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Sample records for p-type semiconducting behavior

  1. Semiconducting p-type MgNiO:Li epitaxial films fabricated by cosputtering method

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Yong Hun; Chun, Sung Hyun; Cho, Hyung Koun [School of Advanced Materials Science and Engineering, Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon, Gyeonggi-do 440-746 (Korea, Republic of)

    2013-07-15

    Li-doped ternary Mg{sub x}Ni{sub 1-x}O thin films were deposited on (0001) Al{sub 2}O{sub 3} substrates by a radio frequency (RF) magnetron cosputtering method with MgO and NiO:Li targets. The Mg mole fraction and Li content were relatively controlled by changing RF power for the MgO target over a range of 0-300 W, while the NiO:Li target was kept at 150 W. As a result, all films were epitaxially grown on (0001) Al{sub 2}O{sub 3} substrates with the relationship of [110]{sub NiO}||[1110]{sub Al2O3}, [112]{sub NiO}||[2110]{sub Al2O3} (in-plane), and [111]{sub NiO}||[0001]{sub Al2O3} (out-of-plane), and showed p-type semiconducting properties. Furthermore, from x-ray diffraction patterns, the authors found that MgO was effectively mixed with NiO:Li without structural deformation due to low lattice mismatch (0.8%) between NiO and MgO. However, the excess Li contents degraded the crystallinity of the MgNiO films. The band-gap of films was continuously shifted from 3.66 eV (339 nm) to 4.15 eV (299 nm) by the RF power of the MgO target. A visible transmittance of more than 80% was exhibited at RF powers higher than 200 W. Ultimately, the electrical resistivity of p-type MgNiO films was improved from 7.5 to 673.5 {Omega}cm, indicating that the Li-doped MgNiO films are good candidates for transparent p-type semiconductors.

  2. p-Type semiconducting nickel oxide as an efficiency-enhancing anodal interfacial layer in bulk heterojunction solar cells

    Science.gov (United States)

    Irwin, Michael D; Buchholz, Donald B; Marks, Tobin J; Chang, Robert P. H.

    2014-11-25

    The present invention, in one aspect, relates to a solar cell. In one embodiment, the solar cell includes an anode, a p-type semiconductor layer formed on the anode, and an active organic layer formed on the p-type semiconductor layer, where the active organic layer has an electron-donating organic material and an electron-accepting organic material.

  3. Enhanced H2S Sensing Performance of a p-type Semiconducting PdO-NiO Nanoscale Heteromixture

    Science.gov (United States)

    Balamurugan, C.; Jeong, Y. J.; Lee, D. W.

    2017-10-01

    Semiconducting nanocrystalline nickel oxide (NiO) and PdO-doped NiO heteromixture (2, 5 and 10 wt%) have been synthesized via a metal-citrate complex method. The obtained materials were further characterized using TG/DTA, FT-IR, UV-vis, XRD, XPS, BET/BJH, SEM and TEM analyses to determine their structural and morphological properties. The results indicated that the spherical, uniform PdO nanoparticles were densely deposited on the NiO surface mainly in diameters of 10-15 nm. Moreover, the existence of various defect states was also analyzed with the help of photoluminescence (PL) spectroscopy. The gas response characteristics of synthesized materials were evaluated in the presence and absence of toxic gases such as hydrogen sulfide (H2S), carbon monoxide (CO), liquid petroleum gas (LPG), and ethanol (C2H5OH). The experimental results revealed that the sensitivity and selectivity of the NiO-based sensor material are dependent on the weight% of PdO loading in the NiO nanopowder. Among the investigated compound, the 5 wt% PdO-doped NiO sensor material showed excellent sensitivity and selectivity to 100 ppm H2S with a fast response/recovery characteristics of 6 s and 10 s, respectively. Furthermore, the 5 wt% PdO-doped NiO based sensor showed a linear relationship between the different concentrations of H2S gas and a significantly higher response to H2S even at the low concentration of 20 ppm (43%) at 60 °C. The dominant H2S gas sensing mechanisms in the NiO and 5 wt% PdO-doped NiO nanomaterials are systematically discussed based on the obtained characterization results.

  4. The electrical, optical, structural and thermoelectrical characterization of n- and p-type cobalt-doped SnO 2 transparent semiconducting films prepared by spray pyrolysis technique

    Science.gov (United States)

    Bagheri-Mohagheghi, Mohammad-Mehdi; Shokooh-Saremi, Mehrdad

    2010-10-01

    The electrical, optical and structural properties of Cobalt (Co) doped SnO 2 transparent semiconducting thin films, deposited by the spray pyrolysis technique, have been studied. The SnO 2:Co films, with different Co-content, were deposited on glass substrates using an aqueous-ethanol solution consisting of tin and cobalt chlorides. X-ray diffraction studies showed that the SnO 2:Co films were polycrystalline only with tin oxide phases and preferential orientations along (1 1 0) and (2 1 1) planes and grain sizes in the range 19-82 nm. Optical transmittance spectra of the films showed high transparency ∼75-90% in the visible region, decreasing with increase in Co-doping. The optical absorption edge for undoped SnO 2 films was found to be 3.76 eV, while for higher Co-doped films shifted toward higher energies (shorter wavelengths) in the range 3.76-4.04 eV and then slowly decreased again to 4.03 eV. A change in sign of the Hall voltage and Seebeck coefficient was observed for a specific acceptor dopant level ∼11.4 at% in film and interpreted as a conversion from n-type to p-type conductivity. The thermoelectric electro-motive force (e.m.f.) of the films was measured in the temperature range 300-500 K and Seebeck coefficients were found in the range from -62 to +499 μVK -1 for various Co-doped SnO 2 films.

  5. The electrical, optical, structural and thermoelectrical characterization of n- and p-type cobalt-doped SnO2 transparent semiconducting films prepared by spray pyrolysis technique

    International Nuclear Information System (INIS)

    Bagheri-Mohagheghi, Mohammad-Mehdi; Shokooh-Saremi, Mehrdad

    2010-01-01

    The electrical, optical and structural properties of Cobalt (Co) doped SnO 2 transparent semiconducting thin films, deposited by the spray pyrolysis technique, have been studied. The SnO 2 :Co films, with different Co-content, were deposited on glass substrates using an aqueous-ethanol solution consisting of tin and cobalt chlorides. X-ray diffraction studies showed that the SnO 2 :Co films were polycrystalline only with tin oxide phases and preferential orientations along (1 1 0) and (2 1 1) planes and grain sizes in the range 19-82 nm. Optical transmittance spectra of the films showed high transparency ∼75-90% in the visible region, decreasing with increase in Co-doping. The optical absorption edge for undoped SnO 2 films was found to be 3.76 eV, while for higher Co-doped films shifted toward higher energies (shorter wavelengths) in the range 3.76-4.04 eV and then slowly decreased again to 4.03 eV. A change in sign of the Hall voltage and Seebeck coefficient was observed for a specific acceptor dopant level ∼11.4 at% in film and interpreted as a conversion from n-type to p-type conductivity. The thermoelectric electro-motive force (e.m.f.) of the films was measured in the temperature range 300-500 K and Seebeck coefficients were found in the range from -62 to +499 μVK -1 for various Co-doped SnO 2 films.

  6. Effect of p-type multi-walled carbon nanotubes for improving hydrogen storage behaviors

    International Nuclear Information System (INIS)

    Lee, Seul-Yi; Yop Rhee, Kyong; Nahm, Seung-Hoon; Park, Soo-Jin

    2014-01-01

    In this study, the hydrogen storage behaviors of p-type multi-walled carbon nanotubes (MWNTs) were investigated through the surface modification of MWNTs by immersing them in sulfuric acid (H 2 SO 4 ) and hydrogen peroxide (H 2 O 2 ) at various ratios. The presence of acceptor-functional groups on the p-type MWNT surfaces was confirmed by X-ray photoelectron spectroscopy. Measurement of the zeta-potential determined the surface charge transfer and dispersion of the p-type MWMTs, and the hydrogen storage capacity was evaluated at 77 K and 1 bar. From the results obtained, it was found that acceptor-functional groups were introduced onto the MWNT surfaces, and the dispersion of MWNTs could be improved depending on the acid-mixed treatment conditions. The hydrogen storage was increased by acid-mixed treatments of up to 0.36 wt% in the p-type MWNTs, compared with 0.18 wt% in the As-received MWNTs. Consequently, the hydrogen storage capacities were greatly influenced by the acceptor-functional groups of p-type MWNT surfaces, resulting in increased electron acceptor–donor interaction at the interfaces. - Graphical abstract: Hydrogen storage behaviors of the p-type MWNTs with the acid-mixed treatments are described. Display Omitted Display Omitted

  7. Ultraviolet light-absorbing and emitting diodes consisting of a p-type transparent-semiconducting NiO film deposited on an n-type GaN homoepitaxial layer

    Science.gov (United States)

    Nakai, Hiroshi; Sugiyama, Mutsumi; Chichibu, Shigefusa F.

    2017-05-01

    Gallium nitride (GaN) and related (Al,Ga,In)N alloys provide practical benefits in the production of light-emitting diodes (LEDs) and laser diodes operating in ultraviolet (UV) to green wavelength regions. However, obtaining low resistivity p-type AlN or AlGaN of large bandgap energies (Eg) is a critical issue in fabricating UV and deep UV-LEDs. NiO is a promising candidate for useful p-type transparent-semiconducting films because its Eg is 4.0 eV and it can be doped into p-type conductivity of sufficiently low resistivity. By using these technologies, heterogeneous junction diodes consisting of a p-type transparent-semiconducting polycrystalline NiO film on an n-type single crystalline GaN epilayer on a low threading-dislocation density, free-standing GaN substrate were fabricated. The NiO film was deposited by using the conventional RF-sputtering method, and the GaN homoepitaxial layer was grown by metalorganic vapor phase epitaxy. They exhibited a significant photovoltaic effect under UV light and also exhibited an electroluminescence peak at 3.26 eV under forward-biased conditions. From the conduction and valence band (EV) discontinuities, the NiO/GaN heterointerface is assigned to form a staggered-type (TYPE-II) band alignment with the EV of NiO higher by 2.0 eV than that of GaN. A rectifying property that is consistent with the proposed band diagram was observed in the current-voltage characteristics. These results indicate that polycrystalline NiO functions as a hole-extracting and injecting layer of UV optoelectronic devices.

  8. p-Type semiconducting nickel oxide as an efficiency-enhancing anode interfacial layer in polymer bulk-heterojunction solar cells

    Science.gov (United States)

    Irwin, Michael D.; Buchholz, D. Bruce; Hains, Alexander W.; Chang, Robert P. H.; Marks, Tobin J.

    2008-01-01

    To minimize interfacial power losses, thin (5–80 nm) layers of NiO, a p-type oxide semiconductor, are inserted between the active organic layer, poly(3-hexylthiophene) (P3HT) + [6,6]-phenyl-C61 butyric acid methyl ester (PCBM), and the ITO (tin-doped indium oxide) anode of bulk-heterojunction ITO/P3HT:PCBM/LiF/Al solar cells. The interfacial NiO layer is deposited by pulsed laser deposition directly onto cleaned ITO, and the active layer is subsequently deposited by spin-coating. Insertion of the NiO layer affords cell power conversion efficiencies as high as 5.2% and enhances the fill factor to 69% and the open-circuit voltage (Voc) to 638 mV versus an ITO/P3HT:PCBM/LiF/Al control device. The value of such hole-transporting/electron-blocking interfacial layers is clearly demonstrated and should be applicable to other organic photovoltaics.

  9. Carrier removal and defect behavior in p-type InP

    Science.gov (United States)

    Weinberg, I.; Swartz, C. K.; Drevinsky, P. J.

    1992-01-01

    A simple expression, obtained from the rate equation for defect production, was used to relate carrier removal to defect production and hole trapping rates in p-type InP after irradiation by 1-MeV electrons. Specific contributions to carrier removal from defect levels H3, H4, and H5 were determined from combined deep-level transient spectroscopy (DLTS) and measured carrier concentrations. An additional contribution was attributed to one or more defects not observed by the present DLTS measurements. The high trapping rate observed for H5 suggests that this defect, if present in relatively high concentration, could be dominant in p-type InP.

  10. Semiconducting behavior of the anodically passive films formed on AZ31B alloy

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    A. Fattah-alhosseini

    2014-12-01

    Full Text Available This work includes determination of the semiconductor character and estimation of the dopant levels in the passive film formed on AZ31B alloy in 0.01 M NaOH, as well as the estimation of the passive film thickness as a function of the film formation potential. Mott–Schottky analysis revealed that the passive films displayed n-type semiconductive characteristics, where the oxygen vacancies and interstitials preponderated. Based on the Mott–Schottky analysis, it was shown that the calculated donor density increases linearly with increasing the formation potential. Also, the electrochemical impedance spectroscopy (EIS results indicated that the thickness of the passive film was decreased linearly with increasing the formation potential. The results showed that decreasing the formation potential offer better conditions for forming the passive films with higher protection behavior, due to the growth of a much thicker and less defective films.

  11. N-Type Semiconducting Behavior of Copper Octafluorophthalocyanine in an Organic Field-Effect Transistor

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    Akane Matumoto

    2017-10-01

    Full Text Available Based on the crystal structure analysis, the overlap integral between the frontier molecular orbitals of adjacent F8CuPcs in the one-dimensional chain is estimated: the overlap integral between the lowest unoccupied molecular orbitals is 5.4 × 10−3, which is larger than that in a typical n-type semiconducing material F16CuPc (2.1 × 10−3, whereas that between the highest occupied molecular orbitals is 2.9 × 10−4. Contrary to previous studies in air, we found that an organic field-effect transistor (OFET composed of F8CuPc essentially shows clear n-type semiconducting behavior in vacuum.

  12. Photo-response behavior of organic transistors based on thermally annealed semiconducting diketopyrrolopyrrole core

    Science.gov (United States)

    Tarsoly, Gergely; Pyo, Seungmoon

    2018-06-01

    We report the opto-electrical response of organic field-effect transistors based on a thin-film of a semiconducting diketopyrrolopyrrole (DPP) core, a popular building block for molecular semiconductors, and a polymeric gate dielectric. The thin-film of the DPP core was thermally annealed at different temperatures under N2 atmosphere to investigate the relationship between the annealing temperature and the electrical properties of the device. The results showed that the annealing process induces morphological changes in the thin film, and properly controlling the thermal annealing conditions can enhance the device performance. In addition, we also investigated in detail the photo-response behaviors by analyzing the responsivity (R) of the device with the optimally annealed DPP-core thin film under two light illumination conditions by considering the irradiance absorbed by the thin film instead of the total irradiance of the light source. We found that the proposed model could lead to a light-source-independent description of the photo-response behavior of the device, and which can be used for other applications.

  13. Photoluminescence and semiconducting behavior of Fe, Co, Ni and Cu implanted in heavy metal oxide glasses

    Directory of Open Access Journals (Sweden)

    Mohamed A. Marzouk

    2016-07-01

    Full Text Available Transition metal ions (0.5 wt% of Fe2O3, CoO, NiO or CuO doped heavy metal oxide glasses having chemical composition of 60PbO·20Bi2O3·20 MxOy mol% (where MxOy = B2O3 or SiO2 or P2O5 were prepared by conventional melt annealing method. Combined optical and photoluminescence properties have been measured and employed to evaluate the prepared glassy samples. From the absorption edge data, the values of the optical band gap Eopt, Urbach energy (ΔE and refractive index were calculated to estimate semiconducting behavior. Photoluminescence and values of the optical energy gap were found to be dependent on the glass composition. The variations of the photoluminescence intensity, values of optical band gap, Urbach energy and refractive index gave an indication to use the prepared glasses for design of novel functional optical materials with higher optical performance.

  14. Improvement on p-type CVD diamond semiconducting properties by fabricating thin heavily-boron-doped multi-layer clusters isolated each other in unintentionally boron-doped diamond layer

    Science.gov (United States)

    Maida, Osamu; Tabuchi, Tomohiro; Ito, Toshimichi

    2017-12-01

    We have developed a new fabrication process to decrease the effective activation energy of B atoms doped in diamond without a significant decrease in the carrier mobility by fabricating heavily B-doped clusters with very low mobility which are embedded in lightly-B-doped diamond layers. The resistivities of the heavily B-doped and unintentionally B-doped diamond stacked layers had almost no temperature dependence, suggesting the presence of an impurity-band conduction in these diamond layers. On the other hand, the resistivities of the samples after the embedding growth process of the stacked layers that had been appropriately divided to innumerable small clusters by means of a suitable etching process increased with decreasing the temperature from 330 to 130 K. The effective activation energies and Hall mobilities at room temperature of both samples were estimated to be 0.21 eV, 106 cm2 V-1 s-1 for micron-sized clusters and 0.23 eV, 470 cm2 V-1 s-1 for nano-sized clusters, respectively, indicating that the diamond film structure fabricated in this work is effective for the improvement of the p-type performance for the B-doped CVD diamond.

  15. Development of N- and P- Types of Semiconducting Polymers

    Science.gov (United States)

    2015-03-05

    type, oligomeric donor monomers with fused thienobenzothiophene structures. These monomers are copolymerized with fluorinated thieno[3,4- b]thiophene...copolymerized with fluorinated thieno[3,4- b]thiophene ester to form a series of polymers which were investigated as donor materials in polymer/fullerene...effective but somewhat toxic drug, significantly lowered the dose of colistin required for killing bacteria and thus increased its safety. These

  16. PREFACE: Semiconducting oxides Semiconducting oxides

    Science.gov (United States)

    Catlow, Richard; Walsh, Aron

    2011-08-01

    Semiconducting oxides are amongst the most widely studied and topical materials in contemporary condensed matter science, with interest being driven both by the fundamental challenges posed by their electronic and magnetic structures and properties, and by the wide range of applications, including those in catalysis and electronic devices. This special section aims to highlight recent developments in the physics of these materials, and to show the link between developing fundamental understanding and key application areas of oxide semiconductors. Several aspects of the physics of this wide and expanding range of materials are explored in this special section. Transparent semiconducting oxides have a growing role in several technologies, but challenges remain in understanding their electronic structure and the physics of charge carriers. A related problem concerns the nature of redox processes and the reactions which interconvert defects and charge carriers—a key issue which may limit the extent to which doping strategies may be used to alter electronic properties. The magnetic structures of the materials pose several challenges, while surface structures and properties are vital in controlling catalytic properties, including photochemical processes. The field profits from and exploits a wide range of contemporary physical techniques—both experimental and theoretical. Indeed, the interplay between experiment and computation is a key aspect of contemporary work. A number of articles describe applications of computational methods whose use, especially in modelling properties of defects in these materials, has a long and successful history. Several papers in this special section relate to work presented at a symposium within the European Materials Research Society (EMRS) meeting held in Warsaw in September 2010, and we are grateful to the EMRS for supporting this symposium. We would also like to thank the editorial staff of Journal of Physics: Condensed Matter for

  17. Impact of semiconducting electrodes on the electroresistance of ferroelectric tunnel junctions

    Science.gov (United States)

    Asa, M.; Bertacco, R.

    2018-02-01

    Ferroelectric tunnel junctions are promising candidates for the realization of energy-efficient digital memories and analog memcomputing devices. In this work, we investigate the impact of a semiconducting layer in series to the junction on the sign of electroresistance. To this scope, we compare tunnel junctions fabricated out of Pt/BaTiO3/La1/3Sr2/3MnO3 (LSMO) and Pt/BaTiO3/Nb:SrTiO3 (Nb:STO) heterostructures, displaying an opposite sign of the electroresistance. By capacitance-voltage profiling, we observe a behavior typical of Metal-Oxide-Semiconductor tunnel devices in both cases but compatible with the opposite sign of charge carriers in the semiconducting layer. While Nb:STO displays the expected n-type semiconducting character, metallic LSMO develops an interfacial p-type semiconducting layer. The different types of carriers at the semiconducting interfaces and the modulation of the depleted region by the ferroelectric charge have a deep impact on electroresistance, possibly accounting for the different sign observed in the two systems.

  18. Comprehensive study of the electronic and optical behavior of highly degenerate p-type Mg-doped GaN and AlGaN

    Science.gov (United States)

    Gunning, Brendan P.; Fabien, Chloe A. M.; Merola, Joseph J.; Clinton, Evan A.; Doolittle, W. Alan; Wang, Shuo; Fischer, Alec M.; Ponce, Fernando A.

    2015-01-01

    The bulk and 2-dimensional (2D) electrical transport properties of heavily Mg-doped p-type GaN films grown on AlN buffer layers by Metal Modulated Epitaxy are explored. Distinctions are made between three primary p-type conduction mechanisms: traditional valence band conduction, impurity band conduction, and 2D conduction within a 2D hole gas at a hetero-interface. The bulk and 2D contributions to the overall carrier transport are identified and the relative contributions are found to vary strongly with growth conditions. Films grown with III/V ratio less than 1.5 exhibit high hole concentrations exceeding 2 × 1019 cm-3 with effective acceptor activation energies of 51 meV. Films with III/V ratios greater than 1.5 exhibit lower overall hole concentrations and significant contributions from 2D transport at the hetero-interface. Films grown with III/V ratio of 1.2 and Mg concentrations exceeding 2 × 1020 cm-3 show no detectable inversion domains or Mg precipitation. Highly Mg-doped p-GaN and p-AlGaN with Al fractions up to 27% similarly exhibit hole concentrations exceeding 2 × 1019 cm-3. The p-GaN and p-Al0.11Ga0.89N films show broad ultraviolet (UV) photoluminescence peaks, which intercept the valence band, supporting the presence of a Mg acceptor band. Finally, a multi-quantum-well light-emitting diode (LED) and p-i-n diode are grown, both of which demonstrate rectifying behavior with turn-on voltages of 3-3.5 V and series resistances of 6-10 Ω without the need for any post-metallization annealing. The LED exhibits violet-blue luminescence at 425 nm, while the p-i-n diode shows UV luminescence at 381 nm, and both devices still show substantial light emission even when submerged in liquid nitrogen at 77 K.

  19. Comprehensive study of the electronic and optical behavior of highly degenerate p-type Mg-doped GaN and AlGaN

    Energy Technology Data Exchange (ETDEWEB)

    Gunning, Brendan P.; Fabien, Chloe A. M.; Merola, Joseph J.; Clinton, Evan A.; Doolittle, W. Alan, E-mail: alan.doolittle@ece.gatech.edu [School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Wang, Shuo; Fischer, Alec M.; Ponce, Fernando A. [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States)

    2015-01-28

    The bulk and 2-dimensional (2D) electrical transport properties of heavily Mg-doped p-type GaN films grown on AlN buffer layers by Metal Modulated Epitaxy are explored. Distinctions are made between three primary p-type conduction mechanisms: traditional valence band conduction, impurity band conduction, and 2D conduction within a 2D hole gas at a hetero-interface. The bulk and 2D contributions to the overall carrier transport are identified and the relative contributions are found to vary strongly with growth conditions. Films grown with III/V ratio less than 1.5 exhibit high hole concentrations exceeding 2 × 10{sup 19} cm{sup −3} with effective acceptor activation energies of 51 meV. Films with III/V ratios greater than 1.5 exhibit lower overall hole concentrations and significant contributions from 2D transport at the hetero-interface. Films grown with III/V ratio of 1.2 and Mg concentrations exceeding 2 × 10{sup 20} cm{sup −3} show no detectable inversion domains or Mg precipitation. Highly Mg-doped p-GaN and p-AlGaN with Al fractions up to 27% similarly exhibit hole concentrations exceeding 2 × 10{sup 19} cm{sup −3}. The p-GaN and p-Al{sub 0.11}Ga{sub 0.89}N films show broad ultraviolet (UV) photoluminescence peaks, which intercept the valence band, supporting the presence of a Mg acceptor band. Finally, a multi-quantum-well light-emitting diode (LED) and p-i-n diode are grown, both of which demonstrate rectifying behavior with turn-on voltages of 3–3.5 V and series resistances of 6–10 Ω without the need for any post-metallization annealing. The LED exhibits violet-blue luminescence at 425 nm, while the p-i-n diode shows UV luminescence at 381 nm, and both devices still show substantial light emission even when submerged in liquid nitrogen at 77 K.

  20. Comprehensive study of the electronic and optical behavior of highly degenerate p-type Mg-doped GaN and AlGaN

    International Nuclear Information System (INIS)

    Gunning, Brendan P.; Fabien, Chloe A. M.; Merola, Joseph J.; Clinton, Evan A.; Doolittle, W. Alan; Wang, Shuo; Fischer, Alec M.; Ponce, Fernando A.

    2015-01-01

    The bulk and 2-dimensional (2D) electrical transport properties of heavily Mg-doped p-type GaN films grown on AlN buffer layers by Metal Modulated Epitaxy are explored. Distinctions are made between three primary p-type conduction mechanisms: traditional valence band conduction, impurity band conduction, and 2D conduction within a 2D hole gas at a hetero-interface. The bulk and 2D contributions to the overall carrier transport are identified and the relative contributions are found to vary strongly with growth conditions. Films grown with III/V ratio less than 1.5 exhibit high hole concentrations exceeding 2 × 10 19 cm −3 with effective acceptor activation energies of 51 meV. Films with III/V ratios greater than 1.5 exhibit lower overall hole concentrations and significant contributions from 2D transport at the hetero-interface. Films grown with III/V ratio of 1.2 and Mg concentrations exceeding 2 × 10 20 cm −3 show no detectable inversion domains or Mg precipitation. Highly Mg-doped p-GaN and p-AlGaN with Al fractions up to 27% similarly exhibit hole concentrations exceeding 2 × 10 19 cm −3 . The p-GaN and p-Al 0.11 Ga 0.89 N films show broad ultraviolet (UV) photoluminescence peaks, which intercept the valence band, supporting the presence of a Mg acceptor band. Finally, a multi-quantum-well light-emitting diode (LED) and p-i-n diode are grown, both of which demonstrate rectifying behavior with turn-on voltages of 3–3.5 V and series resistances of 6–10 Ω without the need for any post-metallization annealing. The LED exhibits violet-blue luminescence at 425 nm, while the p-i-n diode shows UV luminescence at 381 nm, and both devices still show substantial light emission even when submerged in liquid nitrogen at 77 K

  1. Multifunctional uranyl hybrid materials: structural diversities as a function of pH, luminescence with potential nitrobenzene sensing, and photoelectric behavior as p-type semiconductors.

    Science.gov (United States)

    Song, Jian; Gao, Xue; Wang, Zhi-Nan; Li, Cheng-Ren; Xu, Qi; Bai, Feng-Ying; Shi, Zhong-Feng; Xing, Yong-Heng

    2015-09-21

    A series of uranyl-organic frameworks (UOFs), {[(UO2)2(H2TTHA)(H2O)]·4,4'-bipy·2H2O}n (1), {[(UO2)3(TTHA)(H2O)3]}n (2), and {[(UO2)5(TTHA) (HTTHA)(H2O)3]·H3O}n (3), have been obtained by the hydrothermal reaction of uranyl acetate with a flexible hexapodal ligand (1,3,5-triazine-2,4,6-triamine hexaacetic acid, H6TTHA). These compounds exhibited three distinct 3D self-assembly architectures as a function of pH by single-crystal structural analysis, although the used ligand was the same in each reaction. Surprisingly, all of the coordination modes of the H6TTHA ligand in this work are first discovered. Furthermore, the photoluminescent results showed that these compounds displayed high-sensitivity luminescent sensing functions for nitrobenzene. Additionally, the surface photovoltage spectroscopy and electric-field-induced surface photovoltage spectroscopy showed that compounds 1-3 could behave as p-type semiconductors.

  2. Nano semiconducting materials

    CERN Document Server

    Saravanan, R

    2016-01-01

    The main focus of the present book is the characterization of a number of nano-semiconducting materials, using such techniques as powder X-ray diffraction, UV-visible spectrophotometry, Raman spectrometry, scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometry. The materials studied include ZnS, TiO2, NiO, Ga doped ZnO, Mn doped SnO2, Mn doped CeO2 and Mn doped ZrO2.

  3. P -type transparent conducting oxides

    International Nuclear Information System (INIS)

    Zhang, Kelvin H L; Xi, Kai; Blamire, Mark G; Egdell, Russell G

    2016-01-01

    Transparent conducting oxides constitute a unique class of materials combining properties of electrical conductivity and optical transparency in a single material. They are needed for a wide range of applications including solar cells, flat panel displays, touch screens, light emitting diodes and transparent electronics. Most of the commercially available TCOs are n -type, such as Sn doped In 2 O 3 , Al doped ZnO, and F doped SnO 2 . However, the development of efficient p -type TCOs remains an outstanding challenge. This challenge is thought to be due to the localized nature of the O 2 p derived valence band which leads to difficulty in introducing shallow acceptors and large hole effective masses. In 1997 Hosono and co-workers (1997 Nature 389 939) proposed the concept of ‘chemical modulation of the valence band’ to mitigate this problem using hybridization of O 2 p orbitals with close-shell Cu 3 d 10 orbitals. This work has sparked tremendous interest in designing p -TCO materials together with deep understanding the underlying materials physics. In this article, we will provide a comprehensive review on traditional and recently emergent p -TCOs, including Cu + -based delafossites, layered oxychalcogenides, nd 6 spinel oxides, Cr 3+ -based oxides (3 d 3 ) and post-transition metal oxides with lone pair state (ns 2 ). We will focus our discussions on the basic materials physics of these materials in terms of electronic structures, doping and defect properties for p -type conductivity and optical properties. Device applications based on p -TCOs for transparent p – n junctions will also be briefly discussed. (topical review)

  4. P-type Oxide Semiconductors for Transparent & Energy Efficient Electronics

    KAUST Repository

    Wang, Zhenwei

    2018-03-11

    Emerging transparent semiconducting oxide (TSO) materials have achieved their initial commercial success in the display industry. Due to the advanced electrical performance, TSOs have been adopted either to improve the performance of traditional displays or to demonstrate the novel transparent and flexible displays. However, due to the lack of feasible p-type TSOs, the applications of TSOs is limited to unipolar (n-type TSOs) based devices. Compared with the prosperous n-type TSOs, the performance of p-type counterparts is lag behind. However, after years of discovery, several p-type TSOs are confirmed with promising performance, for example, tin monoxide (SnO). By using p-type SnO, excellent transistor field-effect mobility of 6.7 cm2 V-1 s-1 has been achieved. Motivated by this encouraging performance, this dissertation is devoted to further evaluate the feasibility of integrating p-type SnO in p-n junctions and complementary metal oxide semiconductor (CMOS) devices. CMOS inverters are fabricated using p-type SnO and in-situ formed n-type tin dioxide (SnO2). The semiconductors are simultaneously sputtered, which simplifies the process of CMOS inverters. The in-situ formation of SnO2 phase is achieved by selectively sputtering additional capping layer, which serves as oxygen source and helps to balance the process temperature for both types of semiconductors. Oxides based p-n junctions are demonstrated between p-type SnO and n-type SnO2 by magnetron sputtering method. Diode operating ideality factor of 3.4 and rectification ratio of 103 are achieved. A large temperature induced knee voltage shift of 20 mV oC-1 is observed, and explained by the large band gap and shallow states in SnO, which allows minor adjustment of band structure in response to the temperature change. Finally, p-type SnO is used to demonstrating the hybrid van der Waals heterojunctions (vdWHs) with two-dimensional molybdenum disulfide (2D MoS2) by mechanical exfoliation. The hybrid vdWHs show

  5. Diamond semiconducting devices

    International Nuclear Information System (INIS)

    Polowczyk, M.; Klugmann, E.

    1999-01-01

    Many efforts to apply the semiconducting diamond for construction of electronic elements: resistors, thermistors, photoresistors, piezoresistors, hallotrons, pn diodes, Schottky diodes, IMPATT diodes, npn transistor, MESFETs and MISFETs are reviewed. Considering the possibilities of acceptor and donor doping, electrical resistivity and thermal conductivity of diamond as well as high electric-field breakdown points, that diamond devices could be used at about 30-times higher frequency and more then 8200 times power than silicon devices. Except that, due to high heat resistant of diamond, it is concluded that diamond devices can be used in environment at high temperature, range of 600 o C. (author)

  6. Intermetallic semiconducting films

    CERN Document Server

    Wieder, H H

    1970-01-01

    Intermetallic Semiconducting Films introduces the physics and technology of AшВv compound films. This material is a type of a polycrystalline semiconductor that is used for galvanomagnetic device applications. Such material has a high electron mobility that is ideal for generators and magnetoresistors. The book discusses the available references on the preparation and identification of the material. An assessment of its device applications and other possible use is also enumerated. The book describes the structures and physical parts of different films. A section of the book covers the three t

  7. Effect of gate dielectrics on the performance of p-type Cu2O TFTs processed at room temperature

    KAUST Repository

    Al-Jawhari, Hala A.

    2013-12-01

    Single-phase Cu2O films with p-type semiconducting properties were successfully deposited by reactive DC magnetron sputtering at room temperature followed by post annealing process at 200°C. Subsequently, such films were used to fabricate bottom gate p-channel Cu2O thin film transistors (TFTs). The effect of using high-κ SrTiO3 (STO) as a gate dielectric on the Cu2O TFT performance was investigated. The results were then compared to our baseline process which uses a 220 nm aluminum titanium oxide (ATO) dielectric deposited on a glass substrate coated with a 200 nm indium tin oxide (ITO) gate electrode. We found that with a 150 nm thick STO, the Cu2O TFTs exhibited a p-type behavior with a field-effect mobility of 0.54 cm2.V-1.s-1, an on/off ratio of around 44, threshold voltage equaling -0.62 V and a sub threshold swing of 1.64 V/dec. These values were obtained at a low operating voltage of -2V. The advantages of using STO as a gate dielectric relative to ATO are discussed. © (2014) Trans Tech Publications, Switzerland.

  8. Semiconducting III-V compounds

    CERN Document Server

    Hilsum, C; Henisch, Heinz R

    1961-01-01

    Semiconducting III-V Compounds deals with the properties of III-V compounds as a family of semiconducting crystals and relates these compounds to the monatomic semiconductors silicon and germanium. Emphasis is placed on physical processes that are peculiar to III-V compounds, particularly those that combine boron, aluminum, gallium, and indium with phosphorus, arsenic, and antimony (for example, indium antimonide, indium arsenide, gallium antimonide, and gallium arsenide).Comprised of eight chapters, this book begins with an assessment of the crystal structure and binding of III-V compounds, f

  9. Piezoresistance in p-type silicon revisited

    DEFF Research Database (Denmark)

    Richter, Jacob; Pedersen, Jesper; Brandbyge, Mads

    2008-01-01

    We calculate the shear piezocoefficient pi44 in p-type Si with a 6×6 k·p Hamiltonian model using the Boltzmann transport equation in the relaxation-time approximation. Furthermore, we fabricate and characterize p-type silicon piezoresistors embedded in a (001) silicon substrate. We find...... to experiments. Finally, we present a fitting function of temperature and acceptor density to the 6×6 model that can be used to predict the piezoresistance effect in p-type silicon. ©2008 American Institute of Physics...... that the relaxation-time model needs to include all scattering mechanisms in order to obtain correct temperature and acceptor density dependencies. The k·p results are compared to results obtained using a recent tight-binding (TB) model. The magnitude of the pi44 piezocoefficient obtained from the TB model...

  10. Electronic characteristics of p-type transparent SnO monolayer with high carrier mobility

    International Nuclear Information System (INIS)

    Du, Juan; Xia, Congxin; Liu, Yaming; Li, Xueping; Peng, Yuting; Wei, Shuyi

    2017-01-01

    Graphical abstract: SnO monolayer is a p-type transparent semiconducting oxide with high hole mobility (∼641 cm 2 V −1 s −1 ), which is much higher than that of MoS 2 monolayer, which indicate that it can be a promising candidate for high-performance nanoelectronic devices. Display Omitted - Highlights: • SnO monolayer is a p-type transparent semiconducting oxide. • The transparent properties can be still maintained under the strain 8%. • It has a high hole mobility (∼641 cm 2 V −1 s −1 ), which is higher than that of MoS 2 monolayer. - Abstract: More recently, two-dimensional (2D) SnO nanosheets are attaching great attention due to its excellent carrier mobility and transparent characteristics. Here, the stability, electronic structures and carrier mobility of SnO monolayer are investigated by using first-principles calculations. The calculations of the phonon dispersion spectra indicate that SnO monolayer is dynamically stable. Moreover, the band gap values are decreased from 3.93 eV to 2.75 eV when the tensile strain is applied from 0% to 12%. Interestingly, SnO monolayer is a p-type transparent semiconducting oxide with hole mobility of 641 cm 2 V −1 s −1 , which is much higher than that of MoS 2 monolayer. These findings make SnO monolayer becomes a promising 2D material for applications in nanoelectronic devices.

  11. Electronic characteristics of p-type transparent SnO monolayer with high carrier mobility

    Energy Technology Data Exchange (ETDEWEB)

    Du, Juan [College of Physics and Materials Science, Henan Normal University, Xinxiang, Henan 453007 (China); Xia, Congxin, E-mail: xiacongxin@htu.edu.cn [College of Physics and Materials Science, Henan Normal University, Xinxiang, Henan 453007 (China); Liu, Yaming [Henan Institute of Science and Technology, Xinxiang 453003 (China); Li, Xueping [College of Physics and Materials Science, Henan Normal University, Xinxiang, Henan 453007 (China); Peng, Yuting [Department of Physics, University of Texas at Arlington, TX 76019 (United States); Wei, Shuyi [College of Physics and Materials Science, Henan Normal University, Xinxiang, Henan 453007 (China)

    2017-04-15

    Graphical abstract: SnO monolayer is a p-type transparent semiconducting oxide with high hole mobility (∼641 cm{sup 2} V{sup −1} s{sup −1}), which is much higher than that of MoS{sub 2} monolayer, which indicate that it can be a promising candidate for high-performance nanoelectronic devices. Display Omitted - Highlights: • SnO monolayer is a p-type transparent semiconducting oxide. • The transparent properties can be still maintained under the strain 8%. • It has a high hole mobility (∼641 cm{sup 2} V{sup −1} s{sup −1}), which is higher than that of MoS{sub 2} monolayer. - Abstract: More recently, two-dimensional (2D) SnO nanosheets are attaching great attention due to its excellent carrier mobility and transparent characteristics. Here, the stability, electronic structures and carrier mobility of SnO monolayer are investigated by using first-principles calculations. The calculations of the phonon dispersion spectra indicate that SnO monolayer is dynamically stable. Moreover, the band gap values are decreased from 3.93 eV to 2.75 eV when the tensile strain is applied from 0% to 12%. Interestingly, SnO monolayer is a p-type transparent semiconducting oxide with hole mobility of 641 cm{sup 2} V{sup −1} s{sup −1}, which is much higher than that of MoS{sub 2} monolayer. These findings make SnO monolayer becomes a promising 2D material for applications in nanoelectronic devices.

  12. Evolution of plant P-type ATPases

    Directory of Open Access Journals (Sweden)

    Christian N.S. Pedersen

    2012-02-01

    Full Text Available Five organisms having completely sequenced genomes and belonging to all major branches of green plants (Viridiplantae were analyzed with respect to their content of P-type ATPases encoding genes. These were the chlorophytes Ostreococcus tauria and Chlamydomonas reinhardtii, and the streptophytes Physcomitrella patens (a moss, Selaginella moellendorffii (a primitive vascular plant, and Arabidopsis thaliana (a model flowering plant. Each organism contained sequences for all five subfamilies of P-type ATPases. Our analysis demonstrates when specific subgroups of P-type ATPases disappeared in the evolution of Angiosperms. Na/K-pump related P2C ATPases were lost with the evolution of streptophytes whereas Na+ or K+ pumping P2D ATPases and secretory pathway Ca2+-ATPases remained until mosses. An N-terminally located calmodulin binding domain in P2B ATPases can only be detected in pumps from Streptophytae, whereas, like in animals, a C-terminally localized calmodulin binding domain might be present in chlorophyte P2B Ca2+-ATPases. Chlorophyte genomes encode P3A ATPases resembling protist plasma membrane H+-ATPases and a C-terminal regulatory domain is missing. The complete inventory of P-type ATPases in the major branches of Viridiplantae is an important starting point for elucidating the evolution in plants of these important pumps.

  13. P-type silicon drift detectors

    International Nuclear Information System (INIS)

    Walton, J.T.; Krieger, B.; Krofcheck, D.; O'Donnell, R.; Odyniec, G.; Partlan, M.D.; Wang, N.W.

    1995-06-01

    Preliminary results on 16 CM 2 , position-sensitive silicon drift detectors, fabricated for the first time on p-type silicon substrates, are presented. The detectors were designed, fabricated, and tested recently at LBL and show interesting properties which make them attractive for use in future physics experiments. A pulse count rate of approximately 8 x l0 6 s -1 is demonstrated by the p-type silicon drift detectors. This count rate estimate is derived by measuring simultaneous tracks produced by a laser and photolithographic mask collimator that generates double tracks separated by 50 μm to 1200 μm. A new method of using ion-implanted polysilicon to produce precise valued bias resistors on the silicon drift detectors is also discussed

  14. Semiconducting silicon nanowires for biomedical applications

    CERN Document Server

    Coffer, JL

    2014-01-01

    Biomedical applications have benefited greatly from the increasing interest and research into semiconducting silicon nanowires. Semiconducting Silicon Nanowires for Biomedical Applications reviews the fabrication, properties, and applications of this emerging material. The book begins by reviewing the basics, as well as the growth, characterization, biocompatibility, and surface modification, of semiconducting silicon nanowires. It goes on to focus on silicon nanowires for tissue engineering and delivery applications, including cellular binding and internalization, orthopedic tissue scaffol

  15. Ohmic contacts to semiconducting diamond

    Science.gov (United States)

    Zeidler, James R.; Taylor, M. J.; Zeisse, Carl R.; Hewett, C. A.; Delahoussaye, Paul R.

    1990-10-01

    Work was carried out to improve the electron beam evaporation system in order to achieve better deposited films. The basic system is an ion pumped vacuum chamber, with a three-hearth, single-gun e-beam evaporator. Four improvements were made to the system. The system was thoroughly cleaned and new ion pump elements, an e-gun beam adjust unit, and a more accurate crystal monitor were installed. The system now has a base pressure of 3 X 10(exp -9) Torr, and can easily deposit high-melting-temperature metals such as Ta with an accurately controlled thickness. Improved shadow masks were also fabricated for better alignment and control of corner contacts for electrical transport measurements. Appendices include: A Thermally Activated Solid State Reaction Process for Fabricating Ohmic Contacts to Semiconducting Diamond; Tantalum Ohmic Contacts to Diamond by a Solid State Reaction Process; Metallization of Semiconducting Diamond: Mo, Mo/Au, and Mo/Ni/Au; Specific Contact Resistance Measurements of Ohmic Contracts to Diamond; and Electrical Activation of Boron Implanted into Diamond.

  16. An investigation of semiconducting behavior in the minority spin of Co2CrZ (Z = Ga, Ge, As): LSDA and LSDA + U method

    International Nuclear Information System (INIS)

    Rai, D.P.; Thapa, R.K.

    2012-01-01

    Highlights: ► Volume optimization was done to find the theoretical lattice parameters. ► LSDA was performed to calculate electronic and magnetic properties of Co 2 CrZ. ► The result shows the half-metal ferromagnetic behavior of Co 2 CrGa and Co 2 CrGe. ► Co 2 CrAs fails to give HMF within LSDA thus treated with LSDA + U, to obtain HMF. - Abstract: We have calculated the electronic and magnetic properties of 3d transition metal based full Heusler compounds Co 2 CrZ (Z = Ga, Ge, As), by using full potential linearized augmented plane wave (FP-LAPW) method. The calculated density of states (DOS) and band structure for Co 2 CrZ shows the existence of band gap in their minority-spin channel. The respective energy gaps of Co 2 CrGe and Co 2 CrGa are 0.24 and 0.38 eV with their Fermi energies (E F s) lie exactly at the gap. The compound Co 2 CrAs when treated with local spin density approximation (LSDA) does not show half metallic ferromagnetism (HMF) even though there exist a gap this is because the E F does not lie at the middle of the gap. We have considered Co 2 CrAs as strongly correlated system as Cr-d states at E F are strongly localized thus the system was treated in terms of the LSDA + U. The total magnetic moment of Co 2 CrAs was found to be an exact integer value 5.00 μ B within LSDA + U. We have also found that the total magnetic moments increase as the Z goes from Ga to As.

  17. Electroforming-free resistive switching memory effect in transparent p-type tin monoxide

    KAUST Repository

    Hota, M. K.; Caraveo-Frescas, J. A.; McLachlan, M. A.; Alshareef, Husam N.

    2014-01-01

    We report reproducible low bias bipolar resistive switching behavior in p-type SnO thin film devices without extra electroforming steps. The experimental results show a stable resistance ratio of more than 100 times, switching cycling performance up

  18. Ruddlesden-Popper compounds (SrO)(LaFeO3)n (n = 1 and 2) as p-type semiconductors for photocatalytic hydrogen production

    International Nuclear Information System (INIS)

    Chen, Hongmei; Sun, Xiaoqin; Xu, Xiaoxiang

    2017-01-01

    Graphical abstract: Two layered ferrites LaSrFeO 4 and La 2 SrFe 2 O 7 have been investigated which demonstrate interesting p-type semconductivity and efficient hydrogen production from water. Display Omitted -- Abstract: Here we report two Ruddlesden-Popper type ferrite perovskites (SrO)(LaFeO 3 ) n (n = 1 and 2) which demonstrate p-type semiconductivity. Their crystal structure, optical absorption and other physicochemical properties have been systematically explored. Our results show that both ferrites crystallize in tetragonal symmetry with structural lamination along c axis. Efficient photocatalytic hydrogen production has been achieved for both samples under full range and visible light illumination. Better performance is noticed for LaSrFeO 4 with apparent quantum efficiency approaches 0.31% and 0.19% under full range and visible light illumination, respectively. The p-type semiconductivity is verified by their cathodic photocurrent as well as negative Mott-Schottky slop during Photoelectrochemical measurement. The relative lower activity for La 2 SrFe 2 O 7 compared to LaSrFeO 4 is likely due to its higher defect concentration which facilitates charge recombination. Both compounds exhibit anisotropic phenomenon for charge migrations according to theoretical calculations. Their p-type semiconductivity, strong visible light absorption, chemical inertness and high abundance of constituent elements signify promising applications in the field of solar energy conversion and optoelectronics.

  19. Efficient Naphthalenediimide-Based Hole Semiconducting Polymer with Vinylene Linkers between Donor and Acceptor Units

    KAUST Repository

    Zhang, Lei

    2016-11-04

    We demonstrate a new method to reverse the polarity and charge transport behavior of naphthalenediimide (NDI)-based copolymers by inserting a vinylene linker between the donor and acceptor units. The vinylene linkers minimize the intrinsic steric congestion between the NDI and thiophene moieties to prompt backbone planarity. The polymers with vinylene linkers exhibit electron n-channel transport characteristics under vacuum, similar to the benchmark polymer, P(NDI2OD-T2). To our surprise, when the polymers are measured in air, the dominant carrier type switches from n- to p-type and yield hole mobilities up to 0.45 cm(2) s(-1) with hole to electron mobility ratio of three (mu(h)/mu(e), similar to 3), which indicates that the hole density in the active layer can be significantly increased by exposure to air. This increase is consistent with the intrinsic more delocalized nature of the highest occupied molecular orbital of the charged vinylene polymer, as estimated by density functional theory (DFT) calculations, which facilitates hole transport within the polymer chains. This is the first demonstration of an efficient NDI-based hole semiconducting polymer, which will enable new developments in all-polymer solar cells, complementary circuits, and dopable polymers for use in thermoelectrics.

  20. Efficient Naphthalenediimide-Based Hole Semiconducting Polymer with Vinylene Linkers between Donor and Acceptor Units

    KAUST Repository

    Zhang, Lei; Rose, Bradley Daniel; Liu, Yao; Nahid, Masrur M.; Gann, Eliot; Ly, Jack; Zhao, Wei; Rosa, Stephen J.; Russell, Thomas P.; Facchetti, Antonio; McNei, Christopher R.; Bredas, Jean-Luc; Briseno, Alejandro L.

    2016-01-01

    We demonstrate a new method to reverse the polarity and charge transport behavior of naphthalenediimide (NDI)-based copolymers by inserting a vinylene linker between the donor and acceptor units. The vinylene linkers minimize the intrinsic steric congestion between the NDI and thiophene moieties to prompt backbone planarity. The polymers with vinylene linkers exhibit electron n-channel transport characteristics under vacuum, similar to the benchmark polymer, P(NDI2OD-T2). To our surprise, when the polymers are measured in air, the dominant carrier type switches from n- to p-type and yield hole mobilities up to 0.45 cm(2) s(-1) with hole to electron mobility ratio of three (mu(h)/mu(e), similar to 3), which indicates that the hole density in the active layer can be significantly increased by exposure to air. This increase is consistent with the intrinsic more delocalized nature of the highest occupied molecular orbital of the charged vinylene polymer, as estimated by density functional theory (DFT) calculations, which facilitates hole transport within the polymer chains. This is the first demonstration of an efficient NDI-based hole semiconducting polymer, which will enable new developments in all-polymer solar cells, complementary circuits, and dopable polymers for use in thermoelectrics.

  1. Assembly of ordered carbon shells on semiconducting nanomaterials

    Science.gov (United States)

    Sutter, Eli Anguelova; Sutter, Peter Werner

    2012-10-02

    In some embodiments of the invention, encapsulated semiconducting nanomaterials are described. In certain embodiments the nanostructures described are semiconducting nanomaterials encapsulated with ordered carbon shells. In some aspects a method for producing encapsulated semiconducting nanomaterials is disclosed. In some embodiments applications of encapsulated semiconducting nanomaterials are described.

  2. Imperceptible and Ultraflexible p-Type Transistors and Macroelectronics Based on Carbon Nanotubes.

    Science.gov (United States)

    Cao, Xuan; Cao, Yu; Zhou, Chongwu

    2016-01-26

    Flexible thin-film transistors based on semiconducting single-wall carbon nanotubes are promising for flexible digital circuits, artificial skins, radio frequency devices, active-matrix-based displays, and sensors due to the outstanding electrical properties and intrinsic mechanical strength of carbon nanotubes. Nevertheless, previous research effort only led to nanotube thin-film transistors with the smallest bending radius down to 1 mm. In this paper, we have realized the full potential of carbon nanotubes by making ultraflexible and imperceptible p-type transistors and circuits with a bending radius down to 40 μm. In addition, the resulted transistors show mobility up to 12.04 cm(2) V(-1) S(-1), high on-off ratio (∼10(6)), ultralight weight (transistors and circuits have great potential to work as indispensable components for ultraflexible complementary electronics.

  3. Controlled p-type to n-type conductivity transformation in NiO thin films by ultraviolet-laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Pranav; Dutta, Titas; Mal, Siddhartha; Narayan, Jagdish [Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27606 (United States)

    2012-01-01

    We report the systematic changes in structural, electrical, and optical properties of NiO thin films on c-sapphire introduced by nanosecond ultraviolet excimer laser pulses. Epitaxial nature of as deposited NiO was determined by x-ray diffraction phi scans and transmission electron microscopy (TEM) and it was established that NiO film growth takes place with twin domains on sapphire where two types of domains have 60 deg. in-plane rotation with respect to each other about the [111] growth direction. We determined that at pulsed laser energy density of 0.275 J/cm{sup 2}, NiO films exhibited conversion from p-type semiconducting to n-type conductive behavior with three orders of magnitude decrease in resistivity, while maintaining its cubic crystal structure and good epitaxial relationship. Our TEM and electron-energy-loss spectroscopy studies conclusively ruled out the presence of any Ni clustering or precipitation due to the laser treatment. The laser-induced n-type carrier transport and conductivity enhancement were shown to be reversible through subsequent thermal annealing in oxygen. This change in conductivity behavior was correlated with the nonequilibrium concentration of laser induced Ni{sup 0}-like defect states.

  4. Two-dimensional ferromagnet/semiconductor transition metal dichalcogenide contacts: p-type Schottky barrier and spin-injection control

    KAUST Repository

    Gan, Liyong; Cheng, Yingchun; Schwingenschlö gl, Udo; Zhang, Qingyun

    2013-01-01

    We study the ferromagnet/semiconductor contacts formed by transition metal dichalcogenide monolayers, focusing on semiconducting MoS2 and WS2 and ferromagnetic VS2. We investigate the degree of p-type doping and demonstrate tuning of the Schottky barrier height by vertical compressive pressure. An analytical model is presented for the barrier heights that accurately describes the numerical findings and is expected to be of general validity for all transition metal dichalcogenide metal/semiconductor contacts. Furthermore, magnetic proximity effects induce a 100% spin polarization at the Fermi level in the semiconductor where the spin splitting increases up to 0.70 eV for increasing pressure.

  5. Two-dimensional ferromagnet/semiconductor transition metal dichalcogenide contacts: p-type Schottky barrier and spin-injection control

    KAUST Repository

    Gan, Liyong

    2013-09-26

    We study the ferromagnet/semiconductor contacts formed by transition metal dichalcogenide monolayers, focusing on semiconducting MoS2 and WS2 and ferromagnetic VS2. We investigate the degree of p-type doping and demonstrate tuning of the Schottky barrier height by vertical compressive pressure. An analytical model is presented for the barrier heights that accurately describes the numerical findings and is expected to be of general validity for all transition metal dichalcogenide metal/semiconductor contacts. Furthermore, magnetic proximity effects induce a 100% spin polarization at the Fermi level in the semiconductor where the spin splitting increases up to 0.70 eV for increasing pressure.

  6. P-type Oxide Semiconductors for Transparent & Energy Efficient Electronics

    KAUST Repository

    Wang, Zhenwei

    2018-01-01

    , the performance of p-type counterparts is lag behind. However, after years of discovery, several p-type TSOs are confirmed with promising performance, for example, tin monoxide (SnO). By using p-type SnO, excellent transistor field-effect mobility of 6.7 cm2 V-1 s

  7. Fabrication of p-type porous GaN on silicon and epitaxial GaN

    OpenAIRE

    Bilousov, Oleksandr V.; Geaney, Hugh; Carvajal, Joan J.; Zubialevich, Vitaly Z.; Parbrook, Peter J.; Giguere, A.; Drouin, D.; Diaz, Francesc; Aguilo, Magdalena; O'Dwyer, Colm

    2013-01-01

    Porous GaN layers are grown on silicon from gold or platinum catalyst seed layers, and self-catalyzed on epitaxial GaN films on sapphire. Using a Mg-based precursor, we demonstrate p-type doping of the porous GaN. Electrical measurements for p-type GaN on Si show Ohmic and Schottky behavior from gold and platinum seeded GaN, respectively. Ohmicity is attributed to the formation of a Ga2Au intermetallic. Porous p-type GaN was also achieved on epitaxial n-GaN on sapphire, and transport measurem...

  8. Realization of N-Type Semiconducting of Phosphorene through Surface Metal Doping and Work Function Study

    Directory of Open Access Journals (Sweden)

    Haocheng Sun

    2018-01-01

    Full Text Available Phosphorene becomes an important member of the layered nanomaterials since its discovery for the fabrication of nanodevices. In the experiments, pristine phosphorene shows p-type semiconducting with no exception. To reach its full capability, n-type semiconducting is a necessity. Here, we report the electronic structure engineering of phosphorene by surface metal atom doping. Five metal elements, Cu, Ag, Au, Li, and Na, have been considered which could form stable adsorption on phosphorene. These elements show patterns in their electron configuration with one valence electron in their outermost s-orbital. Among three group 11 elements, Cu can induce n-type degenerate semiconducting, while Ag and Au can only introduce localized impurity states. The distinct ability of Cu, compared to Ag and Au, is mainly attributed to the electronegativity. Cu has smaller electronegativity and thus denotes its electron to phosphorene, upshifting the Fermi level towards conduction band, resulting in n-type semiconducting. Ag and Au have larger electronegativity and hardly transfer electrons to phosphorene. Parallel studies of Li and Na doping support these findings. In addition, Cu doping effectively regulates the work function of phosphorene, which gradually decreases upon increasing Cu concentration. It is also interesting that Au can hardly change the work function of phosphorene.

  9. Development of p-type amorphous Cu{sub 1−x}B{sub x}O{sub 2−δ} thin films and fabrication of pn hetero junction

    Energy Technology Data Exchange (ETDEWEB)

    Sanal, K.C., E-mail: sanalcusat@gmail.com [Nanophotonic and Optoelectronic Devices Laboratory, Department of Physics, Cochin University of Science and Technology, Kerala 682022 (India); Inter University Center for Nanomaterials and Devices (IUCND), Cochin University of Science and Technology, Kerala 682022 (India); Center for Advanced Materials, Cochin University of Science and Technology, Kerala 682022 (India); Jayaraj, M.K., E-mail: mkj@cusat.ac.in [Nanophotonic and Optoelectronic Devices Laboratory, Department of Physics, Cochin University of Science and Technology, Kerala 682022 (India); Center for Advanced Materials, Cochin University of Science and Technology, Kerala 682022 (India)

    2014-07-01

    Highlights: • Growth of p-type semiconducting amorphous Cu{sub 1−x}B{sub x}O{sub 2−δ} thin films by co-sputtering. • Atomic percentage of Cu{sub 1−x}B{sub x}O{sub 2−δ} thin films from the XPS analysis. • Variation of bandgap with boron concentration in Cu{sub 1−x}B{sub x}O{sub 2−δ} thin films. • Demonstration of p–n hetero junctions fabricated in the structure n-Si/p-Cu{sub 1−x}B{sub x}O{sub 2−δ}/Au. - Abstract: Transparent conducting amorphous p type Cu{sub 1−x}B{sub x}O{sub 2−δ} thin films were grown by RF magnetron co-sputtering at room temperature, using copper and boron targets in oxygen atmosphere. The structural, electrical as well as optical properties were studied. Composition of the films was analyzed by XPS. Amorphous structure of as deposited films was confirmed by GXRD. Surface morphology of the films was analyzed by AFM studies. p-Type nature and concentration of carriers were investigated by Hall effect measurement. Band gap of the films was found to increase with the atomic content of boron in the film. A p–n hetero junction using p-type Cu{sub 1−x}B{sub x}O{sub 2−δ} and n-type silicon was fabricated in the structure n-Si/p-Cu{sub 1−x}B{sub x}O{sub 2−δ}/Au which showed rectifying behavior. As deposited amorphous Cu{sub 1−x}B{sub x}O{sub 2−δ} thin films with lower carrier concentration can be used as a channel layer for thin film transistors.

  10. Semiconducting compounds and devices incorporating same

    Science.gov (United States)

    Marks, Tobin J.; Facchetti, Antonio; Boudreault, Pierre-Luc; Miyauchi, Hiroyuki

    2016-01-19

    Disclosed are molecular and polymeric compounds having desirable properties as semiconducting materials. Such compounds can exhibit desirable electronic properties and possess processing advantages including solution-processability and/or good stability. Organic transistor and photovoltaic devices incorporating the present compounds as the active layer exhibit good device performance.

  11. On Allosteric Modulation of P-Type Cu+-ATPases

    DEFF Research Database (Denmark)

    Mattle, Daniel; Sitsel, Oleg; Autzen, Henriette Elisabeth

    2013-01-01

    P-type ATPases perform active transport of various compounds across biological membranes and are crucial for ion homeostasis and the asymmetric composition of lipid bilayers. Although their functional cycle share principles of phosphoenzyme intermediates, P-type ATPases also show subclass...... of intramembranous Cu+ binding, and we suggest an alternative role for the proposed second site in copper translocation and proton exchange. The class-specific features demonstrate that topological diversity in P-type ATPases may tune a general energy coupling scheme to the translocation of compounds with remarkably...

  12. Theory of Persistent, P-Type, Metallic Conduction in C-GeTe

    National Research Council Canada - National Science Library

    Edwards, Arthur H; Pineda, Andrew C; Schultz, Peter A; Martin, Marcus G; Thompson, Aidan P; Hjalmarson, Harold P

    2005-01-01

    .... However, it always displays p-type metallic conduction. This behavior is also observed in other chalcogenide materials, including Ge2Sb2Te5, commonly used for optically and electrically switched, non-volatile memory, and so is or great interest...

  13. Transparent p-type SnO nanowires with unprecedented hole mobility among oxide semiconductors

    KAUST Repository

    Caraveo-Frescas, J. A.; Alshareef, Husam N.

    2013-01-01

    p-type tin monoxide (SnO) nanowire field-effect transistors with stable enhancement mode behavior and record performance are demonstrated at 160 °C. The nanowire transistors exhibit the highest field-effect hole mobility (10.83 cm2 V−1 s−1) of any p

  14. Ohmic Contacts to P-Type SiC

    National Research Council Canada - National Science Library

    Crofton, John

    2000-01-01

    Alloys of aluminum (Al) have previously been used as ohmic contacts to p-type SiC, however the characteristics and performance of these contacts is drastically affected by the type and composition of the Al alloy...

  15. Synthesis and Applications of Semiconducting Graphene

    Directory of Open Access Journals (Sweden)

    Shahrima Maharubin

    2016-01-01

    Full Text Available Semimetal-to-semiconductor transition in graphene can bestow graphene with numerous novel and enhanced structural, electrical, optical, and physicochemical characteristics. The scope of graphene and its prospective for an array of implications could be significantly outspread by this transition. In consideration of the recent advancements of semiconducting graphene, this article widely reviews the properties, production, and developing operations of this emergent material. The comparisons among the benefits and difficulties of current methods are made, intending to offer evidences to develop novel and scalable synthesis approaches. The emphasis is on the properties and applications resulting from various conversion methods (doping, controlled reduction, and functionalization, expecting to get improved knowledge on semiconducting graphene materials. Intending to motivate further efficient implications, the mechanisms leading to their beneficial usages for energy conversion and storage are also emphasized.

  16. Controllable synthesis of p-type Cu{sub 2}S nanowires for self-driven NIR photodetector application

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Chun-Yan, E-mail: cywu@hfut.edu.cn; Pan, Zhi-Qiang; Liu, Zhu; Wang, You-Yi [Hefei University of Technology, School of Electronic Science and Applied Physics (China); Liang, Feng-Xia [Hefei University of Technology, School of Materials Science and Engineering and Anhui Provincial Key Laboratory of Advanced Functional Materials and Devices (China); Yu, Yong-Qiang; Wang, Li; Luo, Lin-Bao, E-mail: luolb@hfut.edu.cn [Hefei University of Technology, School of Electronic Science and Applied Physics (China)

    2017-02-15

    Face-centered cubic Cu{sub 2}S nanowires with length of up to 50 μm and diameters in the range of 100–500 nm are synthesized on Si substrates through the chemical vapor deposition method using a mixed gas of Ar and H{sub 2} as the carrier gas under a chamber pressure of about 700 Torr. It was found that the growth of quasi 1D nanostructure followed a typical vapor-liquid-solid (VLS) mechanism in which the element Cu was reduced by H{sub 2} as the catalyst. The as-synthesized Cu{sub 2}S nanowires exhibited typical p-type semiconducting characteristics with a conductivity of about 600 S cm{sup −1} and a hole mobility (μ{sub h}) of about 72 cm{sup 2} V{sup −1} s{sup −1}. Further study reveals that p-Cu{sub 2}S nanowires/n-Si heterojunction exhibits distinct rectifying characteristics with a turn-on voltage of ~0.6 V and a rectification ratio of ~300 at ±1 V in the dark and a pronounced photovoltaic behavior with an open circuit voltage (V{sub oc}) of 0.09 V and a short circuit current (I{sub sc}) of 65 nA when illuminated by the NIR light (790 nm, 0.35 mW cm{sup −1}), giving rise to a responsivity (R) about 0.8 mA W{sup −1} and specific detectivity (D*) 6.7 × 10{sup 10} cm Hz{sup 1/2} W{sup −1} at zero bias, which suggests the potential of as-synthesized Cu{sub 2}S nanowires applied in the field of self-driven NIR photodetector.

  17. Hydrothermal synthetic strategies of inorganic semiconducting nanostructures.

    Science.gov (United States)

    Shi, Weidong; Song, Shuyan; Zhang, Hongjie

    2013-07-07

    Because of their unique chemical and physical properties, inorganic semiconducting nanostructures have gradually played a pivotal role in a variety of research fields, including electronics, chemical reactivity, energy conversion, and optics. A major feature of these nanostructures is the quantum confinement effect, which strongly depends on their size, shape, crystal structure and polydispersity. Among all developed synthetic methods, the hydrothermal method based on a water system has attracted more and more attention because of its outstanding advantages, such as high yield, simple manipulation, easy control, uniform products, lower air pollution, low energy consumption and so on. Precise control over the hydrothermal synthetic conditions is a key to the success of the preparation of high-quality inorganic semiconducting nanostructures. In this review, only the representative hydrothermal synthetic strategies of inorganic semiconducting nanostructures are selected and discussed. We will introduce the four types of strategies based on exterior reaction system adjustment, namely organic additive- and template-free hydrothermal synthesis, organic additive-assisted hydrothermal synthesis, template-assisted hydrothermal synthesis and substrate-assisted hydrothermal synthesis. In addition, the two strategies based on exterior reaction environment adjustment, including microwave-assisted and magnetic field-assisted hydrothermal synthesis, will be also described. Finally, we conclude and give the future prospects of this research area.

  18. Undoped p-type GaN1-xSbx alloys: Effects of annealing

    Science.gov (United States)

    Segercrantz, N.; Baumgartner, Y.; Ting, M.; Yu, K. M.; Mao, S. S.; Sarney, W. L.; Svensson, S. P.; Walukiewicz, W.

    2016-12-01

    We report p-type behavior for undoped GaN1-xSbx alloys with x ≥ 0.06 grown by molecular beam epitaxy at low temperatures (≤400 °C). Rapid thermal annealing of the GaN1-xSbx films at temperatures >400 °C is shown to generate hole concentrations greater than 1019 cm-3, an order of magnitude higher than typical p-type GaN achieved by Mg doping. The p-type conductivity is attributed to a large upward shift of the valence band edge resulting from the band anticrossing interaction between localized Sb levels and extended states of the host matrix.

  19. Transparent p-type SnO nanowires with unprecedented hole mobility among oxide semiconductors

    KAUST Repository

    Caraveo-Frescas, J. A.

    2013-11-25

    p-type tin monoxide (SnO) nanowire field-effect transistors with stable enhancement mode behavior and record performance are demonstrated at 160 °C. The nanowire transistors exhibit the highest field-effect hole mobility (10.83 cm2 V−1 s−1) of any p-type oxide semiconductor processed at similar temperature. Compared to thin film transistors, the SnO nanowire transistors exhibit five times higher mobility and one order of magnitude lower subthreshold swing. The SnO nanowire transistors show three times lower threshold voltages (−1 V) than the best reported SnO thin film transistors and fifteen times smaller than p-type Cu 2O nanowire transistors. Gate dielectric and process temperature are critical to achieving such performance.

  20. Synthesis of p-type GaN nanowires.

    Science.gov (United States)

    Kim, Sung Wook; Park, Youn Ho; Kim, Ilsoo; Park, Tae-Eon; Kwon, Byoung Wook; Choi, Won Kook; Choi, Heon-Jin

    2013-09-21

    GaN has been utilized in optoelectronics for two decades. However, p-type doping still remains crucial for realization of high performance GaN optoelectronics. Though Mg has been used as a p-dopant, its efficiency is low due to the formation of Mg-H complexes and/or structural defects in the course of doping. As a potential alternative p-type dopant, Cu has been recognized as an acceptor impurity for GaN. Herein, we report the fabrication of Cu-doped GaN nanowires (Cu:GaN NWs) and their p-type characteristics. The NWs were grown vertically via a vapor-liquid-solid (VLS) mechanism using a Au/Ni catalyst. Electrical characterization using a nanowire-field effect transistor (NW-FET) showed that the NWs exhibited n-type characteristics. However, with further annealing, the NWs showed p-type characteristics. A homo-junction structure (consisting of annealed Cu:GaN NW/n-type GaN thin film) exhibited p-n junction characteristics. A hybrid organic light emitting diode (OLED) employing the annealed Cu:GaN NWs as a hole injection layer (HIL) also demonstrated current injected luminescence. These results suggest that Cu can be used as a p-type dopant for GaN NWs.

  1. Characterization of n and p-type ZnO thin films grown by pulsed filtered cathodic vacuum arc system

    International Nuclear Information System (INIS)

    Kavak, H.; Erdogan, E.N.; Ozsahin, I.; Esen, R.

    2010-01-01

    Full text : Semiconductor ZnO thin films with wide band gap attract much interest due to their properties such as chemical stability in hydrogen plasma, high optical transparency in the visible and nearinfrared region. Due to these properties ZnO oxide is a promising materials for electronic or optoelectronic applications such as solar cell (as an antireflecting coating and a transparent conducting material), gas sensors, surface acoustic wave devices. The purpose of this research is to improve the properties of n and p-type ZnO thin films for device applications. Polycrystalline ZnO is naturally n-type and very difficult to dope to make p-type. Therefore nowadays hardly produced p-type ZnO attracts a lot of attention. Nitrogen considered as the best dopant for p-type ZnO thin films.The transparent, conductive and very precise thickness controlled n and p-type semiconducting nanocrystalline ZnO thin films were prepared by pulsed filtered cathodic vacuum arc deposition (PFCVAD) method. Structural, optical and electrical properties of these films were investigated. And also photoluminescence properties of these films were investigated. Transparent p-type ZnO thin films were produced by oxidation of PFCVAD deposited zinc nitride. Zinc nitride thin films were deposited with various thicknesses and under different oxygen pressures on glass substrates. Zinc nitride thin films, which were deposited at room temperatures, were amorphous and the optical transmission was below 70%. For oxidation zinc nitride, the sample was annealed in air starting from 350 degrees Celsium up to 550 degrees Celsium for one hour duration. These XRD patterns imply that zinc nitride thin films converted to zinc oxide thin films with the same hexagonal crystalline structures of ZnO. The optical measurements were made for each annealing temperature and the optical transmissions of ZnO thin films were found better than 90 percent in visible range after annealing over 350 degrees Celsium. By

  2. Activities towards p-type doping of ZnO

    International Nuclear Information System (INIS)

    Brauer, G; Kuriplach, J; Ling, C C; Djurisic, A B

    2011-01-01

    Zinc oxide (ZnO) is an interesting and promising semiconductor material for many potential applications, e.g. in opto-electronics and for sensor devices. However, its p-type doping represents a challenging problem, and the physical reasons of its mostly n-type conductivity are not perfectly clear at present. Efforts to achieve p-type conductivity by ion implantation are reviewed, and ways to achieve p-type ZnO nanorods and thin films through various growth conditions are summarized. Then, issues associated with the preparation of Schottky contacts is discussed in some detail as this is a requirement of the device formation process. Finally, the possible incorporation of hydrogen and nitrogen into structural defects, which can act as trapping sites for positrons, is discussed in the context of experimental and theoretical positron results and the estimated H and N content in a variety of ZnO materials.

  3. Activities towards p-type doping of ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Brauer, G [Institut fuer Ionenstrahlphysik und Materialforschung, Forschungszentrum Dresden-Rossendorf, Postfach 510119, D-01314 Dresden (Germany); Kuriplach, J [Department of Low Temperature Physics, Charles University, V Holetovickach 2, CZ-18000 Prague (Czech Republic); Ling, C C; Djurisic, A B, E-mail: g.brauer@fzd.de [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong)

    2011-01-10

    Zinc oxide (ZnO) is an interesting and promising semiconductor material for many potential applications, e.g. in opto-electronics and for sensor devices. However, its p-type doping represents a challenging problem, and the physical reasons of its mostly n-type conductivity are not perfectly clear at present. Efforts to achieve p-type conductivity by ion implantation are reviewed, and ways to achieve p-type ZnO nanorods and thin films through various growth conditions are summarized. Then, issues associated with the preparation of Schottky contacts is discussed in some detail as this is a requirement of the device formation process. Finally, the possible incorporation of hydrogen and nitrogen into structural defects, which can act as trapping sites for positrons, is discussed in the context of experimental and theoretical positron results and the estimated H and N content in a variety of ZnO materials.

  4. Picosecond intersubband hole relaxation in p-type quantum wells

    International Nuclear Information System (INIS)

    Xu, Z.; Fauchet, P.M.; Rella, C.W.; Schwettman, H.A.

    1995-01-01

    We report the first direct measurement of the relaxation time of holes in p-type quantum wells using tunable, subpicosecond mid-infrared laser pulses in a pump-probe arrangement. The QW layers consisted of 50 In 0.5 Ga 0.5 As/Al 0.5 Ga 0.5 As periods. The In 0.5 Ga 0.5 As well was 4 nm wide and the Al 0.5 Ga 0.5 As barrier was 8 nm wide. The dopant concentration was 10 19 CM -3 which corresponds to a sheet density of 1.2 x 10 13 CM -2 . The room temperature IR spectrum showed a 50 meV wide absorption peak at 5.25 μm (220 meV). This energy agrees with the calculated n=1 heavy hole to n=1 light hole transition energy of 240 meV (150 meV for strain and 90 meV for confinement). The large absorption width results from hole-hole scattering and the difference in dispersion relations between the two subbands. The equal-wavelength pump-probe transmission measurements were performed using the Stanford free electron laser (FEL). The FEL pulses were tuned between 4 and 6 μ m and their duration was less than 1 ps. The measurements were performed as a function of temperature, pump wavelength and intensity (from 0.3 to 10 GW/cm 2 ). In all our experiments, we find an increase of transmission (decrease of absorption or bleaching) following photopumping, which recovers as a single exponential with a time constant (relaxation time) of the order of 1 picosecond. The maximum change in transmission is linear with pump 2 intensity below 1 GW/cm 2 and saturates to ∼3% with a saturation intensity I sat of 3 GW/cm 2 . As the saturation regime is entered, the relaxation time increases from 0.8 ps to 1.8 ps. This relaxation time depends on the temperature T: it increases from 0.8 ps to 1.3 ps as T decreases from 300 K to 77 K. Finally, when we tune the laser through the absorption band, the magnitude of the signal changes but its temporal behavior does not change, within the accuracy of the measurements

  5. Development and Processing of p-type Oxide Thermoelectric Materials

    DEFF Research Database (Denmark)

    Wu, NingYu; Van Nong, Ngo

    The main aim of this research is to investigate and develop well-performing p-type thermoelectric oxide materials that are sufficiently stable at high temperatures for power generating applications involving industrial processes. Presently, the challenges facing the widespread implementation...

  6. Compensation of native donor doping in ScN: Carrier concentration control and p-type ScN

    Science.gov (United States)

    Saha, Bivas; Garbrecht, Magnus; Perez-Taborda, Jaime A.; Fawey, Mohammed H.; Koh, Yee Rui; Shakouri, Ali; Martin-Gonzalez, Marisol; Hultman, Lars; Sands, Timothy D.

    2017-06-01

    Scandium nitride (ScN) is an emerging indirect bandgap rocksalt semiconductor that has attracted significant attention in recent years for its potential applications in thermoelectric energy conversion devices, as a semiconducting component in epitaxial metal/semiconductor superlattices and as a substrate material for high quality GaN growth. Due to the presence of oxygen impurities and native defects such as nitrogen vacancies, sputter-deposited ScN thin-films are highly degenerate n-type semiconductors with carrier concentrations in the (1-6) × 1020 cm-3 range. In this letter, we show that magnesium nitride (MgxNy) acts as an efficient hole dopant in ScN and reduces the n-type carrier concentration, turning ScN into a p-type semiconductor at high doping levels. Employing a combination of high-resolution X-ray diffraction, transmission electron microscopy, and room temperature optical and temperature dependent electrical measurements, we demonstrate that p-type Sc1-xMgxN thin-film alloys (a) are substitutional solid solutions without MgxNy precipitation, phase segregation, or secondary phase formation within the studied compositional region, (b) exhibit a maximum hole-concentration of 2.2 × 1020 cm-3 and a hole mobility of 21 cm2/Vs, (c) do not show any defect states inside the direct gap of ScN, thus retaining their basic electronic structure, and (d) exhibit alloy scattering dominating hole conduction at high temperatures. These results demonstrate MgxNy doped p-type ScN and compare well with our previous reports on p-type ScN with manganese nitride (MnxNy) doping.

  7. High performance p-type half-Heusler thermoelectric materials

    Science.gov (United States)

    Yu, Junjie; Xia, Kaiyang; Zhao, Xinbing; Zhu, Tiejun

    2018-03-01

    Half-Heusler compounds, which possess robust mechanical strength, good high temperature thermal stability and multifaceted physical properties, have been verified as a class of promising thermoelectric materials. During the last two decades, great progress has been made in half-Heusler thermoelectrics. In this review, we summarize some representative work of p-type half-Heusler materials, the thermoelectric performance of which has been remarkably enhanced in recent years. We introduce the features of the crystal and electronic structures of half-Heusler compounds, and successful strategies for optimizing electrical and thermal transport in the p-type RFeSb (R  =  V, Nb, Ta) and MCoSb (M  =  Ti, Zr, Hf) based systems, including band engineering, the formation of solid solutions and hierarchical phonon scattering. The outlook for future research directions of half-Heusler thermoelectrics is also presented.

  8. Superconductivity in Ti3P-type compounds

    International Nuclear Information System (INIS)

    Wills, J.O.; Hein, R.A.; Waterstrat, R.M.

    1978-01-01

    A study of 12 intermetallic A 3 B compounds which crsytallize in the tetragonal Ti 3 P-type structure has revealed five new superconductors with transition temperatures below 1 K: Zr 3 Si, Zr 3 Ge, Zr 3 P, V 3 P, and Nb 3 Ge (extrapolated from the alloy series Nb-Ge-As). In addition, two compounds, Zr 3 Sb and Ta 3 Ge, having the Ni 3 P structure type are found to be superconducting below 1 K. Within the Ti 3 P-type compounds, those with the lighter ''B'' elements in a given column of the Periodic Table have the higher transition temperatures. Critical-magnetic-field and electrical-resistivity data are reported for the superconducting Ti 2 P-type compound Nb 3 P, which permit one to estimate the Ginzburg-Landau kappa parameter and the electronic-specific-heat coefficient γ. The kappa value of 8.4 indicates that this material is type II, and the γ value of 1.3 mJ/mole K 2 for Nb 3 P is probably related to its low transition temperature relative to many A15 compounds

  9. Binary Oxide p-n Heterojunction Piezoelectric Nanogenerators with an Electrochemically Deposited High p-Type Cu2O Layer.

    Science.gov (United States)

    Baek, Seung Ki; Kwak, Sung Soo; Kim, Joo Sung; Kim, Sang Woo; Cho, Hyung Koun

    2016-08-31

    The high performance of ZnO-based piezoelectric nanogenerators (NGs) has been limited due to the potential screening from intrinsic electron carriers in ZnO. We have demonstrated a novel approach to greatly improve piezoelectric power generation by electrodepositing a high-quality p-type Cu2O layer between the piezoelectric semiconducting film and the metal electrode. The p-n heterojunction using only oxides suppresses the screening effect by forming an intrinsic depletion region, and thus sufficiently enhances the piezoelectric potential, compared to the pristine ZnO piezoelectric NG. Interestingly, a Sb-doped Cu2O layer has high mobility and low surface trap states. Thus, this doped layer is an attractive p-type material to significantly improve piezoelectric performance. Our results revealed that p-n junction NGs consisting of Au/ZnO/Cu2O/indium tin oxide with a Cu2O:Sb (cuprous oxide with a small amount of antimony) layer of sufficient thickness (3 μm) exhibit an extraordinarily high piezoelectric potential of 0.9 V and a maximum output current density of 3.1 μA/cm(2).

  10. Effects of Rh on the thermoelectric performance of the p-type Zr0.5Hf0.5Co1-xRhxSb0.99Sn0.01 half-Heusler alloys

    International Nuclear Information System (INIS)

    Maji, Pramathesh; Takas, Nathan J.; Misra, Dinesh K.; Gabrisch, Heike; Stokes, Kevin; Poudeu, Pierre F.P.

    2010-01-01

    We show that Rh substitution at the Co site in Zr 0.5 Hf 0.5 Co 1-x Rh x Sb 0.99 Sn 0.01 (0≤x≤1) half-Heusler alloys strongly reduces the thermal conductivity with a simultaneous, significant improvement of the power factor of the materials. Thermoelectric properties of hot-pressed pellets of several compositions with various Rh concentrations were investigated in the temperature range from 300 to 775 K. The Rh 'free' composition shows n-type conduction, while Rh substitution at the Co site drives the system to p-type semiconducting behavior. The lattice thermal conductivity of Zr 0.5 Hf 0.5 Co 1-x Rh x Sb 0.99 Sn 0.01 alloys rapidly decreased with increasing Rh concentration and lattice thermal conductivity as low as 3.7 W/m*K was obtained at 300 K for Zr 0.5 Hf 0.5 RhSb 0.99 Sn 0.01 . The drastic reduction of the lattice thermal conductivity is attributed to mass fluctuation induced by the Rh substitution at the Co site, as well as enhanced phonon scattering at grain boundaries due to the small grain size of the synthesized materials. - Graphical abstract: Significant reduction of the lattice thermal conductivity with increasing Rh concentration in the p-type Zr 0.5 Hf 0.5 Co 1-x Rh x Sb 0.99 Sn 0.01 half-Heusler materials prepared by solid state reaction at 1173 K.

  11. Defect studies in copper-based p-type transparent conducting oxides

    Science.gov (United States)

    Ameena, Fnu

    Among other intrinsic open-volume defects, copper vacancy (VCu) has been theoretically identified as the major acceptor in p-type Cu-based semiconducting transparent oxides, which has potential as low-cost photovoltaic absorbers in semi-transparent solar cells. A series of positron annihilation experiments with pure Cu, Cu2O, and CuO presented strong presence of VCu and its complexes in the copper oxides. The lifetime data also showed that the density of VCu was becoming higher as the oxidation state of Cu increased which was consistent with the decrease in the formation energy of VCu. Doppler broadening measurements further indicated that electrons with low momentum made more contribution to the contributed as pure Cu oxidizes to copper oxides. The metastable defects are known to be generated in Cu2O upon illumination and it has been known to affect the performance of Cu2O-based hetero-junctions used in solar cells. The metastable effect was studied using positron annihilation lifetime spectroscopy and its data showed the change in the defect population upon light exposure and the minimal effect of light-induced electron density increase in the bulk of materials to the average lifetime of the positrons. The change in the defect population is concluded to be related to the dissociation and association of VCu -- V Cu complexes. For example, the shorter lifetime under light was ascribed to the annihilation with smaller size vacancies, which explains the dissociation of the complexes with light illumination. Doppler broadening of the annihilation was independent of light illumination, which suggested that the chemical nature of the defects remained without change upon their dissociation and association -- only the size distribution of copper vacancies varied. The delafossite metal oxides, CuMIIIO2 are emerging wide-bandgap p-type semiconductors. In this research, the formation energies of structural vacancies are calculated using Van Vechten cavity model as an attempt

  12. Guided Growth of Horizontal p-Type ZnTe Nanowires

    Science.gov (United States)

    2016-01-01

    A major challenge toward large-scale integration of nanowires is the control over their alignment and position. A possible solution to this challenge is the guided growth process, which enables the synthesis of well-aligned horizontal nanowires that grow according to specific epitaxial or graphoepitaxial relations with the substrate. However, the guided growth of horizontal nanowires was demonstrated for a limited number of materials, most of which exhibit unintentional n-type behavior. Here we demonstrate the vapor–liquid–solid growth of guided horizontal ZnTe nanowires and nanowalls displaying p-type behavior on four different planes of sapphire. The growth directions of the nanowires are determined by epitaxial relations between the nanowires and the substrate or by a graphoepitaxial effect that guides their growth along nanogrooves or nanosteps along the surface. We characterized the crystallographic orientations and elemental composition of the nanowires using transmission electron microscopy and photoluminescence. The optoelectronic and electronic properties of the nanowires were studied by fabricating photodetectors and top-gate thin film transistors. These measurements showed that the guided ZnTe nanowires are p-type semiconductors and are photoconductive in the visible range. The guided growth of horizontal p-type nanowires opens up the possibility of parallel nanowire integration into functional systems with a variety of potential applications not available by other means. PMID:27885331

  13. semiconducting nanostructures: morphology and thermoelectric properties

    Science.gov (United States)

    Culebras, Mario; Torán, Raquel; Gómez, Clara M.; Cantarero, Andrés

    2014-08-01

    Semiconducting metallic oxides, especially perosvkite materials, are great candidates for thermoelectric applications due to several advantages over traditionally metallic alloys such as low production costs and high chemical stability at high temperatures. Nanostructuration can be the key to develop highly efficient thermoelectric materials. In this work, La 1- x Ca x MnO 3 perosvkite nanostructures with Ca as a dopant have been synthesized by the hydrothermal method to be used in thermoelectric applications at room temperature. Several heat treatments have been made in all samples, leading to a change in their morphology and thermoelectric properties. The best thermoelectric efficiency has been obtained for a Ca content of x=0.5. The electrical conductivity and Seebeck coefficient are strongly related to the calcium content.

  14. Degadation of semiconducting polymers by concentrated sunlight

    DEFF Research Database (Denmark)

    Tromholt, Thomas; Manceau, Matthieu; Petersen, Martin Helgesen

    2011-01-01

    infra-red spectra of MEH-PPV degraded at 1 sun intensity and at high solar concentration only showed minor deviations in degradation mechanisms. The acceleration factor was found to vary linearly with the solar concentration. Finally, a comparison of the degradation rates at 1 sun and 100 suns...... was carried out in a materials study employing five different conjugated polymers relevant to polymer solar cells for which acceleration factors in the range 19–55 were obtained.......A lens based sunlight concentration setup was used to accelerate the degradation of semiconducting polymers. Sunlight was collected outdoor and focused into an optical fiber bundle allowing for indoor experimental work. Photo-degradation of several polymers was studied by UV–vis absorbance...

  15. p-type ZnS:N nanowires: Low-temperature solvothermal doping and optoelectronic properties

    International Nuclear Information System (INIS)

    Wang, Ming-Zheng; Xie, Wei-Jie; Hu, Han; Yu, Yong-Qiang; Wu, Chun-Yan; Wang, Li; Luo, Lin-Bao

    2013-01-01

    Nitrogen doped p-type ZnS nanowires (NWs) were realized using thermal decomposition of triethylamine at a mild temperature. Field-effect transistors made from individual ZnS:N NWs revealed typical p-type conductivity behavior, with a hole mobility of 3.41 cm 2 V −1 s −1 and a hole concentration of 1.67 × 10 17  cm −3 , respectively. Further analysis found that the ZnS:N NW is sensitive to UV light irradiation with high responsivity, photoconductive gain, and good spectral selectivity. The totality of this study suggests that the solvothermal doping method is highly feasible to dope one dimensional semiconductor nanostructures for optoelectronic devices application

  16. The role of the VZn-NO-H complex in the p-type conductivity in ZnO.

    Science.gov (United States)

    Amini, M N; Saniz, R; Lamoen, D; Partoens, B

    2015-02-21

    Past research efforts aiming at obtaining stable p-type ZnO have been based on complexes involving nitrogen doping. A recent experiment by (J. G. Reynolds et al., Appl. Phys. Lett., 2013, 102, 152114) demonstrated a significant (∼10(18) cm(-3)) p-type behavior in N-doped ZnO films after appropriate annealing. The p-type conductivity was attributed to a VZn-NO-H shallow acceptor complex, formed by a Zn vacancy (VZn), N substituting O (NO), and H interstitial (Hi). We present here a first-principles hybrid functional study of this complex compared to the one without hydrogen. Our results confirm that the VZn-NO-H complex acts as an acceptor in ZnO. We find that H plays an important role, because it lowers the formation energy of the complex with respect to VZn-NO, a complex known to exhibit (unstable) p-type behavior. However, this additional H atom also occupies the hole level at the origin of the shallow behavior of VZn-NO, leaving only two states empty higher in the band gap and making the VZn-NO-H complex a deep acceptor. Therefore, we conclude that the cause of the observed p-type conductivity in experiment is not the presence of the VZn-NO-H complex, but probably the formation of the VZn-NO complex during the annealing process.

  17. Electronic structure of p type Delta doped systems

    International Nuclear Information System (INIS)

    Gaggero S, L.M.; Perez A, R.

    1998-01-01

    We summarize of the results obtained for the electronic structure of quantum wells that consist in an atomic layer doped with impurities of p type. The calculations are made within the frame worth of the wrapper function approach to independent bands and with potentials of Hartree. We study the cases reported experimentally (Be in GaAs and B in Si). We present the levels of energy, the wave functions and the rate of the electronic population between the different subbands, as well as the dependence of these magnitudes with the density of impurities in the layer. The participation of the bans of heavy holes is analysed, light and split-off band in the total electronic population. The effect of the temperature is discussed and we give a possible qualitative explanation of the experimental optical properties. (Author)

  18. Hydrogen interaction with radiation defects in p-type silicon

    CERN Document Server

    Feklisova, O V; Yakimov, E B; Weber, J

    2001-01-01

    Hydrogen interaction with radiation defects in p-type silicon has been investigated by deep-level non-stationary spectroscopy. Hydrogen is introduced into the high-energy electron-irradiated crystals under chemical etching in acid solutions at room temperature followed by the reverse-bias annealing at 380 K. It is observed that passivation of the irradiation-induced defects is accompanied by formation of novel electrically active defects with hydrogen-related profiles. Effect of hydrogen on the electrical activity of the C sub s C sub i complexes is shown for the first time. Based on the spatial distribution and passivation kinetics, possible nature of the novel complexes is analyzed. The radii for hydrogen capture by vacancies, K-centers, C sub s C sub i centers and the novel complexes are determined

  19. Effect of neutron irradiation on p-type silicon

    International Nuclear Information System (INIS)

    Sopko, B.

    1973-01-01

    The possibilities are discussed of silicon isotope reactions with neutrons of all energies. In the reactions, 30 Si is converted to a stable phosphorus isotope forming n-type impurities in silicon. The above reactions proceed as a result of thermal neutron irradiation. An experiment is reported involving irradiation of two p-type silicon single crystals having a specific resistance of 2000 ohm.cm and 5000 to 20 000 ohm.cm, respectively, which changed as a result of irradiation into n-type silicon with a given specific resistance. The specific resistance may be pre-calculated from the concentration of impurities and the time of irradiation. The effects of irradiation on other silicon parameters and thus on the suitability of silicon for the manufacture of semiconductor elements are discussed. (J.K.)

  20. Elucidating Functional Aspects of P-type ATPases

    DEFF Research Database (Denmark)

    Autzen, Henriette Elisabeth

    2015-01-01

    and helped enlighten how thapsigargin, a potent inhibitor of SERCA1a, depends on a water mediated hydrogen bond network when bound to SERCA1a. Furthermore, molecular dynamics (MD) simulations of the same P-type ATPase were used to assess a long-standing question whether cholesterol affects SERCA1a through...... similar to that of the wild type (WT) protein. The discrepancy between the newly determined crystal structure of LpCopA and the functional manifestations of the missense mutation in human CopA, could indicate that LpCopA is insufficient in structurally elucidating the effect of disease-causing mutations...... in the human CopA proteins. MD simulations, which combine coarse-grained (CG) and atomistic procedures, were set up in order to elucidate mechanistic implications exerted by the lipid bilayer on LpCopA. The MD simulations of LpCopA corroborated previous and new in vivo activity data and showed...

  1. 1/f noise in metallic and semiconducting carbon nanotubes

    Science.gov (United States)

    Reza, Shahed; Huynh, Quyen T.; Bosman, Gijs; Sippel-Oakley, Jennifer; Rinzler, Andrew G.

    2006-11-01

    The charge transport and noise properties of three terminal, gated devices containing multiple single-wall metallic and semiconducting carbon nanotubes were measured at room temperature. Applying a high voltage pulsed bias at the drain terminal the metallic tubes were ablated sequentially, enabling the separation of measured conductance and 1/f noise into metallic and semiconducting nanotube contributions. The relative low frequency excess noise of the metallic tubes was observed to be two orders of magnitude lower than that of the semiconductor tubes.

  2. Electroforming-free resistive switching memory effect in transparent p-type tin monoxide

    KAUST Repository

    Hota, M. K.

    2014-04-14

    We report reproducible low bias bipolar resistive switching behavior in p-type SnO thin film devices without extra electroforming steps. The experimental results show a stable resistance ratio of more than 100 times, switching cycling performance up to 180 cycles, and data retention of more than 103 s. The conduction mechanism varied depending on the applied voltage range and resistance state of the device. The memristive switching is shown to originate from a redox phenomenon at the Al/SnO interface, and subsequent formation/rupture of conducting filaments in the bulk of the SnO layer, likely involving oxygen vacancies and Sn interstitials.

  3. Bulk and surface event identification in p-type germanium detectors

    Science.gov (United States)

    Yang, L. T.; Li, H. B.; Wong, H. T.; Agartioglu, M.; Chen, J. H.; Jia, L. P.; Jiang, H.; Li, J.; Lin, F. K.; Lin, S. T.; Liu, S. K.; Ma, J. L.; Sevda, B.; Sharma, V.; Singh, L.; Singh, M. K.; Singh, M. K.; Soma, A. K.; Sonay, A.; Yang, S. W.; Wang, L.; Wang, Q.; Yue, Q.; Zhao, W.

    2018-04-01

    The p-type point-contact germanium detectors have been adopted for light dark matter WIMP searches and the studies of low energy neutrino physics. These detectors exhibit anomalous behavior to events located at the surface layer. The previous spectral shape method to identify these surface events from the bulk signals relies on spectral shape assumptions and the use of external calibration sources. We report an improved method in separating them by taking the ratios among different categories of in situ event samples as calibration sources. Data from CDEX-1 and TEXONO experiments are re-examined using the ratio method. Results are shown to be consistent with the spectral shape method.

  4. A statistical model of a metallic inclusion in semiconducting media

    International Nuclear Information System (INIS)

    Shikin, V. B.

    2016-01-01

    The properties of an isolated multicharged atom embedded into a semiconducting medium are discussed. The analysis generalizes the results of the known Thomas–Fermi theory for a multicharged (Z ≫ 1) atom in vacuum when it is immersed into an electron–hole gas of finite temperature. The Thomas–Fermi–Debye (TFD) atom problem is directly related to the properties of donors in low-doped semiconductors and is alternative in its conclusions to the ideal scenario of dissociation of donors. In the existing ideal statistics, an individual donor under infinitely low doping is completely ionized (a charged center does not hold its neutralizing counter-ions). A Thomas–Fermi–Debye atom (briefly, a TFD donor) remains a neutral formation that holds its screening “coat” even for infinitely low doping level, i.e., in the region of n_dλ_0"3 ≪ 1, where n_d is the concentration of the doping impurity and λ_0 is the Debye length with the parameters of intrinsic semiconductor. Various observed consequences in the behavior of a TFD donor are discussed that allow one to judge the reality of the implications of the TFD donor model.

  5. A statistical model of a metallic inclusion in semiconducting media

    Energy Technology Data Exchange (ETDEWEB)

    Shikin, V. B., E-mail: shikin@issp.ac.ru [Russian Academy of Sciences, Institute of Solid State Physics (Russian Federation)

    2016-11-15

    The properties of an isolated multicharged atom embedded into a semiconducting medium are discussed. The analysis generalizes the results of the known Thomas–Fermi theory for a multicharged (Z ≫ 1) atom in vacuum when it is immersed into an electron–hole gas of finite temperature. The Thomas–Fermi–Debye (TFD) atom problem is directly related to the properties of donors in low-doped semiconductors and is alternative in its conclusions to the ideal scenario of dissociation of donors. In the existing ideal statistics, an individual donor under infinitely low doping is completely ionized (a charged center does not hold its neutralizing counter-ions). A Thomas–Fermi–Debye atom (briefly, a TFD donor) remains a neutral formation that holds its screening “coat” even for infinitely low doping level, i.e., in the region of n{sub d}λ{sub 0}{sup 3} ≪ 1, where n{sub d} is the concentration of the doping impurity and λ{sub 0} is the Debye length with the parameters of intrinsic semiconductor. Various observed consequences in the behavior of a TFD donor are discussed that allow one to judge the reality of the implications of the TFD donor model.

  6. Majorana quasiparticles in semiconducting carbon nanotubes

    Science.gov (United States)

    Marganska, Magdalena; Milz, Lars; Izumida, Wataru; Strunk, Christoph; Grifoni, Milena

    2018-02-01

    Engineering effective p -wave superconductors hosting Majorana quasiparticles (MQPs) is nowadays of particular interest, also in view of the possible utilization of MQPs in fault-tolerant topological quantum computation. In quasi-one-dimensional systems, the parameter space for topological superconductivity is significantly reduced by the coupling between transverse modes. Together with the requirement of achieving the topological phase under experimentally feasible conditions, this strongly restricts in practice the choice of systems which can host MQPs. Here, we demonstrate that semiconducting carbon nanotubes (CNTs) in proximity with ultrathin s -wave superconductors, e.g., exfoliated NbSe2, satisfy these needs. By precise numerical tight-binding calculations in the real space, we show the emergence of localized zero-energy states at the CNT ends above a critical value of the applied magnetic field, of which we show the spatial evolution. Knowing the microscopic wave functions, we unequivocally demonstrate the Majorana nature of the localized states. An effective four-band model in the k -space, with parameters determined from the numerical spectrum, is used to calculate the topological phase diagram and its phase boundaries in analytic form. Finally, the impact of symmetry breaking contributions, like disorder and an axial component of the magnetic field, is investigated.

  7. Transparent semiconducting oxides: materials and devices

    Energy Technology Data Exchange (ETDEWEB)

    Grundmann, Marius; Frenzel, Heiko; Lajn, Alexander; Lorenz, Michael; Schein, Friedrich; von Wenckstern, Holger [Universitaet Leipzig, Institut fuer Experimentelle Physik II, Linnestr. 5, 04103 Leipzig (Germany)

    2010-06-15

    Transparent conductive oxides (TCOs) are a well-known material class allowing Ohmic conduction. A large free carrier concentration in the 10{sup 21} cm{sup -3} range and high conductivity (beyond 10{sup 4} S/cm) is feasible simultaneously with high transparency. Applications are manifold and include touch screens and front contacts for displays or solar cells. Transparent semiconducting oxides (TSO) are oxides with an intermediate free carrier concentration (typically 10{sup 14}-10{sup 18} cm{sup -3}) allowing the formation of depletion layers. We review recent results on TSO-based transistors and inverters. Most work has been reported on MISFETs. We show that MESFETs exhibit high performance and low voltage operation of oxide electronics. MESFET-based inverters offer superior performance compared to results reported for TSO MISFET-based circuits. Optical image of inverter based on thin film MESFETs with Mg{sub 0.003}Zn{sub 0.997}O channels (left) and experimental inverter characteristic for supply voltage of V{sub DD} = + 2.0 V (right). (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  8. Transport studies in p-type double quantum well samples

    International Nuclear Information System (INIS)

    Hyndman, R.J.

    2000-01-01

    The motivation for the study of double quantum well samples is that the extra spatial degree of freedom can modify the ground state energies of the system, leading to new and interesting many body effects. Electron bi-layers have been widely studied but the work presented here is the first systematic study of transport properties of a p-type, double quantum well system. The samples, grown on the 311 plane, consisted of two 100A GaAs wells separated by a 30A AlAs barrier. The thin barrier in our structures, gives rise to very strong inter-layer Coulombic interactions but in contrast to electron double quantum well samples, tunnelling between the two wells is very weak. This is due to the large effective mass of holes compared with electrons. It is possible to accurately control the total density of a sample and the relative occupancy of each well using front and back gates. A systematic study of the magnetoresistance properties of the p-type bi-layers, was carried out at low temperatures and in high magnetic fields, for samples covering a range of densities. Considerable care was required to obtain reliable results as the samples were extremely susceptible to electrical shock and were prone to drift in density slowly over time. With balanced wells, the very low tunnelling in the p-type bi-layer leads to a complete absence of all odd integers in both resistance and thermopower except for the v=1 state, ( v 1/2 in each layer) where v is the total Landau level filling factor. Unlike other FQHE features the v=1 state strengthens with increased density as inter-layer interactions increase in strength over intra-layer interactions. The state is also destroyed at a critical temperature, which is much lower than the measured activation temperature. This is taken as evidence for a finite temperature phase transition predicted for the bi-layer v=1. From the experimental observations, we construct a phase diagram for the state, which agree closely with theoretical predictions

  9. P-type diamond stripper foils for tandem ion accelerators

    International Nuclear Information System (INIS)

    Phelps, A.W.; Koba, R.

    1989-01-01

    The authors are developing a stripper foil composed of a p-type diamond membrane. This diamond stripper foil should have a significantly longer lifetime than any conventional stripper foil material. To be useful for stripper foils, the boron-doped blue diamond films must be thinner than 0.8 μm and pore-free. Two methods are compared for their ability to achieve a high nucleation areal density on a W substrate. Some W substrates were first coated with think layer of boron (≤20 nm) in order to enhance nucleation. Other W substrates were scratched with submicron diamond particles. A schematic diagram of the stripper foil is shown. Stripper foils were created by etching away the central area of W substrates. The diamond membrane was then supported by an annulus of W. Tungsten was selected as a ring-support material because of its high electrical and thermal conductivity, relatively low thermal expansion, and proven suitability as a substrate for diamond CVD. Warping or fracture of the diamond film after substrate etch-back was investigated

  10. Photoconduction spectroscopy of p-type GaSb films

    Energy Technology Data Exchange (ETDEWEB)

    Shura, M.W., E-mail: Megersa.Shura@live.nmmu.ac.za [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Wagener, V.; Botha, J.R.; Wagener, M.C. [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

    2012-05-15

    Excess carrier lifetimes (77 K) have been measured as function of the absorbed flux density in undoped p-type gallium antimonide films (GaSb/GaAs) using steady state photoconductivity measurements with the illumination wavelength of 1.1 {mu}m. Using the results from Hall effect measurements along with the relations describing the lifetimes of the excess minority carriers in the bulk of the films and at the surface, the theoretical values of the effective excess carrier lifetime in the materials were also calculated. Discrepancies between the experimental and theoretical results were described using a two-layer model, by considering the variation in the charge distribution within the layer due to the presence of surface states, as well as the band offset between the layer and the substrate. Theoretical modeling of the experimental result yields values of different parameters such as band bending at the surface, minimum value of Shockley-Read-Hall lifetime and maximum value of the surface recombination velocity.

  11. P type porous silicon resistivity and carrier transport

    International Nuclear Information System (INIS)

    Ménard, S.; Fèvre, A.; Billoué, J.; Gautier, G.

    2015-01-01

    The resistivity of p type porous silicon (PS) is reported on a wide range of PS physical properties. Al/PS/Si/Al structures were used and a rigorous experimental protocol was followed. The PS porosity (P % ) was found to be the major contributor to the PS resistivity (ρ PS ). ρ PS increases exponentially with P % . Values of ρ PS as high as 1 × 10 9 Ω cm at room temperature were obtained once P % exceeds 60%. ρ PS was found to be thermally activated, in particular, when the temperature increases from 30 to 200 °C, a decrease of three decades is observed on ρ PS . Based on these results, it was also possible to deduce the carrier transport mechanisms in PS. For P % lower than 45%, the conduction occurs through band tails and deep levels in the tissue surrounding the crystallites. When P % overpasses 45%, electrons at energy levels close to the Fermi level allow a hopping conduction from crystallite to crystallite to appear. This study confirms the potential of PS as an insulating material for applications such as power electronic devices

  12. Electronic processes in uniaxially stressed p-type germanium

    Energy Technology Data Exchange (ETDEWEB)

    Dubon, Jr., Oscar Danilo [Univ. of California, Berkeley, CA (United States)

    1996-02-01

    Effect of uniaxial stress on acceptor-related electronic processes in Ge single crystals doped with Ga, Be, and Cu were studied by Hall and photo-Hall effect measurements in conjunction with infrared spectroscopy. Stress dependence of hole lifetime in p-type Ge single crystals is used as a test for competing models of non-radiative capture of holes by acceptors. Photo-Hall effect shows that hole lifetime in Ga- and Be-doped Ge increases by over one order of magnitude with uniaxial stress at liq. He temps. Photo-Hall of Ge:Be shows a stress-induced change in the temperature dependence of hole lifetime. This is consistent with observed increase of responsivity of Ge:Ga detectors with uniaxial stress. Electronic properties of Ge:Cu are shown to change dramatically with uniaxial stress; the results provide a first explanation for the performance of uniaxially stressed, Cu-diffused Ge:Ga detectors which display a high conductivity in absence of photon signal and therefore have poor sensitivity.

  13. (Ga,Fe)Sb: A p-type ferromagnetic semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Nguyen Thanh; Anh, Le Duc; Tanaka, Masaaki [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Hai, Pham Nam [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-0033 (Japan)

    2014-09-29

    A p-type ferromagnetic semiconductor (Ga{sub 1−x},Fe{sub x})Sb (x = 3.9%–13.7%) has been grown by low-temperature molecular beam epitaxy (MBE) on GaAs(001) substrates. Reflection high energy electron diffraction patterns during the MBE growth and X-ray diffraction spectra indicate that (Ga,Fe)Sb layers have the zinc-blende crystal structure without any other crystallographic phase of precipitates. Magnetic circular dichroism (MCD) spectroscopy characterizations indicate that (Ga,Fe)Sb has the zinc-blende band structure with spin-splitting induced by s,p-d exchange interactions. The magnetic field dependence of the MCD intensity and anomalous Hall resistance of (Ga,Fe)Sb show clear hysteresis, demonstrating the presence of ferromagnetic order. The Curie temperature (T{sub C}) increases with increasing x and reaches 140 K at x = 13.7%. The crystal structure analyses, magneto-transport, and magneto-optical properties indicate that (Ga,Fe)Sb is an intrinsic ferromagnetic semiconductor.

  14. Photoconduction spectroscopy of p-type GaSb films

    International Nuclear Information System (INIS)

    Shura, M.W.; Wagener, V.; Botha, J.R.; Wagener, M.C.

    2012-01-01

    Excess carrier lifetimes (77 K) have been measured as function of the absorbed flux density in undoped p-type gallium antimonide films (GaSb/GaAs) using steady state photoconductivity measurements with the illumination wavelength of 1.1 μm. Using the results from Hall effect measurements along with the relations describing the lifetimes of the excess minority carriers in the bulk of the films and at the surface, the theoretical values of the effective excess carrier lifetime in the materials were also calculated. Discrepancies between the experimental and theoretical results were described using a two-layer model, by considering the variation in the charge distribution within the layer due to the presence of surface states, as well as the band offset between the layer and the substrate. Theoretical modeling of the experimental result yields values of different parameters such as band bending at the surface, minimum value of Shockley–Read–Hall lifetime and maximum value of the surface recombination velocity.

  15. Electronic passivation of n- and p-type GaAs using chemical vapor deposited GaS

    Science.gov (United States)

    Tabib-Azar, Massood; Kang, Soon; Macinnes, Andrew N.; Power, Michael B.; Barron, Andrew R.; Jenkins, Phillip P.; Hepp, Aloysius F.

    1993-01-01

    We report on the electronic passivation of n- and p-type GaAs using CVD cubic GaS. Au/GaS/GaAs-fabricated metal-insulator-semiconductor (MIS) structures exhibit classical high-frequency capacitor vs voltage (C-V) behavior with well-defined accumulation and inversion regions. Using high- and low-frequency C-V, the interface trap densities of about 10 exp 11/eV per sq cm on both n- and p-type GaAs are determined. The electronic condition of GaS/GaAs interface did not show any deterioration after a six week time period.

  16. Controlled oxygen vacancy induced p-type conductivity in HfO{sub 2-x} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hildebrandt, Erwin; Kurian, Jose; Mueller, Mathis M.; Kleebe, Hans-Joachim; Alff, Lambert [Institute of Materials Science, Technische Universitaet Darmstadt, 64287 Darmstadt (Germany); Schroeder, Thomas [IHP, 15236 Frankfurt/Oder (Germany)

    2011-09-12

    We have synthesized highly oxygen deficient HfO{sub 2-x} thin films by controlled oxygen engineering using reactive molecular beam epitaxy. Above a threshold value of oxygen vacancies, p-type conductivity sets in with up to 6 times 10{sup 21} charge carriers per cm{sup 3}. At the same time, the band-gap is reduced continuously by more than 1 eV. We suggest an oxygen vacancy induced p-type defect band as origin of the observed behavior.

  17. Response function of a p type - HPGe detector

    International Nuclear Information System (INIS)

    Lopez-Pino, Neivy; Cabral, Fatima Padilla; D'Alessandro, Katia; Maidana, Nora Lia; Vanin, Vito Roberto

    2011-01-01

    The response function of a HPGe detector depends on Ge crystal dimensions and dead layers thicknesses; most of them are not given by the manufacturers or change with detector damage from neutrons or contact with the atmosphere and therefore must be experimentally determined. The response function is obtained by a Monte-Carlo simulation procedure based on the Ge crystal characteristics. In this work, a p-type coaxial HPGe detector with 30% efficiency, manufactured in 1989, was investigated. The crystal radius and length and the inner hole dimensions were obtained scanning the capsule both in the radial and axial directions using 4 mm collimated beams from 137 Cs, 207 Bi point sources placed on a x-y table in steps of 2,00 mm. These dimensions were estimated comparing the experimental peak areas with those obtained by simulation using several hole configurations. In a similar procedure, the frontal dead layer thickness was determined using 2 mm collimated beams of the 59 keV gamma-rays from 241 Am and 81 keV from 133 Ba sources hitting the detector at 90 deg and 45 deg with respect to the capsule surface. The Monte Carlo detector model included, besides the crystal, hole and capsules sizes, the Ge dead-layers. The obtained spectra were folded with a gaussian resolution function to account for electronic noise. The comparison of simulated and experimental response functions for 4 mm collimated beams of 60 Co, 137 Cs, and 207 Bi points sources placed at distances of 7, 11 and 17 cm from the detector end cap showed relative deviations of about 10% in general and below 10% in the peak. The frontal dead layer thickness determined by our procedure was different from that specified by the detector manufacturer. (author)

  18. Irradiation and annealing of p-type silicon carbide

    Energy Technology Data Exchange (ETDEWEB)

    Lebedev, Alexander A.; Bogdanova, Elena V.; Grigor' eva, Maria V.; Lebedev, Sergey P. [A.F. Ioffe Physical-Technical Institute, St. Petersburg, 194021 (Russian Federation); Kozlovski, Vitaly V. [St. Petersburg State Polytechnic University, St. Petersburg, 195251 (Russian Federation)

    2014-02-21

    The development of the technology of semiconductor devices based on silicon carbide and the beginning of their industrial manufacture have made increasingly topical studies of the radiation hardness of this material on the one hand and of the proton irradiation to form high-receptivity regions on the other hand. This paper reports on a study of the carrier removal rate (V{sub d}) in p-6H-SiC under irradiation with 8 MeV protons and of the conductivity restoration in radiation- compensated epitaxial layers of various p-type silicon carbide polytypes. V{sub d} was determined by analysis of capacitance-voltage characteristics and from results of Hall effect measurements. It was found that the complete compensation of samples with the initial value of Na - Nd ≈ 1.5 × 10{sup 18} cm{sup −3} occurs at an irradiation dose of ∼1.1 × 10{sup 16} cm{sup −2}. It is shown that specific features of the sublimation layer SiC (compared to CVD layers) are clearly manifested upon the gamma and electron irradiation and are hardly noticeable under the proton and neutron irradiation. It was also found that the radiation-induced compensation of SiC is retained after its annealing at ≤1000°C. The conductivity is almost completely restored at T ≥ 1200°C. This character of annealing of the radiation compensation is independent of a silicon carbide polytype and the starting doping level of the epitaxial layer. The complete annealing temperatures considerably exceed the working temperatures of SiC-based devices. It is shown that the radiation compensation is a promising method in the technology of high-temperature devices based on SiC.

  19. Membrane Targeting of P-type ATPases in Plant Cells

    International Nuclear Information System (INIS)

    Harper, Jeffrey F.

    2004-01-01

    How membrane proteins are targeted to specific subcellular locations is a very complex and poorly understood area of research. Our long-term goal is to use P-type ATPases (ion pumps), in a model plant system Arabidopsis, as a paradigm to understand how members of a family of closely related membrane proteins can be targeted to different subcellular locations. The research is divided into two specific aims. The first aim is focused on determining the targeting destination of all 10 ACA-type calcium pumps (Arabidopsis Calcium ATPase) in Arabidopsis. ACAs represent a plant specific-subfamily of plasma membrane-type calcium pumps. In contrast to animals, the plant homologs have been found in multiple membrane systems, including the ER (ACA2), tonoplast (ACA4) and plasma membrane (ACA8). Their high degree of similarity provides a unique opportunity to use a comparative approach to delineate the membrane specific targeting information for each pump. One hypothesis to be tested is that an endomembrane located ACA can be re-directed to the plasma membrane by including targeting information from a plasma membrane isoform, ACA8. Our approach is to engineer domain swaps between pumps and monitor the targeting of chimeric proteins in plant cells using a Green Fluorescence Protein (GFP) as a tag. The second aim is to test the hypothesis that heterologous transporters can be engineered into plants and targeted to the plasma membrane by fusing them to a plasma membrane proton pump. As a test case we are evaluating the targeting properties of fusions made between a yeast sodium/proton exchanger (Sod2) and a proton pump (AHA2). This fusion may potentially lead to a new strategy for engineering salt resistant plants. Together these aims are designed to provide fundamental insights into the biogenesis and function of plant cell membrane systems

  20. n/p-Type changeable semiconductor TiO{sub 2} prepared from NTA

    Energy Technology Data Exchange (ETDEWEB)

    Li Qiuye; Wang Xiaodong; Jin Zhensheng, E-mail: zhenshengjin@henu.edu.cn; Yang Dagang; Zhang Shunli; Guo Xinyong; Yang Jianjun; Zhang Zhijun [Henan University, Key Laboratory of Special Functional Materials (China)

    2007-10-15

    A novel kind of nano-sized TiO{sub 2} (anatase) was obtained by high-temperature (400-700 deg. C) dehydration of nanotube titanic acid (H{sub 2}Ti{sub 2}O{sub 4}(OH){sub 2}, NTA). The high-temperature (400-700 deg. C) dehydrated nanotube titanic acids (HD-NTAs) with a unique defect structure exhibited a p-type semiconductor behavior under visible-light irradiation ({lambda}{>=} 420nm, E{sub photon}=2.95 eV), whereas exhibited an n-type semiconductor behavior irradiated with UV light ({lambda}{>=} 365nm, E{sub photon}=3.40 eV)

  1. Superconductivity in an Inhomogeneous Bundle of Metallic and Semiconducting Nanotubes

    Directory of Open Access Journals (Sweden)

    Ilya Grigorenko

    2013-01-01

    Full Text Available Using Bogoliubov-de Gennes formalism for inhomogeneous systems, we have studied superconducting properties of a bundle of packed carbon nanotubes, making a triangular lattice in the bundle's transverse cross-section. The bundle consists of a mixture of metallic and doped semiconducting nanotubes, which have different critical transition temperatures. We investigate how a spatially averaged superconducting order parameter and the critical transition temperature depend on the fraction of the doped semiconducting carbon nanotubes in the bundle. Our simulations suggest that the superconductivity in the bundle will be suppressed when the fraction of the doped semiconducting carbon nanotubes will be less than 0.5, which is the percolation threshold for a two-dimensional triangular lattice.

  2. Charged-particle spectroscopy in organic semiconducting single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ciavatti, A.; Basiricò, L.; Fraboni, B. [Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, 40127 Bologna (Italy); Sellin, P. J. [Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Fraleoni-Morgera, A. [ELETTRA-Sincrotrone Trieste, Strada Statale 14, Km 163.5, Basovizza, Trieste (Italy); Department of Engineering and Architecture, University of Trieste, V. Valerio 10, 34100 Trieste (Italy); CNR-Nano S3 Institute, Via Campi 213/A, 41125 Modena (Italy)

    2016-04-11

    The use of organic materials as radiation detectors has grown, due to the easy processability in liquid phase at room temperature and the possibility to cover large areas by means of low cost deposition techniques. Direct charged-particle detectors based on solution-grown Organic Semiconducting Single Crystals (OSSCs) are shown to be capable to detect charged particles in pulse mode, with very good peak discrimination. The direct charged-particle detection in OSSCs has been assessed both in the planar and in the vertical axes, and a digital pulse processing algorithm has been used to perform pulse height spectroscopy and to study the charge collection efficiency as a function of the applied bias voltage. Taking advantage of the charge spectroscopy and the good peak discrimination of pulse height spectra, an Hecht-like behavior of OSSCs radiation detectors is demonstrated. It has been possible to estimate the mobility-lifetime value in organic materials, a fundamental parameter for the characterization of radiation detectors, whose results are equal to μτ{sub coplanar} = (5 .5 ± 0.6 ) × 10{sup −6} cm{sup 2}/V and μτ{sub sandwich} = (1 .9 ± 0.2 ) × 10{sup −6} cm{sup 2}/V, values comparable to those of polycrystalline inorganic detectors. Moreover, alpha particles Time-of-Flight experiments have been carried out to estimate the drift mobility value. The results reported here indicate how charged-particle detectors based on OSSCs possess a great potential as low-cost, large area, solid-state direct detectors operating at room temperature. More interestingly, the good detection efficiency and peak discrimination observed for charged-particle detection in organic materials (hydrogen-rich molecules) are encouraging for their further exploitation in the detection of thermal and high-energy neutrons.

  3. Valence band states in Si-based p-type delta-doped field effect transistors

    International Nuclear Information System (INIS)

    Martinez-Orozco, J C; Vlaev, Stoyan J

    2009-01-01

    We present tight-binding calculations of the hole level structure of δ-doped Field Effect Transistor in a Si matrix within the first neighbors sp 3 s* semi-empirical tight-binding model including spin. We employ analytical expressions for Schottky barrier potential and the p-type δ-doped well based on a Thomas-Fermi approximation, we consider these potentials as external ones, so in the computations they are added to the diagonal terms of the tight-binding Hamiltonian, by this way we have the possibility to study the energy levels behavior as we vary the backbone parameters in the system: the two-dimensional impurity density (p 2d ) of the p-type δ-doped well and the contact voltage (V c ). The aim of this calculation is to demonstrate that the tight-binding approximation is suitable for device characterization that permits us to propose optimal values for the input parameters involved in the device design.

  4. Valence band states in Si-based p-type delta-doped field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Orozco, J C; Vlaev, Stoyan J, E-mail: jcmover@correo.unam.m [Unidad Academica de Fisica, Universidad Autonoma de Zacatecas, Calzada Solidaridad esquina con Paseo la Bufa S/N, C.P. 98060, Zacatecas, Zac. (Mexico)

    2009-05-01

    We present tight-binding calculations of the hole level structure of delta-doped Field Effect Transistor in a Si matrix within the first neighbors sp{sup 3}s* semi-empirical tight-binding model including spin. We employ analytical expressions for Schottky barrier potential and the p-type delta-doped well based on a Thomas-Fermi approximation, we consider these potentials as external ones, so in the computations they are added to the diagonal terms of the tight-binding Hamiltonian, by this way we have the possibility to study the energy levels behavior as we vary the backbone parameters in the system: the two-dimensional impurity density (p{sub 2d}) of the p-type delta-doped well and the contact voltage (V{sub c}). The aim of this calculation is to demonstrate that the tight-binding approximation is suitable for device characterization that permits us to propose optimal values for the input parameters involved in the device design.

  5. Surface chemistry of a hydrogenated mesoporous p-type silicon

    Energy Technology Data Exchange (ETDEWEB)

    Media, El-Mahdi, E-mail: belhadidz@tahoo.fr; Outemzabet, Ratiba, E-mail: oratiba@hotmail.com

    2017-02-15

    Highlights: • Due to its large specific surface porous silicon is used as substrate for drug therapy and biosensors. • We highlight the evidency of the contribution of the hydrides (SiHx) in the formation of the porous silicon. • The responsible species in the porous silicon formation are identified and quantified at different conditions. • By some chemical treatments we show that silicon surface can be turn from hydrophobic to hydrophilic. - Abstract: The finality of this work is devoted to the grafting of organic molecules on hydrogen passivated mesoporous silicon surfaces. The study would aid in the development for the formation of organic monolayers on silicon surface to be exploited for different applications such as the realisation of biosensors and medical devices. The basic material is silicon which has been first investigated by FTIR at atomistic plane during the anodic forward and backward polarization (i.e. “go” and “return”). For this study, we applied a numerical program based on least squares method to infrared absorbance spectra obtained by an in situ attenuated total reflection on p-type silicon in diluted HF electrolyte. Our numerical treatment is based on the fitting of the different bands of IR absorbance into Gaussians corresponding to the different modes of vibration of molecular groups such as siloxanes and hydrides. An adjustment of these absorbance bands is done systematically. The areas under the fitted bands permit one to follow the intensity of the different modes of vibration that exist during the anodic forward and backward polarization in order to compare the reversibility of the phenomenon of the anodic dissolution of silicon. It permits also to follow the evolution between the hydrogen silicon termination at forward and backward scanning applied potential. Finally a comparison between the states of the initial and final surface was carried out. We confirm the presence of clearly four and three distinct vibration modes

  6. Thermodynamic analysis of Mg-doped p-type GaN semiconductor

    International Nuclear Information System (INIS)

    Li Jingbo; Liang Jingkui; Rao Guanghui; Zhang Yi; Liu Guangyao; Chen Jingran; Liu Quanlin; Zhang Weijing

    2006-01-01

    A thermodynamic modeling of Mg-doped p-type GaN was carried out to describe the thermodynamic behaviors of native defects, dopants (Mg and H) and carriers in GaN. The formation energies of charged component compounds in a four-sublattice model were defined as functions of the Fermi-level based on the results of the first-principles calculations and adjusted to fit experimental data. The effect of the solubility of Mg on the low doping efficiency of Mg in GaN and the role of H in the Mg-doping MOCVD process were discussed. The modeling provides a thermodynamic approach to understand the doping process of GaN semiconductors

  7. Tough, semiconducting polyethylene-poly(3-hexylthiophene) diblock copolymers

    DEFF Research Database (Denmark)

    Müller, C.; Goffri, S.; Breiby, Dag Werner

    2007-01-01

    Semiconducting diblock copolymers of polyethylene (PE) and regioregular poly(3-hexylthiophene) (P3HT) are demonstrated to exhibit a rich phase behaviour, judicious use of which permitted us to fabricate field-effect transistors that show saturated charge carrier mobilities, mu(FET), as high as 2 x...

  8. Energy dissipation of free exciton polaritons in semiconducting films

    International Nuclear Information System (INIS)

    De Crescenzi, M.; Harbeke, G.; Tosatti, E.

    1978-08-01

    The effective (thickness-dependent) light absorption coefficient K(ω,d) is discussed for thin semiconducting films in the frequency range of free, spatially dispersive exciton polaritons. We find that (i) it oscillates strongly for small film thicknesses; (ii) it exhibits a slanted peak lineshape; (iii) its integrated strength also depends upon the exciton damping and extrapolates to zero for vanishing damping

  9. Hall-effect electric fields in semiconducting rings. II

    International Nuclear Information System (INIS)

    Gorodzha, L.V.; Emets, Yu.P.; Stril'ko, S.I.

    1987-01-01

    A calculation is presented for the current density distribution in a semiconducting ring with two electrodes symmetrically located on the outer boundary (system II, Fig. 1). The difference between this electrode position and that on the ring considered previously (system I) leads to substantial changes in the shape of the electric field

  10. Fabrication and Characterization of N-Type Zinc Oxide/P-Type Boron Doped Diamond Heterojunction

    Science.gov (United States)

    Marton, Marián; Mikolášek, Miroslav; Bruncko, Jaroslav; Novotný, Ivan; Ižák, Tibor; Vojs, Marian; Kozak, Halyna; Varga, Marián; Artemenko, Anna; Kromka, Alexander

    2015-09-01

    Diamond and ZnO are very promising wide-bandgap materials for electronic, photovoltaic and sensor applications because of their excellent electrical, optical, physical and electrochemical properties and biocompatibility. In this contribution we show that the combination of these two materials opens up the potential for fabrication of bipolar heterojunctions. Semiconducting boron doped diamond (BDD) thin films were grown on Si and UV grade silica glass substrates by HFCVD method with various boron concentration in the gas mixture. Doped zinc oxide (ZnO:Al, ZnO:Ge) thin layers were deposited by diode sputtering and pulsed lased deposition as the second semiconducting layer on the diamond films. The amount of dopants within the films was varied to obtain optimal semiconducting properties to form a bipolar p-n junction. Finally, different ZnO/BDD heterostructures were prepared and analyzed. Raman spectroscopy, SEM, Hall constant and I-V measurements were used to investigate the quality, structural and electrical properties of deposited heterostructures, respectively. I-V measurements of ZnO/BDD diodes show a rectifying ratio of 55 at ±4 V. We found that only very low dopant concentrations for both semiconducting materials enabled us to fabricate a functional p-n junction. Obtained results are promising for fabrication of optically transparent ZnO/BDD bipolar heterojunction.

  11. Impact of Nb vacancies and p-type doping of the NbCoSn-NbCoSb half-Heusler thermoelectrics.

    Science.gov (United States)

    Ferluccio, Daniella A; Smith, Ronald I; Buckman, Jim; Bos, Jan-Willem G

    2018-02-07

    The half-Heuslers NbCoSn and NbCoSb have promising thermoelectric properties. Here, an investigation of the NbCo 1+y Sn 1-z Sb z (y = 0, 0.05; 0 ≤ z ≤ 1) solid-solution is presented. In addition, the p-type doping of NbCoSn using Ti and Zr substitution is investigated. Rietveld analysis reveals the gradual creation of Nb vacancies to compensate for the n-type doping caused by the substitution of Sb in NbCoSn. This leads to a similar valence electron count (∼18.25) for the NbCo 1+y Sn 1-z Sb z samples (z > 0). Mass fluctuation disorder due to the Nb vacancies strongly decreases the lattice thermal conductivity from 10 W m -1 K -1 (z = 0) to 4.5 W m -1 K -1 (z = 0.5, 1). This is accompanied by a transition to degenerate semiconducting behaviour leading to large power factors, S 2 /ρ = 2.5-3 mW m -1 K -2 and figures of merit, ZT = 0.25-0.33 at 773 K. Ti and Zr can be used to achieve positive Seebeck values, e.g. S = +150 μV K -1 for 20% Zr at 773 K. However, the electrical resistivity, ρ 323K = 27-35 mΩ cm, remains too large for these materials to be considered useful p-type materials.

  12. On-Chip Sorting of Long Semiconducting Carbon Nanotubes for Multiple Transistors along an Identical Array.

    Science.gov (United States)

    Otsuka, Keigo; Inoue, Taiki; Maeda, Etsuo; Kometani, Reo; Chiashi, Shohei; Maruyama, Shigeo

    2017-11-28

    Ballistic transport and sub-10 nm channel lengths have been achieved in transistors containing one single-walled carbon nanotube (SWNT). To fill the gap between single-tube transistors and high-performance logic circuits for the replacement of silicon, large-area, high-density, and purely semiconducting (s-) SWNT arrays are highly desired. Here we demonstrate the fabrication of multiple transistors along a purely semiconducting SWNT array via an on-chip purification method. Water- and polymer-assisted burning from site-controlled nanogaps is developed for the reliable full-length removal of metallic SWNTs with the damage to s-SWNTs minimized even in high-density arrays. All the transistors with various channel lengths show large on-state current and excellent switching behavior in the off-state. Since our method potentially provides pure s-SWNT arrays over a large area with negligible damage, numerous transistors with arbitrary dimensions could be fabricated using a conventional semiconductor process, leading to SWNT-based logic, high-speed communication, and other next-generation electronic devices.

  13. Effect of sulfur addition on the transport properties of semiconducting iron phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    El-Desoky, M.M. [Physics Department, Faculty of Science, Suez Canal University, Suez (Egypt); Ibrahim, F.A. [Department of Physics, Faculty of Education, Suez Canal University, Al-Arish (Egypt); Hassaan, M.Y. [Department of Physics, Faculty of Science, Al-Azhar University, Nasr City, 11884 Cairo (Egypt)

    2011-08-15

    The present paper focuses on a quantitative analysis of the metallic and semiconducting behavior of electrical resistivity in La{sub 0.91}Rb{sub 0.06}Mn{sub 0.94}O{sub 3} manganites. The contribution of inherent low-frequency acoustic phonons as well as high-frequency optical phonons, to the electron-phonon resistivity is estimated following Bloch-Gruneisen model. The computed phonon resistivity is compared with that of reported metallic resistivity, accordingly {rho}diff. [{rho}exp. - {l_brace}{rho}0 + {rho}e-ph (={rho}ac + {rho}op){r_brace}] have been analysed through electron-electron scattering. Also, the difference can be varies linearly with T{sup 4.5} in accordance with the electron-magnon scattering in the double exchange process. The results reveal important aspects transport mechanism as well as point out that it is not only dominated by electron-phonon scattering, but also by electron-electron and electron-magnon scattering process. Alternatively, in high temperature regime (T {>=} T{sub P}) the semiconducting nature is discussed with Mott's variable range hopping (VRH) and small polaron conduction (SPC) model. (authors)

  14. Effect of sulfur addition on the transport properties of semiconducting iron phosphate glasses

    International Nuclear Information System (INIS)

    El-Desoky, M.M.; Ibrahim, F.A.; Hassaan, M.Y.

    2011-01-01

    The present paper focuses on a quantitative analysis of the metallic and semiconducting behavior of electrical resistivity in La 0.91 Rb 0.06 Mn 0.94 O 3 manganites. The contribution of inherent low-frequency acoustic phonons as well as high-frequency optical phonons, to the electron-phonon resistivity is estimated following Bloch-Gruneisen model. The computed phonon resistivity is compared with that of reported metallic resistivity, accordingly ρdiff. [ρexp. - {ρ0 + ρe-ph (=ρac + ρop)}] have been analysed through electron-electron scattering. Also, the difference can be varies linearly with T 4.5 in accordance with the electron-magnon scattering in the double exchange process. The results reveal important aspects transport mechanism as well as point out that it is not only dominated by electron-phonon scattering, but also by electron-electron and electron-magnon scattering process. Alternatively, in high temperature regime (T ≥ T P ) the semiconducting nature is discussed with Mott's variable range hopping (VRH) and small polaron conduction (SPC) model. (authors)

  15. In situ monitoring of stacking fault formation and its carrier lifetime mediation in p-type 4H-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Bin, E-mail: chenbinmse@gmail.com; Chen, Jun; Yao, Yuanzhao; Sekiguchi, Takashi [National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Matsuhata, Hirofumi; Okumura, Hajime [National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568 (Japan)

    2014-07-28

    Using the fine control of an electron beam (e-beam) in scanning electron microscopy with the capabilities of both electrical and optical imaging, the stacking fault (SF) formation together with its tuning of carrier lifetime was in situ monitored and investigated in p-type 4H-SiC homoepitaxial films. The SFs were formed through engineering basal plane dislocations with the energy supplied by the e-beam. The e-beam intensity required for the SF formation in the p-type films was ∼100 times higher than that in the n-type ones. The SFs reduced the minority-carrier lifetime in the p-type films, which was opposite to that observed in the n-type case. The reason for the peculiar SF behavior in the p-type 4H-SiC is discussed with the cathodoluminescence results.

  16. P-type Cu2O/SnO bilayer thin film transistors processed at low temperatures

    KAUST Repository

    Al-Jawhari, Hala A.

    2013-10-09

    P-type Cu2O/SnO bilayer thin film transistors (TFTs) with tunable performance were fabricated using room temperature sputtered copper and tin oxides. Using Cu2O film as capping layer on top of a SnO film to control its stoichiometry, we have optimized the performance of the resulting bilayer transistor. A transistor with 10 nm/15 nm Cu2O to SnO thickness ratio (25 nm total thickness) showed the best performance using a maximum process temperature of 170 C. The bilayer transistor exhibited p-type behavior with field-effect mobility, on-to-off current ratio, and threshold voltage of 0.66 cm2 V-1 s-1, 1.5×10 2, and -5.2 V, respectively. The advantages of the bilayer structure relative to single layer transistor are discussed. © 2013 American Chemical Society.

  17. Optically transparent semiconducting polymer nanonetwork for flexible and transparent electronics

    Science.gov (United States)

    Yu, Kilho; Park, Byoungwook; Kim, Geunjin; Kim, Chang-Hyun; Park, Sungjun; Kim, Jehan; Jung, Suhyun; Jeong, Soyeong; Kwon, Sooncheol; Kang, Hongkyu; Kim, Junghwan; Yoon, Myung-Han; Lee, Kwanghee

    2016-01-01

    Simultaneously achieving high optical transparency and excellent charge mobility in semiconducting polymers has presented a challenge for the application of these materials in future “flexible” and “transparent” electronics (FTEs). Here, by blending only a small amount (∼15 wt %) of a diketopyrrolopyrrole-based semiconducting polymer (DPP2T) into an inert polystyrene (PS) matrix, we introduce a polymer blend system that demonstrates both high field-effect transistor (FET) mobility and excellent optical transparency that approaches 100%. We discover that in a PS matrix, DPP2T forms a web-like, continuously connected nanonetwork that spreads throughout the thin film and provides highly efficient 2D charge pathways through extended intrachain conjugation. The remarkable physical properties achieved using our approach enable us to develop prototype high-performance FTE devices, including colorless all-polymer FET arrays and fully transparent FET-integrated polymer light-emitting diodes. PMID:27911774

  18. An alternative approach to charge transport in semiconducting electrodes

    Science.gov (United States)

    Thomchick, J.; Buoncristiani, A. M.

    1980-01-01

    The excess-carrier charge transport through the space-charge region of a semiconducting electrode is analyzed by a technique known as the flux method. In this approach reflection and transmission coefficients appropriate for a sheet of uniform semiconducting material describe its transport properties. A review is presented of the flux method showing that the results for a semiconductor electrode reduce in a limiting case to those previously found by Gaertner if the depletion layer is treated as a perfectly transmitting medium in which scattering and recombination are ignored. Then, in the framework of the flux method the depletion layer is considered more realistically by explicitly taking into account scattering and recombination processes which occur in this region.

  19. The electrical properties of semiconducting vanadium phosphate glasses

    International Nuclear Information System (INIS)

    Moridi, G.R.; Hogarth, C.A.; Hekmat Shooar, N.H.

    1984-01-01

    Vanadium phosphate glasses are a group of oxide glasses which show the semiconducting behaviour. In contrast to the conventional glasses, the conduction mechanism in these glasses is electronic, rather than being ionic. Since 1954, when the first paper appeared on the semiconducting properties of these glasses, much work has been carried out on transition-metal-oxide glasses in general, and vanadium phosphate glasses in particular. The mechanism of conduction is basicaly due to the transport of electrons between the transition-metal ions in different valency states. In the present paper, we have reviewed the previous works on the electrical characteristics of P 2 O 5 -V 2 O 5 glasses and also discussed the current theoretical ideas relevant for the interpretation of the experimental data

  20. Nonlinear wave beams in a piezo semiconducting layer

    International Nuclear Information System (INIS)

    Bagdoev, A.G.; Shekoyan, A.V.; Danoyan, Z.N.

    1997-01-01

    The propagation of quasi-monochromatic nonlinear wave in a piezo semiconducting layer taking into account electron-concentration nonlinearity is considered. For such medium the evolution equations for incoming and reflected waves are derived. Nonlinear Schroedinger equations and solutions for narrow beams are obtained. It is shown that symmetry of incoming and reflected waves does not take place. The focusing of beams is investigated.18 refs

  1. Electrical Characterization of Irradiated Semiconducting Amorphous Hydrogenated Boron Carbide

    Science.gov (United States)

    Peterson, George Glenn

    Semiconducting amorphous partially dehydrogenated boron carbide has been explored as a neutron voltaic for operation in radiation harsh environments, such as on deep space satellites/probes. A neutron voltaic device could also be used as a solid state neutron radiation detector to provide immediate alerts for radiation workers/students, as opposed to the passive dosimetry badges utilized today. Understanding how the irradiation environment effects the electrical properties of semiconducting amorphous partially dehydrogenated boron carbide is important to predicting the stability of these devices in operation. p-n heterojunction diodes were formed from the synthesis of semiconducting amorphous partially dehydrogenated boron carbide on silicon substrates through the use of plasma enhanced chemical vapor deposition (PECVD). Many forms of structural and electrical measurements and analysis have been performed on the p-n heterojunction devices as a function of both He+ ion and neutron irradiation including: transmission electron microscopy (TEM), selected area electron diffraction (SAED), current versus voltage I(V), capacitance versus voltage C(V), conductance versus frequency G(f), and charge carrier lifetime (tau). In stark contrast to nearly all other electronic devices, the electrical performance of these p-n heterojunction diodes improved with irradiation. This is most likely the result of bond defect passivation and resolution of degraded icosahedral based carborane structures (icosahedral molecules missing a B, C, or H atom(s)).

  2. Graphite based Schottky diodes formed semiconducting substrates

    Science.gov (United States)

    Schumann, Todd; Tongay, Sefaattin; Hebard, Arthur

    2010-03-01

    We demonstrate the formation of semimetal graphite/semiconductor Schottky barriers where the semiconductor is either silicon (Si), gallium arsenide (GaAs) or 4H-silicon carbide (4H-SiC). The fabrication can be as easy as allowing a dab of graphite paint to air dry on any one of the investigated semiconductors. Near room temperature, the forward-bias diode characteristics are well described by thermionic emission, and the extracted barrier heights, which are confirmed by capacitance voltage measurements, roughly follow the Schottky-Mott relation. Since the outermost layer of the graphite electrode is a single graphene sheet, we expect that graphene/semiconductor barriers will manifest similar behavior.

  3. Piezoelectric Nanogenerator Using p-Type ZnO Nanowire Arrays

    KAUST Repository

    Lu, Ming-Pei; Song, Jinhui; Lu, Ming-Yen; Chen, Min-Teng; Gao, Yifan; Chen, Lih-Juann; Wang, Zhong Lin

    2009-01-01

    Using phosphorus-doped ZnO nanowire (NW) arrays grown on silicon substrate, energy conversion using the p-type ZnO NWs has been demonstrated for the first time. The p-type ZnO NWs produce positive output voltage pulses when scanned by a conductive

  4. p-type Mesoscopic nickel oxide/organometallic perovskite heterojunction solar cells.

    Science.gov (United States)

    Wang, Kuo-Chin; Jeng, Jun-Yuan; Shen, Po-Shen; Chang, Yu-Cheng; Diau, Eric Wei-Guang; Tsai, Cheng-Hung; Chao, Tzu-Yang; Hsu, Hsu-Cheng; Lin, Pei-Ying; Chen, Peter; Guo, Tzung-Fang; Wen, Ten-Chin

    2014-04-23

    In this article, we present a new paradigm for organometallic hybrid perovskite solar cell using NiO inorganic metal oxide nanocrystalline as p-type electrode material and realized the first mesoscopic NiO/perovskite/[6,6]-phenyl C61-butyric acid methyl ester (PC61BM) heterojunction photovoltaic device. The photo-induced transient absorption spectroscopy results verified that the architecture is an effective p-type sensitized junction, which is the first inorganic p-type, metal oxide contact material for perovskite-based solar cell. Power conversion efficiency of 9.51% was achieved under AM 1.5 G illumination, which significantly surpassed the reported conventional p-type dye-sensitized solar cells. The replacement of the organic hole transport materials by a p-type metal oxide has the advantages to provide robust device architecture for further development of all-inorganic perovskite-based thin-film solar cells and tandem photovoltaics.

  5. Application of neutron transmutation doping method to initially p-type silicon material.

    Science.gov (United States)

    Kim, Myong-Seop; Kang, Ki-Doo; Park, Sang-Jun

    2009-01-01

    The neutron transmutation doping (NTD) method was applied to the initially p-type silicon in order to extend the NTD applications at HANARO. The relationship between the irradiation neutron fluence and the final resistivity of the initially p-type silicon material was investigated. The proportional constant between the neutron fluence and the resistivity was determined to be 2.3473x10(19)nOmegacm(-1). The deviation of the final resistivity from the target for almost all the irradiation results of the initially p-type silicon ingots was at a range from -5% to 2%. In addition, the burn-up effect of the boron impurities, the residual (32)P activity and the effect of the compensation characteristics for the initially p-type silicon were studied. Conclusively, the practical methodology to perform the neutron transmutation doping of the initially p-type silicon ingot was established.

  6. Properties and local environment of p-type and photoluminescent rare earths implanted into ZnO single crystals

    CERN Document Server

    Rita, EMC; Wahl, U; Soares, JC

    This thesis presents an experimental study of the local environment of p-type and Rare- Earth dopants implanted in ZnO single-crystals (SCs). Various nuclear and bulk property techniques were combined in the following evaluations: Implantation damage annealing was evaluated in ZnO SCs implanted with Fe, Sr and Ca. P-type dopants Cu and Ag implanted ZnO SCs were studied revealing that the solubility of Cu in substituting Zn is considerably higher than that of Ag. These results are discussed within the scope of the ZnO p-type doping problematic with these elements. Experimental proofs of the As “anti-site” behavior in ZnO were for the first time attained, i.e., the majority of As atoms are substitutional at the Zn site (SZn), possibly surrounded by two Zn vacancies (VZn). This reinforces the theoretical prediction that As acts as an acceptor in ZnO via the AsZn-2VZn complex formation. The co-doping of ZnO SC with In (donor) and As (acceptor) was addressed. The most striking result is the possible In-As “p...

  7. Visible luminescence in photo-electrochemically etched p-type porous silicon: Effect of illumination wavelength

    Energy Technology Data Exchange (ETDEWEB)

    Naddaf, M.; Hamadeh, H., E-mail: scientific@aec.org.sy [Department of Physics, Atomic Energy Commission of Syria (AECS), P.O. Box 6091 Damascus (Syrian Arab Republic)

    2009-08-31

    The effect of low power density of {approx} 5 {mu}W/cm{sup 2} monochromatic light of different wavelengths on the visible photoluminescence (PL) properties of photo-electrochemically formed p-type porous silicon (PS) has been investigated. Two-peak PL 'red' and 'green' is resolved in PS samples etched under blue-green wavelength illumination; 480, 533 and 580 nm. It is found that the weight of 'green' PL has maxima for the sample illuminated with 533 nm wavelength. Whereas, PL spectra of PS prepared under the influence of red illumination or in dark does not exhibit 'green' PL band, but shows considerable enhancement in the 'red' PL peak intensity. Fourier transform infrared (FTIR) spectroscopic analysis reveals the relationship between the structures of chemical bonding in PS and the observed PL behavior. In particular, the PL efficiency is highly affected by the alteration of the relative content of hydride, oxide and hydroxyl species. Moreover, relative content of hydroxyl group with respect to oxide bonding is seen to have strong relationship to the blue PL. Although, the estimated energy gap value of PS samples shows a considerable enlargement with respect to that of bulk c-Si, the FTIR, low temperature PL and Raman measurements and analysis have inconsistency with quantum confinement of PS.

  8. Visible luminescence in photo-electrochemically etched p-type porous silicon: Effect of illumination wavelength

    International Nuclear Information System (INIS)

    Naddaf, M.; Hamadeh, H.

    2010-01-01

    The effect of low power density of ∼5 μWcm - 2 monochromatic light of different wavelengths on the visible photoluminescence (PL) properties of photo-electrochemically formed p-type porous silicon (PS) has been investigated. Tow peak PL red and green is resolved in PS samples etched under blue-green wavelength illumination; 480,533 and 580 nm. It is found that the weight of green PL has maxima for the sample illuminated with 533 nm wavelength whereas, PL spectra of PS prepared under the influence of red illumination or in dark does not exhibit green PL band, but shows considerable enhancement in the red PL peak intensity. Fourier transform infrared (FTIR) spectroscopic analysis reveals the relationship between the structures of chemical bonding in PS and the observed PL behavior. In particular, the PL efficiency is highly affected by the alteration of the relative content of hydride, oxide and hydroxyl species. Moreover, relative content of hydroxyl group with respect to oxide bonding is seen to have strong relationship to the blue PL. Although, the estimated energy gap value of PS samples shows a considerable enlargement with respect to that of bulk c-Si, the FTIR, low temperature PL and Raman measurements and analysis have inconsistency with quantum confinement of PS. (author)

  9. Visible luminescence in photo-electrochemically etched p-type porous silicon: Effect of illumination wavelength

    International Nuclear Information System (INIS)

    Naddaf, M.; Hamadeh, H.

    2009-01-01

    The effect of low power density of ∼ 5 μW/cm 2 monochromatic light of different wavelengths on the visible photoluminescence (PL) properties of photo-electrochemically formed p-type porous silicon (PS) has been investigated. Two-peak PL 'red' and 'green' is resolved in PS samples etched under blue-green wavelength illumination; 480, 533 and 580 nm. It is found that the weight of 'green' PL has maxima for the sample illuminated with 533 nm wavelength. Whereas, PL spectra of PS prepared under the influence of red illumination or in dark does not exhibit 'green' PL band, but shows considerable enhancement in the 'red' PL peak intensity. Fourier transform infrared (FTIR) spectroscopic analysis reveals the relationship between the structures of chemical bonding in PS and the observed PL behavior. In particular, the PL efficiency is highly affected by the alteration of the relative content of hydride, oxide and hydroxyl species. Moreover, relative content of hydroxyl group with respect to oxide bonding is seen to have strong relationship to the blue PL. Although, the estimated energy gap value of PS samples shows a considerable enlargement with respect to that of bulk c-Si, the FTIR, low temperature PL and Raman measurements and analysis have inconsistency with quantum confinement of PS.

  10. Temperature dependence of magnetoresistance in neutron-irradiated and unirradiated high resistivity p-type silicon

    International Nuclear Information System (INIS)

    Yildirim, M.; Efeoglu, H.; Abay, B.; Yogurtcu, Y.K.

    1996-01-01

    The temperature dependence of the transverse magnetoresistance in irradiated and unirradiated p-type Si is studied in the range from 120 to 290 K. The magnetoresistance coefficients for the unirradiated left angle 001 right angle and left angle 1 anti 10 right angle samples increases with decreasing sample temperature in the range from 160 to 290 K, however, this behavior is reversed below 160 K. It is proposed that this reversal is due to the double injection effect. The magnetoresistance coefficient for the irradiated left angle 001 right angle sample increases with decreasing sample temperature in the range of 120 to 290 K and is greater than that for the unirradiated left angle 001 right angle sample. This result can be explained by increased scattering due to the increased number of defects produced by irradiation. On the other hand, the magnetoresistance coefficient for the unirradiated left angle 1 anti 10 right angle sample is found to be greater than that of the unirradiated left angle 001 right angle sample. (orig.)

  11. Itinerant magnetism in doped semiconducting β-FeSi2 and CrSi2

    Science.gov (United States)

    Singh, David J.; Parker, David

    2013-01-01

    Novel or unusual magnetism is a subject of considerable interest, particularly in metals and degenerate semiconductors. In such materials the interplay of magnetism, transport and other Fermi liquid properties can lead to fascinating physical behavior. One example is in magnetic semiconductors, where spin polarized currents may be controlled and used. We report density functional calculations predicting magnetism in doped semiconducting β-FeSi2 and CrSi2 at relatively low doping levels particularly for n-type. In this case, there is a rapid cross-over to a half-metallic state as a function of doping level. The results are discussed in relation to the electronic structure and other properties of these compounds. PMID:24343332

  12. Itinerant magnetism in doped semiconducting β-FeSi₂ and CrSi₂.

    Science.gov (United States)

    Singh, David J; Parker, David

    2013-12-17

    Novel or unusual magnetism is a subject of considerable interest, particularly in metals and degenerate semiconductors. In such materials the interplay of magnetism, transport and other Fermi liquid properties can lead to fascinating physical behavior. One example is in magnetic semiconductors, where spin polarized currents may be controlled and used. We report density functional calculations predicting magnetism in doped semiconducting β-FeSi₂ and CrSi₂ at relatively low doping levels particularly for n-type. In this case, there is a rapid cross-over to a half-metallic state as a function of doping level. The results are discussed in relation to the electronic structure and other properties of these compounds.

  13. Reassessment of the recombination parameters of chromium in n- and p-type crystalline silicon and chromium-boron pairs in p-type crystalline silicon

    International Nuclear Information System (INIS)

    Sun, Chang; Rougieux, Fiacre E.; Macdonald, Daniel

    2014-01-01

    Injection-dependent lifetime spectroscopy of both n- and p-type, Cr-doped silicon wafers with different doping levels is used to determine the defect parameters of Cr i and CrB pairs, by simultaneously fitting the measured lifetimes with the Shockley-Read-Hall model. A combined analysis of the two defects with the lifetime data measured on both n- and p-type samples enables a significant tightening of the uncertainty ranges of the parameters. The capture cross section ratios k = σ n /σ p of Cr i and CrB are determined as 3.2 (−0.6, +0) and 5.8 (−3.4, +0.6), respectively. Courtesy of a direct experimental comparison of the recombination activity of chromium in n- and p-type silicon, and as also suggested by modelling results, we conclude that chromium has a greater negative impact on carrier lifetimes in p-type silicon than n-type silicon with similar doping levels.

  14. Semiconducting Nanocrystals in Mesostructured Thin Films for Optical and Opto-Electronic Device Applications

    National Research Council Canada - National Science Library

    Chmelka, Bradley F

    2007-01-01

    ...) nanocomposite films have been measured and controlled to modify, enhance, and understand their optical and/or semiconducting properties over a hierarchy of dimensions, from molecular to macroscopic...

  15. A novel mechanism of P-type ATPase autoinhibition involving both termini of the protein

    DEFF Research Database (Denmark)

    Ekberg, Kira; Palmgren, Michael; Veierskov, Bjarke

    2010-01-01

    The activity of many P-type ATPases is found to be regulated by interacting proteins or autoinhibitory elements located in N- or C-terminal extensions. An extended C terminus of fungal and plant P-type plasma membrane H+-ATPases has long been recognized to be part of a regulatory apparatus....... This identifies the first group of P-type ATPases for which both ends of the polypeptide chain constitute regulatory domains, which together contribute to the autoinhibitory apparatus. This suggests an intricate mechanism of cis-regulation with both termini of the protein communicating to obtain the necessary...

  16. Communication: electronic band gaps of semiconducting zig-zag carbon nanotubes from many-body perturbation theory calculations.

    Science.gov (United States)

    Umari, P; Petrenko, O; Taioli, S; De Souza, M M

    2012-05-14

    Electronic band gaps for optically allowed transitions are calculated for a series of semiconducting single-walled zig-zag carbon nanotubes of increasing diameter within the many-body perturbation theory GW method. The dependence of the evaluated gaps with respect to tube diameters is then compared with those found from previous experimental data for optical gaps combined with theoretical estimations of exciton binding energies. We find that our GW gaps confirm the behavior inferred from experiment. The relationship between the electronic gap and the diameter extrapolated from the GW values is also in excellent agreement with a direct measurement recently performed through scanning tunneling spectroscopy.

  17. Scanning microwave microscopy applied to semiconducting GaAs structures

    Science.gov (United States)

    Buchter, Arne; Hoffmann, Johannes; Delvallée, Alexandra; Brinciotti, Enrico; Hapiuk, Dimitri; Licitra, Christophe; Louarn, Kevin; Arnoult, Alexandre; Almuneau, Guilhem; Piquemal, François; Zeier, Markus; Kienberger, Ferry

    2018-02-01

    A calibration algorithm based on one-port vector network analyzer (VNA) calibration for scanning microwave microscopes (SMMs) is presented and used to extract quantitative carrier densities from a semiconducting n-doped GaAs multilayer sample. This robust and versatile algorithm is instrument and frequency independent, as we demonstrate by analyzing experimental data from two different, cantilever- and tuning fork-based, microscope setups operating in a wide frequency range up to 27.5 GHz. To benchmark the SMM results, comparison with secondary ion mass spectrometry is undertaken. Furthermore, we show SMM data on a GaAs p-n junction distinguishing p- and n-doped layers.

  18. Ultraviolet optical absorptions of semiconducting copper phosphate glasses

    Science.gov (United States)

    Bae, Byeong-Soo; Weinberg, Michael C.

    1993-01-01

    Results are presented of a quantitative investigation of the change in UV optical absorption in semiconducting copper phosphate glasses with batch compositions of 40, 50, and 55 percent CuO, as a function of the Cu(2+)/Cu(total) ratio in the glasses for each glass composition. It was found that optical energy gap, E(opt), of copper phosphate glass is a function of both glass composition and Cu(2+)/Cu(total) ratio in the glass. E(opt) increases as the CuO content for fixed Cu(2+)/Cu(total) ratio and the Cu(2+)/Cu(total) ratio for fixed glass composition are reduced.

  19. Recent Advances on p-Type III-Nitride Nanowires by Molecular Beam Epitaxy

    Directory of Open Access Journals (Sweden)

    Songrui Zhao

    2017-09-01

    Full Text Available p-Type doping represents a key step towards III-nitride (InN, GaN, AlN optoelectronic devices. In the past, tremendous efforts have been devoted to obtaining high quality p-type III-nitrides, and extraordinary progress has been made in both materials and device aspects. In this article, we intend to discuss a small portion of these processes, focusing on the molecular beam epitaxy (MBE-grown p-type InN and AlN—two bottleneck material systems that limit the development of III-nitride near-infrared and deep ultraviolet (UV optoelectronic devices. We will show that by using MBE-grown nanowire structures, the long-lasting p-type doping challenges of InN and AlN can be largely addressed. New aspects of MBE growth of III-nitride nanostructures are also discussed.

  20. Origin of the p-type character of AuCl3 functionalized carbon nanotubes

    KAUST Repository

    Murat, Altynbek

    2014-02-13

    The microscopic origin of the p-type character of AuCl3 functionalized carbon nanotubes (CNTs) is investigated using first-principles self-interaction corrected density functional theory (DFT). Recent DFT calculations suggest that the p-type character of AuCl3 functionalized CNTs is due to the Cl atoms adsorbed on the CNTs. We test this hypothesis and show that adsorbed Cl atoms only lead to a p-type character for very specific concentrations and arrangements of the Cl atoms, which furthermore are not the lowest energy configurations. We therefore investigate alternative mechanisms and conclude that the p-type character is due to the adsorption of AuCl4 molecules. The unraveling of the exact nature of the p-doping adsorbates is a key step for further development of AuCl3 functionalized CNTs in water sensor applications. © 2014 American Chemical Society.

  1. Origin of the p-type character of AuCl3 functionalized carbon nanotubes

    KAUST Repository

    Murat, Altynbek; Rungger, Ivan; Jin, Chengjun; Sanvito, Stefano; Schwingenschlö gl, Udo

    2014-01-01

    The microscopic origin of the p-type character of AuCl3 functionalized carbon nanotubes (CNTs) is investigated using first-principles self-interaction corrected density functional theory (DFT). Recent DFT calculations suggest that the p

  2. A Density Functional Theory Study of Doped Tin Monoxide as a Transparent p-type Semiconductor

    KAUST Repository

    Bianchi Granato, Danilo

    2012-01-01

    that yttrium and lanthanum improves the hole mobility. Present results are in good agreement with available experimental works and help to improve the understanding on how to engineer transparent p-type materials with higher hole mobilities.

  3. High surface hole concentration p-type GaN using Mg implantation

    International Nuclear Information System (INIS)

    Long Tao; Yang Zhijian; Zhang Guoyi

    2001-01-01

    Mg ions were implanted on Mg-doped GaN grown by metalorganic chemical vapor deposition (MOCVD). The p-type GaN was achieved with high hole concentration (8.28 x 10 17 cm -3 ) conformed by Van derpauw Hall measurement after annealing at 800 degree C for 1 h. this is the first experimental report of Mg implantation on Mg-doped GaN and achieving p-type GaN with high surface hole concentration

  4. STUDY OF ELECTRICAL CHARACTERISTIC OF NEW P-TYPE TRENCHED UMOSFET

    OpenAIRE

    Akansha Ephraim*, Neelesh Agrawal, Anil Kumar, A.K. Jaiswal

    2017-01-01

    In this paper p-type trenched UMOSFET was designed without super junction and constructed like any other conventional MOSFET. Characteristic curve was studied between drain current verses drain voltage and drain current verses gate voltage. The trench was designed under TCAD simulation tool Silvaco software using etching process. The specific channel length of the p-type UMOSFET has been concentrated as 0.9 microns. The device structures are designed using Silvaco Athena and characteristics w...

  5. Method for the preparation of n-i-p type radiation detector from silicon

    International Nuclear Information System (INIS)

    Keleti, J.; Toeroek, T.; Lukacs, J.; Molnar, I.

    1978-01-01

    The patent describes a procedure for the preparation of n-i-p type silicon radiation detectors. The aim was to provide an adaquate procedure for the production of α, β, γ-detectors from silicon available on the market, either p-type single crystal silicon characterised by its boron level. The procedure and the 9 claims are illustrated by two examples. (Sz.J.)

  6. Convergence of valence bands for high thermoelectric performance for p-type InN

    International Nuclear Information System (INIS)

    Li, Hai-Zhu; Li, Ruo-Ping; Liu, Jun-Hui; Huang, Ming-Ju

    2015-01-01

    Band engineering to converge the bands to achieve high valley degeneracy is one of effective approaches for designing ideal thermoelectric materials. Convergence of many valleys in the valence band may lead to a high Seebeck coefficient, and induce promising thermoelectric performance of p-type InN. In the current work, we have systematically investigated the electronic structure and thermoelectric performance of wurtzite InN by using the density functional theory combined with semiclassical Boltzmann transport theory. Form the results, it can be found that intrinsic InN has a large Seebeck coefficient (254 μV/K) and the largest value of Z e T is 0.77. The transport properties of p-type InN are better than that of n-type one at the optimum carrier concentration, which mainly due to the large Seebeck coefficient for p-type InN, although the electrical conductivity of n-type InN is larger than that of p-type one. We found that the larger Seebeck coefficient for p-type InN may originate from the large valley degeneracy in the valence band. Moreover, the low minimum lattice thermal conductivity for InN is one key factor to become a good thermoelectric material. Therefore, p-type InN could be a potential material for further applications in the thermoelectric area.

  7. Chemical Vapor Deposition Growth of Degenerate p-Type Mo-Doped ReS2 Films and Their Homojunction.

    Science.gov (United States)

    Qin, Jing-Kai; Shao, Wen-Zhu; Xu, Cheng-Yan; Li, Yang; Ren, Dan-Dan; Song, Xiao-Guo; Zhen, Liang

    2017-05-10

    Substitutional doping of transition metal dichalcogenide two-dimensional materials has proven to be effective in tuning their intrinsic properties, such as band gap, transport characteristics, and magnetism. In this study, we realized substitutional doping of monolayer rhenium disulfide (ReS 2 ) with Mo via chemical vapor deposition. Scanning transmission electron microscopy demonstrated that Mo atoms are successfully doped into ReS 2 by substitutionally replacing Re atoms in the lattice. Electrical measurements revealed the degenerate p-type semiconductor behavior of Mo-doped ReS 2 field effect transistors, in agreement with density functional theory calculations. The p-n diode device based on a doped ReS 2 and ReS 2 homojunction exhibited gate-tunable current rectification behaviors, and the maximum rectification ratio could reach up to 150 at V d = -2/+2 V. The successful synthesis of p-type ReS 2 in this study could largely promote its application in novel electronic and optoelectronic devices.

  8. Biocompatibility of biodegradable semiconducting melanin films for nerve tissue engineering.

    Science.gov (United States)

    Bettinger, Christopher J; Bruggeman, Joost P; Misra, Asish; Borenstein, Jeffrey T; Langer, Robert

    2009-06-01

    The advancement of tissue engineering is contingent upon the development and implementation of advanced biomaterials. Conductive polymers have demonstrated potential for use as a medium for electrical stimulation, which has shown to be beneficial in many regenerative medicine strategies including neural and cardiac tissue engineering. Melanins are naturally occurring pigments that have previously been shown to exhibit unique electrical properties. This study evaluates the potential use of melanin films as a semiconducting material for tissue engineering applications. Melanin thin films were produced by solution processing and the physical properties were characterized. Films were molecularly smooth with a roughness (R(ms)) of 0.341 nm and a conductivity of 7.00+/-1.10 x 10(-5)S cm(-1) in the hydrated state. In vitro biocompatibility was evaluated by Schwann cell attachment and growth as well as neurite extension in PC12 cells. In vivo histology was evaluated by examining the biomaterial-tissue response of melanin implants placed in close proximity to peripheral nerve tissue. Melanin thin films enhanced Schwann cell growth and neurite extension compared to collagen films in vitro. Melanin films induced an inflammation response that was comparable to silicone implants in vivo. Furthermore, melanin implants were significantly resorbed after 8 weeks. These results suggest that solution-processed melanin thin films have the potential for use as a biodegradable semiconducting biomaterial for use in tissue engineering applications.

  9. High-mobility ultrathin semiconducting films prepared by spin coating.

    Science.gov (United States)

    Mitzi, David B; Kosbar, Laura L; Murray, Conal E; Copel, Matthew; Afzali, Ali

    2004-03-18

    The ability to deposit and tailor reliable semiconducting films (with a particular recent emphasis on ultrathin systems) is indispensable for contemporary solid-state electronics. The search for thin-film semiconductors that provide simultaneously high carrier mobility and convenient solution-based deposition is also an important research direction, with the resulting expectations of new technologies (such as flexible or wearable computers, large-area high-resolution displays and electronic paper) and lower-cost device fabrication. Here we demonstrate a technique for spin coating ultrathin (approximately 50 A), crystalline and continuous metal chalcogenide films, based on the low-temperature decomposition of highly soluble hydrazinium precursors. We fabricate thin-film field-effect transistors (TFTs) based on semiconducting SnS(2-x)Se(x) films, which exhibit n-type transport, large current densities (>10(5) A cm(-2)) and mobilities greater than 10 cm2 V(-1) s(-1)--an order of magnitude higher than previously reported values for spin-coated semiconductors. The spin-coating technique is expected to be applicable to a range of metal chalcogenides, particularly those based on main group metals, as well as for the fabrication of a variety of thin-film-based devices (for example, solar cells, thermoelectrics and memory devices).

  10. High-mobility ultrathin semiconducting films prepared by spin coating

    Science.gov (United States)

    Mitzi, David B.; Kosbar, Laura L.; Murray, Conal E.; Copel, Matthew; Afzali, Ali

    2004-03-01

    The ability to deposit and tailor reliable semiconducting films (with a particular recent emphasis on ultrathin systems) is indispensable for contemporary solid-state electronics. The search for thin-film semiconductors that provide simultaneously high carrier mobility and convenient solution-based deposition is also an important research direction, with the resulting expectations of new technologies (such as flexible or wearable computers, large-area high-resolution displays and electronic paper) and lower-cost device fabrication. Here we demonstrate a technique for spin coating ultrathin (~50Å), crystalline and continuous metal chalcogenide films, based on the low-temperature decomposition of highly soluble hydrazinium precursors. We fabricate thin-film field-effect transistors (TFTs) based on semiconducting SnS2-xSex films, which exhibit n-type transport, large current densities (>105Acm-2) and mobilities greater than 10cm2V-1s-1-an order of magnitude higher than previously reported values for spin-coated semiconductors. The spin-coating technique is expected to be applicable to a range of metal chalcogenides, particularly those based on main group metals, as well as for the fabrication of a variety of thin-film-based devices (for example, solar cells, thermoelectrics and memory devices).

  11. Magnetism by interfacial hybridization and p-type doping of MoS2 in Fe4N/MoS2 superlattices: A first-principles study

    KAUST Repository

    Feng, Nan

    2014-03-26

    Magnetic and electronic properties of Fe4N(111)/MoS 2(√3 × √3) superlattices are investigated by first-principles calculations, considering two models: (I) FeIFe II-S and (II) N-S interfaces, each with six stacking configurations. In model I, strong interfacial hybridization between FeI/Fe II and S results in magnetism of monolayer MoS2, with a magnetic moment of 0.33 μB for Mo located on top of Fe I. For model II, no magnetism is induced due to weak N-S interfacial bonding, and the semiconducting nature of monolayer MoS2 is preserved. Charge transfer between MoS2 and N results in p-type MoS2 with Schottky barrier heights of 0.5-0.6 eV. Our results demonstrate that the interfacial geometry and hybridization can be used to tune the magnetism and doping in Fe4N(111)/MoS2(√3 × √3) superlattices. © 2014 American Chemical Society.

  12. Magnetism by interfacial hybridization and p-type doping of MoS2 in Fe4N/MoS2 superlattices: A first-principles study

    KAUST Repository

    Feng, Nan; Mi, Wenbo; Cheng, Yingchun; Guo, Zaibing; Schwingenschlö gl, Udo; Bai, Haili

    2014-01-01

    Magnetic and electronic properties of Fe4N(111)/MoS 2(√3 × √3) superlattices are investigated by first-principles calculations, considering two models: (I) FeIFe II-S and (II) N-S interfaces, each with six stacking configurations. In model I, strong interfacial hybridization between FeI/Fe II and S results in magnetism of monolayer MoS2, with a magnetic moment of 0.33 μB for Mo located on top of Fe I. For model II, no magnetism is induced due to weak N-S interfacial bonding, and the semiconducting nature of monolayer MoS2 is preserved. Charge transfer between MoS2 and N results in p-type MoS2 with Schottky barrier heights of 0.5-0.6 eV. Our results demonstrate that the interfacial geometry and hybridization can be used to tune the magnetism and doping in Fe4N(111)/MoS2(√3 × √3) superlattices. © 2014 American Chemical Society.

  13. Electrodeposited and Sol-gel Precipitated p-type SrTi1-xFexO3-δ Semiconductors for Gas Sensing

    Directory of Open Access Journals (Sweden)

    Ralf Moos

    2007-09-01

    Full Text Available In the present contribution, three methods for the preparation of nanoscaledSrTi1-xFexO3-δ sensor films for hydrocarbon sensing were investigated. Besides screen-printed thick films based on sol-precipitated nanopowders, two novel synthesis methods,electrospinning and electrospraying, were tested successfully. All of these sensor devicesshowed improved sensor functionality in comparison to conventional microscaled thickfilms. In order to explain the impact of the enhanced surface-to-volume ratio on sensorproperties in a quantitative way, a mechanistic model was applied to micro- and nanoscaleddevices. In contrast to the conventional diffusion-reaction model that has been proposed forn-type semiconducting sensors, it contained novel approaches with respect to themicroscopic mechanism. With very few fit variables, the present model was found torepresent well sensor functionality of p-type conducting SrTi0.8Fe0.2O3-δ films. In additionto the temperature dependency of the sensor response, the effect of the specific surface areaon the sensor response was predicted.

  14. Magnetism by interfacial hybridization and p-type doping of MoS(2) in Fe(4)N/MoS(2) superlattices: a first-principles study.

    Science.gov (United States)

    Feng, Nan; Mi, Wenbo; Cheng, Yingchun; Guo, Zaibing; Schwingenschlögl, Udo; Bai, Haili

    2014-03-26

    Magnetic and electronic properties of Fe4N(111)/MoS2(√3 × √3) superlattices are investigated by first-principles calculations, considering two models: (I) Fe(I)Fe(II)-S and (II) N-S interfaces, each with six stacking configurations. In model I, strong interfacial hybridization between Fe(I)/Fe(II) and S results in magnetism of monolayer MoS2, with a magnetic moment of 0.33 μB for Mo located on top of Fe(I). For model II, no magnetism is induced due to weak N-S interfacial bonding, and the semiconducting nature of monolayer MoS2 is preserved. Charge transfer between MoS2 and N results in p-type MoS2 with Schottky barrier heights of 0.5-0.6 eV. Our results demonstrate that the interfacial geometry and hybridization can be used to tune the magnetism and doping in Fe4N(111)/MoS2(√3 × √3) superlattices.

  15. Logic circuits based on individual semiconducting and metallic carbon-nanotube devices

    International Nuclear Information System (INIS)

    Ryu, Hyeyeon; Kaelblein, Daniel; Ante, Frederik; Zschieschang, Ute; Kern, Klaus; Klauk, Hagen; Weitz, R Thomas; Schmidt, Oliver G

    2010-01-01

    Nanoscale transistors employing an individual semiconducting carbon nanotube as the channel hold great potential for logic circuits with large integration densities that can be manufactured on glass or plastic substrates. Carbon nanotubes are usually produced as a mixture of semiconducting and metallic nanotubes. Since only semiconducting nanotubes yield transistors, the metallic nanotubes are typically not utilized. However, integrated circuits often require not only transistors, but also resistive load devices. Here we show that many of the metallic carbon nanotubes that are deposited on the substrate along with the semiconducting nanotubes can be conveniently utilized as load resistors with favorable characteristics for the design of integrated circuits. We also demonstrate the fabrication of arrays of transistors and resistors, each based on an individual semiconducting or metallic carbon nanotube, and their integration on glass substrates into logic circuits with switching frequencies of up to 500 kHz using a custom-designed metal interconnect layer.

  16. 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

  17. Recent Developments in p-Type Oxide Semiconductor Materials and Devices

    KAUST Repository

    Wang, Zhenwei

    2016-02-16

    The development of transparent p-type oxide semiconductors with good performance may be a true enabler for a variety of applications where transparency, power efficiency, and greater circuit complexity are needed. Such applications include transparent electronics, displays, sensors, photovoltaics, memristors, and electrochromics. Hence, here, recent developments in materials and devices based on p-type oxide semiconductors are reviewed, including ternary Cu-bearing oxides, binary copper oxides, tin monoxide, spinel oxides, and nickel oxides. The crystal and electronic structures of these materials are discussed, along with approaches to enhance valence-band dispersion to reduce effective mass and increase mobility. Strategies to reduce interfacial defects, off-state current, and material instability are suggested. Furthermore, it is shown that promising progress has been made in the performance of various types of devices based on p-type oxides. Several innovative approaches exist to fabricate transparent complementary metal oxide semiconductor (CMOS) devices, including novel device fabrication schemes and utilization of surface chemistry effects, resulting in good inverter gains. However, despite recent developments, p-type oxides still lag in performance behind their n-type counterparts, which have entered volume production in the display market. Recent successes along with the hurdles that stand in the way of commercial success of p-type oxide semiconductors are presented.

  18. Recent Developments in p-Type Oxide Semiconductor Materials and Devices

    KAUST Repository

    Wang, Zhenwei; Nayak, Pradipta K.; Caraveo-Frescas, Jesus Alfonso; Alshareef, Husam N.

    2016-01-01

    The development of transparent p-type oxide semiconductors with good performance may be a true enabler for a variety of applications where transparency, power efficiency, and greater circuit complexity are needed. Such applications include transparent electronics, displays, sensors, photovoltaics, memristors, and electrochromics. Hence, here, recent developments in materials and devices based on p-type oxide semiconductors are reviewed, including ternary Cu-bearing oxides, binary copper oxides, tin monoxide, spinel oxides, and nickel oxides. The crystal and electronic structures of these materials are discussed, along with approaches to enhance valence-band dispersion to reduce effective mass and increase mobility. Strategies to reduce interfacial defects, off-state current, and material instability are suggested. Furthermore, it is shown that promising progress has been made in the performance of various types of devices based on p-type oxides. Several innovative approaches exist to fabricate transparent complementary metal oxide semiconductor (CMOS) devices, including novel device fabrication schemes and utilization of surface chemistry effects, resulting in good inverter gains. However, despite recent developments, p-type oxides still lag in performance behind their n-type counterparts, which have entered volume production in the display market. Recent successes along with the hurdles that stand in the way of commercial success of p-type oxide semiconductors are presented.

  19. Chemical-free n-type and p-type multilayer-graphene transistors

    Energy Technology Data Exchange (ETDEWEB)

    Dissanayake, D. M. N. M., E-mail: nandithad@voxtel-inc.com [Voxtel Inc, Lockey Laboratories, University of Oregon, Eugene Oregon 97402 (United States); Eisaman, M. D. [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Department of Electrical and Computer Engineering, Stony Brook University, Stony Brook, New York 11794 (United States); Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794 (United States)

    2016-08-01

    A single-step doping method to fabricate n- and p-type multilayer graphene (MG) top-gate field effect transistors (GFETs) is demonstrated. The transistors are fabricated on soda-lime glass substrates, with the n-type doping of MG caused by the sodium in the substrate without the addition of external chemicals. Placing a hydrogen silsesquioxane (HSQ) barrier layer between the MG and the substrate blocks the n-doping, resulting in p-type doping of the MG above regions patterned with HSQ. The HSQ is deposited in a single fabrication step using electron beam lithography, allowing the patterning of arbitrary sub-micron spatial patterns of n- and p-type doping. When a MG channel is deposited partially on the barrier and partially on the glass substrate, a p-type and n-type doping profile is created, which is used for fabricating complementary transistors pairs. Unlike chemically doped GFETs in which the external dopants are typically introduced from the top, these substrate doped GFETs allow for a top gate which gives a stronger electrostatic coupling to the channel, reducing the operating gate bias. Overall, this method enables scalable fabrication of n- and p-type complementary top-gated GFETs with high spatial resolution for graphene microelectronic applications.

  20. Nanostructured p-Type Semiconductor Electrodes and Photoelectrochemistry of Their Reduction Processes

    Directory of Open Access Journals (Sweden)

    Matteo Bonomo

    2016-05-01

    Full Text Available This review reports the properties of p-type semiconductors with nanostructured features employed as photocathodes in photoelectrochemical cells (PECs. Light absorption is crucial for the activation of the reduction processes occurring at the p-type electrode either in the pristine or in a modified/sensitized state. Beside thermodynamics, the kinetics of the electron transfer (ET process from photocathode to a redox shuttle in the oxidized form are also crucial since the flow of electrons will take place correctly if the ET rate will overcome that one of recombination and trapping events which impede the charge separation produced by the absorption of light. Depending on the nature of the chromophore, i.e., if the semiconductor itself or the chemisorbed dye-sensitizer, different energy levels will be involved in the cathodic ET process. An analysis of the general properties and requirements of electrodic materials of p-type for being efficient photoelectrocatalysts of reduction processes in dye-sensitized solar cells (DSC will be given. The working principle of p-type DSCs will be described and extended to other p-type PECs conceived and developed for the conversion of the solar radiation into chemical products of energetic/chemical interest like non fossil fuels or derivatives of carbon dioxide.

  1. Formation of p-type ZnO thin film through co-implantation

    Science.gov (United States)

    Chuang, Yao-Teng; Liou, Jhe-Wei; Woon, Wei-Yen

    2017-01-01

    We present a study on the formation of p-type ZnO thin film through ion implantation. Group V dopants (N, P) with different ionic radii are implanted into chemical vapor deposition grown ZnO thin film on GaN/sapphire substrates prior to thermal activation. It is found that mono-doped ZnO by N+ implantation results in n-type conductivity under thermal activation. Dual-doped ZnO film with a N:P ion implantation dose ratio of 4:1 is found to be p-type under certain thermal activation conditions. Higher p-type activation levels (1019 cm-3) under a wider thermal activation range are found for the N/P dual-doped ZnO film co-implanted by additional oxygen ions. From high resolution x-ray diffraction and x-ray photoelectron spectroscopy it is concluded that the observed p-type conductivities are a result of the promoted formation of PZn-4NO complex defects via the concurrent substitution of nitrogen at oxygen sites and phosphorus at zinc sites. The enhanced solubility and stability of acceptor defects in oxygen co-implanted dual-doped ZnO film are related to the reduction of oxygen vacancy defects at the surface. Our study demonstrates the prospect of the formation of stable p-type ZnO film through co-implantation.

  2. Characterization of plasma etching damage on p-type GaN using Schottky diodes

    International Nuclear Information System (INIS)

    Kato, M.; Mikamo, K.; Ichimura, M.; Kanechika, M.; Ishiguro, O.; Kachi, T.

    2008-01-01

    The plasma etching damage in p-type GaN has been characterized. From current-voltage and capacitance-voltage characteristics of Schottky diodes, it was revealed that inductively coupled plasma (ICP) etching causes an increase in series resistance of the Schottky diodes and compensation of acceptors in p-type GaN. We investigated deep levels near the valence band of p-type GaN using current deep level transient spectroscopy (DLTS), and no deep level originating from the ICP etching damage was observed. On the other hand, by capacitance DLTS measurements for n-type GaN, we observed an increase in concentration of a donor-type defect with an activation energy of 0.25 eV after the ICP etching. The origin of this defect would be due to nitrogen vacancies. We also observed this defect by photocapacitance measurements for ICP-etched p-type GaN. For both n- and p-type GaN, we found that the low bias power ICP etching is effective to reduce the concentration of this defect introduced by the high bias power ICP etching

  3. Optoelectronic properties of transparent p-type semiconductor Cu{sub x}S thin films

    Energy Technology Data Exchange (ETDEWEB)

    Parreira, P.; Valente, J. [ICEMS, IST-UTL, Lisboa (Portugal); Lavareda, G. [Departamento de Fisica, IST-UTL, Lisboa (Portugal); Nunes, F.T. [Departamento de Ciencia dos Materiais, FCT-UNL, Caparica (Portugal); Amaral, A. [Departamento de Fisica, IST-UTL, Lisboa (Portugal); ICEMS, IST-UTL, Lisboa (Portugal); Carvalho, C.N. de [Departamento de Ciencia dos Materiais, FCT-UNL, Caparica (Portugal); ICEMS, IST-UTL, Lisboa (Portugal)

    2010-07-15

    Nowadays, among the available transparent semiconductors for device use, the great majority (if not all) have n-type conductivity. The fabrication of a transparent p-type semiconductor with good optoelectronic properties (comparable to those of n-type: InO{sub x}, ITO, ZnO{sub x} or FTO) would significantly broaden the application field of thin films. However, until now no material has yet presented all the required properties. Cu{sub 2}S is a p-type narrow-band-gap material with an average optical transmittance of about 60% in the visible range for 50 nm thick films. However, due to its high conductivity at room temperature, 10 nm in thickness seems to be appropriate for device use. Cu{sub 2}S thin films with 10 nm in thickness have an optical visible transmittance of about 85% rendering them as very good candidates for transparent p-type semiconductors. In this work Cu{sub x}S thin films were deposited on alkali-free (AF) glass by thermal evaporation. The objective was not only the determination of its optoelectronic properties but also the feasibility of an active layer in a p-type thin film transistor. In our Cu{sub x}S thin films, p-type high conductivity with a total visible transmittance of about 50% have been achieved. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  4. Low temperature (< 100 °C) deposited P-type cuprous oxide thin films: Importance of controlled oxygen and deposition energy

    International Nuclear Information System (INIS)

    Li, Flora M.; Waddingham, Rob; Milne, William I.; Flewitt, Andrew J.; Speakman, Stuart; Dutson, James; Wakeham, Steve; Thwaites, Mike

    2011-01-01

    With the emergence of transparent electronics, there has been considerable advancement in n-type transparent semiconducting oxide (TSO) materials, such as ZnO, InGaZnO, and InSnO. Comparatively, the availability of p-type TSO materials is more scarce and the available materials are less mature. The development of p-type semiconductors is one of the key technologies needed to push transparent electronics and systems to the next frontier, particularly for implementing p–n junctions for solar cells and p-type transistors for complementary logic/circuits applications. Cuprous oxide (Cu 2 O) is one of the most promising candidates for p-type TSO materials. This paper reports the deposition of Cu 2 O thin films without substrate heating using a high deposition rate reactive sputtering technique, called high target utilisation sputtering (HiTUS). This technique allows independent control of the remote plasma density and the ion energy, thus providing finer control of the film properties and microstructure as well as reducing film stress. The effect of deposition parameters, including oxygen flow rate, plasma power and target power, on the properties of Cu 2 O films are reported. It is known from previously published work that the formation of pure Cu 2 O film is often difficult, due to the more ready formation or co-formation of cupric oxide (CuO). From our investigation, we established two key concurrent criteria needed for attaining Cu 2 O thin films (as opposed to CuO or mixed phase CuO/Cu 2 O films). First, the oxygen flow rate must be kept low to avoid over-oxidation of Cu 2 O to CuO and to ensure a non-oxidised/non-poisoned metallic copper target in the reactive sputtering environment. Secondly, the energy of the sputtered copper species must be kept low as higher reaction energy tends to favour the formation of CuO. The unique design of the HiTUS system enables the provision of a high density of low energy sputtered copper radicals/ions, and when combined with a

  5. Secondary ion mass spectrometry analysis of In-doped p-type GaN films

    International Nuclear Information System (INIS)

    Chiou, C.Y.; Wang, C.C.; Ling, Y.C.; Chiang, C.I.

    2003-01-01

    SIMS was used to investigate the isoelectronic In-doped p-type GaN films. The growth rate of the p-type GaN film decreased with increasing Mg and In doping. The Mg saturation in GaN was 3.55x10 19 atoms/cm 3 . The role of In as surfactant was evaluated by varying In concentrations and it was observed that the surface appeared smooth with increasing In incorporation. The Mg solubility in p-type GaN improved to 0.0025% molar ratio of the GaN with In incorporation. The In concentration results observed in neutron activation analysis (NAA) were found to be higher by a factor of 2.88 than that observed in SIMS and can be attributed to the difference in sensitivity of the two techniques. Good linearity in the results was observed from both techniques

  6. Synthesis of graft copolymers onto starch and its semiconducting properties

    Directory of Open Access Journals (Sweden)

    Nevin Çankaya

    Full Text Available Literature review has revealed that, although there are studies about grafting on natural polymers, especially on starch, few of them are about electrical properties of graft polymers. Starch methacrylate (St.met was obtained by esterification of OH groups on natural starch polymer for this purpose. Grafting of synthesized N-cyclohexyl acrylamide (NCA and commercial methyl methacrylate (MMA monomers with St.met was done by free radical polymerization method. The graft copolymers were characterized with FT-IR spectra, thermal and elemental analysis. Thermal stabilities of the graft copolymers were determined by TGA (thermo gravimetric analysis method and thermal stability of the copolymers is decreased via grafting. The electrical conductivity of the polymers was measured as a function of temperature and it has been observed that electrical conductivity increases with increasing temperature. The absorbance and transmittance versus wavelength of the polymers have been measured. Keywords: Starch, Graft copolymer, Semiconducting, Thermal stability, Starch methacrylate

  7. 14th Conference on "Microscopy of Semiconducting Materials"

    CERN Document Server

    Hutchison, J

    2005-01-01

    This is a long-established international biennial conference series, organised in conjunction with the Royal Microscopical Society, Oxford, the Institute of Physics, London and the Materials Research Society, USA. The 14th conference in the series focused on the most recent advances in the study of the structural and electronic properties of semiconducting materials by the application of transmission and scanning electron microscopy. The latest developments in the use of other important microcharacterisation techniques were also covered and included the latest work using scanning probe microscopy and also X-ray topography and diffraction. Developments in materials science and technology covering the complete range of elemental and compound semiconductors are described in this volume.

  8. Fused electron deficient semiconducting polymers for air stable electron transport

    KAUST Repository

    Onwubiko, Ada

    2018-01-23

    Conventional semiconducting polymer synthesis typically involves transition metal-mediated coupling reactions that link aromatic units with single bonds along the backbone. Rotation around these bonds contributes to conformational and energetic disorder and therefore potentially limits charge delocalisation, whereas the use of transition metals presents difficulties for sustainability and application in biological environments. Here we show that a simple aldol condensation reaction can prepare polymers where double bonds lock-in a rigid backbone conformation, thus eliminating free rotation along the conjugated backbone. This polymerisation route requires neither organometallic monomers nor transition metal catalysts and offers a reliable design strategy to facilitate delocalisation of frontier molecular orbitals, elimination of energetic disorder arising from rotational torsion and allowing closer interchain electronic coupling. These characteristics are desirable for high charge carrier mobilities. Our polymers with a high electron affinity display long wavelength NIR absorption with air stable electron transport in solution processed organic thin film transistors.

  9. Photon radiation damage simulations in CZT semiconducting detectors

    International Nuclear Information System (INIS)

    Leyva, A.; Pinnera, I.; Cruz, C.; Abreu, Y.; Dona, O.; Diaz, A.

    2009-01-01

    The use of semiconducting devices based on CZT as X and gamma rays detectors has been extended notably in the last decade thanks to their numerous advantages. The medical imagenology is one of the fields where these detectors have been successfully introduced, for example in positron emission tomography (PET). A typical CZT detector employed PET application was studied applying the Monte Carlo statistical method. All structural and geometric characteristics of the detector as well as the different photon energies usually used in the mentioned applications were considered in the simulations. Taking into account the Oen-Cahn-Holmes classical approach, the effective atomic displacement cross-sections and the number of displacements per atoms were calculated for all atom species and considered photon energies

  10. Nanoscale semiconducting silicon as a nutritional food additive

    International Nuclear Information System (INIS)

    Canham, L T

    2007-01-01

    Very high surface area silicon powders can be realized by high energy milling or electrochemical etching techniques. Such nanoscale silicon structures, whilst biodegradable in the human gastrointestinal tract, are shown to be remarkably stable in most foodstuffs and beverages. The potential for using silicon to improve the shelf life and bioavailability of specific nutrients in functional foods is highlighted. Published drug delivery data implies that the nanoentrapment of hydrophobic nutrients will significantly improve their dissolution kinetics, through a combined effect of nanostructuring and solid state modification. Nutrients loaded to date include vitamins, fish oils, lycopene and coenzyme Q10. In addition, there is growing published evidence that optimized release of orthosilicic acid, the biodegradation product of semiconducting silicon in the gut, offers beneficial effects with regard bone health. The utility of nanoscale silicon in the nutritional field shows early promise and is worthy of much further study

  11. Coexistence of negative photoconductivity and hysteresis in semiconducting graphene

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Shendong; Tang, Nujiang; Chen, Zhuo, E-mail: zchen@nju.edu.cn [School of Physics, National Laboratory of Solid State Microstructures, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, No. 22 Hankou Road, Nanjing, Jiangsu, 210093 (China); Chen, Yan; Xia, Yidong [Department of Materials Science and Engineering, National Laboratory of Solid State Microstructures, and Collaborative Innovation Center of Advanced Microstructures, No. 22 Hankou Road, Nanjing University, Nanjing, Jiangsu, 210093 (China); Xu, Xiaoyong; Hu, Jingguo, E-mail: jghu@yzu.edu.cn [School of Physics Science and Technology, Yangzhou University, No. 180 Siwangting Road, Yangzhou, Jiangsu, 225002 (China)

    2016-04-15

    Solution-processed graphene quantum dots (GQDs) possess a moderate bandgap, which make them a promising candidate for optoelectronics devices. However, negative photoconductivity (NPC) and hysteresis that happen in the photoelectric conversion process could be harmful to performance of the GQDs-based devices. So far, their origins and relations have remained elusive. Here, we investigate experimentally the origins of the NPC and hysteresis in GQDs. By comparing the hysteresis and photoconductance of GQDs under different relative humidity conditions, we are able to demonstrate that NPC and hysteresis coexist in GQDs and both are attributed to the carrier trapping effect of surface adsorbed moisture. We also demonstrate that GQDs could exhibit positive photoconductivity with three-order-of-magnitude reduction of hysteresis after a drying process and a subsequent encapsulation. Considering the pervasive moisture adsorption, our results may pave the way for a commercialization of semiconducting graphene-based and diverse solution-based optoelectronic devices.

  12. Nanoscale semiconducting silicon as a nutritional food additive

    Energy Technology Data Exchange (ETDEWEB)

    Canham, L T [pSiNutria Ltd, Malvern Hills Science Park, Geraldine Road, Malvern, Worcestershire WR14 3SZ (United Kingdom)

    2007-05-09

    Very high surface area silicon powders can be realized by high energy milling or electrochemical etching techniques. Such nanoscale silicon structures, whilst biodegradable in the human gastrointestinal tract, are shown to be remarkably stable in most foodstuffs and beverages. The potential for using silicon to improve the shelf life and bioavailability of specific nutrients in functional foods is highlighted. Published drug delivery data implies that the nanoentrapment of hydrophobic nutrients will significantly improve their dissolution kinetics, through a combined effect of nanostructuring and solid state modification. Nutrients loaded to date include vitamins, fish oils, lycopene and coenzyme Q10. In addition, there is growing published evidence that optimized release of orthosilicic acid, the biodegradation product of semiconducting silicon in the gut, offers beneficial effects with regard bone health. The utility of nanoscale silicon in the nutritional field shows early promise and is worthy of much further study.

  13. Coexistence of negative photoconductivity and hysteresis in semiconducting graphene

    International Nuclear Information System (INIS)

    Zhuang, Shendong; Tang, Nujiang; Chen, Zhuo; Chen, Yan; Xia, Yidong; Xu, Xiaoyong; Hu, Jingguo

    2016-01-01

    Solution-processed graphene quantum dots (GQDs) possess a moderate bandgap, which make them a promising candidate for optoelectronics devices. However, negative photoconductivity (NPC) and hysteresis that happen in the photoelectric conversion process could be harmful to performance of the GQDs-based devices. So far, their origins and relations have remained elusive. Here, we investigate experimentally the origins of the NPC and hysteresis in GQDs. By comparing the hysteresis and photoconductance of GQDs under different relative humidity conditions, we are able to demonstrate that NPC and hysteresis coexist in GQDs and both are attributed to the carrier trapping effect of surface adsorbed moisture. We also demonstrate that GQDs could exhibit positive photoconductivity with three-order-of-magnitude reduction of hysteresis after a drying process and a subsequent encapsulation. Considering the pervasive moisture adsorption, our results may pave the way for a commercialization of semiconducting graphene-based and diverse solution-based optoelectronic devices.

  14. Fused electron deficient semiconducting polymers for air stable electron transport

    KAUST Repository

    Onwubiko, Ada; Yue, Wan; Jellett, Cameron; Xiao, Mingfei; Chen, Hung-Yang; Ravva, Mahesh Kumar; Hanifi, David A.; Knall, Astrid-Caroline; Purushothaman, Balaji; Nikolka, Mark; Flores, Jean-Charles; Salleo, Alberto; Bredas, Jean-Luc; Sirringhaus, Henning; Hayoz, Pascal; McCulloch, Iain

    2018-01-01

    Conventional semiconducting polymer synthesis typically involves transition metal-mediated coupling reactions that link aromatic units with single bonds along the backbone. Rotation around these bonds contributes to conformational and energetic disorder and therefore potentially limits charge delocalisation, whereas the use of transition metals presents difficulties for sustainability and application in biological environments. Here we show that a simple aldol condensation reaction can prepare polymers where double bonds lock-in a rigid backbone conformation, thus eliminating free rotation along the conjugated backbone. This polymerisation route requires neither organometallic monomers nor transition metal catalysts and offers a reliable design strategy to facilitate delocalisation of frontier molecular orbitals, elimination of energetic disorder arising from rotational torsion and allowing closer interchain electronic coupling. These characteristics are desirable for high charge carrier mobilities. Our polymers with a high electron affinity display long wavelength NIR absorption with air stable electron transport in solution processed organic thin film transistors.

  15. Fused electron deficient semiconducting polymers for air stable electron transport.

    Science.gov (United States)

    Onwubiko, Ada; Yue, Wan; Jellett, Cameron; Xiao, Mingfei; Chen, Hung-Yang; Ravva, Mahesh Kumar; Hanifi, David A; Knall, Astrid-Caroline; Purushothaman, Balaji; Nikolka, Mark; Flores, Jean-Charles; Salleo, Alberto; Bredas, Jean-Luc; Sirringhaus, Henning; Hayoz, Pascal; McCulloch, Iain

    2018-01-29

    Conventional semiconducting polymer synthesis typically involves transition metal-mediated coupling reactions that link aromatic units with single bonds along the backbone. Rotation around these bonds contributes to conformational and energetic disorder and therefore potentially limits charge delocalisation, whereas the use of transition metals presents difficulties for sustainability and application in biological environments. Here we show that a simple aldol condensation reaction can prepare polymers where double bonds lock-in a rigid backbone conformation, thus eliminating free rotation along the conjugated backbone. This polymerisation route requires neither organometallic monomers nor transition metal catalysts and offers a reliable design strategy to facilitate delocalisation of frontier molecular orbitals, elimination of energetic disorder arising from rotational torsion and allowing closer interchain electronic coupling. These characteristics are desirable for high charge carrier mobilities. Our polymers with a high electron affinity display long wavelength NIR absorption with air stable electron transport in solution processed organic thin film transistors.

  16. A simple model to estimate the optimal doping of p - Type oxide superconductors

    Directory of Open Access Journals (Sweden)

    Adir Moysés Luiz

    2008-12-01

    Full Text Available Oxygen doping of superconductors is discussed. Doping high-Tc superconductors with oxygen seems to be more efficient than other doping procedures. Using the assumption of double valence fluctuations, we present a simple model to estimate the optimal doping of p-type oxide superconductors. The experimental values of oxygen content for optimal doping of the most important p-type oxide superconductors can be accounted for adequately using this simple model. We expect that our simple model will encourage further experimental and theoretical researches in superconducting materials.

  17. Hall and thermoelectric evaluation of p-type InAs

    Energy Technology Data Exchange (ETDEWEB)

    Wagener, M.C., E-mail: magnus.wagener@nmmu.ac.z [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Wagener, V.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)

    2009-12-15

    This paper compares the galvanometric and thermoelectric evaluation of the electrical characteristics of narrow gap semiconductors. In particular, the influence of a surface inversion layer is incorporated into the analysis of the temperature-dependent Hall and thermoelectric measurements of p-type InAs. The temperature at which the Seebeck coefficient of p-type material changes sign is shown to be unaffected by the presence of degenerate conduction paths. This finding consequently facilitated the direct determination of the acceptor density of lightly doped thin film InAs.

  18. In and out of the cation pumps: P-type ATPase structure revisited

    DEFF Research Database (Denmark)

    Bublitz, Maike; Poulsen, Hanne; Morth, Jens Preben

    2010-01-01

    Active transport across membranes is a crucial requirement for life. P-type ATPases build up electrochemical gradients at the expense of ATP by forming and splitting a covalent phosphoenzyme intermediate, coupled to conformational changes in the transmembrane section where the ions are translocated....... The marked increment during the last three years in the number of crystal structures of P-type ATPases has greatly improved our understanding of the similarities and differences of pumps with different ion specificities, since the structures of the Ca2+-ATPase, the Na+,K+-ATPase and the H+-ATPase can now...

  19. High surface hole concentration p-type GaN using Mg implantation

    CERN Document Server

    Long Tao; Zhang Guo Yi

    2001-01-01

    Mg ions were implanted on Mg-doped GaN grown by metalorganic chemical vapor deposition (MOCVD). The p-type GaN was achieved with high hole concentration (8.28 x 10 sup 1 sup 7 cm sup - sup 3) conformed by Van derpauw Hall measurement after annealing at 800 degree C for 1 h. this is the first experimental report of Mg implantation on Mg-doped GaN and achieving p-type GaN with high surface hole concentration

  20. Optical properties of Mg doped p-type GaN nanowires

    Science.gov (United States)

    Patsha, Avinash; Pandian, Ramanathaswamy; Dhara, S.; Tyagi, A. K.

    2015-06-01

    Mg doped p-type GaN nanowires are grown using chemical vapor deposition technique in vapor-liquid-solid (VLS) process. Morphological and structural studies confirm the VLS growth process of nanowires and wurtzite phase of GaN. We report the optical properties of Mg doped p-type GaN nanowires. Low temperature photoluminescence studies on as-grown and post-growth annealed samples reveal the successful incorporation of Mg dopants. The as-grwon and annealed samples show passivation and activation of Mg dopants, respectively, in GaN nanowires.

  1. Dual ohmic contact to N- and P-type silicon carbide

    Science.gov (United States)

    Okojie, Robert S. (Inventor)

    2013-01-01

    Simultaneous formation of electrical ohmic contacts to silicon carbide (SiC) semiconductor having donor and acceptor impurities (n- and p-type doping, respectively) is disclosed. The innovation provides for ohmic contacts formed on SiC layers having n- and p-doping at one process step during the fabrication of the semiconductor device. Further, the innovation provides a non-discriminatory, universal ohmic contact to both n- and p-type SiC, enhancing reliability of the specific contact resistivity when operated at temperatures in excess of 600.degree. C.

  2. On the feasibility of p-type Ga2O3

    Science.gov (United States)

    Kyrtsos, Alexandros; Matsubara, Masahiko; Bellotti, Enrico

    2018-01-01

    We investigate the various cation substitutional dopants in Ga2O3 for the possibility of p-type conductivity using density functional theory. Our calculations include both standard density functional theory and hybrid functional calculations. We demonstrate that all the investigated dopants result in deep acceptor levels, not able to contribute to the p-type conductivity of Ga2O3. In light of these results, we compare our findings with other wide bandgap oxides and reexamine previous experiments on zinc doping in Ga2O3.

  3. Subband structure comparison between n- and p- type double delta-doped Ga As quantum wells

    International Nuclear Information System (INIS)

    Rodriguez V, I.; Gaggero S, L.M.

    2004-01-01

    We compute the electron level structure (n-type) and the hole subband structure (p-type) of double -doped GaAs (DDD) quantum wells, considering exchange effects. The Thomas-Fermi (TF), and Thomas-Fermi-Dirac (TFD) approximations have been applied in order to describe the bending of the conduction and valence band, respectively. The electron and the hole subband structure study indicates that exchange effects are more important in p-type DDD quantum wells than in n-type DDD Also our results agree with the experimental data available. (Author) 33 refs., 2 tabs., 5 figs

  4. Hall and thermoelectric evaluation of p-type InAs

    International Nuclear Information System (INIS)

    Wagener, M.C.; Wagener, V.; Botha, J.R.

    2009-01-01

    This paper compares the galvanometric and thermoelectric evaluation of the electrical characteristics of narrow gap semiconductors. In particular, the influence of a surface inversion layer is incorporated into the analysis of the temperature-dependent Hall and thermoelectric measurements of p-type InAs. The temperature at which the Seebeck coefficient of p-type material changes sign is shown to be unaffected by the presence of degenerate conduction paths. This finding consequently facilitated the direct determination of the acceptor density of lightly doped thin film InAs.

  5. Pyrochlore type semiconducting ceramic oxides in Ca-Ce-Ti-M-O system (M = Nb or Ta)-Structure, microstructure and electrical properties

    International Nuclear Information System (INIS)

    Deepa, M.; Prabhakar Rao, P.; Radhakrishnan, A.N.; Sibi, K.S.; Koshy, Peter

    2009-01-01

    A new series of pyrochlore type ceramic semiconducting oxides in Ca-Ce-Ti-M-O (M = Nb or Ta) system has been synthesized by the conventional ceramic route. The electrical conductivity measurements show that these oxides exhibit semiconducting behavior and the conductivity increases with the Ce content in the compound. Activation energy of the current carriers is in the range of 0.5-1.6 eV. The electrical conductivity in these oxides is due to the presence of Ce 3+ , which remains in the reduced state without being oxidized to Ce 4+ by structural stabilization. The photoluminescence and X-ray photoelectron spectroscopy analysis corroborate the presence of Ce in the 3+ state. Impedance spectral analysis is carried out to evaluate the transport properties and indicates that the conduction in these compounds is mainly due to electronic contribution. The X-ray powder diffraction and Raman spectroscopy analysis establishes that these oxides belong to a cubic pyrochlore type structure.

  6. Demethoxycurcumin is a potent inhibitor of P-type ATPases from diverse kingdoms of life

    DEFF Research Database (Denmark)

    Dao, Trong Tuan; Sehgal, Pankaj; Thanh Tung, Truong

    2016-01-01

    the curcuminoids, demethoxycurcumin was the most potent inhibitor of all tested P-type ATPases from fungal (Pma1p; H+-ATPase), plant (AHA2; H+-ATPase) and animal (SERCA; Ca2+-ATPase) cells. All three curcuminoids acted as non-competitive antagonist to ATP and hence may bind to a highly conserved allosteric site...

  7. Room temperature deposition of amorphous p-type CuFeO2 and ...

    Indian Academy of Sciences (India)

    fabrication of CuFeO2/n-Si heterojunction by RF sputtering method. TAO ZHU1 ... Transparent conducting amorphous p-type CuFeO2 (CFO) thin film was prepared by radio-frequency ... Delafossite oxides CuMO2 (M is trivalent cation, such as.

  8. Room temperature deposition of amorphous p-type CuFeO2 and ...

    Indian Academy of Sciences (India)

    2Key Lab of Novel Thin Film Solar Cells, Chinese Academy of Sciences, Hefei 230031, China. 3University of Science and Technology of China, Hefei 230026, China. MS received 14 October 2015; accepted 28 December 2015. Abstract. Transparent conducting amorphous p-type CuFeO2 (CFO) thin film was prepared by ...

  9. Tetrahydrocarbazoles are a novel class of potent P-type ATPase inhibitors with antifungal activity

    DEFF Research Database (Denmark)

    Bublitz, Maike; Kjellerup, Lasse; Cohrt, Karen O.Hanlon

    2018-01-01

    We have identified a series of tetrahydrocarbazoles as novel P-type ATPase inhibitors. Using a set of rationally designed analogues, we have analyzed their structure-activity relationship using functional assays, crystallographic data and computational modeling. We found that tetrahydrocarbazoles...

  10. Ge-intercalated graphene: The origin of the p-type to n-type transition

    KAUST Repository

    Kaloni, Thaneshwor P.; Kahaly, M. Upadhyay; Cheng, Yingchun; Schwingenschlö gl, Udo

    2012-01-01

    deposition on the surface; and iii) cluster intercalation. All other configurations under study result in p-type states irrespective of the Ge coverage. We explain the origin of the different doping states and establish the conditions under which a transition

  11. Nanoscale Cross-Point Resistive Switching Memory Comprising p-Type SnO Bilayers

    KAUST Repository

    Hota, Mrinal Kanti; Hedhili, Mohamed N.; Wang, Qingxiao; Melnikov, Vasily; Mohammed, Omar F.; Alshareef, Husam N.

    2015-01-01

    Reproducible low-voltage bipolar resistive switching is reported in bilayer structures of p-type SnO films. Specifically, a bilayer homojunction comprising SnOx (oxygen-rich) and SnOy (oxygen-deficient) in nanoscale cross-point (300 × 300 nm2

  12. Characterization of 3D-DDTC detectors on p-type substrates

    CERN Document Server

    Betta, G -F Dalla; Bosisio, Luciano; Darbo, Giovanni; Gabos, Paolo; Gemme, Claudia; Koehler, Michael; La Rosa, Alessandro; Parzefall, Ulrich; Pernegger, Heinz; Piemonte, Claudio; Povoli, Marco; Rachevskaia, Irina; Ronchin, Sabina; Wiik, Liv; Zoboli, Aanrea; Zorzi, Nicola

    2009-01-01

    We report on the electrical and functional characterization of 3D Double-side, Double-Type-Column (3D- DDTC) detectors fabricated on p-type substrates. Results relevant to detectors in the diode, strip and pixel configurations are presented, and demonstrate a clear improvement in the charge collection performance compared to the first prototypes of these detectors.

  13. P-type silicon surface barrier detector used for x-ray dosimetry

    International Nuclear Information System (INIS)

    Yamamoto, Hisao; Hatakeyama, Satoru; Norimura, Toshiyuki; Tsuchiya, Takehiko

    1983-01-01

    Responses to X-rays of a P-type surface barrier detector fabricated in our laboratory were studied, taking into consideration the dependence on the temperature in order to examine its applicability to dosimetry of short-range radiation. The study was also made in the case of N-type surface barrier detector. At room temperature, the short-circuit current increased linearly with exposure dose rate (15 - 50 R/min) for N- and P-type detectors. The open-circuit voltage showed a nonlinear dependence. With increasing temperature, the short-circuit current for the N-type detector was approximately constant up to 30 0 C and then decreased, though the open-circuit voltage decreased linearly. For the P- type detector, both open-circuit voltage and short-circuit current decreased almost linearly with increasing temperature. While a P-type detector is still open to some improvements, these results indicate that it can be used as a dosimeter. (author)

  14. Structure and mechanism of Zn2+-transporting P-type ATPases

    DEFF Research Database (Denmark)

    Wang, Kaituo; Sitsel, Oleg; Meloni, Gabriele

    2014-01-01

    Zinc is an essential micronutrient for all living organisms. It is required for signalling and proper functioning of a range of proteins involved in, for example, DNA binding and enzymatic catalysis1. In prokaryotes and photosynthetic eukaryotes, Zn2+-transporting P-type ATPases of class IB (Znt...

  15. Electrical Properties Of Amorphous Selenium (aSe)/p-Type Silicon ...

    African Journals Online (AJOL)

    aSe) on four chemically etched p-type silicon crystals (pSi) each of 5Ω-cm resistivity and carrier concentration of 2.8x1015cm-3. Two of the pSi crystals have surface orientation of (111) while the other two crystals have (100) surface orientation.

  16. Rectification properties of n-type nanocrystalline diamond heterojunctions to p-type silicon carbide at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Goto, Masaki; Amano, Ryo; Shimoda, Naotaka [Graduate School of Automotive Science, Kyushu University, Nishiku, Fukuoka 819-0395 (Japan); Kato, Yoshimine, E-mail: yoshimine.kato@zaiko.kyushu-u.ac.jp [Department of Materials Science and Engineering, Kyushu University, Nishiku, Fukuoka 819-0395 (Japan); Teii, Kungen [Department of Applied Science for Electronics and Materials, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan)

    2014-04-14

    Highly rectifying heterojunctions of n-type nanocrystalline diamond (NCD) films to p-type 4H-SiC substrates are fabricated to develop p-n junction diodes operable at high temperatures. In reverse bias condition, a potential barrier for holes at the interface prevents the injection of reverse leakage current from the NCD into the SiC and achieves the high rectification ratios of the order of 10{sup 7} at room temperature and 10{sup 4} even at 570 K. The mechanism of the forward current injection is described with the upward shift of the defect energy levels in the NCD to the conduction band of the SiC by forward biasing. The forward current shows different behavior from typical SiC Schottky diodes at high temperatures.

  17. Thermoelectric properties of fine-grained FeVSb half-Heusler alloys tuned to p-type by substituting vanadium with titanium

    International Nuclear Information System (INIS)

    Zou, Minmin; Li, Jing-Feng; Kita, Takuji

    2013-01-01

    Fine-grained Ti-doped FeVSb half-Heusler alloys were synthesized by combining mechanical alloying and spark plasma sintering and their thermoelectric properties were investigated with an emphasis on the influences of Ti doping and phase purity. It was found that substituting V with Ti can change the electrical transport behavior from n-type to p-type due to one less valence electron of Ti than V, and the sample with nominal composition FeV 0.8 Ti 0.4 Sb exhibits the largest Seebeck coefficient and the maximum power factor. By optimizing the sintering temperature and applying annealing treatment, the power factor is significantly improved and the thermal conductivity is reduced simultaneously, resulting in a ZT value of 0.43 at 500 °C, which is relatively high as for p-type half-Heusler alloys containing earth-abundant elements. - Graphical abstract: Fine-grained Ti-doped FeVSb alloys were prepared by the MA-SPS method. The maximum ZT value reaches 0.43 at 500 °C, which is relatively high for p-type half-Heusler alloys. Highlights: ► Ti-doped FeVSb half-Heusler alloys were synthesized by combining MA and SPS. ► Substituting V with Ti changes the electrical behavior from n-type to p-type. ► Thermoelectric properties are improved by optimizing sintering temperature. ► Thermoelectric properties are further improved by applying annealing treatment. ► A high ZT value of 0.43 is obtained at 500 °C for p-type Ti-doped FeVSb alloys.

  18. Effects of interface modification by H2O2 treatment on the electrical properties of n-type ZnO/p-type Si diodes

    International Nuclear Information System (INIS)

    He, Guan-Ru; Lin, Yow-Jon; Chang, Hsing-Cheng; Chen, Ya-Hui

    2012-01-01

    The fabrication and detailed electrical properties of heterojunction diodes based on n-type ZnO and p-type Si were reported. The effect of interface modification by H 2 O 2 treatment on the electrical properties of n-type ZnO/p-type Si diodes was investigated. The n-type ZnO/p-type Si diode without H 2 O 2 treatment showed a poor rectifying behavior with an ideality factor (n) of 2.5 and high leakage, indicating that the interfacial ZnSi x O y layer influenced the electronic conduction through the device. However, the n-type ZnO/p-type Si diode with H 2 O 2 treatment showed a good rectifying behavior with n of 1.3 and low leakage. This is because the thin SiO x layer acts as a thermodynamically stable buffer layer to suppress interfacial reaction between ZnO and Si. In addition, the enhanced photo-responsivity can be interpreted by the device rectifying performance and interface passivation. - Highlights: ► The electrical properties of n-ZnO/p-Si heterojunction diodes were researched. ► The n-ZnO/p-Si diode without H 2 O 2 treatment showed a poor rectifying behavior. ► The n-ZnO/H 2 O 2 -treated p-Si diode showed a good rectifying behavior. ► The enhanced responsivity can be interpreted by the device rectifying performance.

  19. Organic small molecule semiconducting chromophores for use in organic electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Welch, Gregory C.; Hoven, Corey V.; Nguyen, Thuc-Quyen

    2018-02-13

    Small organic molecule semi-conducting chromophores containing a pyridalthiadiazole, pyridaloxadiazole, or pyridaltriazole core structure are disclosed. Such compounds can be used in organic heterojunction devices, such as organic small molecule solar cells and transistors.

  20. Surface photovoltage studies of p-type AlGaN layers after reactive-ion etching

    Science.gov (United States)

    McNamara, J. D.; Phumisithikul, K. L.; Baski, A. A.; Marini, J.; Shahedipour-Sandvik, F.; Das, S.; Reshchikov, M. A.

    2016-10-01

    The surface photovoltage (SPV) technique was used to study the surface and electrical properties of Mg-doped, p-type AlxGa1-xN (0.06 GaN:Mg thin films and from the predictions of a thermionic model for the SPV behavior. In particular, the SPV of the p-AlGaN:Mg layers exhibited slower-than-expected transients under ultraviolet illumination and delayed restoration to the initial dark value. The slow transients and delayed restorations can be attributed to a defective surface region which interferes with normal thermionic processes. The top 45 nm of the p-AlGaN:Mg layer was etched using a reactive-ion etch which caused the SPV behavior to be substantially different. From this study, it can be concluded that a defective, near-surface region is inhibiting the change in positive surface charge by allowing tunneling or hopping conductivity of holes from the bulk to the surface, or by the trapping of electrons traveling to the surface by a high concentration of defects in the near-surface region. Etching removes the defective layer and reveals a region of presumably higher quality, as evidenced by substantial changes in the SPV behavior.

  1. Structural Distortion Stabilizing the Antiferromagnetic and Semiconducting Ground State of BaMn2As2

    Directory of Open Access Journals (Sweden)

    Ekkehard Krüger

    2016-09-01

    Full Text Available We report evidence that the experimentally found antiferromagnetic structure as well as the semiconducting ground state of BaMn 2 As 2 are caused by optimally-localized Wannier states of special symmetry existing at the Fermi level of BaMn 2 As 2 . In addition, we find that a (small tetragonal distortion of the crystal is required to stabilize the antiferromagnetic semiconducting state. To our knowledge, this distortion has not yet been established experimentally.

  2. Efficiency Improvement of HIT Solar Cells on p-Type Si Wafers.

    Science.gov (United States)

    Wei, Chun-You; Lin, Chu-Hsuan; Hsiao, Hao-Tse; Yang, Po-Chuan; Wang, Chih-Ming; Pan, Yen-Chih

    2013-11-22

    Single crystal silicon solar cells are still predominant in the market due to the abundance of silicon on earth and their acceptable efficiency. Different solar-cell structures of single crystalline Si have been investigated to boost efficiency; the heterojunction with intrinsic thin layer (HIT) structure is currently the leading technology. The record efficiency values of state-of-the art HIT solar cells have always been based on n-type single-crystalline Si wafers. Improving the efficiency of cells based on p-type single-crystalline Si wafers could provide broader options for the development of HIT solar cells. In this study, we varied the thickness of intrinsic hydrogenated amorphous Si layer to improve the efficiency of HIT solar cells on p-type Si wafers.

  3. P-type Al-doped Cr-deficient CrN thin films for thermoelectrics

    Science.gov (United States)

    le Febvrier, Arnaud; Van Nong, Ngo; Abadias, Gregory; Eklund, Per

    2018-05-01

    Thermoelectric properties of chromium nitride (CrN)-based films grown on c-plane sapphire by dc reactive magnetron sputtering were investigated. In this work, aluminum doping was introduced in CrN (degenerate n-type semiconductor) by co-deposition. Under the present deposition conditions, over-stoichiometry in nitrogen (CrN1+δ) rock-salt structure is obtained. A p-type conduction is observed with nitrogen-rich CrN combined with aluminum doping. The Cr0.96Al0.04N1.17 film exhibited a high Seebeck coefficient and a sufficient power factor at 300 °C. These results are a starting point for designing p-type/n-type thermoelectric materials based on chromium nitride films, which are cheap and routinely grown on the industrial scale.

  4. In and out of the cation pumps: P-type ATPase structure revisited

    DEFF Research Database (Denmark)

    Bublitz, Maike; Poulsen, Hanne; Morth, Jens Preben

    2010-01-01

    . The marked increment during the last three years in the number of crystal structures of P-type ATPases has greatly improved our understanding of the similarities and differences of pumps with different ion specificities, since the structures of the Ca2+-ATPase, the Na+,K+-ATPase and the H+-ATPase can now......Active transport across membranes is a crucial requirement for life. P-type ATPases build up electrochemical gradients at the expense of ATP by forming and splitting a covalent phosphoenzyme intermediate, coupled to conformational changes in the transmembrane section where the ions are translocated...... be compared directly. Mechanisms for ion gating, charge neutralization and backflow prevention are starting to emerge from comparative structural analysis; and in combination with functional studies of mutated pumps this provides a framework for speculating on how the ions are bound and released as well...

  5. Enhancement of p-type mobility in tin monoxide by native defects

    KAUST Repository

    Granato, D. B.

    2013-05-31

    Transparent p-type materials with good mobility are needed to build completely transparent p-n junctions. Tin monoxide (SnO) is a promising candidate. A recent study indicates great enhancement of the hole mobility of SnO grown in Sn-rich environment [E. Fortunato et al., Appl. Phys. Lett. 97, 052105 (2010)]. Because such an environment makes the formation of defects very likely, we study defect effects on the electronic structure to explain the increased mobility. We find that Sn interstitials and O vacancies modify the valence band, inducing higher contributions of the delocalized Sn 5p orbitals as compared to the localized O 2p orbitals, thus increasing the mobility. This mechanism of valence band modification paves the way to a systematic improvement of transparent p-type semiconductors.

  6. Growth and characteristics of p-type doped GaAs nanowire

    Science.gov (United States)

    Li, Bang; Yan, Xin; Zhang, Xia; Ren, Xiaomin

    2018-05-01

    The growth of p-type GaAs nanowires (NWs) on GaAs (111) B substrates by metal-organic chemical vapor deposition (MOCVD) has been systematically investigated as a function of diethyl zinc (DEZn) flow. The growth rate of GaAs NWs was slightly improved by Zn-doping and kink is observed under high DEZn flow. In addition, the I–V curves of GaAs NWs has been measured and the p-type dope concentration under the II/III ratio of 0.013 and 0.038 approximated to 1019–1020 cm‑3. Project supported by the National Natural Science Foundation of China (Nos. 61376019, 61504010, 61774021) and the Fund of State Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), China (Nos. IPOC2017ZT02, IPOC2017ZZ01).

  7. A Density Functional Theory Study of Doped Tin Monoxide as a Transparent p-type Semiconductor

    KAUST Repository

    Bianchi Granato, Danilo

    2012-05-01

    In the pursuit of enhancing the electronic properties of transparent p-type semiconductors, this work uses density functional theory to study the effects of doping tin monoxide with nitrogen, antimony, yttrium and lanthanum. An overview of the theoretical concepts and a detailed description of the methods employed are given, including a discussion about the correction scheme for charged defects proposed by Freysoldt and others [Freysoldt 2009]. Analysis of the formation energies of the defects points out that nitrogen substitutes an oxygen atom and does not provide charge carriers. On the other hand, antimony, yttrium, and lanthanum substitute a tin atom and donate n-type carriers. Study of the band structure and density of states indicates that yttrium and lanthanum improves the hole mobility. Present results are in good agreement with available experimental works and help to improve the understanding on how to engineer transparent p-type materials with higher hole mobilities.

  8. Effect of compressive stress on stability of N-doped p-type ZnO

    International Nuclear Information System (INIS)

    Chen Xingyou; Zhang Zhenzhong; Jiang Mingming; Wang Shuangpeng; Li Binghui; Shan Chongxin; Liu Lei; Zhao Dongxu; Shen Dezhen; Yao Bin

    2011-01-01

    Nitrogen-doped p-type zinc oxide (p-ZnO:N) thin films were fabricated on a-/c-plane sapphire (a-/c-Al 2 O 3 ) by plasma-assisted molecular beam epitaxy. Hall-effect measurements show that the p-type ZnO:N on c-Al 2 O 3 degenerated into n-type after a preservation time; however, the one grown on a-Al 2 O 3 showed good stability. The conversion of conductivity in the one grown on c-Al 2 O 3 ascribed to the faster disappearance of N O and the growing N 2(O) , which is demonstrated by x-ray photoelectron spectroscopy (XPS). Compressive stress, caused by lattice misfit, was revealed by Raman spectra and optical absorption spectra, and it was regarded as the root of the instability in ZnO:N.

  9. Highly conducting p-type nanocrystalline silicon thin films preparation without additional hydrogen dilution

    Science.gov (United States)

    Patra, Chandralina; Das, Debajyoti

    2018-04-01

    Boron doped nanocrystalline silicon thin film has been successfully prepared at a low substrate temperature (250 °C) in planar inductively coupled RF (13.56 MHz) plasma CVD, without any additional hydrogen dilution. The effect of B2H6 flow rate on structural and electrical properties of the films has been studied. The p-type nc-Si:H films prepared at 5 ≤ B2H6 (sccm) ≤ 20 retains considerable amount of nanocrystallites (˜80 %) with high conductivity ˜101 S cm-1 and dominant crystallographic orientation which has been correlated with the associated increased ultra- nanocrystalline component in the network. Such properties together make the material significantly effective for utilization as p-type emitter layer in heterojunction nc-Si solar cells.

  10. Variation of minority charge carrier lifetime in high-resistance p-type silicon under irradiation

    International Nuclear Information System (INIS)

    Basheleishvili, Z.V.; Garnyk, V.S.; Gorin, S.N.; Pagava, T.A.

    1984-01-01

    The minority carrier lifetime (tau) variation was studied in the process of p-type silicon bombardment with fast 8 MeV electrons. The irradiation and all measurements were carried out at room temperature. The tau quantity was measured by the photoconductivity attenuation method at a low injection level 20% measurement error; the resistivity was measured by the four-probe method (10% error). The resistivity and minority charge carrier lifetime tau are shown to increase with the exposure dose. It is supposed that as radiation dose increases, the rearrangement of the centres responsible for reducing the lifetime occurs and results in a tau increase in the material being irradiated, however the tau value observed in the original samples is not attained. The restoration of the minority carrier lifetime in p-type high-resistance silicon with a growing exposure dose might proceed due to reduction in the free carrier concentration

  11. Piezoelectric Nanogenerator Using p-Type ZnO Nanowire Arrays

    KAUST Repository

    Lu, Ming-Pei

    2009-03-11

    Using phosphorus-doped ZnO nanowire (NW) arrays grown on silicon substrate, energy conversion using the p-type ZnO NWs has been demonstrated for the first time. The p-type ZnO NWs produce positive output voltage pulses when scanned by a conductive atomic force microscope (AFM) in contact mode. The output voltage pulse is generated when the tip contacts the stretched side (positive piezoelectric potential side) of the NW. In contrast, the n-type ZnO NW produces negative output voltage when scanned by the AFM tip, and the output voltage pulse is generated when the tip contacts the compressed side (negative potential side) of the NW. In reference to theoretical simulation, these experimentally observed phenomena have been systematically explained based on the mechanism proposed for a nanogenerator. © 2009 American Chemical Society.

  12. CCE measurements and annealing studies on proton-irradiated p-type MCz silicon diodes

    CERN Document Server

    Hoedlmoser, H; Köhler, M; Nordlund, H

    2007-01-01

    Magnetic Czochralski (MCz) silicon has recently been investigated for the development of radiation tolerant detectors for future high-luminosity HEP experiments. A study of p-type MCz Silicon diodes irradiated with protons up to a fluence of has been performed by means of Charge Collection Efficiency (CCE) measurements as well as standard CV/IV characterizations. The changes of CCE, full depletion voltage and leakage current as a function of fluence are reported. A subsequent annealing study of the irradiated detectors shows an increase in effective doping concentration and a decrease in the leakage current, whereas the CCE remains basically unchanged. Two different series of detectors have been compared differing in the implantation dose of p-spray isolation as well as effective doping concentration (Neff) of the p-type bulk presumably due to a difference in thermal donor (TD) activation during processing. The series with the higher concentration of TDs shows a delayed reverse annealing of Neff after irradia...

  13. CALCULATING THE HABITABLE ZONE OF BINARY STAR SYSTEMS. II. P-TYPE BINARIES

    International Nuclear Information System (INIS)

    Haghighipour, Nader; Kaltenegger, Lisa

    2013-01-01

    We have developed a comprehensive methodology for calculating the circumbinary habitable zone (HZ) in planet-hosting P-type binary star systems. We present a general formalism for determining the contribution of each star of the binary to the total flux received at the top of the atmosphere of an Earth-like planet and use the Sun's HZ to calculate the inner and outer boundaries of the HZ around a binary star system. We apply our calculations to the Kepler's currently known circumbinary planetary systems and show the combined stellar flux that determines the boundaries of their HZs. We also show that the HZ in P-type systems is dynamic and, depending on the luminosity of the binary stars, their spectral types, and the binary eccentricity, its boundaries vary as the stars of the binary undergo their orbital motion. We present the details of our calculations and discuss the implications of the results

  14. CALCULATING THE HABITABLE ZONE OF BINARY STAR SYSTEMS. II. P-TYPE BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Haghighipour, Nader [Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii-Manoa, Honolulu, HI 96822 (United States); Kaltenegger, Lisa [MPIA, Koenigstuhl 17, Heidelberg, D-69117 (Germany)

    2013-11-10

    We have developed a comprehensive methodology for calculating the circumbinary habitable zone (HZ) in planet-hosting P-type binary star systems. We present a general formalism for determining the contribution of each star of the binary to the total flux received at the top of the atmosphere of an Earth-like planet and use the Sun's HZ to calculate the inner and outer boundaries of the HZ around a binary star system. We apply our calculations to the Kepler's currently known circumbinary planetary systems and show the combined stellar flux that determines the boundaries of their HZs. We also show that the HZ in P-type systems is dynamic and, depending on the luminosity of the binary stars, their spectral types, and the binary eccentricity, its boundaries vary as the stars of the binary undergo their orbital motion. We present the details of our calculations and discuss the implications of the results.

  15. Charge collection measurements with p-type Magnetic Czochralski silicon single pad detectors

    International Nuclear Information System (INIS)

    Tosi, C.; Bruzzi, M.; Macchiolo, A.; Scaringella, M.; Petterson, M.K.; Sadrozinski, H.F.-W.; Betancourt, C.; Manna, N.; Creanza, D.; Boscardin, M.; Piemonte, C.; Zorzi, N.; Borrello, L.; Messineo, A.

    2007-01-01

    The charge collected from beta source particles in single pad detectors produced on p-type Magnetic Czochralski (MCz) silicon wafers has been measured before and after irradiation with 26 MeV protons. After a 1 MeV neutron equivalent fluence of 1x10 15 cm -2 the collected charge is reduced to 77% at bias voltages below 900 V. This result is compared with previous results from charge collection measurements

  16. Doping process of p-type GaN nanowires: A first principle study

    Science.gov (United States)

    Xia, Sihao; Liu, Lei; Diao, Yu; Feng, Shu

    2017-10-01

    The process of p-type doping for GaN nanowires is investigated using calculations starting from first principles. The influence of different doping elements, sites, types, and concentrations is discussed. Results suggest that Mg is an optimal dopant when compared to Be and Zn due to its stronger stability, whereas Be atoms are more inclined to exist in the interspace of a nanowire. Interstitially-doped GaN nanowires show notable n-type conductivity, and thus, Be is not a suitable dopant, which is to be expected since systems with inner substitutional dopants are more favorable than those with surface substitutions. Both interstitial and substitutional doping affect the atomic structure near dopants and induce charge transfer between the dopants and adjacent atoms. By altering doping sites and concentrations, nanowire atomic structures remain nearly constant. Substitutional doping models show p-type conductivity, and Mg-doped nanowires with doping concentrations of 4% showing the strongest p-type conductivity. All doping configurations are direct bandgap semiconductors. This study is expected to direct the preparation of high-quality GaN nanowires.

  17. Prospects and limitations for p-type doping in boron nitride polymorphs

    Science.gov (United States)

    Weston, Leigh; van de Walle, Chris G.

    Using first-principles calculations, we examine the potential for p-type doping of BN polymorphs via substitutional impurities. Based on density functional theory with a hybrid functional, our calculations reveal that group-IV elements (C, Si) substituting at the N site result in acceptor levels that are more than 1 eV above the valence-band maximum in all of the BN polymorphs, and hence far too deep to allow for p-type doping. On the other hand, group-II elements (Be, Mg) substituting at the B site lead to shallower acceptor levels. However, for the ground-state hexagonal phase (h-BN), we show that p-type doping at the B site is inhibited by the formation of hole polarons. Our calculations reveal that hole localization is intrinsic to sp2 bonded h-BN, and this places fundamental limits on hole conduction in this material. In contrast, the sp3 bonded wurtzite (w-BN) and cubic (c-BN) polymorphs are capable of forming shallow acceptor levels. For Be dopants, the acceptor ionization energies are 0.31 eV and 0.24 eV for w-BN and c-BN, respectively; these values are only slightly larger than the ionization energy of the Mg acceptor in GaN. This work was supported by NSF.

  18. Optical and electrical properties of CuMO2 transparent p-type conductors

    Science.gov (United States)

    Draeseke, A. D.; Jayaraj, M. K.; Ulbrich, T.; Kroupp, M.; Tate, J.; Nagarajan, R.; Oblezov, A.; Sleight, A. W.

    2001-03-01

    Wide band gap oxides of the type CuMO2 with the delafossite structure are p-type conductors and many of them are transparent. Films of these p-type oxides have been grown by sputtering and thermal evaporation, and characterized electrically and optically. We present transport and optical transmission measurements for CuY_1-xCa_xO_2, CuScO_2+x and other similar materials. Conductivities are in the range 1 200 S/cm and depend on details of film preparation. The carriers are p-type as determined by thermopower measurements, and typical Seebeck coefficients are several hundred µV/K. Optical transparency varies considerably, but is about 40% at 550 nm for the highest conductivity films. Excellent transparency can be achieved at the expense of conductivity, and optimization is being studied. Band gaps derived from optical transmission are larger than 3.1 eV. Prototype all-oxide pn diodes have been fabricated. This work was partially supported by the NSF under DMR-0071727 and by the Research Corporation under RA0291.

  19. Record mobility in transparent p-type tin monoxide films and devices by phase engineering

    KAUST Repository

    Caraveo-Frescas, Jesus Alfonso

    2013-06-25

    Here, we report the fabrication of nanoscale (15 nm) fully transparent p-type SnO thin film transistors (TFT) at temperatures as low as 180 C with record device performance. Specifically, by carefully controlling the process conditions, we have developed SnO thin films with a Hall mobility of 18.71 cm2 V-1 s-1 and fabricated TFT devices with a linear field-effect mobility of 6.75 cm2 V-1 s -1 and 5.87 cm2 V-1 s-1 on transparent rigid and translucent flexible substrates, respectively. These values of mobility are the highest reported to date for any p-type oxide processed at this low temperature. We further demonstrate that this high mobility is realized by careful phase engineering. Specifically, we show that phase-pure SnO is not necessarily the highest mobility phase; instead, well-controlled amounts of residual metallic tin are shown to substantially increase the hole mobility. A detailed phase stability map for physical vapor deposition of nanoscale SnO is constructed for the first time for this p-type oxide. © 2013 American Chemical Society.

  20. Linear and Nonlinear Rheology Combined with Dielectric Spectroscopy of Hybrid Polymer Nanocomposites for Semiconductive Applications

    Science.gov (United States)

    Kádár, Roland; Abbasi, Mahdi; Figuli, Roxana; Rigdahl, Mikael; Wilhelm, Manfred

    2017-01-01

    The linear and nonlinear oscillatory shear, extensional and combined rheology-dielectric spectroscopy of hybrid polymer nanocomposites for semiconductive applications were investigated in this study. The main focus was the influence of processing conditions on percolated poly(ethylene-butyl acrylate) (EBA) nanocomposite hybrids containing graphite nanoplatelets (GnP) and carbon black (CB). The rheological response of the samples was interpreted in terms of dispersion properties, filler distortion from processing, filler percolation, as well as the filler orientation and distribution dynamics inside the matrix. Evidence of the influence of dispersion properties was found in linear viscoelastic dynamic frequency sweeps, while the percolation of the nanocomposites was detected in nonlinearities developed in dynamic strain sweeps. Using extensional rheology, hybrid samples with better dispersion properties lead to a more pronounced strain hardening behavior, while samples with a higher volume percentage of fillers caused a drastic reduction in strain hardening. The rheo-dielectric time-dependent response showed that in the case of nanocomposites containing only GnP, the orientation dynamics leads to non-conductive samples. However, in the case of hybrids, the orientation of the GnP could be offset by the dispersing of the CB to bridge the nanoplatelets. The results were interpreted in the framework of a dual PE-BA model, where the fillers would be concentrated mainly in the BA regions. Furthermore, better dispersed hybrids obtained using mixing screws at the expense of filler distortion via extrusion processing history were emphasized through the rheo-dielectric tests. PMID:28336857

  1. Semiconducting icosahedral boron arsenide crystal growth for neutron detection

    Science.gov (United States)

    Whiteley, C. E.; Zhang, Y.; Gong, Y.; Bakalova, S.; Mayo, A.; Edgar, J. H.; Kuball, M.

    2011-03-01

    Semiconducting icosahedral boron arsenide, B12As2, is an excellent candidate for neutron detectors, thermoelectric converters, and radioisotope batteries, for which high quality single crystals are required. Thus, the present study was undertaken to grow B12As2 crystals by precipitation from metal solutions (nickel) saturated with elemental boron (or B12As2 powder) and arsenic in a sealed quartz ampoule. B12As2 crystals of 10-15 mm were produced when a homogeneous mixture of the three elements was held at 1150 °C for 48-72 h and slowly cooled (3.5 °C/h). The crystals varied in color and transparency from black and opaque to clear and transparent. X-ray topography (XRT), and elemental analysis by energy dispersive X-ray spectroscopy (EDS) confirmed that the crystals had the expected rhombohedral structure and chemical stoichiometry. The concentrations of residual impurities (nickel, carbon, etc.) were low, as measured by Raman spectroscopy and secondary ion mass spectrometry (SIMS). Additionally, low etch-pit densities (4.4×107 cm-2) were observed after etching in molten KOH at 500 °C. Thus, the flux growth method is viable for growing large, high-quality B12As2 crystals.

  2. Meso-/Nanoporous Semiconducting Metal Oxides for Gas Sensor Applications

    Directory of Open Access Journals (Sweden)

    Nguyen Duc Hoa

    2015-01-01

    Full Text Available Development and/or design of new materials and/or structures for effective gas sensor applications with fast response and high sensitivity, selectivity, and stability are very important issues in the gas sensor technology. This critical review introduces our recent progress in the development of meso-/nanoporous semiconducting metal oxides and their applications to gas sensors. First, the basic concepts of resistive gas sensors and the recent synthesis of meso-/nanoporous metal oxides for gas sensor applications are introduced. The advantages of meso-/nanoporous metal oxides are also presented, taking into account the crystallinity and ordered/disordered porous structures. Second, the synthesis methods of meso-/nanoporous metal oxides including the soft-template, hard-template, and temple-free methods are introduced, in which the advantages and disadvantages of each synthetic method are figured out. Third, the applications of meso-/nanoporous metal oxides as gas sensors are presented. The gas nanosensors are designed based on meso-/nanoporous metal oxides for effective detection of toxic gases. The sensitivity, selectivity, and stability of the meso-/nanoporous gas nanosensors are also discussed. Finally, some conclusions and an outlook are presented.

  3. Gas Sensors Based on Semiconducting Nanowire Field-Effect Transistors

    Directory of Open Access Journals (Sweden)

    Ping Feng

    2014-09-01

    Full Text Available One-dimensional semiconductor nanostructures are unique sensing materials for the fabrication of gas sensors. In this article, gas sensors based on semiconducting nanowire field-effect transistors (FETs are comprehensively reviewed. Individual nanowires or nanowire network films are usually used as the active detecting channels. In these sensors, a third electrode, which serves as the gate, is used to tune the carrier concentration of the nanowires to realize better sensing performance, including sensitivity, selectivity and response time, etc. The FET parameters can be modulated by the presence of the target gases and their change relate closely to the type and concentration of the gas molecules. In addition, extra controls such as metal decoration, local heating and light irradiation can be combined with the gate electrode to tune the nanowire channel and realize more effective gas sensing. With the help of micro-fabrication techniques, these sensors can be integrated into smart systems. Finally, some challenges for the future investigation and application of nanowire field-effect gas sensors are discussed.

  4. Failure mechanisms and electromechanical coupling in semiconducting nanowires

    Directory of Open Access Journals (Sweden)

    Peng B.

    2010-06-01

    Full Text Available One dimensional nanostructures, like nanowires and nanotubes, are increasingly being researched for the development of next generation devices like logic gates, transistors, and solar cells. In particular, semiconducting nanowires with a nonsymmetric wurtzitic crystal structure, such as zinc oxide (ZnO and gallium nitride (GaN, have drawn immense research interests due to their electromechanical coupling. The designing of the future nanowire-based devices requires component-level characterization of individual nanowires. In this paper, we present a unique experimental set-up to characterize the mechanical and electromechanical behaviour of individual nanowires. Using this set-up and complementary atomistic simulations, mechanical properties of ZnO nanowires and electromechanical properties of GaN nanowires were investigated. In ZnO nanowires, elastic modulus was found to depend on nanowire diameter decreasing from 190 GPa to 140 GPa as the wire diameter increased from 5 nm to 80 nm. Inconsistent failure mechanisms were observed in ZnO nanowires. Experiments revealed a brittle fracture, whereas simulations using a pairwise potential predicted a phase transformation prior to failure. This inconsistency is addressed in detail from an experimental as well as computational perspective. Lastly, in addition to mechanical properties, preliminary results on the electromechanical properties of gallium nitride nanowires are also reported. Initial investigations reveal that the piezoresistive and piezoelectric behaviour of nanowires is different from bulk gallium nitride.

  5. Nonlinear transport in semiconducting polymers at high carrier densities.

    Science.gov (United States)

    Yuen, Jonathan D; Menon, Reghu; Coates, Nelson E; Namdas, Ebinazar B; Cho, Shinuk; Hannahs, Scott T; Moses, Daniel; Heeger, Alan J

    2009-07-01

    Conducting and semiconducting polymers are important materials in the development of printed, flexible, large-area electronics such as flat-panel displays and photovoltaic cells. There has been rapid progress in developing conjugated polymers with high transport mobility required for high-performance field-effect transistors (FETs), beginning with mobilities around 10(-4) cm(2) V(-1) s(-1) to a recent report of 1 cm(2) V(-1) s(-1) for poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT). Here, the electrical properties of PBTTT are studied at high charge densities both as the semiconductor layer in FETs and in electrochemically doped films to determine the transport mechanism. We show that data obtained using a wide range of parameters (temperature, gate-induced carrier density, source-drain voltage and doping level) scale onto the universal curve predicted for transport in the Luttinger liquid description of the one-dimensional 'metal'.

  6. Engineering the Kondo state in two-dimensional semiconducting phosphorene

    Science.gov (United States)

    Babar, Rohit; Kabir, Mukul

    2018-01-01

    Correlated interaction between dilute localized impurity electrons and the itinerant host conduction electrons in metals gives rise to the conventional many-body Kondo effect below sufficiently low temperature. In sharp contrast to these conventional Kondo systems, we report an intrinsic, robust, and high-temperature Kondo state in two-dimensional semiconducting phosphorene. While absorbed at a thermodynamically stable lattice defect, Cr impurity triggers an electronic phase transition in phosphorene to provide conduction electrons, which strongly interact with the localized moment generated at the Cr site. These manifest into the intrinsic Kondo state, where the impurity moment is quenched in multiple stages and at temperatures in the 40-200 K range. Further, along with a much smaller extension of the Kondo cloud, the predicted Kondo state is shown to be robust under uniaxial strain and layer thickness, which greatly simplifies its future experimental realization. We predict the present study will open up new avenues in Kondo physics and trigger further theoretical and experimental studies.

  7. Advanced Branching Control and Characterization of Inorganic Semiconducting Nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Steven Michael [Univ. of California, Berkeley, CA (United States)

    2007-01-01

    The ability to finely tune the size and shape of inorganic semiconducting nanocrystals is an area of great interest, as the more control one has, the more applications will be possible for their use. The first two basic shapes develped in nanocrystals were the sphere and the anistropic nanorod. the II_VI materials being used such as Cadmium Selenide (CdSe) and Cadmium Telluride (CdTe), exhibit polytypism, which allows them to form in either the hexagonally packed wurtzite or cubically packed zinc blende crystalline phase. The nanorods are wurtzite with the length of the rod growing along the c-axis. As this grows, stacking faults may form, which are layers of zinc blende in the otherwise wurtzite crystal. Using this polytypism, though, the first generation of branched crystals were developed in the form of the CdTe tetrapod. This is a nanocrystal that nucleates in the zincblend form, creating a tetrahedral core, on which four wurtzite arms are grown. This structure opened up the possibility of even more complex shapes and applications. This disseration investigates the advancement of branching control and further understanding the materials polytypism in the form of the stacking faults in nanorods.

  8. A study of transition from n- to p-type based on hexagonal WO3 nanorods sensor

    Science.gov (United States)

    Wu, Ya-Qiao; Hu, Ming; Wei, Xiao-Ying

    2014-04-01

    Hexagonal WO3 nanorods are fabricated by a facile hydrothermal process at 180 °C using sodium tungstate and sodium chloride as starting materials. The morphology, structure, and composition of the prepared nanorods are studied by scanning electron microscopy, X-ray diffraction spectroscopy, and energy dispersive spectroscopy. It is found that the agglomeration of the nanorods is strongly dependent on the PH value of the reaction solution. Uniform and isolated WO3 nanorods with diameters ranging from 100 nm-150 nm and lengths up to several micrometers are obtained at PH = 2.5 and the nanorods are identified as being hexagonal in phase structure. The sensing characteristics of the WO3 nanorod sensor are obtained by measuring the dynamic response to NO2 with concentrations in the range 0.5 ppm-5 ppm and at working temperatures in the range 25 °C-250 °C. The obtained WO3 nanorods sensors are found to exhibit opposite sensing behaviors, depending on the working temperature. When being exposed to oxidizing NO2 gas, the WO3 nanorod sensor behaves as an n-type semiconductor as expected when the working temperature is higher than 50 °C, whereas, it behaves as a p-type semiconductor below 50 °C. The origin of the n- to p-type transition is correlated with the formation of an inversion layer at the surface of the WO3 nanorod at room temperature. This finding is useful for making new room temperature NO2 sensors based on hexagonal WO3 nanorods.

  9. A study of transition from n- to p-type based on hexagonal WO3 nanorods sensor

    International Nuclear Information System (INIS)

    Wu Ya-Qiao; Hu Ming; Wei Xiao-Ying

    2014-01-01

    Hexagonal WO 3 nanorods are fabricated by a facile hydrothermal process at 180 °C using sodium tungstate and sodium chloride as starting materials. The morphology, structure, and composition of the prepared nanorods are studied by scanning electron microscopy, X-ray diffraction spectroscopy, and energy dispersive spectroscopy. It is found that the agglomeration of the nanorods is strongly dependent on the PH value of the reaction solution. Uniform and isolated WO 3 nanorods with diameters ranging from 100 nm–150 nm and lengths up to several micrometers are obtained at PH = 2.5 and the nanorods are identified as being hexagonal in phase structure. The sensing characteristics of the WO 3 nanorod sensor are obtained by measuring the dynamic response to NO 2 with concentrations in the range 0.5 ppm–5 ppm and at working temperatures in the range 25 °C–250 °C. The obtained WO 3 nanorods sensors are found to exhibit opposite sensing behaviors, depending on the working temperature. When being exposed to oxidizing NO 2 gas, the WO 3 nanorod sensor behaves as an n-type semiconductor as expected when the working temperature is higher than 50 °C, whereas, it behaves as a p-type semiconductor below 50 °C. The origin of the n- to p-type transition is correlated with the formation of an inversion layer at the surface of the WO 3 nanorod at room temperature. This finding is useful for making new room temperature NO 2 sensors based on hexagonal WO 3 nanorods. (general)

  10. Room temperature p-type conductivity and coexistence of ferroelectric order in ferromagnetic Li doped ZnO nanoparticles

    KAUST Repository

    Awan, Saif Ullah

    2014-10-28

    Memory and switching devices acquired new materials which exhibit ferroelectric and ferromagnetic order simultaneously. We reported multiferroic behavior in Zn1-yLiyO(0.00≤y≤0.10) nanoparticles. The analysis of transmission electron micrographs confirmed the hexagonal morphology and wurtzite crystalline structure. We investigated p-type conductivity in doped samples and measured hole carriers in range 2.4×1017/cc to 7.3×1017/cc for different Li contents. We found that hole carriers are responsible for long range order ferromagnetic coupling in Li doped samples. Room temperature ferroelectric hysteresis loops were observed in 8% and 10% Li doped samples. We demonstrated ferroelectric coercivity (remnant polarization) 2.5kV/cm (0.11 μC/cm2) and 2.8kV/cm (0.15 μC/cm2) for y=0.08 and y=0.10 samples. We propose that the mechanism of Li induced ferroelectricity in ZnO is due to indirect dipole interaction via hole carriers. We investigated that if the sample has hole carriers ≥5.3×1017/cc, they can mediate the ferroelectricity. Ferroelectric and ferromagnetic measurements showed that higher electric polarization and larger magnetic moment is attained when the hole concentration is larger and vice versa. Our results confirmed the hole dependent coexistence of ferromagnetic and ferroelectric behavior at room temperature, which provide potential applications for switchable and memory devices.

  11. Semiconducting double-dot exchange-only qubit dynamics in the presence of magnetic and charge noises

    Science.gov (United States)

    Ferraro, E.; Fanciulli, M.; De Michielis, M.

    2018-06-01

    The effects of magnetic and charge noises on the dynamical evolution of the double-dot exchange-only qubit (DEOQ) is theoretically investigated. The DEOQ consisting of three electrons arranged in an electrostatically defined double quantum dot deserves special interest in quantum computation applications. Its advantages are in terms of fabrication, control and manipulation in view of implementation of fast single and two-qubit operations through only electrical tuning. The presence of the environmental noise due to nuclear spins and charge traps, in addition to fluctuations in the applied magnetic field and charge fluctuations on the electrostatic gates adopted to confine the electrons, is taken into account including random magnetic field and random coupling terms in the Hamiltonian. The behavior of the return probability as a function of time for initial conditions of interest is presented. Moreover, through an envelope-fitting procedure on the return probabilities, coherence times are extracted when model parameters take values achievable experimentally in semiconducting devices.

  12. Flow induced/ refined solution crystallization of a semiconducting polymer

    Science.gov (United States)

    Nguyen, Ngoc A.

    Organic photovoltaics, a new generation of solar cells, has gained scientific and economic interests due to the ability of solution-processing and potentially low-cost power production. Though, the low power conversion efficiency of organic/ plastic solar cells is one of the most pertinent challenges that has appealed to research communities from many different fields including materials science and engineering, electrical engineering, chemical engineering, physics and chemistry. This thesis focuses on investigating and controlling the morphology of a semi-conducting, semi-crystalline polymer formed under shear-flow. Molecular structures and processing techniques are critical factors that significantly affect the morphology formation in the plastic solar cells, thus influencing device performance. In this study, flow-induced solution crystallization of poly (3-hexylthiophene) (P3HT) in a poor solvent, 2-ethylnapthalene (2-EN) was utilized to make a paint-like, structural liquid. The polymer crystals observed in this structured paint are micrometers long, nanometers in cross section and have a structure similar to that formed under quiescent conditions. There is pi-pi stacking order along the fibril axis, while polymer chain folding occurs along the fibril width and the order of the side-chain stacking is along fibril height. It was revealed that shear-flow not only induces P3HT crystallization from solution, but also refines and perfects the P3HT crystals. Thus, a general strategy to refine the semiconducting polymer crystals from solution under shear-flow has been developed and employed by simply tuning the processing (shearing) conditions with respect to the dissolution temperature of P3HT in 2-EN. The experimental results demonstrated that shear removes defects and allows more perfect crystals to be formed. There is no glass transition temperature observed in the crystals formed using the flow-induced crystallization indicating a significantly different

  13. Intrinsically stretchable and healable semiconducting polymer for organic transistors.

    Science.gov (United States)

    Oh, Jin Young; Rondeau-Gagné, Simon; Chiu, Yu-Cheng; Chortos, Alex; Lissel, Franziska; Wang, Ging-Ji Nathan; Schroeder, Bob C; Kurosawa, Tadanori; Lopez, Jeffrey; Katsumata, Toru; Xu, Jie; Zhu, Chenxin; Gu, Xiaodan; Bae, Won-Gyu; Kim, Yeongin; Jin, Lihua; Chung, Jong Won; Tok, Jeffrey B-H; Bao, Zhenan

    2016-11-17

    Thin-film field-effect transistors are essential elements of stretchable electronic devices for wearable electronics. All of the materials and components of such transistors need to be stretchable and mechanically robust. Although there has been recent progress towards stretchable conductors, the realization of stretchable semiconductors has focused mainly on strain-accommodating engineering of materials, or blending of nanofibres or nanowires into elastomers. An alternative approach relies on using semiconductors that are intrinsically stretchable, so that they can be fabricated using standard processing methods. Molecular stretchability can be enhanced when conjugated polymers, containing modified side-chains and segmented backbones, are infused with more flexible molecular building blocks. Here we present a design concept for stretchable semiconducting polymers, which involves introducing chemical moieties to promote dynamic non-covalent crosslinking of the conjugated polymers. These non-covalent crosslinking moieties are able to undergo an energy dissipation mechanism through breakage of bonds when strain is applied, while retaining high charge transport abilities. As a result, our polymer is able to recover its high field-effect mobility performance (more than 1 square centimetre per volt per second) even after a hundred cycles at 100 per cent applied strain. Organic thin-film field-effect transistors fabricated from these materials exhibited mobility as high as 1.3 square centimetres per volt per second and a high on/off current ratio exceeding a million. The field-effect mobility remained as high as 1.12 square centimetres per volt per second at 100 per cent strain along the direction perpendicular to the strain. The field-effect mobility of damaged devices can be almost fully recovered after a solvent and thermal healing treatment. Finally, we successfully fabricated a skin-inspired stretchable organic transistor operating under deformations that might be

  14. Thermoelectric performance of tellurium-reduced quaternary p-type lead–chalcogenide composites

    International Nuclear Information System (INIS)

    Aminorroaya Yamini, Sima; Wang, Heng; Gibbs, Zachary M.; Pei, Yanzhong; Mitchell, David R.G.; Dou, Shi Xue; Snyder, G. Jeffrey

    2014-01-01

    Graphical abstract: - Abstract: A long-standing technological challenge to the widespread application of thermoelectric generators is obtaining high-performance thermoelectric materials from abundant elements. Intensive study on PbTe alloys has resulted in a high figure of merit for the single-phase ternary PbTe–PbSe system through band structure engineering, and the low thermal conductivity achieved due to nanostructuring leads to high thermoelectric performance for ternary PbTe–PbS compounds. Recently, the single-phase p-type quaternary PbTe–PbSe–PbS alloys have been shown to provide thermoelectric performance superior to the binary and ternary lead chalcogenides. This occurs via tuning of the band structure and from an extraordinary low thermal conductivity resulting from high-contrast atomic mass solute atoms. Here, we present the thermoelectric efficiency of nanostructured p-type quaternary PbTe–PbSe–PbS composites and compare the results with corresponding single-phase quaternary lead chalcogenide alloys. We demonstrate that the very low lattice thermal conductivity achieved is attributed to phonon scattering at high-contrast atomic mass solute atoms rather than from the contribution of secondary phases. This results in a thermoelectric efficiency of ∼1.4 over a wide temperature range (650–850 K) in a p-type quaternary (PbTe) 0.65 (PbSe) 0.1 (PbS) 0.25 composite that is lower than that of single-phase (PbTe) 0.85 (PbSe) 0.1 (PbS) 0.05 alloy without secondary phases

  15. Characteristics of accumulation of recombination centers due to irradiation of p-type Si

    International Nuclear Information System (INIS)

    Kazakevich, L.A.; Lugakov, P.F.; Filippov, I.M.

    1989-01-01

    Irradiation of Czochralski-grown p-type Si single crystals results primarily in creation of recombination-active radiation defects which give rise to a donor energy level at E v + 0.30-0.38 eV in the band gap. The ideas on the structure and mechanisms of formation of these radiation defects are continuously evolving and at present the most widely held view is that which assumes that the K centers can be carbon-oxygen-divacancy complexes or interstitial carbon-interstitial oxygen pairs. The authors investigated the recombination properties of such centers

  16. Photovoltaic properties of ZnO nanorods/p-type Si heterojunction structures

    Directory of Open Access Journals (Sweden)

    Rafal Pietruszka

    2014-02-01

    Full Text Available Selected properties of photovoltaic (PV structures based on n-type zinc oxide nanorods grown by a low temperature hydrothermal method on p-type silicon substrates (100 are investigated. PV structures were covered with thin films of Al doped ZnO grown by atomic layer deposition acting as transparent electrodes. The investigated PV structures differ in terms of the shapes and densities of their nanorods. The best response is observed for the structure containing closely-spaced nanorods, which show light conversion efficiency of 3.6%.

  17. P-Type Silicon Strip Sensors for the Future CMS Tracker

    CERN Document Server

    The Tracker Group of the CMS Collaboration

    2016-01-01

    The upgrade to the High-Luminosity LHC (HL-LHC) is expected to increase the LHC design luminosity by an order of magnitude. This will require silicon tracking detectors with a significantly higher radiation hardness. The CMS Tracker Collaboration has conducted an irradiation and measurement campaign to identify suitable silicon sensor materials and strip designs for the future outer tracker at CMS. Based on these results, the collaboration has chosen to use n-in-p type strip and macro-pixel sensors and focus further investigations on the optimization of that sensor type. This paper describes the main measurement results and conclusions that motivated this decision.

  18. Transient expression of P-type ATPases in tobacco epidermal cells

    DEFF Research Database (Denmark)

    Pedas, Lisbeth Rosager; Palmgren, Michael Broberg; Lopez Marques, Rosa Laura

    2016-01-01

    Transient expression in tobacco cells is a convenient method for several purposes such as analysis of protein-protein interactions and the subcellular localization of plant proteins. A suspension of Agrobacterium tumefaciens cells carrying the plasmid of interest is injected into the intracellula...... for example protein-protein interaction studies. In this chapter, we describe the procedure to transiently express P-type ATPases in tobacco epidermal cells, with focus on subcellular localization of the protein complexes formed by P4-ATPases and their β-subunits....

  19. The feasibility of tunable p-type Mg doping in a GaN monolayer nanosheet

    International Nuclear Information System (INIS)

    Xia, Congxin; Peng, Yuting; Wei, Shuyi; Jia, Yu

    2013-01-01

    Based on density functional theory, the electronic structures, formation energy and transition energy level of a p-type Mg-doped GaN nanosheet are investigated. Numerical results show that the transition energy level decreases monotonously with increasing Mg doping concentration in Mg-doped GaN nanosheet systems, which is lower than that of the Mg-doped bulk GaN case. Moreover, the formation energy calculations indicate that Mg-doped GaN nanosheet structures can be realized under N-rich experimental growth conditions

  20. The development of p-type silicon detectors for the high radiation regions of the LHC

    International Nuclear Information System (INIS)

    Hanlon, M.D.L.

    1998-04-01

    This thesis describes the production and characterisation of silicon microstrip detectors and test structures on p-type substrates. An account is given of the production and full parameterisation of a p-type microstrip detector, incorporating the ATLAS-A geometry in a beam test. This detector is an AC coupled device incorporating a continuous p-stop isolation frame and polysilicon biasing and is typical of n-strip devices proposed for operation at the LHC. It was successfully read out using the FELix-128 analogue pipeline chip and a signal to noise (s/n) of 17±1 is reported, along with a spatial resolution of 14.6±0.2 μm. Diode test structures were fabricated on both high resistivity float zone material and on epitaxial material and subsequently irradiated with 24 GeV protons at the CERN PS up to a dose of (8.22±0.23) x 10 14 per cm 2 . An account of the measurement program is presented along with results on the changes in the effective doping concentration (N eff ) with irradiation and the changes in bulk current. Changes in the effective doping concentration and leakage current for high resistivity p-type material under irradiation were found to be similar to to that of n-type material. Values of α=(3.30±0.08) x 10 -17 A cm -1 for the leakage current parameter and g c =(1.20±0.05)x10 -2 cm -1 for the effective dopant introduction rate were found for this material. The epitaxial material did not perform better than the float zone material for the range of doses studied. Surprising results were obtained for highly irradiated p-type diodes illuminated on the ohmic side with an α-source, in that signals were observed well below the full depletion voltage. The processing that had been used to fabricate the test structures and the initial prototype that was studied in the test beam was based on the process used to fabricate devices on n-type material. Presented in this thesis are the modifications that were made to the process, which centred on the oxidation

  1. Initial results from 3D-DDTC detectors on p-type substrates

    Energy Technology Data Exchange (ETDEWEB)

    Zoboli, A., E-mail: zoboli@disi.unitn.i [Dipartimento di Ingegneria e Scienza dell' Informazione, Universita di Trento, and INFN, Sezione di Padova (Gruppo Collegato di Trento), Via Sommarive, 14, I-38100 Povo di Trento (Italy); Boscardin, M. [Fondazione Bruno Kessler, Centro per i Materiali e i Microsistemi, Via Sommarive, 18, I-38100 Povo di Trento (Italy); Bosisio, L. [Dipartimento di Fisica, Universita di Trieste, and INFN, Sezione di Trieste, Via A. Valerio, 2, I-34127 Trieste (Italy); Dalla Betta, G.-F. [Dipartimento di Ingegneria e Scienza dell' Informazione, Universita di Trento, and INFN, Sezione di Padova (Gruppo Collegato di Trento), Via Sommarive, 14, I-38100 Povo di Trento (Italy); Piemonte, C.; Ronchin, S.; Zorzi, N. [Fondazione Bruno Kessler, Centro per i Materiali e i Microsistemi, Via Sommarive, 18, I-38100 Povo di Trento (Italy)

    2010-01-11

    Owing to their superior radiation hardness compared to planar detectors, 3D detectors are one of the most promising technologies for the LHC upgrade foreseen in 2017. Fondazione Bruno Kessler has developed 3D Double-side Double-Type Column (3D-DDTC) detectors providing a technological simplifications with respect to a standard 3D process while aiming at comparable detector performance. We present selected results from the electrical characterization of 3D-DDTC structures from the second batch made on p-type substrates, supported also by TCAD simulations.

  2. Methods for enhancing P-type doping in III-V semiconductor films

    Science.gov (United States)

    Liu, Feng; Stringfellow, Gerald; Zhu, Junyi

    2017-08-01

    Methods of doping a semiconductor film are provided. The methods comprise epitaxially growing the III-V semiconductor film in the presence of a dopant, a surfactant capable of acting as an electron reservoir, and hydrogen, under conditions that promote the formation of a III-V semiconductor film doped with the p-type dopant. In some embodiments of the methods, the epitaxial growth of the doped III-V semiconductor film is initiated at a first hydrogen partial pressure which is increased to a second hydrogen partial pressure during the epitaxial growth process.

  3. Effect of Current Density on Thermal and Optical Properties of p-Type Porous Silicon

    International Nuclear Information System (INIS)

    Kasra Behzad; Wan Mahmood Mat Yunus; Zainal Abidin Talib; Azmi Zakaria; Afarin Bahrami

    2011-01-01

    The different parameters of the porous silicon (PSi) can be tuned by changing some parameters in preparation process. We have chosen the anodization as formation method, so the related parameters should be changed. In this study the porous silicon (PSi) layers were formed on p-type Si wafer. The samples were anodized electrically in a fixed etching time under some different current densities. The structural and optical properties of porous silicon (PSi) on silicon (Si) substrates were investigated using photoluminescence (PL) and Photoacoustic Spectroscopy (PAS). (author)

  4. Double-layered NiO photocathodes for p-type DSSCs with record IPCE

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lin; Qin, Peng; Gorlov, Mikhail [Center of Molecular Devices School of Chemical Science and Engineering, Royal Institute of Technology (KTH), Stockholm (Sweden); Gibson, Elizabeth A.; Boschloo, Gerrit [Department of Physical and Analytical Chemistry, Uppsala University (Sweden); Hagfeldt, Anders [Center of Molecular Devices School of Chemical Science and Engineering, Royal Institute of Technology (KTH), Stockholm (Sweden); Department of Physical and Analytical Chemistry, Uppsala University (Sweden); DUT-KTH Joint Education and Research Center of Molecular Devices, State Key Laboratory of Fine Chemicals, Dalian University of Technology (DUT), Dalian (China); Sun, Licheng [Center of Molecular Devices School of Chemical Science and Engineering, Royal Institute of Technology (KTH), Stockholm (Sweden); DUT-KTH Joint Education and Research Center of Molecular Devices, State Key Laboratory of Fine Chemicals, Dalian University of Technology (DUT), Dalian (China)

    2010-04-18

    A way to achieve a high-efficiency dye-sensitized solar cell is to combine an n-type TiO{sub 2}-based photoanode with a p-type photocathode in a tandem configuration. The development of an efficient photocathode is, at present, the key target. We have optimized the NiO, I{sub 3}{sup -}/I{sup -} p-DSSC system to obtain record photocurrent, giving 64% incident photon-to-current conversion efficiency (IPCE) and 5.48 mAcm{sup -2} J{sub SC}. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  5. Thermal oxidation of Ni films for p-type thin-film transistors

    KAUST Repository

    Jiang, Jie; Wang, Xinghui; Zhang, Qing; Li, Jingqi; Zhang, Xixiang

    2013-01-01

    p-Type nanocrystal NiO-based thin-film transistors (TFTs) are fabricated by simply oxidizing thin Ni films at temperatures as low as 400 °C. The highest field-effect mobility in a linear region and the current on-off ratio are found to be 5.2 cm2 V-1 s-1 and 2.2 × 103, respectively. X-ray diffraction, transmission electron microscopy and electrical performances of the TFTs with "top contact" and "bottom contact" channels suggest that the upper parts of the Ni films are clearly oxidized. In contrast, the lower parts in contact with the gate dielectric are partially oxidized to form a quasi-discontinuous Ni layer, which does not fully shield the gate electric field, but still conduct the source and drain current. This simple method for producing p-type TFTs may be promising for the next-generation oxide-based electronic applications. © 2013 the Owner Societies.

  6. Fullerene C70 as a p-type donor in organic photovoltaic cells

    International Nuclear Information System (INIS)

    Zhuang, Taojun; Wang, Xiao-Feng; Sano, Takeshi; Kido, Junji; Hong, Ziruo; Li, Gang; Yang, Yang

    2014-01-01

    Fullerenes and their derivatives have been widely used as n-type materials in organic transistor and photovoltaic devices. Though it is believed that they shall be ambipolar in nature, there have been few direct experimental proofs for that. In this work, fullerene C 70 , known as an efficient acceptor, has been employed as a p-type electron donor in conjunction with 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile as an electron acceptor in planar-heterojunction (PHJ) organic photovoltaic (OPV) cells. High fill factors (FFs) of more than 0.70 were reliably achieved with the C 70 layer even up to 100 nm thick in PHJ cells, suggesting the superior potential of fullerene C 70 as the p-type donor in comparison to other conventional donor materials. The optimal efficiency of these unconventional PHJ cells was 2.83% with a short-circuit current of 5.33 mA/cm 2 , an open circuit voltage of 0.72 V, and a FF of 0.74. The results in this work unveil the potential of fullerene materials as donors in OPV devices, and provide alternative approaches towards future OPV applications.

  7. Electronic structure and p-type doping of ZnSnN2

    Science.gov (United States)

    Wang, Tianshi; Janotti, Anderson; Ni, Chaoying

    ZnSnN2 is a promising solar-cell absorber material composed of earth abundant elements. Little is known about doping, defects, and how the valence and conduction bands in this material align with the bands in other semiconductors. Using density functional theory with the the Heyd-Scuseria-Ernzerhof hybrid functional (HSE06), we investigate the electronic structure of ZnSnN2, its band alignment to other semiconductors, such as GaN and ZnO, the possibility of p-type doping, and the possible causes of the observed unintentional n-type conductivity. We find that the position of the valence-band maximum of ZnSnN2 is 0.55 eV higher than that of GaN, yet the conduction-band minimum is close to that in ZnO. As possible p-type dopants, we explore Li, Na, and K substituting on the Zn site. Finally, we discuss the cause of unintentional n-type conductivity by analyzing the position of the conduction-band minimum with respect to that of GaN and ZnO.

  8. Impurity Resonant States p-type Doping in Wide-Band-Gap Nitrides

    Science.gov (United States)

    Liu, Zhiqiang; Yi, Xiaoyan; Yu, Zhiguo; Yuan, Gongdong; Liu, Yang; Wang, Junxi; Li, Jinmin; Lu, Na; Ferguson, Ian; Zhang, Yong

    2016-01-01

    In this work, a new strategy for achieving efficient p-type doping in high bandgap nitride semiconductors to overcome the fundamental issue of high activation energy has been proposed and investigated theoretically, and demonstrated experimentally. Specifically, in an AlxGa1-xN/GaN superlattice structure, by modulation doping of Mg in the AlxGa1-xN barriers, high concentration of holes are generated throughout the material. A hole concentration as high as 1.1 × 1018 cm-3 has been achieved, which is about one order of magnitude higher than that typically achievable by direct doping GaN. Results from first-principle calculations indicate that the coupling and hybridization between Mg 2p impurity and the host N 2p orbitals are main reasons for the generation of resonant states in the GaN wells, which further results in the high hole concentration. We expect this approach to be equally applicable for other high bandgap materials where efficient p-type doing is difficult. Furthermore, a two-carrier-species Hall-effect model is proposed to delineate and discriminate the characteristics of the bulk and 2D hole, which usually coexist in superlattice-like doping systems. The model reported here can also be used to explain the abnormal freeze-in effect observed in many previous reports.

  9. Wide band gap p-type windows by CBD and SILAR methods

    International Nuclear Information System (INIS)

    Sankapal, B.R.; Goncalves, E.; Ennaoui, A.; Lux-Steiner, M.Ch.

    2004-01-01

    Chemical deposition methods, namely, chemical bath deposition (CBD) and successive ionic layer adsorption and reaction (SILAR) have been used to deposit wide band gap p-type CuI and CuSCN thin films at room temperature (25 deg. C) in aqueous medium. Growth of these films requires the use of Cu (I) cations as a copper ions source. This is achieved by complexing Cu (II) ions using Na 2 S 2 O 3 . The anion sources are either KI as iodine or KSCN as thiocyanide ions for CuI and CuSCN films, respectively. The preparative parameters are optimized with the aim to use these p-type materials as windows for solar cells. Different substrates are used, namely: glass, fluorine doped tin oxide coated glass and CuInS 2 (CIS). X-ray diffraction, scanning electron microscopy, atomic force microscopy and optical absorption spectroscopy are used for structural, surface morphological and optical studies, and the results are discussed

  10. Effect of compressive stress on stability of N-doped p-type ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xingyou [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 3888 Dongnanhu Road, Changchun 130033 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Zhang Zhenzhong; Jiang Mingming; Wang Shuangpeng; Li Binghui; Shan Chongxin; Liu Lei; Zhao Dongxu; Shen Dezhen [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 3888 Dongnanhu Road, Changchun 130033 (China); Yao Bin [State Key Laboratory of Superhard Materials and College of Physics, Jilin University, Changchun 130023 (China)

    2011-08-29

    Nitrogen-doped p-type zinc oxide (p-ZnO:N) thin films were fabricated on a-/c-plane sapphire (a-/c-Al{sub 2}O{sub 3}) by plasma-assisted molecular beam epitaxy. Hall-effect measurements show that the p-type ZnO:N on c-Al{sub 2}O{sub 3} degenerated into n-type after a preservation time; however, the one grown on a-Al{sub 2}O{sub 3} showed good stability. The conversion of conductivity in the one grown on c-Al{sub 2}O{sub 3} ascribed to the faster disappearance of N{sub O} and the growing N{sub 2(O)}, which is demonstrated by x-ray photoelectron spectroscopy (XPS). Compressive stress, caused by lattice misfit, was revealed by Raman spectra and optical absorption spectra, and it was regarded as the root of the instability in ZnO:N.

  11. Wide band gap p-type windows by CBD and SILAR methods

    Energy Technology Data Exchange (ETDEWEB)

    Sankapal, B.R.; Goncalves, E.; Ennaoui, A.; Lux-Steiner, M.Ch

    2004-03-22

    Chemical deposition methods, namely, chemical bath deposition (CBD) and successive ionic layer adsorption and reaction (SILAR) have been used to deposit wide band gap p-type CuI and CuSCN thin films at room temperature (25 deg. C) in aqueous medium. Growth of these films requires the use of Cu (I) cations as a copper ions source. This is achieved by complexing Cu (II) ions using Na{sub 2}S{sub 2}O{sub 3}. The anion sources are either KI as iodine or KSCN as thiocyanide ions for CuI and CuSCN films, respectively. The preparative parameters are optimized with the aim to use these p-type materials as windows for solar cells. Different substrates are used, namely: glass, fluorine doped tin oxide coated glass and CuInS{sub 2} (CIS). X-ray diffraction, scanning electron microscopy, atomic force microscopy and optical absorption spectroscopy are used for structural, surface morphological and optical studies, and the results are discussed.

  12. Homogeneous Gaussian Profile P+-Type Emitters: Updated Parameters and Metal-Grid Optimization

    Directory of Open Access Journals (Sweden)

    M. Cid

    2002-10-01

    Full Text Available P+-type emitters were optimized keeping the base parameters constant. Updated internal parameters were considered. The surface recombination velocity was considered variable with the surface doping level. Passivated homogeneous emitters were found to have low emitter recombination density and high collection efficiency. A complete structure p+nn+ was analyzed, taking into account optimized shadowing and metal-contacted factors for laboratory cells as function of the surface doping level and the emitter thickness. The base parameters were kept constant to make the emitter characteristics evident. The most efficient P+-type passivated homogeneous emitters, provide efficiencies around 21% for a wide range of emitter sheet resistivity (50 -- 500 omega/ with the surface doping levels Ns=1×10(19 cm-3 and 5×10(19 cm-3. The output electrical parameters were evaluated considering the recently proposed value n i=9.65×10(9 (cm-3. A non-significant increase of 0.1% in the efficiency was obtained, validating all the conclusions obtained in this work, considering n i=1×10(10 cm-3.

  13. Synthesis and characterization of p-type boron-doped IIb diamond large single crystals

    International Nuclear Information System (INIS)

    Li Shang-Sheng; Li Xiao-Lei; Su Tai-Chao; Jia Xiao-Peng; Ma Hong-An; Huang Guo-Feng; Li Yong

    2011-01-01

    High-quality p-type boron-doped IIb diamond large single crystals are successfully synthesized by the temperature gradient method in a china-type cubic anvil high-pressure apparatus at about 5.5 GPa and 1600 K. The morphologies and surface textures of the synthetic diamond crystals with different boron additive quantities are characterized by using an optical microscope and a scanning electron microscope respectively. The impurities of nitrogen and boron in diamonds are detected by micro Fourier transform infrared technique. The electrical properties including resistivities, Hall coefficients, Hall mobilities and carrier densities of the synthesized samples are measured by a four-point probe and the Hall effect method. The results show that large p-type boron-doped diamond single crystals with few nitrogen impurities have been synthesized. With the increase of quantity of additive boron, some high-index crystal faces such as {113} gradually disappear, and some stripes and triangle pits occur on the crystal surface. This work is helpful for the further research and application of boron-doped semiconductor diamond. (cross-disciplinary physics and related areas of science and technology)

  14. Easily doped p-type, low hole effective mass, transparent oxides

    Science.gov (United States)

    Sarmadian, Nasrin; Saniz, Rolando; Partoens, Bart; Lamoen, Dirk

    2016-02-01

    Fulfillment of the promise of transparent electronics has been hindered until now largely by the lack of semiconductors that can be doped p-type in a stable way, and that at the same time present high hole mobility and are highly transparent in the visible spectrum. Here, a high-throughput study based on first-principles methods reveals four oxides, namely X2SeO2, with X = La, Pr, Nd, and Gd, which are unique in that they exhibit excellent characteristics for transparent electronic device applications - i.e., a direct band gap larger than 3.1 eV, an average hole effective mass below the electron rest mass, and good p-type dopability. Furthermore, for La2SeO2 it is explicitly shown that Na impurities substituting La are shallow acceptors in moderate to strong anion-rich growth conditions, with low formation energy, and that they will not be compensated by anion vacancies VO or VSe.

  15. The development of p-type silicon detectors for the high radiation regions of the LHC

    CERN Document Server

    Hanlon, M D L

    1998-01-01

    This thesis describes the production and characterisation of silicon microstrip detectors and test structures on p-type substrates. An account is given of the production and full parameterisation of a p-type microstrip detector, incorporating the ATLAS-A geometry in a beam test. This detector is an AC coupled device incorporating a continuous p-stop isolation frame and polysilicon biasing and is typical of n-strip devices proposed for operation at the LHC. It was successfully read out using the FELix-128 analogue pipeline chip and a signal to noise (s/n) of 17+-1 is reported, along with a spatial resolution of 14.6+-0.2 mu m. Diode test structures were fabricated on both high resistivity float zone material and on epitaxial material and subsequently irradiated with 24 GeV protons at the CERN PS up to a dose of (8.22+-0.23) x 10 sup 1 sup 4 per cm sup 2. An account of the measurement program is presented along with results on the changes in the effective doping concentration (N sub e sub f sub f) with irradiat...

  16. Use of hexamethyldisiloxane for p-type microcrystalline silicon oxycarbide layers

    Directory of Open Access Journals (Sweden)

    Goyal Prabal

    2016-01-01

    Full Text Available The use of hexamethyldisiloxane (HMDSO as an oxygen source for the growth of p-type silicon-based layers deposited by Plasma Enhanced Chemical Vapor Deposition is evaluated. The use of this source led to the incorporation of almost equivalent amounts of oxygen and carbon, resulting in microcrystalline silicon oxycarbide thin films. The layers were examined with characterisation techniques including Spectroscopic Ellipsometry, Dark Conductivity, Fourier Transform Infrared Spectroscopy, Secondary Ion Mass Spectrometry and Transmission Electron Microscopy to check material composition and structure. Materials studies show that the refractive indices of the layers can be tuned over the range from 2.5 to 3.85 (measured at 600 nm and in-plane dark conductivities over the range from 10-8 S/cm to 1 S/cm, suggesting that these doped layers are suitable for solar cell applications. The p-type layers were tested in single junction amorphous silicon p-i-n type solar cells.

  17. P-type zinc oxide spinels: application to transparent conductors and spintronics

    International Nuclear Information System (INIS)

    Stoica, Maria; S Lo, Cynthia

    2014-01-01

    We report on the electronic and optical properties of two theoretically predicted stable spinel compounds of the form ZnB 2 O 4 , where B = Ni or Cu; neither compound has been previously synthesized, so we compare them to the previously studied p-type ZnCo 2 O 4 spinel. These new materials exhibit spin polarization, which is useful for spintronics applications, and broad conductivity maxima near the valence band edge that indicate good p-type dopability. We show that 3d electrons on the octahedrally coordinated Zn atom fall deep within the valence band and do not contribute significantly to the electronic structure near the band edge of the material, while the O 2p and tetrahedrally coordinated B 3d electrons hybridize broadly in the shallow valence states, resulting in increasing curvature (i.e., decreased electron effective mass) of valence bands near the band edge. In particular, ZnCu 2 O 4 exhibits high electrical conductivities in the p-doping region near the valence band edge that, at σ=2×10 4  S cm −1 , are twice the maximum found for ZnCo 2 O 4 , a previously synthesized compound in this class of materials. This material also exhibits ferromagnetism in all of its most stable structures, which makes it a good candidate for further study as a dilute magnetic semiconductor. (paper)

  18. DFT plus U studies of Cu doping and p-type compensation in crystalline and amorphous ZnS

    NARCIS (Netherlands)

    Pham, Hieu H.; Barkema, Gerard T.|info:eu-repo/dai/nl/101275080; Wang, Lin-Wang

    2015-01-01

    Zinc sulfide is an excellent candidate for the development of a p-type transparent conducting material that has great demands in solar energy and optoelectronic applications. Doping with Cu is one potential way to make ZnS p-type while preserving its optical transparency for the solar spectrum;

  19. Low-resistance and highly transparent Ag/IZO ohmic contact to p-type GaN

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Han-Ki, E-mail: imdlhkkim@khu.ac.k [Department of Display Materials Engineering, Kyung Hee University, 1 Seochoen-dong, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of); Yi, Min-Su [Department of Materials Science and Engineering, Kyungpook National University, Sangju, Gyeongbuk, 742-711 (Korea, Republic of); Lee, Sung-Nam [Department of Engineering in Energy and Applied Chemistry, Silla University, Busan, 617-736 (Korea, Republic of)

    2009-05-29

    The electrical, structural, and optical characteristics of Ag/ZnO-doped In{sub 2}O{sub 3} (IZO) ohmic contacts to p-type GaN:Mg (2.5 x 10{sup 17} cm{sup -3}) were investigated. The Ag and IZO (10 nm/50 nm) layers were prepared by thermal evaporation and linear facing target sputtering, respectively. Although the as-deposited and 400 {sup o}C annealed samples showed rectifying behavior, the 500 and 600 {sup o}C annealed samples showed linear I-V characteristics indicative of the formation of an ohmic contact. The annealing of the contact at 600 {sup o}C for 3 min in a vacuum ({approx} 10{sup -3} Torr) resulted in the lowest specific contact resistivity of 1.8 x 10{sup -4} {Omega}.cm{sup 2} and high transparency of 78% at a wavelength of 470 nm. Using Auger electron spectroscopy, depth profiling and synchrotron X-ray scattering analysis, we suggested a possible mechanism to explain the annealing dependence of the electrical properties of the Ag/IZO contacts.

  20. Combined Scanning Nanoindentation and Tunneling Microscope Technique by Means of Semiconductive Diamond Berkovich Tip

    International Nuclear Information System (INIS)

    Lysenko, O; Novikov, N; Gontar, A; Grushko, V; Shcherbakov, A

    2007-01-01

    A combined Scanning Probe Microscope (SPM) - nanoindentation instrument enables submicron resolution indentation tests and in-situ scanning of structure surfaces. A newly developed technique is based on the scanning tunneling microscopy (STM) with integrated Berkovich diamond semiconductive tip. Diamond tips for a combined SPM were obtained using the developed procedure including the synthesis of the semiconductive borondoped diamond monocrystals by the temperature gradient method at high pressure - high temperature conditions and fabrication of the tips from these crystals considering their zonal structure. Separately grown semiconductive diamond single crystals were studied in order to find the best orientation of diamond crystals. Optimal scanning characteristics and experimental data errors were calculated by an analysis of the general functional dependence of the tunneling current from properties of the tip and specimen. Tests on the indentation and scanning of the gold film deposited on the silicon substrate employing the fabricated tips demonstrated their usability, acceptable resolution and sensitivity

  1. Semiconducting states and transport in metallic armchair-edged graphene nanoribbons

    International Nuclear Information System (INIS)

    Chen Xiongwen; Wang Haiyan; Wan Haiqing; Zhou Guanghui; Song Kehui

    2011-01-01

    Based on the nonequilibrium Green's function method within the tight-binding approximation scheme, through a scanning tunneling microscopy (STM) model, we study the low-energy electronic states and transport properties of carbon chains in armchair-edged graphene nanoribbons (AGNRs). We show that semiconducting AGNRs possess only semiconducting chains, while metallic ones possess not only metallic chains but also unconventional semiconducting chains located at the 3jth (j≠0) column from the edge (the first chain) due to the vanishing of the metallic component in the electron wavefunction. The two types of states for carbon chains in a metallic AGNR system are demonstrated by different density of states and STM tunneling currents. Moreover, a similar phenomenon is predicted in the edge region of very wide AGNRs. However, there is remarkable difference in the tunneling current between narrow and wide ribbons.

  2. Arsenic doped p-type zinc oxide films grown by radio frequency magnetron sputtering

    International Nuclear Information System (INIS)

    Fan, J. C.; Zhu, C. Y.; Fung, S.; To, C. K.; Yang, B.; Beling, C. D.; Ling, C. C.; Zhong, Y. C.; Wong, K. S.; Xie, Z.; Brauer, G.; Skorupa, W.; Anwand, W.

    2009-01-01

    As-doped ZnO films were grown by the radio frequency magnetron sputtering method. As the substrate temperature during growth was raised above ∼400 deg. C, the films changed from n type to p type. Hole concentration and mobility of ∼6x10 17 cm -3 and ∼6 cm 2 V -1 s -1 were achieved. The ZnO films were studied by secondary ion mass spectroscopy, x-ray photoelectron spectroscopy (XPS), low temperature photoluminescence (PL), and positron annihilation spectroscopy (PAS). The results were consistent with the As Zn -2V Zn shallow acceptor model proposed by Limpijumnong et al. [Phys. Rev. Lett. 92, 155504 (2004)]. The results of the XPS, PL, PAS, and thermal studies lead us to suggest a comprehensive picture of the As-related shallow acceptor formation.

  3. Highly conductive p-type amorphous oxides from low-temperature solution processing

    International Nuclear Information System (INIS)

    Li Jinwang; Tokumitsu, Eisuke; Koyano, Mikio; Mitani, Tadaoki; Shimoda, Tatsuya

    2012-01-01

    We report solution-processed, highly conductive (resistivity 1.3-3.8 mΩ cm), p-type amorphous A-B-O (A = Bi, Pb; B = Ru, Ir), processable at temperatures (down to 240 °C) that are compatible with plastic substrates. The film surfaces are smooth on the atomic scale. Bi-Ru-O was analyzed in detail. A small optical bandgap (0.2 eV) with a valence band maximum (VBM) below but very close to the Fermi level (binding energy E VBM = 0.04 eV) explains the high conductivity and suggests that they are degenerated semiconductors. The conductivity changes from three-dimensional to two-dimensional with decreasing temperature across 25 K.

  4. Hydrogen diffusion at moderate temperatures in p-type Czochralski silicon

    International Nuclear Information System (INIS)

    Huang, Y.L.; Ma, Y.; Job, R.; Ulyashin, A.G.

    2004-01-01

    In plasma-hydrogenated p-type Czochralski silicon, rapid thermal donor (TD) formation is achieved, resulting from the catalytic support of hydrogen. The n-type counter doping by TD leads to a p-n junction formation. A simple method for the indirect determination of the diffusivity of hydrogen via applying the spreading resistance probe measurements is presented. Hydrogen diffusion in silicon during both plasma hydrogenation and post-hydrogenation annealing is investigated. The impact of the hydrogenation duration, annealing temperature, and resistivity of the silicon wafers on the hydrogen diffusion is discussed. Diffusivities of hydrogen are determined in the temperature range 270-450 deg. C. The activation energy for the hydrogen diffusion is deduced to be 1.23 eV. The diffusion of hydrogen is interpreted within the framework of a trap-limited diffusion mechanism. Oxygen and hydrogen are found to be the main traps

  5. Nanoscale Cross-Point Resistive Switching Memory Comprising p-Type SnO Bilayers

    KAUST Repository

    Hota, Mrinal Kanti

    2015-02-23

    Reproducible low-voltage bipolar resistive switching is reported in bilayer structures of p-type SnO films. Specifically, a bilayer homojunction comprising SnOx (oxygen-rich) and SnOy (oxygen-deficient) in nanoscale cross-point (300 × 300 nm2) architecture with self-compliance effect is demonstrated. By using two layers of SnO film, a good memory performance is obtained as compared to the individual oxide films. The memory devices show resistance ratio of 103 between the high resistance and low resistance states, and this difference can be maintained for up to 180 cycles. The devices also show good retention characteristics, where no significant degradation is observed for more than 103 s. Different charge transport mechanisms are found in both resistance states, depending on the applied voltage range and its polarity. The resistive switching is shown to originate from the oxygen ion migration and subsequent formation/rupture of conducting filaments.

  6. Ge-intercalated graphene: The origin of the p-type to n-type transition

    KAUST Repository

    Kaloni, Thaneshwor P.

    2012-09-01

    Recently huge interest has been focussed on Ge-intercalated graphene. In order to address the effect of Ge on the electronic structure, we study Ge-intercalated free-standing C 6 and C 8 bilayer graphene, bulk C 6Ge and C 8Ge, as well as Ge-intercalated graphene on a SiC(0001) substrate, by density functional theory. In the presence of SiC(0001), there are three ways to obtain n-type graphene: i) intercalation between C layers; ii) intercalation at the interface to the substrate in combination with Ge deposition on the surface; and iii) cluster intercalation. All other configurations under study result in p-type states irrespective of the Ge coverage. We explain the origin of the different doping states and establish the conditions under which a transition occurs. © Copyright EPLA, 2012.

  7. Ultrafast carrier dynamics in a p-type GaN wafer under different carrier distributions

    Science.gov (United States)

    Fang, Yu; Yang, Junyi; Yang, Yong; Wu, Xingzhi; Xiao, Zhengguo; Zhou, Feng; Song, Yinglin

    2016-02-01

    The dependence of the carrier distribution on photoexcited carrier dynamics in a p-type Mg-doped GaN (GaN:Mg) wafer were systematically measured by femtosecond transient absorption (TA) spectroscopy. The homogeneity of the carrier distribution was modified by tuning the wavelength of the UV pulse excitation around the band gap of GaN:Mg. The TA kinetics appeared to be biexponential for all carrier distributions, and only the slower component decayed faster as the inhomogeneity of the carrier distribution increased. It was concluded that the faster component (50-70 ps) corresponded to the trap process of holes by the Mg acceptors, and the slower component (150-600 ps) corresponded to the combination of non-radiative surface recombination and intrinsic carrier recombination via dislocations. Moreover, the slower component increased gradually with the incident fluence due to the saturation of surface states.

  8. Investigation on the structural characterization of pulsed p-type porous silicon

    Science.gov (United States)

    Wahab, N. H. Abd; Rahim, A. F. Abd; Mahmood, A.; Yusof, Y.

    2017-08-01

    P-type Porous silicon (PS) was sucessfully formed by using an electrochemical pulse etching (PC) and conventional direct current (DC) etching techniques. The PS was etched in the Hydrofluoric (HF) based solution at a current density of J = 10 mA/cm2 for 30 minutes from a crystalline silicon wafer with (100) orientation. For the PC process, the current was supplied through a pulse generator with 14 ms cycle time (T) with 10 ms on time (Ton) and pause time (Toff) of 4 ms respectively. FESEM, EDX, AFM, and XRD have been used to characterize the morphological properties of the PS. FESEM images showed that pulse PS (PPC) sample produces more uniform circular structures with estimated average pore sizes of 42.14 nm compared to DC porous (PDC) sample with estimated average size of 16.37nm respectively. The EDX spectrum for both samples showed higher Si content with minimal presence of oxide.

  9. Computation On dP Type power System Stabilizer Using Fuzzy Logic

    International Nuclear Information System (INIS)

    Iskandar, M.A.; Irwan, R.; Husdi; Riza; Mardhana, E.; Triputranto, A.

    1997-01-01

    Power system stabilizers (PSS) are widely applied in power generators to damp power oscillation caused by certain disturbances in order to increase the power supply capacity. PSS design is often suffered from the difficulty on setting periodically its parameters, which are gain and compensators, in order to have an optimal damping characteristic. This paper proposes a methode to determine parameters of dP type PSS by implementing fuzzy logic rules in a computer program,to obtain the appropriate characteristics of synchronous torque and damping torque. PSS with the calculated parameters is investigated on a simulation using a non-linear electric power system of a thermal generator connected to infinite bus system model. Simulation results show that great improvement in damping characteristic and enhancement of stability margin of electric power system are obtained by using the proposed PSS

  10. A low-energy ion source for p-type doping in MBE

    International Nuclear Information System (INIS)

    Park, R.M.; Stanley, C.R.; Clampitt, R.

    1980-01-01

    A compact low-energy ion cell has been developed for use as a source of acceptor impurities for the growth of p-type semiconductor material in ultra-high vacuum by molecular beam epitaxy. A flux of either zinc or cadmium atoms is emitted under molecular effusion conditions and partially ionised in the orifice of the cell by electron bombardment. The design provides for control of both the ion energy and current at constant cell temperature. (100)InP has been grown by MBE in a flux of 1 keV Zn ions. The surface morphology and crystal structure show no degradation when compared with (100)InP grown without the Zn ions present. (author)

  11. Producing p-type conductivity in self-compensating semiconductor material

    International Nuclear Information System (INIS)

    Vechten, J.A. van; Woodall, J.M.

    1981-01-01

    This relates to compound type semiconductor materials that exhibit self-compensated n-type conductivity. The process described imparts p-type conductivity to a body of normally n-conductivity self-compensated compound semiconductor material by bombarding it with charged particles, either electrons, protons or ions. Other possible steps include introducing an acceptor impurity and applying a coating onto the crystal body. This technique will allow new semiconductor structures to be made. For example, there are some compound semiconductor materials that exhibit n-conductivity only that have energy gap widths that would permit electrical to light conversion at frequency and colours not readily achieved in semiconductor devices. (U.K.)

  12. Arsenic doped p-type zinc oxide films grown by radio frequency magnetron sputtering

    Science.gov (United States)

    Fan, J. C.; Zhu, C. Y.; Fung, S.; Zhong, Y. C.; Wong, K. S.; Xie, Z.; Brauer, G.; Anwand, W.; Skorupa, W.; To, C. K.; Yang, B.; Beling, C. D.; Ling, C. C.

    2009-10-01

    As-doped ZnO films were grown by the radio frequency magnetron sputtering method. As the substrate temperature during growth was raised above ˜400 °C, the films changed from n type to p type. Hole concentration and mobility of ˜6×1017 cm-3 and ˜6 cm2 V-1 s-1 were achieved. The ZnO films were studied by secondary ion mass spectroscopy, x-ray photoelectron spectroscopy (XPS), low temperature photoluminescence (PL), and positron annihilation spectroscopy (PAS). The results were consistent with the AsZn-2VZn shallow acceptor model proposed by Limpijumnong et al. [Phys. Rev. Lett. 92, 155504 (2004)]. The results of the XPS, PL, PAS, and thermal studies lead us to suggest a comprehensive picture of the As-related shallow acceptor formation.

  13. Determination of the refractive index of n+- and p-type porous Si samples

    International Nuclear Information System (INIS)

    Setzu, S.; Romestain, R.; Chamard, V.

    2004-01-01

    Photochemical etching of porous Si layers has been shown to be able to create micrometer or submicrometer-scale lateral gratings very promising for photonic applications. However, the reduced size of this lateral periodicity hinders standard measurements of refractive index variations. Therefore accurate characterizations of such gratings are usually difficult. In this paper we address this problem by reproducing on a larger scale (millimeter) the micrometer scale light-induced refractive index variations associated to the lateral periodicity. Using this procedure we perform standard X-ray and optical reflectivity measurements on our samples. One can then proceed to the determination of light-induced variations of porosity and refractive index. We present results for p-type samples, where the photo-dissolution can only be realized after the formation of the porous layer, as well as for n + -type samples, where light action can only be effective during the formation of the porous layer

  14. Membrane Anchoring and Ion-Entry Dynamics in P-type ATPase Copper Transport

    DEFF Research Database (Denmark)

    Grønberg, Christina; Sitsel, Oleg; Lindahl, Erik

    2016-01-01

    Cu(+)-specific P-type ATPase membrane protein transporters regulate cellular copper levels. The lack of crystal structures in Cu(+)-binding states has limited our understanding of how ion entry and binding are achieved. Here, we characterize the molecular basis of Cu(+) entry using molecular-dynamics...... simulations, structural modeling, and in vitro and in vivo functional assays. Protein structural rearrangements resulting in the exposure of positive charges to bulk solvent rather than to lipid phosphates indicate a direct molecular role of the putative docking platform in Cu(+) delivery. Mutational analyses...... and simulations in the presence and absence of Cu(+) predict that the ion-entry path involves two ion-binding sites: one transient Met148-Cys382 site and one intramembranous site formed by trigonal coordination to Cys384, Asn689, and Met717. The results reconcile earlier biochemical and x-ray absorption data...

  15. Novel method of separating macroporous arrays from p-type silicon substrate

    International Nuclear Information System (INIS)

    Peng Bobo; Wang Fei; Liu Tao; Yang Zhenya; Wang Lianwei; Fu, Ricky K. Y.; Chu, Paul K.

    2012-01-01

    This paper presents a novel method to fabricate separated macroporous silicon using a single step of photo-assisted electrochemical etching. The method is applied to fabricate silicon microchannel plates in 100 mm p-type silicon wafers, which can be used as electron multipliers and three-dimensional Li-ion microbatteries. Increasing the backside illumination intensity and decreasing the bias simultaneously can generate additional holes during the electrochemical etching which will create lateral etching at the pore tips. In this way the silicon microchannel can be separated from the substrate when the desired depth is reached, then it can be cut into the desired shape by using a laser cutting machine. Also, the mechanism of lateral etching is proposed. (semiconductor materials)

  16. Reduced thermal conductivity due to scattering centers in p-type SiGe alloys

    International Nuclear Information System (INIS)

    Beaty, J.S.; Rolfe, J.L.; Vandersande, J.; Fleurial. J.P.

    1992-01-01

    This paper reports that a theoretical model has been developed that predicts that the addition of ultra-fine, inert, phonon-scattering centers to SiGe thermoelectric material will reduce its thermal conductivity and improve its figure-of-merit. To investigate this prediction, ultra-fine particulates (20 Angstrom to 200 Angstrom) of boron nitride have been added to boron doped, p-type, 80/20 SiGe. All previous SiGe samples produced from ultra-fine SiGe powder without additions had lower thermal conductivities than standard SiGe, but high temperature (1525 K) heat treatment increased their thermal conductivity back to the value for standard SiGe. Transmission Electron Microscopy has been used to confirm the presence of occluded particulates and X-ray diffraction has been used to determine the composition to be BN

  17. PREFACE: 18th Microscopy of Semiconducting Materials Conference (MSM XVIII)

    Science.gov (United States)

    Walther, T.; Hutchison, John L.

    2013-11-01

    YRM logo This volume contains invited and contributed papers from the 18th international conference on 'Microscopy of Semiconducting Materials' held at St Catherine's College, University of Oxford, on 7-11 April 2013. The meeting was organised under the auspices of the Royal Microscopical Society and supported by the Institute of Physics as well as the Materials Research Society of the USA. This conference series deals with recent advances in semiconductor studies carried out by all forms of microscopy, with an emphasis on electron microscopy and scanning probe microscopy with high spatial resolution. This time the meeting was attended by 109 delegates from 17 countries world-wide. We were welcomed by Professor Sir Peter Hirsch, who noted that this was the first of these conferences where Professor Tony Cullis was unable to attend, owing to ill-health. During the meeting a card containing greetings from many of Tony's friends and colleagues was signed, and duly sent to Tony afterwards. As semiconductor devices shrink further new routes for device processing and characterisation need to be developed, and, for the latter, methods that offer sub-nanometre spatial resolution are particularly valuable. The various forms of imaging, diffraction and spectroscopy available in modern microscopes are powerful tools for studying the microstructure, electronic structure, chemistry and also electric fields in semiconducting materials. Recent advances in instrumentation, from lens aberration correction in both TEM and STEM instruments, to the development of a wide range of scanning probe techniques, as well as new methods of signal quantification have been presented at this conference. Two topics that have at this meeting again highlighted the interesting contributions of aberration corrected transmission electron microscopy were: contrast quantification of annular dark-field STEM images in terms of chemical composition (Z-contrast), sample thickness and strain, and the study of

  18. P-type CuxS thin films: Integration in a thin film transistor structure

    International Nuclear Information System (INIS)

    Nunes de Carvalho, C.; Parreira, P.; Lavareda, G.; Brogueira, P.; Amaral, A.

    2013-01-01

    Cu x S thin films, 80 nm thick, are deposited by vacuum thermal evaporation of sulfur-rich powder mixture, Cu 2 S:S (50:50 wt.%) with no intentional heating of the substrate. The process of deposition occurs at very low deposition rates (0.1–0.3 nm/s) to avoid the formation of Cu or S-rich films. The evolution of Cu x S films surface properties (morphology/roughness) under post deposition mild annealing in air at 270 °C and their integration in a thin film transistor (TFT) are the main objectives of this study. Accordingly, Scanning Electron Microscopy studies show Cu x S films with different surface morphologies, depending on the post deposition annealing conditions. For the shortest annealing time, the Cu x S films look to be constructed of grains with large dimension at the surface (approximately 100 nm) and consequently, irregular shape. For the longest annealing time, films with a fine-grained surface are found, with some randomly distributed large particles bound to this fine-grained surface. Atomic Force Microscopy results indicate an increase of the root-mean-square roughness of Cu x S surface with annealing time, from 13.6 up to 37.4 nm, for 255 and 345 s, respectively. The preliminary integration of Cu x S films in a TFT bottom-gate type structure allowed the study of the feasibility and compatibility of this material with the remaining stages of a TFT fabrication as well as the determination of the p-type characteristic of the Cu x S material. - Highlights: • Surface properties of annealed Cu x S films. • Variation of conductivity with annealing temperatures of Cu x S films. • Application of evaporated Cu x S films in a thin film transistor (TFT) structure. • Determination of Cu x S p-type characteristic from TFT behaviour

  19. Surface modifications caused by a swift heavy ion irradiation on crystalline p-type gallium antimonide

    Science.gov (United States)

    Jadhav, Vidya

    2015-09-01

    Surface modifications caused by a swift heavy ion irradiation on crystalline p-type gallium antimonide crystal have been reported. Single crystal, 1 0 0> orientations and ∼500 μm thick p-type GaSb samples with carrier concentration of 3.30 × 1017 cm-3 were irradiated at 100 MeV Fe7+ ions. We have used 15UD Pelletron facilities at IUAC with varying fluences of 5 × 1010-1 × 1014 ions cm-2. The effects of irradiation on these samples have been investigated using, spectroscopic ellipsometry, atomic force microscopy and ultraviolet-visible-NIR spectroscopy techniques. Ellipsometry parameters, psi (Ψ) and delta (Δ) for the unirradiated sample and samples irradiated with different fluences were recorded. The data were fit to a three phase model to determine the refractive index and extinction coefficient. The refractive index and extinction coefficient for various fluences in ultraviolet, visible, and infrared, regimes were evaluated. Atomic force microscopy has been used to study these surface modifications. In order to have more statistical information about the surface, we have plotted the height structure histogram for all the samples. For unirradiated sample, we observed the Gaussian fitting. This result indicates the more ordered height structure symmetry. Whereas for the sample irradiated with the fluence of 1 × 1013, 5 × 1013 and 1 × 1014 ions cm-2, we observed the scattered data. The width of the histogram for samples irradiated up to the fluence of 1 × 1013 ion cm-2 was found to be almost same however it decreased at higher fluence. UV reflectance spectra of the sample irradiated with increasing fluences exhibit three peaks at 292, 500 and 617 nm represent the high energy GaSb; E1, E1 + Δ and E2 band gaps in all irradiated samples.

  20. Surface modifications caused by a swift heavy ion irradiation on crystalline p-type gallium antimonide

    International Nuclear Information System (INIS)

    Jadhav, Vidya

    2015-01-01

    Surface modifications caused by a swift heavy ion irradiation on crystalline p-type gallium antimonide crystal have been reported. Single crystal, 1 0 0〉 orientations and ∼500 μm thick p-type GaSb samples with carrier concentration of 3.30 × 10 17 cm −3 were irradiated at 100 MeV Fe 7+ ions. We have used 15UD Pelletron facilities at IUAC with varying fluences of 5 × 10 10 –1 × 10 14 ions cm −2 . The effects of irradiation on these samples have been investigated using, spectroscopic ellipsometry, atomic force microscopy and ultraviolet–visible–NIR spectroscopy techniques. Ellipsometry parameters, psi (Ψ) and delta (Δ) for the unirradiated sample and samples irradiated with different fluences were recorded. The data were fit to a three phase model to determine the refractive index and extinction coefficient. The refractive index and extinction coefficient for various fluences in ultraviolet, visible, and infrared, regimes were evaluated. Atomic force microscopy has been used to study these surface modifications. In order to have more statistical information about the surface, we have plotted the height structure histogram for all the samples. For unirradiated sample, we observed the Gaussian fitting. This result indicates the more ordered height structure symmetry. Whereas for the sample irradiated with the fluence of 1 × 10 13 , 5 × 10 13 and 1 × 10 14 ions cm −2 , we observed the scattered data. The width of the histogram for samples irradiated up to the fluence of 1 × 10 13 ion cm −2 was found to be almost same however it decreased at higher fluence. UV reflectance spectra of the sample irradiated with increasing fluences exhibit three peaks at 292, 500 and 617 nm represent the high energy GaSb; E 1 , E 1 + Δ and E 2 band gaps in all irradiated samples

  1. Linear and Nonlinear Rheology Combined with Dielectric Spectroscopy of Hybrid Polymer Nanocomposites for Semiconductive Applications

    Directory of Open Access Journals (Sweden)

    Roland Kádár

    2017-01-01

    Full Text Available The linear and nonlinear oscillatory shear, extensional and combined rheology-dielectric spectroscopy of hybrid polymer nanocomposites for semiconductive applications were investigated in this study. The main focus was the influence of processing conditions on percolated poly(ethylene-butyl acrylate (EBA nanocomposite hybrids containing graphite nanoplatelets (GnP and carbon black (CB. The rheological response of the samples was interpreted in terms of dispersion properties, filler distortion from processing, filler percolation, as well as the filler orientation and distribution dynamics inside the matrix. Evidence of the influence of dispersion properties was found in linear viscoelastic dynamic frequency sweeps, while the percolation of the nanocomposites was detected in nonlinearities developed in dynamic strain sweeps. Using extensional rheology, hybrid samples with better dispersion properties lead to a more pronounced strain hardening behavior, while samples with a higher volume percentage of fillers caused a drastic reduction in strain hardening. The rheo-dielectric time-dependent response showed that in the case of nanocomposites containing only GnP, the orientation dynamics leads to non-conductive samples. However, in the case of hybrids, the orientation of the GnP could be offset by the dispersing of the CB to bridge the nanoplatelets. The results were interpreted in the framework of a dual PE-BA model, where the fillers would be concentrated mainly in the BA regions. Furthermore, better dispersed hybrids obtained using mixing screws at the expense of filler distortion via extrusion processing history were emphasized through the rheo-dielectric tests.

  2. Multicomponent semiconducting polymer systems with low crystallization-induced percolation threshold

    DEFF Research Database (Denmark)

    Goffri, S.; Müller, C.; Stingelin-Stutzmann, N.

    2006-01-01

    of the two components, during which the semiconductor is predominantly expelled to the surfaces of cast films, we can obtain vertically stratified structures in a one-step process. Incorporating these as active layers in polymer field-effect transistors, we find that the concentration of the semiconductor......–crystalline/semiconducting–insulating multicomponent systems offer expanded flexibility for realizing high-performance semiconducting architectures at drastically reduced materials cost with improved mechanical properties and environmental stability, without the need to design all performance requirements into the active semiconducting polymer...

  3. Anisotropic-Cyclicgraphene: A New Two-Dimensional Semiconducting Carbon Allotrope

    Directory of Open Access Journals (Sweden)

    Marcin Maździarz

    2018-03-01

    Full Text Available A potentially new, single-atom thick semiconducting 2D-graphene-like material, called Anisotropic-cyclicgraphene , has been generated by the two stage searching strategy linking molecular and ab initio approach. The candidate was derived from the evolutionary-based algorithm and molecular simulations was then profoundly analysed using first-principles density functional theory from the structural, mechanical, phonon, and electronic properties point of view. The proposed polymorph of graphene (rP16-P1m1 is mechanically, dynamically, and thermally stable and can achieve semiconducting with a direct band gap of 0.829 eV.

  4. Plastic Electronics and Optoelectronics: New Science and Technology from Soluble Semiconducting Polymers and Bulk Heterojunction Solar Cells Fabricated from Soluble Semiconducting Polymers

    Science.gov (United States)

    2011-11-03

    Seifter, A. J. Heeger, Adv. Mater., 23, 1679–1683 (2011). 8. Efficient, Air-Stable Bulk Heterojunction Polymer Solar Cells Using MoOx as the Anode...distribution is unlimited. 13. SUPPLEMENTARY NOTES None 14. ABSTRACT Bulk heterojunction (BHJ) solar cells were invented at UC Santa Barbara after the...Bulk Heterojunction Solar Cells Fabricated from Soluble Semiconducting Polymers Grant number: AFOSR FA9550-08-1-0248 Dr. Charle Lee, Program

  5. Band Engineering Small Bandgap p-Type Semiconductors: Investigations of their Optical and Photoelectrochemical Properties

    Science.gov (United States)

    Zoellner, Brandon

    Mixed-metal oxides containing Mn(II), Cu(I), Ta(V), Nb(V), and V(V) were investigated for their structures and properties as new p-type semiconductors and in the potential applications involving the photocatalytic conversion of water into hydrogen and oxygen. Engineering of the bandgaps was achieved by combining metal cations that have halffilled (Mn 3d5) or filled (Cu 3d10) d-orbitals together with metal cations that have empty (V/Nb/Ta 3/4/5 d0) d-orbitals. The research described herein focuses on the synthesis, optical, electronic, and photocatalytic properties of the metal-oxide semiconductors MnV2O6, Cu3VO 4, CuNb1-xTaxO3, and Cu5(Ta1-xNbx)11O30. Powder X-ray diffraction was used to probe their phase purity as well as atomic-level crystallographic details, i.e. shifts of lattice parameters, chemical compositions, and changes in local bonding environments. Optical measurements revealed visible-light bandgap sizes of ˜1.17 eV (Cu3VO4), ˜1.45 eV (MnV2O6), ˜1.89-1.97 eV (CuNb1-xTa xO3), and ˜1.97-2.50 eV (Cu5(Ta1-xNb x)11O30). The latter two were found to systematically vary as a function of composition. Electrochemical impedance spectroscopy measurements of MnV2O6 and Cu3VO 4 provided the first experimental characterization of the energetic positions of the valence and conduction bands with respect to the water oxidation and reduction potentials, as well as confirmed the p-type nature of each semiconductor. The valence and conduction band energies were found to be suitable for driving either one or both of the water-splitting half reaction (i.e. 2H+ → H2 and 2H2O → O2 + 4H+). Photoelectrochemical measurements on polycrystalline films of the Cu(I)-based semiconductors under visible-light irradiation produced cathodic currents indicative of p-type semiconductor character and chemical reduction at their surfaces in the electrolyte solution. The stability of the photocurrents was increased by the addition of CuO oxide particles either externally deposited or

  6. Thermoelectric properties of p-type sb-doped Cu2SnSe3 near room and mid temperature applications

    Science.gov (United States)

    Prasad, K. Shyam; Rao, Ashok; Chauhan, Nagendra S.; Bhardwaj, Ruchi; Vishwakarma, Avinash; Tyagi, Kriti

    2018-02-01

    In this study, we report low and mid temperature range thermoelectric properties of Sb-substituted Cu2SnSe3 compounds. The Cu2Sn1- x Sb x Se3 (0 ≤ x ≤ 0.04) alloys were prepared using conventional solid-state reaction followed by spark plasma sintering. The crystal structure was characterized using XRD and it reveals that all the samples exhibit cubic structure with space group -4/3m. The electrical transport characteristics indicate degenerate semiconducting behavior. Electrical resistivity was found to follow small polaron hopping (SPH) model in the entire temperature range of investigation. The Seebeck coefficient data reveals that the majority of charge carriers are holes and the analysis of Seebeck coefficient data gives negative values of Fermi energy indicating that the Fermi energy is below the edge of valence band. The electronic contribution ( κ e) for total thermal conductivity is found to be less than 1%. The maximum ZT value of 0.64 is observed for the sample with x = 0.03 (at 700 K) which is approximately 2.3 times that of the pristine sample.

  7. Surface modifications caused by a swift heavy ion irradiation on crystalline p-type gallium antimonide

    Energy Technology Data Exchange (ETDEWEB)

    Jadhav, Vidya, E-mail: vj1510@yahoo.com

    2015-09-01

    Surface modifications caused by a swift heavy ion irradiation on crystalline p-type gallium antimonide crystal have been reported. Single crystal, 1 0 0〉 orientations and ∼500 μm thick p-type GaSb samples with carrier concentration of 3.30 × 10{sup 17} cm{sup −3} were irradiated at 100 MeV Fe{sup 7+} ions. We have used 15UD Pelletron facilities at IUAC with varying fluences of 5 × 10{sup 10}–1 × 10{sup 14} ions cm{sup −2}. The effects of irradiation on these samples have been investigated using, spectroscopic ellipsometry, atomic force microscopy and ultraviolet–visible–NIR spectroscopy techniques. Ellipsometry parameters, psi (Ψ) and delta (Δ) for the unirradiated sample and samples irradiated with different fluences were recorded. The data were fit to a three phase model to determine the refractive index and extinction coefficient. The refractive index and extinction coefficient for various fluences in ultraviolet, visible, and infrared, regimes were evaluated. Atomic force microscopy has been used to study these surface modifications. In order to have more statistical information about the surface, we have plotted the height structure histogram for all the samples. For unirradiated sample, we observed the Gaussian fitting. This result indicates the more ordered height structure symmetry. Whereas for the sample irradiated with the fluence of 1 × 10{sup 13}, 5 × 10{sup 13} and 1 × 10{sup 14} ions cm{sup −2}, we observed the scattered data. The width of the histogram for samples irradiated up to the fluence of 1 × 10{sup 13} ion cm{sup −2} was found to be almost same however it decreased at higher fluence. UV reflectance spectra of the sample irradiated with increasing fluences exhibit three peaks at 292, 500 and 617 nm represent the high energy GaSb; E{sub 1}, E{sub 1} + Δ and E{sub 2} band gaps in all irradiated samples.

  8. Ambipolar Organic Phototransistors with p-Type/n-Type Conjugated Polymer Bulk Heterojunction Light-Sensing Layers

    KAUST Repository

    Nam, Sungho; Han, Hyemi; Seo, Jooyeok; Song, Myeonghun; Kim, Hwajeong; Anthopoulos, Thomas D.; McCulloch, Iain; Bradley, Donal D C; Kim, Youngkyoo

    2016-01-01

    Ambipolar organic phototransistors with sensing channel layers, featuring p-type and n-type conjugated polymer bulk heterojunctions, exhibit outstanding light-sensing characteristics in both p-channel and n-channel sensing operation modes.

  9. Ambipolar Organic Phototransistors with p-Type/n-Type Conjugated Polymer Bulk Heterojunction Light-Sensing Layers

    KAUST Repository

    Nam, Sungho

    2016-11-18

    Ambipolar organic phototransistors with sensing channel layers, featuring p-type and n-type conjugated polymer bulk heterojunctions, exhibit outstanding light-sensing characteristics in both p-channel and n-channel sensing operation modes.

  10. An augmented space formulation of the optical conductivity of random semiconducting alloys

    International Nuclear Information System (INIS)

    Mookerjee, A.

    1984-08-01

    A formalism has been developed for the study of optical conductivity of disordered semiconducting alloys effect of off-diagonal disorder, clustering and randomness in the electron-photon interaction matrix may be incorporated within this. The aim is to finally study GaAssub(x)Sbsub(1-x) as well as deep levels in this alloy. (author)

  11. Charge-carrier mobilities in disordered semiconducting polymers: effects of carrier density and electric field [refereed

    NARCIS (Netherlands)

    Meisel, K.D.; Pasveer, W.F.; Cottaar, J.; Tanase, C.; Coehoorn, R.; Bobbert, P.A.; Blom, P.W.M.; Leeuw, de D.M.; Michels, M.A.J.

    2006-01-01

    We model charge transport in disordered semiconducting polymers by hopping of charge carriers on a square lattice of sites with Gaussian on-site energy disorder, using Fermi-Dirac statistics. From numerically exact solns. of the Master equation, we study the dependence of the charge-carrier mobility

  12. Charge-carrier mobilities in disordered semiconducting polymers : effects of carrier density and electric field

    NARCIS (Netherlands)

    Meisel, K.D.; Pasveer, W.F.; Cottaar, J.; Tanase, C.; Coehoorn, R.; Bobbert, P.A.; Blom, P.W.M.; Leeuw, D.M. de; Michels, M.A.J.

    2006-01-01

    We model charge transport in disordered semiconducting polymers by hopping of charge carriers on a square lattice of sites with Gaussian on-site energy disorder, using Fermi-Dirac statistics. From numerically exact solutions of the Master equation, we study the dependence of the charge-carrier

  13. Field-induced detrapping in disordered organic semiconducting host-guest systems

    NARCIS (Netherlands)

    Cottaar, J.; Coehoorn, R.; Bobbert, P.A.

    2010-01-01

    In a disordered organic semiconducting host-guest material, containing a relatively small concentration of guest molecules acting as traps, the charge transport may be viewed as resulting from carriers that are detrapped from the guest to the host. Commonly used theories include only detrapping due

  14. Plasmodium P-Type Cyclin CYC3 Modulates Endomitotic Growth during Oocyst Development in Mosquitoes.

    Science.gov (United States)

    Roques, Magali; Wall, Richard J; Douglass, Alexander P; Ramaprasad, Abhinay; Ferguson, David J P; Kaindama, Mbinda L; Brusini, Lorenzo; Joshi, Nimitray; Rchiad, Zineb; Brady, Declan; Guttery, David S; Wheatley, Sally P; Yamano, Hiroyuki; Holder, Anthony A; Pain, Arnab; Wickstead, Bill; Tewari, Rita

    2015-11-01

    Cell-cycle progression and cell division in eukaryotes are governed in part by the cyclin family and their regulation of cyclin-dependent kinases (CDKs). Cyclins are very well characterised in model systems such as yeast and human cells, but surprisingly little is known about their number and role in Plasmodium, the unicellular protozoan parasite that causes malaria. Malaria parasite cell division and proliferation differs from that of many eukaryotes. During its life cycle it undergoes two types of mitosis: endomitosis in asexual stages and an extremely rapid mitotic process during male gametogenesis. Both schizogony (producing merozoites) in host liver and red blood cells, and sporogony (producing sporozoites) in the mosquito vector, are endomitotic with repeated nuclear replication, without chromosome condensation, before cell division. The role of specific cyclins during Plasmodium cell proliferation was unknown. We show here that the Plasmodium genome contains only three cyclin genes, representing an unusual repertoire of cyclin classes. Expression and reverse genetic analyses of the single Plant (P)-type cyclin, CYC3, in the rodent malaria parasite, Plasmodium berghei, revealed a cytoplasmic and nuclear location of the GFP-tagged protein throughout the lifecycle. Deletion of cyc3 resulted in defects in size, number and growth of oocysts, with abnormalities in budding and sporozoite formation. Furthermore, global transcript analysis of the cyc3-deleted and wild type parasites at gametocyte and ookinete stages identified differentially expressed genes required for signalling, invasion and oocyst development. Collectively these data suggest that cyc3 modulates oocyst endomitotic development in Plasmodium berghei.

  15. Plasmodium P-Type Cyclin CYC3 Modulates Endomitotic Growth during Oocyst Development in Mosquitoes

    KAUST Repository

    Roques, Magali; Wall, Richard J.; Douglass, Alexander P.; Ramaprasad, Abhinay; Ferguson, David J. P.; Kaindama, Mbinda L.; Brusini, Lorenzo; Joshi, Nimitray; Rchiad, ‍ Zineb; Brady, Declan; Guttery, David S.; Wheatley, Sally P.; Yamano, Hiroyuki; Holder, Anthony A.; Pain, Arnab; Wickstead, Bill; Tewari, Rita

    2015-01-01

    Cell-cycle progression and cell division in eukaryotes are governed in part by the cyclin family and their regulation of cyclin-dependent kinases (CDKs). Cyclins are very well characterised in model systems such as yeast and human cells, but surprisingly little is known about their number and role in Plasmodium, the unicellular protozoan parasite that causes malaria. Malaria parasite cell division and proliferation differs from that of many eukaryotes. During its life cycle it undergoes two types of mitosis: endomitosis in asexual stages and an extremely rapid mitotic process during male gametogenesis. Both schizogony (producing merozoites) in host liver and red blood cells, and sporogony (producing sporozoites) in the mosquito vector, are endomitotic with repeated nuclear replication, without chromosome condensation, before cell division. The role of specific cyclins during Plasmodium cell proliferation was unknown. We show here that the Plasmodium genome contains only three cyclin genes, representing an unusual repertoire of cyclin classes. Expression and reverse genetic analyses of the single Plant (P)-type cyclin, CYC3, in the rodent malaria parasite, Plasmodium berghei, revealed a cytoplasmic and nuclear location of the GFP-tagged protein throughout the lifecycle. Deletion of cyc3 resulted in defects in size, number and growth of oocysts, with abnormalities in budding and sporozoite formation. Furthermore, global transcript analysis of the cyc3-deleted and wild type parasites at gametocyte and ookinete stages identified differentially expressed genes required for signalling, invasion and oocyst development. Collectively these data suggest that cyc3 modulates oocyst endomitotic development in Plasmodium berghei.

  16. Growth of antimony doped P-type zinc oxide nanowires for optoelectronics

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhong Lin; Pradel, Ken

    2016-09-27

    In a method of growing p-type nanowires, a nanowire growth solution of zinc nitrate (Zn(NO.sub.3).sub.2), hexamethylenetetramine (HMTA) and polyethylenemine (800 M.sub.w PEI) is prepared. A dopant solution to the growth solution, the dopant solution including an equal molar ration of sodium hydroxide (NaOH), glycolic acid (C.sub.2H.sub.4O.sub.3) and antimony acetate (Sb(CH.sub.3COO).sub.3) in water is prepared. The dopant solution and the growth solution combine to generate a resulting solution that includes antimony to zinc in a ratio of between 0.2% molar to 2.0% molar, the resulting solution having a top surface. An ammonia solution is added to the resulting solution. A ZnO seed layer is applied to a substrate and the substrate is placed into the top surface of the resulting solution with the ZnO seed layer facing downwardly for a predetermined time until Sb-doped ZnO nanowires having a length of at least 5 .mu.m have grown from the ZnO seed layer.

  17. Determination of Hot-Carrier Distribution Functions in Uniaxially Stressed p-Type Germanium

    DEFF Research Database (Denmark)

    Christensen, Ove

    1973-01-01

    This paper gives a description of an experimental determination of distribution functions in k→ space of hot holes in uniaxially compressed germanium. The hot-carrier studies were made at 85°K at fields up to 1000 V/cm and uniaxial stresses up to 11 800 kg/cm2. The field and stress were always in...... probabilities with stress. A model based on the nonparabolicity of the upper p3 / 2 level is proposed for the negative differential conductivity in stressed p-type Ge....... function has been assumed. The parameters of the distribution function are then fitted to the experimental modulation. The calculation of absorption was performed numerically, using a four-band k→·p→ model. This model was checked for consistency by comparing with piezoabsorption measurements performed...... in thermal equilibrium. The average carrier energy calculated from the distribution function shows a fast increase with stress and almost saturates when the strain splitting of the two p3 / 2 levels reaches the optical-phonon energy. This saturation is interpreted in terms of the change in scattering...

  18. p-type doping by platinum diffusion in low phosphorus doped silicon

    Science.gov (United States)

    Ventura, L.; Pichaud, B.; Vervisch, W.; Lanois, F.

    2003-07-01

    In this work we show that the cooling rate following a platinum diffusion strongly influences the electrical conductivity in weakly phosphorus doped silicon. Diffusions were performed at the temperature of 910 °C in the range of 8 32 hours in 0.6, 30, and 60 Ωrm cm phosphorus doped silicon samples. Spreading resistance profile analyses clearly show an n-type to p-type conversion under the surface when samples are cooled slowly. On the other hand, a compensation of the phosphorus donors can only be observed when samples are quenched. One Pt related acceptor deep level at 0.43 eV from the valence band is assumed to be at the origin of the type conversion mechanism. Its concentration increases by lowering the applied cooling rate. A complex formation with fast species such as interstitial Pt atoms or intrinsic point defects is expected. In 0.6 Ωrm cm phosphorus doped silicon, no acceptor deep level in the lower band gap is detected by DLTS measurement. This removes the opportunity of a pairing between phosphorus and platinum and suggests the possibility of a Fermi level controlled complex formation.

  19. Beryllium doped p-type GaN grown by metal-organic chemical vapor depostion

    International Nuclear Information System (INIS)

    Al-Tahtamouni, T.M.; Sedhain, A.; Lin, J.Y.; Jiang, H.X.

    2010-01-01

    The authors report on the growth of Be-doped p-type GaN epilayers by metal-organic chmical vapor deposition (MOCVD). The electrical and optical properties of the Be-doped GaN epilayers were studied by Hall-effect measurements and photoluminescence (PL) spectroscopy. The PL spectra of Be-doped GaN epilayers ethibited two emission lines at 3.36 and 2.71 eV, which were obsent in undoped epilayers. The transition at 3.36 eV was at 3.36 and 2.71eV, which were absent in undoped epilayers. The transition at 3.36 eV was assigned to the transition of free electrons to the neutral Be acceptor Be d eg.. The transition at 2.71 eV was assigned to the transition of electrons bound to deep level donors to the Be d eg. acceptors. Three independent measurements: (a) resistivity vs. temperature, (b) PL peak positions between Be doped and undoped GaN and (c) activation energy of 2.71 eV transition all indicate that the Be energy level is between 120 and 140 meV above the valence band. This is about 20-40 meV shallower than the Mg energy level (160 meV) in GaN. It is thus concluded that Be could be an excellent acceptor dopant in nitride materials. (authors).

  20. Site preference of Mg acceptors and improvement of p-type doping efficiency in nitride alloys.

    Science.gov (United States)

    Park, Ji-Sang; Chang, K J

    2013-06-19

    We perform first-principles density functional calculations to investigate the effect of Al and In on the formation energy and acceptor level of Mg in group-III nitride alloys. Our calculations reveal a tendency for the Mg dopants to prefer to occupy the lattice sites surrounded with Al atoms, whereas hole carriers are generated in In- or Ga-rich sites. The separation of the Mg dopants and hole carriers is energetically more favourable than a random distribution of dopants, being attributed to the local bonding effect of weak In and strong Al potentials in alloys. As a consequence, the Mg acceptor level, which represents the activation energy of Mg, tends to decrease with increasing numbers of Al next-nearest neighbours, whereas it increases as the number of In next-nearest neighbours increases. Based on the results, we suggest that the incorporation of higher Al and lower In compositions will improve the p-type doping efficiency in quaternary alloys, in comparison with GaN or AlGaN ternary alloys with similar band gaps.

  1. Porous silicon damage enhanced phosphorus and aluminium gettering of p-type Czochralski silicon

    International Nuclear Information System (INIS)

    Hassen, M.; Ben Jaballah, A.; Hajji, M.; Rahmouni, H.; Selmi, A.; Ezzaouia, H.

    2005-01-01

    In this work, porous silicon damage (PSD) is presented as a simple sequence for efficient external purification techniques. The method consists of using thin nanoporous p-type silicon on both sides of the silicon substrates with randomly hemispherical voids. Then, two main sample types are processed. In the first type, thin aluminium layers (≥1 μm) are thermally evaporated followed by photo-thermal annealing treatments in N 2 atmosphere at one of several temperatures ranging between 600 and 800 deg. C. In the second type, phosphorus is continually diffused in N 2 /O 2 ambient in a solid phase from POCl 3 solution during heating at one of several temperatures ranging between 750 and 1000 deg. C for 1 h. Hall Effect and Van Der Pauw methods prove the existence of an optimum temperature in the case of phosphorus gettering at 900 deg. C yielding a Hall mobility of about 982 cm 2 V -1 s -1 . However, in the case of aluminium gettering, there is no gettering limit in the as mentioned temperature range. Metal/Si Schottky diodes are elaborated to clarify these improvements. In this study, we demonstrate that enhanced metal solubility model cannot explain the gettering effect. The solid solubility of aluminium is higher than that of P atoms in silicon; however, the device yield confirms the effectiveness of phosphorus as compared to aluminium

  2. A Proposed Method for Improving the Performance of P-Type GaAs IMPATTs

    Directory of Open Access Journals (Sweden)

    H. A. El-Motaafy

    2012-07-01

    Full Text Available A special waveform is proposed and assumed to be the optimum waveform for p-type GaAs IMPATTs. This waveform is deduced after careful and extensive study of the performance of these devices. The results presented here indicate the superiority of the performance of the IMPATTs driven by the proposed waveform over that obtained when the same IMPATTs are driven by the conventional sinusoidal waveform. These results are obtained using a full-scale computer simulation program that takes fully into account all the physical effects pertinent to IMPATT operation.  In this paper, it is indicated that the superiority of the proposed waveform is attributed to its ability to reduce the bad effects that usually degrade the IMPATT performance such as the space-charge effect and the drift-velocity dropping below saturation effect. The superiority is also attributed to the ability of the proposed waveform to improve the phase relationship between the terminal voltage and the induced current.Key Words: Computer-Aided Design, GaAs IMPATT, Microwave Engineering

  3. P-TYPE PLANET–PLANET SCATTERING: KEPLER CLOSE BINARY CONFIGURATIONS

    International Nuclear Information System (INIS)

    Gong, Yan-Xiang

    2017-01-01

    A hydrodynamical simulation shows that a circumbinary planet will migrate inward to the edge of the disk cavity. If multiple planets form in a circumbinary disk, successive migration will lead to planet–planet scattering (PPS). PPS of Kepler -like circumbinary planets is discussed in this paper. The aim of this paper is to answer how PPS affects the formation of these planets. We find that a close binary has a significant influence on the scattering process. If PPS occurs near the unstable boundary of a binary, about 10% of the systems can be completely destroyed after PPS. In more than 90% of the systems, there is only one planet left. Unlike the eccentricity distribution produced by PPS in a single star system, the surviving planets generally have low eccentricities if PPS take place near the location of the currently found circumbinary planets. In addition, the ejected planets are generally the innermost of two initial planets. The above results depend on the initial positions of the two planets. If the initial positions of the planets are moved away from the binary, the evolution tends toward statistics similar to those around single stars. In this process, the competition between the planet–planet force and the planet-binary force makes the eccentricity distribution of surviving planets diverse. These new features of P-type PPS will deepen our understanding of the formation of these circumbinary planets.

  4. Experimental verification of temperature coefficients of resistance for uniformly doped P-type resistors in SOI

    Science.gov (United States)

    Olszacki, M.; Maj, C.; Bahri, M. Al; Marrot, J.-C.; Boukabache, A.; Pons, P.; Napieralski, A.

    2010-06-01

    Many today's microsystems like strain-gauge-based piezoresistive pressure sensors contain doped resistors. If one wants to predict correctly the temperature impact on the performance of such devices, the accurate data about the temperature coefficients of resistance (TCR) are essential. Although such data may be calculated using one of the existing mobility models, our experiments showed that we can observe the huge mismatch between the calculated and measured values. Thus, in order to investigate the TCR values, a set of the test structures that contained doped P-type resistors was fabricated. As the TCR value also depends on the doping profile shape, we decided to use the very thin, 340 nm thick SOI wafers in order to fabricate the quasi-uniformly doped silicon layers ranging from 2 × 1017 at cm-3 to 1.6 × 1019 at cm-3. The results showed that the experimental data for the first-order TCR are quite far from the calculated ones especially over the doping range of 1018-1019 at cm-3 and quite close to the experimental ones obtained by Bullis about 50 years ago for bulk silicon. Moreover, for the first time, second-order coefficients that were not very consistent with the calculations were obtained.

  5. TSC measurements on proton-irradiated p-type Si-sensors

    Energy Technology Data Exchange (ETDEWEB)

    Donegani, Elena; Fretwurst, Eckhart; Garutti, Erika; Junkes, Alexandra [University of Hamburg (Germany)

    2016-07-01

    Thin n{sup +}p Si sensors are potential candidates for coping with neutron equivalent fluences up to 2.10{sup 16} n{sub eq}/cm{sup 2} and an ionizing dose in the order of a few MGy, which are expected e.g. for the HL-LHC upgrade. The aim of the present work is to provide experimental data on radiation-induced defects in order to: firstly, get a deeper understanding of the properties of hadron induced defects, and secondly develop a radiation damage model based on microscopic measurements. Therefore, the outcomes of Thermally Stimulated Current measurements on 200 μm thick Float-Zone (FZ) and Magnetic Czochralski (MCz) diodes will be shown, as a results of irradiation with 23 MeV protons and isothermal annealing. The samples were irradiated in the fluence range (0.3-1).10{sup 14} n{sub eq}/cm{sup 2}, so that the maximal temperature at which the TSC signal is still sharply distinguishable from the dark current is 200 K. In particular, special focus will be given to the defect introduction rate and to the issue of boron removal in p-type silicon. Annealing studies allow to distinguish which defects mainly contribute to the leakage current and which to the space charge, and thus correlate microscopic defects properties with macroscopic sensor properties.

  6. Orientation Effects in Ballistic High-Strained P-type Si Nanowire FETs

    Directory of Open Access Journals (Sweden)

    Hong Yu

    2009-04-01

    Full Text Available In order to design and optimize high-sensitivity silicon nanowire-field-effect transistor (SiNW FET pressure sensors, this paper investigates the effects of channel orientations and the uniaxial stress on the ballistic hole transport properties of a strongly quantized SiNW FET placed near the high stress regions of the pressure sensors. A discrete stress-dependent six-band k.p method is used for subband structure calculation, coupled to a two-dimensional Poisson solver for electrostatics. A semi-classical ballistic FET model is then used to evaluate the ballistic current-voltage characteristics of SiNW FETs with and without strain. Our results presented here indicate that [110] is the optimum orientation for the p-type SiNW FETs and sensors. For the ultra-scaled 2.2 nm square SiNW, due to the limit of strong quantum confinement, the effect of the uniaxial stress on the magnitude of ballistic drive current is too small to be considered, except for the [100] orientation. However, for larger 5 nm square SiNW transistors with various transport orientations, the uniaxial tensile stress obviously alters the ballistic performance, while the uniaxial compressive stress slightly changes the ballistic hole current. Furthermore, the competition of injection velocity and carrier density related to the effective hole masses is found to play a critical role in determining the performance of the nanotransistors.

  7. Properties of p-type amorphous silicon carbide window layers prepared using boron trifluoride

    Energy Technology Data Exchange (ETDEWEB)

    Gandia, J J [Inst. de Energias Renovables, CIEMAT, Madrid (Spain); Gutierrez, M T [Inst. de Energias Renovables, CIEMAT, Madrid (Spain); Carabe, J [Inst. de Energias Renovables, CIEMAT, Madrid (Spain)

    1993-03-01

    One set (A) of undoped and three sets (B, C and D) of doped hydrogenated amorphous silicon carbide samples have been made in the framework of a research plan for obtaining high quality p-type window layers by radiofrequency glow discharge of silane-based gas mixtures. The samples of sets A and B were made using different RF-power-density to mass-flow ratios for various methane percentages in the gas mixture. The best carbon incorporation in the amorphous silicon lattice was obtained at the highest RF-power density. The properties of sets C and D, prepared using different RF-power densities and silane and methane proportions have been analysed as functions of the concentration of boron trifluoride with respect to silane. In both cases, the optical gap E[sub G], after a slight initial decrease, remains at a value of approximately 2.1 eV without quenching in the doping ranges covered. The best conductivity obtained is 2x10[sup -7] ([Omega] cm)[sup -1]. IR spectra allow to associate these features with the structural quality of the films. (orig.)

  8. Technology development of p-type microstrip detectors with radiation hard p-spray isolation

    International Nuclear Information System (INIS)

    Pellegrini, G.; Fleta, C.; Campabadal, F.; Diez, S.; Lozano, M.; Rafi, J.M.; Ullan, M.

    2006-01-01

    A technology for the fabrication of p-type microstrip silicon radiation detectors using p-spray implant isolation has been developed at CNM-IMB. The p-spray isolation has been optimized in order to withstand a gamma irradiation dose up to 50 Mrad (Si), which represents the ionization radiation dose expected in the middle region of the SCT-Atlas detector of the future Super-LHC during 10 years of operation. The best technological options for the p-spray implant were found by using a simulation software package and dedicated calibration runs. Using the optimized technology, detectors have been fabricated in the Clean Room facility of CNM-IMB, and characterized by reverse current and capacitance measurements before and after irradiation. The average full depletion voltage measured on the non-irradiated detectors was V FD =41±3 V, while the leakage current density for the microstrip devices at V FD +20 V was 400 nA/cm 2

  9. Plasmodium P-Type Cyclin CYC3 Modulates Endomitotic Growth during Oocyst Development in Mosquitoes

    KAUST Repository

    Roques, Magali

    2015-11-13

    Cell-cycle progression and cell division in eukaryotes are governed in part by the cyclin family and their regulation of cyclin-dependent kinases (CDKs). Cyclins are very well characterised in model systems such as yeast and human cells, but surprisingly little is known about their number and role in Plasmodium, the unicellular protozoan parasite that causes malaria. Malaria parasite cell division and proliferation differs from that of many eukaryotes. During its life cycle it undergoes two types of mitosis: endomitosis in asexual stages and an extremely rapid mitotic process during male gametogenesis. Both schizogony (producing merozoites) in host liver and red blood cells, and sporogony (producing sporozoites) in the mosquito vector, are endomitotic with repeated nuclear replication, without chromosome condensation, before cell division. The role of specific cyclins during Plasmodium cell proliferation was unknown. We show here that the Plasmodium genome contains only three cyclin genes, representing an unusual repertoire of cyclin classes. Expression and reverse genetic analyses of the single Plant (P)-type cyclin, CYC3, in the rodent malaria parasite, Plasmodium berghei, revealed a cytoplasmic and nuclear location of the GFP-tagged protein throughout the lifecycle. Deletion of cyc3 resulted in defects in size, number and growth of oocysts, with abnormalities in budding and sporozoite formation. Furthermore, global transcript analysis of the cyc3-deleted and wild type parasites at gametocyte and ookinete stages identified differentially expressed genes required for signalling, invasion and oocyst development. Collectively these data suggest that cyc3 modulates oocyst endomitotic development in Plasmodium berghei.

  10. Reinventing a p-type doping process for stable ZnO light emitting devices

    Science.gov (United States)

    Xie, Xiuhua; Li, Binghui; Zhang, Zhenzhong; Shen, Dezhen

    2018-06-01

    A tough challenge for zinc oxide (ZnO) as the ultraviolet optoelectronics materials is realizing the stable and reliable p-type conductivity. Self-compensation, coming from native donor-type point defects, is a big obstacle. In this work, we introduce a dynamic N doping process with molecular beam epitaxy, which is accomplished by a Zn, N-shutter periodic switch (a certain time shift between them for independent optimization of surface conditions). During the epitaxy, N adatoms are incorporated under the condition of (2  ×  2)  +  Zn vacancies reconstruction on a Zn-polar surface, at which oxygen vacancies (V O), the dominating compensating donors, are suppressed. With the p-ZnO with sufficient holes surviving, N concentration ~1  ×  1019 cm‑3, is employed in a p-i-n light emitting devices. Significant ultraviolet emission of electroluminescence spectra without broad green band (related to V O) at room-temperature are demonstrated. The devices work incessantly without intentional cooling for over 300 h at a luminous intensity reduction of one order of magnitude under the driving of a 10 mA continuous current, which are the demonstration for p-ZnO stability and reliability.

  11. Experimental verification of temperature coefficients of resistance for uniformly doped P-type resistors in SOI

    International Nuclear Information System (INIS)

    Olszacki, M; Maj, C; Al Bahri, M; Marrot, J-C; Boukabache, A; Pons, P; Napieralski, A

    2010-01-01

    Many today's microsystems like strain-gauge-based piezoresistive pressure sensors contain doped resistors. If one wants to predict correctly the temperature impact on the performance of such devices, the accurate data about the temperature coefficients of resistance (TCR) are essential. Although such data may be calculated using one of the existing mobility models, our experiments showed that we can observe the huge mismatch between the calculated and measured values. Thus, in order to investigate the TCR values, a set of the test structures that contained doped P-type resistors was fabricated. As the TCR value also depends on the doping profile shape, we decided to use the very thin, 340 nm thick SOI wafers in order to fabricate the quasi-uniformly doped silicon layers ranging from 2 × 10 17 at cm −3 to 1.6 × 10 19 at cm −3 . The results showed that the experimental data for the first-order TCR are quite far from the calculated ones especially over the doping range of 10 18 –10 19 at cm −3 and quite close to the experimental ones obtained by Bullis about 50 years ago for bulk silicon. Moreover, for the first time, second-order coefficients that were not very consistent with the calculations were obtained.

  12. Defect study of Zn-doped p-type gallium antimonide using positron lifetime spectroscopy

    International Nuclear Information System (INIS)

    Ling, C. C.; Fung, S.; Beling, C. D.; Huimin, Weng

    2001-01-01

    Defects in p-type Zn-doped liquid-encapsulated Czochralski--grown GaSb were studied by the positron lifetime technique. The lifetime measurements were performed on the as-grown sample at temperature varying from 15 K to 297 K. A positron trapping center having a characteristic lifetime of 317 ps was identified as the neutral V Ga -related defect. Its concentration in the as-grown sample was found to be in the range of 10 17 --10 18 cm -3 . At an annealing temperature of 300 o C, the V Ga -related defect began annealing out and a new defect capable of trapping positrons was formed. This newly formed defect, having a lifetime value of 379 ps, is attributed to a vacancy--Zn-defect complex. This defect started annealing out at a temperature of 580 o C. A positron shallow trap having binding energy and concentration of 75 meV and 10 18 cm -3 , respectively, was also observed in the as-grown sample. This shallow trap is attributed to positrons forming hydrogenlike Rydberg states with the ionized dopant acceptor Zn

  13. Inkjet-printed p-type nickel oxide thin-film transistor

    Science.gov (United States)

    Hu, Hailong; Zhu, Jingguang; Chen, Maosheng; Guo, Tailiang; Li, Fushan

    2018-05-01

    High-performance inkjet-printed nickel oxide thin-film transistors (TFTs) with Al2O3 high-k dielectric have been fabricated using a sol-gel precursor ink. The "coffee ring" effect during the printing process was facilely restrained by modifying the viscosity of the ink to control the outward capillary flow. The impacts on the device performance was studied in detail in consideration of annealing temperature of the nickel oxide film and the properties of dielectric layer. The optimized switching ability of the device were achieved at an annealing temperature of 280 °C on a 50-nm-thick Al2O3 dielectric layer, with a hole mobility of 0.78 cm2/V·s, threshold voltage of -0.6 V and on/off current ratio of 5.3 × 104. The as-printed p-type oxide TFTs show potential application in low-cost, large-area complementary electronic devices.

  14. Experimental study of the organic light emitting diode with a p-type silicon anode

    International Nuclear Information System (INIS)

    Ma, G.L.; Xu, A.G.; Ran, G.Z.; Qiao, Y.P.; Zhang, B.R.; Chen, W.X.; Dai, L.; Qin, G.G.

    2006-01-01

    We have fabricated and studied an organic light emitting diode (OLED) with a p-type silicon anode and a SiO 2 buffer layer between the anode and the organic layers which emits light from a semitransparent top Yb/Au cathode. The luminance of the OLED is up to 5600 cd/m 2 at 17 V and 1800 mA/cm 2 , the current efficiency is 0.31 cd/A. Both its luminance and current efficiency are much higher than those of the OLEDs with silicon as the anodes reported previously. The enhancement of the luminance and efficiency can be attributed to an improved balance between the hole- and electron-injection through two efficient ways: 1) restraining the hole-injection by inserting an ultra-thin SiO 2 buffer layer between the Si anode and the organic layers; and 2) enhancing the electron-injection by using a low work function, low optical reflectance and absorption semitransparent Yb/Au cathode

  15. Electrical transport properties of manganese containing pyrochlore type semiconducting oxides using impedance analyses

    International Nuclear Information System (INIS)

    Sumi, S.; Prabhakar Rao, P.; Mahesh, S.K.; Koshy, Peter

    2012-01-01

    Graphical abstract: DC conductivity variation of CaCe 1−x Mn x SnNbO 7−δ (x = 0, 0.2, 0.4 and 0.6) with inverse of temperature. Variation of conductivity with Mn concentration at 600 °C is shown in the inset. Display Omitted Highlights: ► We have observed that the structural ordering as well as grain size increase with Mn substitution. ► Impedance analysis proved that a correlated barrier hopping type conduction mechanism is involved in the materials. ► Activation energy as well as electrical conductivity increases with increase in Mn substitution. ► Localization of electrons associated with Mn 2+ and structural ordering are the key factors for the increased activation energy with Mn substitution. ► All the materials showed good NTC thermistor properties. -- Abstract: A new series of manganese containing pyrochlore type semiconducting oxides CaCe 1−x Mn x SnNbO 7−δ (x = 0, 0.2, 0.4 and 0.6) have been synthesized to study the effect of Mn substitution on the structure, microstructure and electrical properties of these samples. X-ray diffraction and scanning electron microscopy studies revealed an increase of structural ordering and grain size respectively with increase of Mn substitution. Rietveld analysis and Raman spectroscopy were also employed to corroborate the XRD results. The bulk resistance measurements with temperature exhibit negative temperature coefficient behavior. The impedance analysis of the samples revealed a non-Debye type relaxation existed in the materials. The ac conductivity variation with temperature and frequency indicates a correlated barrier hopping type conduction mechanism in these materials. The barrier height and the intersite separation for hopping influence the electrical conductivity of these samples and are found to be a function of localization of electrons associated with the Mn 2+ ions and the unit cell volume respectively. The Mn substitution increases both electrical conductivity and activation energy

  16. Plasmodium P-Type Cyclin CYC3 Modulates Endomitotic Growth during Oocyst Development in Mosquitoes

    Science.gov (United States)

    Ferguson, David J. P.; Kaindama, Mbinda L.; Brusini, Lorenzo; Joshi, Nimitray; Rchiad, Zineb; Brady, Declan; Guttery, David S.; Wheatley, Sally P.; Yamano, Hiroyuki; Holder, Anthony A.; Pain, Arnab; Wickstead, Bill; Tewari, Rita

    2015-01-01

    Cell-cycle progression and cell division in eukaryotes are governed in part by the cyclin family and their regulation of cyclin-dependent kinases (CDKs). Cyclins are very well characterised in model systems such as yeast and human cells, but surprisingly little is known about their number and role in Plasmodium, the unicellular protozoan parasite that causes malaria. Malaria parasite cell division and proliferation differs from that of many eukaryotes. During its life cycle it undergoes two types of mitosis: endomitosis in asexual stages and an extremely rapid mitotic process during male gametogenesis. Both schizogony (producing merozoites) in host liver and red blood cells, and sporogony (producing sporozoites) in the mosquito vector, are endomitotic with repeated nuclear replication, without chromosome condensation, before cell division. The role of specific cyclins during Plasmodium cell proliferation was unknown. We show here that the Plasmodium genome contains only three cyclin genes, representing an unusual repertoire of cyclin classes. Expression and reverse genetic analyses of the single Plant (P)-type cyclin, CYC3, in the rodent malaria parasite, Plasmodium berghei, revealed a cytoplasmic and nuclear location of the GFP-tagged protein throughout the lifecycle. Deletion of cyc3 resulted in defects in size, number and growth of oocysts, with abnormalities in budding and sporozoite formation. Furthermore, global transcript analysis of the cyc3-deleted and wild type parasites at gametocyte and ookinete stages identified differentially expressed genes required for signalling, invasion and oocyst development. Collectively these data suggest that cyc3 modulates oocyst endomitotic development in Plasmodium berghei. PMID:26565797

  17. Fabrication and simulation of single crystal p-type Si nanowire using SOI technology

    International Nuclear Information System (INIS)

    Dehzangi, Arash; Larki, Farhad; Naseri, Mahmud G.; Navasery, Manizheh; Majlis, Burhanuddin Y.; Razip Wee, Mohd F.; Halimah, M.K.; Islam, Md. Shabiul; Md Ali, Sawal H.; Saion, Elias

    2015-01-01

    Highlights: • Single crystal silicon nanowire is fabricated on Si on insulator substrate, using atomic force microscope (AFM) nanolithography and KOH + IPA chemical wet etching. • Some of major parameters in fabrication process, such as writing speed and applied voltage along with KOH etching depth are investigated, and then the I–V characteristic of Si nanowires is measured. • For better understanding of the charge transmission through the nanowire, 3D-TCAD simulation is performed to simulate the Si nanowires with the same size of the fabricated ones, and variation of majority and minority carriers, hole quasi-Fermi level and generation/recombination rate are investigated. - Abstract: Si nanowires (SiNWs) as building blocks for nanostructured materials and nanoelectronics have attracted much attention due to their major role in device fabrication. In the present work a top-down fabrication approach as atomic force microscope (AFM) nanolithography was performed on Si on insulator (SOI) substrate to fabricate a single crystal p-type SiNW. To draw oxide patterns on top of the SOI substrate local anodic oxidation was carried out by AFM in contact mode. After the oxidation procedure, an optimized solution of 30 wt.% KOH with 10 vol.% IPA for wet etching at 63 °C was applied to extract the nanostructure. The fabricated SiNW had 70–85 nm full width at half maximum width, 90 nm thickness and 4 μm length. The SiNW was simulated using Sentaurus 3D software with the exact same size of the fabricated device. I–V characterization of the SiNW was measured and compared with simulation results. Using simulation results variation of carrier's concentrations, valence band edge energy and recombination generation rate for different applied voltage were investigated

  18. Fabrication and simulation of single crystal p-type Si nanowire using SOI technology

    Energy Technology Data Exchange (ETDEWEB)

    Dehzangi, Arash, E-mail: arashd53@hotmail.com [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Larki, Farhad [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Naseri, Mahmud G. [Department of Physics, Faculty of Science, Malayer University, Malayer, Hamedan (Iran, Islamic Republic of); Navasery, Manizheh [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Majlis, Burhanuddin Y.; Razip Wee, Mohd F. [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Halimah, M.K. [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Islam, Md. Shabiul; Md Ali, Sawal H. [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Saion, Elias [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2015-04-15

    Highlights: • Single crystal silicon nanowire is fabricated on Si on insulator substrate, using atomic force microscope (AFM) nanolithography and KOH + IPA chemical wet etching. • Some of major parameters in fabrication process, such as writing speed and applied voltage along with KOH etching depth are investigated, and then the I–V characteristic of Si nanowires is measured. • For better understanding of the charge transmission through the nanowire, 3D-TCAD simulation is performed to simulate the Si nanowires with the same size of the fabricated ones, and variation of majority and minority carriers, hole quasi-Fermi level and generation/recombination rate are investigated. - Abstract: Si nanowires (SiNWs) as building blocks for nanostructured materials and nanoelectronics have attracted much attention due to their major role in device fabrication. In the present work a top-down fabrication approach as atomic force microscope (AFM) nanolithography was performed on Si on insulator (SOI) substrate to fabricate a single crystal p-type SiNW. To draw oxide patterns on top of the SOI substrate local anodic oxidation was carried out by AFM in contact mode. After the oxidation procedure, an optimized solution of 30 wt.% KOH with 10 vol.% IPA for wet etching at 63 °C was applied to extract the nanostructure. The fabricated SiNW had 70–85 nm full width at half maximum width, 90 nm thickness and 4 μm length. The SiNW was simulated using Sentaurus 3D software with the exact same size of the fabricated device. I–V characterization of the SiNW was measured and compared with simulation results. Using simulation results variation of carrier's concentrations, valence band edge energy and recombination generation rate for different applied voltage were investigated.

  19. Field-induced surface passivation of p-type silicon by using AlON films

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, S.N.; Parm, I.O.; Dhungel, S.K.; Jang, K.S.; Jeong, S.W.; Yoo, J.; Hwang, S.H.; Yi, J. [School of Information and Communication Engineering, Sungkyunkwan University, 300 Chunchun dong, Jangan-gu, Suwon-440746 (Korea)

    2008-02-15

    In the present work, we report on the evidence for a high negative charge density in aluminum oxynitride (AlON) coating on silicon. A comparative study was carried out on the composition and electrical properties of AlON and aluminum nitride (AlN). AlON films were deposited on p-type Si (1 0 0) substrate by RF magnetron sputtering using a mixture of argon and oxygen gases at substrate temperature of 300 C. The electrical properties of the AlON, AlN films were studied through capacitance-voltage (C-V) characteristics of metal-insulator-semiconductor (MIS) using the films as insulating layers. The flatband voltage shift V{sub FB} observed for AlON is around 4.5 V, which is high as compared to the AlN thin film. Heat treatment caused the V{sub FB} reduction to 3 V, but still the negative charge density was observed to be very high. In the AlN film, no fixed negative charge was observed at all. The XRD spectrum of AlON shows the major peaks of AlON (2 2 0) and AlN (0 0 2), located at 2{theta} value of 32.96 and 37.8 , respectively. The atomic percentage of Al, N in AlN film was found to be 42.5% and 57.5%, respectively. Atomic percentages of Al, N and O in EDS of AlON film are 20.21%, 27.31% and 52.48%, respectively. (author)

  20. Host and Pathogen Copper-Transporting P-Type ATPases Function Antagonistically during Salmonella Infection.

    Science.gov (United States)

    Ladomersky, Erik; Khan, Aslam; Shanbhag, Vinit; Cavet, Jennifer S; Chan, Jefferson; Weisman, Gary A; Petris, Michael J

    2017-09-01

    Copper is an essential yet potentially toxic trace element that is required by all aerobic organisms. A key regulator of copper homeostasis in mammalian cells is the copper-transporting P-type ATPase ATP7A, which mediates copper transport from the cytoplasm into the secretory pathway, as well as copper export across the plasma membrane. Previous studies have shown that ATP7A-dependent copper transport is required for killing phagocytosed Escherichia coli in a cultured macrophage cell line. In this investigation, we expanded on these studies by generating Atp7a LysMcre mice, in which the Atp7a gene was specifically deleted in cells of the myeloid lineage, including macrophages. Primary macrophages isolated from Atp7a LysMcre mice exhibit decreased copper transport into phagosomal compartments and a reduced ability to kill Salmonella enterica serovar Typhimurium compared to that of macrophages isolated from wild-type mice. The Atp7a LysMcre mice were also more susceptible to systemic infection by S Typhimurium than wild-type mice. Deletion of the S Typhimurium copper exporters, CopA and GolT, was found to decrease infection in wild-type mice but not in the Atp7a LysMcre mice. These studies suggest that ATP7A-dependent copper transport into the phagosome mediates host defense against S Typhimurium, which is counteracted by copper export from the bacteria via CopA and GolT. These findings reveal unique and opposing functions for copper transporters of the host and pathogen during infection. Copyright © 2017 American Society for Microbiology.

  1. Inkjet Printing NiO-Based p-Type Dye-Sensitized Solar Cells.

    Science.gov (United States)

    Brisse, R; Faddoul, R; Bourgeteau, T; Tondelier, D; Leroy, J; Campidelli, S; Berthelot, T; Geffroy, B; Jousselme, B

    2017-01-25

    Fabrication at low cost of transparent p-type semiconductors with suitable electronic properties is essential toward the scalability of many electronic devices, especially for photovoltaic and photocatalytic applications. In this context, the synthesis of mesoporous NiO films through inkjet printing of a sol-gel ink was investigated for the first time. Nickel chloride and Pluronic F-127, used as nickel oxide precursor and pore-forming agent, respectively, were formulated in a water/ethanol mixture to prepare a jettable ink for Dimatix printer. Multilayer NiO films were formed, and different morphologies could be obtained by playing on the interlayer thermal treatment. At low temperature (30 °C), a porous nanoparticulate-nanofiber dual-pore structure was observed. On the other hand, with a high temperature treatment (450 °C), nanoparticulate denser films without any dual structure were obtained. The mechanism for NiO formation during the final sintering step, investigated by means of X-ray photolectron spectroscopy, shows that a Ni(OH) 2 species is an intermediate between NiCl 2 and NiO. The different morphologies and thicknesses of the NiO films were correlated to their performance in a p-DSSC configuration, using a new push-pull dye (so-called "RBG-174") and an iodine-based electrolyte. Moreover, the positive impact of a nanometric NiO x layer deposited by spin-coating and introduced between FTO and the NiO mesoporous network is highlighted in the present work. The best results were obtained with NiO x /four layer-NiO mesoporous photocathodes of 860 nm, with a current density at the short circuit of 3.42 mA cm -2 (irradiance of 100 mW cm -2 spectroscopically distributed following AM 1.5).

  2. P-type thin films transistors with solution-deposited lead sulfide films as semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Carrillo-Castillo, A.; Salas-Villasenor, A.; Mejia, I. [Department of Materials Science and Engineering, The University of Texas at Dallas. 800 West Campbell Rd, Richardson, TX 75083 (United States); Aguirre-Tostado, S. [Centro de Investigacion en Materiales Avanzados, S. C. Alianza Norte 202, Parque de Investigacion e Innovacion Tecnologica, Apodaca, Nuevo Leon, C.P. 666000 (Mexico); Gnade, B.E. [Department of Materials Science and Engineering, University of Texas at Dallas. 800 West Campbell Rd, Richardson, TX 75083 (United States); Quevedo-Lopez, M.A., E-mail: mxq071000@utdallas.edu [Department of Materials Science and Engineering, University of Texas at Dallas. 800 West Campbell Rd, Richardson, TX 75083 (United States)

    2012-01-31

    In this paper we demonstrate p-type thin film transistors fabricated with lead sulfide (PbS) as semiconductor deposited by chemical bath deposition methods. Crystallinity and morphology of the resulting PbS films were characterized using X-ray diffraction, atomic force microscopy and scanning electron microscopy. Devices were fabricated using photolithographic processes in a bottom gate configuration with Au as source and drain top contacts. Field effect mobility for as-fabricated devices was {approx} 0.09 cm{sup 2} V{sup -1} s{sup -1} whereas the mobility for devices annealed at 150 Degree-Sign C/h in forming gas increased up to {approx} 0.14 cm{sup 2} V{sup -1} s{sup -1}. Besides the thermal annealing, the entire fabrications process was maintained below 100 Degree-Sign C. The electrical performance of the PbS-thin film transistors was studied before and after the 150 Degree-Sign C anneal as well as a function of the PbS active layer thicknesses. - Highlights: Black-Right-Pointing-Pointer Thin film transistors with PbS as semiconductor deposited by chemical bath deposition. Black-Right-Pointing-Pointer Photolithography-based thin film transistors with PbS films at low temperatures. Black-Right-Pointing-Pointer Electron mobility for anneal-PbS devices of {approx} 0.14 cm{sup 2} V{sup -1} s{sup -1}. Black-Right-Pointing-Pointer Highest mobility reported in thin film transistors with PbS as the semiconductor.

  3. Percolation model for a selective response of the resistance of composite semiconducting np systems with respect to reducing gases

    Science.gov (United States)

    Russ, Stefanie

    2014-08-01

    It is shown that a two-component percolation model on a simple cubic lattice can explain an experimentally observed behavior [Savage et al., Sens. Actuators B 79, 17 (2001), 10.1016/S0925-4005(01)00843-7; Sens. Actuators B 72, 239 (2001)., 10.1016/S0925-4005(00)00676-6], namely, that a network built up by a mixture of sintered nanocrystalline semiconducting n and p grains can exhibit selective behavior, i.e., respond with a resistance increase when exposed to a reducing gas A and with a resistance decrease in response to another reducing gas B. To this end, a simple model is developed, where the n and p grains are simulated by overlapping spheres, based on realistic assumptions about the gas reactions on the grain surfaces. The resistance is calculated by random walk simulations with nn, pp, and np bonds between the grains, and the results are found in very good agreement with the experiments. Contrary to former assumptions, the np bonds are crucial to obtain this accordance.

  4. Construction of a photovoltaic cell based on the photoelectrochemistry of organic dyes at transparent semi-conducting electrodes. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Nasielski, J; Kirsch-De Mesmaeker, A

    1982-01-01

    It is shown that the study of the photoelectrochemical mechanisms of different dye-reductant systems at transparent semi-conducting bubbling gas electrodes, coupled with a detailed analysis of the photovoltammetric curves, allows: a deeper insight into the operation principles of the corresponding dye photogalvanic cells; prediction of the parameters important for optimizing the cell operation; and working out of strategies for improving the cell output. In order to compare the behaviors of an adsorbed type dye (rhodamine-hydroquinone) with a solution type dye in a photogalvanic cell, the thionine-Fe/sup 2 +/ system was examined, including a detailed kinetic analysis of the photocurrents at the bubbling gas electrode as a function of several parameters. Photoelectrochemical mechanisms related to the sensitization and supersensitization in this system have thus been determined. Photoelectrochemical methods were applied to analyze other dye-reductant systems. The photoelectrochemisty of three triphenyl-methanes, methyl violet, crystal violet, and malachite green were examined at the bubbling gas electrode. These dyes produce photocurrents originating from the adsorbed molecules and behave very much like rhodamine. The photoelectrochemical behavior of the erythrosine-hydroquinone couple is also examined. For constructing photogalvanic cells, the CdS-on-SnO/sub 2/-cysteine system is found promising. (LEW)

  5. Crystal structure, dielectric, ferroelectric and energy storage properties of La-doped BaTiO3 semiconducting ceramics

    Directory of Open Access Journals (Sweden)

    Venkata Sreenivas Puli

    2015-09-01

    Full Text Available Polycrystalline La-doped BaTiO3 (Ba(1-xLax\tTiO3 [x=0,0.0005,0.001,0.003] ceramics (denoted as BTO,BLT1,BLT2,BLT3 were synthesized by conventional solid-state reaction method and characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, and Raman spectroscopy. XRD and Raman spectra revealed single-phase tetragonal perovskite crystalline structure. Well-saturated polarization–electric field (P–E hysteresis loops were observed with the measurement frequency of 50 Hz at room temperature and confirmed ferroelectric nature of these ceramics and a high recoverable electrical energy storage density of 0.350 J/cm3 with energy efficiency (n∼9%, which is useful in energy storage capacitor applications. Dielectric studies revealed anomalies around 415–420 K and near the Curie temperature. The latter is attributed to the ferroelectric to paraelectric phase transition. Better dielectric performances were obtained for La-doped samples sintered at 1350°C for 4 h. Grain growth is inhibited with lanthanum (La incorporation into the BTO lattice. Room temperature semiconducting behavior with positive temperature coefficient of resistivity (PTCR behavior at TC is attributed to electron compensation mechanism.

  6. Inorganic p-Type Semiconductors: Their Applications and Progress in Dye-Sensitized Solar Cells and Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Ming-Hsien Li

    2016-04-01

    Full Text Available Considering the increasing global demand for energy and the harmful ecological impact of conventional energy sources, it is obvious that development of clean and renewable energy is a necessity. Since the Sun is our only external energy source, harnessing its energy, which is clean, non-hazardous and infinite, satisfies the main objectives of all alternative energy strategies. With attractive features, i.e., good performance, low-cost potential, simple processibility, a wide range of applications from portable power generation to power-windows, photoelectrochemical solar cells like dye-sensitized solar cells (DSCs represent one of the promising methods for future large-scale power production directly from sunlight. While the sensitization of n-type semiconductors (n-SC has been intensively studied, the use of p-type semiconductor (p-SC, e.g., the sensitization of wide bandgap p-SC and hole transport materials with p-SC have also been attracting great attention. Recently, it has been proved that the p-type inorganic semiconductor as a charge selective material or a charge transport material in organometallic lead halide perovskite solar cells (PSCs shows a significant impact on solar cell performance. Therefore the study of p-type semiconductors is important to rationally design efficient DSCs and PSCs. In this review, recent published works on p-type DSCs and PSCs incorporated with an inorganic p-type semiconductor and our perspectives on this topic are discussed.

  7. A study of structural, electrical, and optical properties of p-type Zn-doped SnO2 films versus deposition and annealing temperature

    Science.gov (United States)

    Le, Tran; Phuc Dang, Huu; Luc, Quang Ho; Hieu Le, Van

    2017-04-01

    This study presents a detailed investigation of the structural, electrical, and optical properties of p-type Zn-doped SnO2 versus the deposition and annealing temperature. Using a direct-current (DC) magnetron sputtering method, p-type transparent conductive Zn-doped SnO2 (ZTO) films were deposited on quartz glass substrates. Zn dopants incorporated into the SnO2 host lattice formed the preferred dominant SnO2 (1 0 1) and (2 1 1) planes. X-ray photoelectron spectroscopy (XPS) was used for identifying the valence state of Zn in the ZTO film. The electrical property of ZTO films changed from n-type to p-type at the threshold temperature of 400 °C, and the films achieved extremely high conductivity at the optimum annealing temperature of 600 °C after annealing for 2 h. The best conductive property of the film was obtained on a 10 wt% ZnO-doped SnO2 target with a resistivity, hole concentration, and hole mobility of 0.22 Ω · cm, 7.19  ×  1018 cm-3, and 3.95 cm2 V-1 s-1, respectively. Besides, the average transmission of films was  >84%. The surface morphology of films was examined using scanning electron microscopy (SEM). Moreover, the acceptor level of Zn2+ was identified using photoluminescence spectra at room temperature. Current-voltage (I-V) characteristics revealed the behavior of a p-ZTO/n-Si heterojunction diode.

  8. Pyrochlore type semiconducting ceramic oxides in Ca-Ce-Ti-M-O system (M = Nb or Ta)-Structure, microstructure and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Deepa, M. [Materials and Minerals Division, National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019 (India); Prabhakar Rao, P., E-mail: padala_rao@yahoo.com [Materials and Minerals Division, National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019 (India); Radhakrishnan, A.N.; Sibi, K.S.; Koshy, Peter [Materials and Minerals Division, National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019 (India)

    2009-07-01

    A new series of pyrochlore type ceramic semiconducting oxides in Ca-Ce-Ti-M-O (M = Nb or Ta) system has been synthesized by the conventional ceramic route. The electrical conductivity measurements show that these oxides exhibit semiconducting behavior and the conductivity increases with the Ce content in the compound. Activation energy of the current carriers is in the range of 0.5-1.6 eV. The electrical conductivity in these oxides is due to the presence of Ce{sup 3+}, which remains in the reduced state without being oxidized to Ce{sup 4+} by structural stabilization. The photoluminescence and X-ray photoelectron spectroscopy analysis corroborate the presence of Ce in the 3+ state. Impedance spectral analysis is carried out to evaluate the transport properties and indicates that the conduction in these compounds is mainly due to electronic contribution. The X-ray powder diffraction and Raman spectroscopy analysis establishes that these oxides belong to a cubic pyrochlore type structure.

  9. Piezoelectric and semiconducting coupled power generating process of a single ZnO belt/wire. A technology for harvesting electricity from the environment.

    Science.gov (United States)

    Song, Jinhui; Zhou, Jun; Wang, Zhong Lin

    2006-08-01

    This paper presents the experimental observation of piezoelectric generation from a single ZnO wire/belt for illustrating a fundamental process of converting mechanical energy into electricity at nanoscale. By deflecting a wire/belt using a conductive atomic force microscope tip in contact mode, the energy is first created by the deflection force and stored by piezoelectric potential, and later converts into piezoelectric energy. The mechanism of the generator is a result of coupled semiconducting and piezoelectric properties of ZnO. A piezoelectric effect is required to create electric potential of ionic charges from elastic deformation; semiconducting property is necessary to separate and maintain the charges and then release the potential via the rectifying behavior of the Schottky barrier at the metal-ZnO interface, which serves as a switch in the entire process. The good conductivity of ZnO is rather unique because it makes the current flow possible. This paper demonstrates a principle for harvesting energy from the environment. The technology has the potential of converting mechanical movement energy (such as body movement, muscle stretching, blood pressure), vibration energy (such as acoustic/ultrasonic wave), and hydraulic energy (such as flow of body fluid, blood flow, contraction of blood vessels) into electric energy that may be sufficient for self-powering nanodevices and nanosystems in applications such as in situ, real-time, and implantable biosensing, biomedical monitoring, and biodetection.

  10. Proton Pumping and Slippage Dynamics of a Eukaryotic P-Type ATPase Studied at the Single-Molecule Level

    DEFF Research Database (Denmark)

    Veshaguri, Salome

    In all eukaryotes the plasma membrane potential and secondary transport systems are energized by P-type ATPases whose regulation however remains poorly understood. Here we monitored at the single-molecule level the activity of the prototypic proton pumping P-type ATPase Arabidopsis thaliana isoform....... We propose that variable ATP/H+ stoichiometry emerges as a novel mechanism for adaptation when challenged with depletion of ATP that is likely relevant for other ATPases. Such measurements will provide indispensable insights into the mechanisms of function and regulation of many other ion...

  11. Effects of vacuum annealing on the optical and electrical properties of p-type copper-oxide thin-film transistors

    International Nuclear Information System (INIS)

    Sohn, Joonsung; Song, Sang-Hun; Kwon, Hyuck-In; Nam, Dong-Woo; Cho, In-Tak; Lee, Jong-Ho; Cho, Eou-Sik

    2013-01-01

    We have investigated the effects of vacuum annealing on the optical and electrical properties of the p-type copper-oxide thin-film transistors (TFTs). The vacuum annealing of the copper-oxide thin-film was performed using the RF magnetron sputter at various temperatures. From the x-ray diffraction and UV-vis spectroscopy, it is demonstrated that the high-temperature vacuum annealing reduces the copper-oxide phase from CuO to Cu 2 O, and increases the optical transmittance in the visible part of the spectrum. The fabricated copper-oxide TFT does not exhibit the switching behavior under low-temperature vacuum annealing conditions. However, as the annealing temperature increases, the drain current begins to be modulated by a gate voltage, and the TFT exhibits a high current on–off ratio over 10 4 as the vacuum annealing temperature increases over 450 °C. These results show that the vacuum annealing process can be an effective method of simultaneously improving the optical and electrical performances in p-type copper-oxide TFTs. (paper)

  12. Empirical Equation Based Chirality (n, m Assignment of Semiconducting Single Wall Carbon Nanotubes from Resonant Raman Scattering Data

    Directory of Open Access Journals (Sweden)

    Md Shamsul Arefin

    2012-12-01

    Full Text Available This work presents a technique for the chirality (n, m assignment of semiconducting single wall carbon nanotubes by solving a set of empirical equations of the tight binding model parameters. The empirical equations of the nearest neighbor hopping parameters, relating the term (2n, m with the first and second optical transition energies of the semiconducting single wall carbon nanotubes, are also proposed. They provide almost the same level of accuracy for lower and higher diameter nanotubes. An algorithm is presented to determine the chiral index (n, m of any unknown semiconducting tube by solving these empirical equations using values of radial breathing mode frequency and the first or second optical transition energy from resonant Raman spectroscopy. In this paper, the chirality of 55 semiconducting nanotubes is assigned using the first and second optical transition energies. Unlike the existing methods of chirality assignment, this technique does not require graphical comparison or pattern recognition between existing experimental and theoretical Kataura plot.

  13. Empirical Equation Based Chirality (n, m) Assignment of Semiconducting Single Wall Carbon Nanotubes from Resonant Raman Scattering Data

    Science.gov (United States)

    Arefin, Md Shamsul

    2012-01-01

    This work presents a technique for the chirality (n, m) assignment of semiconducting single wall carbon nanotubes by solving a set of empirical equations of the tight binding model parameters. The empirical equations of the nearest neighbor hopping parameters, relating the term (2n− m) with the first and second optical transition energies of the semiconducting single wall carbon nanotubes, are also proposed. They provide almost the same level of accuracy for lower and higher diameter nanotubes. An algorithm is presented to determine the chiral index (n, m) of any unknown semiconducting tube by solving these empirical equations using values of radial breathing mode frequency and the first or second optical transition energy from resonant Raman spectroscopy. In this paper, the chirality of 55 semiconducting nanotubes is assigned using the first and second optical transition energies. Unlike the existing methods of chirality assignment, this technique does not require graphical comparison or pattern recognition between existing experimental and theoretical Kataura plot. PMID:28348319

  14. Influence of pressing on the nanostructure and electrical properties of semiconducting polymer nanolayers

    International Nuclear Information System (INIS)

    Park, Jiho; Kim, Hwajeong; Kim, Youngkyoo

    2010-01-01

    In this work we attempted to change the nanostructure and electrical properties of semiconducting polymer nanolayers by employing a nano-pressing technique. The semiconducting polymer nanolayers, which consist of poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C 61 (PCBM), were spin-coated on to a conducting polymer buffer layer coated on a transparent conducting oxide substrate. The coated P3HT:PCBM samples were precisely pressed using a nanopress system at 70 .deg. C. The nanostructures of the unpressed and the pressed P3HT:PCBM layers were investigated using a grazing incident angle X-ray diffraction (GIXD) system empowered by a synchrotron radiation source while the electrical properties of those samples were examined using a diode-type device. Results showed that the P3HT chain alignment was improved by pressing, accordingly, the device with the pressed layer exhibited enhanced charge transport characteristics.

  15. Dual Colorimetric and Fluorescent Authentication Based on Semiconducting Polymer Dots for Anticounterfeiting Applications.

    Science.gov (United States)

    Tsai, Wei-Kai; Lai, Yung-Sheng; Tseng, Po-Jung; Liao, Chia-Hsien; Chan, Yang-Hsiang

    2017-09-13

    Semiconducting polymer dots (Pdots) have recently emerged as a novel type of ultrabright fluorescent probes that can be widely used in analytical sensing and material science. Here, we developed a dual visual reagent based on Pdots for anticounterfeiting applications. We first designed and synthesized two types of photoswitchable Pdots by incorporating photochromic dyes with multicolor semiconducting polymers to modulate their emission intensities and wavelengths. The resulting full-color Pdot assays showed that the colorimetric and fluorescent dual-readout abilities enabled the Pdots to serve as an anticounterfeiting reagent with low background interference. We also doped these Pdots into flexible substrates and prepared these Pdots as inks for pen handwriting as well as inkjet printing. We further applied this reagent in printing paper and checks for high-security anticounterfeiting purposes. We believe that this dual-readout method based on Pdots will create a new avenue for developing new generations of anticounterfeiting technologies.

  16. Organic-inorganic hybrid materials as semiconducting channels in thin-film field-effect transistors

    Science.gov (United States)

    Kagan; Mitzi; Dimitrakopoulos

    1999-10-29

    Organic-inorganic hybrid materials promise both the superior carrier mobility of inorganic semiconductors and the processability of organic materials. A thin-film field-effect transistor having an organic-inorganic hybrid material as the semiconducting channel was demonstrated. Hybrids based on the perovskite structure crystallize from solution to form oriented molecular-scale composites of alternating organic and inorganic sheets. Spin-coated thin films of the semiconducting perovskite (C(6)H(5)C(2)H(4)NH(3))(2)SnI(4) form the conducting channel, with field-effect mobilities of 0.6 square centimeters per volt-second and current modulation greater than 10(4). Molecular engineering of the organic and inorganic components of the hybrids is expected to further improve device performance for low-cost thin-film transistors.

  17. Cashew nut shell liquid, a valuable raw material for generating semiconductive polyaniline nanofibers

    Directory of Open Access Journals (Sweden)

    Raiane Valenti Gonçalves

    2018-03-01

    Full Text Available Abstract Cashew nut shell liquid (CNSL is an abundant and renewable by-product of the cashew nut industry. It appears to be a valuable raw material for generating semiconductive polyaniline (PAni nanomaterial with enhanced thermal stability and well-defined nanofiber morphology following a polymerization dispersion process. This study confirms that CNSL acts as a soft template during PAni synthesis, leading to an improvement in the nanofiber aspect. CNSL also improves the thermal stability of the PAni nanomaterial. Moreover, CNSL is an effective surfactant that promotes and stabilizes the dispersion of PAni nanofibers within water, allowing the more ecofriendly preparation of PAni nanomaterial by substituting the commonly used organic solvent with aqueous media. Finally, although CNSL promotes the formation of the conductive emeraldine salt form of PAni, increasing CNSL concentrations appear to plasticize the PAni polymer, leading to reduced electrical conductivity. However, this reduction is not detrimental, and PAni nanofibers remain semiconductive even under high CNSL concentrations.

  18. Anomalous X-ray scattering studies on semiconducting and metallic glasses

    International Nuclear Information System (INIS)

    Hosokawa, S.; Pilgrim, W.C.; Berar, J.F.; Kohara, S.

    2012-01-01

    In order to explore local- and intermediate-range atomic structures of several semiconducting and metallic glasses, anomalous X-ray scattering (AXS) experiments were performed using an improved detecting system suitable for third-generation synchrotron radiation facilities, and the obtained data were analyzed using reverse Monte Carlo (RMC) modelling to obtain partial structure factors and to construct three-dimensional atomic configurations of these glasses. Examples of GeSe 2 semiconducting and Pd 40 Ni 40 P 20 metallic glasses are demonstrated to exhibit the feasibility of the combination of AXS and RMC techniques. Importance of an additional combination with neutron scattering is also described for alloys containing light elements. (authors)

  19. Biocompatible and totally disintegrable semiconducting polymer for ultrathin and ultralightweight transient electronics.

    Science.gov (United States)

    Lei, Ting; Guan, Ming; Liu, Jia; Lin, Hung-Cheng; Pfattner, Raphael; Shaw, Leo; McGuire, Allister F; Huang, Tsung-Ching; Shao, Leilai; Cheng, Kwang-Ting; Tok, Jeffrey B-H; Bao, Zhenan

    2017-05-16

    Increasing performance demands and shorter use lifetimes of consumer electronics have resulted in the rapid growth of electronic waste. Currently, consumer electronics are typically made with nondecomposable, nonbiocompatible, and sometimes even toxic materials, leading to serious ecological challenges worldwide. Here, we report an example of totally disintegrable and biocompatible semiconducting polymers for thin-film transistors. The polymer consists of reversible imine bonds and building blocks that can be easily decomposed under mild acidic conditions. In addition, an ultrathin (800-nm) biodegradable cellulose substrate with high chemical and thermal stability is developed. Coupled with iron electrodes, we have successfully fabricated fully disintegrable and biocompatible polymer transistors. Furthermore, disintegrable and biocompatible pseudo-complementary metal-oxide-semiconductor (CMOS) flexible circuits are demonstrated. These flexible circuits are ultrathin (<1 μm) and ultralightweight (∼2 g/m 2 ) with low operating voltage (4 V), yielding potential applications of these disintegrable semiconducting polymers in low-cost, biocompatible, and ultralightweight transient electronics.

  20. Ultrasensitive Detection of Proteins on Western Blots with Semiconducting Polymer Dots

    OpenAIRE

    Ye, Fangmao; Smith, Polina B.; Wu, Changfeng; Chiu, Daniel T.

    2013-01-01

    We demonstrate ultrasensitive fluorescence imaging of proteins on Western blots using a bright, compact, and orange-emitting semiconducting polymer dot (CN-PPV). We achieved a detection limit at the single-picogram level in dot blots; with conventional Western blotting, we detected 50 pg of transferrin and trypsin inhibitor after SDS-PAGE and transfer onto a PVDF membrane. Our method does not require any additional equipment or time compared to the conventional procedure with traditional fluo...

  1. Degradable conjugated polymers for the selective sorting of semiconducting carbon nanotubes

    Science.gov (United States)

    Gopalan, Padma; Arnold, Michael Scott; Kansiusarulsamy, Catherine Kanimozhi; Brady, Gerald Joseph; Shea, Matthew John

    2018-04-10

    Conjugated polymers composed of bi-pyridine units linked to 9,9-dialkyl fluorenyl-2,7-diyl units via imine linkages along the polymer backbone are provided. Also provided are semiconducting single-walled carbon nanotubes coated with the conjugated polymers and methods of sorting and separating s-SWCNTs from a sample comprising a mixture of s-SWCNTs and metallic single-walled carbon nanotubes using the conjugated polymers.

  2. Charge Transport in Two-Photon Semiconducting Structures for Solar Fuels

    OpenAIRE

    Liu, Guohua; Du, Kang; Haussener, Sophia; Wang, Kaiying

    2016-01-01

    Semiconducting heterostructures are emerging as promising light absorbers and offer effective electron–hole separation to drive solar chemistry. This technology relies on semiconductor composites or photoelectrodes that work in the presence of a redox mediator and that create cascade junctions to promote surface catalytic reactions. Rational tuning of their structures and compositions is crucial to fully exploit their functionality. In this review, we describe the possibilities of applying th...

  3. Polarization-induced renormalization of molecular levels at metallic and semiconducting surfaces

    DEFF Research Database (Denmark)

    García Lastra, Juan Maria; Rostgaard, Carsten; Rubio, A.

    2009-01-01

    On the basis of first-principles G0W0 calculations we systematically study how the electronic levels of a benzene molecule are renormalized by substrate polarization when physisorbed on different metallic and semiconducting surfaces. The polarization-induced reduction in the energy gap between oc...... find that error cancellations lead to remarkably good agreement between the G0W0 and Kohn-Sham energies for the occupied orbitals of the adsorbed molecule....

  4. Giant magnetoresistance and extraordinary magnetoresistance in inhomogeneous semiconducting DyNiBi

    OpenAIRE

    Casper, Frederick; Felser, Claudia

    2007-01-01

    The semiconducting half-Heulser compound DyNiBi shows a negative giant magnetoresistance (GMR) below 200 K. Except for a weak deviation, this magnetoresistance scales roughly with the square of the magnetization in the paramagnetic state, and is related to the metal-insulator transition. At low temperature, a positive magnetoresistance is found, which can be suppressed by high fields. The magnitude of the positive magnetoresistance changes slightly with the amount of impurity phase.

  5. Synthesis and semiconducting properties of tin(II) sulfide: Application to photocatalytic degradation of Rhodamine B under sun light

    Energy Technology Data Exchange (ETDEWEB)

    Kabouche, S. [Laboratory of Electrochemistry-Corrosion, Metallurgy and Inorganic Chemistry, Faculty of Chemistry, U.S.T.H.B., BP 32, Algiers, 16111 (Algeria); Bellal, B. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of the Chemistry, U.S.T.H.B., BP 32, Algiers, 16111 (Algeria); Louafi, Y. [Laboratory of Electrochemistry-Corrosion, Metallurgy and Inorganic Chemistry, Faculty of Chemistry, U.S.T.H.B., BP 32, Algiers, 16111 (Algeria); Trari, M., E-mail: solarchemistry@gmail.com [Laboratory of Storage and Valorization of Renewable Energies, Faculty of the Chemistry, U.S.T.H.B., BP 32, Algiers, 16111 (Algeria)

    2017-07-01

    We have investigated the semiconducting and photoelectrochemical properties of SnS grown by a template-free chemical route using thiourea as precursor. Tin(II) sulfide is characterized by X-ray diffraction, scanning electron microscopy, diffuse reflectance and Raman spectroscopy. The X-ray diffraction indicates an orthorhombic SnS phase (SG: Pbnm) with a crystallite size of 52 nm while the optical measurements give a direct band gap of 1.33 eV. The Mott–Schottky plot exhibits a linear behavior, characteristic of n-type conductivity with a flat band potential of 0.19 V{sub SCE} and a donor density of 4.12 × 10{sup 18} cm{sup -3}. The electrochemical impedance spectroscopy (EIS) measured in the range (10{sup -2}–5 × 10{sup 4} Hz) shows one semicircle attributed to the bulk resistance (R{sub b} = 20.37 kΩ cm{sup 2}). The conduction band, located at 4.84 eV below vacuum, is made up of Sn{sup 2+:}5p while the valence band (6.17 eV) derives mainly from S{sup 2-}: 3p character. The energy band diagram, constructed from the photoelectrochemical characterization, predicts the photodegradation of Rhodamine B on SnS by H{sub 2}O{sub 2} generated photoelectrochemically. 88.46% of the initial concentration (10 mg L{sup -1}) disappears after adsorption and 4 h of exposure to solar light. The photoactivity is nearly restored during the second cycle and follows a second order kinetic with a rate constant of 1.55 × 10{sup -3} mg{sup -1} L min{sup -1}. - Highlights: • The semiconducting properties of SnS synthesized by chemical route are studied. • The n type conductivity is evidenced by chrono-amperometry and photoelectrochemistry. • The conduction band, located at 4.84 eV below vacuum, is made up of Sn{sup 2+}: 5p. • SnS was successfully used for the Rhodamine B oxidation under sunlight.

  6. Radio frequency and linearity performance of transistors using high-purity semiconducting carbon nanotubes.

    Science.gov (United States)

    Wang, Chuan; Badmaev, Alexander; Jooyaie, Alborz; Bao, Mingqiang; Wang, Kang L; Galatsis, Kosmas; Zhou, Chongwu

    2011-05-24

    This paper reports the radio frequency (RF) and linearity performance of transistors using high-purity semiconducting carbon nanotubes. High-density, uniform semiconducting nanotube networks are deposited at wafer scale using our APTES-assisted nanotube deposition technique, and RF transistors with channel lengths down to 500 nm are fabricated. We report on transistors exhibiting a cutoff frequency (f(t)) of 5 GHz and with maximum oscillation frequency (f(max)) of 1.5 GHz. Besides the cutoff frequency, the other important figure of merit for the RF transistors is the device linearity. For the first time, we report carbon nanotube RF transistor linearity metrics up to 1 GHz. Without the use of active probes to provide the high impedance termination, the measurement bandwidth is therefore not limited, and the linearity measurements can be conducted at the frequencies where the transistors are intended to be operating. We conclude that semiconducting nanotube-based transistors are potentially promising building blocks for highly linear RF electronics and circuit applications.

  7. Polymer-Sorted Semiconducting Carbon Nanotube Networks for High-Performance Ambipolar Field-Effect Transistors

    Science.gov (United States)

    2014-01-01

    Efficient selection of semiconducting single-walled carbon nanotubes (SWNTs) from as-grown nanotube samples is crucial for their application as printable and flexible semiconductors in field-effect transistors (FETs). In this study, we use atactic poly(9-dodecyl-9-methyl-fluorene) (a-PF-1-12), a polyfluorene derivative with asymmetric side-chains, for the selective dispersion of semiconducting SWNTs with large diameters (>1 nm) from plasma torch-grown SWNTs. Lowering the molecular weight of the dispersing polymer leads to a significant improvement of selectivity. Combining dense semiconducting SWNT networks deposited from an enriched SWNT dispersion with a polymer/metal-oxide hybrid dielectric enables transistors with balanced ambipolar, contact resistance-corrected mobilities of up to 50 cm2·V–1·s–1, low ohmic contact resistance, steep subthreshold swings (0.12–0.14 V/dec) and high on/off ratios (106) even for short channel lengths (<10 μm). These FETs operate at low voltages (<3 V) and show almost no current hysteresis. The resulting ambipolar complementary-like inverters exhibit gains up to 61. PMID:25493421

  8. Crystallization of P-type ATPases by the High Lipid-Detergent (HiLiDe) Method

    DEFF Research Database (Denmark)

    Sitsel, Oleg; Wang, Kaituo; Liu, Xiangyu

    2016-01-01

    Determining structures of membrane proteins remains a significant challenge. A technique utilizing high lipid-detergent concentrations ("HiLiDe") circumvents the major bottlenecks of current membrane protein crystallization methods. During HiLiDe, the protein-lipid-detergent ratio is varied in a ...... crystallization techniques. The method has been applied with particular success to P-type ATPases....

  9. Micro Raman and photoluminescence spectroscopy of nano-porous n and p type GaN/sapphire(0001).

    Science.gov (United States)

    Ingale, Alka; Pal, Suparna; Dixit, V K; Tiwari, Pragya

    2007-06-01

    Variation of depth within a single etching spot (3 mm circular diameter) was observed in nanoporous GaN epilayer obtained on photo-assisted electrochemical etching of n and p-type GaN. The different etching depth regions were studied using microRaman and PL(yellow region) for both n-type and p-type GaN. From Raman spectroscopy, we observed that increase in disorder is accompanied by stress relaxation, as depth of etching increases for n-type GaN epilayer. This is well corroborated with scanning electron microscopy results. Contrarily, for p-type GaN epilayer we found that for minimum etching depth, stress in epilayer increases with increase in disorder. This is understood with the fact that as grown p-type GaN is more disordered compared to n-type GaN due to heavy Mg doping and further disorder leads to lattice distortion leading to increase in stress.

  10. Study of araldite in edge protection of n-type and p-type surface barrier detectors

    International Nuclear Information System (INIS)

    Alencar, M.A.V.; Jesus, E.F.O.; Lopes, R.T.

    1995-01-01

    The aim of this work is the realization of a comparative study between the surface barrier detectors performance n and type using the epoxy resin Araldite as edge protection material with the purpose of determining which type of detector (n or p) the use of Araldite is more indicated. The surface barrier detectors were constructed using n and p type silicon wafer with resistivity of 3350Ω.cm and 5850 Ω.cm respectively. In the n type detectors, the metals used as ohmic and rectifier contacts were the Al and Au respectively, while in the p type detectors, the ohmic and rectifier contacts were Au and Al. All metallic contacts were done by evaporation in high vacuum (∼10 -4 Torr) and with deposit of 40 μm/cm 2 . The obtained results for the detectors (reverse current of -350nA and resolution from 21 to 26 keV for p type detectors and reserve current of 1μA and resolution from 44 to 49 keV for n type detectors) tend to demonstrate that use of epoxy resin Araldite in the edge protection is more indicated to p type surface barrier detectors. (author). 3 refs., 4 figs., 1 tab

  11. Nanomechanical properties of thick porous silicon layers grown on p- and p+-type bulk crystalline Si

    International Nuclear Information System (INIS)

    Charitidis, C.A.; Skarmoutsou, A.; Nassiopoulou, A.G.; Dragoneas, A.

    2011-01-01

    Highlights: → The nanomechanical properties of bulk crystalline Si. → The nanomechanical properties of porous Si. → The elastic-plastic deformation of porous Si compared to bulk crystalline quantified by nanoindentation data analysis. - Abstract: The nanomechanical properties and the nanoscale deformation of thick porous Si (PSi) layers of two different morphologies, grown electrochemically on p-type and p+-type Si wafers were investigated by the depth-sensing nanoindentation technique over a small range of loads using a Berkovich indenter and were compared with those of bulk crystalline Si. The microstructure of the thick PSi layers was characterized by field emission scanning electron microscopy. PSi layers on p+-type Si show an anisotropic mesoporous structure with straight vertical pores of diameter in the range of 30-50 nm, while those on p-type Si show a sponge like mesoporous structure. The effect of the microstructure on the mechanical properties of the layers is discussed. It is shown that the hardness and Young's modulus of the PSi layers exhibit a strong dependence on their microstructure. In particular, PSi layers with the anisotropic straight vertical pores show higher hardness and elastic modulus values than sponge-like layers. However, sponge-like PSi layers reveal less plastic deformation and higher wear resistance compared with layers with straight vertical pores.

  12. In silico approaches and chemical space of anti-P-type ATPase compounds for discovering new antituberculous drugs.

    Science.gov (United States)

    Santos, Paola; López-Vallejo, Fabian; Soto, Carlos-Y

    2017-08-01

    Tuberculosis (TB) is one of the most important public health problems around the world. The emergence of multi-drug-resistant (MDR) and extensively drug-resistant (XDR) Mycobacterium tuberculosis strains has driven the finding of alternative anti-TB targets. In this context, P-type ATPases are interesting therapeutic targets due to their key role in ion homeostasis across the plasma membrane and the mycobacterial survival inside macrophages. In this review, in silico and experimental strategies used for the rational design of new anti-TB drugs are presented; in addition, the chemical space distribution based on the structure and molecular properties of compounds with anti-TB and anti-P-type ATPase activity is discussed. The chemical space distribution compared to public compound libraries demonstrates that natural product libraries are a source of novel chemical scaffolds with potential anti-P-type ATPase activity. Furthermore, compounds that experimentally display anti-P-type ATPase activity belong to a chemical space of molecular properties comparable to that occupied by those approved for oral use, suggesting that these kinds of molecules have a good pharmacokinetic profile (drug-like) for evaluation as potential anti-TB drugs. © 2017 John Wiley & Sons A/S.

  13. Demonstration of high-performance p-type tin oxide thin-film transistors using argon-plasma surface treatments

    Science.gov (United States)

    Bae, Sang-Dae; Kwon, Soo-Hun; Jeong, Hwan-Seok; Kwon, Hyuck-In

    2017-07-01

    In this work, we investigated the effects of low-temperature argon (Ar)-plasma surface treatments on the physical and chemical structures of p-type tin oxide thin-films and the electrical performance of p-type tin oxide thin-film transistors (TFTs). From the x-ray photoelectron spectroscopy measurement, we found that SnO was the dominant phase in the deposited tin oxide thin-film, and the Ar-plasma treatment partially transformed the tin oxide phase from SnO to SnO2 by oxidation. The resistivity of the tin oxide thin-film increased with the plasma-treatment time because of the reduced hole concentration. In addition, the root-mean-square roughness of the tin oxide thin-film decreased as the plasma-treatment time increased. The p-type oxide TFT with an Ar-plasma-treated tin oxide thin-film exhibited excellent electrical performance with a high current on-off ratio (5.2 × 106) and a low off-current (1.2 × 10-12 A), which demonstrates that the low-temperature Ar-plasma treatment is a simple and effective method for improving the electrical performance of p-type tin oxide TFTs.

  14. Preparation of p-type transparent conducting tin-antimony oxide thin films by DC reactive magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Zhenguo [College of Electronic Information, Hangzhou Dianzi University, Hangzhou (China); State Key Laboratory for Silicon Materials, Zhejiang University, Hangzhou (China); Xi, Junhua; Huo, Lijuan; Zhao, Yi [State Key Laboratory for Silicon Materials, Zhejiang University, Hangzhou (China)

    2008-07-01

    P-type transparent conducting tin-antimony oxide (TAO) films were successfully prepared by DC reactive magnetron sputtering followed by post annealing in the air. Structural, optical and electrical properties of the TAO films were investigated. X-ray diffraction studies showed that the films are polycrystalline with orthorhombic structure of Sb{sub 2}O{sub 4}. UV-Visible absorption and transmittance spectra showed that the optical band-gap of the TAO films is about 3.90 eV, and the overall transmittance is higher than 85% in the visible region. Hall effect measurement indicated that the Sn/Sb ratio is a critical parameter to get p-type conducting TAO films. It was found that 0.19p-type TAO films could be obtained. Hole concentration as high as 4.03 x 10{sup 19} cm{sup -3} and electrical resistivity as low as 0.155 {omega}cm were achieved, showing potential applications of TAO films as p-type transparent conducting films. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. S-type and P-type habitability in stellar binary systems: A comprehensive approach. I. Method and applications

    Energy Technology Data Exchange (ETDEWEB)

    Cuntz, M., E-mail: cuntz@uta.edu [Department of Physics, University of Texas at Arlington, Arlington, TX 76019-0059 (United States)

    2014-01-01

    A comprehensive approach is provided for the study of both S-type and P-type habitability in stellar binary systems, which in principle can also be expanded to systems of higher order. P-type orbits occur when the planet orbits both binary components, whereas in the case of S-type orbits, the planet orbits only one of the binary components with the second component considered a perturbator. The selected approach encapsulates a variety of different aspects, which include: (1) the consideration of a joint constraint, including orbital stability and a habitable region for a putative system planet through the stellar radiative energy fluxes ({sup r}adiative habitable zone{sup ;} RHZ), needs to be met; (2) the treatment of conservative, general, and extended zones of habitability for the various systems as defined for the solar system and beyond; (3) the provision of a combined formalism for the assessment of both S-type and P-type habitability; in particular, mathematical criteria are presented for the kind of system in which S-type and P-type habitability is realized; (4) applications of the attained theoretical approach to standard (theoretical) main-sequence stars. In principle, five different cases of habitability are identified, which are S-type and P-type habitability provided by the full extent of the RHZs; habitability, where the RHZs are truncated by the additional constraint of planetary orbital stability (referred to as ST- and PT-type, respectively); and cases of no habitability at all. Regarding the treatment of planetary orbital stability, we utilize the formulae of Holman and Wiegert as also used in previous studies. In this work, we focus on binary systems in circular orbits. Future applications will also consider binary systems in elliptical orbits and provide thorough comparisons to other methods and results given in the literature.

  16. Evidence for bifurcation and universal chaotic behavior in nonlinear semiconducting devices

    International Nuclear Information System (INIS)

    Testa, J.; Perez, J.; Jeffries, C.

    1982-01-01

    Bifurcations, chaos, and extensive periodic windows in the chaotic regime are observed for a driven LRC circuit, the capacitive element being a nonlinear varactor diode. Measurements include power spectral analysis; real time amplitude data; phase portraits; and a bifurcation diagram, obtained by sampling methods. The effects of added external noise are studied. These data yield experimental determinations of several of the universal numbers predicted to characterize nonlinear systems having this route to chaos

  17. Structural Ordering of Semiconducting Polymers and Small-Molecules for Organic Electronics

    Science.gov (United States)

    O'Hara, Kathryn Allison

    Semiconducting polymers and small-molecules can be readily incorporated into electronic devices such as organic photovoltaics (OPVs), thermoelectrics (OTEs), organic light emitting diodes (OLEDs), and organic thin film transistors (OTFTs). Organic materials offer the advantage of being processable from solution to form flexible and lightweight thin films. The molecular design, processing, and resulting thin film morphology of semiconducting polymers drastically affect the optical and electronic properties. Charge transport within films of semiconducting polymers relies on the nanoscale organization to ensure electronic coupling through overlap of molecular orbitals and to provide continuous transport pathways. While the angstrom-scale packing details can be studied using X-ray scattering methods, an understanding of the mesoscale, or the length scale over which smaller ordered regions connect, is much harder to achieve. Grain boundaries play an important role in semiconducting polymer thin films where the average grain size is much smaller than the total distance which charges must traverse in order to reach the electrodes in a device. The majority of semiconducting polymers adopt a lamellar packing structure in which the conjugated backbones align in parallel pi-stacks separated by the alkyl side-chains. Only two directions of transport are possible--along the conjugated backbone and in the pi-stacking direction. Currently, the discussion of transport between crystallites is centered around the idea of tie-chains, or "bridging" polymer chains connecting two ordered regions. However, as molecular structures become increasingly complex with the development of new donor-acceptor copolymers, additional forms of connectivity between ordered domains should be considered. High resolution transmission electron microscopy (HRTEM) is a powerful tool for directly imaging the crystalline grain boundaries in polymer and small-molecule thin films. Recently, structures

  18. Resonance Raman spectra of organic molecules absorbed on inorganic semiconducting surfaces: Contribution from both localized intramolecular excitation and intermolecular charge transfer excitation

    International Nuclear Information System (INIS)

    Ye, ChuanXiang; Zhao, Yi; Liang, WanZhen

    2015-01-01

    The time-dependent correlation function approach for the calculations of absorption and resonance Raman spectra (RRS) of organic molecules absorbed on semiconductor surfaces [Y. Zhao and W. Z. Liang, J. Chem. Phys. 135, 044108 (2011)] is extended to include the contribution of the intermolecular charge transfer (CT) excitation from the absorbers to the semiconducting nanoparticles. The results demonstrate that the bidirectionally interfacial CT significantly modifies the spectral line shapes. Although the intermolecular CT excitation makes the absorption spectra red shift slightly, it essentially changes the relative intensities of mode-specific RRS and causes the oscillation behavior of surface enhanced Raman spectra with respect to interfacial electronic couplings. Furthermore, the constructive and destructive interferences of RRS from the localized molecular excitation and CT excitation are observed with respect to the electronic coupling and the bottom position of conductor band. The interferences are determined by both excitation pathways and bidirectionally interfacial CT

  19. Surface States and Effective Surface Area on Photoluminescent P-Type Porous Silicon

    Science.gov (United States)

    Weisz, S. Z.; Porras, A. Ramirez; Resto, O.; Goldstein, Y.; Many, A.; Savir, E.

    1997-01-01

    The present study is motivated by the possibility of utilizing porous silicon for spectral sensors. Pulse measurements on the porous-Si/electrolyte system are employed to determine the surface effective area and the surface-state density at various stages of the anodization process used to produce the porous material. Such measurements were combined with studies of the photoluminescence spectra. These spectra were found to shift progressively to the blue as a function of anodization time. The luminescence intensity increases initially with anodization time, reaches a maximum and then decreases with further anodization. The surface state density, on the other hand, increases with anodization time from an initial value of about 2 x 10(exp 12)/sq cm surface to about 1013 sq cm for the anodized surface. This value is attained already after -2 min anodization and upon further anodization remains fairly constant. In parallel, the effective surface area increases by a factor of 10-30. This behavior is markedly different from the one observed previously for n-type porous Si.

  20. Spin dynamics of light-induced charge separation in composites of semiconducting polymers and PC60BM revealed using Q-band pulse EPR.

    Science.gov (United States)

    Lukina, E A; Suturina, E; Reijerse, E; Lubitz, W; Kulik, L V

    2017-08-23

    Light-induced processes in composites of semiconducting polymers and fullerene derivatives have been widely studied due to their usage as active layers of organic solar cells. However the process of charge separation under light illumination - the key process of an organic solar cell is not well understood yet. Here we report a Q-band pulse electron paramagnetic resonance study of composites of the fullerene derivative PC 60 BM ([6,6]-phenyl-C 61 -butyric acid methyl ester) with different p-type semiconducting polymers regioregular and regiorandom P3HT (poly(3-hexylthiophene-2,5-diyl), MEH-PPV (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]), PCDTBT (poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)]), PTB7 (poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}))), resulting in a detailed description of the in-phase laser flash-induced electron spin echo (ESE) signal. We found that in organic donor-acceptor composites the laser flash simultaneously induces species of two types: a polymer˙ + /fullerene˙ - spin-correlated polaron pair (SCPP) with an initial singlet spin state and (nearly) free polymer˙ + and fullerene˙ - species with non-equilibrium spin polarization. Species of the first type (SCPP) are well-known for polymer/fullerene blends and are usually associated with a charge-separated state. Also, spin polarization of long-living free species (polarons in deep traps) is affected by the laser flash, which is the third contribution to the flash-induced ESE signal. A protocol for extracting the in-phase ESE signal of the SCPP based on the dependence of the microwave nutation frequency on the strength of the spin coupling within the polaron pair was developed. Nutation experiments revealed an unusual pattern of the SCPP in RR-P3HT/PC 60 BM composites, from which the strength of the exchange interaction between the polymer

  1. Behaviorism

    Science.gov (United States)

    Moore, J.

    2011-01-01

    Early forms of psychology assumed that mental life was the appropriate subject matter for psychology, and introspection was an appropriate method to engage that subject matter. In 1913, John B. Watson proposed an alternative: classical S-R behaviorism. According to Watson, behavior was a subject matter in its own right, to be studied by the…

  2. a-Si:H/c-Si heterojunction front- and back contacts for silicon solar cells with p-type base

    Energy Technology Data Exchange (ETDEWEB)

    Rostan, Philipp Johannes

    2010-07-01

    internal quantum efficiency shows that both types of back contacts lead to effective diffusion lengths in excess of 600 {mu}m. An extended fill factor analysis shows that fill factor limitations for the full-area a-Si:H/c-Si contacts result from non-ideal diode behavior, ascribed to the injection dependence of the heterojunction interface recombination velocity. Analysis of the external quantum efficiency under back side illumination with different bias light intensities delivers the effective surface recombination S{sub eff}({phi}) in dependance of the illumination intensity {phi}. The front contact (emitter) uses a sequence of intrinsic and phosphorous doped amorphous silicon layers together with a ZnO:Al or a SnO{sub 2}:In layer and an Al front contact grid. The emitter is prepared at a maximum temperature of 220 C. Measurements of the minority carrier lifetime on symmetric i/n-a-Si:H coated wafers judge the emitter passivation quality. The best solar cells that use a thermal oxide back side passivation with Al-point contacts and flat a-Si:H emitters have open circuit voltages up to 683 mV and efficiencies up to 17.4 %. The efficiency of such devices is limited by a low short circuit current due to the flat front side. Using the same back contact structure with random pyramid textured wafer front sides and a-Si:H emitters yields open circuit voltages up to 660 mV and efficiencies up to 18.5 %, so far limited by a relatively low fill factor FF {<=} 74.3 %. Analysis of the external quantum efficiency underlines the excellent surface passivation properties of the amorphous emitter. Combining both, amorphous front- and back contacts yields p-type heterojunction solar cells completely fabricated at temperatures below 220 C. The best devices reach an open circuit voltage V{sub oc} = 678 mV and an efficiency {eta} = 18.1 % with random textured wafers, limited by low fill factors FF {approx} 75 %. Besides the cell fabrication and characterization, this thesis reveals that the

  3. Fitting Formulae and Constraints for the Existence of S-type and P-type Habitable Zones in Binary Systems

    International Nuclear Information System (INIS)

    Wang Zhaopeng; Cuntz, Manfred

    2017-01-01

    We derive fitting formulae for the quick determination of the existence of S-type and P-type habitable zones (HZs) in binary systems. Based on previous work, we consider the limits of the climatological HZ in binary systems (which sensitively depend on the system parameters) based on a joint constraint encompassing planetary orbital stability and a habitable region for a possible system planet. Additionally, we employ updated results on planetary climate models obtained by Kopparapu and collaborators. Our results are applied to four P-type systems (Kepler-34, Kepler-35, Kepler-413, and Kepler-1647) and two S-type systems (TrES-2 and KOI-1257). Our method allows us to gauge the existence of climatological HZs for these systems in a straightforward manner with detailed consideration of the observational uncertainties. Further applications may include studies of other existing systems as well as systems to be identified through future observational campaigns.

  4. Strong compensation hinders the p-type doping of ZnO: a glance over surface defect levels

    Science.gov (United States)

    Huang, B.

    2016-07-01

    We propose a surface doping model of ZnO to elucidate the p-type doping and compensations in ZnO nanomaterials. With an N-dopant, the effects of N on the ZnO surface demonstrate a relatively shallow acceptor level in the band gap. As the dimension of the ZnO materials decreases, the quantum confinement effects will increase and render the charge transfer on surface to influence the shifting of Fermi level, by evidence of transition level changes of the N-dopant. We report that this can overwhelm the intrinsic p-type conductivity and transport of the ZnO bulk system. This may provide a possible route of using surface doping to modify the electronic transport and conductivity of ZnO nanomaterials.

  5. Structural models of the human copper P-type ATPases ATP7A and ATP7B

    DEFF Research Database (Denmark)

    Gourdon, P.; Sitsel, Oleg; Karlsen, J.L.

    2012-01-01

    The human copper exporters ATP7A and ATP7B contain domains common to all P-type ATPases as well as class-specific features such as six sequential heavy-metal binding domains (HMBD1-HMBD6) and a type-specific constellation of transmembrane helices. Despite the medical significance of ATP7A and ATP7B......, allowing protein-specific properties to be addressed. Furthermore, the mapping of known disease-causing missense mutations indicates that among the heavy-metal binding domains, HMBD5 and HMBD6 are the most crucial for function, thus mimicking the single or dual HMBDs found in most copper-specific P-type...

  6. Influence of hydrogen impurities on p-type resistivity in Mg-doped GaN films

    International Nuclear Information System (INIS)

    Yang, Jing; Zhao, Degang; Jiang, Desheng; Chen, Ping; Zhu, Jianjun; Liu, Zongshun; Le, Lingcong; He, Xiaoguang; Li, Xiaojing; Zhang, Y. T.; Du, G. T.

    2015-01-01

    The effects of hydrogen impurities on p-type resistivity in Mg-doped GaN films were investigated. It was found that hydrogen impurities may have the dual role of passivating Mg Ga acceptors and passivating donor defects. A decrease in p-type resistivity when O 2 is introduced during the postannealing process is attributed to the fact that annealing in an O 2 -containing environment can enhance the dissociation of Mg Ga -H complexes as well as the outdiffusion of H atoms from p-GaN films. However, low H concentrations are not necessarily beneficial in Mg-doped GaN films, as H atoms may also be bound at donor species and passivate them, leading to the positive effect of reduced compensation

  7. Analysis of Photoluminescence Thermal Quenching: Guidance for the Design of Highly Effective p-type Doping of Nitrides

    Science.gov (United States)

    Liu, Zhiqiang; Huang, Yang; Yi, Xiaoyan; Fu, Binglei; Yuan, Guodong; Wang, Junxi; Li, Jinmin; Zhang, Yong

    2016-08-01

    A contact-free diagnostic technique for examining position of the impurity energy level of p-type dopants in nitride semiconductors was proposed based on photoluminescence thermal quenching. The Mg ionization energy was extracted by the phenomenological rate-equation model we developed. The diagnostic technique and analysis model reported here are priorities for the design of highly effective p-doping of nitrides and could also be used to explain the abnormal and seldom analyzed low characteristic temperature T0 (about 100 K) of thermal quenching in p-type nitrides systems. An In-Mg co-doped GaN system is given as an example to prove the validity of our methods. Furthermore, a hole concentration as high as 1.94 × 1018 cm-3 was achieved through In-Mg co-doping, which is nearly one order of magnitude higher than typically obtained in our lab.

  8. Fitting Formulae and Constraints for the Existence of S-type and P-type Habitable Zones in Binary Systems

    Energy Technology Data Exchange (ETDEWEB)

    Wang Zhaopeng; Cuntz, Manfred, E-mail: zhaopeng.wang@mavs.uta.edu, E-mail: cuntz@uta.edu [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States)

    2017-10-01

    We derive fitting formulae for the quick determination of the existence of S-type and P-type habitable zones (HZs) in binary systems. Based on previous work, we consider the limits of the climatological HZ in binary systems (which sensitively depend on the system parameters) based on a joint constraint encompassing planetary orbital stability and a habitable region for a possible system planet. Additionally, we employ updated results on planetary climate models obtained by Kopparapu and collaborators. Our results are applied to four P-type systems (Kepler-34, Kepler-35, Kepler-413, and Kepler-1647) and two S-type systems (TrES-2 and KOI-1257). Our method allows us to gauge the existence of climatological HZs for these systems in a straightforward manner with detailed consideration of the observational uncertainties. Further applications may include studies of other existing systems as well as systems to be identified through future observational campaigns.

  9. S-TYPE AND P-TYPE HABITABILITY IN STELLAR BINARY SYSTEMS: A COMPREHENSIVE APPROACH. II. ELLIPTICAL ORBITS

    Energy Technology Data Exchange (ETDEWEB)

    Cuntz, M., E-mail: cuntz@uta.edu [Department of Physics, University of Texas at Arlington, Arlington, TX 76019-0059 (United States)

    2015-01-10

    In the first paper of this series, a comprehensive approach has been provided for the study of S-type and P-type habitable regions in stellar binary systems, which was, however, restricted to circular orbits of the stellar components. Fortunately, a modest modification of the method also allows for the consideration of elliptical orbits, which of course entails a much broader range of applicability. This augmented method is presented here, and numerous applications are conveyed. In alignment with Paper I, the selected approach considers a variety of aspects, which comprise the consideration of a joint constraint including orbital stability and a habitable region for a possible system planet through the stellar radiative energy fluxes ({sup r}adiative habitable zone{sup ;} RHZ). The devised method is based on a combined formalism for the assessment of both S-type and P-type habitability; in particular, mathematical criteria are deduced for which kinds of systems S-type and P-type habitable zones are realized. If the RHZs are truncated by the additional constraint of orbital stability, the notation of ST-type and PT-type habitability applies. In comparison to the circular case, it is found that in systems of higher eccentricity, the range of the RHZs is significantly reduced. Moreover, for a considerable number of models, the orbital stability constraint also reduces the range of S-type and P-type habitability. Nonetheless, S-, P-, ST-, and PT-type habitability is identified for a considerable set of system parameters. The method as presented is utilized for BinHab, an online code available at The University of Texas at Arlington.

  10. Direct Evidence of Mg Incorporation Pathway in Vapor-Liquid-Solid Grown p-type Nonpolar GaN Nanowires

    OpenAIRE

    Patsha, Avinash; Amirthapandian, S.; Pandian, Ramanathaswamy; Bera, S.; Bhattacharya, Anirban; Dhara, Sandip

    2015-01-01

    Doping of III-nitride based compound semiconductor nanowires is still a challenging issue to have a control over the dopant distribution in precise locations of the nanowire optoelectronic devices. Knowledge of the dopant incorporation and its pathways in nanowires for such devices is limited by the growth methods. We report the direct evidence of incorporation pathway for Mg dopants in p-type nonpolar GaN nanowires grown via vapour-liquid-solid (VLS) method in a chemical vapour deposition te...

  11. S-TYPE AND P-TYPE HABITABILITY IN STELLAR BINARY SYSTEMS: A COMPREHENSIVE APPROACH. II. ELLIPTICAL ORBITS

    International Nuclear Information System (INIS)

    Cuntz, M.

    2015-01-01

    In the first paper of this series, a comprehensive approach has been provided for the study of S-type and P-type habitable regions in stellar binary systems, which was, however, restricted to circular orbits of the stellar components. Fortunately, a modest modification of the method also allows for the consideration of elliptical orbits, which of course entails a much broader range of applicability. This augmented method is presented here, and numerous applications are conveyed. In alignment with Paper I, the selected approach considers a variety of aspects, which comprise the consideration of a joint constraint including orbital stability and a habitable region for a possible system planet through the stellar radiative energy fluxes ( r adiative habitable zone ; RHZ). The devised method is based on a combined formalism for the assessment of both S-type and P-type habitability; in particular, mathematical criteria are deduced for which kinds of systems S-type and P-type habitable zones are realized. If the RHZs are truncated by the additional constraint of orbital stability, the notation of ST-type and PT-type habitability applies. In comparison to the circular case, it is found that in systems of higher eccentricity, the range of the RHZs is significantly reduced. Moreover, for a considerable number of models, the orbital stability constraint also reduces the range of S-type and P-type habitability. Nonetheless, S-, P-, ST-, and PT-type habitability is identified for a considerable set of system parameters. The method as presented is utilized for BinHab, an online code available at The University of Texas at Arlington

  12. Change in the electrical conductivity of SnO2 crystal from n-type to p-type conductivity

    International Nuclear Information System (INIS)

    Villamagua, Luis; Stashans, Arvids; Lee, Po-Ming; Liu, Yen-Shuo; Liu, Cheng-Yi; Carini, Manuela

    2015-01-01

    Highlights: • Switch from n-type to p-type conductivity in SnO 2 has been studied. • Computational DFT + U method where used. • X-ray diffraction and X-ray photoelectron spectroscopy where used. • Al- and N-codoped SnO 2 compound shows stable p-type conductivity. • Low resistivity (3.657 × 10 −1 Ω cm) has been obtained. • High carrier concentration (4.858 × 10 19 cm −3 ) has been obtained. - Abstract: The long-sought fully transparent technology will not come true if the n region of the p–n junction does not get as well developed as its p counterpart. Both experimental and theoretical efforts have to be used to study and discover phenomena occurring at the microscopic level in SnO 2 systems. In the present paper, using the DFT + U approach as a main tool and the Vienna ab initio Simulation Package (VASP) we reproduce both intrinsic n-type as well as p-type conductivity in concordance to results observed in real samples of SnO 2 material. Initially, an oxygen vacancy (1.56 mol% concentration) combined with a tin-interstitial (1.56 mol% concentration) scheme was used to achieve the n-type electrical conductivity. Later, to attain the p-type conductivity, crystal already possessing n-type conductivity, was codoped with nitrogen (1.56 mol% concentration) and aluminium (12.48 mol% concentration) impurities. Detailed explanation of structural changes endured by the geometry of the crystal as well as the changes in its electrical properties has been obtained. Our experimental data to a very good extent matches with the results found in the DFT + U modelling

  13. Field effect transistors and phototransistors based upon p-type solution-processed PbS nanowires

    Science.gov (United States)

    Giraud, Paul; Hou, Bo; Pak, Sangyeon; Inn Sohn, Jung; Morris, Stephen; Cha, SeungNam; Kim, Jong Min

    2018-02-01

    We demonstrate the fabrication of solution processed highly crystalline p-type PbS nanowires via the oriented attachment of nanoparticles. The analysis of single nanowire field effect transistor (FET) devices revealed a hole conduction behaviour with average mobilities greater than 30 cm2 V-1 s-1, which is an order of magnitude higher than that reported to date for p-type PbS colloidal nanowires. We have investigated the response of the FETs to near-infrared light excitation and show herein that the nanowires exhibited gate-dependent photo-conductivities, enabling us to tune the device performances. The responsivity was found to be greater than 104 A W-1 together with a detectivity of 1013 Jones, which benefits from a photogating effect occurring at negative gate voltages. These encouraging detection parameters are accompanied by relatively short switching times of 15 ms at positive gate voltages, resulting from a combination of the standard photoconduction and the high crystallinity of the nanowires. Collectively, these results indicate that solution-processed PbS nanowires are promising nanomaterials for infrared photodetectors as well as p-type nanowire FETs.

  14. Thermal Stability of P-Type BiSbTe Alloys Prepared by Melt Spinning and Rapid Sintering

    Directory of Open Access Journals (Sweden)

    Yun Zheng

    2017-06-01

    Full Text Available P-type BiSbTe alloys have been widely implemented in waste heat recovery from low-grade heat sources below 600 K, which may involve assorted environments and conditions, such as long-term service, high-temperature exposure (generally 473–573 K and mechanical forces. It is important to evaluate the service performance of these materials in order to prevent possible failures in advance and extend the life cycle. In this study, p-type Bi0.5Sb1.5Te3 commercial zone-melting (ZM ingots were processed by melt spinning and subsequent plasma-activated sintering (MS-PAS, and were then subjected to vacuum-annealing at 473 and 573 K, respectively, for one week. The results show that MS-PAS samples exhibit excellent thermal stability when annealed at 473 K. However, thermal annealing at 573 K for MS-PAS specimens leads to the distinct sublimation of the element Te, which degrades the hole concentration remarkably and results in inferior thermoelectric performance. Furthermore, MS-PAS samples annealed at 473 K demonstrate a slight enhancement in flexural and compressive strengths, probably due to the reduction of residual stress induced during the sintering process. The current work guides the reliable application of p-type Bi0.5Sb1.5Te3 compounds prepared by the MS-PAS technique.

  15. Excellent Passivation of p-Type Si Surface by Sol-Gel Al2O3 Films

    International Nuclear Information System (INIS)

    Hai-Qing, Xiao; Chun-Lan, Zhou; Xiao-Ning, Cao; Wen-Jing, Wang; Lei, Zhao; Hai-Ling, Li; Hong-Wei, Diao

    2009-01-01

    Al 2 O 3 films with a thickness of about 100 nm synthesized by spin coating and thermally treated are applied for field-induced surface passivation of p-type crystalline silicon. The level of surface passivation is determined by techniques based on photoconductance. An effective surface recombination velocity below 100 cm/s is obtained on 10Ω ·cm p-type c-Si wafers (Cz Si). A high density of negative fixed charges in the order of 10 12 cm −2 is detected in the Al 2 O 3 films and its impact on the level of surface passivation is demonstrated experimentally. Furthermore, a comparison between the surface passivation achieved for thermal SiO 2 and plasma enhanced chemical vapor deposition SiN x :H films on the same c-Si is presented. The high negative fixed charge density explains the excellent passivation of p-type c-Si by Al 2 O 3 . (cross-disciplinary physics and related areas of science and technology)

  16. First results on the charge collection properties of segmented detectors made with p-type bulk silicon

    International Nuclear Information System (INIS)

    Casse, G.; Allport, P.P.; Bowcock, T.J.V.; Greenall, A.; Hanlon, M.; Jackson, J.N.

    2002-01-01

    Radiation damage of n-type bulk detectors introduces stable defects acting as effective p-type doping and leads to the change of the conductivity type of the silicon substrate (type inversion) after a fluence of a few times 10 13 protons cm -2 . The diode junction after inversion migrates from the original side to the back plane of the detector. The migration of the junction can be prevented using silicon detectors with p-type substrates. Furthermore, the use of n-side readout gives higher charge collection efficiency for segmented devices operated below the full depletion voltage. Large area (∼6.4x6.4 cm 2 ) capacitively coupled 80 μm pitch detectors using polysilicon bias resistors have been fabricated on p-type substrates (n-in-p diode structure). These detectors have been irradiated with 24 GeV/c protons to an integrated fluence of 3x10 14 cm -2 and kept for 7 days at 25 deg. C to reach the broad minimum of the annealing curve. Results are presented on the comparison of their charge collection properties with detectors using p-strip read-out after corresponding dose and annealing

  17. Fabrication of p-type conductivity in SnO{sub 2} thin films through Ga doping

    Energy Technology Data Exchange (ETDEWEB)

    Tsay, Chien-Yie, E-mail: cytsay@fcu.edu.tw; Liang, Shan-Chien

    2015-02-15

    Highlights: • P-type Ga-doped SnO{sub 2} semiconductor films were prepared by sol-gel spin coating. • Optical bandgaps of the SnO{sub 2}:Ga films are narrower than that of the SnO{sub 2} film. • SnO{sub 2}:Ga films exhibited p-type conductivity as Ga doping content higher than 10%. • A p-n heterojunction composed of p-type SnO{sub 2}:Ga and n-type ZnO:Al was fabricated. - Abstract: P-type transparent tin oxide (SnO{sub 2}) based semiconductor thin films were deposited onto alkali-free glass substrates by a sol-gel spin-coating method using gallium (Ga) as acceptor dopant. In this study, we investigated the influence of Ga doping concentration ([Ga]/[Sn] + [Ga] = 0%, 5%, 10%, 15%, and 20%) on the structural, optical and electrical properties of SnO{sub 2} thin films. XRD analysis results showed that dried Ga-doped SnO{sub 2} (SnO{sub 2}:Ga) sol-gel films annealed in oxygen ambient at 520 °C for 1 h exhibited only the tetragonal rutile phase. The average optical transmittance of as-prepared thin film samples was higher than 87.0% in the visible light region; the optical band gap energy slightly decreased from 3.92 eV to 3.83 eV with increases in Ga doping content. Hall effect measurement showed that the nature of conductivity of SnO{sub 2}:Ga thin films changed from n-type to p-type when the Ga doping level was 10%, and when it was at 15%, Ga-doped SnO{sub 2} thin films exhibited the highest mean hole concentration of 1.70 × 10{sup 18} cm{sup -3}. Furthermore, a transparent p-SnO{sub 2}:Ga (Ga doping level of 15%)/n-ZnO:Al (Al doping level of 2%) heterojunction was fabricated on alkali-free glass. The I-V curve measurement for the p-n heterojunction diode showed a typical rectifying characteristic with a forward turn-on voltage of 0.65 V.

  18. The novel transparent sputtered p-type CuO thin films and Ag/p-CuO/n-Si Schottky diode applications

    Directory of Open Access Journals (Sweden)

    A. Tombak

    2015-01-01

    Full Text Available In the current paper, the physical properties and microelectronic parameters of direct current (DC sputtered p-type CuO film and diode have been investigated. The film of CuO as oxide and p-type semiconductor is grown onto glass and n-Si substrates by reactive DC sputtering at 250 °C. After deposition, a post-annealing procedure is applied at various temperatures in ambient. Through this research, several parameters are determined such structural, optical and electrical magnitudes. The thickness of CuO thin films goes from 122 to 254 nm. A (111-oriented cubic crystal structure is revealed by X-ray analysis. The grain size is roughly depending on the post-annealing temperature, it increases with temperature within the 144–285 nm range. The transmittance reaches 80% simultaneously in visible and infrared bands. The optical band gap is varied between 1.99 and 2.52 eV as a result of annealing temperature while the resistivity and the charge carrier mobility decrease with an increase in temperature from 135 to 14 Ω cm and 0.92 to 0.06 cm2/Vs, respectively. The surface of samples is homogenous, bright dots are visible when temperature reaches the highest value. As a diode, Ag/CuO/n-Si exhibits a non-ideal behavior and the ideality factor is about 3.5. By Norde method, the barrier height and the series resistance are extracted and found to be 0.96 V and 86.6 Ω respectively.

  19. Demonstration of molecular beam epitaxy and a semiconducting band structure for I-Mn-V compounds

    International Nuclear Information System (INIS)

    Jungwirth, T.; Novak, V.; Cukr, M.; Zemek, J.; Marti, X.; Horodyska, P.; Nemec, P.; Holy, V.; Maca, F.; Shick, A. B.; Masek, J.; Kuzel, P.; Nemec, I.; Gallagher, B. L.; Campion, R. P.; Foxon, C. T.; Wunderlich, J.

    2011-01-01

    Our ab initio theory calculations predict a semiconducting band structure of I-Mn-V compounds. We demonstrate on LiMnAs that high-quality materials with group-I alkali metals in the crystal structure can be grown by molecular beam epitaxy. Optical measurements on the LiMnAs epilayers are consistent with the theoretical electronic structure. Our calculations also reproduce earlier reports of high antiferromagnetic ordering temperature and predict large, spin-orbit-coupling-induced magnetic anisotropy effects. We propose a strategy for employing antiferromagnetic semiconductors in high-temperature semiconductor spintronics.

  20. Semiconducting, Magnetic or Superconducting Nanoparticles encapsulated in Carbon Shells by RAPET method.

    Directory of Open Access Journals (Sweden)

    Aharon Gedanken

    2008-06-01

    Full Text Available An efficient, solvent-free, environmentally friendly, RAPET (Reactions under Autogenic Pressure at Elevated Temperaturesynthetic approach is discussed for the fabrication of core-shell nanostructures. The semiconducting, magnetic orsuperconducting nanoparticles are encapsulated in a carbon shell. RAPET is a one-step, thermal decomposition reaction ofchemical compound (s followed by the formation of core-shell nanoparticles in a closed stainless steel reactor. Therepresentative examples are discussed, where a variety of nanomaterials are trapped in situ in a carbon shell that offersfascinating properties.

  1. Semiconducting Polymer Photodetectors with Electron and Hole Blocking Layers: High Detectivity in the Near-Infrared

    Directory of Open Access Journals (Sweden)

    Xiong Gong

    2010-07-01

    Full Text Available Sensing from the ultraviolet-visible to the infrared is critical for a variety of industrial and scientific applications. Photodetectors with broad spectral response, from 300 nm to 1,100 nm, were fabricated using a narrow-band gap semiconducting polymer blended with a fullerene derivative. By using both an electron-blocking layer and a hole-blocking layer, the polymer photodetectors, operating at room temperature, exhibited calculated detectivities greater than 1013 cm Hz1/2/W over entire spectral range with linear dynamic range approximately 130 dB. The performance is comparable to or even better than Si photodetectors.

  2. Role of Molecular Weight Distribution on Charge Transport in Semiconducting Polymers

    KAUST Repository

    Himmelberger, Scott

    2014-10-28

    © 2014 American Chemical Society. Model semiconducting polymer blends of well-controlled molecular weight distributions are fabricated and demonstrated to be a simple method to control intermolecular disorder without affecting intramolecular order or degree of aggregation. Mobility measurements exhibit that even small amounts of low molecular weight material are detrimental to charge transport. Trends in charge carrier mobility can be reproduced by a simple analytical model which indicates that carriers have no preference for high or low molecular weight chains and that charge transport is limited by interchain hopping. These results quantify the role of long polymer tie-chains and demonstrate the need for controlled polydispersity for achieving high carrier mobilities.

  3. Semiconductive 3-D haloplumbate framework hybrids with high color rendering index white-light emission.

    Science.gov (United States)

    Wang, Guan-E; Xu, Gang; Wang, Ming-Sheng; Cai, Li-Zhen; Li, Wen-Hua; Guo, Guo-Cong

    2015-12-01

    Single-component white light materials may create great opportunities for novel conventional lighting applications and display systems; however, their reported color rendering index (CRI) values, one of the key parameters for lighting, are less than 90, which does not satisfy the demand of color-critical upmarket applications, such as photography, cinematography, and art galleries. In this work, two semiconductive chloroplumbate (chloride anion of lead(ii)) hybrids, obtained using a new inorganic-organic hybrid strategy, show unprecedented 3-D inorganic framework structures and white-light-emitting properties with high CRI values around 90, one of which shows the highest value to date.

  4. Fabrication and characterization of GaN-based light-emitting diodes without pre-activation of p-type GaN.

    Science.gov (United States)

    Hu, Xiao-Long; Wang, Hong; Zhang, Xi-Chun

    2015-01-01

    We fabricated GaN-based light-emitting diodes (LEDs) without pre-activation of p-type GaN. During the fabrication process, a 100-nm-thick indium tin oxide film was served as the p-type contact layer and annealed at 500°C in N2 ambient for 20 min to increase its transparency as well as to activate the p-type GaN. The electrical measurements showed that the LEDs were featured by a lower forward voltage and higher wall-plug efficiency in comparison with LEDs using pre-activation of p-type GaN. We discussed the mechanism of activation of p-type GaN at 500°C in N2 ambient. Furthermore, x-ray photoemission spectroscopy examinations were carried out to study the improved electrical performances of the LEDs without pre-activation of p-type GaN.

  5. Ab initio density functional theory investigation of electronic properties of semiconducting single-walled carbon nanotube bundles

    Science.gov (United States)

    Moradian, Rostam; Behzad, Somayeh; Azadi, Sam

    2008-09-01

    By using ab initio density functional theory we investigated the structural and electronic properties of semiconducting (7, 0), (8, 0) and (10, 0) carbon nanotube bundles. The energetic and electronic evolutions of nanotubes in the bundling process are also studied. The effects of inter-tube coupling on the electronic dispersions of semiconducting carbon nanotube bundles are demonstrated. Our results show that the inter-tube coupling decreases the energy gap in semiconducting nanotubes. We found that bundles of (7, 0) and (8, 0) carbon nanotubes have metallic feature, while (10, 0) bundle is a semiconductor with an energy gap of 0.22 eV. To clarify our results the band structures of isolated and bundled nanotubes are compared.

  6. Internal photoemission for photovoltaic using p-type Schottky barrier: Band structure dependence and theoretical efficiency limits

    Science.gov (United States)

    Shih, Ko-Han; Chang, Yin-Jung

    2018-01-01

    Solar energy conversion via internal photoemission (IPE) across a planar p-type Schottky junction is quantified for aluminum (Al) and copper (Cu) in the framework of direct transitions with non-constant matrix elements. Transition probabilities and k-resolved group velocities are obtained based on pseudo-wavefunction expansions and realistic band structures using the pseudopotential method. The k-resolved number of direct transitions, hole photocurrent density, quantum yield (QY), and the power conversion efficiency (PCE) under AM1.5G solar irradiance are subsequently calculated and analyzed. For Al, the parabolic and "parallel-band" effect along the U-W-K path significantly enhances the transition rate with final energies of holes mainly within 1.41 eV below the Fermi energy. For Cu, d-state hot holes mostly generated near the upper edge of 3d bands dominate the hole photocurrent and are weekly (strongly) dependent on the barrier height (metal film thickness). Hot holes produced in the 4s band behave just oppositely to their d-state counterparts. Non-constant matrix elements are shown to be necessary for calculations of transitions due to time-harmonic perturbation in Cu. Compared with Cu, Al-based IPE in p-type Schottky shows the highest PCE (QY) up to about 0.2673% (5.2410%) at ΦB = 0.95 eV (0.5 eV) and a film thickness of 11 nm (20 nm). It is predicted that metals with relatively dispersionless d bands (such as Cu) in most cases do not outperform metals with photon-accessible parallel bands (such as Al) in photon energy conversion using a planar p-type Schottky junction.

  7. Modulated charge injection in p-type dye-sensitized solar cells using fluorene-based light absorbers.

    Science.gov (United States)

    Liu, Zonghao; Xiong, Dehua; Xu, Xiaobao; Arooj, Qudsia; Wang, Huan; Yin, Liyuan; Li, Wenhui; Wu, Huaizhi; Zhao, Zhixin; Chen, Wei; Wang, Mingkui; Wang, Feng; Cheng, Yi-Bing; He, Hongshan

    2014-03-12

    In this study, new pull-push arylamine-fluorene based organic dyes zzx-op1, zzx-op2, and zzx-op3 have been designed and synthesized for p-type dye-sensitized solar cells (p-DSCs). In zzx-op1, a di(p-carboxyphenyl)amine (DCPA) was used as an electron donor, a perylenemonoimide (PMID) as an electron acceptor, and a fluorene (FLU) unit with two aliphatic hexyl chains as a π-conjugated linker. In zzx-op2 and zzx-op3, a 3,4-ethylenedioxythiophene (EDOT) and a thiophene were inserted consecutively between PMID and FLU to tune the energy levels of the frontier molecular orbitals of the dyes. The structural modification broadened the spectral coverage from an onset of 700 nm for zzx-op1 to 750 nm for zzx-op3. The electron-rich EDOT and thiophene lifted up the HOMO (highest occupied molecular orbital) levels of zzx-op2 and zzx-op3, making their potential more negative than zzx-op1. When three dyes were employed in p-type DSCs with I(-)/I3(-) as a redox couple and NiO nanoparticles as hole materials, zzx-op1 exhibited impressive energy conversion efficiency of 0.184% with the open-circuit voltage (VOC) of 112 mV and the short-circuit current density (JSC) of 4.36 mA cm(-2) under AM 1.5G condition. Density functional theory calculations, transient photovoltage decay measurements, and electrochemical impedance spectroscopic studies revealed that zzx-op1 sensitized solar cell exhibited much higher charge injection efficiency (90.3%) than zzx-op2 (53.9%) and zzx-op3 (39.0%), indicating a trade-off between spectral broadening and electron injection driving force in p-type DSCs.

  8. Template-based preparation of free-standing semiconducting polymeric nanorod arrays on conductive substrates.

    Science.gov (United States)

    Haberkorn, Niko; Weber, Stefan A L; Berger, Rüdiger; Theato, Patrick

    2010-06-01

    We describe the synthesis and characterization of a cross-linkable siloxane-derivatized tetraphenylbenzidine (DTMS-TPD), which was used for the fabrication of semiconducting highly ordered nanorod arrays on conductive indium tin oxide or Pt-coated substrates. The stepwise process allow fabricating of macroscopic areas of well-ordered free-standing nanorod arrays, which feature a high resistance against organic solvents, semiconducting properties and a good adhesion to the substrate. Thin films of the TPD derivate with good hole-conducting properties could be prepared by cross-linking and covalently attaching to hydroxylated substrates utilizing an initiator-free thermal curing at 160 degrees C. The nanorod arrays composed of cross-linked DTMS-TPD were fabricated by an anodic aluminum oxide (AAO) template approach. Furthermore, the nanorod arrays were investigated by a recently introduced method allowing to probe local conductivity on fragile structures. It revealed that more than 98% of the nanorods exhibit electrical conductance and consequently feature a good electrical contact to the substrate. The prepared nanorod arrays have the potential to find application in the fabrication of multilayered device architectures for building well-ordered bulk-heterojunction solar cells.

  9. Triboelectric charge generation by semiconducting SnO2 film grown by atomic layer deposition

    Science.gov (United States)

    Lee, No Ho; Yoon, Seong Yu; Kim, Dong Ha; Kim, Seong Keun; Choi, Byung Joon

    2017-07-01

    Improving the energy harvesting efficiency of triboelectric generators (TEGs) requires exploring new types of materials that can be used, and understanding their properties. In this study, we have investigated semiconducting SnO2 thin films as friction layers in TEGs, which has not been explored thus far. Thin films of SnO2 with various thicknesses were grown by atomic layer deposition on Si substrates. Either polymer or glass was used as counter friction layers. Vertical contact/separation mode was utilized to evaluate the TEG efficiency. The results indicate that an increase in the SnO2 film thickness from 5 to 25 nm enhances the triboelectric output voltage of the TEG. Insertion of a 400-nm-thick Pt sub-layer between the SnO2 film and Si substrate further increased the output voltage up to 120 V in a 2 cm × 2 cm contact area, while the enhancement was cancelled out by inserting a 10-nm-thick insulating Al2O3 film between SnO2 and Pt films. These results indicate that n-type semiconducting SnO2 films can provide triboelectric charge to counter-friction layers in TEGs.[Figure not available: see fulltext.

  10. XRD- and infrared-probed anisotropic thermal expansion properties of an organic semiconducting single crystal.

    Science.gov (United States)

    Mohanraj, J; Capria, E; Benevoli, L; Perucchi, A; Demitri, N; Fraleoni-Morgera, A

    2018-01-17

    The anisotropic thermal expansion properties of an organic semiconducting single crystal constituted by 4-hydroxycyanobenzene (4HCB) have been probed by XRD in the range 120-300 K. The anisotropic thermal expansion coefficients for the three crystallographic axes and for the crystal volume have been determined. A careful analysis of the crystal structure revealed that the two different H-bonds stemming from the two independent, differently oriented 4HCB molecules composing the unit cell have different rearrangement patterns upon temperature variations, in terms of both bond length and bond angle. Linearly Polarized Mid InfraRed (LP-MIR) measurements carried out in the same temperature range, focused on the O-H bond spectral region, confirm this finding. The same LP-MIR measurements, on the basis of a semi-empirical relation and of geometrical considerations and assumptions, allowed calculation of the -CNH-O- hydrogen bond length along the a and b axes of the crystal. In turn, the so-calculated -CNH-O- bond lengths were used to derive the thermal expansion coefficients along the corresponding crystal axes, as well as the volumetric one, using just the LP-MIR data. Reasonable to good agreement with the same values obtained from XRD measurements was obtained. This proof-of-principle opens interesting perspectives about the possible development of a rapid, low cost and industry-friendly assessment of the thermal expansion properties of organic semiconducting single crystals (OSSCs) involving hydrogen bonds.

  11. Amphiphilic semiconducting polymer as multifunctional nanocarrier for fluorescence/photoacoustic imaging guided chemo-photothermal therapy.

    Science.gov (United States)

    Jiang, Yuyan; Cui, Dong; Fang, Yuan; Zhen, Xu; Upputuri, Paul Kumar; Pramanik, Manojit; Ding, Dan; Pu, Kanyi

    2017-11-01

    Chemo-photothermal nanotheranostics has the advantage of synergistic therapeutic effect, providing opportunities for optimized cancer therapy. However, current chemo-photothermal nanotheranostic systems generally comprise more than three components, encountering the potential issues of unstable nanostructures and unexpected conflicts in optical and biophysical properties among different components. We herein synthesize an amphiphilic semiconducting polymer (PEG-PCB) and utilize it as a multifunctional nanocarrier to simplify chemo-photothermal nanotheranostics. PEG-PCB has a semiconducting backbone that not only serves as the diagnostic component for near-infrared (NIR) fluorescence and photoacoustic (PA) imaging, but also acts as the therapeutic agent for photothermal therapy. In addition, the hydrophobic backbone of PEG-PCB provides strong hydrophobic and π-π interactions with the aromatic anticancer drug such as doxorubicin for drug encapsulation and delivery. Such a trifunctionality of PEG-PCB eventually results in a greatly simplified nanotheranostic system with only two components but multimodal imaging and therapeutic capacities, permitting effective NIR fluorescence/PA imaging guided chemo-photothermal therapy of cancer in living mice. Our study thus provides a molecular engineering approach to integrate essential properties into one polymer for multimodal nanotheranostics. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Effect of fractal silver electrodes on charge collection and light distribution in semiconducting organic polymer films

    Energy Technology Data Exchange (ETDEWEB)

    Chamousis, RL; Chang, LL; Watterson, WJ; Montgomery, RD; Taylor, RP; Moule, AJ; Shaheen, SE; Ilan, B; van de Lagemaat, J; Osterloh, FE

    2014-08-21

    Living organisms use fractal structures to optimize material and energy transport across regions of differing size scales. Here we test the effect of fractal silver electrodes on light distribution and charge collection in organic semiconducting polymer films made of P3HT and PCBM. The semiconducting polymers were deposited onto electrochemically grown fractal silver structures (5000 nm x 500 nm; fractal dimension of 1.71) with PEDOT:PSS as hole-selective interlayer. The fractal silver electrodes appear black due to increased horizontal light scattering, which is shown to improve light absorption in the polymer. According to surface photovoltage spectroscopy, fractal silver electrodes outperform the flat electrodes when the BHJ film thickness is large (>400 nm, 0.4 V photovoltage). Photocurrents of up to 200 microamperes cm(-2) are generated from the bulk heterojunction (BHJ) photoelectrodes under 435 nm LED (10-20 mW cm(-2)) illumination in acetonitrile solution containing 0.005 M ferrocenium hexafluorophosphate as the electron acceptor. The low IPCE values (0.3-0.7%) are due to slow electron transfer to ferrocenium ion and due to shunting along the large metal-polymer interface. Overall, this work provides an initial assessment of the potential of fractal electrodes for organic photovoltaic cells.

  13. Voltage-Controlled Spray Deposition of Multiwalled Carbon Nanotubes on Semiconducting and Insulating Substrates

    Science.gov (United States)

    Maulik, Subhodip; Sarkar, Anirban; Basu, Srismrita; Daniels-Race, Theda

    2018-05-01

    A facile, cost-effective, voltage-controlled, "single-step" method for spray deposition of surfactant-assisted dispersed carbon nanotube (CNT) thin films on semiconducting and insulating substrates has been developed. The fabrication strategy enables direct deposition and adhesion of CNT films on target samples, eliminating the need for substrate surface functionalization with organosilane binder agents or metal layer coatings. Spray coating experiments on four types of sample [bare silicon (Si), microscopy-grade glass samples, silicon dioxide (SiO2), and polymethyl methacrylate (PMMA)] under optimized control parameters produced films with thickness ranging from 40 nm to 6 μm with substantial surface coverage and packing density. These unique deposition results on both semiconducting and insulator target samples suggest potential applications of this technique in CNT thin-film transistors with different gate dielectrics, bendable electronics, and novel CNT-based sensing devices, and bodes well for further investigation into thin-film coatings of various inorganic, organic, and hybrid nanomaterials on different types of substrate.

  14. Tunable Semiconducting Polymer Nanoparticles with INDT-Based Conjugated Polymers for Photoacoustic Molecular Imaging.

    Science.gov (United States)

    Stahl, Thomas; Bofinger, Robin; Lam, Ivan; Fallon, Kealan J; Johnson, Peter; Ogunlade, Olumide; Vassileva, Vessela; Pedley, R Barbara; Beard, Paul C; Hailes, Helen C; Bronstein, Hugo; Tabor, Alethea B

    2017-06-21

    Photoacoustic imaging combines both excellent spatial resolution with high contrast and specificity, without the need for patients to be exposed to ionizing radiation. This makes it ideal for the study of physiological changes occurring during tumorigenesis and cardiovascular disease. In order to fully exploit the potential of this technique, new exogenous contrast agents with strong absorbance in the near-infrared range, good stability and biocompatibility, are required. In this paper, we report the formulation and characterization of a novel series of endogenous contrast agents for photoacoustic imaging in vivo. These contrast agents are based on a recently reported series of indigoid π-conjugated organic semiconductors, coformulated with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, to give semiconducting polymer nanoparticles of about 150 nm diameter. These nanoparticles exhibited excellent absorption in the near-infrared region, with good photoacoustic signal generation efficiencies, high photostability, and extinction coefficients of up to three times higher than those previously reported. The absorption maximum is conveniently located in the spectral region of low absorption of chromophores within human tissue. Using the most promising semiconducting polymer nanoparticle, we have demonstrated wavelength-dependent differential contrast between vasculature and the nanoparticles, which can be used to unambiguously discriminate the presence of the contrast agent in vivo.

  15. Structure-Property Relationships of Semiconducting Polymers for Flexible and Durable Polymer Field-Effect Transistors.

    Science.gov (United States)

    Kim, Min Je; Jung, A-Ra; Lee, Myeongjae; Kim, Dongjin; Ro, Suhee; Jin, Seon-Mi; Nguyen, Hieu Dinh; Yang, Jeehye; Lee, Kyung-Koo; Lee, Eunji; Kang, Moon Sung; Kim, Hyunjung; Choi, Jong-Ho; Kim, BongSoo; Cho, Jeong Ho

    2017-11-22

    We report high-performance top-gate bottom-contact flexible polymer field-effect transistors (FETs) fabricated by flow-coating diketopyrrolopyrrole (DPP)-based and naphthalene diimide (NDI)-based polymers (P(DPP2DT-T2), P(DPP2DT-TT), P(DPP2DT-DTT), P(NDI2OD-T2), P(NDI2OD-F2T2), and P(NDI2OD-Se2)) as semiconducting channel materials. All of the polymers displayed good FET characteristics with on/off current ratios exceeding 10 7 . The highest hole mobility of 1.51 cm 2 V -1 s -1 and the highest electron mobility of 0.85 cm 2 V -1 s -1 were obtained from the P(DPP2DT-T2) and P(NDI2OD-Se2) polymer FETs, respectively. The impacts of the polymer structures on the FET performance are well-explained by the interplay between the crystallinity, the tendency of the polymer backbone to adopt an edge-on orientation, and the interconnectivity of polymer fibrils in the film state. Additionally, we demonstrated that all of the flexible polymer-based FETs were highly resistant to tensile stress, with negligible changes in their carrier mobilities and on/off ratios after a bending test. Conclusively, these high-performance, flexible, and durable FETs demonstrate the potential of semiconducting conjugated polymers for use in flexible electronic applications.

  16. Scintillation properties of semiconducting {sup 6}LiInSe{sub 2} crystals to ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Wiggins, Brenden [Y-12 National Security Complex, Oak Ridge, TN (United States); Vanderbilt University, Nashville, TN (United States); Groza, Michael; Tupitsyn, Eugene [Fisk University, Nashville, TN (United States); Lukosi, Eric [University of Tennessee, Knoxville, TN (United States); Stassun, Keivan; Burger, Arnold [Vanderbilt University, Nashville, TN (United States); Fisk University, Nashville, TN (United States); Stowe, Ashley [Y-12 National Security Complex, Oak Ridge, TN (United States); Vanderbilt University, Nashville, TN (United States); University of Tennessee, Knoxville, TN (United States)

    2015-11-21

    {sup 6}LiInSe{sub 2} has gained attention recently as a semiconducting thermal neutron detector. As presented herein, the chalcogenide compound semiconductor also detects incident neutrons via scintillation, making {sup 6}LiInSe{sub 2} the only lithium containing semiconductor to respond to neutrons via both detection mechanisms. Both yellow and red crystals, which appear in the literature, were investigated. Only the yellow crystal responded favorably to ionizing radiation, similar to the semiconducting operation utilizing electrodes. The obtained light yield for yellow crystals is 4400 photons/MeV, referenced to Bi{sub 4}Ge{sub 3}O{sub 12} (BGO).The estimated thermal neutron light yield was 21,000 photons/thermal neutron. The two measured decay time components were found to be 31±1 ns (49%) and 143±9 ns (51%).This crystal provides efficient, robust detection of neutrons via scintillation with respectable light yield and rapid response, enabling its use for a broad array of neutron detection applications.

  17. Synthesis and morphological modification of semiconducting Mg(Zn)Al(Ga)–LDH/ITO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Valente, Jaime S., E-mail: jsanchez@imp.mx [Instituto Mexicano del Petróleo, Eje Central # 152, 07730 México D.F. (Mexico); López-Salinas, Esteban [Instituto Mexicano del Petróleo, Eje Central # 152, 07730 México D.F. (Mexico); Prince, Julia [Universidad Anáhuac México Norte, Av. Universidad Anáhuac # 46, Huixquilucan, Edo. de México 52786 (Mexico); González, Ignacio; Acevedo-Peña, Prospero [Universidad Autónoma Metropolitana-Iztapalapa, Departamento de Química, Apdo. Postal 55-534, 09340 México D.F. (Mexico); Ángel, Paz del [Instituto Mexicano del Petróleo, Eje Central # 152, 07730 México D.F. (Mexico)

    2014-09-15

    Layered double hydroxide (LDH) thin films with different chemical compositions (MgZnAl, MgZnGa, MgGaAl) and varying thicknesses were easily prepared by sol–gel method followed by dip-coating. Films were chemically uniform, transparent and well adhered to a conductive indium tin oxide (ITO) substrate. Structure, chemical composition and morphology of the thin films were characterized by XRD-GADDS, SEM-EDS and AFM. Additionally, the semiconducting properties of all the prepared films were studied through the Mott–Schottky relationship; such properties were closely related to the chemical compositions of the film. The films were characterized after electrochemical treatment and important modifications regarding surface morphology, particle and crystal sizes were observed. An in-depth study was conducted in order to investigate the effect of several different electrochemical treatments on the morphology, particle size distribution and crystal size of LDH thin films. Upon electrochemical treatment, the films' surface became smooth and the particles forming the films were transformed from flaky open LDH platelets to uniformly distributed close-packed LDH nanoparticles. - Highlights: • Semiconducting Mg(Zn)Al(Ga)–LDH/ITO thin films prepared by sol–gel. • LDH thin films show a turbostratic morphology made up of porous flakes. • Electrochemical treatments change the flaky structure into a nanoparticle array.

  18. Influence of nanosized inclusions on the room temperature thermoelectrical properties of a p-type bismuth–tellurium–antimony alloy

    International Nuclear Information System (INIS)

    Bernard-Granger, Guillaume; Addad, Ahmed; Navone, Christelle; Soulier, Mathieu; Simon, Julia; Szkutnik, Pierre-David

    2012-01-01

    Transmission electron microscopy observations and thermoelectrical property measurements (electrical conductivity, Seebeck coefficient and thermal conductivity) at room temperature have been completed on two fully dense polycrystalline p-type bismuth–tellurium–antimony alloy samples. It is shown that the presence of antimony oxide-based nanosized inclusions (controlled as to volume fraction and size distribution), homogeneously dispersed in the surrounding matrix leads to a dimensionless figure of merit (ZT) of ∼1.3 at room temperature. For comparison, when such inclusions are missing the ZT value is only 0.6.

  19. Prediction and theoretical characterization of p-type organic semiconductor crystals for field-effect transistor applications.

    Science.gov (United States)

    Atahan-Evrenk, Sule; Aspuru-Guzik, Alán

    2014-01-01

    The theoretical prediction and characterization of the solid-state structure of organic semiconductors has tremendous potential for the discovery of new high performance materials. To date, the theoretical analysis mostly relied on the availability of crystal structures obtained through X-ray diffraction. However, the theoretical prediction of the crystal structures of organic semiconductor molecules remains a challenge. This review highlights some of the recent advances in the determination of structure-property relationships of the known organic semiconductor single-crystals and summarizes a few available studies on the prediction of the crystal structures of p-type organic semiconductors for transistor applications.

  20. Surface accumulation conduction controlled sensing characteristic of p-type CuO nanorods induced by oxygen adsorption

    International Nuclear Information System (INIS)

    Wang, C; Fu, X Q; Xue, X Y; Wang, Y G; Wang, T H

    2007-01-01

    P-type CuO nanorods were synthesized by a hydrothermal method and the ethanol-sensing properties of sensors based on CuO were investigated. The sensor resistance increased when it was exposed to ethanol and decreased in the air, which is contrary to the case for sensors realized from n-type semiconductor. The resistance of the CuO-based sensor was about 2 kΩ in air and 6 kΩ in ethanol vapour with concentration of 2000 ppm. Such a sensing property is attributed to surface accumulation conduction. Sensors based on CuO nanorods have potential applications in detecting ethanol in low concentration

  1. Primary defect transformations in high-resistivity p-type silicon irradiated with electrons at cryogenic temperatures

    CERN Document Server

    Makarenko, L F; Korshunov, F P; Murin, L I; Moll, M

    2009-01-01

    It has been revealed that self-interstitials formed under low intensity electron irradiationin high resistivity p-type silicon can be retained frozen up to room temperature. Low thermal mobility of the self-interstitials suggests that Frenkelpair sinsilicon can be stable at temperatures of about or higher than 100K. A broad DLTS peak with activation energy of 0.14–0.17eV can be identified as related to Frenkel pairs. This peak anneals out at temperatures of 120 140K. Experimental evidences are presented that be coming more mobile under forwardcurrent injection the self-interstitials change their charge state to a less positive one.

  2. Hole polaron-polaron interaction in transition metal oxides and its limit to p-type doping

    Science.gov (United States)

    Chen, Shiyou; Wang, Lin-Wang

    2014-03-01

    Traditionally the origin of the poor p-type conductivity in some transition metal oxides (TMOs) was attributed to the limited hole concentration: the charge-compensating donor defects, such as oxygen vacancies and cation interstitials, can form spontaneously as the Fermi energy shifts down to near the valence band maximum. Besides the thermodynamic limit to the hole concentration, the limit to the hole mobility can be another possible reason, e.g., the hole carrier can form self-trapped polarons with very low carrier mobility. Although isolated hole polarons had been found in some TMOs, the polaron-polaron interaction is not well-studied. Here we show that in TMOs such as TiO2 and V2O5, the hole polarons prefer to bind with each other to form bipolarons, which are more stable than free hole carriers or separated polarons. This pushes the hole states upward into the conduction band and traps the holes. The rise of the Fermi energy suppresses the spontaneous formation of the charge-compensating donor defects, so the conventional mechanism becomes ineffective. Since it can happen in the impurity-free TMO lattices, independent of any extrinsic dopant, it acts as an intrinsic and general limit to the p-type conductivity in these TMOs. This material is based upon work performed by the JCAP, a US DOE Energy Innovation Hub, the NSFC (No. 61106087 and 91233121) and special funds for major state basic research (No. 2012CB921401).

  3. Search for Pauli exclusion principle violating atomic transitions and electron decay with a p-type point contact germanium detector

    Energy Technology Data Exchange (ETDEWEB)

    Abgrall, N.; Bradley, A.W.; Chan, Y.D.; Mertens, S.; Poon, A.W.P. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Arnquist, I.J.; Hoppe, E.W.; Kouzes, R.T.; LaFerriere, B.D.; Orrell, J.L. [Pacific Northwest National Laboratory, Richland, WA (United States); Avignone, F.T. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of South Carolina, Department of Physics and Astronomy, Columbia, SC (United States); Barabash, A.S.; Konovalov, S.I.; Yumatov, V. [National Research Center ' ' Kurchatov Institute' ' Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Bertrand, F.E.; Galindo-Uribarri, A.; Radford, D.C.; Varner, R.L.; White, B.R.; Yu, C.H. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Brudanin, V.; Shirchenko, M.; Vasilyev, S.; Yakushev, E.; Zhitnikov, I. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Busch, M. [Duke University, Department of Physics, Durham, NC (United States); Triangle Universities Nuclear Laboratory, Durham, NC (United States); Buuck, M.; Cuesta, C.; Detwiler, J.A.; Gruszko, J.; Guinn, I.S.; Leon, J.; Robertson, R.G.H. [University of Washington, Department of Physics, Center for Experimental Nuclear Physics and Astrophysics, Seattle, WA (United States); Caldwell, A.S.; Christofferson, C.D.; Dunagan, C.; Howard, S.; Suriano, A.M. [South Dakota School of Mines and Technology, Rapid City, SD (United States); Chu, P.H.; Elliott, S.R.; Goett, J.; Massarczyk, R.; Rielage, K. [Los Alamos National Laboratory, Los Alamos, NM (United States); Efremenko, Yu. [University of Tennessee, Department of Physics and Astronomy, Knoxville, TN (United States); Ejiri, H. [Osaka University, Research Center for Nuclear Physics, Ibaraki, Osaka (Japan); Finnerty, P.S.; Gilliss, T.; Giovanetti, G.K.; Henning, R.; Howe, M.A.; MacMullin, J.; Meijer, S.J.; O' Shaughnessy, C.; Rager, J.; Shanks, B.; Trimble, J.E.; Vorren, K.; Xu, W. [Triangle Universities Nuclear Laboratory, Durham, NC (United States); University of North Carolina, Department of Physics and Astronomy, Chapel Hill, NC (United States); Green, M.P. [North Carolina State University, Department of Physics, Raleigh, NC (United States); Oak Ridge National Laboratory, Oak Ridge, TN (United States); Triangle Universities Nuclear Laboratory, Durham, NC (United States); Guiseppe, V.E.; Tedeschi, D.; Wiseman, C. [University of South Carolina, Department of Physics and Astronomy, Columbia, SC (United States); Jasinski, B.R. [University of South Dakota, Department of Physics, Vermillion, SD (United States); Keeter, K.J. [Black Hills State University, Department of Physics, Spearfish, SD (United States); Kidd, M.F. [Tennessee Tech University, Cookeville, TN (United States); Martin, R.D. [Queen' s University, Department of Physics, Engineering Physics and Astronomy, Kingston, ON (Canada); Romero-Romero, E. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of Tennessee, Department of Physics and Astronomy, Knoxville, TN (United States); Vetter, K. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); University of California, Department of Nuclear Engineering, Berkeley, CA (United States); Wilkerson, J.F. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Triangle Universities Nuclear Laboratory, Durham, NC (United States); University of North Carolina, Department of Physics and Astronomy, Chapel Hill, NC (United States)

    2016-11-15

    A search for Pauli-exclusion-principle-violating K{sub α} electron transitions was performed using 89.5 kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of 5.8 x 10{sup 30} s at 90% C.L. was set by looking for a peak at 10.6 keV resulting from the X-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of 6.8 x 10{sup 30} s at 90% C.L. It is estimated that the Majorana Demonstrator, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of {sup 76}Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation. (orig.)

  4. Silicon heterojunction solar cells with novel fluorinated n-type nanocrystalline silicon oxide emitters on p-type crystalline silicon

    Science.gov (United States)

    Dhar, Sukanta; Mandal, Sourav; Das, Gourab; Mukhopadhyay, Sumita; Pratim Ray, Partha; Banerjee, Chandan; Barua, Asok Kumar

    2015-08-01

    A novel fluorinated phosphorus doped silicon oxide based nanocrystalline material have been used to prepare heterojunction solar cells on flat p-type crystalline silicon (c-Si) Czochralski (CZ) wafers. The n-type nc-SiO:F:H material were deposited by radio frequency plasma enhanced chemical vapor deposition. Deposited films were characterized in detail by using atomic force microscopy (AFM), high resolution transmission electron microscopy (HRTEM), Raman, fourier transform infrared spectroscopy (FTIR) and optoelectronics properties have been studied using temperature dependent conductivity measurement, Ellipsometry, UV-vis spectrum analysis etc. It is observed that the cell fabricated with fluorinated silicon oxide emitter showing higher initial efficiency (η = 15.64%, Jsc = 32.10 mA/cm2, Voc = 0.630 V, FF = 0.77) for 1 cm2 cell area compare to conventional n-a-Si:H emitter (14.73%) on flat c-Si wafer. These results indicate that n type nc-SiO:F:H material is a promising candidate for heterojunction solar cell on p-type crystalline wafers. The high Jsc value is associated with excellent quantum efficiencies at short wavelengths (<500 nm).

  5. High performance p-type segmented leg of misfit-layered cobaltite and half-Heusler alloy

    International Nuclear Information System (INIS)

    Hung, Le Thanh; Van Nong, Ngo; Snyder, G. Jeffrey; Viet, Man Hoang; Balke, Benjamin; Han, Li; Stamate, Eugen; Linderoth, Søren; Pryds, Nini

    2015-01-01

    Highlights: • p-type segmented leg of oxide and half-Heusler was for the first time demonstrated. • The maximum conversion efficiency reached a value of about 5%. • The results are among the highest reported values so far for oxide-based legs. • Oxide-based segmented leg is very promising for generating electricity. - Abstract: In this study, a segmented p-type leg of doped misfit-layered cobaltite Ca 2.8 Lu 0.15 Ag 0.05 Co 4 O 9+δ and half-Heusler Ti 0.3 Zr 0.35 Hf 0.35 CoSb 0.8 Sn 0.2 alloy was fabricated and characterized. The thermoelectric properties of single components, segmented leg, and the electrical contact resistance of the joint part were measured as a function of temperature. The output power generation characteristics of segmented legs were characterized in air under various temperature gradients, ΔT, with the hot side temperature up to 1153 K. At ΔT ≈ 756 K, the maximum conversion efficiency reached a value of ∼5%, which is about 65% of that expected from the materials without parasitic losses. The long-term stability investigation for two weeks at the hot and cold side temperatures of 1153/397 K shows that the segmented leg has good durability as a result of stable and low electrical resistance contacts

  6. Exploring the doping effects of Ag in p-type PbSe compounds with enhanced thermoelectric performance

    Science.gov (United States)

    Wang, Shanyu; Zheng, Gang; Luo, Tingting; She, Xiaoyu; Li, Han; Tang, Xinfeng

    2011-11-01

    In this study, we prepared a series of Ag-doped PbSe bulk materials by a melting-quenching process combined with a subsequent spark plasma sintering process, and systematically investigated the doping effects of Ag on the thermoelectric properties. Ag substitution in the Pb site does not introduce resonant levels near the valence band edge or detectable change in the density of state in the vicinity of the Fermi level, but moves the Fermi level down and increases the carrier concentration to a maximum value of ~4.7 × 1019 cm-3 which is still insufficient for heavily doped PbSe compounds. Nonetheless, the non-monotonic variation in carrier concentration with increasing Ag content indicates that Ag doping reaches the solution limit at ~1.0% and the excessive Ag presumably acts as donors in the materials. Moreover, the large energy gap of the PbSe-based material wipes off significant 'roll-over' in the Seebeck coefficient at elevated temperatures which gives rise to high power factors, being comparable to p-type Te analogues. Consequently, the maximum ZT reaches ~1.0 for the 1.5% Ag-doped samples with optimized carrier density, which is ~70% improvement in comparison with an undoped sample and also superior to the commercialized p-type PbTe materials.

  7. Exploring the doping effects of Ag in p-type PbSe compounds with enhanced thermoelectric performance

    International Nuclear Information System (INIS)

    Wang Shanyu; Zheng Gang; Luo Tingting; She Xiaoyu; Li Han; Tang Xinfeng

    2011-01-01

    In this study, we prepared a series of Ag-doped PbSe bulk materials by a melting-quenching process combined with a subsequent spark plasma sintering process, and systematically investigated the doping effects of Ag on the thermoelectric properties. Ag substitution in the Pb site does not introduce resonant levels near the valence band edge or detectable change in the density of state in the vicinity of the Fermi level, but moves the Fermi level down and increases the carrier concentration to a maximum value of ∼4.7 × 10 19 cm -3 which is still insufficient for heavily doped PbSe compounds. Nonetheless, the non-monotonic variation in carrier concentration with increasing Ag content indicates that Ag doping reaches the solution limit at ∼1.0% and the excessive Ag presumably acts as donors in the materials. Moreover, the large energy gap of the PbSe-based material wipes off significant 'roll-over' in the Seebeck coefficient at elevated temperatures which gives rise to high power factors, being comparable to p-type Te analogues. Consequently, the maximum ZT reaches ∼1.0 for the 1.5% Ag-doped samples with optimized carrier density, which is ∼70% improvement in comparison with an undoped sample and also superior to the commercialized p-type PbTe materials.

  8. P-type conduction in Mg-doped GaN treated with low-energy electron beam irradiation (LEEBI)

    International Nuclear Information System (INIS)

    Amano, Hiroshi; Kito, Masahiro; Hiramatsu, Kazumasa

    1989-01-01

    Distinct p-type conduction is realized with Mg-doped GaN by the low-energy electron-beam irradiation (LEEBI) treatment, and the properties of the GaN p-n junction LED are reported for the first time. It was found that the LEEBI treatment drastically lowers the resistivity and remarkably enhances the PL efficiency of MOVPE-grown Mg-doped GaN. The Hall effect measurement of this Mg-doped GaN treated with LEEBI at room temperature showed that the hole concentration is ∼2·10 16 cm -3 , the hole mobility is ∼8 cm 2 /V·s and the resistivity is ∼35Ω· cm. The p-n junction LED using Mg-doped GaN treated with LEEBI as the p-type material showed strong near-band-edge emission due to the hole injection from the p-layer to the n-layer at room temperature. (author)

  9. P-n junction diodes with polarization induced p-type graded InxGa1-xN layer

    Science.gov (United States)

    Enatsu, Yuuki; Gupta, Chirag; Keller, Stacia; Nakamura, Shuji; Mishra, Umesh K.

    2017-10-01

    In this study, p-n junction diodes with polarization induced p-type layer are demonstrated on Ga polar (0001) bulk GaN substrates. A quasi-p-type region is obtained by linearly grading the indium composition in un-doped InxGa1-xN layers from 0% to 5%, taking advantage of the piezoelectric and spontaneous polarization fields which exist in group III-nitride heterostructures grown in the typical (0001) or c-direction. The un-doped graded InxGa1-xN layers needed to be capped with a thin Mg-doped InxGa1-xN layer to make good ohmic contacts and to reduce the on-resistance of the p-n diodes. The Pol-p-n junction diodes exhibited similar characteristics compared to reference samples with traditional p-GaN:Mg layers. A rise in breakdown voltage from 30 to 110 V was observed when the thickness of the graded InGaN layer was increased from 100 to 600 nm at the same grade composition.

  10. Comparative studies on p-type CuI grown on glass and copper substrate by SILAR method

    Energy Technology Data Exchange (ETDEWEB)

    Dhere, Sunetra L.; Latthe, Sanjay S. [Air Glass Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004, Maharashtra (India); Kappenstein, Charles [University of Poitiers, Laboratory of Catalysis in Organic Chemistry, LA CCO, UMR CNRS 6503, Poitiers-86000 (France); Mukherjee, S.K. [Fuel Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai - 400085, Maharashtra India (India); Rao, A. Venkateswara, E-mail: avrao2012@gmail.com [Air Glass Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004, Maharashtra (India)

    2010-04-01

    Depending upon the method of synthesis and the nature of substrate surface, there is variation in the physico-chemical properties of the material. Cuprous iodide films are deposited at room temperature on the glass and copper substrates by a simple SILAR method and the obtained results are compared. The p-type material with optical band gap 2.88 eV is found to be possessing face-centered cubic crystal structure with lattice parameter 6.134 A. We observed irregular particles for the CuI film on the glass substrate while patterned arrays of micro-rods with cabbage like tips on copper substrate, for the same preparative conditions. Also, the material deposited on copper is showing superhydrophobic nature (contact angle {approx}156{sup o}) while that on glass it is hydrophilic (contact angle {approx}88{sup o}). We have characterized the thin films by X-ray diffraction, scanning electron microscopy, surface roughness and contact angle measurement, thermoelectric power measurement and optical studies. This hydrophobic, p-type material with wide band gap will be helpful in the development of optoelectronic devices.

  11. Comparative studies on p-type CuI grown on glass and copper substrate by SILAR method

    International Nuclear Information System (INIS)

    Dhere, Sunetra L.; Latthe, Sanjay S.; Kappenstein, Charles; Mukherjee, S.K.; Rao, A. Venkateswara

    2010-01-01

    Depending upon the method of synthesis and the nature of substrate surface, there is variation in the physico-chemical properties of the material. Cuprous iodide films are deposited at room temperature on the glass and copper substrates by a simple SILAR method and the obtained results are compared. The p-type material with optical band gap 2.88 eV is found to be possessing face-centered cubic crystal structure with lattice parameter 6.134 A. We observed irregular particles for the CuI film on the glass substrate while patterned arrays of micro-rods with cabbage like tips on copper substrate, for the same preparative conditions. Also, the material deposited on copper is showing superhydrophobic nature (contact angle ∼156 o ) while that on glass it is hydrophilic (contact angle ∼88 o ). We have characterized the thin films by X-ray diffraction, scanning electron microscopy, surface roughness and contact angle measurement, thermoelectric power measurement and optical studies. This hydrophobic, p-type material with wide band gap will be helpful in the development of optoelectronic devices.

  12. Preparation and thermoelectric properties of p-Type PrzFe4-xCoxSb12 skutterudites

    International Nuclear Information System (INIS)

    Shin, Dong-Kil; Kim, Il-Ho

    2014-01-01

    p-Type Pr z Fe 4-x Co x Sb 12 (z = 0.8, 1.0 and x = 0, 0.5, 1.0) skutterudites were synthesized by encapsulated melting and annealing and were consolidated with hot pressing. The effects of Pr filling and Co substitution for Fe (charge compensation) on the transport and the thermoelectric properties were examined. A few secondary phases, such as Sb and FeSb 2 , were formed together with the skutterudite phase, but the formation was suppressed with increasing Pr and Co contents. We confirmed that Pr filled in the voids and that Co was substituted for Fe in all specimens because the lattice constant increased with increasing Pr content and decreased with increasing Co content. The electrical conductivity decreased slightly with increasing temperature, showing degenerate semiconductor characteristics. The Hall and the Seebeck coefficients showed positive signs, indicating that the major carriers were holes (p-type conduction). The electrical conductivity and the thermal conductivity were decreased due to a decrease in the carrier concentration with increasing Pr and Co contents. As a result, the dimensionless figure of merit, ZT, was improved by Pr filling and Co substitution, and a maximum ZT = 0.89 was obtained at 723 K for Pr 0.8 Fe 3 CoSb 12 .

  13. Structural studies of P-type ATPase–ligand complexes using an X-ray free-electron laser

    Directory of Open Access Journals (Sweden)

    Maike Bublitz

    2015-07-01

    Full Text Available Membrane proteins are key players in biological systems, mediating signalling events and the specific transport of e.g. ions and metabolites. Consequently, membrane proteins are targeted by a large number of currently approved drugs. Understanding their functions and molecular mechanisms is greatly dependent on structural information, not least on complexes with functionally or medically important ligands. Structure determination, however, is hampered by the difficulty of obtaining well diffracting, macroscopic crystals. Here, the feasibility of X-ray free-electron-laser-based serial femtosecond crystallography (SFX for the structure determination of membrane protein–ligand complexes using microcrystals of various native-source and recombinant P-type ATPase complexes is demonstrated. The data reveal the binding sites of a variety of ligands, including lipids and inhibitors such as the hallmark P-type ATPase inhibitor orthovanadate. By analyzing the resolution dependence of ligand densities and overall model qualities, SFX data quality metrics as well as suitable refinement procedures are discussed. Even at relatively low resolution and multiplicity, the identification of ligands can be demonstrated. This makes SFX a useful tool for ligand screening and thus for unravelling the molecular mechanisms of biologically active proteins.

  14. Structural studies of P-type ATPase–ligand complexes using an X-ray free-electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Bublitz, Maike; Nass, Karol; Drachmann, Nikolaj D.; Markvardsen, Anders J.; Gutmann, Matthias J.; Barends, Thomas R. M.; Mattle, Daniel; Shoeman, Robert L.; Doak, R. Bruce; Boutet, Sébastien; Messerschmidt, Marc; Seibert, Marvin M.; Williams, Garth J.; Foucar, Lutz; Reinhard, Linda; Sitsel, Oleg; Gregersen, Jonas L.; Clausen, Johannes D.; Boesen, Thomas; Gotfryd, Kamil; Wang, Kai-Tuo; Olesen, Claus; Møller, Jesper V.; Nissen, Poul; Schlichting, Ilme

    2015-06-11

    Membrane proteins are key players in biological systems, mediating signalling events and the specific transport ofe.g.ions and metabolites. Consequently, membrane proteins are targeted by a large number of currently approved drugs. Understanding their functions and molecular mechanisms is greatly dependent on structural information, not least on complexes with functionally or medically important ligands. Structure determination, however, is hampered by the difficulty of obtaining well diffracting, macroscopic crystals. Here, the feasibility of X-ray free-electron-laser-based serial femtosecond crystallography (SFX) for the structure determination of membrane protein–ligand complexes using microcrystals of various native-source and recombinant P-type ATPase complexes is demonstrated. The data reveal the binding sites of a variety of ligands, including lipids and inhibitors such as the hallmark P-type ATPase inhibitor orthovanadate. By analyzing the resolution dependence of ligand densities and overall model qualities, SFX data quality metrics as well as suitable refinement procedures are discussed. Even at relatively low resolution and multiplicity, the identification of ligands can be demonstrated. This makes SFX a useful tool for ligand screening and thus for unravelling the molecular mechanisms of biologically active proteins.

  15. Magnetism in the p-type Monolayer II-VI semiconductors SrS and SrSe

    Science.gov (United States)

    Lin, Heng-Fu; Lau, Woon-Ming; Zhao, Jijun

    2017-01-01

    Using density functional theory calculations, we study the electronic and magnetic properties of the p-type monolayer II-VI semiconductors SrX (X = S,Se). The pristine SrS and SrSe monolayers are large band gap semiconductor with a very flat band in the top valence band. Upon injecting hole uniformly, ferromagnetism emerges in those system in a large range of hole density. By varying hole density, the systems also show complicated phases transition among nonmagnetic semiconductor, half metal, magnetic semiconductor, and nonmagnetic metal. Furthermore, after introducing p-type dopants in SrS and SrSe via substitutionary inserting P (or As) dopants at the S (or Se) sites, local magnetic moments are formed around the substitutional sites. The local magnetic moments are stable with the ferromagnetic order with appreciable Curie temperature. The ferromagnetism originates from the instability of the electronic states in SrS and SrSe with the large density of states at the valence band edge, which demonstrates a useful strategy for realizing the ferromagnetism in the two dimensional semiconductors. PMID:28378761

  16. P-stop isolation study of irradiated n-in-p type silicon strip sensors for harsh radiation environment

    CERN Document Server

    AUTHOR|(CDS)2084505

    2015-01-01

    In order to determine the most radiation hard silicon sensors for the CMS Experiment after the Phase II Upgrade in 2023 a comprehensive study of silicon sensors after a fluence of up to $1.5\\times10^{15} n_{eq}/cm^{2}$ corresponding to $3000 fb^{-1}$ after the HL-LHC era has been carried out. The results led to the decision that the future Outer Tracker (20~cm${<}R{<}$110~cm) of CMS will consist of n-in-p type sensors. This technology is more radiation hard but also the manufacturing is more challenging compared to p-in-n type sensors due to additional process steps in order to suppress the accumulation of electrons between the readout strips. One possible isolation technique of adjacent strips is the p-stop structure which is a p-type material implantation with a certain pattern for each individual strip. However, electrical breakdown and charge collection studies indicate that the process parameters of the p-stop structure have to be carefully calibrated in order to achieve a sufficient strip isolatio...

  17. Optimization of KOH etching parameters for quantitative defect recognition in n- and p-type doped SiC

    Science.gov (United States)

    Sakwe, S. A.; Müller, R.; Wellmann, P. J.

    2006-04-01

    We have developed a KOH-based defect etching procedure for silicon carbide (SiC), which comprises in situ temperature measurement and control of melt composition. As benefit for the first time reproducible etching conditions were established (calibration plot, etching rate versus temperature and time); the etching procedure is time independent, i.e. no altering in KOH melt composition takes place, and absolute melt temperature values can be set. The paper describes this advanced KOH etching furnace, including the development of a new temperature sensor resistant to molten KOH. We present updated, absolute KOH etching parameters of n-type SiC and new absolute KOH etching parameters for low and highly p-type doped SiC, which are used for quantitative defect analysis. As best defect etching recipes we found T=530 °C/5 min (activation energy: 16.4 kcal/mol) and T=500 °C/5 min (activation energy: 13.5 kcal/mol) for n-type and p-type SiC, respectively.

  18. Fundamental piezo-Hall coefficients of single crystal p-type 3C-SiC for arbitrary crystallographic orientation

    Science.gov (United States)

    Qamar, Afzaal; Dao, Dzung Viet; Phan, Hoang-Phuong; Dinh, Toan; Dimitrijev, Sima

    2016-08-01

    Piezo-Hall effect in a single crystal p-type 3C-SiC, grown by LPCVD process, has been characterized for various crystallographic orientations. The quantified values of the piezo-Hall effect in heavily doped p-type 3C-SiC(100) and 3C-SiC(111) for different crystallographic orientations were used to obtain the fundamental piezo-Hall coefficients, P 12 = ( 5.3 ± 0.4 ) × 10 - 11 Pa - 1 , P 11 = ( - 2.6 ± 0.6 ) × 10 - 11 Pa - 1 , and P 44 = ( 11.42 ± 0.6 ) × 10 - 11 Pa - 1 . Unlike the piezoresistive effect, the piezo-Hall effect for (100) and (111) planes is found to be independent of the angle of rotation of the device within the crystal plane. The values of fundamental piezo-Hall coefficients obtained in this study can be used to predict the piezo-Hall coefficients in any crystal orientation which is very important for designing of 3C-SiC Hall sensors to minimize the piezo-Hall effect for stable magnetic field sensitivity.

  19. Characterization of a heavy metal translocating P-type ATPase gene from an environmental heavy metal resistance Enterobacter sp. isolate.

    Science.gov (United States)

    Chien, Chih-Ching; Huang, Chia-Hsuan; Lin, Yi-Wei

    2013-03-01

    Heavy metals are common contaminants found in polluted areas. We have identified a heavy metal translocating P-type ATPase gene (hmtp) via fosmid library and in vitro transposon mutagenesis from an Enterobacter sp. isolate. This gene is believed to participate in the bacterium's heavy metal resistance traits. The complete gene was identified, cloned, and expressed in a suitable Escherichia coli host cell. E. coli W3110, RW3110 (zntA::Km), GG48 (ΔzitB::Cm zntA::Km), and GG51 (ΔzitB::Cm) were used to study the possible effects of this gene for heavy metal (cadmium and zinc in particular) resistance. Among the E. coli strains tested, RW3110 and GG48 showed more sensitivity to cadmium and zinc compared to the wild-type E. coli W3110 and strain GG51. Therefore, strains RW3110 and GG48 were chosen for the reference hosts for further evaluation of the gene's effect. The results showed that expression of this heavy metal translocating P-type ATPase gene could increase the ability for zinc and cadmium resistance in the tested microorganisms.

  20. Efficiency for close geometries and extended sources of a p-type germanium detector with low-energy sensitivity

    International Nuclear Information System (INIS)

    Keyser, R.M.; Twomey, T.R.

    2007-01-01

    Typically, germanium detectors designed to have good sensitivity to low-energy photons and good efficiency at high energies are constructed from n-type crystals with a boron-implanted outer contact. These detectors usually exhibit inferior resolution and peak shape compared to ones made from p-type crystals. To overcome the resolution and peak-shape deficiencies, a new method of construction of a germanium detector element was developed. This has resulted in a gamma-ray detector with high sensitivity to photon energies from 14 keV to 2 MeV, while maintaining good resolution and peak shape over this energy range. Efficiency measurements, done according to the draft IEEE 325-2004 standard, show efficiencies typical of a GMX or n-type detector at low energies. The detectors are of large diameter suitable for counting extended samples such as filter papers. The Gaussian peak shape and good resolution typical of a GEM or p-type are maintained for the high count rates and peak separation needed for activation analysis. (author)

  1. Lowest-order corrections to the RPA polarizability and GW self-energy of a semiconducting wire

    NARCIS (Netherlands)

    Groot, de H.J.; Ummels, R.T.M.; Bobbert, P.A.; van Haeringen, W.

    1996-01-01

    We present the results of the addition of lowest-order vertex and self-consistency corrections to the RPA polarizability and the GW self-energy for a semiconducting wire. It is found that, when starting from a local density approximation zeroth-order Green function and systematically including these

  2. Vectorial mapping of noncollinear antiferromagnetic structure of semiconducting FeSe surface with spin-polarized scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, K. F.; Yang, Fang; Song, Y. R. [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Zhang, Xiaole [Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240 (China); The State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Chen, Xianfeng [The State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Liu, Canhua; Qian, Dong; Gao, C. L., E-mail: clgao@sjtu.edu.cn; Jia, Jin-Feng [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing (China); Luo, Weidong, E-mail: wdluo@sjtu.edu.cn [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing (China)

    2016-02-08

    Antiferromagnetic semiconductors gain increasing interest due to their possible application in spintronics. Using spin polarized scanning tunneling microscopy operating in a vector field, we mapped the noncollinear antiferromagnetic spin structure of a semiconducting hexagonal FeSe surface on the atomic scale. The surface possesses an in-plane compensated Néel structure which is further confirmed by first-principles calculations.

  3. Thin-film transistors with a channel composed of semiconducting metal oxide nanoparticles deposited from the gas phase

    International Nuclear Information System (INIS)

    Busch, C.; Schierning, G.; Theissmann, R.; Nedic, A.; Kruis, F. E.; Schmechel, R.

    2012-01-01

    The fabrication of semiconducting functional layers using low-temperature processes is of high interest for flexible printable electronics applications. Here, the one-step deposition of semiconducting nanoparticles from the gas phase for an active layer within a thin-film transistor is described. Layers of semiconducting nanoparticles with a particle size between 10 and 25 nm were prepared by the use of a simple aerosol deposition system, excluding potentially unwanted technological procedures like substrate heating or the use of solvents. The nanoparticles were deposited directly onto standard thin-film transistor test devices, using thermally grown silicon oxide as gate dielectric. Proof-of-principle experiments were done deploying two different wide-band gap semiconducting oxides, tin oxide, SnO x , and indium oxide, In 2 O 3 . The tin oxide spots prepared from the gas phase were too conducting to be used as channel material in thin-film transistors, most probably due to a high concentration of oxygen defects. Using indium oxide nanoparticles, thin-film transistor devices with significant field effect were obtained. Even though the electron mobility of the investigated devices was only in the range of 10 −6 cm 2V−1s−1 , the operability of this method for the fabrication of transistors was demonstrated. With respect to the possibilities to control the particle size and layer morphology in situ during deposition, improvements are expected.

  4. Vectorial mapping of noncollinear antiferromagnetic structure of semiconducting FeSe surface with spin-polarized scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Zhang, K. F.; Yang, Fang; Song, Y. R.; Zhang, Xiaole; Chen, Xianfeng; Liu, Canhua; Qian, Dong; Gao, C. L.; Jia, Jin-Feng; Luo, Weidong

    2016-01-01

    Antiferromagnetic semiconductors gain increasing interest due to their possible application in spintronics. Using spin polarized scanning tunneling microscopy operating in a vector field, we mapped the noncollinear antiferromagnetic spin structure of a semiconducting hexagonal FeSe surface on the atomic scale. The surface possesses an in-plane compensated Néel structure which is further confirmed by first-principles calculations

  5. Hole traps associated with high-concentration residual carriers in p-type GaAsN grown by chemical beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Elleuch, Omar, E-mail: mr.omar.elleuch@gmail.com; Wang, Li; Lee, Kan-Hua; Demizu, Koshiro; Ikeda, Kazuma; Kojima, Nobuaki; Ohshita, Yoshio; Yamaguchi, Masafumi [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya 468-8511 (Japan)

    2015-01-28

    The hole traps associated with high background doping in p-type GaAsN grown by chemical beam epitaxy are studied based on the changes of carrier concentration, junction capacitance, and hole traps properties due to the annealing. The carrier concentration was increased dramatically with annealing time, based on capacitance–voltage (C–V) measurement. In addition, the temperature dependence of the junction capacitance (C–T) was increased rapidly two times. Such behavior is explained by the thermal ionization of two acceptor states. These acceptors are the main cause of high background doping in the film, since the estimated carrier concentration from C–T results explains the measured carrier concentration at room temperature using C–V method. The acceptor states became shallower after annealing, and hence their structures are thermally unstable. Deep level transient spectroscopy (DLTS) showed that the HC2 hole trap was composed of two signals, labeled HC21 and HC22. These defects correspond to the acceptor levels, as their energy levels obtained from DLTS are similar to those deduced from C–T. The capture cross sections of HC21 and HC22 are larger than those of single acceptors. In addition, their energy levels and capture cross sections change in the same way due to the annealing. This tendency suggests that HC21 and HC22 signals originate from the same defect which acts as a double acceptor.

  6. Electrical and structural properties of surfaces and interfaces in Ti/Al/Ni Ohmic contacts to p-type implanted 4H-SiC

    Science.gov (United States)

    Vivona, M.; Greco, G.; Bongiorno, C.; Lo Nigro, R.; Scalese, S.; Roccaforte, F.

    2017-10-01

    In this work, the electrical and structural properties of Ti/Al/Ni Ohmic contacts to p-type implanted silicon carbide (4H-SiC) were studied employing different techniques. With increasing the annealing temperature, an improvement of the electrical properties of the contacts is highlighted, until an Ohmic behavior is obtained at 950 °C, with a specific contact resistance ρc = 2.3 × 10-4 Ω cm2. A considerable intermixing of the metal layers occurred upon annealing, as a consequence of the formation of different phases, both in the uppermost part of the stack (mainly Al3Ni2) and at the interface with SiC, where the formation of preferentially aligned TiC is observed. The formation of an Ohmic contact was associated with the occurrence of the reaction and the disorder at the interface, where the current transport is dominated by the thermionic field emission mechanism with a barrier height of 0.56 eV.

  7. Effect of Rapid Thermal Processing on Light-Induced Degradation of Carrier Lifetime in Czochralski p-Type Silicon Bare Wafers

    Science.gov (United States)

    Kouhlane, Y.; Bouhafs, D.; Khelifati, N.; Belhousse, S.; Menari, H.; Guenda, A.; Khelfane, A.

    2016-11-01

    The electrical properties of Czochralski silicon (Cz-Si) p-type boron-doped bare wafers have been investigated after rapid thermal processing (RTP) with different peak temperatures. Treated wafers were exposed to light for various illumination times, and the effective carrier lifetime ( τ eff) measured using the quasi-steady-state photoconductance (QSSPC) technique. τ eff values dropped after prolonged illumination exposure due to light-induced degradation (LID) related to electrical activation of boron-oxygen (BO) complexes, except in the sample treated with peak temperature of 785°C, for which the τ eff degradation was less pronounced. Also, a reduction was observed when using the 830°C peak temperature, an effect that was enhanced by alteration of the wafer morphology (roughness). Furthermore, the electrical resistivity presented good stability under light exposure as a function of temperature compared with reference wafers. Additionally, the optical absorption edge shifted to higher wavelength, leading to increased free-carrier absorption by treated wafers. Moreover, a theoretical model is used to understand the lifetime degradation and regeneration behavior as a function of illumination time. We conclude that RTP plays an important role in carrier lifetime regeneration for Cz-Si wafers via modification of optoelectronic and structural properties. The balance between an optimized RTP cycle and the rest of the solar cell elaboration process can overcome the negative effect of LID and contribute to achievement of higher solar cell efficiency and module performance.

  8. Hole traps associated with high-concentration residual carriers in p-type GaAsN grown by chemical beam epitaxy

    International Nuclear Information System (INIS)

    Elleuch, Omar; Wang, Li; Lee, Kan-Hua; Demizu, Koshiro; Ikeda, Kazuma; Kojima, Nobuaki; Ohshita, Yoshio; Yamaguchi, Masafumi

    2015-01-01

    The hole traps associated with high background doping in p-type GaAsN grown by chemical beam epitaxy are studied based on the changes of carrier concentration, junction capacitance, and hole traps properties due to the annealing. The carrier concentration was increased dramatically with annealing time, based on capacitance–voltage (C–V) measurement. In addition, the temperature dependence of the junction capacitance (C–T) was increased rapidly two times. Such behavior is explained by the thermal ionization of two acceptor states. These acceptors are the main cause of high background doping in the film, since the estimated carrier concentration from C–T results explains the measured carrier concentration at room temperature using C–V method. The acceptor states became shallower after annealing, and hence their structures are thermally unstable. Deep level transient spectroscopy (DLTS) showed that the HC2 hole trap was composed of two signals, labeled HC21 and HC22. These defects correspond to the acceptor levels, as their energy levels obtained from DLTS are similar to those deduced from C–T. The capture cross sections of HC21 and HC22 are larger than those of single acceptors. In addition, their energy levels and capture cross sections change in the same way due to the annealing. This tendency suggests that HC21 and HC22 signals originate from the same defect which acts as a double acceptor

  9. Transparent conductive p-type lithium-doped nickel oxide thin films deposited by pulsed plasma deposition

    Science.gov (United States)

    Huang, Yanwei; Zhang, Qun; Xi, Junhua; Ji, Zhenguo

    2012-07-01

    Transparent p-type Li0.25Ni0.75O conductive thin films were prepared on conventional glass substrates by pulsed plasma deposition. The effects of substrate temperature and oxygen pressure on structural, electrical and optical properties of the films were investigated. The electrical resistivity decreases initially and increases subsequently as the substrate temperature increases. As the oxygen pressure increases, the electrical resistivity decreases monotonically. The possible physical mechanism was discussed. And a hetero p-n junction of p-Li0.25Ni0.75O/n-SnO2:W was fabricated by depositing n-SnO2:W on top of the p-Li0.25Ni0.75O, which exhibits typical rectifying current-voltage characteristics.

  10. Transparent conductive p-type lithium-doped nickel oxide thin films deposited by pulsed plasma deposition

    International Nuclear Information System (INIS)

    Huang Yanwei; Zhang Qun; Xi Junhua; Ji Zhenguo

    2012-01-01

    Transparent p-type Li 0.25 Ni 0.75 O conductive thin films were prepared on conventional glass substrates by pulsed plasma deposition. The effects of substrate temperature and oxygen pressure on structural, electrical and optical properties of the films were investigated. The electrical resistivity decreases initially and increases subsequently as the substrate temperature increases. As the oxygen pressure increases, the electrical resistivity decreases monotonically. The possible physical mechanism was discussed. And a hetero p-n junction of p-Li 0.25 Ni 0.75 O/n-SnO 2 :W was fabricated by depositing n-SnO 2 :W on top of the p-Li 0.25 Ni 0.75 O, which exhibits typical rectifying current-voltage characteristics.

  11. Identifying individual n- and p-type ZnO nanowires by the output voltage sign of piezoelectric nanogenerator

    KAUST Repository

    Lin, S S

    2009-08-18

    Based on a comparative study between the piezoelectric outputs of n-type nanowires (NWs) and n-core/p-shell NWs along with the previous study (Lu et al 2009 Nano. Lett. 9 1223), we demonstrate a one-step technique for identifying the conductivity type of individual ZnO nanowires (NWs) based on the output of a piezoelectric nanogenerator without destroying the sample. A negative piezoelectric output voltage indicates an NW is n-type and it appears after the tip scans across the center of the NW, while a positive output voltage reveals p-type conductivity and it appears before the tip scans across the central line of the NW. This atomic force microscopy based technique is reliable for statistically mapping the majority carrier type in ZnO NWs arrays. The technique may also be applied to other wurtzite semiconductors, such as GaN, CdS and ZnS. © 2009 IOP Publishing Ltd.

  12. Expression of a prokaryotic P-type ATPase in E. coli Plasma Membranes and Purification by Ni2+-affinity chromatography

    Directory of Open Access Journals (Sweden)

    Geisler Markus

    1998-01-01

    Full Text Available In order to characterize the P-type ATPase from Synechocystis 6803 [Geisler (1993 et al. J. Mol. Biol. 234, 1284] and to facilitate its purification, we expressed an N-terminal 6xHis-tagged version of the ATPase in an ATPase deficient E. coli strain. The expressed ATPase was immunodetected as a dominant band of about 97 kDa localized to the E. coli plasma membranes representing about 20-25% of the membrane protein. The purification of the Synecho-cystis 6xHis-ATPase by single-step Ni-affinity chromatography under native and denaturating conditions is described. ATPase activity and the formation of phosphointermediates verify the full function of the enzyme: the ATPase is inhibited by vanadate (IC50= 119 &mgr;M and the formation of phosphorylated enzyme intermediates shown by acidic PAGE depends on calcium, indicating that the Synechocystis P-ATPase functions as a calcium pump.

  13. Low p-type contact resistance by field-emission tunneling in highly Mg-doped GaN

    Science.gov (United States)

    Okumura, Hironori; Martin, Denis; Grandjean, Nicolas

    2016-12-01

    Mg-doped GaN with a net acceptor concentration (NA-ND) in the high 1019 cm-3 range was grown using ammonia molecular-beam epitaxy. Electrical properties of NiO contact on this heavily doped p-type GaN were investigated. A potential-barrier height of 0.24 eV was extracted from the relationship between NA-ND and the specific contact resistivity (ρc). We found that there is an optimum NA-ND value of 5 × 1019 cm-3 for which ρc is as low as 2 × 10-5 Ω cm2. This low ρc is ascribed to hole tunneling through the potential barrier at the NiO/p+-GaN interface, which is well accounted for by the field-emission model.

  14. Control of N/N2 species ratio in NO plasma for p-type doping of ZnO

    International Nuclear Information System (INIS)

    Chen Xingyou; Zhang Zhenzhong; Jiang Mingming; Wang Shuangpeng; Li Binghui; Shan Chongxin; Liu Lei; Zhao Dongxu; Shen Dezhen; Yao Bin

    2011-01-01

    Nitrogen-doped ZnO thin films were grown on c-plane sapphire (Al 2 O 3 ) substrates via plasma-assisted molecular beam epitaxy using plasma activated nitric oxide (NO) as the oxygen source and dopant. X-ray diffraction measurements indicate that a small NO flux benefits the crystal quality of the thin films. Hall effect measurements indicate that the electron density of the ZnO films decreases gradually with decreasing NO flux, and the conduction reverses to p-type at a certain flux. Optical emission spectra indicate that the N atom content in the NO plasma increases with decreasing NO flux, and the origin of this is discussed. X-ray photoelectron spectroscopy measurements demonstrate that the number of N atom occupied O sites in the ZnO lattice increases correspondingly.

  15. p-type ZnO films with solid-source phosphorus doping by molecular-beam epitaxy

    International Nuclear Information System (INIS)

    Xiu, F.X.; Yang, Z.; Mandalapu, L.J.; Liu, J.L.; Beyermann, W. P.

    2006-01-01

    Phosphorus-doped p-type ZnO films were grown on r-plane sapphire substrates using molecular-beam epitaxy with a solid-source GaP effusion cell. X-ray diffraction spectra and reflection high-energy electron diffraction patterns indicate that high-quality single crystalline (1120) ZnO films were obtained. Hall and resistivity measurements show that the phosphorus-doped ZnO films have high hole concentrations and low resistivities at room temperature. Photoluminescence (PL) measurements at 8 K reveal a dominant acceptor-bound exciton emission with an energy of 3.317 eV. The acceptor energy level of the phosphorus dopant is estimated to be 0.18 eV above the valence band from PL spectra, which is also consistent with the temperature dependence of PL measurements

  16. Large-Scale Surfactant-Free Synthesis of p-Type SnTe Nanoparticles for Thermoelectric Applications

    Directory of Open Access Journals (Sweden)

    Guang Han

    2017-02-01

    Full Text Available A facile one-pot aqueous solution method has been developed for the fast and straightforward synthesis of SnTe nanoparticles in more than ten gram quantities per batch. The synthesis involves boiling an alkaline Na2SnO2 solution and a NaHTe solution for short time scales, in which the NaOH concentration and reaction duration play vital roles in controlling the phase purity and particle size, respectively. Spark plasma sintering of the SnTe nanoparticles produces nanostructured compacts that have a comparable thermoelectric performance to bulk counterparts synthesised by more time- and energy-intensive methods. This approach, combining an energy-efficient, surfactant-free solution synthesis with spark plasma sintering, provides a simple, rapid, and inexpensive route to p-type SnTe nanostructured materials.

  17. Formation of Ga2O3 by the oxidation of p-type GaN thin films

    Energy Technology Data Exchange (ETDEWEB)

    Pinnisch, Melanie; Reppin, Daniel; Stehr, Jan; Laufer, Andreas; Hofmann, Detlev M.; Meyer, Bruno K. [1. Physikalisches Institut, Justus-Liebig-University, Giessen (Germany)

    2010-07-01

    Both GaN and Ga{sub 2}O{sub 3} are wide band gap semiconductors with energies of 3.45 eV and 4.9 eV, respectively. While GaN can be achieved p- or n-type conducting by doping, Ga{sub 2}O{sub 3} is n-type or high resistive dependent on the presence of oxygen vacancies. We studied the conversion of p-type Mg doped GaN thin films to Ga{sub 2}O{sub 3} by thermal treatments in the temperature range from 600 C to 1200 C and in different atmospheres. Changes of the film properties were studied by means of X-ray diffraction, photo-electron spectroscopy and atomic force microscopy. Optical and magnetic resonance methods were used to investigate the evolution of the dopands and defects.

  18. The Influence Of Dead Layer Effect On The Characteristics Of The High Purity Germanium P-Type Detector

    International Nuclear Information System (INIS)

    Ngo Quang Huy

    2011-01-01

    The present work aims at reviewing the studies of the influence of dead layer effect on the characteristics of a high purity germanium (HPGe) p-type detector, obtained by the author and his colleagues in the recent years. The object for study was the HPGe GC1518 detector-based gamma spectrometer of the Center for Nuclear Techniques, Ho Chi Minh City. The studying problems were: The modeling of an HPGe detector-based gamma spectrometer with using the MCNP code; the method of determining the thickness of dead layer by experimental measurements of gamma spectra and the calculations using MCNP code; the influence of material parameters and dead layer on detector efficiency; the increase of dead layer thickness over the operating time of the GC1518 detector; the influence of dead layer thickness increase on the decrease of detector efficiency; the dead layer effect for the gamma spectra measured in the GC1518 detector. (author)

  19. Electronic structure of p type Delta doped systems; Estructura electronica de sistemas dopadas con Delta de tipo p

    Energy Technology Data Exchange (ETDEWEB)

    Gaggero S, L.M.; Perez A, R. [Departamento de Fisica de los Materiales, Universidad Nacional de Educacion a Distancia, Senda del Rey s/n, 28040 Madrid (Spain)

    1998-12-31

    We summarize of the results obtained for the electronic structure of quantum wells that consist in an atomic layer doped with impurities of p type. The calculations are made within the frame worth of the wrapper function approach to independent bands and with potentials of Hartree. We study the cases reported experimentally (Be in GaAs and B in Si). We present the levels of energy, the wave functions and the rate of the electronic population between the different subbands, as well as the dependence of these magnitudes with the density of impurities in the layer. The participation of the bans of heavy holes is analysed, light and split-off band in the total electronic population. The effect of the temperature is discussed and we give a possible qualitative explanation of the experimental optical properties. (Author)

  20. High temperature thermoelectric properties of p-type skutterudites BaxYbyCo4-zFezSb12

    KAUST Repository

    Dong, Y.

    2012-01-01

    Several polycrystalline p-type skutterudites with compositions Ba xYb yCo 4-zFe zSb 12, with varying filler concentrations x and y, and z = 1 to 2, were synthesized by reacting the constituents and subsequent solid state annealing, followed by densification by hot-pressing. Their thermoelectric properties were evaluated from 300 to 820 K. The Yb filling fraction increased with Fe content while the amount of Fe substitution had little influence on the Ba filling fraction. High purity specimens were obtained when the Fe content was low. Bipolar conduction contributed to the thermal conductivity at elevated temperatures. A maximum ZT value of 0.7 was obtained at 750 K for the specimen with the highest Fe content and filling fraction. The potential for thermoelectric applications is also discussed. © 2012 American Institute of Physics.

  1. P-type doping of semipolar GaN(11 anti 22) by plasma-assisted molecular-beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Das, A.; Lahourcade, L. [Equipe Mixte CEA-CNRS, Nanophysique et Semiconducteurs, CEA-Grenoble, INAC/SP2M, Grenoble (France); Pernot, J. [Institut Neel, CNRS et Universite Joseph Fourier, Grenoble (France); Valdueza-Felip, S. [Equipe Mixte CEA-CNRS, Nanophysique et Semiconducteurs, CEA-Grenoble, INAC/SP2M, Grenoble (France); Dept. Electronica, Escuela Politecnica, Universidad de Alcala, Alcala de Henares, Madrid (Spain); Ruterana, P. [CIMAP, UMR6252, CNRS-ENSICAEN-CEA-UCBN, Caen (France); Laufer, A.; Eickhoff, M. [I. Physikalisches Institut, Justus-Liebig-Universitaet Giessen (Germany); Monroy, E.

    2010-07-15

    We report the effect of Mg doping on the growth kinetics of semipolar GaN(11-22) synthesized by plasma-assisted molecular-beam epitaxy. Mg tends to segregate on the surface, inhibiting the formation of the self-regulated Ga film which is used as a surfactant for the growth of undoped and Si-doped GaN(11-22). As a result, the growth widow is reduced for Mg doped layers, and we observe a certain deterioration of the surface morphology. In spite of this difficulties, homogenous Mg incorporation is achieved and layers display p -type conductivity for Mg atomic concentration higher than 7 x 10{sup 18} cm{sup -3}. Microscopy studies show no evidence of the pyramidal defects or polarity inversion domains found in Mg-doped GaN(0001). (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Semiconducting properties of oxide and passive films formed on AISI 304 stainless steel and Alloy 600

    Directory of Open Access Journals (Sweden)

    Ferreira M. G. S.

    2002-01-01

    Full Text Available The semiconducting properties of passive films formed on AISI 304 stainless steel and Alloy 600 in borate buffer solution were studied by capacitance (Mott-Schottky approach and photocurrent measurements. Oxide films formed on 304 stainless steel in air at 350 ºC have also been studied. The results obtained show that, in all cases the electronic structure of the films is comparable to that of a p-n heterojunction in which the space charges developed at the metal-film and film-electrolyte interfaces have also to be considered. This is in accordance with analytical results showing that the oxide films are in all cases composed of an inner region rich in chromium oxide and an outer region rich in iron oxide.

  3. High-performance radio frequency transistors based on diameter-separated semiconducting carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Yu; Che, Yuchi; Zhou, Chongwu, E-mail: chongwuz@usc.edu [Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089 (United States); Seo, Jung-Woo T.; Hersam, Mark C. [Department of Materials Science and Engineering and Department of Chemistry, Northwestern University, Evanston, Illinois 60208 (United States); Gui, Hui [Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089 (United States)

    2016-06-06

    In this paper, we report the high-performance radio-frequency transistors based on the single-walled semiconducting carbon nanotubes with a refined average diameter of ∼1.6 nm. These diameter-separated carbon nanotube transistors show excellent transconductance of 55 μS/μm and desirable drain current saturation with an output resistance of ∼100 KΩ μm. An exceptional radio-frequency performance is also achieved with current gain and power gain cut-off frequencies of 23 GHz and 20 GHz (extrinsic) and 65 GHz and 35 GHz (intrinsic), respectively. These radio-frequency metrics are among the highest reported for the carbon nanotube thin-film transistors. This study provides demonstration of radio frequency transistors based on carbon nanotubes with tailored diameter distributions, which will guide the future application of carbon nanotubes in radio-frequency electronics.

  4. Domain wall conductivity in semiconducting hexagonal ferroelectric TbMnO3 thin films

    International Nuclear Information System (INIS)

    Kim, D J; Gruverman, A; Connell, J G; Seo, S S A

    2016-01-01

    Although enhanced conductivity of ferroelectric domain boundaries has been found in BiFeO 3 and Pb(Zr,Ti)O 3 films as well as hexagonal rare-earth manganite single crystals, the mechanism of the domain wall conductivity is still under debate. Using conductive atomic force microscopy, we observe enhanced conductance at the electrically-neutral domain walls in semiconducting hexagonal ferroelectric TbMnO 3 thin films where the structure and polarization direction are strongly constrained along the c-axis. This result indicates that domain wall conductivity in ferroelectric rare-earth manganites is not limited to charged domain walls. We show that the observed conductivity in the TbMnO 3 films is governed by a single conduction mechanism, namely, the back-to-back Schottky diodes tuned by the segregation of defects. (paper)

  5. Integration of Semiconducting Sulfides for Full-Spectrum Solar Energy Absorption and Efficient Charge Separation.

    Science.gov (United States)

    Zhuang, Tao-Tao; Liu, Yan; Li, Yi; Zhao, Yuan; Wu, Liang; Jiang, Jun; Yu, Shu-Hong

    2016-05-23

    The full harvest of solar energy by semiconductors requires a material that simultaneously absorbs across the whole solar spectrum and collects photogenerated electrons and holes separately. The stepwise integration of three semiconducting sulfides, namely ZnS, CdS, and Cu2-x S, into a single nanocrystal, led to a unique ternary multi-node sheath ZnS-CdS-Cu2-x S heteronanorod for full-spectrum solar energy absorption. Localized surface plasmon resonance (LSPR) in the nonstoichiometric copper sulfide nanostructures enables effective NIR absorption. More significantly, the construction of pn heterojunctions between Cu2-x S and CdS leads to staggered gaps, as confirmed by first-principles simulations. This band alignment causes effective electron-hole separation in the ternary system and hence enables efficient solar energy conversion. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Selective Growth of Metallic and Semiconducting Single Walled Carbon Nanotubes on Textured Silicon.

    Science.gov (United States)

    Jang, Mira; Lee, Jongtaek; Park, Teahee; Lee, Junyoung; Yang, Jonghee; Yi, Whikun

    2016-03-01

    We fabricated the etched Si substrate having the pyramidal pattern size from 0.5 to 4.2 μm by changing the texturing process parameters, i.e., KOH concentration, etching time, and temperature. Single walled carbon nanotubes (SWNTs) were then synthesized on the etched Si substrates with different pyramidal pattern by chemical vapor deposition. We investigated the optical and electronic properties of SWNT film grown on the etched Si substrates of different morphology by using scanning electron microscopy, Raman spectroscopy and conducting probe atomic force microscopy. We confirmed that the morphology of substrate strongly affected the selective growth of the SWNT film. Semiconducting SWNTs were formed on larger pyramidal sized Si wafer with higher ratio compared with SWNTs on smaller pyramidal sized Si.

  7. Excitons in semiconducting quantum filaments of CdS and CdSe with dielectric barriers

    CERN Document Server

    Dneprovskij, V S; Shalygina, O A; Lyaskovskij, V L; Mulyarov, E A; Gavrilov, S A; Masumoto, I

    2002-01-01

    The peculiarities of the luminescence spectra obtained by different polarization and intensity of the pumping excitation and luminescence kinetics of the CdS and CdSe nanocrystals are explained by the exciton transitions in the semiconducting quantum threads with dielectric barriers. The exciton transition energies correspond to the calculated ones with an account of both their dimensional quantization and the effect of the excitons dielectric intensification. It is shown that the excitons transition energies do not change by the change in the quantum threads diameter within the wide range, while the increase in the one-dimensional forbidden zone width of quantum thread by the decrease in its diameter is compensated through the decrease in the excitons binding energy

  8. Dithiopheneindenofluorene (TIF) Semiconducting Polymers with Very High Mobility in Field-Effect Transistors

    KAUST Repository

    Chen, Hu

    2017-07-19

    The charge-carrier mobility of organic semiconducting polymers is known to be enhanced when the energetic disorder of the polymer is minimized. Fused, planar aromatic ring structures contribute to reducing the polymer conformational disorder, as demonstrated by polymers containing the indacenodithiophene (IDT) repeat unit, which have both a low Urbach energy and a high mobility in thin-film-transistor (TFT) devices. Expanding on this design motif, copolymers containing the dithiopheneindenofluorene repeat unit are synthesized, which extends the fused aromatic structure with two additional phenyl rings, further rigidifying the polymer backbone. A range of copolymers are prepared and their electrical properties and thin-film morphology evaluated, with the co-benzothiadiazole polymer having a twofold increase in hole mobility when compared to the IDT analog, reaching values of almost 3 cm2 V−1 s−1 in bottom-gate top-contact organic field-effect transistors.

  9. La 1-x Ca x MnO 3 semiconducting nanostructures: morphology and thermoelectric properties.

    Science.gov (United States)

    Culebras, Mario; Torán, Raquel; Gómez, Clara M; Cantarero, Andrés

    2014-01-01

    Semiconducting metallic oxides, especially perosvkite materials, are great candidates for thermoelectric applications due to several advantages over traditionally metallic alloys such as low production costs and high chemical stability at high temperatures. Nanostructuration can be the key to develop highly efficient thermoelectric materials. In this work, La 1-x Ca x MnO 3 perosvkite nanostructures with Ca as a dopant have been synthesized by the hydrothermal method to be used in thermoelectric applications at room temperature. Several heat treatments have been made in all samples, leading to a change in their morphology and thermoelectric properties. The best thermoelectric efficiency has been obtained for a Ca content of x=0.5. The electrical conductivity and Seebeck coefficient are strongly related to the calcium content.

  10. Creation of paired electron states in the gap of semiconducting carbon nanotubes by correlated hydrogen adsorption

    International Nuclear Information System (INIS)

    Buchs, Gilles; Krasheninnikov, Arkady V; Ruffieux, Pascal; Groening, Pierangelo; Foster, Adam S; Nieminen, Risto M; Groening, Oliver

    2007-01-01

    The specific, local modification of the electronic structure of carbon nanomaterials is as important for novel electronic device fabrication as the doping in the case of silicon-based electronics. Here, we report low temperature scanning tunneling microscopy and spectroscopy study of semiconducting carbon nanotubes subjected to hydrogen-plasma treatment. We show that plasma treatment mostly results in the creation of paired electronic states in the nanotube band gap. Combined with extensive first-principle simulations, our results provide direct evidence that these states originate from correlated chemisorption of hydrogen adatoms on the tube surface. The energy splitting of the paired states is governed by the adatom-adatom interaction, so that controlled hydrogenation can be used for engineering the local electronic structure of nanotubes and other sp 2 -bonded nanocarbon systems

  11. Semiconducting polymer dot as a highly effective contrast agent for photoacoustic imaging

    Science.gov (United States)

    Yuan, Zhen; Zhang, Jian

    2018-02-01

    In this study, we developed a novel PIID-DTBT based semiconducting polymer dots (Pdots) that have broad and strong optical absorption in the visible-light region (500 nm - 700 nm). Gold nanoparticles (GNPs) and gold nanorods (GNRs) that have been verified as an excellent photoacoustic contrast agent were compared with Pdots based on photoacoustic imaging method. Both ex vivo and in vivo experiment demonstrated Pdots have a better photoacoustic conversion efficiency at 532 nm than GNPs and similar photoacoustic performance with GNRs at 700 nm at the same mass concentration. Our work demonstrates the great potential of Pdots as a highly effective contrast agent for precise localization of lesions relative to the blood vessels based on photoacoustic tomography imaging.

  12. Semiconducting properties of oxide films formed onto an Nb electrode in NaOH solutions

    Directory of Open Access Journals (Sweden)

    VLADIMIR D. JOVIC

    2008-03-01

    Full Text Available In this paper, the results of the potentiostatic formation of homogeneous and heterogeneous, nano-crystalline passive films of Nb2O5 onto an Nb electrode in NaOH solutions of different concentrations at potentials lower than 3.0 V vs. SCE are presented. The semiconducting properties of such films were investigated by EIS measurements. After fitting the EIS results by appropriate equivalent circuits, the space charge capacitance (Csc and space charge resistance (Rsc of these films were determined. The donor density (Nsc, flat band potential (Efb and thickness of the space charge layer (dsc for such oxide films were determined from the corresponding Mott–Schottky (M–S plots. It is shown that all oxide films were n-type semiconductors in a certain potential range.

  13. Molecular Design of Semiconducting Polymers for High-Performance Organic Electrochemical Transistors

    KAUST Repository

    Nielsen, Christian B.

    2016-07-22

    The organic electrochemical transistor (OECT), capable of transducing small ionic fluxes into electronic signals in an aqueous envi-ronment, is an ideal device to utilize in bioelectronic applications. Currently, most OECTs are fabricated with commercially availa-ble conducting poly(3,4-ethylenedioxythiophene) (PEDOT)-based suspensions and are therefore operated in depletion mode. Here, we present a series of semiconducting polymers designed to elucidate important structure-property guidelines required for accumulation mode OECT operation. We discuss key aspects relating to OECT performance such as ion and hole transport, elec-trochromic properties, operational voltage and stability. The demonstration of our molecular design strategy is the fabrication of accumulation mode OECTs that clearly outperform state-of-the-art PEDOT based devices, and show stability under aqueous oper-ation without the need for formulation additives and cross-linkers.

  14. Photosensitive semiconducting polymer-incorporated nanofibers for promoting the regeneration of skin wound

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Guorui [Institute of Materials Research and Engineering, A*STAR, 2 Fusionopolis Way, Innovis, #08-03, 138634 (Singapore); The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Xi' an Jiaotong University, School of Life Science and Technology, Xi' an 710049 (China); Li, Jun [Institute of Materials Research and Engineering, A*STAR, 2 Fusionopolis Way, Innovis, #08-03, 138634 (Singapore); Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ (United Kingdom); Li, Kai, E-mail: kai_li_cn@hotmail.com [Institute of Materials Research and Engineering, A*STAR, 2 Fusionopolis Way, Innovis, #08-03, 138634 (Singapore); Department of Radiology and Molecular Imaging Program at Stanford (MIPS), Stanford School of Medicine, Stanford, 94305 (United States)

    2017-01-01

    Photosensitive semiconducting polymer (SP) combined with light stimulation has shown the capability in promoting the proliferation of human dermal fibroblasts (HDFs). However, the high cytotoxicity of the used SP hindered its further application in bioactive scaffolds. In this contribution, we designed and synthesized a SP, poly (N,N-bis(2-octyldodecyl)-3,6-di(thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c] pyrrole-1,4-dione-alt-thieno[3,2-b]thiophene) (PDBTT) with low cytotoxicity and strong absorbance in red and near-infrared region (600–1200 nm). The photosensitive SP was then applied in electrospun poly(ε-caprolactone) (PCL) nanofibrous scaffold and evaluated its proliferative effect on HDFs under the illumination from red light-emitting diode (LED) with high tissue penetration. After 9 days of continuous stimulation, the hybrid electrospun PCL/PDBTT nanofibers with low cytotoxicity showed excellent support for HDFs adhesion, proliferation and collagen secretion than neat PCL nanofibers and HDFs on the stimulated PCL/PDBTT nanofibers gained typical spindle morphology, indicating the well cell spreading on the stimulated PCL/PDBTT nanofibers. The incorporation of functional materials within synthetic biomaterials could be a novel way in improving the performance of engineered tissue constructs by providing multiple cues (e.g. electrical stimulation) to the attached cells. - Highlights: • A photosensitive semiconducting polymer (SP) was applied in electrospun nanofibrous scaffold. • The SP-incorporated scaffold could promote cell proliferation upon light stimulation. • The designed photosensitive SP could be applied as functional material with low cost and high durability in skin tissue engineering.

  15. Electronic structure and quantum transport properties of metallic and semiconducting nanowires

    Science.gov (United States)

    Simbeck, Adam J.

    The future of the semiconductor industry hinges upon new developments to combat the scaling issues that currently afflict two main chip components: transistors and interconnects. For transistors this means investigating suitable materials to replace silicon for both the insulating gate and the semiconducting channel in order to maintain device performance with decreasing size. For interconnects this equates to overcoming the challenges associated with copper when the wire dimensions approach the confinement limit, as well as continuing to develop low-k dielectric materials that can assure minimal cross-talk between lines. In addition, such challenges make it increasingly clear that device design must move from a top-down to a bottom-up approach in which the desired electronic characteristics are tailored from first-principles. It is with such fundamental hurdles in mind that ab initio calculations on the electronic and quantum transport properties of nanoscale metallic and semiconducting wires have been performed. More specifically, this study seeks to elaborate on the role played by confinement, contacts, dielectric environment, edge decoration, and defects in altering the electronic and transport characteristics of such systems. As experiments continue to achieve better control over the synthesis and design of nanowires, these results are expected to become increasingly more important for not only the interpretation of electronic and transport trends, but also in engineering the electronic structure of nanowires for the needs of the devices of the future. For the metallic atomic wires, the quantum transport properties are first investigated by considering finite, single-atom chains of aluminum, copper, gold, and silver sandwiched between gold contacts. Non-equilibrium Green's function based transport calculations reveal that even in the presence of the contact the conductivity of atomic-scale aluminum is greater than that of the other metals considered. This is

  16. “Pesting”-like oxidation phenomenon of p-type filled skutterudite Ce{sub 0.9}Fe{sub 3}CoSb{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Pengfei [State Key Laboratory of High Performance Ceramic and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 DingXi Road, Shanghai 200050 (China); Xia, Xugui; Huang, Xiangyang; Gu, Ming [CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 DingXi Road, Shanghai 200050 (China); Qiu, Yuting [State Key Laboratory of High Performance Ceramic and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 DingXi Road, Shanghai 200050 (China); Chen, Lidong, E-mail: chenlidong@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramic and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 DingXi Road, Shanghai 200050 (China)

    2014-11-05

    Highlights: • Ce{sub 0.9}Fe{sub 3}Co{sub 1}Sb{sub 12} exhibits “pesting”-like oxidation phenomenon at high temperature. • The highest oxidation rate of Ce{sub 0.9}Fe{sub 3}Co{sub 1}Sb{sub 12} appears around 800 K. • Severe periodically oxide layer peeling-off behavior is observed around 800 K. • The co-existence of Fe and Co is responsible for the poor oxidation resistance. - Abstract: Oxidation behavior of p-type filled skutterudite Ce{sub 0.9}Fe{sub 3}CoSb{sub 12} in air was investigated and the oxidation mechanism was discussed in this study. Ce{sub 0.9}Fe{sub 3}CoSb{sub 12} exhibits interesting “pesting”-like oxidation phenomenon around 800 K. The bulk sample completely disintegrates into a crowd of plate-like particles under this temperature range after only 24 h exposure in air. However, this abnormal oxidation phenomenon is not observed at temperature below 750 K or above 850 K. This result is consistent with the thermogravimetry and derivative thermogravimetry measurements which show that the oxidation rate for Ce{sub 0.9}Fe{sub 3}CoSb{sub 12} around 800 K is the highest among 650–900 K. Microstructure observations suggest that this “pesting”-like oxidation is related with the severe periodically oxide layer peeling-off behavior around 800 K, which makes the Ce{sub 0.9}Fe{sub 3}CoSb{sub 12} samples are easy to be oxidized because the fresh substrate surface is always exposed to high concentration oxygen atmosphere. X-ray diffraction and X-ray photoelectron spectroscopy measurements indicated that in the oxide scale the direct contact of Fe{sup 3+}-oxide and CoSb{sub 2}O{sub 4} which possess different formation/growth rate and volume expansion coefficient should be responsible for this peculiar oxide layer peeling-off behavior around 800 K. This work can serve as an important reference for the designation of M{sub y}Fe{sub 4−x}Co{sub x}Sb{sub 12}-based skutterudite thermoelectric device.

  17. Investigation of Landau level spin reversal in (110) oriented p-type GaAs quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Isik, Nebile

    2009-09-01

    In this thesis, the Landau level crossing or anticrossing of hole levels has been investigated in p-type GaAs 400 Aa wide quantum wells. In magneto-transport measurements, this is evidenced with the presence of an anomalous peak in the longitudinal resistance measurements at {nu}=1. In the transversal resistance measurements, no signature of this anomalous peak is observed. By increasing the hole density in the quantum well by applying a top gate voltage, the position of the anomalous peak shifts to higher magnetic fields. At very high densities, anomalous peak disappears. By applying a back gate voltage, the electric field in the quantum well is tuned. A consequence is that the geometry of the quantum well is tuned from square to triangular. The anomalous peak position is shown to depend also on the back gate voltage applied. Temperature dependence of the peak height is consistent with thermal activation energy gap ({delta}/2= 135 {mu}eV). The activation energy gap as a function of the magnetic field has a parabolic like dependence, with the minimum of 135 {mu}eV at 4 T. The peak magnitude is observed to decrease with increasing temperature. An additional peak is observed at {nu}=2 minimum. This additional peak at {nu}=2 might be due to the higher Landau level crossing. The p-type quantum wells have been investigated by photoluminescence spectroscopy, as a function of the magnetic field. The polarization of the emitted light has been analyzed in order to distinguish between the transitions related to spin of electron {+-} 1/2 and spin of hole -+ 3/2. The transition energies of the lowest electron Landau levels with spin {+-} 1/2 and hole Landau levels with spin -+ 3/2 versus magnetic field show crossing at 4 T. The heavy hole Landau levels with spins {+-} 3/2 are obtained by the substraction of transition energies from the sum of lowest electron Landau level energy and the energy gap of GaAs. The heavy hole Landau levels show a crossing at 4 T. However, due to the

  18. Complete p-type activation in vertical-gradient freeze GaAs co-implanted with gallium and carbon

    Science.gov (United States)

    Horng, S. T.; Goorsky, M. S.

    1996-03-01

    High-resolution triple-axis x-ray diffractometry and Hall-effect measurements were used to characterize damage evolution and electrical activation in gallium arsenide co-implanted with gallium and carbon ions. Complete p-type activation of GaAs co-implanted with 5×1014 Ga cm-2 and 5×1014 C cm-2 was achieved after rapid thermal annealing at 1100 °C for 10 s. X-ray diffuse scattering was found to increase after rapid thermal annealing at 600-900 °C due to the aggregation of implantation-induced point defects. In this annealing range, there was ˜10%-72% activation. After annealing at higher annealing temperatures, the diffuse scattered intensity decreased drastically; samples that had been annealed at 1000 °C (80% activated) and 1100 °C (˜100% activated) exhibited reciprocal space maps that were indicative of high crystallinity. The hole mobility was about 60 cm2/V s for all samples annealed at 800 °C and above, indicating that the crystal perfection influences dopant activation more strongly than it influences mobility. Since the high-temperature annealing simultaneously increases dopant activation and reduces x-ray diffuse scattering, we conclude that point defect complexes which form at lower annealing temperatures are responsible for both the diffuse scatter and the reduced activation.

  19. Investigation of p-type depletion doping for InGaN/GaN-based light-emitting diodes

    Science.gov (United States)

    Zhang, Yiping; Zhang, Zi-Hui; Tan, Swee Tiam; Hernandez-Martinez, Pedro Ludwig; Zhu, Binbin; Lu, Shunpeng; Kang, Xue Jun; Sun, Xiao Wei; Demir, Hilmi Volkan

    2017-01-01

    Due to the limitation of the hole injection, p-type doping is essential to improve the performance of InGaN/GaN multiple quantum well light-emitting diodes (LEDs). In this work, we propose and show a depletion-region Mg-doping method. Here we systematically analyze the effectiveness of different Mg-doping profiles ranging from the electron blocking layer to the active region. Numerical computations show that the Mg-doping decreases the valence band barrier for holes and thus enhances the hole transportation. The proposed depletion-region Mg-doping approach also increases the barrier height for electrons, which leads to a reduced electron overflow, while increasing the hole concentration in the p-GaN layer. Experimentally measured external quantum efficiency indicates that Mg-doping position is vitally important. The doping in or adjacent to the quantum well degrades the LED performance due to Mg diffusion, increasing the corresponding nonradiative recombination, which is well supported by the measured carrier lifetimes. The experimental results are well numerically reproduced by modifying the nonradiative recombination lifetimes, which further validate the effectiveness of our approach.

  20. High hole mobility p-type GaN with low residual hydrogen concentration prepared by pulsed sputtering

    Science.gov (United States)

    Arakawa, Yasuaki; Ueno, Kohei; Kobayashi, Atsushi; Ohta, Jitsuo; Fujioka, Hiroshi

    2016-08-01

    We have grown Mg-doped GaN films with low residual hydrogen concentration using a low-temperature pulsed sputtering deposition (PSD) process. The growth system is inherently hydrogen-free, allowing us to obtain high-purity Mg-doped GaN films with residual hydrogen concentrations below 5 × 1016 cm-3, which is the detection limit of secondary ion mass spectroscopy. In the Mg profile, no memory effect or serious dopant diffusion was detected. The as-deposited Mg-doped GaN films showed clear p-type conductivity at room temperature (RT) without thermal activation. The GaN film doped with a low concentration of Mg (7.9 × 1017 cm-3) deposited by PSD showed hole mobilities of 34 and 62 cm2 V-1 s-1 at RT and 175 K, respectively, which are as high as those of films grown by a state-of-the-art metal-organic chemical vapor deposition apparatus. These results indicate that PSD is a powerful tool for the fabrication of GaN-based vertical power devices.

  1. Oxygen partial pressure effects on the RF sputtered p-type NiO hydrogen gas sensors

    Science.gov (United States)

    Turgut, Erdal; Çoban, Ömer; Sarıtaş, Sevda; Tüzemen, Sebahattin; Yıldırım, Muhammet; Gür, Emre

    2018-03-01

    NiO thin films were grown by Radio Frequency (RF) Magnetron Sputtering method under different oxygen partial pressures, which are 0.6 mTorr, 1.3 mTorr and 2.0 mTorr. The effects of oxygen partial pressures on the thin films were analyzed through Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Hall measurements. The change in the surface morphology of the thin films has been observed with the SEM and AFM measurements. While nano-pyramids have been obtained on the thin film grown at the lowest oxygen partial pressure, the spherical granules lower than 60 nm in size has been observed for the samples grown at higher oxygen partial pressures. The shift in the dominant XRD peak is realized to the lower two theta angle with increasing the oxygen partial pressures. XPS measurements showed that the Ni2p peak involves satellite peaks and two oxidation states of Ni, Ni2+ and Ni3+, have been existed together with the corresponding splitting in O1s spectrum. P-type conductivity of the grown NiO thin films are confirmed by the Hall measurements with concentrations on the order of 1013 holes/cm-3. Gas sensor measurements revealed minimum of 10% response to the 10 ppm H2 level. Enhanced responsivity of the gas sensor devices of NiO thin films is shown as the oxygen partial pressure increases.

  2. LHCb-VELO module production with n-side read-out on n- and p-type silicon substrates

    International Nuclear Information System (INIS)

    Affolder, A.; Bowcock, T.J.V.; Carrol, J.L.; Casse, G.; Huse, T.; Patel, G.D.; Rinnert, K.; Smith, N.A.; Turner, P.R.

    2007-01-01

    The modules for the Vertex Locator detector of the LHCb experiment represent a technical challenge for their complexity. The design of the sensors uses a complex double metal routing of the connection to the read-out strips and a high density of metal lines has to be accommodated in the module. The detectors are n-side read-out to be able to survive the highest radiation damage of any micro-strip sensor used in LHC experiments. The present choice is n-strips on n-type substrates (n-in-n geometry). Double-sided lithography is required, which impact on the cost of the devices and on the module construction. Moreover, the compact size of the hybrid imposes sophisticated technical solutions for cooling the electronics and the detector. The module construction and the possible benefits offered by the choice of p-type substrate detectors compared to the present n-in-n devices are here discussed in details

  3. Cu gettering by phosphorus-doped emitters in p-type silicon: Effect on light-induced degradation

    Science.gov (United States)

    Inglese, Alessandro; Laine, Hannu S.; Vähänissi, Ville; Savin, Hele

    2018-01-01

    The presence of copper (Cu) contamination is known to cause relevant light-induced degradation (Cu-LID) effects in p-type silicon. Due to its high diffusivity, Cu is generally regarded as a relatively benign impurity, which can be readily relocated during device fabrication from the wafer bulk, i.e. the region affected by Cu-LID, to the surface phosphorus-doped emitter. This contribution examines in detail the impact of gettering by industrially relevant phosphorus layers on the strength of Cu-LID effects. We find that phosphorus gettering does not always prevent the occurrence of Cu-LID. Specifically, air-cooling after an isothermal anneal at 800°C results in only weak impurity segregation to the phosphorus-doped layer, which turns out to be insufficient for effectively mitigating Cu-LID effects. Furthermore, we show that the gettering efficiency can be enhanced through the addition of a slow cooling ramp (-4°C/min) between 800°C and 600°C, resulting in the nearly complete disappearance of Cu-LID effects.

  4. Deep levels in p-type InGaAsN lattice matched to GaAs

    International Nuclear Information System (INIS)

    Kwon, D.; Kaplar, R.J.; Ringel, S.A.; Allerman, A.A.; Kurtz, S.R.; Jones, E.D.

    1999-01-01

    Deep-level transient spectroscopy measurements were utilized to investigate deep-level defects in metal - organic chemical vapor deposition-grown, unintentionally doped p-type InGaAsN films lattice matched to GaAs. The as-grown material displayed a high concentration of deep levels distributed within the band gap, with a dominant hole trap at E v +0.10eV. Postgrowth annealing simplified the deep-level spectra, enabling the identification of three distinct hole traps at 0.10, 0.23, and 0.48 eV above the valence-band edge, with concentrations of 3.5x10 14 , 3.8x10 14 , and 8.2x10 14 cm -3 , respectively. A direct comparison between the as-grown and annealed spectra revealed the presence of an additional midgap hole trap, with a concentration of 4x10 14 cm -3 in the as-grown material. The concentration of this trap is sharply reduced by annealing, which correlates with improved material quality and minority-carrier properties after annealing. Of the four hole traps detected, only the 0.48 eV level is not influenced by annealing, suggesting this level may be important for processed InGaAsN devices in the future. copyright 1999 American Institute of Physics

  5. Characterization of anodic SiO2 films on P-type 4H-SiC

    International Nuclear Information System (INIS)

    Woon, W.S.; Hutagalung, S.D.; Cheong, K.Y.

    2009-01-01

    The physical and electronic properties of 100-120-nm thick anodic silicon dioxide film grown on p-type 4H-SiC wafer and annealed at different temperatures (500, 600, 700, and 800 deg. C ) have been investigated and reported. Chemical bonding of the films has been analyzed by Fourier transform infra red spectroscopy. Smooth and defect-free film surface has been revealed under field emission scanning electron microscope. Atomic force microscope has been used to study topography and surface roughness of the films. Electronic properties of the film have been investigated by high frequency capacitance-voltage and current-voltage measurements. As the annealing temperature increased, refractive index, dielectric constant, film density, SiC surface roughness, effective oxide charge, and leakage current density have been reduced until 700 deg. C . An increment of these parameters has been observed after this temperature. However, a reversed trend has been demonstrated in porosity of the film and barrier height between conduction band edge of SiO 2 and SiC

  6. Charge-Transfer-Induced p-Type Channel in MoS2 Flake Field Effect Transistors.

    Science.gov (United States)

    Min, Sung-Wook; Yoon, Minho; Yang, Sung Jin; Ko, Kyeong Rok; Im, Seongil

    2018-01-31

    The two-dimensional transition-metal dichalcogenide semiconductor MoS 2 has received extensive attention for decades because of its outstanding electrical and mechanical properties for next-generation devices. One weakness of MoS 2 , however, is that it shows only n-type conduction, revealing its limitations for homogeneous PN diodes and complementary inverters. Here, we introduce a charge-transfer method to modify the conduction property of MoS 2 from n- to p-type. We initially deposited an n-type InGaZnO (IGZO) film on top of the MoS 2 flake so that electron charges might be transferred from MoS 2 to IGZO during air ambient annealing. As a result, electron charges were depleted in MoS 2 . Such charge depletion lowered the MoS 2 Fermi level, which makes hole conduction favorable in MoS 2 when optimum source/drain electrodes with a high work function are selected. Our IGZO-supported MoS 2 flake field effect transistors (FETs) clearly display channel-type conversion from n- to p-channel in this way. Under short- and long-annealing conditions, n- and p-channel MoS 2 FETs are achieved, respectively, and a low-voltage complementary inverter is demonstrated using both channels in a single MoS 2 flake.

  7. Effects of the multi-step activation process on the carrier concentration of p-type GaN

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae-Kwan [Department of Materials Science and Metallurgical Engineering, Sunchon National University, Sunchon, Chonnam 540-742 (Korea, Republic of); Jeon, Seong-Ran [LED Research and Business Division, Korea Photonics Technology Institute, Gwanju 500-779 (Korea, Republic of); Lee, Ji-Myon, E-mail: jimlee@sunchon.ac.kr [Department of Printed Electronics Engineering, Sunchon National University, Sunchon, Chonnam 540-742 (Korea, Republic of)

    2014-06-25

    Highlights: • Hole concentration of p-GaN was enhanced by multi-step activation process. • The O{sub 2} plasma treatment is attributed to the enhanced hole concentration of p-GaN. • PL peak intensity was also enhanced by MS activation process. - Abstract: A multi-step activation method, which include an oxygen plasma treatment, chemical treatment, and post annealing in N{sub 2} was proposed to enhance the hole concentration of a p-type GaN epitaxial layer. This process was found to effectively activate p-GaN by increasing the hole concentration compared to that of the conventionally annealed sample. After the optimal oxygen plasma treatment (10 min at a source and table power of 500 W and 100 W, respectively), followed by a HCl and buffered oxide etchant treatment, and then by a post-RTA process in a N{sub 2} environment, the hole concentration was increased from 4.0 × 10{sup 17} to 2.0 × 10{sup 18} cm{sup −3}. The oxygen plasma was found to effectively remove the remaining H atoms and subsequent wet treatment can effectively remove the GaO{sub x} that had formed during O plasma treatment, resulting in the higher intensity of photoluminescence.

  8. Studies of defects in neutron-irradiated p-type silicon by admittance measurements of n+-p diodes

    International Nuclear Information System (INIS)

    Tokuda, Y.; Usami, A.

    1978-01-01

    Defects introduced in p-type silicon by neutron irradiation were studied by measuring the admittance of n + -p diodes. It was shown that the energy levels and capture cross sections estimated from the temperature dependence of the admittance had some uncertainty due to the temperature dependence of the concentration of free carriers in the bulk and the high-frequency-junction capacitance. So, we presented the method of determination of the energy levels, capture cross sections, and concentrations of defects from the frequency dependence of the admittance. This method consists of the measurements of G/ω and C as a function of frequency. From this method, assuming that capture cross sections are independent of temperature, the energy levels of E/sub v/+0.16 and E/sub v/+0.36 eV were obtained. For these defects, the calculated values of the hole capture cross section were 2.4 x 10 -14 and 3.7 x 10 -14 cm 2 , respectively. Comparing with other published data, the energy level of E/sub v/+0.36 eV was found to be correlated with the divacancy

  9. The Optimum Fabrication Condition of p-Type Antimony Tin Oxide Thin Films Prepared by DC Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    Huu Phuc Dang

    2016-01-01

    Full Text Available Transparent Sb-doped tin oxide (ATO thin films were fabricated on quartz glass substrates via a mixed (SnO2 + Sb2O3 ceramic target using direct current (DC magnetron sputtering in ambient Ar gas at a working pressure of 2 × 10−3 torr. X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, Hall-effect, and UV-vis spectra measurements were performed to characterize the deposited films. The substrate temperature of the films was investigated in two ways: (1 films were annealed in Ar ambient gas after being deposited at room temperature or (2 they were deposited directly at different temperatures. The first process for fabricating the ATO films was found to be easier than the second process. The deposited films showed p-type electrical properties, a polycrystalline tetragonal rutile structure, and their average transmittance was greater than 80% in the visible light range at the optimum annealing temperature of 500°C. The best electrical properties of the film were obtained on a 10 wt% Sb2O3-doped SnO2 target with a resistivity, hole concentration, and Hall mobility of 0.55 Ω·cm, 1.2 × 1019 cm−3, and 0.54 cm2V−1s−1, respectively.

  10. Thermal stability of Ni/Ti/Al ohmic contacts to p-type 4H-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hailong; Shen, Huajun, E-mail: shenhuajun@ime.ac.cn; Tang, Yidan; Bai, Yun; Liu, Xinyu [Microwave Device and IC Department, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029 (China); Zhang, Xufang [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Wu, Yudong; Liu, Kean [Zhuzhou CSR Times Electric Co., Ltd, ZhuZhou 412001 (China)

    2015-01-14

    Low resistivity Ni/Ti/Al ohmic contacts on p-type 4H-SiC epilayer were developed, and their thermal stabilities were also experimentally investigated through high temperature storage at 600 °C for 100 h. The contact resistance of the Al/Ti/Ni/SiC contacts degraded in different degrees, and the contact morphology deteriorated with the increases of the average surface roughness and interface voids. X-ray spectra showed that Ni{sub 2}Si and Ti{sub 3}SiC{sub 2}, which were formed during ohmic contact annealing and contributed to low contact resistivity, were stable under high temperature storage. The existence of the TiAl{sub 3} and NiAl{sub 3} intermetallic phases was helpful to prevent Al agglomeration on the interface and make the contacts thermally stable. Auger electron spectroscopy indicated that the incorporation of oxygen at the surface and interface led to the oxidation of Al or Ti resulting in increased contact resistance. Also, the formation of these oxides roughened the surface and interface. The temperature-dependence of the specific contact resistance indicated that a thermionic field emission mechanism dominates the current transport for contacts before and after the thermal treatment. It suggests that the Ni/Ti/Al composite ohmic contacts are promising for SiC devices to be used in high temperature applications.

  11. Effect of doping concentration on the conductivity and optical properties of p-type ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Pathak, Trilok Kumar [Semiconductor Research Lab, Department of Physics, Gurukula Kangri University, Haridwar (India); Kumar, Vinod, E-mail: vinod.phy@gmail.com [Department of Physics, University of the Free State, Bloemfontein (South Africa); Swart, H.C., E-mail: swarthc@ufs.ac.za [Department of Physics, University of the Free State, Bloemfontein (South Africa); Purohit, L.P., E-mail: proflppurohitphys@gmail.com [Semiconductor Research Lab, Department of Physics, Gurukula Kangri University, Haridwar (India)

    2016-01-01

    Nitrogen doped ZnO (NZO) thin films were synthesized on glass substrates by the sol–gel and spin coating method. Zinc acetate dihydrates and ammonium acetate were used as precursors for zinc and nitrogen, respectively. X-ray diffraction study showed that the thin films have a hexagonal wurtzite structure corresponding (002) peak for undoped and doped ZnO thin films. The transmittance of the films was above 80% and the band gap of the film varies from 3.21±0.03 eV for undoped and doped ZnO. The minimum resistivity of NZO thin films was obtained as 0.473 Ω cm for the 4 at% of nitrogen (N) doping with a mobility of 1.995 cm{sup 2}/V s. The NZO thin films showed p-type conductivity at 2 and 3 at% of N doping. The AC conductivity measurements that were carried out in the frequency range 10 kHz to 0.1 MHz showed localized conduction in the NZO thin films. These highly transparent ZnO films can be used as a possible window layer in solar cells.

  12. Dependencies of surface plasmon coupling effects on the p-GaN thickness of a thin-p-type light-emitting diode.

    Science.gov (United States)

    Su, Chia-Ying; Lin, Chun-Han; Yao, Yu-Feng; Liu, Wei-Heng; Su, Ming-Yen; Chiang, Hsin-Chun; Tsai, Meng-Che; Tu, Charng-Gan; Chen, Hao-Tsung; Kiang, Yean-Woei; Yang, C C

    2017-09-04

    The high performance of a light-emitting diode (LED) with the total p-type thickness as small as 38 nm is demonstrated. By increasing the Mg doping concentration in the p-AlGaN electron blocking layer through an Mg pre-flow process, the hole injection efficiency can be significantly enhanced. Based on this technique, the high LED performance can be maintained when the p-type layer thickness is significantly reduced. Then, the surface plasmon coupling effects, including the enhancement of internal quantum efficiency, increase in output intensity, reduction of efficiency droop, and increase of modulation bandwidth, among the thin p-type LED samples of different p-type thicknesses that are compared. These advantageous effects are stronger as the p-type layer becomes thinner. However, the dependencies of these effects on p-type layer thickness are different. With a circular mesa size of 10 μm in radius, through surface plasmon coupling, we achieve the record-high modulation bandwidth of 625.6 MHz among c-plane GaN-based LEDs.

  13. High-Purity Semiconducting Single-Walled Carbon Nanotubes: A Key Enabling Material in Emerging Electronics.

    Science.gov (United States)

    Lefebvre, Jacques; Ding, Jianfu; Li, Zhao; Finnie, Paul; Lopinski, Gregory; Malenfant, Patrick R L

    2017-10-17

    Semiconducting single-walled carbon nanotubes (sc-SWCNTs) are emerging as a promising material for high-performance, high-density devices as well as low-cost, large-area macroelectronics produced via additive manufacturing methods such as roll-to-roll printing. Proof-of-concept demonstrations have indicated the potential of sc-SWCNTs for digital electronics, radiofrequency circuits, radiation hard memory, improved sensors, and flexible, stretchable, conformable electronics. Advances toward commercial applications bring numerous opportunities in SWCNT materials development and characterization as well as fabrication processes and printing technologies. Commercialization in electronics will require large quantities of sc-SWCNTs, and the challenge for materials science is the development of scalable synthesis, purification, and enrichment methods. While a few synthesis routes have shown promising results in making near-monochiral SWCNTs, gram quantities are available only for small-diameter sc-SWCNTs, which underperform in transistors. Most synthesis routes yield mixtures of SWCNTs, typically 30% metallic and 70% semiconducting, necessitating the extraction of sc-SWCNTs from their metallic counterparts in high purity using scalable postsynthetic methods. Numerous routes to obtain high-purity sc-SWCNTs from raw soot have been developed, including density-gradient ultracentrifugation, chromatography, aqueous two-phase extraction, and selective DNA or polymer wrapping. By these methods (termed sorting or enrichment), >99% sc-SWCNT content can be achieved. Currently, all of these approaches have drawbacks and limitations with respect to electronics applications, such as excessive dilution, expensive consumables, and high ionic impurity content. Excess amount of dispersant is a common challenge that hinders direct inclusion of sc-SWCNTs into electronic devices. At present, conjugated polymer extraction may represent the most practical route to sc-SWCNTs. By the use of

  14. Hierarchical heterostructures of p-type bismuth oxychloride nanosheets on n-type zinc ferrite electrospun nanofibers with enhanced visible-light photocatalytic activities and magnetic separation properties.

    Science.gov (United States)

    Sun, Yucong; Shao, Changlu; Li, Xinghua; Guo, Xiaohui; Zhou, Xuejiao; Li, Xiaowei; Liu, Yichun

    2018-04-15

    P-type bismuth oxychloride (p-BiOCl) nanosheets were uniformly grown on n-type zinc ferrite (n-ZnFe 2 O 4 ) electrospun nanofibers via a solvothermal technique to form hierarchical heterostructures of p-BiOCl/n-ZnFe 2 O 4 (p-BiOCl/n-ZnFe 2 O 4 H-Hs). The density and loading amounts of the BiOCl nanosheets with exposed {0 0 1} facets were easily controlled by adjusting the reactant concentration in the solvothermal process. The p-BiOCl/n-ZnFe 2 O 4 H-Hs exhibited enhanced visible-light photocatalytic activities for the degradation of Rhodamine B (RhB). The apparent first-order rate of the p-BiOCl/n-ZnFe 2 O 4 H-Hs and its normalized constant were about 12.6- and 8-fold higher than pure ZnFe 2 O 4 nanofibers. This suggests that both the improved charge separation efficiency from the uniform p-n heterojunctions and the enlarged active surface sites from the hierarchical structures increase the photocatalytic performances. Furthermore, the p-BiOCl/n-ZnFe 2 O 4 H-Hs could be efficiently separated from the solution with an external magnetic field via the ferromagnetic behavior of ZnFe 2 O 4 nanofibers. The magnetic p-BiOCl/n-ZnFe 2 O 4 H-Hs with enhanced visible-light photocatalytic performances might have potential applications in water treatment. Copyright © 2018. Published by Elsevier Inc.

  15. Characterization of stain etched p-type silicon in aqueous HF solutions containing HNO{sub 3} or KMnO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Mogoda, A.S., E-mail: awad_mogoda@hotmail.com [Department of Chemistry, Faculty of Science, Cairo University, Giza (Egypt); Ahmad, Y.H.; Badawy, W.A. [Department of Chemistry, Faculty of Science, Cairo University, Giza (Egypt)

    2011-04-15

    Research highlights: {yields} Stain etching of p-Si in aqueous HF solutions containing HNO{sub 3} or KMnO{sub 4} was investigated. {yields} The electrical conductivity of the etched Si surfaces was measured using impedance technique. {yields} Scanning electron microscope and energy disperse X-ray were used to analyze the etched surfaces. {yields} Etching in aqueous HF solution containing HNO{sub 3} led to formation of a porous silicon layer. {yields} The formation of the porous silicon layer in HF/KMnO{sub 4} was accompanied by deposition of K{sub 2}SiF{sub 6} on the pores surfaces. - Abstract: Stain etching of p-type silicon in hydrofluoric acid solutions containing nitric acid or potassium permanganate as an oxidizing agent has been examined. The effects of etching time, oxidizing agent and HF concentrations on the electrochemical behavior of etched silicon surfaces have been investigated by electrochemical impedance spectroscopy (EIS). An electrical equivalent circuit was used for fitting the impedance data. The morphology and the chemical composition of the etched Si surface were studied using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques, respectively. A porous silicon layer was formed on Si etched in HF solutions containing HNO{sub 3}, while etching in HF solutions containing KMnO{sub 4} led to the formation of a porous layer and simultaneous deposition of K{sub 2}SiF{sub 6} inside the pores. The thickness of K{sub 2}SiF{sub 6} layer increases with increasing the KMnO{sub 4} concentration and decreases as the concentration of HF increases.

  16. Stable solar-driven oxidation of water by semiconducting photoanodes protected by transparent catalytic nickel oxide films.

    Science.gov (United States)

    Sun, Ke; Saadi, Fadl H; Lichterman, Michael F; Hale, William G; Wang, Hsin-Ping; Zhou, Xinghao; Plymale, Noah T; Omelchenko, Stefan T; He, Jr-Hau; Papadantonakis, Kimberly M; Brunschwig, Bruce S; Lewis, Nathan S

    2015-03-24

    Reactively sputtered nickel oxide (NiOx) films provide transparent, antireflective, electrically conductive, chemically stable coatings that also are highly active electrocatalysts for the oxidation of water to O2(g). These NiOx coatings provide protective layers on a variety of technologically important semiconducting photoanodes, including textured crystalline Si passivated by amorphous silicon, crystalline n-type cadmium telluride, and hydrogenated amorphous silicon. Under anodic operation in 1.0 M aqueous potassium hydroxide (pH 14) in the presence of simulated sunlight, the NiOx films stabilized all of these self-passivating, high-efficiency semiconducting photoelectrodes for >100 h of sustained, quantitative solar-driven oxidation of water to O2(g).

  17. Electrostatic potential in a bent piezoelectric nanowire with consideration of size-dependent piezoelectricity and semiconducting characterization.

    Science.gov (United States)

    Wang, Kaifa; Wang, Baolin

    2018-03-26

    Determining the electric potential in a bent piezoelectric nanowire (NW) is a fundamental issue of nanogenerators and nanopiezotronics. The combined influence of the flexoelectric effect, the semiconducting performance and the angle of atomic force microscope (AFM) tip has never been studied previously and will be investigated in this paper. The exact solution for the electric potential of a bent piezoelectric semiconductor NW is derived. The electric potential of the present model with consideration of flexoelectric effect varies along the length of the NW and is different from that of the classical piezoelectric model. Flexoelectric effect enhances but the semiconducting performance reduces the electric potential of the NW. In addition, it is found that if the angle of the AFM tip reaches 30 degrees, the error of the electric potential obtained from the model ignored the effect of the angle of the AFM tip is almost 16%, which is unacceptable. © 2018 IOP Publishing Ltd.

  18. Investigation of spin-gapless semiconductivity and half-metallicity in Ti2MnAl-based compounds

    International Nuclear Information System (INIS)

    Lukashev, P.; Staten, B.; Hurley, N.; Kharel, P.; Gilbert, S.; Fuglsby, R.; Huh, Y.; Valloppilly, S.; Zhang, W.; Skomski, R.; Sellmyer, D. J.; Yang, K.

    2016-01-01

    The increasing interest in spin-based electronics has led to a vigorous search for new materials that can provide a high degree of spin polarization in electron transport. An ideal candidate would act as an insulator for one spin channel and a conductor or semiconductor for the opposite spin channel, corresponding to the respective cases of half-metallicity and spin-gapless semiconductivity. Our first-principle electronic-structure calculations indicate that the metallic Heusler compound Ti 2 MnAl becomes half-metallic and spin-gapless semiconducting if half of the Al atoms are replaced by Sn and In, respectively. These electronic structures are associated with structural transitions from the regular cubic Heusler structure to the inverted cubic Heusler structure.

  19. Electrostatic potential in a bent piezoelectric nanowire with consideration of size-dependent piezoelectricity and semiconducting characterization

    Science.gov (United States)

    Wang, K. F.; Wang, B. L.

    2018-06-01

    Determining the electric potential in a bent piezoelectric nanowire (NW) is a fundamental issue of nanogenerators and nanopiezotronics. The combined influence of the flexoelectric effect, the semiconducting performance and the angle of atomic force microscope (AFM) tip has never been studied previously and will be investigated in this paper. The exact solution for the electric potential of a bent piezoelectric semiconductor NW is derived. The electric potential of the present model with consideration of flexoelectric effect varies along the length of the NW and is different from that of the classical piezoelectric model. Flexoelectric effect enhances but the semiconducting performance reduces the electric potential of the NW. In addition, it is found that if the angle of the AFM tip reaches 30°, the error of the electric potential obtained from the model ignored the effect of the angle of the AFM tip is almost 16%, which is unacceptable.

  20. First-principles study of direct and narrow band gap semiconducting β-CuGaO2

    International Nuclear Information System (INIS)

    Nguyen, Manh Cuong; Zhao, Xin; Wang, Cai-Zhuang; Ho, Kai-Ming

    2015-01-01

    Semiconducting oxides have attracted much attention due to their great stability in air or water and the abundance of oxygen. Recent success in synthesizing a metastable phase of CuGaO 2 with direct narrow band gap opens up new applications of semiconducting oxides as absorber layer for photovoltaics. Using first-principles density functional theory calculations, we investigate the thermodynamic and mechanical stabilities as well as the structural and electronic properties of the β-CuGaO 2 phase. Our calculations show that the β-CuGaO 2 structure is dynamically and mechanically stable. The energy band gap is confirmed to be direct at the Γ point of Brillouin zone. The optical absorption occurs right at the band gap edge and the density of states near the valance band maximum is large, inducing an intense absorption of light as observed in experiment. (paper)

  1. Stable solar-driven oxidation of water by semiconducting photoanodes protected by transparent catalytic nickel oxide films

    KAUST Repository

    Sun, Ke

    2015-03-11

    Reactively sputtered nickel oxide (NiOx) films provide transparent, antireflective, electrically conductive, chemically stable coatings that also are highly active electrocatalysts for the oxidation of water to O2(g). These NiOx coatings provide protective layers on a variety of technologically important semiconducting photoanodes, including textured crystalline Si passivated by amorphous silicon, crystalline n-type cadmium telluride, and hydrogenated amorphous silicon. Under anodic operation in 1.0 M aqueous potassium hydroxide (pH 14) in the presence of simulated sunlight, the NiOx films stabilized all of these self-passivating, high-efficiency semiconducting photoelectrodes for >100 h of sustained, quantitative solar-driven oxidation of water to O2(g). © 2015, National Academy of Sciences. All rights reserved.

  2. Discovering a Defect that Imposes a Limit to Mg Doping in p-Type GaN

    International Nuclear Information System (INIS)

    Liliental-Weber, Z.; Tomaszewicz, T.; Zakharov, D.; O'Keefe, M.A.

    2006-01-01

    Gallium nitride (GaN) is the III-V semiconductor used to produce blue light-emitting diodes (LEDs) and blue and ultraviolet solid-state lasers. To be useful in electronic devices, GaN must be doped with elements that function either as electron donors or as acceptors to turn it into either an n-type semiconductor or a p-type semiconductor. It has been found that GaN can easily be grown with n-conductivity, even up to large concentrations of donors--in the few 10 19 cm -3 range. However, p-doping, the doping of the structure with atoms that provide electron sinks or holes, is not well understood and remains extremely difficult. The only efficient p-type dopant is Mg, but it is found that the free hole concentration is limited to 2 x 10 18 cm -3 , even when Mg concentrations are pushed into the low 10 19 cm -3 range. This saturation effect could place a limit on further development of GaN based devices. Further increase of the Mg concentration, up to 1 x 10 20 cm -3 leads to a decrease of the free hole concentration and an increase in defects. While low- to medium-brightness GaN light-emitting diodes (LEDs) are remarkably tolerant of crystal defects, blue and UV GaN lasers are much less so. We used electron microscopy to investigate Mg doping in GaN. Our transmission electron microscopy (TEM) studies revealed the formation of different types of Mg-rich defects [1,2]. In particular, high-resolution TEM allowed us to characterize a completely new type of defect in Mg-rich GaN. We found that the type of defect depended strongly on crystal growth polarity. For crystals grown with N-polarity, planar defects are distributed at equal distances (20 unit cells of GaN); these defects can be described as inversion domains [1]. For growth with Ga-polarity, we found a different type of defect [2]. These defects turn out to be three-dimensional Mg-rich hexagonal pyramids (or trapezoids) with their base on the (0001) plane and their six walls formed on {1123} planes (Fig. 1a). In

  3. P-type poly-Si prepared by low-temperature aluminum-induced crystallization and doping for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Yasuhiro; Yu, Zhenrui; Morales-Acevedo, Arturo [CINVESTAV-IPN, Mexico, D.F. (Mexico)

    2000-07-01

    P-type poly-Si thin films prepared by low temperature aluminum-induced crystallization and doping are reported. The starting material was boron-doped a-Si:H prepared by PECVD on glass substrates. Aluminum layers with different thickness were evaporated on a-Si:H surface and conventional thermal annealing was performed at temperatures ranging from 300 to 550 Celsius degrees. XRD, SIMS, and Hall effect measurements were carried out to characterize the annealed Al could be crystallized at temperature as low as 300 Celsius degrees in 60 minutes. This material has high carrier concentration as well as high Hall mobility and can be used as a p-layer of seed layer for thin film poly-Si solar cells. The technique reported here is compatible with PECVD process. [Spanish] Se informa sobre la preparacion de peliculas delgadas tipo P y Poli-Si mediante la cristalizacion inducida de aluminio a baja temperatura y el dopado. El material inicial era de boro dopado y a-Si:H preparado PECVD sobre substratos de vidrio. Se evaporaron capas de aluminio de diferente espesor sobre una superficie de a-Si:H y se llevo a cabo un destemplado termico convencional a temperaturas que varian entre 300 y 500 grados Celsius. Se llevaron a cabo mediciones de XRB, SIMS y del efecto Hall para caracterizar el aluminio destemplado para que pudiera ser cristalizado a temperaturas tan bajas como 300 grados Celsius en 60 minutos. Este material tiene una alta concentracion portadora asi como una alta movilidad Hall y puede usarse como una capa de semilla para celdas solares de pelicula delgada Poli-Si. La tecnica reportada aqui es compatible con el proceso PECVD.

  4. Pristine and Al-doped hematite printed films as photoanodes of p-type dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Congiu, Mirko, E-mail: mirko.congiu@fc.unesp.br [UNESP–Univ. Estadual Paulista, POSMAT-Programa de Pós-Graduação em Ciência e Tecnologia de Materiais (Brazil); De Marco, Maria L.; Bonomo, Matteo [DC-FC-UNESP–Univ. Estadual Paulista (Brazil); Nunes-Neto, Oswaldo [UNESP–Univ. Estadual Paulista, POSMAT-Programa de Pós-Graduação em Ciência e Tecnologia de Materiais (Brazil); Dini, Danilo [DC-FC-UNESP–Univ. Estadual Paulista (Brazil); Graeff, Carlos F.O. [UNESP–Univ. Estadual Paulista, POSMAT-Programa de Pós-Graduação em Ciência e Tecnologia de Materiais (Brazil)

    2017-01-15

    We hereby propose a non-expensive method for the deposition of pure and Al-doped hematite photoanodes in the configuration of thin films for the application of dye-sensitized solar cells (DSSC). The electrodes have been prepared from hematite nanoparticles that were obtained by thermal degradation of a chemical precursor. The particles have been used in the preparation of a paste, suitable for both screen printing and doctor blade deposition. The paste was then spread on fluorine-doped tin oxide (FTO) to obtain porous hematite electrodes. The electrodes have been sensitized using N3 and D5 dyes and were characterized through current/voltage curves under simulated sun light (1 sun, AM 1.5) with a Pt counter electrode. Al-doping of hematite showed interesting changes in the physical and electrochemical characteristics of sensitized photoanodes since we could notice the growth of AlFe{sub 2}O{sub 4} (hercynite) as a secondary crystal phase into the oxides obtained by firing the mixtures of two chemical precursors at different molar ratios. Pure and Al-doped hematite electrodes have been used in a complete n-type DSSCs. The kinetics of charge transfer through the interface dye/electrolyte was studied and compared to that of a typical p-type DSSC based on NiO photocathodes sensitized with erythrosine B. The results suggest a potential application of both Fe{sub 2}O{sub 3} and Fe{sub 2}O{sub 3}/AlFe{sub 2}O{sub 4} as photoanodes of a tandem DSSC.

  5. The effect of doping on thermoelectric performance of p-type SnSe: Promising thermoelectric material

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Niraj Kumar; Bathula, Sivaiah; Gahtori, Bhasker [CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Tyagi, Kriti [CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Acdemy of Scientific and Innovative Research (AcSIR), CSIR-National Physical Laboratory (NPL) Campus, New Delhi (India); Haranath, D. [CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Dhar, Ajay, E-mail: adhar@nplindia.org [CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India)

    2016-05-25

    Tin selenide (SnSe) based thermoelectric materials are being explored for making inexpensive and efficient thermoelectric devices with improved thermoelectric efficiency. As both Sn and Se are earth abundant and relatively inexpensive and these alloys do not involve toxic materials, such as lead and expensive tellurium. Hence, in the present study, we have synthesized SnSe doped with 2 at% of aluminium (Al), lead (Pb), indium (In) and copper (Cu) individually, which is not reported in literature. Out of these, Cu doped SnSe resulted in enhancement of figure-of-merit (zT) of ∼0.7 ± 0.02 at 773 K, synthesized employing conventional fusion method followed by spark plasma sintering. This enhancement in zT is ∼16% over the existing state-of-the-art value for p-type SnSe alloy doped with expensive Ag. This enhancement in ZT is primarily due to the presence of Cu{sub 2}Se second phase associated with intrinsic nanostructure formation of SnSe. This enhancement has been corroborated with the microstructural characterization using field emission scanning electron microscopy and X-ray diffraction studies. Also, Cu doped SnSe exhibited a higher value of carrier concentration in comparison to other samples doped with Al, Pb and In. Further, the compatibility factor of Cu doped SnSe alloys exhibited value of 1.62 V{sup −1} at 773 K and it is suitable to segment with most of the novel TE materials for obtaining the higher thermoelectric efficiencies. - Highlights: • Tin selenide (SnSe) doped with non-toxic and inexpensive dopants. • Synthesized highly dense SnSe employing Spark plasma sintering. • Enhanced thermoelectric compatibility factor of SnSe. • Enhanced thermoelectric performance of SnSe doped with Copper.

  6. p-Type Transparent Conducting Oxide/n-Type Semiconductor Heterojunctions for Efficient and Stable Solar Water Oxidation.

    Science.gov (United States)

    Chen, Le; Yang, Jinhui; Klaus, Shannon; Lee, Lyman J; Woods-Robinson, Rachel; Ma, Jie; Lum, Yanwei; Cooper, Jason K; Toma, Francesca M; Wang, Lin-Wang; Sharp, Ian D; Bell, Alexis T; Ager, Joel W

    2015-08-05

    Achieving stable operation of photoanodes used as components of solar water splitting devices is critical to realizing the promise of this renewable energy technology. It is shown that p-type transparent conducting oxides (p-TCOs) can function both as a selective hole contact and corrosion protection layer for photoanodes used in light-driven water oxidation. Using NiCo2O4 as the p-TCO and n-type Si as a prototypical light absorber, a rectifying heterojunction capable of light driven water oxidation was created. By placing the charge separating junction in the Si using a np(+) structure and by incorporating a highly active heterogeneous Ni-Fe oxygen evolution catalyst, efficient light-driven water oxidation can be achieved. In this structure, oxygen evolution under AM1.5G illumination occurs at 0.95 V vs RHE, and the current density at the reversible potential for water oxidation (1.23 V vs RHE) is >25 mA cm(-2). Stable operation was confirmed by observing a constant current density over 72 h and by sensitive measurements of corrosion products in the electrolyte. In situ Raman spectroscopy was employed to investigate structural transformation of NiCo2O4 during electrochemical oxidation. The interface between the light absorber and p-TCO is crucial to produce selective hole conduction to the surface under illumination. For example, annealing to produce more crystalline NiCo2O4 produces only small changes in its hole conductivity, while a thicker SiOx layer is formed at the n-Si/p-NiCo2O4 interface, greatly reducing the PEC performance. The generality of the p-TCO protection approach is demonstrated by multihour, stable, water oxidation with n-InP/p-NiCo2O4 heterojunction photoanodes.

  7. Hadron-therapy beam monitoring: Towards a new generation of ultra-thin p-type silicon strip detectors

    International Nuclear Information System (INIS)

    Bouterfa, M.; Aouadi, K.; Bertrand, D.; Olbrechts, B.; Delamare, R.; Raskin, J. P.; Gil, E. C.; Flandre, D.

    2011-01-01

    Hadron-therapy has gained increasing interest for cancer treatment especially within the last decade. System commissioning and quality assurance procedures impose to monitor the particle beam using 2D dose measurements. Nowadays, several monitoring systems exist for hadron-therapy but all show a relatively high influence on the beam properties: indeed, most devices consist of several layers of materials that degrade the beam through scattering and energy losses. For precise treatment purposes, ultra-thin silicon strip detectors are investigated in order to reduce this beam scattering. We assess the beam size increase provoked by the Multiple Coulomb Scattering when passing through Si, to derive a target thickness. Monte-Carlo based simulations show a characteristic scattering opening angle lower than 1 mrad for thicknesses below 20 μm. We then evaluated the fabrication process feasibility. We successfully thinned down silicon wafers to thicknesses lower than 10 μm over areas of several cm 2 . Strip detectors are presently being processed and they will tentatively be thinned down to 20 μm. Moreover, two-dimensional TCAD simulations were carried out to investigate the beam detector performances on p-type Si substrates. Additionally, thick and thin substrates have been compared thanks to electrical simulations. Reducing the pitch between the strips increases breakdown voltage, whereas leakage current is quite insensitive to strips geometrical configuration. The samples are to be characterized as soon as possible in one of the IBA hadron-therapy facilities. For hadron-therapy, this would represent a considerable step forward in terms of treatment precision. (authors)

  8. A New Approach to the Computer Modeling of Amorphous Nanoporous Structures of Semiconducting and Metallic Materials: A Review

    Science.gov (United States)

    Romero, Cristina; Noyola, Juan C.; Santiago, Ulises; Valladares, Renela M.; Valladares, Alexander; Valladares, Ariel A.

    2010-01-01

    We review our approach to the generation of nanoporous materials, both semiconducting and metallic, which leads to the existence of nanopores within the bulk structure. This method, which we have named as the expanding lattice method, is a novel transferable approach which consists first of constructing crystalline supercells with a large number of atoms and a density close to the real value and then lowering the density by increasing the volume. The resulting supercells are subjected to either ab initio or parameterized—Tersoff-based—molecular dynamics processes at various temperatures, all below the corresponding bulk melting points, followed by geometry relaxations. The resulting samples are essentially amorphous and display pores along some of the “crystallographic” directions without the need of incorporating ad hoc semiconducting atomic structural elements such as graphene-like sheets and/or chain-like patterns (reconstructive simulations) or of reproducing the experimental processes (mimetic simulations). We report radial (pair) distribution functions, nanoporous structures of C and Si, and some computational predictions for their vibrational density of states. We present numerical estimates and discuss possible applications of semiconducting materials for hydrogen storage in potential fuel tanks. Nanopore structures for metallic elements like Al and Au also obtained through the expanding lattice method are reported.

  9. A very general rate expression for charge hopping in semiconducting polymers

    Energy Technology Data Exchange (ETDEWEB)

    Fornari, Rocco P.; Aragó, Juan; Troisi, Alessandro [Department of Chemistry and Centre for Scientific Computing, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2015-05-14

    We propose an expression of the hopping rate between localized states in semiconducting disordered polymers that contain the most used rates in the literature as special cases. We stress that these rates cannot be obtained directly from electron transfer rate theories as it is not possible to define diabatic localized states if the localization is caused by disorder, as in most polymers, rather than nuclear polarization effects. After defining the separate classes of accepting and inducing nuclear modes in the system, we obtain a general expression of the hopping rate. We show that, under the appropriate limits, this expression reduces to (i) a single-phonon rate expression or (ii) the Miller-Abrahams rate or (iii) a multi-phonon expression. The description of these limits from a more general expression is useful to interpolate between them, to validate the assumptions of each limiting case, and to define the simplest rate expression that still captures the main features of the charge transport. When the rate expression is fed with a range of realistic parameters the deviation from the Miller-Abrahams rate is large or extremely large, especially for hopping toward lower energy states, due to the energy gap law.

  10. Structural studies of thin films of semiconducting nanoparticles in polymer matrices

    International Nuclear Information System (INIS)

    Di Luccio, Tiziana; Piscopiello, Emanuela; Laera, Anna Maria; Antisari, Marco Vittori

    2007-01-01

    Ordered films of nanoscale materials are issue of wide interest for applications in several fields, such as optics, catalysis, and bioelectronics. In particular, semiconducting nanoparticles incorporation in a processable polymer film is an easy way to manipulate such materials for their application. We deposited thin layers of cadmium sulphide (CdS) and zinc sulphide (ZnS) nanoparticles embedded in a thermoplastic cyclo-olephin copolymer (COC) with elevated optical transparency and highly bio-compatible. The nanoparticles were obtained by thiolate precursors previously dispersed in the polymer upon thermal treatment at temperatures ranging between 200 and 300 deg. C depending on the desired size. The precursor/polymer solutions were spin-coated in order to get thin films. The spinning conditions were changed in order to optimise the layer thickness and uniformity. The samples were mainly characterised by X-ray reflectivity (XRR) and by high-resolution transmission electron microscopy (HRTEM) analyses. The thinnest layer we have deposited is 8 nm thick, as evaluated by XRR. The HRTEM measurements showed that the nanoparticles have quasi-spherical shape without evident microstructural defects. The size of the nanoparticles depends on the annealing temperature, e.g. at 232 deg. C the size of the CdS nanoparticles is about 4-5 nm

  11. Electronic structure and optical spectra of semiconducting carbon nanotubes functionalized by diazonium salts

    Science.gov (United States)

    Ramirez, Jessica; Mayo, Michael L.; Kilina, Svetlana; Tretiak, Sergei

    2013-02-01

    We report density functional (DFT) calculations on finite-length semiconducting carbon nanotubes covalently and non-covalently functionalized by aryl diazonium moieties and their chlorinated derivatives. For these systems, we investigate (i) an accuracy of different functionals and basis sets, (ii) a solvent effect, and (iii) the impact of the chemical functionalization on optical properties of nanotubes. In contrast to B3LYP, only long-range-corrected functionals, such as CAM-B3LYP and wB97XD, properly describe the ground and excited state properties of physisorbed molecules. We found that physisorbed cation insignificantly perturbs the optical spectra of nanotubes. In contrast, covalently bound complexes demonstrate strong redshifts and brightening of the lowest exciton that is optically dark in pristine nanotubes. However, the energy and oscillator strength of the lowest state are dictated by the position of the molecule on the nanotube. Thus, if controllable and selective chemical functionalization is realized, the PL of nanotubes could be improved.

  12. Elaboration of a semiconductive thin film device technology on the basis of monocrystalline gallium arsenide

    International Nuclear Information System (INIS)

    Antoshenko, V.; Taurbaev, T.; Skirnevskaya, E.; Shorin, V.; Mihajlov, L.; Bajganatova, Sh.

    1996-01-01

    The aim of the project: To elaborate the economical technological process of preparing super thin monocrystalline GaAs substrates and device structures for semiconductive electronics. To realize the project it is necessary to solve following problems: o to elaborate and produce the equipment for preparing of separated films and thin film multilayer structures with p-n-junction; - to study conditions of preparing plane crystal perfect separated Ga(Al)As - films; - to optimize regimes of preparing thin film structures with p- and n-conductive - layers; - to determine the optimal methods of transferring autonomous films and structures over the second substrates; - to work out preparing methods of ohmic contacts and electrical commutation; - to optimize the process of repeated use of initial monocrystalline GaAs substrate; - to prepare the samples of discrete thin film photo- and emitting devices. As the result of project realization there will be created cheap ecological technology of heterojunction optoelectronic devices on the basis of GaAs and AlGaAs solid solutions, the laboratory samples of thin film devices will be presented

  13. Tailoring graphene-based electrodes from semiconducting to metallic to increase the energy density in supercapacitors

    Science.gov (United States)

    Vatamanu, Jenel; Ni, Xiaojuan; Liu, Feng; Bedrov, Dmitry

    2015-11-01

    The semiconducting character of graphene and some carbon-based electrodes can lead to noticeably lower total capacitances and stored energy densities in electric double layer (EDL) capacitors. This paper discusses the chemical and electronic structure modifications that enhance the available energy bands, density of states and quantum capacitance of graphene substrates near the Fermi level, therefore restoring the conducting character of these materials. The doping of graphene with p or n dopants, such as boron and nitrogen atoms, or the introduction of vacancy defects that introduce zigzag edges, can significantly increase the quantum capacitance within the potential range of interest for the energy storage applications by either shifting the Dirac point away from the Fermi level or by eliminating the Dirac point. We show that a combination of doping and vacancies at realistic concentrations is sufficient to increase the capacitance of a graphene-based electrode to within 1 μF cm-2 from that of a metallic surface. Using a combination of ab initio calculations and classical molecular dynamics simulations we estimate how the changes in the quantum capacitance of these electrode materials affect the total capacitance stored by the open structure EDL capacitors containing room temperature ionic liquid electrolytes.

  14. Fabrication of an organic field effect transistor using nano imprinting of Ag inks and semiconducting polymers

    International Nuclear Information System (INIS)

    Hu, PingAn; Li, Kun; O'Neill, William; Chen, Weilin; Peng, Li; Chu, Daping

    2010-01-01

    A simple and cheap procedure for flexible electronics fabrication was demonstrated by imprinting metallic nanoparticles (NPs) on flexible substrates. Silver NPs with an average diameter of 10 nm were prepared via an improved chemical approach and Ag Np ink was produced in α-terpineol with a concentration up to 15%. Silver micro/nanostructures with a dimension varying from nanometres to microns were produced on a flexible substrate (polyimide) by imprinting the as-prepared silver ink. The fine fluidic properties of an Ag NP/α-terpineol solution and low melting temperatures of silver nanoparticles render a low pressure and low temperature procedure, which is well suited for flexible electronics fabrication. The effects of sintering and mechanical bending on the conductivity of imprinted silver contacts were also investigated. Large area organic field effect transistors (OFET) on flexible substrates were fabricated using an imprinted silver electrode and semiconducting polymer. The OFET with silver electrodes imprinted from our prepared oleic acid stabilized Ag nanoparticle ink show an ideal ohmic contact; therefore, the OFET exhibit high performance (I on /I off ratio: 1 × 10 3 ; mobility: 0.071 cm 2 V −1 s −1 ).

  15. Photoproduction of I2, Br2, and Cl2 on n-semiconducting powder

    Science.gov (United States)

    Reichman, B.; Byvik, C. E.

    1981-01-01

    The photosynthetic production of Br2 and Cl2 and the photocatalytic production of I2 from aqueous solutions of the respective halide ions in the presence of platinized semiconducting n-TiO2 powder are reported. Reactions were produced in 2-3 M oxygen-saturated aqueous solutions of KI, KBr or NaCl containing Pt-TiO2 powder which were irradiated by a high-pressure mercury lamp at a power of 400 mW/sq cm. Halogens are found to be produced in greater quantities when platinized TiO2 powders are used rather than pure TiO2, and rates of halogen production are observed to increase from Cl2 to Br2 to I2. The presence of the synthetic reactions producing Br2 and Cl2 with a net influx of energy indicates that an effective separation of the photoproduced electron-hole pair occurs in the semiconductor. Quantum efficiencies of the reaction, which increase with decreasing solution pH, are found to be as high as 30%, implying a solar-to-chemical energy conversion efficiency between 0.03% and 3% for the case of chlorine production. It is concluded that the photoproduction of halogens may be of practical value if product halogens are efficiently removed from the reaction cell.

  16. Semiconducting polymer-incorporated nanocrystalline TiO2 particles for photovoltaic applications

    International Nuclear Information System (INIS)

    Peng Fuguo; Wu Jihuai; Li Qingbei; Wang Yue; Yue Gentian; Xiao Yaoming; Li Qinghua; Lan Zhang; Fan Leqing; Lin Jianming; Huang Miaoliang

    2011-01-01

    Highlights: → A P3HT-PCBM/TiO 2 trinary hybrid solar cell has been fabricated. → P3HT-PCBM heterojunction replaces the dye and electrolyte in dye-sensitized cell, → Which simplifies preparation procedure and decreases the device cost. → The hybrid cell achieves a light-to-electric conversion efficiency of 2.61%. - Abstract: In this work, we study hybrid solar cells based on blends of the semiconducting polymer poly(3-octylthiophene-2,5-diyl)(P3OT) and [6,6]-phenyl C 61 butyric acid methyl (PCBM) coated titanium dioxide (TiO 2 ) nanocrystal film. The Fourier transform infrared spectra (FTIR), UV-vis absorption spectra and PL quenching researches show that the films had a stronger absorption in visible light range. The influence of the PCBM:P3OT ratio were researched and the optimized ratio of PCBM to P3OT (1:1.5) exhibit a short circuit current of 4.42 mA cm -2 , an open circuit voltage of 0.81 V, a fill factor of 0.73 and a light-to-electric conversion efficiency of 2.61% under a simulated solar light irradiation of 100 mW cm -2 .

  17. pH and Protein Sensing with Functionalized Semiconducting Oxide Nanobelt FETs

    Science.gov (United States)

    Cheng, Yi; Yun, C. S.; Strouse, G. F.; Xiong, P.; Yang, R. S.; Wang, Z. L.

    2008-03-01

    We report solution pH sensing and selective protein detection with high-performance channel-limited field-effect transistors (FETs) based on single semiconducting oxide (ZnO and SnO2) nanobelts^1. The devices were integrated with PDMS microfluidic channels for analyte delivery and the source/drain contacts were passivated for in-solution sensing. pH sensing experiments were performed on FETs with functionalized and unmodified nanobelts. Functionalization of the nanobelts by APTES was found to greatly improve the pH sensitivity. The change in nanobelt conductance as functions of pH values at different gate voltages and ionic strengths showed high sensitivity and consistency. For the protein detection, we achieved highly selective biotinylation of the nanobelt channel with through APTES linkage. The specific binding of fluorescently-tagged streptavidin to the biotinylated nanobelt was verified by fluorescence microscopy; non-specific binding to the substrate was largely eliminated using PEG-silane passivation. The electrical responses of the biotinylated FETs to the streptavidin binding in PBS buffers of different pH values were systematically measured. The results will be presented and discussed. ^1Y. Cheng et al., Appl. Phys. Lett. 89, 093114 (2006). *Supported by NSF NIRT Grant ECS-0210332.

  18. Contaminant degradation by irradiated semiconducting silver chloride particles: kinetics and modelling.

    Science.gov (United States)

    Ma, Tian; Garg, Shikha; Miller, Christopher J; Waite, T David

    2015-05-15

    The kinetics and mechanism of light-mediated formic acid (HCOO(-)) degradation in the presence of semiconducting silver chloride particles are investigated in this study. Our experimental results show that visible-light irradiation of AgCl(s) results in generation of holes and electrons with the photo-generated holes and its initial oxidation product carbonate radical, oxidizing HCOO(-) to form CO2. The HCOO(-) degradation rate increases with increase in silver concentration due to increase in rate of photo-generation of holes while the increase in chloride concentration decreases the degradation rate of HCOO(-) as a result of the scavenging of holes by Cl(-), thereby resulting in decreased holes and carbonate radical concentration. The results obtained indicate that a variety of other solution conditions including dioxygen concentration, bicarbonate concentration and pH influence the availability of holes and hence the HCOO(-) degradation rate in a manner consistent with our understanding of key processes. Based on our experimental results, we have developed a kinetic model capable of predicting AgCl(s)-mediated HCOO(-) photo-degradation over a wide range of conditions. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Thermal conductivity of organic semi-conducting materials using 3omega and photothermal radiometry techniques

    Directory of Open Access Journals (Sweden)

    Reisdorffer Frederic

    2014-01-01

    Full Text Available Organic semiconductors for opto-electronic devices show several defects which can be enhanced while increasing the operating temperature. Their thermal management and especially the reduction of their temperature are of great interest. For the heat transfer study, one has to measure the thermal conductivity of thin film organic materials. However the major difficulty for this measurement is the very low thickness of the films which needs the use of very specific techniques. In our work, the 3-omega and photothermal radiometric methods were used to measure the thermal conductivity of thin film organic semiconducting material (Alq3. The measurements were performed as function of the thin film thickness from 45 to 785 nm and also of its temperature from 80 to 350 K. With the 3 omega method, a thermal conductivity value of 0.066 W.m−1K−1 was obtained for Alq3 thin film of 200 nm at room temperature, in close agreement with the photothermal value. Both techniques appear to be complementary: the 3 omega method is easier to implement for large temperature range and small thicknesses down to a few tens of nanometers whereas the photothermal method is more suitable for thicknesses over 200nm since it provides additional information such as the thin film volumetric heat capacity.

  20. Radiation-Hard Complementary Integrated Circuits Based on Semiconducting Single-Walled Carbon Nanotubes.

    Science.gov (United States)

    McMorrow, Julian J; Cress, Cory D; Gaviria Rojas, William A; Geier, Michael L; Marks, Tobin J; Hersam, Mark C

    2017-03-28

    Increasingly complex demonstrations of integrated circuit elements based on semiconducting single-walled carbon nanotubes (SWCNTs) mark the maturation of this technology for use in next-generation electronics. In particular, organic materials have recently been leveraged as dopant and encapsulation layers to enable stable SWCNT-based rail-to-rail, low-power complementary metal-oxide-semiconductor (CMOS) logic circuits. To explore the limits of this technology in extreme environments, here we study total ionizing dose (TID) effects in enhancement-mode SWCNT-CMOS inverters that employ organic doping and encapsulation layers. Details of the evolution of the device transport properties are revealed by in situ and in operando measurements, identifying n-type transistors as the more TID-sensitive component of the CMOS system with over an order of magnitude larger degradation of the static power dissipation. To further improve device stability, radiation-hardening approaches are explored, resulting in the observation that SWNCT-CMOS circuits are TID-hard under dynamic bias operation. Overall, this work reveals conditions under which SWCNTs can be employed for radiation-hard integrated circuits, thus presenting significant potential for next-generation satellite and space applications.