolani, M.; Pecora, A.; Napolitani, E.; Isella, G.

2017-11-01

High n-type doping in germanium is essential for many electronic and optoelectronic applications especially for high performance Ohmic contacts, lasing and mid-infrared plasmonics. We report on the combination of in situ doping and excimer laser annealing to improve the activation of phosphorous in germanium. An activated n-doping concentration of 8.8  ×  1019 cm-3 has been achieved starting from an incorporated phosphorous concentration of 1.1  ×  1020 cm-3. Infrared reflectivity data fitted with a multi-layer Drude model indicate good uniformity over a 350 nm thick layer. Photoluminescence demonstrates clear bandgap narrowing and an increased ratio of direct to indirect bandgap emission confirming the high doping densities achieved.

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

Debris-free rear-side picosecond laser ablation of thin germanium wafers in water with ethanol

International Nuclear Information System (INIS)

Zhang, Dongshi; Gökce, Bilal; Sommer, Steffen; Streubel, René; Barcikowski, Stephan

2016-01-01

Graphical abstract: - Highlights: • Picosecond laser cutting of fragile 150 μm thin germanium wafers (typically used for solar cell applications) in liquid results in debris-free surfaces. • Liquid-assisted laser cutting is much better than air-assisted laser cutting in terms of recast, debris and cleanness of the resultant grooves. • Laser cutting in ethanol–water mixtures result in better cut quality than those performed in pure water but lead to less cutting efficiency. • Low repetition rate (10 kHz), mixed solution (1 wt% ethanol in water) and moderate scanning speed (100 μm/s) are preferable for ultrafine high-quality debris-free cutting. - Abstract: In this paper, we perform liquid-assisted picosecond laser cutting of 150 μm thin germanium wafers from the rear side. By investigating the cutting efficiency (the ability to allow an one-line cut-through) and quality (characterized by groove morphologies on both sides), the pros and cons of this technique under different conditions are clarified. Specifically, with laser fluence fixed, repetition rate and scanning speed are varied to show quality and efficiency control by means of laser parameter modulation. It is found that low repetition rate ablation in liquid gives rise to a better cut quality on the front side than high repetition rate ablation since it avoids dispersed nanoparticles redeposition resulting from a bubble collapse, unlike the case of 100 kHz which leads to large nanorings near the grooves resulting from a strong interaction of bubbles and the case of 50 kHz which leads to random cutting due to the interaction of the former pulse induced cavitation bubble and the subsequent laser pulse. Furthermore, ethanol is mixed with pure distilled water to assess the liquid's impact on the cutting efficiency and cutting quality. The results show that increasing the ethanol fraction decreases the ablation efficiency but simultaneously, greatly improves the cutting quality. The improvement of

Debris-free rear-side picosecond laser ablation of thin germanium wafers in water with ethanol

Energy Technology Data Exchange (ETDEWEB)

Zhang, Dongshi; Gökce, Bilal [Technical Chemistry I and Center for Nanointegration, Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitaetsstrasse 7, 45141 Essen (Germany); Sommer, Steffen [Dausinger & Giesen GmbH, Rotebühlstrasse 87, 70178 Stuttgart (Germany); Streubel, René [Technical Chemistry I and Center for Nanointegration, Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitaetsstrasse 7, 45141 Essen (Germany); Barcikowski, Stephan, E-mail: stephan.barcikowski@uni-due.de [Technical Chemistry I and Center for Nanointegration, Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitaetsstrasse 7, 45141 Essen (Germany)

2016-03-30

Graphical abstract: - Highlights: • Picosecond laser cutting of fragile 150 μm thin germanium wafers (typically used for solar cell applications) in liquid results in debris-free surfaces. • Liquid-assisted laser cutting is much better than air-assisted laser cutting in terms of recast, debris and cleanness of the resultant grooves. • Laser cutting in ethanol–water mixtures result in better cut quality than those performed in pure water but lead to less cutting efficiency. • Low repetition rate (10 kHz), mixed solution (1 wt% ethanol in water) and moderate scanning speed (100 μm/s) are preferable for ultrafine high-quality debris-free cutting. - Abstract: In this paper, we perform liquid-assisted picosecond laser cutting of 150 μm thin germanium wafers from the rear side. By investigating the cutting efficiency (the ability to allow an one-line cut-through) and quality (characterized by groove morphologies on both sides), the pros and cons of this technique under different conditions are clarified. Specifically, with laser fluence fixed, repetition rate and scanning speed are varied to show quality and efficiency control by means of laser parameter modulation. It is found that low repetition rate ablation in liquid gives rise to a better cut quality on the front side than high repetition rate ablation since it avoids dispersed nanoparticles redeposition resulting from a bubble collapse, unlike the case of 100 kHz which leads to large nanorings near the grooves resulting from a strong interaction of bubbles and the case of 50 kHz which leads to random cutting due to the interaction of the former pulse induced cavitation bubble and the subsequent laser pulse. Furthermore, ethanol is mixed with pure distilled water to assess the liquid's impact on the cutting efficiency and cutting quality. The results show that increasing the ethanol fraction decreases the ablation efficiency but simultaneously, greatly improves the cutting quality. The improvement

Hydrogen plasma treatment of silicon dioxide for improved silane deposition.

Science.gov (United States)

Gupta, Vipul; Madaan, Nitesh; Jensen, David S; Kunzler, Shawn C; Linford, Matthew R

2013-03-19

We describe a method for plasma cleaning silicon surfaces in a commercial tool that removes adventitious organic contamination and enhances silane deposition. As shown by wetting, ellipsometry, and XPS, hydrogen, oxygen, and argon plasmas effectively clean Si/SiO2 surfaces. However, only hydrogen plasmas appear to enhance subsequent low-pressure chemical vapor deposition of silanes. Chemical differences between the surfaces were confirmed via (i) deposition of two different silanes: octyldimethylmethoxysilane and butyldimethylmethoxysilane, as evidenced by spectroscopic ellipsometry and wetting, and (ii) a principal components analysis (PCA) of TOF-SIMS data taken from the different plasma-treated surfaces. AFM shows no increase in surface roughness after H2 or O2 plasma treatment of Si/SiO2. The effects of surface treatment with H2/O2 plasmas in different gas ratios, which should allow greater control of surface chemistry, and the duration of the H2 plasma (complete surface treatment appeared to take place quickly) are also presented. We believe that this work is significant because of the importance of silanes as surface functionalization reagents, and in particular because of the increasing importance of gas phase silane deposition.

Atmospheric pressure plasma cleaning of contamination surfaces. 1997 mid-year progress report

International Nuclear Information System (INIS)

Hicks, R.; Selwyn, G.S.

1997-01-01

'Goals of the project are to (1) identify the key physics and chemistry underlying the use of high pressure plasmas for etching removal of actinides and actinide surrogates; and (2) identify key surface reactions and plasma physics necessary for optimization of the atmospheric pressure plasma jet. Technical description of the work decommissioning of transuranic waste (TRU) into low-level radioactive waste (LLW) represents the largest cleanup cost associated with the nuclear weapons complex. This work is directed towards developing a low-cost plasma technology capable of converting TRU into LLW, based upon highly selective plasma etching of plutonium and other actinides from contaminated surfaces. In this way, only the actinide material is removed, leaving the surface less contaminated. The plasma etches actinide material by producing a volatile halide compound, which may be efficiently trapped using filters. To achieve practical, low-cost operation of a plasma capable of etching actinide materials, the authors have developed a y-mode, resonant-cavity, atmospheric pressure plasma jet (APPJ). In contrast to conventional, low pressure plasmas, the APPJ produces a purely-chemical effluent free of ions, and so achieves very high selectivity and produces negligible damage to the surface. Since the jet operates outside a chamber, many nuclear wastes may be treated including machinery, duct-work, concrete and other building materials. In some cases, it may be necessary to first remove paint from contaminated surfaces using a plasma selective for that surface, then to switch to the actinide etching chemistry for removal of actinide contamination. The goal of this work is to develop the underlying science required for maturation of this technology and to establish early version engineering prototypes. Accomplishments to Date The authors have made significant progress in this program. The work conducted jointly at Los Alamos and at UCLA. This has been facilitated by exchange

Atmospheric pressure plasma cleaning of contamination surfaces. 1997 mid-year progress report

Energy Technology Data Exchange (ETDEWEB)

Selwyn, G.S. [Los Alamos National Lab., NM (US); Hicks, R. [Univ. of California, Los Angeles, CA (US)

1997-06-01

'Goals of the project are to (1) identify the key physics and chemistry underlying the use of high pressure plasmas for etching removal of actinides and actinide surrogates; and (2) identify key surface reactions and plasma physics necessary for optimization of the atmospheric pressure plasma jet. Technical description of the work decommissioning of transuranic waste (TRU) into low-level radioactive waste (LLW) represents the largest cleanup cost associated with the nuclear weapons complex. This work is directed towards developing a low-cost plasma technology capable of converting TRU into LLW, based upon highly selective plasma etching of plutonium and other actinides from contaminated surfaces. In this way, only the actinide material is removed, leaving the surface less contaminated. The plasma etches actinide material by producing a volatile halide compound, which may be efficiently trapped using filters. To achieve practical, low-cost operation of a plasma capable of etching actinide materials, the authors have developed a y-mode, resonant-cavity, atmospheric pressure plasma jet (APPJ). In contrast to conventional, low pressure plasmas, the APPJ produces a purely-chemical effluent free of ions, and so achieves very high selectivity and produces negligible damage to the surface. Since the jet operates outside a chamber, many nuclear wastes may be treated including machinery, duct-work, concrete and other building materials. In some cases, it may be necessary to first remove paint from contaminated surfaces using a plasma selective for that surface, then to switch to the actinide etching chemistry for removal of actinide contamination. The goal of this work is to develop the underlying science required for maturation of this technology and to establish early version engineering prototypes. Accomplishments to Date The authors have made significant progress in this program. The work conducted jointly at Los Alamos and at UCLA. This has been facilitated by

Self-absorption corrections for well-type germanium detectors

International Nuclear Information System (INIS)

Appleby, P.G.; Richardson, N.; Nolan, P.J.

1992-01-01

Corrections for self-absorption are of vital importance to accurate determination by gamma spectrometry of radionuclides such as 210 Pb, 241 Am and 234 Th which emit low energy gamma radiation. A simple theoretical model for determining the necessary corrections for well-type germanium detectors is presented. In this model, self-absorption factors are expressed in terms of the mass attenuation coefficient of the sample and a parameter characterising the well geometry. Experimental measurements of self-absorption are used to evaluate the model and to determine a semi-empirical algorithm for improved estimates of the geometrical parameter. (orig.)

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

Surface chemistry of carbon removal from indium tin oxide by base and plasma treatment, with implications on hydroxyl termination

International Nuclear Information System (INIS)

Chaney, John A.; Koh, Sharon E.; Dulcey, Charles S.; Pehrsson, Pehr E.

2003-01-01

The surface chemistry of carbon removal from indium tin oxide (ITO) has been investigated with Auger electron spectroscopy (AES), high-resolution electron energy loss spectroscopy (HREELS), and high-resolution energy loss spectroscopy (HR-ELS). A vibrating Kelvin probe (KP) was used to monitor the work function (PHI) of ITO after cleaning, either by base-cleaning with alcoholic-KOH or by O 2 plasma-cleaning. Base-cleaning lowered PHI ITO as seen in the KP analysis, whereas plasma-cleaning slightly increased PHI ITO by an oxidative process. The degree of PHI ITO depression by base-cleaning was seen to depend on the initial surface, but the PHI depression itself was nonreductive to the ITO, as seen in the In-MNN AES lineshape. The nonreductive depression of PHI ITO by base-cleaning was further supported by a constant charge carrier density, as estimated from the HR-ELS. Base-cleaning was slightly more effective than the oxygen plasma in removing carbon from the ITO surface. However, base-cleaning preferentially removed graphitic carbon while leaving significant hydrocarbon contaminants, as determined by vibrational analysis with HREELS. All other ITO surfaces retained a significant carbon and hydrocarbon contamination as evidenced by AES and HREELS. There was little evidence of the formation of surface hydroxyl species, as expected for such an inherently contaminated surface as ITO

Overview of material migration and mixing, fuel retention and cleaning of ITER-like castellated structures in TEXTOR

International Nuclear Information System (INIS)

Litnovsky, A.; Philipps, V.; Wienhold, P.; Kreter, A.; Kirschner, A.; Matveev, D.; Brezinsek, S.; Sergienko, G.; Pospieszczyk, A.; Schweer, B.; Schulz, C.; Schmitz, O.; Coenen, J.W.; Samm, U.; Krieger, K.; Hirai, T.; Emmoth, B.; Rubel, M.; Bazylev, B.; Breuer, U.

2011-01-01

Plasma-facing components (PFCs) in ITER will be castellated by splitting them into small-size blocks to maintain the thermo-mechanical stability. However, there are concerns in particular on retention of codeposited radioactive fuel in the gaps. An R and D program is underway in TEXTOR addressing this acute issue of castellation. Material migration and fuel inventory are investigated using long- and short-term discharge-resolved experiments with castellated structures in TEXTOR. Significant impurity transport to the gaps was detected and results were in part quantitatively reproduced with 3D-GAPS code. Deposits containing up to 70 at.% of tungsten on the gap areas closest to the plasma were detected in recent experiments. Deposition in the gaps accompanied by metal mixing demand for development of effective cleaning techniques. In experiments with ITER-like castellation, the gaps were cleaned from carbonaceous deposits using oxygen plasmas at 350 deg. C. This contribution contains an overview of experimental and modeling results along with recommendations for PFCs in ITER.

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.

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

Performances in Tank Cleaning

Directory of Open Access Journals (Sweden)

Fanel-Viorel Panaitescu

2018-03-01

Full Text Available There are several operations which must do to maximize the performance of tank cleaning. The new advanced technologies in tank cleaning have raised the standards in marine areas. There are many ways to realise optimal cleaning efficiency for different tanks. The evaluation of tank cleaning options means to start with audit of operations: how many tanks require cleaning, are there obstructions in tanks (e.g. agitators, mixers, what residue needs to be removed, are cleaning agents required or is water sufficient, what methods can used for tank cleaning. After these steps, must be verify the results and ensure that the best cleaning values can be achieved in terms of accuracy and reliability. Technology advancements have made it easier to remove stubborn residues, shorten cleaning cycle times and achieve higher levels of automation. In this paper are presented the performances in tank cleaning in accordance with legislation in force. If tank cleaning technologies are effective, then operating costs are minimal.

A small diameter, flexible, all attitude, self-contained germanium spectrometer. Operator's manual

International Nuclear Information System (INIS)

Bordzindki, R.L.; Lepel, E.A.; Reeves, J.H.; Kohli, R.

1997-05-01

The end of the Cold War has brought about tremendous changes in the nuclear complex of the Department of Energy. One of the many changes has been the shutdown or decommissioning of many facilities that performed nuclear work. One of the steps in the process of decommissioning a facility involves the decontamination or removal of drain lines or pipes that may have carried radioactive materials at one time. The removal of all these pipes and drain lines to a nuclear disposal facility could be quite costly. It was suggested by Pacific Northwest National Laboratory (PNNL) that a germanium spectrometer could be built that could fit through straight pipes with a diameter as small as 5.08 cm (2 inches) and pass through curved pipes with a diameter as small as 7.6 cm (3 inches) such as that of a 3-inch p-trap in a drain line. The germanium spectrometer could then be used to simultaneously determine all gamma-ray emitting radionuclides in or surrounding the pipe. By showing the absence of any gamma-ray emitting radionuclides, the pipes could then be reused in place or disposed of as non-radioactive material, thus saving significantly in disposal costs. A germanium spectrometer system has been designed by PNNL and fabricated by Princeton Gamma Tech (PGT) that consists of three segments, each 4.84 cm in diameter and about 10 cm in length. Flexible stainless steel bellows were used to connect the segments. Segment 1 is a small liquid nitrogen reservoir. The reservoir is filled with a sponge-like material which enables the detector to be used in any orientation. A Stirling cycle refrigerator is under development which can replace the liquid nitrogen reservoir to provide continuous cooling and operation

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

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.

Continuously tunable photonic fractional Hilbert transformer using a high-contrast germanium-doped silica-on-silicon microring resonator.

Science.gov (United States)

Shahoei, Hiva; Dumais, Patrick; Yao, Jianping

2014-05-01

We propose and experimentally demonstrate a continuously tunable fractional Hilbert transformer (FHT) based on a high-contrast germanium-doped silica-on-silicon (SOS) microring resonator (MRR). The propagation loss of a high-contrast germanium-doped SOS waveguide can be very small (0.02 dB/cm) while the lossless bend radius can be less than 1 mm. These characteristics lead to the fabrication of an MRR with a high Q-factor and a large free-spectral range (FSR), which is needed to implement a Hilbert transformer (HT). The SOS MRR is strongly polarization dependent. By changing the polarization direction of the input signal, the phase shift introduced at the center of the resonance spectrum is changed. The tunable phase shift at the resonance wavelength can be used to implement a tunable FHT. A germanium-doped SOS MRR with a high-index contrast of 3.8% is fabricated. The use of the fabricated MRR for the implementation of a tunable FHT with tunable orders at 1, 0.85, 0.95, 1.05, and 1.13 for a Gaussian pulse with the temporal full width at half-maximum of 80 ps is experimentally demonstrated.

Method and apparatus for monitoring plasma processing operations

Science.gov (United States)

Smith, Jr., Michael Lane; Ward, Pamela Denise Peardon; Stevenson, Joel O'Don

2002-01-01

The invention generally relates to various aspects of a plasma process, and more specifically the monitoring of such plasma processes. One aspect relates in at least some manner to calibrating or initializing a plasma monitoring assembly. This type of calibration may be used to address wavelength shifts, intensity shifts, or both associated with optical emissions data obtained on a plasma process. A calibration light may be directed at a window through which optical emissions data is being obtained to determine the effect, if any, that the inner surface of the window is having on the optical emissions data being obtained therethrough, the operation of the optical emissions data gathering device, or both. Another aspect relates in at least some manner to various types of evaluations which may be undertaken of a plasma process which was run, and more typically one which is currently being run, within the processing chamber. Plasma health evaluations and process identification through optical emissions analysis are included in this aspect. Yet another aspect associated with the present invention relates in at least some manner to the endpoint of a plasma process (e.g., plasma recipe, plasma clean, conditioning wafer operation) or discrete/discernible portion thereof (e.g., a plasma step of a multiple step plasma recipe). Another aspect associated with the present invention relates to how one or more of the above-noted aspects may be implemented into a semiconductor fabrication facility, such as the distribution of wafers to a wafer production system. A final aspect of the present invention relates to a network a plurality of plasma monitoring systems, including with remote capabilities (i.e., outside of the clean room).

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.

Clean Cities Fact Sheet

Energy Technology Data Exchange (ETDEWEB)

2004-01-01

This fact sheet explains the Clean Cities Program and provides contact information for all coalitions and regional offices. It answers key questions such as: What is the Clean Cities Program? What are alternative fuels? How does the Clean Cities Program work? What sort of assistance does Clean Cities offer? What has Clean Cities accomplished? What is Clean Cities International? and Where can I find more information?

Germanium detectors for nuclear spectroscopy: Current research and development activity at LNL

Energy Technology Data Exchange (ETDEWEB)

Napoli, D. R., E-mail: daniel.r.napoli@lnl.infn.it [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Viale dell’Università 2, 35020 Legnaro, Padova (Italy); Maggioni, G., E-mail: maggioni@lnl.infn.it; Carturan, S.; Gelain, M. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Viale dell’Università 2, 35020 Legnaro, Padova (Italy); Department of Physics and Astronomy “G. Galilei”, University of Padova, Via Marzolo 8, 35121 Padova (Italy); Eberth, J. [Institut für Kernphysik, Universität zu Köln, Zülpicher Straße 77, D-50937 Köln (Germany); Grimaldi, M. G.; Tatí, S. [Department of Physics and Astronomy, University of Catania (Italy); Riccetto, S. [University of Camerino and INFN of Perugia (Italy); Mea, G. Della [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Viale dell’Università 2, 35020 Legnaro, Padova (Italy); University of Trento (Italy)

2016-07-07

High-purity Germanium (HPGe) detectors have reached an unprecedented level of sophistication and are still the best solution for high-resolution gamma spectroscopy. In the present work, we will show the results of the characterization of new surface treatments for the production of these detectors, studied in the framework of our multidisciplinary research program in HPGe detector technologies.

Laser surface cleaning

International Nuclear Information System (INIS)

Freiwald, J.G.; Freiwald, D.A.

1994-01-01

The objective of this work is a laboratory demonstration that red-lead primer and two-part epoxy paints can be stripped from concrete and metal surfaces using surface cleaning systems based on pulsed-repetition CO 2 lasers. The three goals are to: (1) demonstrate coatings removal, including surface pore cleaning; (2) demonstrate that there is negligible release of ablated contaminants to the environment; and (3) demonstrate that the process will generate negligible amounts of additional waste compared to competing technologies. Phase 1 involved site visits to RMI and Fernald to assess the cleaning issues for buildings and parts. In addition, Phase 1 included detailed designs of a more powerful system for industrial cleaning rates, including laser, articulating optics, ablated-material capture suction nozzle attached to a horizontal raster scanner for floor cleaning, and filtration system. Some concept development is also being done for using robots, and for parts cleaning. In Phase 2 a transportable 6 kW system will be built and tested, with a horizontal surface scanner for cleaning paint from floors. The laboratory tests will again be instrumented. Some concept development will continue for using robots, and for parts cleaning. This report describes Phase 1 results

Optical properties of highly n-doped germanium obtained by in situ doping and laser annealing

International Nuclear Information System (INIS)

Frigerio, J; Ballabio, A; Isella, G; Gallacher, K; Millar, R; Paul, D; Gilberti, V; Baldassarre, L; Ortolani, M; Milazzo, R; Napolitani, E; Maiolo, L; Minotti, A; Pecora, A; Bottegoni, F; Biagioni, P

2017-01-01

High n-type doping in germanium is essential for many electronic and optoelectronic applications especially for high performance Ohmic contacts, lasing and mid-infrared plasmonics. We report on the combination of in situ doping and excimer laser annealing to improve the activation of phosphorous in germanium. An activated n-doping concentration of 8.8  ×  10 19 cm −3 has been achieved starting from an incorporated phosphorous concentration of 1.1  ×  10 20 cm −3 . Infrared reflectivity data fitted with a multi-layer Drude model indicate good uniformity over a 350 nm thick layer. Photoluminescence demonstrates clear bandgap narrowing and an increased ratio of direct to indirect bandgap emission confirming the high doping densities achieved. (paper)

Photoconductivity of Germanium Nanowire Arrays Incorporated in Anodic Aluminum Oxide

International Nuclear Information System (INIS)

Polyakov, B; Prikulis, J; Grigorjeva, L; Millers, D; Daly, B; Holmes, J D; Erts, D

2007-01-01

Photoconductivity of germanium nanowire arrays of 50 and 100 nm diameter incorporated into Anodic Aluminum Oxide (AAO) membranes illuminated with visible light is investigated. Photocurrent response to excitation radiation with time constants faster than 10 -4 s were governed by absorption of incident light by nanowires, while photokinetics with time constants of the order of 10 -3 s originates from the photoluminescence of the AAO matrix. Possible applications of nanowire arrays inside AAO as photoresistors are discussed

Radiation defects produced by neutron irradiation in germanium single crystals

International Nuclear Information System (INIS)

Fukuoka, Noboru; Honda, Makoto; Atobe, Kozo; Yamaji, Hiromichi; Ide, Mutsutoshi; Okada, Moritami.

1992-01-01

The nature of defects produced in germanium single crystals by neutron irradiation at 25 K was studied by measuring the electrical resistivity. It was found that two levels located at E c -0.06 eV and E c -0.13 eV were introduced in an arsenic-doped sample. Electron traps at E c -0.10eV were observed in an indium-doped sample. The change in electrical resistivity during irradiation was also studied. (author)

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 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.

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)

Ultra-clean

International Nuclear Information System (INIS)

Hergenroether, K.

1987-01-01

No other method guarantees such a thorough cleaning of contaminated materials' surfaces. Only ultrasound can reach those cavities crevices and corners where any manual cleaning fails. Furthermore there is no cumbersome and time-consuming manual decontamination which often has to be carried out in glove boxes and hot cells. Depending on the design the cleaning effect can reach from removing adhering dirt particles to removing complete surface layers. (orig./PW) [de

Clean Energy Solutions Center: Assisting Countries with Clean Energy Policy

Science.gov (United States)

advice on financing instruments. In a recent keynote to the Climate and Clean Energy Investment Forum renewable energy technologies in the country. Informing Energy Access and Clean Energy Project Finance understanding and knowledge of how to design policies that enable financing and encourage investment in clean

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.

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

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

Modelling the structure factors and pair distribution functions of amorphous germanium, silicon and carbon

International Nuclear Information System (INIS)

Dalgic, Seyfettin; Gonzalez, Luis Enrique; Baer, Shalom; Silbert, Moises

2002-01-01

We present the results of calculations of the static structure factor S(k) and the pair distribution function g(r) of the tetrahedral amorphous semiconductors germanium, silicon and carbon using the structural diffusion model (SDM). The results obtained with the SDM for S(k) and g(r) are of comparable quality with those obtained by the unconstrained Reverse Monte Carlo simulations and existing ab initio molecular dynamics simulations for these systems. We have found that g(r) exhibits a small peak, or shoulder, a weak remnant of the prominent third neighbour peak present in the crystalline phase of these systems. This feature has been experimentally found to be present in recently reported high energy X-ray experiments of amorphous silicon (Phys. Rev. B 60 (1999) 13520), as well as in the previous X-ray diffraction of as-evaporated amorphous germanium (Phys. Rev. B 50 (1994) 539)

Modelling the structure factors and pair distribution functions of amorphous germanium, silicon and carbon

Energy Technology Data Exchange (ETDEWEB)

Dalgic, Seyfettin; Gonzalez, Luis Enrique; Baer, Shalom; Silbert, Moises

2002-12-01

We present the results of calculations of the static structure factor S(k) and the pair distribution function g(r) of the tetrahedral amorphous semiconductors germanium, silicon and carbon using the structural diffusion model (SDM). The results obtained with the SDM for S(k) and g(r) are of comparable quality with those obtained by the unconstrained Reverse Monte Carlo simulations and existing ab initio molecular dynamics simulations for these systems. We have found that g(r) exhibits a small peak, or shoulder, a weak remnant of the prominent third neighbour peak present in the crystalline phase of these systems. This feature has been experimentally found to be present in recently reported high energy X-ray experiments of amorphous silicon (Phys. Rev. B 60 (1999) 13520), as well as in the previous X-ray diffraction of as-evaporated amorphous germanium (Phys. Rev. B 50 (1994) 539)

Synthesis, structure, and thermal properties of soluble hydrazinium germanium(IV) and tin(IV) selenide salts.

Science.gov (United States)

Mitzi, David B

2005-05-16

The crystal structures of two hydrazinium-based germanium(IV) and tin(IV) selenide salts are determined. (N(2)H(5))(4)Ge(2)Se(6) (1) [I4(1)cd, a = 12.708(1) Angstroms, c = 21.955(2) Angstroms, Z = 8] and (N(2)H(4))(3)(N(2)H(5))(4)Sn(2)Se(6) (2) [P, a = 6.6475(6) Angstroms, b = 9.5474(9) Angstroms, c = 9.8830(10) Angstroms, alpha = 94.110(2) degrees, beta = 99.429(2) degrees, gamma = 104.141(2) degrees, Z = 1] each consist of anionic dimers of edge-sharing metal selenide tetrahedra, M(2)Se(6)(4-) (M = Ge or Sn), separated by hydrazinium cations and, for 2, additional neutral hydrazine molecules. Substantial hydrogen bonding exists among the hydrazine/hydrazinium molecules as well as between the hydrazinium cations and the selenide anions. Whereas the previously reported tin(IV) sulfide system, (N(2)H(5))(4)Sn(2)S(6), decomposes cleanly to microcrystalline SnS(2) when heated to 200 degrees C in an inert atmosphere, higher temperatures (>300 degrees C) are required to dissociate selenium from 1 and 2 for the analogous preparations of single-phase metal selenides. The metal chalcogenide salts are highly soluble in hydrazine, as well as in a variety of amines and DMSO, highlighting the potential usefulness of these compounds as precursors for the solution deposition of the corresponding metal chalcogenide films.

TIGRESS highly-segmented high-purity germanium clover detector

Science.gov (United States)

Scraggs, H. C.; Pearson, C. J.; Hackman, G.; Smith, M. B.; Austin, R. A. E.; Ball, G. C.; Boston, A. J.; Bricault, P.; Chakrawarthy, R. S.; Churchman, R.; Cowan, N.; Cronkhite, G.; Cunningham, E. S.; Drake, T. E.; Finlay, P.; Garrett, P. E.; Grinyer, G. F.; Hyland, B.; Jones, B.; Leslie, J. R.; Martin, J.-P.; Morris, D.; Morton, A. C.; Phillips, A. A.; Sarazin, F.; Schumaker, M. A.; Svensson, C. E.; Valiente-Dobón, J. J.; Waddington, J. C.; Watters, L. M.; Zimmerman, L.

2005-05-01

The TRIUMF-ISAC Gamma-Ray Escape-Suppressed Spectrometer (TIGRESS) will consist of twelve units of four high-purity germanium (HPGe) crystals in a common cryostat. The outer contacts of each crystal will be divided into four quadrants and two lateral segments for a total of eight outer contacts. The performance of a prototype HPGe four-crystal unit has been investigated. Integrated noise spectra for all contacts were measured. Energy resolutions, relative efficiencies for both individual crystals and for the entire unit, and peak-to-total ratios were measured with point-like sources. Position-dependent performance was measured by moving a collimated source across the face of the detector.

Efficient methods of nanoimprint stamp cleaning based on imprint self-cleaning effect

Energy Technology Data Exchange (ETDEWEB)

Meng Fantao; Chu Jinkui [Key Laboratory for Micro/Nano Technology and System of Liaoning Province, Dalian University of Technology, 116024 Dalian (China); Luo Gang; Zhou Ye; Carlberg, Patrick; Heidari, Babak [Obducat AB, SE-20125 Malmoe (Sweden); Maximov, Ivan; Montelius, Lars; Xu, H Q [Division of Solid State Physics, Lund University, Box 118, S-22100 Lund (Sweden); Nilsson, Lars, E-mail: ivan.maximov@ftf.lth.se [Department of Food Technology, Engineering and Nutrition, Lund University, Box 117, S-22100 Lund (Sweden)

2011-05-06

Nanoimprint lithography (NIL) is a nonconventional lithographic technique that promises low-cost, high-throughput patterning of structures with sub-10 nm resolution. Contamination of nanoimprint stamps is one of the key obstacles to industrialize the NIL technology. Here, we report two efficient approaches for removal of typical contamination of particles and residual resist from stamps: thermal and ultraviolet (UV) imprinting cleaning-both based on the self-cleaning effect of imprinting process. The contaminated stamps were imprinted onto polymer substrates and after demolding, they were treated with an organic solvent. The images of the stamp before and after the cleaning processes show that the two cleaning approaches can effectively remove contamination from stamps without destroying the stamp structures. The contact angles of the stamp before and after the cleaning processes indicate that the cleaning methods do not significantly degrade the anti-sticking layer. The cleaning processes reported in this work could also be used for substrate cleaning.

How clean is clean?---How clean is needed?

International Nuclear Information System (INIS)

Hays, A.K.

1991-01-01

This paper will provide an overview of cleaning qualifications used in a variety of industries: from small-scale manufacturer's of precision-machined products to large-scale manufacturer's of electronics (printed wiring boards and surface mount technology) and microelectronics. Cleanliness testing techniques used in the production of precision-machined products, will be described. The on-going DOD program to obtain high-reliability electronics, through the use of military specifications for cleaning and cleanliness levels, will be reviewed. In addition, the continually changing cleanroom/materials standards of the microelectronics industry will be discussed. Finally, we will speculate on the role that new and improved analytical techniques and sensor technologies will play in the factories of the future. 4 refs., 1 tab

Bioavailable concentrations of germanium and rare earth elements in soil as affected by low molecular weight organic acids and root exudates

Science.gov (United States)

Wiche, Oliver; Székely, Balázs; Kummer, Nicolai-Alexeji; Heinemann, Ute; Tesch, Silke; Heilmeier, Hermann

2014-05-01

Availability of elements in soil to plant is generally dependent on the solubility and mobility of elements in soil solution which is controlled by soil, elemental properties and plant-soil interactions. Low molecular organic acids or other root exudates may increase mobility and availability of certain elements for plants as an effect of lowering pH in the rhizosphere and complexation. However, these processes take place in a larger volume in soil, therefore to understand their nature, it is also important to know in which layers of the soil what factors modify these processes. In this work the influence of citric acid and root exudates of white lupin (Lupinus albus L.) on bioavailable concentrations of germanium, lanthan, neodymium, gadolinium and erbium in soil solution and uptake in root and shoot of rape (Brassica napus L.), comfrey (Symphytum officinale L.), common millet (Panicum milliaceum L.) and oat (Avena sativa L.) was investigated. Two different pot experiments were conducted: (1) the mentioned plant species were treated with nutrient solutions containing various amount of citric acid; (2) white lupin was cultivated in mixed culture (0 % lupin, 33 % lupin) with oat (Avena sativa L.) and soil solution was obtained by plastic suction cups placed at various depths. As a result, addition of citric acid significantly increased germanium concentrations in plant tissue of comfrey and rape and increased translocation of germanium, lanthan, neodymium, gadolinium and erbium from root to shoot. The cultivation of white lupin in mixed culture with oat led to significantly higher concentrations of germanium and increasing concentrations of lanthan, neodymium, gadolinium and erbium in soil solution and aboveground plant tissue. In these pots concentrations of citric acid in soil solution were significantly higher than in the control. The results show, that low molecular organic acids exuded by plant roots are of great importance for the mobilization of germanium

From stellar plasmas to laboratory plasmas: application to X and XUV opacity measurements

International Nuclear Information System (INIS)

Loisel, G.

2011-01-01

The general context of this thesis is the one of radiative properties of high energy density matter. Energy densities involved (>10 11 J/cm 3 ) implies that a large part of energy exchange goes through radiation-matter interactions. My studies deal with spectral opacity, a fundamental parameter for modelling stellar interiors and constitute a propitious observable to experimental tests of theoretical descriptions of hot and dense plasmas physics. Although the main application of my work is stellar plasmas it can be useful for plasma diagnostics in inertial confinement fusion. My work activities are centred on the experimental study of opacities of plasmas at local thermodynamic equilibrium for temperature conditions of a few tens eV (a few 100000 K) and a few mg/cm 3 in matter density. Plasmas are obtained in conditions as homogenous as possible using the radiative heating of a laser-irradiated cavity. Heating is provided through a laser beam of high energy (100-300 J) and with relatively long pulse duration of a few nanosecond. For such measurements we could benefit from the LULI lasers configuration coupling the nanosecond beam with a picosecond one used to perform on a short duration the measurement of the plasma transmission. The use of short pulse laser to produce a short time radiography beam was a first achievement for this kind of experience. In the spectral range of keV photons, absorbing transitions 2p-3d or 3d-4f of elements of moderate or high atomic number have been probed. They present absorption structures which shape results mainly of the competition between spin-orbit splitting and statistical broadening effects. It appeared that this competition depends strongly on the atomic number Z. Thus for similar plasma parameters we explored opacities of Iron, Nickel, Copper and Germanium (Z around 30) in a first series of measurement and the one of Barium, Samarium and Gadolinium (Z around 60) in a second campaign

Thickness, Doping Accuracy, and Roughness Control in Graded Germanium Doped Ch{sub x} Micro-shells for Lmj

Energy Technology Data Exchange (ETDEWEB)

Legay, G.; Theobald, M.; Barnouin, J.; Peche, E.; Bednarczyk, S.; Hermerel, C. [CEA Valduc, Dept Rech Mat Nucl, Serv Microcibles, 21 - Is-sur-Tille (France)

2009-05-15

In the Commissariat a l'Energie Atomique Laser Megajoule (LMJ) facility, amorphous hydrogenated carbon (a-C: H or CH{sub x}) is the nominal ablator used to achieve inertial confinement fusion experiments. These targets are filled with of fusible mixture of deuterium-tritium in order to perform ignition. The a-C: H shell is deposited on a poly-alpha-methylstyrene (PAMS) mandrel by glow discharge polymerization with trans-2-butene, hydrogen, and helium. Graded germanium doped CH{sub x} micro-shells are supposed to be more stable regarding hydrodynamic instabilities. The shells are composed of four layers for a total thickness of 180 {mu}m. The germanium gradient is obtained by doping the different a-C: H layers with the addition of tetra-methylgermanium in the gas mixture. As the achievement of ignition greatly depends on the physical properties of the shell, the thicknesses, doping concentration, and roughness must be precisely controlled. Quartz microbalances were used to perform an in situ and real-time measurement of the thickness in order to reduce the variations and so our fabrication tolerances on each layer thickness. Ex situ control of the thickness of each layer was carried out, with both optical coherent tomography and interferometry, (wall-mapper). High-quality, PAMS and a rolling system have been used to lower the low-mode roughness [root-mean-square (rms) (mode 2) {<=} 70 nm]. High modes were clearly, reduced by, coating the pan containing the shells with polyvinyl alcohol + CH{sub x} instead of polystyrene + CH{sub x} resulting in an rms ({>=}mode 10) {<=} 20 nm, which can be {<=}15 nm for the best micro-shells. The germanium concentration (0. 4 and 0. 75 at. %) in the a-CH layer is obtained by regulating the tetramethyl-germanium flow. Low range mass flow controllers have been used to improve the doping accuracy. (authors)

Advanced characterization of carrier profiles in germanium using micro-machined contact probes

DEFF Research Database (Denmark)

Clarysse, T.; Konttinen, M.; Parmentier, B.

2012-01-01

of new concepts based on micro machined, closely spaced contact probes (10 μm pitch). When using four probes to perform sheet resistance measurements, a quantitative carrier profile extraction based on the evolution of the sheet resistance versus depth along a beveled surface is obtained. Considering...... the properties of both approaches on Al+ implants in germanium with different anneal treatments....

Calibration curve for germanium spectrometers from solutions calibrated by liquid scintillation counting

International Nuclear Information System (INIS)

Grau, A.; Navarro, N.; Rodriguez, L.; Alvarez, A.; Salvador, S.; Diaz, C.

1996-01-01

The beta-gamma emitters ''60Co, ''137 Cs, ''131 I, ''210 Pb y ''129 Iare radionuclides for which the calibration by the CIEMAT/NIST method ispossible with uncertainties less than 1%. We prepared, from standardized solutions of these radionuclides, samples in vials of 20 ml. We obtained the calibration curves, efficiency as a function of energy, for two germanium detectors. (Author) 5 refs

Formation probabilities and relaxation rates of muon states in germanium

International Nuclear Information System (INIS)

Clawson, C.W.; Haller, E.E.; Crowe, K.M.; Rosenblum, S.S.; Brewer, J.H.; British Columbia Univ., Vancouver

1981-01-01

We report the first results of a study of the muonium states in ultra-pure germanium crystals grown under a variety of conditions at Lawrence Berkeley Laboratory. Among the variations studied are: 1) Hydrogen, deuterium, or nitrogen atmosphere during growth; 2) Dislocation-free vs. dislocated crystals; 3) Grown from quartz, graphite, and pyrolytic graphite coated quartz crucibles; 4) n-type vs. p-type. We report a significant difference in the muonium relaxation rate between the dislocated and non-dislocated crystals. (orig.)

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.

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

Grafting of Oligo(ethylene glycol) Functionalized Calix[4]arene-tetra-diazonium Salts for Antifouling Germanium and Gold Surfaces.

Science.gov (United States)

Blond, Pascale; Mattiuzzi, Alice; Valkenier, Hennie; Troian-Gautier, Ludovic; Bergamini, Jean-François; Doneux, Thomas; Goormaghtigh, Erik; Raussens, Vincent; Jabin, Ivan

2018-05-03

Biosensors that can determine protein concentration and structure are highly desired for biomedical applications. For the development of such biosensors, the use of Fourier transformed infra-red (FTIR) spectroscopy with the attenuated internal total reflection (ATR) configuration is particularly attractive but it requires appropriate surface functionalization of the ATR optical element. Indeed, the surface has to specifically interact with a target protein in close contact with the optical element and must display antifouling properties to prevent nonspecific adsorption of other proteins. We here report robust monolayers of calix[4]arenes bearing oEGs chains, which were grafted on germanium and gold surfaces via their tetra-diazonium salts. The formation of monolayers of oEGylated calix[4]arenes was confirmed by AFM, IR and contact angle measurements. The antifouling properties of these modified surfaces were studied by ATR-FTIR spectroscopy and fluorescence microscopy and the non-specific absorption of BSA was found to be reduced by 85% compared to non-modified germanium. In other words, the organic coating by oEGylated calix[4]arenes provides remarkable antifouling properties, opening the way to the design of germanium- and gold-based biosensors.

Irradiation induced defects containing oxygen atoms in germanium crystal as studied by deep level transient spectroscopy

International Nuclear Information System (INIS)

Fukuoka, Noboru; Kambe, Yoshiyuki; Saito, Haruo; Matsuda, Koji.

1984-05-01

Deep level transient spectroscopy was applied to the electron trapping levels which are associated with the irradiation induced lattice defects in germanium crystals. The germanium crystals used in the study were doped with oxygen, antimony or arsenic and the defects were formed by electron irradiation of 1.5MeV or 10MeV. The nature of so called ''thermal defect'' formed by heat treatment at about 670K was also studied. The trapping levels at Esub(c)-0.13eV, Esub(c)-0.25eV and Esub(c)-0.29eV were found to be associated with defects containing oxygen atoms. From the experimental results the Esub(c)-0.25eV level was attributed to the germanium A-center (interstitial oxygen atom-vacancy pair). Another defect associated with the 715cm -1 infrared absorption band was found to have a trapping level at the same position at Esub(c)-0.25eV. The Esub(c)-0.23eV and Esub(c)-0.1eV levels were revealed to be associated with thermal donors formed by heat treatment at about 670K. Additional two peaks (levels) were observed in the DLTS spectrum. The annealing behavior of the levels suggests that the thermal donors originate from not a single type but several types of defects. (author)

Evaluation of concepts for a NET plasma exhaust clean-up system

International Nuclear Information System (INIS)

Glugla, M.; Penzhorn, R.D.; Rodriguez, R.; Herbrechter, D.; Dinner, P.; Murdoch, D.

1990-07-01

The process steps for the off-gas clean-up and direct recovery of the unburned fuel gases deuterium and tritium are, together with the isotope separation and the fuel preparation, the major subsystems within the fuel cycle of a fusion reactor. A comparison between process concepts largely based on experimental work at KfK and other process alternatives discussed in the literature is carried out and the various options are evaluated on the basis of the process requirements for NET I. The recovery of most of the unburned hydrogen with a palladium/silver permeator is selected as a first step, common to all seven concepts. The remaining impurity stream is processed either catalytically, with the help of getters, or by oxidation followed by reduction of the produced water. The physicochemical basis of each process alternative is discussed and the corresponding chemical flow sheets (flow diagrams and material flow tables) are presented. Concepts employing getters are unattractive because the produce untolerably high amounts of solid waste. Main drawbacks of process options involving an oxidation step are the non-discriminative oxidation of hydrogen and impurities as well as the non-trivial reduction of the produced highly tritiated water at the required elevated throughput. Advantages of the catalytic process are the production of little solid waste, the low steady state inventory and the comparatively easy scale-up. The catalytic process is therefore considered the most promising option for the development of a fuel clean-up process. (orig./HK) [de

The influence of impurity and particle control on TMX-U [Tandem Mirror Experiment Upgrade] plasma operation

International Nuclear Information System (INIS)

Allen, S.L.; Yu, T.L.; Foote, J.H.; Pickles, W.L.

1985-11-01

A variety of techniques are used in TMX-U to control impurities and reflux: repeated plasma pulses, glow discharge cleaning (GDC), and gettering. A series of experiments under three different plasma-wall conditions was performed: no wall conditioning after a machine maintenance cycle, a glow-discharge-cleaned wall, and a gettered wall. Several plasma diagnostics to determine the effect of these procedures on TMX-U plasma parameters were used. Spectroscopic measurements indicated that GDC reduced impurities and increased the electron temperature, enabling full-duration beam-sustained plasma operation without a large number of repeated plasma pulses. Gettering further reduced the impurities and the neutral pressure, and this improved condition persisted for several shots after gettering was stopped. Measurements from residual gas analyzers and an end-loss ion spectrometer indicated that hydrogen is present in the plasma during the initial deuterium operation after pumpdown; the hydrogen level decreased after plasma operation with gettering, indicating reduced wall recycling

Effect of germanium concentrations on tunnelling current calculation of Si/Si1-xGex/Si heterojunction bipolar transistor

Science.gov (United States)

Hasanah, L.; Suhendi, E.; Khairrurijal

2018-05-01

Tunelling current calculation on Si/Si1-xGex/Si heterojunction bipolar transistor was carried out by including the coupling between transversal and longitudinal components of electron motion. The calculation results indicated that the coupling between kinetic energy in parallel and perpendicular to S1-xGex barrier surface affected tunneling current significantly when electron velocity was faster than 1x105 m/s. This analytical tunneling current model was then used to study how the germanium concentration in base to Si/Si1-xGex/Si heterojunction bipolar transistor influenced the tunneling current. It is obtained that tunneling current increased as the germanium concentration given in base decreased.

Measurement of the quantum conductance of germanium by an electrochemical scanning tunneling microscope break junction based on a jump-to-contact mechanism.

Science.gov (United States)

Xie, Xufen; Yan, Jiawei; Liang, Jinghong; Li, Jijun; Zhang, Meng; Mao, Bingwei

2013-10-01

We present quantum conductance measurements of germanium by means of an electrochemical scanning tunneling microscope (STM) break junction based on a jump-to-contact mechanism. Germanium nanowires between a platinum/iridium tip and different substrates were constructed to measure the quantum conductance. By applying appropriate potentials to the substrate and the tip, the process of heterogeneous contact and homogeneous breakage was realized. Typical conductance traces exhibit steps at 0.025 and 0.05 G0. The conductance histogram indicates that the conductance of germanium nanowires is located between 0.02 and 0.15 G0 in the low-conductance region and is free from the influence of substrate materials. However, the distribution of conductance plateaus is too discrete to display distinct peaks in the conductance histogram of the high-conductance region. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Plasma state. The universe's fire

International Nuclear Information System (INIS)

Lehner, Th.

2004-01-01

The plasma is the fourth state of matter, obtained at a very high temperature by the separation of the electrons from their nuclei. Plasma represents 99% of the visible mass of our present day universe and was the unique state of matter at its very beginning. Plasmas are present in the core of stars and in the interstellar environment. More closer to us, they are responsible of spectacular phenomena, like aurora borealis, lightning, comet queues etc.. This book makes a review of the different types of plasmas (electromagnetic, Earth's plasmas, spatial plasmas, solar plasmas, astrophysical plasmas). One chapter presents the thermonuclear fusion as future energy source. Another one treats of the chaos and turbulence inside plasmas. Some applications of plasmas are reviewed: MHD and ionic propulsion systems, MHD energy conversion and MHD generators, thermo-ionic converters, solid-state plasmas, particle accelerators, coherent radiation sources, 'Zeta' machines, X-ray lasers, isotopic separation, non-neutral plasmas and charged beams, free-electrons lasers, electrons and positrons plasmas, industrial applications (etching and cleaning, manufacturing of solar cells, flat screens, industrial reactors, waste treatment, cold plasma-assisted sterilization, effluents decontamination etc.). A last chapter makes an overview of the modern research in plasma physics. (J.S.)

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.

X-ray spectroscopy of warm and hot electron components in the CAPRICE source plasma at EIS testbench at GSI.

Science.gov (United States)

Mascali, D; Celona, L; Maimone, F; Maeder, J; Castro, G; Romano, F P; Musumarra, A; Altana, C; Caliri, C; Torrisi, G; Neri, L; Gammino, S; Tinschert, K; Spaedtke, K P; Rossbach, J; Lang, R; Ciavola, G

2014-02-01

An experimental campaign aiming to detect X radiation emitted by the plasma of the CAPRICE source - operating at GSI, Darmstadt - has been carried out. Two different detectors (a SDD - Silicon Drift Detector and a HpGe - hyper-pure Germanium detector) have been used to characterize the warm (2-30 keV) and hot (30-500 keV) electrons in the plasma, collecting the emission intensity and the energy spectra for different pumping wave frequencies and then correlating them with the CSD of the extracted beam measured by means of a bending magnet. A plasma emissivity model has been used to extract the plasma density along the cone of sight of the SDD and HpGe detectors, which have been placed beyond specific collimators developed on purpose. Results show that the tuning of the pumping frequency considerably modifies the plasma density especially in the warm electron population domain, which is the component responsible for ionization processes: a strong variation of the plasma density near axis region has been detected. Potential correlations with the charge state distribution in the plasma are explored.

Electron cyclotron resonance ion source plasma characterization by X-ray spectroscopy and X-ray imaging

Energy Technology Data Exchange (ETDEWEB)

Mascali, David, E-mail: davidmascali@lns.infn.it; Castro, Giuseppe; Celona, Luigi; Neri, Lorenzo; Gammino, Santo [INFN–Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); Biri, Sándor; Rácz, Richárd; Pálinkás, József [Institute for Nuclear Research (Atomki), Hungarian Academy of Sciences, Bem tér 18/c, H-4026 Debrecen (Hungary); Caliri, Claudia [INFN–Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); Università degli Studi di Catania, Dip.to di Fisica e Astronomia, via Santa Sofia 64, 95123 Catania (Italy); Romano, Francesco Paolo [INFN–Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); CNR, Istituto per i Beni Archeologici e Monumentali, Via Biblioteca 4, 95124 Catania (Italy); Torrisi, Giuseppe [INFN–Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); Università Mediterranea di Reggio Calabria, DIIES, Via Graziella, I-89100 Reggio Calabria (Italy)

2016-02-15

An experimental campaign aiming to investigate electron cyclotron resonance (ECR) plasma X-ray emission has been recently carried out at the ECRISs—Electron Cyclotron Resonance Ion Sources laboratory of Atomki based on a collaboration between the Debrecen and Catania ECR teams. In a first series, the X-ray spectroscopy was performed through silicon drift detectors and high purity germanium detectors, characterizing the volumetric plasma emission. The on-purpose developed collimation system was suitable for direct plasma density evaluation, performed “on-line” during beam extraction and charge state distribution characterization. A campaign for correlating the plasma density and temperature with the output charge states and the beam intensity for different pumping wave frequencies, different magnetic field profiles, and single-gas/gas-mixing configurations was carried out. The results reveal a surprisingly very good agreement between warm-electron density fluctuations, output beam currents, and the calculated electromagnetic modal density of the plasma chamber. A charge-coupled device camera coupled to a small pin-hole allowing X-ray imaging was installed and numerous X-ray photos were taken in order to study the peculiarities of the ECRIS plasma structure.

Clean data

CERN Document Server

Squire, Megan

2015-01-01

If you are a data scientist of any level, beginners included, and interested in cleaning up your data, this is the book for you! Experience with Python or PHP is assumed, but no previous knowledge of data cleaning is needed.

Establishing reliable good initial quantum efficiency and in-situ laser cleaning for the copper cathodes in the RF gun

Energy Technology Data Exchange (ETDEWEB)

Zhou, F., E-mail: zhoufeng@slac.stanford.edu; Sheppard, J.C.; Vecchione, T.; Jongewaard, E.; Brachmann, A.; Corbett, J.; Gilevich, S.; Weathersby, S.

2015-05-21

Establishing good initial quantum efficiency (QE) and reliable in-situ cleaning for copper cathode in the RF gun is of critical importance for the RF gun operations. Recent studies on the SLAC RF gun test bed indicated that the pre-cleaning (plasma cleaning) in the test chamber followed by copper cathode exposure to air for cathode change leads to a very low initial QE in the RF gun, and also demonstrated that without the pre-cleaning good initial QE >4×10{sup −5} can be routinely achieved in the RF gun with the cathodes of QE <1×10{sup −7} measured in the test chamber. QE can decay over the time in the RF gun. The in-situ laser cleaning technique for copper cathodes in the RF gun is established and refined in comparison to previous cleaning at the linac coherent light source, resulting in an improved QE and emittance evolutions. The physics of the laser cleaning process is discussed. It is believed that the reflectivity change is one of the major factors for the QE boost with the laser cleaning.

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

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

Characteristic of the immunological state of Chernobyl accident clean-up workers in a late period after the accident

International Nuclear Information System (INIS)

Kurjane, N.; Zvagule, T.; Curbakova, E.; Bruvere, R.; Romanova, T.; Sitova, O; Hagina, E.; Socnevs, A.

2001-01-01

No differences in the number of immunologically competent cells and other immunological variables were found among the clean-up workers, depending on the time they were in Chernobyl. However, a statistically significant reduction in the number of CD3+, CD4+, CD16+ and CD19+, decrease in the levels of IgG and suppression of APH and the phagocytic activity of neutrophils with a simultaneous increase in the levels of IgA and C3d was found in all clean-up workers when compared to controls. In a small group of clean-up workers, the levels of some plasma cytokines were detected. A statistically significant increase in IL-6 levels was found in the clean-up workers when compared to controls. The irradiation received by the Chernobyl accident clean-up workers was large enough to cause disturbances in the function of cells and organ systems through immune system disorders with a resultant weakening of the body response and adaptation mechanisms. (authors)

High-resolution clean-sc

NARCIS (Netherlands)

Sijtsma, P.; Snellen, M.

2016-01-01

In this paper a high-resolution extension of CLEAN-SC is proposed: HR-CLEAN-SC. Where CLEAN-SC uses peak sources in “dirty maps” to define so-called source components, HR-CLEAN-SC takes advantage of the fact that source components can likewise be derived from points at some distance from the peak,

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-}.

Atmospheric-pressure plasma jet

Science.gov (United States)

Selwyn, Gary S.

1999-01-01

Atmospheric-pressure plasma jet. A .gamma.-mode, resonant-cavity plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two concentric cylindrical electrodes are employed to generate a plasma in the annular region therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly shaping the rf-powered electrode. Because of the atmospheric pressure operation, no ions survive for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike low-pressure plasma sources and conventional plasma processing methods.

Fabrication and research of high purity germanium detectors with abrupt and thin diffusion layer

International Nuclear Information System (INIS)

Rodriguez Cabal, A. E.; Diaz Garcia, A.

1997-01-01

A different high purity germanium detector's fabrication method is described. A very thin diffusion film with an abrupt change of the type of conductivity is obtained. The fine diffusion layer thickness makes possibly their utilization in experimental systems in which all the data are elaborated directly on the computer. (author) [es

Microwave plasma synthesis of Si/Ge and Si/WSi2 nanoparticles for thermoelectric applications

Science.gov (United States)

Petermann, Nils; Schneider, Tom; Stötzel, Julia; Stein, Niklas; Weise, Claudia; Wlokas, Irenäus; Schierning, Gabi; Wiggers, Hartmut

2015-08-01

The utilization of microwave-based plasma systems enables a contamination-free synthesis of highly specific nanoparticles in the gas phase. A reactor setup allowing stable, long-term operation was developed with the support of computational fluid dynamics. This paper highlights the prospects of gas-phase plasma synthesis to produce specific materials for bulk thermoelectrics. Taking advantage of specific plasma reactor properties such as Coulomb repulsion in combination with gas temperatures considerably higher than 1000 K, spherical and non-aggregated nanoparticles of multiple compositions are accessible. Different strategies towards various nanostructured composites and alloys are discussed. It is shown that, based on doped silicon/germanium alloys and composites, thermoelectric materials with zT values up to almost unity can be synthesized in one step. First experimental results concerning silicon/tungsten silicide thermoelectrics applying the nanoparticle-in-alloy idea are presented indicating that this concept might work. However, it is found that tungsten silicides show a surprising sinter activity more than 1000 K below their melting temperature.

Quantitative spectrographic determination of traces of germanium in lignite; Determinacion Espectrografica Cuantitativa de trazas de Germanio en Lignitos

Energy Technology Data Exchange (ETDEWEB)

Martin, M; Roca, M

1972-07-01

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{sub 2}SO{sub 4}, CuF{sub 2}, Sb{sub 2}S{sub 3} and Bi{sub 2}S{sub 3} have been tested as sweeping materials. Using 2% CuF{sub 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.

Controlling the clean room atmosphere

International Nuclear Information System (INIS)

Meeks, R.F.

1979-01-01

Several types of clean rooms are commonly in use. They include the conventional clean room, the horizontal laminar flow clean room, the vertical laminar flow clean room and a fourth type that incorporates ideas from the previous types and is known as a clean air bench or hood. These clean rooms are briefly described. The origin of contamination and methods for controlling the contamination are discussed

Photoresist removal using gaseous sulfur trioxide cleaning technology

Science.gov (United States)

Del Puppo, Helene; Bocian, Paul B.; Waleh, Ahmad

1999-06-01

A novel cleaning method for removing photoresists and organic polymers from semiconductor wafers is described. This non-plasma method uses anhydrous sulfur trioxide gas in a two-step process, during which, the substrate is first exposed to SO3 vapor at relatively low temperatures and then is rinsed with de-ionized water. The process is radically different from conventional plasma-ashing methods in that the photoresist is not etched or removed during the exposure to SO3. Rather, the removal of the modified photoresist takes place during the subsequent DI-water rinse step. The SO3 process completely removes photoresist and polymer residues in many post-etch applications. Additional advantages of the process are absence of halogen gases and elimination of the need for other solvents and wet chemicals. The process also enjoys a very low cost of ownership and has minimal environmental impact. The SEM and SIMS surface analysis results are presented to show the effectiveness of gaseous SO3 process after polysilicon, metal an oxide etch applications. The effects of both chlorine- and fluorine-based plasma chemistries on resist removal are described.

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

Surface studies of plasma processed Nb samples

International Nuclear Information System (INIS)

Tyagi, Puneet V.; Doleans, Marc; Hannah, Brian S.; Afanador, Ralph; Stewart, Stephen; Mammosser, John; Howell, Matthew P; Saunders, Jeffrey W; Degraff, Brian D; Kim, Sang-Ho

2015-01-01

Contaminants present at top surface of superconducting radio frequency (SRF) cavities can act as field emitters and restrict the cavity accelerating gradient. A room temperature in-situ plasma processing technology for SRF cavities aiming to clean hydrocarbons from inner surface of cavities has been recently developed at the Spallation Neutron Source (SNS). Surface studies of the plasma-processed Nb samples by Secondary ion mass spectrometry (SIMS) and Scanning Kelvin Probe (SKP) showed that the NeO_2 plasma processing is very effective to remove carbonaceous contaminants from top surface and improves the surface work function by 0.5 to 1.0 eV.

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

Over the past 10 years, increased interest in the supply security of metal and mineral raw materials has resulted in the compilation of many lists of materials of particular concern. These materials are generally referred to as 'critical'. They are perceived to be both of high economic importance, as well as subject to high supply risks. Of particular relevance with respect to supply risk is the assessment of geological risk factors. However, this aspect is not considered in sufficient detail in most studies. In particular, the specific features of elements won as by-products are not adequately represented in any assessment. Yet many of these elements are often classified as critical, mostly due to their apparent importance in high-tech applications, the intransparency of their respective markets and resulting price volatility, and the concentration of their production in China. Gallium, germanium and indium are all good examples of such elements. All three are similar in many respects, and commonly have a similar rating in both the economic importance and supply risk dimensions. The aim of this work was to use these three elements as examples, and investigate whether they are truly as similar as current assessments suggest, or whether there are large underlying differences in their specific supply situations. In particular, the focus was on physical supply limitations: Since by-products can only be extracted with other main-product raw materials, their rate of extraction is limited by the extraction rate of these main products. This means that the relevant quantities for an assessment of their physical supply limitations are not reserves and/or resources, but supply potentials. The supply potential is the quantity of a given by-product which could theoretically be extracted under current market conditions (price, technology) per year if all suitable raw materials were processed accordingly. To assess the supply potentials of gallium, germanium and indium

Characteristic features of the behaviour of deep centers in especially pure germanium

International Nuclear Information System (INIS)

Gloriozova, R.I.; Kolesnik, L.I.

1993-01-01

Method of capacitive relaxation spectroscopy was used to study spectrum of deep centers in germanium crystals of p-type conductivity with 10 11 -10 13 cm -3 charge carrier concentration, depending on dislocation density and thermal treatment. Existence of two types of centers with 0.24 and 0.32 eV ionization energies, dictating the maximum near 140 K, was established. Change of deep center concentration with time was revealed

Investigation of some cleaning surface treatments for the fabrication of ITER first wall panels by HIP

Energy Technology Data Exchange (ETDEWEB)

Frayssines, P.E.; Bucci, P. [CEA Grenoble (DRT/LITEN/DTH), 38 (France); Vito, E. de [CEA Grenoble (LITEN/DTH/LCPEM), 38 (France); Lorenzetto, P. [2EFDA, Garching (Germany)

2007-07-01

Full text of publication follows: ITER First Wall (FW) panels are the innermost part of the ITER reactor. Metallic materials used for their manufacture are 316L(N)-IG stainless steel, a copper alloy and beryllium. Stainless steel material is a support structure for the copper alloy that serves as a heat sink material and also for the beryllium tiles that are a protective armour against the plasma. All these materials are bonded together by Hot Isostatic Pressing (HIP). Thus, several types of joints (Cu/Cu, Cu/SS, SS/SS or Cu/Be) are present in a FW panels. Their manufacturing requires a very strict and advanced metallic surface preparation in order to eliminate most of the organic or oxide layers that could prevent the diffusion process between the facing materials. In this field, our laboratory practice enables to obtain sufficiently clean metallic surfaces and high strength joints are obtained when small mockups are made. However, the manufacture of a large number of FW panels in the future requires to find a new cleaning process that is industrially relevant without a strong reduction of the joint's mechanical properties. In this paper we present our investigations to find an industrial solution to clean efficiently copper alloy and stainless steel materials in order to manufacture high strength Cu/Cu, SS/SS or Cu/SS joints. Products investigated are mainly acid liquids proposed by chemical Company and a more advanced technique that uses a plasma process. HIP joints are tested mechanically by making impact toughness and tensile measurements. Results obtained with these solutions are compared to those obtained in our Laboratory by using our own cleaning route. Moreover, XPS analyses are performed on small specimens that have been submitted to the same cleaning treatments in order to better understand the mechanical results of our specimens. (authors)

Investigation of some cleaning surface treatments for the fabrication of ITER first wall panels by HIP

International Nuclear Information System (INIS)

Frayssines, P.E.; Bucci, P.; Vito, E. de; Lorenzetto, P.

2007-01-01

Full text of publication follows: ITER First Wall (FW) panels are the innermost part of the ITER reactor. Metallic materials used for their manufacture are 316L(N)-IG stainless steel, a copper alloy and beryllium. Stainless steel material is a support structure for the copper alloy that serves as a heat sink material and also for the beryllium tiles that are a protective armour against the plasma. All these materials are bonded together by Hot Isostatic Pressing (HIP). Thus, several types of joints (Cu/Cu, Cu/SS, SS/SS or Cu/Be) are present in a FW panels. Their manufacturing requires a very strict and advanced metallic surface preparation in order to eliminate most of the organic or oxide layers that could prevent the diffusion process between the facing materials. In this field, our laboratory practice enables to obtain sufficiently clean metallic surfaces and high strength joints are obtained when small mockups are made. However, the manufacture of a large number of FW panels in the future requires to find a new cleaning process that is industrially relevant without a strong reduction of the joint's mechanical properties. In this paper we present our investigations to find an industrial solution to clean efficiently copper alloy and stainless steel materials in order to manufacture high strength Cu/Cu, SS/SS or Cu/SS joints. Products investigated are mainly acid liquids proposed by chemical Company and a more advanced technique that uses a plasma process. HIP joints are tested mechanically by making impact toughness and tensile measurements. Results obtained with these solutions are compared to those obtained in our Laboratory by using our own cleaning route. Moreover, XPS analyses are performed on small specimens that have been submitted to the same cleaning treatments in order to better understand the mechanical results of our specimens. (authors)

Hot spots and dark current in advanced plasma wakefield accelerators

Directory of Open Access Journals (Sweden)

G. G. Manahan

2016-01-01

Full Text Available Dark current can spoil witness bunch beam quality and acceleration efficiency in particle beam-driven plasma wakefield accelerators. In advanced schemes, hot spots generated by the drive beam or the wakefield can release electrons from higher ionization threshold levels in the plasma media. These electrons may be trapped inside the plasma wake and will then accumulate dark current, which is generally detrimental for a clear and unspoiled plasma acceleration process. Strategies for generating clean and robust, dark current free plasma wake cavities are devised and analyzed, and crucial aspects for experimental realization of such optimized scenarios are discussed.

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.

Application of plasma technology for the modification of polymer and textile materials

Directory of Open Access Journals (Sweden)

Radetić Maja M.

2004-01-01

Full Text Available Plasma treatment is based on the physico-chemical changes of the material surface and as an ecologically and economically acceptable process it can be an attractive alternative to conventional modifications. The possibilities of plasma technology application to the modification of polymer and textile materials are discussed. Different specific properties of the material can be achieved by plasma cleaning, etching, functionalization or polymerization. The final effects are strongly influenced by the treatment parameters (treatment time, pressure, power, gas flow, the applied gas and nature of the material. The plasma treatment of polymers is predominantly focused on cleaning and activation of the surfaces to increase adhesion, binding, wettability, dye ability and printability. Current studies deal more with plasma polymerization where an ultra thin film of plasma polymer is deposited on the material surface and, depending on the applied monomer, different specific properties can be obtained (i.e. chemical and thermal resistance, abrasion resistance, antireflexion, water repellence, etc.. Plasma application to textiles is mostly oriented toward wool and synthetic fibres, though some studies also consider cotton, hemp, flax and silk. The main goal of plasma treatment is to impart a more hydrophilic fibre surface and accordingly increase wettability, dye ability, printability and particularly, shrink resistance in the case of wool. Recent studies have favored technical textiles, where plasma polymerization can offer a wide range of opportunities.

The study of discharge cleaning in the JFT-2 tokamak with surface observation by AES

International Nuclear Information System (INIS)

Gomay, Yoshio; Tazima, Teruhiko; Fujisawa, Noboru; Suzuki, Norio; Konoshima, Shigeru

1976-07-01

Noticeable correlations were observed between the changes of discharge characteristics, wall conditions and typical mass peaks with discharge cleaning in the JFT-2 tokamak. Atomic composition of the vacuum wall surface observed by AES becomes constant with continuing discharge cleaning in the level except hydrogen and helium: 30-50% C, 20-30% Mo, 15-30% stainless steel elements and 10-15% O. The stable reproducible plasma with Z sub(eff)=4.5 was obtained in this wall condition. The limiter and vacuum wall materials (Mo and 304 stainless steel, respectively), carbon and oxygen were observed depositing on the wall in the thickness of about 300 A at the minimum inner radius of the vacuum chamber and 40 A nearly at the maximum after 2900 cleaning pulses. The mechanism determining the wall condition is also discussed. (auth.)

Improving the work function of the niobium surface of SRF cavities by plasma processing

International Nuclear Information System (INIS)

Tyagi, P.V.; Doleans, M.; Hannah, B.; Afanador, R.; McMahan, C.; Stewart, S.; Mammosser, J.; Howell, M.; Saunders, J.; Degraff, B.; Kim, S.-H.

2016-01-01

Highlights: • An in situ plasma processing for SNS SRF cavities has been developed to remove hydrocarbons from cavity surface. • Reactive oxygen plasma is very effective to remove hydrocarbons from niobium top surface. • Reactive oxygen plasma processing increases the work function of niobium surface in the range of 0.5–1.0 eV. • It was observed that hydrocarbons can migrate at plasma cleaned top surface from near surface regions when waiting in vacuum at room temperature. • Multiple cycles of plasma processing with waiting periods in between was found beneficial to mitigate such hydrocarbons migration at plasma cleaned surface. - Abstract: An in situ plasma processing technique using chemically reactive oxygen plasma to remove hydrocarbons from superconducting radio frequency cavity surfaces at room temperature has been developed at the spallation neutron source, at Oak Ridge National Laboratory. To understand better the interaction between the plasma and niobium surface, surface studies on small samples were performed. In this article, we report the results from those surface studies. The results show that plasma processing removes hydrocarbons from top surface and improves the surface work function by 0.5–1.0 eV. Improving the work function of RF surface of cavities can help to improve their operational performance.

Long-wavelength germanium photodetectors by ion implantation

International Nuclear Information System (INIS)

Wu, I.C.; Beeman, J.W.; Luke, P.N.; Hansen, W.L.; Haller, E.E.

1990-11-01

Extrinsic far-infrared photoconductivity in thin high-purity germanium wafers implanted with multiple-energy boron ions has been investigated. Initial results from Fourier transform spectrometer(FTS) measurements have demonstrated that photodetectors fabricated from this material have an extended long-wavelength threshold near 192μm. Due to the high-purity substrate, the ability to block the hopping conduction in the implanted IR-active layer yields dark currents of less than 100 electrons/sec at temperatures below 1.3 K under an operating bias of up to 70 mV. Optimum peak responsivity and noise equivalent power (NEP) for these sensitive detectors are 0.9 A/W and 5 x 10 -16 W/Hz 1/2 at 99 μm, respectively. The dependence of the performance of devices on the residual donor concentration in the implanted layer will be discussed. 12 refs., 4 figs

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

Gamma ray polarimetry using a position sensitive germanium detector

CERN Document Server

Kroeger, R A; Kurfess, J D; Phlips, B F

1999-01-01

Imaging gamma-ray detectors make sensitive polarimeters in the Compton energy regime by measuring the scatter direction of gamma rays. The principle is to capitalize on the angular dependence of the Compton scattering cross section to polarized gamma rays and measure the distribution of scatter directions within the detector. This technique is effective in a double-sided germanium detector between roughly 50 keV and 1 MeV. This paper reviews device characteristics important to the optimization of a Compton polarimeter, and summarizes measurements we have made using a device with a 5x5 cm active area, 1 cm thickness, and strip-electrodes on a 2 mm pitch.

Multiple pulse traveling wave excitation of neon-like germanium

International Nuclear Information System (INIS)

Moreno, J. C.; Nilsen, J.; Silva, L. B. da

1995-01-01

Traveling wave excitation has been shown to significantly increase the output intensity of the neon-like germanium x-ray laser. The driving laser pulse consisted of three 100 ps Gaussian laser pulses separated by 400 ps. Traveling wave excitation was employed by tilting the wave front of the driving laser by 45 degrees to match the propagation speed of the x-ray laser photons along the length of the target. We show results of experiments with the traveling wave, with no traveling wave, and against the traveling wave and comparisons to a numerical model. Gain was inferred from line intensity measurements at two lengths

Charge collection performance of a segmented planar high-purity germanium detector

Energy Technology Data Exchange (ETDEWEB)

Cooper, R.J. [Department of Physics, The University of Liverpool, Oliver Lodge Laboratory, Liverpool Merseyside L69 7ZE (United Kingdom)], E-mail: R.Cooper@liverpool.ac.uk; Boston, A.J.; Boston, H.C.; Cresswell, J.R.; Grint, A.N.; Harkness, L.J.; Nolan, P.J.; Oxley, D.C.; Scraggs, D.P. [Department of Physics, The University of Liverpool, Oliver Lodge Laboratory, Liverpool Merseyside L69 7ZE (United Kingdom); Lazarus, I.; Simpson, J. [STFC Daresbury Laboratory, Warrington, Cheshire WA4 4AD (United Kingdom); Dobson, J. [Rosemere Cancer Centre, Royal Preston Hospital, Preston PR2 9HT (United Kingdom)

2008-10-01

High-precision scans of a segmented planar high-purity germanium (HPGe) detector have been performed with a range of finely collimated gamma ray beams allowing the response as a function of gamma ray interaction position to be quantified. This has allowed the development of parametric pulse shape analysis (PSA) techniques and algorithms for the correction of imperfections in performance. In this paper we report on the performance of this detector, designed for use in a positron emission tomography (PET) development system.

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.

Study of the creep of germanium bi-crystals by X ray topography and electronic microscopy

International Nuclear Information System (INIS)

Gay, Marie-Odile

1981-01-01

This research thesis addresses the study of the microscopic as well as macroscopic aspect of the role of grain boundary during deformation, by studying the creep of Germanium bi-crystals. The objective was to observe interactions of network dislocations with the boundary as well as the evolution of dislocations in each grain. During the first stages of deformation, samples have been examined by X ray topography, a technique which suits well the observation of low deformed samples, provided their initial dislocation density is very low. At higher deformation, more conventional techniques of observation of sliding systems and electronic microscopy have been used. After some general recalls, the definition of twin boundaries and of their structure in terms of dislocation, a look at germanium deformation, and an overview of works performed on bi-crystals deformation, the author presents the experimental methods and apparatuses. He reports and discusses the obtained results at the beginning of deformation as well as during next phases

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

Development of the plasma operational regime in the large helical device by the various wall conditioning methods

International Nuclear Information System (INIS)

Nishimura, K.; Ashikawa, N.; Masuzaki, S.; Miyazawa, J.; Sagara, A.; Goto, M.; Peterson, B.J.; Komori, A.; Noda, N.; Ida, K.; Kaneko, O.; Kawahata, K.; Kobuchi, T.; Kubo, S.; Morita, S.; Osakabe, M.; Sakakibara, S.; Sakamoto, R.; Sato, K.; Shimozuma, T.; Takeiri, Y.; Tanaka, K.; Motojima, O.

2005-01-01

Experiments in the large helical device have been developing since the first discharge in 1998. Baking at 95 deg C, electron cyclotron resonance discharge cleaning, glow discharge cleaning, titanium gettering and boronization were attempted for wall conditioning. Using these conditioning techniques, the partial pressures of the oxidized gases, such as H 2 O, CO and CO 2 , were reduced gradually and the plasma operational regime enlarged. The glow discharge cleaning with the various working gases, such as hydrogen, helium, neon and argon, was effective in increasing the plasma purity. By this method, we obtained a central ion temperature of 10 keV. Boronization, which was started from FY2001, was also effective in reducing the radiation losses from impurities and in enlarging the density operational regime. We obtained a plasma stored energy of 1.31 MJ and an electron density of 2.4 x 10 20 m -3

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.

Cleaning of spent solvent and method of processing cleaning liquid waste

International Nuclear Information System (INIS)

Ozawa, Masaki; Kawada, Tomio; Tamura, Nobuhiko.

1993-01-01

Spent solvents discharged from a solvent extracting step mainly comprise n-dodecane and TBP and contain nuclear fission products and solvent degradation products. The spent solvents are cleaned by using a sodium chloride free detergent comprising hydrazine oxalate and hydrazine carbonate in a solvent cleaning device. Nitric acid is added to the cleaning liquid wastes containing spent detergents extracted from the solvent cleaning device, to control an acid concentration. The detergent liquid wastes of controlled acid concentration are sent to an electrolysis oxidation bath as electrolytes and electrochemically decomposed in carbonic acid gas, nitrogen gas and hydrogen gas. The decomposed gases are processed as off gases. The decomposed liquid wastes are processed as a waste nitric acid solution. This can provide more effective cleaning. In addition, the spent detergent can be easily decomposed in a room temperature region. Accordingly, the amount of wastes can be decreased. (I.N.)

Molybdenum blue reaction and determination of phosphorus in waters containing arsenic, silicon, and germanium

Science.gov (United States)

Levine, H.; Rowe, J.J.; Grimaldi, F.S.

1955-01-01

Microgram amounts of phosphate are usually determined by the molybdenum blue reaction, but this reaction is not specific for phosphorus. The research established the range of conditions under which phosphate, arsenate, silicate, and germanate give the molybdenum blue reaction for differentiating these elements, and developed a method for the determination of phosphate in waters containing up to 10 p.p.m. of the oxides of germanium, arsenic(V), and silicon. With stannous chloride or 1-amino-2-naphthol-4-sulfonic acid as the reducing agent no conditions were found for distinguishing silicate from germanate and phosphate from arsenate. In the recommended procedure the phosphate is concentrated by coprecipitation on aluminum hydroxide, and coprecipitated arsenic, germanium, and silicon are volatilized by a mixture of hydrofluoric, hydrochloric, and hydrobromic acids prior to the determination of phosphate. The authors are able to report that the total phosphorus content of several samples of sea water from the Gulf of Mexico ranged from 0.018 to 0.059 mg. of phosphorus pentoxide per liter of water.

Is dry cleaning all wet?

International Nuclear Information System (INIS)

Ryan, M.

1993-01-01

Chemical solvents from dry cleaning, particularly perchloroethylene (perc), have contributed to groundwater contamination, significant levels of air pollution in and around cleaners, and chemical accumulation in food. Questions are being raised about the process of cleaning clothes with chemical, and other less toxic cleaning methods are being explored. The EPA has focused attention on the 50 year old Friedburg method of cleaning, Ecoclean, which uses no dangerous chemicals and achieves comparable results. Unfortunately, the cleaning industry is resistant to change, so cutting back on amount of clothes that need dry cleaning and making sure labels aren't exaggerating when they say dry clean only, is frequently the only consumer option now

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

Millimeter-Wave Receiver Concepts for 77 GHz Automotive Radar in Silicon-Germanium Technology

CERN Document Server

Kissinger, Dietmar

2012-01-01

The book presents the analysis and design of integrated automotive radar receivers in Silicon-Germanium technology, for use in complex multi-channel radar transceiver front-ends in the 77GHz frequency band. The main emphasis of the work is the realization of high-linearity and low-power modular receiver channels as well as the investigation of millimeter-wave integrated test concepts for the receiver front-end.

WINDOW-CLEANING

CERN Multimedia

Environmental Section / ST-TFM

2001-01-01

The two-month window-cleaning session on the Meyrin, Prévessin and LEP sites will soon begin. The cleaning contractors will work from Monday to Saturday, every week from 4.00 a.m. to 8.00 p.m. The work will be organised so as to disturb users as little as possible. In any event, a work notice will be left in each office 24 hours beforehand. To prevent any damage to documents or items which could occur despite the precautions taken, please clear completely the window-sills and the area immediately around them. If, however, for valid reasons, the work cannot be done on the scheduled day, please inform the Environmental Section by telephoning: 73753 / 74233 / 72242 If you are going to be absent during this two-month period, we should be grateful if you would clear the above mentioned areas before your departure. REMINDER To allow more thorough cleaning of the entrance doors to buildings and also facilitate the weekly work of the cleaning contractors, we ask you to make use of the notice boards at the...

Plasma Surface Interactions Common to Advanced Fusion Wall Materials and EUV Lithography - Lithium and Tin

Science.gov (United States)

Ruzic, D. N.; Alman, D. A.; Jurczyk, B. E.; Stubbers, R.; Coventry, M. D.; Neumann, M. J.; Olczak, W.; Qiu, H.

2004-09-01

Advanced plasma facing components (PFCs) are needed to protect walls in future high power fusion devices. In the semiconductor industry, extreme ultraviolet (EUV) sources are needed for next generation lithography. Lithium and tin are candidate materials in both areas, with liquid Li and Sn plasma material interactions being critical. The Plasma Material Interaction Group at the University of Illinois is leveraging liquid metal experimental and computational facilities to benefit both fields. The Ion surface InterAction eXperiment (IIAX) has measured liquid Li and Sn sputtering, showing an enhancement in erosion with temperature for light ion bombardment. Surface Cleaning of Optics by Plasma Exposure (SCOPE) measures erosion and damage of EUV mirror samples, and tests cleaning recipes with a helicon plasma. The Flowing LIquid surface Retention Experiment (FLIRE) measures the He and H retention in flowing liquid metals, with retention coefficients varying between 0.001 at 500 eV to 0.01 at 4000 eV.

Novel modulator topology for corona plasma generation

NARCIS (Netherlands)

Ariaans, T.H.P.; Pemen, A.J.M.; Winands, G.J.J.; Liu, Z.; Heesch, van E.J.M.

2009-01-01

Gas cleaning using plasma technology is slowly introduced into industry nowadays. Several challenges still have to be overcome: increasing the scale, safety, life time and reducing costs. In 2006 we demonstrated a 20 kW nanosecond pulsed corona system. The electrical efficiency was > 90%. O-radical

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.

Influence of Chemical Precleaning on the Plasma Treatment Efficiency of Aluminum by RF Plasma Pencil

International Nuclear Information System (INIS)

Prysiazhnyi, Vadym; Slavicek, Pavel; Klima, Milos; Mikmekova, Eliska

2016-01-01

This paper is aimed to show the influence of initial chemical pretreatment prior to subsequent plasma activation of aluminum surfaces. The results of our study showed that the state of the topmost surface layer (i.e. the surface morphology and chemical groups) of plasma modified aluminum significantly depends on the chemical precleaning. Commonly used chemicals (isopropanol, trichlorethane, solution of NaOH in deionized water) were used as precleaning agents. The plasma treatments were done using a radio frequency driven atmospheric pressure plasma pencil developed at Masaryk University, which operates in Ar, Ar/O 2 gas mixtures. The effectiveness of the plasma treatment was estimated by the wettability measurements, showing high wettability improvement already after 0.3 s treatment. The effects of surface cleaning (hydrocarbon removal), surface oxidation and activation (generation of OH groups) were estimated using infrared spectroscopy. The changes in the surface morphology were measured using scanning electron microscopy. Optical emission spectroscopy measurements in the near-to-surface region with temperature calculations showed that plasma itself depends on the sample precleaning procedure. (paper)

Influence of Chemical Precleaning on the Plasma Treatment Efficiency of Aluminum by RF Plasma Pencil

Science.gov (United States)

Vadym, Prysiazhnyi; Pavel, Slavicek; Eliska, Mikmekova; Milos, Klima

2016-04-01

This paper is aimed to show the influence of initial chemical pretreatment prior to subsequent plasma activation of aluminum surfaces. The results of our study showed that the state of the topmost surface layer (i.e. the surface morphology and chemical groups) of plasma modified aluminum significantly depends on the chemical precleaning. Commonly used chemicals (isopropanol, trichlorethane, solution of NaOH in deionized water) were used as precleaning agents. The plasma treatments were done using a radio frequency driven atmospheric pressure plasma pencil developed at Masaryk University, which operates in Ar, Ar/O2 gas mixtures. The effectiveness of the plasma treatment was estimated by the wettability measurements, showing high wettability improvement already after 0.3 s treatment. The effects of surface cleaning (hydrocarbon removal), surface oxidation and activation (generation of OH groups) were estimated using infrared spectroscopy. The changes in the surface morphology were measured using scanning electron microscopy. Optical emission spectroscopy measurements in the near-to-surface region with temperature calculations showed that plasma itself depends on the sample precleaning procedure.

Beyond the intelligent-shell concept. The clean-mode-control for tearing perturbations

International Nuclear Information System (INIS)

Zanca, Paolo

2010-01-01

The Intelligent Shell scheme, where a grid of active coils counteracts in a feedback scheme the measurements provided by an identical grid of sensors, has shown some limitations in the control of the dynamo tearing modes in RFX-mod. The origin of the problem is the aliasing on the measurements coming from the high periodicity sideband harmonics produced by the discrete nature of the active coils. A more efficient feedback on tearing modes is obtained by removing the sidebands from the measurements, thereby counteracting the true tearing Fourier modes. In this scheme, named Clean-Mode-Control, the sidebands are computed in real time from the coils currents using the cylindrical geometry approximation. The Clean-Mode-Control significantly alleviates the wall-locking of tearing modes in RFX-mod, giving the possibility of operating at a plasma current (1.5 MA) never reached before in a RFP machine. These features are well explained by a MHD model describing the tearing mode dynamic under the viscous torque due to the fluid motion and the electromagnetic torques produced by the feedback, the conductive structures surrounding the plasma and the non-linear interaction between the different modes. Here some new results obtained with this model are discussed. In particular we will show that the edge radial field control improves by reducing the ratio between the delay introduced by the digital acquisition of the measurements and the time constant of the shell that contains the plasma. In this formulation the active coils are assumed to be located outside the shell. (author)

Point defect engineering strategies to retard phosphorous diffusion in germanium

KAUST Repository

Tahini, H. A.; Chroneos, Alexander I.; Grimes, Robin W.; Schwingenschlö gl, Udo; Bracht, Hartmut A.

2013-01-01

The diffusion of phosphorous in germanium is very fast, requiring point defect engineering strategies to retard it in support of technological application. Density functional theory corroborated with hybrid density functional calculations are used to investigate the influence of the isovalent codopants tin and hafnium in the migration of phosphorous via the vacancy-mediated diffusion process. The migration energy barriers for phosphorous are increased significantly in the presence of oversized isovalent codopants. Therefore, it is proposed that tin and in particular hafnium codoping are efficient point defect engineering strategies to retard phosphorous migration. © the Owner Societies 2013.

Dark Matter Search with sub-keV Germanium Detectors at the China Jinping Underground Laboratory

International Nuclear Information System (INIS)

Yue Qian; Wong, Henry T

2012-01-01

Germanium detectors with sub-keV sensitivities open a window to search for low-mass WIMP dark matter. The CDEX-TEXONO Collaboration is conducting the first research program at the new China Jinping Underground Laboratory with this approach. The status and plans of the laboratory and the experiment are discussed.

Automated cleaning of electronic components

International Nuclear Information System (INIS)

Drotning, W.; Meirans, L.; Wapman, W.; Hwang, Y.; Koenig, L.; Petterson, B.

1994-01-01

Environmental and operator safety concerns are leading to the elimination of trichloroethylene and chlorofluorocarbon solvents in cleaning processes that remove rosin flux, organic and inorganic contamination, and particulates from electronic components. Present processes depend heavily on these solvents for manual spray cleaning of small components and subassemblies. Use of alternative solvent systems can lead to longer processing times and reduced quality. Automated spray cleaning can improve the quality of the cleaning process, thus enabling the productive use of environmentally conscious materials, while minimizing personnel exposure to hazardous materials. We describe the development of a prototype robotic system for cleaning electronic components in a spray cleaning workcell. An important feature of the prototype system is the capability to generate the robot paths and motions automatically from the CAD models of the part to be cleaned, and to embed cleaning process knowledge into the automatically programmed operations

Program LEP to addition of gamma spectra from germanium detectors; Programa LEPS para suma de espectros gammas de detectores de germanio

Energy Technology Data Exchange (ETDEWEB)

Romero, L

1986-07-01

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.

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

Environment pollution control and cleaning processes by means of plasma techniques

International Nuclear Information System (INIS)

Amoru, Dzh.; Morvan, D.; Kavadias, S.

2005-01-01

The European Community introduces the strict standards for air and water pollution and for waste treatment. To meet the mentioned standards one proposes to make use of laser spectroscopy with time resolution and with induced breakdown enabling to perform the prompt analysis without sampling with high sensitivity for all elements of the periodic system. In case of plasma treatment of fly ashes and of polluted soils the mass spectrometry base or the optical emission spectrometry base check of volatile organic compounds takes a few seconds. The paper also describes plasma neutralization of organic volatile compounds in air flow following the DBD-procedure to neutralize of or to trap molecules of polycyclic aromatic hydrocarbons [ru

Plasma impurity-control studies in CTX

International Nuclear Information System (INIS)

Barnes, C.W.; Henins, I.; Hoida, H.W.; Jarboe, T.R.; Linford, R.K.; Marshall, J.; Sherwood, A.R.; Tuszewski, M.

1981-01-01

In the past, magnetized coaxial gun generated Compact Toroids (CTs) have exhibited magnetic field and density lifetimes of about 250 to 350 μs and electron temperatures of about 10 eV. In recent experiments, after hydrogen discharge cleaning the gun and flux conserver surfaces, the lifetimes have been extended to 550 μs. This improvement in lifetime, together with spectroscopic and bolometric measurements, are consistent with the interpretation that the CT plasma losses are impurity dominated and that discharge cleaning is reducing the impurities. Details of these measurements are described as well as successful experiments which led to a more open flux conserver

Plasma impurity-control studies in CTX

Energy Technology Data Exchange (ETDEWEB)

Barnes, C.W.; Henins, I.; Hoida, H.W.; Jarboe, T.R.; Linford, R.K.; Marshall, J.; Sherwood, A.R.; Tuszewski, M.

1981-01-01

In the past, magnetized coaxial gun generated Compact Toroids (CTs) have exhibited magnetic field and density lifetimes of about 250 to 350 ..mu..s and electron temperatures of about 10 eV. In recent experiments, after hydrogen discharge cleaning the gun and flux conserver surfaces, the lifetimes have been extended to 550 ..mu..s. This improvement in lifetime, together with spectroscopic and bolometric measurements, are consistent with the interpretation that the CT plasma losses are impurity dominated and that discharge cleaning is reducing the impurities. Details of these measurements are described as well as successful experiments which led to a more open flux conserver.

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.

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

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)

Cold plasmas

International Nuclear Information System (INIS)

Franz, G.

1990-01-01

This textbook discusses the following topics: Phenomenological description of a direct current glow discharge; the plasma (temperature distribution and measurement, potential variation, electron energy distribution function, charge neutralization, wall potentials, plasma oscillations); Production of charge carriers (ions, electrons, ionization in the cathode zone, negative glowing zone, Faraday dark space, positive column, anode zone, hollow cathode discharges); RF-discharges (charge carrier production, RF-Shields, scattering mechanisms); Sputtering (ion-surface interaction, kinetics, sputtering yield and energy distribution, systems and conditions, film formation and stresses, contamination, bias techniques, multicomponent film deposition, cohesion, magnetrons, triode systems, plasma enhanced chemical vapor deposition); Dry etching (sputter etching, reactive etching, topography, process control, quantitative investigations); Etching mechanisms (etching of Si and SiO 2 with CF 4 , of III/V-compound-semiconductors, combination of isotrope and anisotrope etching methods, surface cleaning); ion beam systems (applications, etching); Dyclotron-resonance-systems (electron cyclotron resonance systems, whistler-sources and 'resonant inductive plasma etching'); Appendix (electron energy distribution functions, Bohm's transition zone, plasma oscillations, scattering cross sections and mean free path, metastable states, Child-Langmuir-Schottky equation, loss mechanisms, charge carrier distribution in the positive column, breakdown at high frequencies, motion in a magnetic field, skin depth of an electric field for a HF-discharge, whistler waves, dispersion relations for plane wave propagation). (orig.) With 138 figs

X-ray spectroscopy of warm and hot electron components in the CAPRICE source plasma at EIS testbench at GSI

Energy Technology Data Exchange (ETDEWEB)

Mascali, D., E-mail: davidmascali@lns.infn.it; Celona, L.; Castro, G.; Torrisi, G.; Neri, L.; Gammino, S.; Ciavola, G. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, – Via S. Sofia 62, 95123 Catania (Italy); Maimone, F.; Maeder, J.; Tinschert, K.; Spaedtke, K. P.; Rossbach, J.; Lang, R. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstrasse 1, 64291 Darmstadt (Germany); Romano, F. P. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, – Via S. Sofia 62, 95123 Catania (Italy); IBAM, CNR, Via Biblioteca 4, 95124 Catania (Italy); Musumarra, A.; Altana, C.; Caliri, C. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, – Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, via S. Sofia 64, 95123 Catania (Italy)

2014-02-15

An experimental campaign aiming to detect X radiation emitted by the plasma of the CAPRICE source – operating at GSI, Darmstadt – has been carried out. Two different detectors (a SDD – Silicon Drift Detector and a HpGe – hyper-pure Germanium detector) have been used to characterize the warm (2–30 keV) and hot (30–500 keV) electrons in the plasma, collecting the emission intensity and the energy spectra for different pumping wave frequencies and then correlating them with the CSD of the extracted beam measured by means of a bending magnet. A plasma emissivity model has been used to extract the plasma density along the cone of sight of the SDD and HpGe detectors, which have been placed beyond specific collimators developed on purpose. Results show that the tuning of the pumping frequency considerably modifies the plasma density especially in the warm electron population domain, which is the component responsible for ionization processes: a strong variation of the plasma density near axis region has been detected. Potential correlations with the charge state distribution in the plasma are explored.

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.