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Sample records for p-type modulation doping

  1. Electronic transport in n- and p-type modulation doped Ga{sub x}In{sub 1-x}N{sub y}As{sub 1-y}/ GaAs quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Y; Balkan, N [School of Computer Science and Electronic Engineering, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (United Kingdom); Aslan, M; Arikan, M C [Faculty of Science, Department of Physics, Istanbul University, 34134 Istanbul (Turkey); Lisesivdin, S B [Department of Physics, Faculty of Science and Arts, Gazi University, Teknikokullar, 06500 Ankara (Turkey); Carrere, H; Marie, X [Department of Physics, INSA, 135 avenue de Rangeil, 31077 Toulouse cedex 4 (France)], E-mail: balkan@essex.ac.uk

    2009-04-29

    We present a comprehensive study of longitudinal transport of two-dimensional (2D) carriers in n- and p-type modulation doped Ga{sub x}In{sub 1-x}N{sub y}As{sub 1-y} /GaAs quantum well structures. The Hall mobility and carrier density of electrons in the n-modulation doped quantum wells (QWs) decreases with increasing nitrogen composition. However, the mobility of the 2D holes in p-modulation doped wells is not influenced by nitrogen and it is significantly higher than that of 2D electrons in n-modulation doped material. The observed behaviour is explained in terms of increasing electron effective mass as well as enhanced N-related alloying scattering with increasing nitrogen content. In order to determine the conduction band (CB) and valence band (VB) structures as well as electron and hole effective masses, the band anticrossing model with an eight-band k.p approximation in the Luettinger-Kohn approach is used. The effects of strain, quantum confinement and the strong coupling between the localized nitrogen states and the CB extended states of GaInAs are considered in the calculations. The results indicate that the nitrogen induces a strong perturbation to the CB of the matrix semiconductor whilst the VB remains unaffected. The temperature dependent mobility of 2D electron gas is discussed using an analytical model that accounts for the most important scattering mechanisms. The results indicate that the interface roughness and N-related alloy scattering are the dominant mechanisms at low temperatures, while polar optical phonon and N-related alloy scattering limit mobility at high temperatures.

  2. Development in p-type Doping of ZnO

    Institute of Scientific and Technical Information of China (English)

    YU Liping; ZHU Qiqiang; FAN Dayong; LAN Zili

    2012-01-01

    Zinc oxide (ZnO) is a wide band-gap material of the Ⅱ-Ⅵ group with excellent optical properties for optoelectronics applications,such as the flat panel displays and solar cells used in sports tournament.Despite its advantages,the application of ZnO is hampered by the lack of stable p-type doping.In this paper,the recent progress in this field was briefly reviewed,and a comprehensive summary of the research was carried out on ZnO fabrication methods and its electrical,optical,and magnetic properties were presented.

  3. Bi-Se doped with Cu, p-type semiconductor

    Science.gov (United States)

    Bhattacharya, Raghu Nath; Phok, Sovannary; Parilla, Philip Anthony

    2013-08-20

    A Bi--Se doped with Cu, p-type semiconductor, preferably used as an absorber material in a photovoltaic device. Preferably the semiconductor has at least 20 molar percent Cu. In a preferred embodiment, the semiconductor comprises at least 28 molar percent of Cu. In one embodiment, the semiconductor comprises a molar percentage of Cu and Bi whereby the molar percentage of Cu divided by the molar percentage of Bi is greater than 1.2. In a preferred embodiment, the semiconductor is manufactured as a thin film having a thickness less than 600 nm.

  4. Ultraviolet light-emitting diodes with polarization-doped p-type layer

    Science.gov (United States)

    Hu, Wenxiao; Qin, Ping; Song, Weidong; Zhang, Chongzhen; Wang, Rupeng; Zhao, Liangliang; Xia, Chao; Yuan, Songyang; Yin, Yian; Li, Shuti

    2016-09-01

    We report ultraviolet light emitting diode (LEDs) with polarization doped p-type layer. Fabricated LEDs with polarization doped p-type layer exhibited reduced forward voltage and enhanced light output power, compared to those with traditional p-type AlGaN layer. The improvement is attributed to improved hole concentration and the smooth valence band by the polarization enhanced p-type doping. Our simulated results reveal that this p-type layer can further enhance the performance of ultraviolet LEDs by removing the electron blocking layer (EBL).

  5. Luminance behavior of lithium-doped ZnO nanowires with p-type conduction characteristics.

    Science.gov (United States)

    Ko, Won Bae; Lee, Jun Seok; Lee, Sang Hyo; Cha, Seung Nam; Sohn, Jung Inn; Kim, Jong Min; Park, Young Jun; Kim, Hyun Jung; Hong, Jin Pyo

    2013-09-01

    The present study describes the room-temperature cathodeluminescence (CL) and temperature-dependent photoluminescence (PL) properties of p-type lithium (Li)-doped zinc oxide (ZnO) nanowires (NWs) grown by hydrothermal doping and post-annealing processes. A ZnO thin film was used as a seed layer in NW growth. The emission wavelengths and intensities of undoped ZnO NWs and p-type Li-doped ZnO NWs were analyzed for comparison. CL and PL observations of post-annealed p-type Li-doped ZnO NWs clearly exhibited a dominant sharp band-edge emission. Finally, a n-type ZnO thin film/p-type annealed Li-doped ZnO NW homojunction diode was prepared to confirm the p-type conduction of annealed Li-doped ZnO NWs as well as the structural properties measured by transmission electron microscopy.

  6. 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.

  7. 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.

  8. Theoretical prediction of p-type transparent conductivity in Zn-doped TiO2.

    Science.gov (United States)

    Han, Xiaoping; Shao, Guosheng

    2013-06-28

    It is very difficult and yet extremely important to fill the wide technological gap in developing transparent conducting oxides (TCOs) that exhibit excellent p-type conducting characteristics. Here, on the basis of extensive first-principles calculations, we discover for the first time potentially promising p-type transparent conductivity in Zn-doped TiO2 under oxygen rich conditions. Efforts have been made to elaborate the effects of possible defects and their interaction with Zn doping on the p-type transparent conductivity. This work offers a fundamental road map for cost-effective development of p-type TCOs based on TiO2, which is a cheap and stable material system of large natural resources.

  9. Fabrication of p-type lithium niobate crystals by molybdenum doping and polarization

    Science.gov (United States)

    Tian, Tian; Kong, Yongfa; Liu, Hongde; Liu, Shiguo; Li, Wei; Chen, Shaolin; Xu, Jiayue

    2017-06-01

    The lack of p-type lithium niobate limits it serving as an active material. A series of Mo-doped and pure congruent lithium niobate crystals were grown by Czochralski method under different polarization conditions. Their dominant carrier species were characterized by holographic experiment. The results showed dominant charge carrier species may be changed from electrons to holes when lithium niobate crystal was doped with Mo ions and polarized under the current of 70mA for 30 minutes. It indicated that p-type lithium niobate crystal could be fabricated by Mo-doping and suitably controlling the polarization condition. Mo-doped lithium niobate crystals can be a promising candidate for active components.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Effective p-type N-doped WS{sub 2} monolayer

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xu, E-mail: zhaoxu@htu.cn; Xia, Congxin; Wang, Tianxing; Peng, Yuting; Dai, Xianqi

    2015-11-15

    Based on density functional theory, the characteristics of n- and p-type dopants are investigated by means of group V and VII atoms substituting sulfur in the WS{sub 2} monolayer. Numerical results show that for each doping case, the formation energy is lower under W-rich condition, which indicates that it is energy favorable to incorporate group V and VII atoms into WS{sub 2} under W-rich experimental conditions. Moreover, compared with other dopant cases, N-doped WS{sub 2} monolayer owns the lowest formation energy. In particular, the transition level of (−1/0) is only 75 meV in the N-doped case, which indicates that N impurities can offer effective p-type carriers in the WS{sub 2} monolayer. - Highlights: • The formation energy is lower under W-rich conditions. • N-doped system owns the lowest formation energy compared with other atoms. • The transition level of N-doping in WS{sub 2} is 75 meV. • N impurities can offer effective p-type carriers in the WS{sub 2}.

  12. p-Type MWT. Integrated cell and module technology

    Energy Technology Data Exchange (ETDEWEB)

    Tool, C.J.J.; Kossen, E.J.; Bennett, I.J.

    2013-10-15

    A major issue of concern in MWT solar cells is the increased leakage current at reversed bias voltage through the vias compared. At ECN we have been working on reducing this leakage current to levels comparable to H-pattern cells. In this study we present the results of this work. We further show the benefit of a combined cell and module design for MWT solar cells. At the cell level, MWT production costs per wafer are comparable with H-pattern while the cell output increases. At the module level this design results in a further increase of the power output.

  13. p-type MWT. Integrated Cell and Module Technology

    Energy Technology Data Exchange (ETDEWEB)

    Tool, C.J.J.; Kossen, E.J.; Bennett, I.J. [ECN Solar Energy, Petten (Netherlands)

    2013-03-15

    A major issue of concern in MWT (metal wrap-through) solar cells is the increased leakage current at reversed bias voltage through the vias compared. At ECN we have been working on reducing this leakage current to levels comparable to H-pattern cells. In this study we present the results of this work. We further show the benefit of a combined cell and module design for MWT solar cells. At the cell level, MWT production costs per wafer are comparable with H-pattern while the cell output increases. At the module level this design results in a further increase of the power output.

  14. Infrared absorption and visible transparency in heavily doped p-type BaSnO3

    Science.gov (United States)

    Li, Yuwei; Sun, Jifeng; Singh, David J.

    2017-01-01

    The recent experimental work shows that perovskite BaSnO3 can be heavily doped by K to become a stable p-type semiconductor. Here, we find that p-type perovskite BaSnO3 retains transparency for visible light while absorbing strongly in the infrared below 1.5 eV. The origin of the remarkable optical transparency even with heavy doping is that the interband transitions that are enabled by empty states at the top of the valence band are concentrated mainly in the energy range from 0.5 to 1.5 eV, i.e., not extending past the near IR. In contrast to n-type, the Burstein-Moss shift is slightly negative, but very small reflecting the heavier valence bands relative to the conduction bands.

  15. Electrical band-gap narrowing in n- and p-type heavily doped silicon at 300 K

    Science.gov (United States)

    Van Cong, H.; Brunet, S.

    1986-09-01

    Based on previous results band-gap narrowing in heavily doped silicon at 300 K is investigated and expressed in terms of impurity size-and-doping effects. The results obtained for n- and p-type heavily doped silicon are compared with other theories and experiments.

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

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

    High-quality p-type boron-doped II0b 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.

  17. 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.

  18. Few-Layer MoS₂ p-Type Devices Enabled by Selective Doping Using Low Energy Phosphorus Implantation.

    Science.gov (United States)

    Nipane, Ankur; Karmakar, Debjani; Kaushik, Naveen; Karande, Shruti; Lodha, Saurabh

    2016-02-23

    P-type doping of MoS2 has proved to be a significant bottleneck in the realization of fundamental devices such as p-n junction diodes and p-type transistors due to its intrinsic n-type behavior. We report a CMOS compatible, controllable and area selective phosphorus plasma immersion ion implantation (PIII) process for p-type doping of MoS2. Physical characterization using SIMS, AFM, XRD and Raman techniques was used to identify process conditions with reduced lattice defects as well as low surface damage and etching, 4X lower than previous plasma based doping reports for MoS2. A wide range of nondegenerate to degenerate p-type doping is demonstrated in MoS2 field effect transistors exhibiting dominant hole transport. Nearly ideal and air stable, lateral homogeneous p-n junction diodes with a gate-tunable rectification ratio as high as 2 × 10(4) are demonstrated using area selective doping. Comparison of XPS data from unimplanted and implanted MoS2 layers shows a shift of 0.67 eV toward lower binding energies for Mo and S peaks indicating p-type doping. First-principles calculations using density functional theory techniques confirm p-type doping due to charge transfer originating from substitutional as well as physisorbed phosphorus in top few layers of MoS2. Pre-existing sulfur vacancies are shown to enhance the doping level significantly.

  19. 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.

  20. p-Type hydrogen sensing with Al- and V-doped TiO2 nanostructures

    Science.gov (United States)

    Li, Zhaohui; Ding, Dongyan; Ning, Congqin

    2013-01-01

    Doping with other elements is one of the efficient ways to modify the physical and chemical properties of TiO2 nanomaterials. In the present work, anatase TiO2 nanofilms doped with Al and V elements were fabricated through anodic oxidation of Ti6Al4V alloy and further annealing treatment. Hydrogen sensing behavior of the crystallized Ti-Al-V-O nanofilms at various working temperatures was investigated through exposure to 1,000 ppm H2. Different from n-type hydrogen sensing characteristics of undoped TiO2 nanotubes, the Al- and V-doped nanofilms presented a p-type hydrogen sensing behavior by showing increased resistance upon exposure to the hydrogen-containing atmosphere. The Ti-Al-V-O nanofilm annealed at 450°C was mainly composed of anatase phase, which was sensitive to hydrogen-containing atmosphere only at elevated temperatures. Annealing of the Ti-Al-V-O nanofilm at 550°C could increase the content of anatase phase in the oxide nanofilm and thus resulted in a good sensitivity and resistance recovery at both room temperature and elevated temperatures. The TiO2 nanofilms doped with Al and V elements shows great potential for use as a robust semiconducting hydrogen sensor.

  1. Increased Photoconductivity Lifetime in GaAs Nanowires by Controlled n-Type and p-Type Doping.

    Science.gov (United States)

    Boland, Jessica L; Casadei, Alberto; Tütüncüoglu, Gözde; Matteini, Federico; Davies, Christopher L; Jabeen, Fauzia; Joyce, Hannah J; Herz, Laura M; Fontcuberta I Morral, Anna; Johnston, Michael B

    2016-04-26

    Controlled doping of GaAs nanowires is crucial for the development of nanowire-based electronic and optoelectronic devices. Here, we present a noncontact method based on time-resolved terahertz photoconductivity for assessing n- and p-type doping efficiency in nanowires. Using this technique, we measure extrinsic electron and hole concentrations in excess of 10(18) cm(-3) for GaAs nanowires with n-type and p-type doped shells. Furthermore, we show that controlled doping can significantly increase the photoconductivity lifetime of GaAs nanowires by over an order of magnitude: from 0.13 ns in undoped nanowires to 3.8 and 2.5 ns in n-doped and p-doped nanowires, respectively. Thus, controlled doping can be used to reduce the effects of parasitic surface recombination in optoelectronic nanowire devices, which is promising for nanowire devices, such as solar cells and nanowire lasers.

  2. Study of p-type AlN-doped SnO2 thin films and its transparent devices

    Science.gov (United States)

    Wu, Y. J.; Liu, Y. S.; Hsieh, C. Y.; Lee, P. M.; Wei, Y. S.; Liao, C. H.; Liu, C. Y.

    2015-02-01

    The electrical properties of transparent Al-doped tin oxide (SnO2), N-doped SnO2, and AlN-doped SnO2 thin films were studied. The Al-doped tin oxide (SnO2) thin films all show n-type conduction regardless the annealing condition. The n-type conduction of the as-deposited N-doped SnO2, and AlN-doped SnO2 thin films could be converted to p-type conduction by annealing the films at an elevated temperature of 450 °C. XPS analysis verified that the substitution of N ions in the O ion sites in the annealed N-doped SnO2 and AlN-doped SnO2 thin films were responsible for the n-p conduction transition. The conduction of the annealed N-doped SnO2 and AlN-doped SnO2 thin films could be converted back to n-type conduction by thermally annealing the films at higher temperature, over 450 °C. The p-n conduction transition is related with the outgassing of N ions in the p-type N-doped SnO2 and AlN-doped SnO2 thin films. Remarkably, we found that the Al content can retard the outgassing of N ions in the p-type N-doped SnO2 and AlN-doped SnO2 thin films and prolong the p-n conduction transition temperature above 600 °C. XPS analysis revealed that the formation of the Snsbnd Nsbnd Al bond improved the stability of the N ions in the AlN-doped SnO2 thin films. I-V curve of the p-type AlN-doped SnO2/n-type fluorine-doped SnO2 junction exhibited clear p-n junction characteristics, a low leakage current under the revised bias (1.13 × 10-5 A at -5 V), and a low turn-on voltage (3.24 V). p-Type AlN-doped SnO2/n-type fluorine-doped SnO2 junction exhibited excellent transmittance (over 90%) in the visible region (470-750 nm).

  3. P-type nitrogen-doped ZnO nanostructures with controlled shape and doping level by facile microwave synthesis.

    Science.gov (United States)

    Herring, Natalie P; Panchakarla, Leela S; El-Shall, M Samy

    2014-03-04

    We report herein the development of a facile microwave irradiation (MWI) method for the synthesis of high-quality N-doped ZnO nanostructures with controlled morphology and doping level. We present two different approaches for the MWI-assisted synthesis of N-doped ZnO nanostructures. In the first approach, N-doping of Zn-poor ZnO prepared using zinc peroxide (ZnO2) as a precursor is carried out under MWI in the presence of urea as a nitrogen source and oleylamine (OAm) as a capping agent for the shape control of the resulting N-doped ZnO nanostructures. Our approach utilizes the MWI process for the decomposition of ZnO2, where the rapid transfer of energy directly to ZnO2 can cause an instantaneous internal temperature rise and, thus, the activation energy for the ZnO2 decomposition is essentially decreased as compared to the decomposition under conductive heating. In the second synthesis method, a one-step synthesis of N-doped ZnO nanostructures is achieved by the rapid decomposition of zinc acetate in a mixture of urea and OAm under MWI. We demonstrate, for the first time, that MWI decomposition of zinc acetate in a mixture of OAm and urea results in the formation of N-doped nanostructures with controlled shape and N-doping level. We report a direct correlation between the intensity of the Raman scattering bands in N-doped ZnO and the concentration of urea used in the synthesis. Electrochemical measurements demonstrate the successful synthesis of stable p-type N-doped ZnO nanostructures using the one-step MWI synthesis and, therefore, allow us to investigate, for the first time, the relationship between the doping level and morphology of the ZnO nanostructures. The results provide strong evidence for the control of the electrical behavior and the nanostructured shapes of ZnO nanoparticles using the facile MWI synthesis method developed in this work.

  4. Robust p-type doping of copper oxide using nitrogen implantation

    Science.gov (United States)

    Jorge, Marina; Polyakov, Stanislav M.; Cooil, Simon; Schenk, Alex K.; Edmonds, Mark; Thomsen, Lars; Mazzola, Federico; Wells, Justin W.

    2017-07-01

    We demonstrate robust p-type doping of Cu2O using low/medium energy ion implantation. Samples are made by controlled oxidation of annealed Cu metal foils, which results in Cu2O with levels of doping close to intrinsic. Samples are then implanted with nitrogen ions using a kinetic energy in the few keV range. Using this method, we are able to produce very high levels of doping, as evidenced by a 350 meV shift in the Fermi level towards the VB maximum. The robustness of the nitrogen implanted samples are tested by exposing them to atmospheric contaminants, and elevated temperatures. The samples are found to survive an increase in temperature of many hundreds of degrees. The robustness of the samples, combined with the fact that the materials used are safe, abundant and non-toxic and that the methods used for the growth of Cu2O and N+ implantation are simple and cheap to implement industrially, underlines the potential of Cu2O:N for affordable intermediate band photovoltaics.

  5. InP nanowire p-type doping via Zinc indiffusion

    Science.gov (United States)

    Haggren, Tuomas; Otnes, Gaute; Mourão, Renato; Dagyte, Vilgaile; Hultin, Olof; Lindelöw, Fredrik; Borgström, Magnus; Samuelson, Lars

    2016-10-01

    We report an alternative pathway for p-type InP nanowire (NW) doping by diffusion of Zn species from the gas phase. The diffusion of Zn was performed in a MOVPE reactor at 350-500 °C for 5-20 min with either H2 environment or additional phosphorus in the atmosphere. In addition, Zn3P2 shells were studied as protective caps during post-diffusion annealing. This post-diffusion annealing was performed to outdiffuse and activate Zn in interstitial locations. The characterization methods included photoluminescence and single NW conductivity and carrier concentration measurements. The acquired carrier concentrations were in the order of >1017 cm-3 for NWs without post-annealing, and up to 1018 cm-3 for NWs annealed with the Zn3P2 shells. The diffused Zn caused redshift to the photoluminescence signal, and the degree of redshift depended on the diffusion process.

  6. High performance p-type NiOx thin-film transistor by Sn doping

    Science.gov (United States)

    Lin, Tengda; Li, Xiuling; Jang, Jin

    2016-06-01

    Major obstacles towards power efficient complementary electronics employing oxide thin-film transistors (TFTs) lie in the lack of equivalent well performing p-channel devices. Here, we report a significant performance enhancement of solution-processed p-type nickel oxide (NiOx) TFTs by introducing Sn dopant. The Sn-doped NiOx (Sn-NiOx) TFTs annealed at 280 °C demonstrate substantially improved electrical performances with the increase in the on/off current ratio (Ion/Ioff) by ˜100 times, field-effect mobility (μlin) by ˜3 times, and the decrease in subthreshold swing by half, comparing with those of pristine NiOx TFTs. X-ray photoelectron spectroscopy and X-ray diffraction results confirm that Sn atoms tend to substitute Ni sites and induce more amorphous phase. A decrease in density of states in the gap of NiOx by Sn doping and the shift of Fermi level (EF) into the midgap lead to the improvements of TFT performances. As a result, Sn-NiOx can be a promising material for the next-generation, oxide-based electronics.

  7. Adjustable hydrazine modulation of single-wall carbon nanotube network field effect transistors from p-type to n-type

    Science.gov (United States)

    Dai, Ruixuan; Xie, Dan; Xu, Jianlong; Sun, Yilin; Sun, MengXing; Zhang, Cheng; Li, Xian

    2016-11-01

    Single-wall carbon nanotube (SWCNT) network field effect transistors (FETs), which show decent p-type electronic properties, have been fabricated. The use of hydrazine as an aqueous solution and a strong n-type dopant for the SWCNTs is demonstrated in this paper. The electrical properties are obviously tuned by hydrazine treatment at different concentrations on the surface of the SWCNT network FETs. The transport behavior of SWCNTs can be modulated from p-type to n-type, demonstrating the controllable and adjustable doping effect of hydrazine. With a higher concentration of hydrazine, more electrons can be transferred from the hydrazine molecules to the SWCNT network films, thus resulting in a change of threshold voltage, carrier mobility and on-current. By cleaning the device, the hydrazine doping effects vanish, which indicates that the doping effects of hydrazine are reversible. Through x-ray photoelectron spectroscopy (XPS) characterization, the doping effects of hydrazine have also been studied.

  8. Realization of Cu-Doped p-Type ZnO Thin Films by Molecular Beam Epitaxy.

    Science.gov (United States)

    Suja, Mohammad; Bashar, Sunayna B; Morshed, Muhammad M; Liu, Jianlin

    2015-04-29

    Cu-doped p-type ZnO films are grown on c-sapphire substrates by plasma-assisted molecular beam epitaxy. Photoluminescence (PL) experiments reveal a shallow acceptor state at 0.15 eV above the valence band edge. Hall effect results indicate that a growth condition window is found for the formation of p-type ZnO thin films, and the best conductivity is achieved with a high hole concentration of 1.54 × 10(18) cm(-3), a low resistivity of 0.6 Ω cm, and a moderate mobility of 6.65 cm(2) V(-1) s(-1) at room temperature. Metal oxide semiconductor capacitor devices have been fabricated on the Cu-doped ZnO films, and the characteristics of capacitance-voltage measurements demonstrate that the Cu-doped ZnO thin films under proper growth conditions are p-type. Seebeck measurements on these Cu-doped ZnO samples lead to positive Seebeck coefficients and further confirm the p-type conductivity. Other measurements such as X-ray diffraction, X-ray photoelectron, Raman, and absorption spectroscopies are also performed to elucidate the structural and optical characteristics of the Cu-doped p-type ZnO films. The p-type conductivity is explained to originate from Cu substitution of Zn with a valency of +1 state. However, all p-type samples are converted to n-type over time, which is mostly due to the carrier compensation from extrinsic defects of ZnO.

  9. Understanding the effect of $n$-type and $p$-type doping in the channel of graphene nanoribbon transistor

    Indian Academy of Sciences (India)

    SUDHANSHU CHOUDHARY; VIKRAM SINGH

    2016-09-01

    In this paper, device performance of graphene nanoribbon field effect transistor (GNRFET) with different doping concentrations in different parts of the channel is reported. The study is performed by using atomistic simulations based on self-consistent solution of Schrodinger’s and Poisson’s equation within the non-equilibrium Green’s function formalism. The transfer and output characteristics suggest that device performance with $n$-type doping in the channel is better with smaller supply voltage compared to higher supply voltage. On increasing the $n$-type doping concentration, we obtained better on-current and output characteristics in comparison with undoped and $p$-type doped channel GNRFET. Further, we introduced step-doping profile in the graphene nanoribbon (GNR) channel and found that the device gives better on-current and good saturation condition when compared to undoped or uniformly-doped channel.

  10. Ferromagnetic ordering of Cr and Fe doped p-type diamond: An ab initio study

    Energy Technology Data Exchange (ETDEWEB)

    Benecha, E. M. [Department of Physics, University of South Africa, P.O Box 392, UNISA 0003, Pretoria (South Africa); Lombardi, E. B. [College of Graduate Studies, University of South Africa, P.O Box 392, UNISA 0003, Pretoria (South Africa)

    2014-02-21

    Ferromagnetic ordering of transition metal dopants in semiconductors holds the prospect of combining the capabilities of semiconductors and magnetic systems in single hybrid devices for spintronic applications. Various semiconductors have so far been considered for spintronic applications, but low Curie temperatures have hindered room temperature applications. We report ab initio DFT calculations on the stability and magnetic properties of Fe and Cr impurities in diamond, and show that their ground state magnetic ordering and stabilization energies depend strongly on the charge state and type of co-doping. We predict that divacancy Cr{sup +2} and substitutional Fe{sup +1} order ferromagnetically in p-type diamond, with magnetic stabilization energies (and magnetic moment per impurity ion) of 16.9 meV (2.5 μ{sub B}) and 33.3 meV (1.0 μ{sub B}), respectively. These magnetic stabilization energies are much larger than what has been achieved in other semiconductors at comparable impurity concentrations, including the archetypal dilute magnetic semiconductor GaAs:Mn. In addition, substitutional Fe{sup +1} exhibits a strong half-metallic character, with the Fermi level crossing bands in only the spin down channel. These results, combined with diamond’s extreme properties, demonstrate that Cr or Fe dopedp-type diamond may successfully be considered in the search for room temperature spintronic materials.

  11. 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.

  12. Sodium and potassium doped P-type ZnO films by sol-gel spin-coating technique

    Science.gov (United States)

    Au, Benedict Wen-Cheun; Chan, Kah-Yoong

    2017-07-01

    Zinc oxide (ZnO) is a promising material in a variety of applications including sensors, transistors and solar cells. Many researchers studied N-type ZnO films and reported enhanced properties. On the other hand, P-type ZnO films were rarely attempted due to the self-compensation effect. Success in achieving P-type ZnO films is important as it will pave the way for more advanced complementary devices. In this work, P-type sodium and potassium doped ZnO films were fabricated on glass substrates with doping concentration between 0 and 25 at.%. The influences of doping concentration on surface morphology, structural, optical and electrical properties were investigated using atomic force microscopy, X-ray diffraction spectroscopy, energy-dispersive X-ray spectroscopy, ultraviolet-visible (UV-Vis) spectrophotometer, photoluminescence spectroscopy and Hall-effect electrical transport measurement system. The distinctive behavior of P-type ZnO films with different doping concentrations will be discussed.

  13. Growth of nitrogen-doped p-type ZnO thin films prepared by atomic layer epitaxy

    Institute of Scientific and Technical Information of China (English)

    LEE Chongmu; LIM Jongmin; PARK Suyoung; KIM Hyounwoo

    2006-01-01

    Nitrogen-doped, p-type ZnO thin films were grown successfully on sapphire (0001) substrates by using atomic layer epitaxy (ALE). Zn(C2H5)2[Diethylzinc,DEZn], H2O and NH3 were used as a zinc precursor, an oxidant and a doping source gas, respectively. The lowest electrical resistivity of the p-type ZnO films grown by ALE and annealed at 1000 ℃ in an oxygen atmosphere for 1 h was 18.3 Ω·m with a hole concentration of 3.71×1017cm-3 . Low temperature-photoluminescence analysis and time-dependent Hall measurement results support that the nitrogen-doped ZnO after annealing is ap-type semiconductor.

  14. 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.

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

    National Research Council Canada - National Science Library

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

    2015-01-01

    .... 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...

  16. 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 (ReS2) with Mo via chemical vapor deposition. Scanning transmission electron microscopy demonstrated that Mo atoms are successfully doped into ReS2 by substitutionally replacing Re atoms in the lattice. Electrical measurements revealed the degenerate p-type semiconductor behavior of Mo-doped ReS2 field effect transistors, in agreement with density functional theory calculations. The p-n diode device based on a doped ReS2 and ReS2 homojunction exhibited gate-tunable current rectification behaviors, and the maximum rectification ratio could reach up to 150 at Vd = -2/+2 V. The successful synthesis of p-type ReS2 in this study could largely promote its application in novel electronic and optoelectronic devices.

  17. Perovskite Sr-doped LaCrO3 as a new p-type transparent conducting oxide

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongliang; Du, Yingge; Papadogianni, Alexandra; Bierwagen, Oliver; Sallis, Shawn; Piper, Louis F. J.; Bowden, Mark E.; Shutthanandan, V.; Sushko, Petr; Chambers, Scott A.

    2015-09-16

    Transparent conducting oxides (TCOs) constitute a unique class of materials which combine the seemingly mutually exclusive properties of electrical conductivity and optical transparency in a single material. TCOs are useful for a wide range of applications including solar cells, displays, light emitting diodes and transparent electronics. Simple post-transition metal oxides such as ZnO, In2O3 and SnO2 are wide gap insulators in which the ionic character generates an oxygen 2p-derived valence band (VB) and a metal s-derived conduction band (CB), resulting in large optical band gaps (>3.0 eV) and excellent n-type conductivity when donor doped. In contrast, the development of efficient p-type TCOs remains a global materials challenge. Converting n-type oxides to p-type analogs by acceptor doping is extremely difficult and these materials display poor conductivity.

  18. The synthesis and characterization of Ag-N dual-doped p-type ZnO: experiment and theory.

    Science.gov (United States)

    Duan, Li; Wang, Pei; Yu, Xiaochen; Han, Xiao; Chen, Yongnan; Zhao, Peng; Li, Donglin; Yao, Ran

    2014-03-07

    Ag-N dual-doped ZnO films have been fabricated by a chemical bath deposition method. The p-type conductivity of the dual-doped ZnO:(Ag, N) is stable over a long period of time, and the hole concentration in the ZnO:(Ag, N) is much higher than that in mono-doped ZnO:Ag or ZnO:N. We found that this is because AgZn-NO complex acceptors can be formed in ZnO:(Ag, N). First-principles calculations show that the complex acceptors generate a fully occupied band above the valance band maximum, so the acceptor levels become shallower and the hole concentration is increased. Furthermore, the binding energy of the Ag-N complex in ZnO is negative, so ZnO:(Ag, N) can be stable. These results indicate that the Ag-N dual-doping may be expected to be a potential route to achieving high-quality p-type ZnO for use in a variety of devices.

  19. 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.

  20. First-principles study of p-type ZnO by S-Na co-doping

    Science.gov (United States)

    Tan, Xingyi; Li, Qiang; Zhu, Yongdan

    2017-08-01

    Using the first-principles method based on the density functional theory, the formation energy, electronic structures of S-Na co-doping in ZnO were calculated. The calculated results show that NaZn-SO have smaller formation energy than Nain-SO in energy ranges from -3.10 to 0 eV of {μ }{{O}}, indicating that it opens up a new opportunity for growth the p-type ZnO. The band structure shows that the NaZn system is a p-type direct-band-gap semiconductor material and the calculated band gap (0.84 eV) is larger than pure ZnO (0.74 eV). The NaZn-SO system is also a p-type semiconductor material with a direct band gap (0.80 eV). The influence of S-Na co-doping in ZnO on p-type conductivity is also discussed. The effective masses of NaZn-SO are larger than effective masses of NaZn and the NaZn-SO have more hole carriers than NaZn, meaning the hole in the NaZn-SO system may have a better carrier transfer character. So we inferred that NaZn-SO should be a candidate of p-type conduction. Project supported by the Natural Science Foundation of Hubei Province, China (Nos. 2014CFB342, 2014CFB619) and the Doctoral Foundation for Scientific Research of Hubei University for Nationalities (No. MY2013B020).

  1. Emitter formation using laser doping technique on n- and p-type c-Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    López, G., E-mail: gema.lopez@upc.edu; Ortega, P.; Colina, M.; Voz, C.; Martín, I.; Morales-Vilches, A.; Orpella, A.; Alcubilla, R.

    2015-05-01

    Highlights: • We use laser doping technique to create highly-doped regions. • Dielectric layers are used as both passivating layer and dopant source. • The high quality of the junctions makes laser doping technique using dielectric layers as dopant source suitable for solar cells applications. - Abstract: In this work laser doping technique is used to create highly-doped regions defined in a point-like structure to form n+/p and p+/n junctions applying a pulsed Nd-YAG 1064 nm laser in the nanosecond regime. In particular, phosphorous-doped silicon carbide stacks (a-SiC{sub x}/a-Si:H (n-type)) deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) and aluminum oxide (Al{sub 2}O{sub 3}) layers deposited by atomic layer deposition (ALD) on 2 ± 0.5 Ω cm p- and n-type FZ c-Si substrates respectively are used as dopant sources. Laser power and number of pulses per spot are explored to obtain the optimal electrical behavior of the formed junctions. To assess the quality of the p+ and n+ regions, the junctions are electrically contacted and characterized by means of dark J–V measurements. Additionally, a diluted HF treatment previous to front metallization has been explored in order to know its impact on the junction quality. The results show that fine tuning of the energy pulse is critical while the number of pulses has minor effect. In general the different HF treatments have no impact in the diode electrical behavior except for an increase of the leakage current in n+/p junctions. The high electrical quality of the junctions makes laser doping, using dielectric layers as dopant source, suitable for solar cell applications. Particularly, a potential open circuit voltage of 0.64 V (1 sun) is expected for a finished solar cell.

  2. An Sb-doped p-type ZnO nanowire based random laser diode.

    Science.gov (United States)

    Bashar, Sunayna B; Suja, Mohammad; Morshed, Muhammad; Gao, Fan; Liu, Jianlin

    2016-02-12

    An electrically pumped Sb-doped ZnO nanowire/Ga-doped ZnO p-n homojunction random laser is demonstrated. Catalyst-free Sb-doped ZnO nanowires were grown on a Ga-doped ZnO thin film on a Si substrate by chemical vapor deposition. The morphology of the as-grown titled nanowires was observed by scanning electron microscopy. X-ray photoelectron spectroscopy results indicated the incorporation of Sb dopants. Shallow acceptor states of Sb-doped nanowires were confirmed by photoluminescence measurements. Current-voltage measurements of ZnO nanowire structures assembled from p- and n-type materials showed a typical p-n diode characteristic with a threshold voltage of about 7.5 V. Very good photoresponse was observed in the UV region operated at 0 V and different reverse biases. Random lasing behavior with a low-threshold current of around 10 mA was demonstrated at room temperature. The output power was 170 nW at 30 mA.

  3. 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.

  4. Sensitive optical bio-sensing of p-type WSe2 hybridized with fluorescent dye attached DNA by doping and de-doping effects

    Science.gov (United States)

    Han, Kyu Hyun; Kim, Jun Young; Jo, Seong Gi; Seo, Changwon; Kim, Jeongyong; Joo, Jinsoo

    2017-10-01

    Layered transition metal dichalcogenides, such as MoS2, WSe2 and WS2, are exciting two-dimensional (2D) materials because they possess tunable optical and electrical properties that depend on the number of layers. In this study, the nanoscale photoluminescence (PL) characteristics of the p-type WSe2 monolayer, and WSe2 layers hybridized with the fluorescent dye Cy3 attached to probe-DNA (Cy3/p-DNA), have been investigated as a function of the concentration of Cy3/DNA by using high-resolution laser confocal microscopy. With increasing concentration of Cy3/p-DNA, the measured PL intensity decreases and its peak is red-shifted, suggesting that the WSe2 layer has been p-type doped with Cy3/p-DNA. Then, the PL intensity of the WSe2/Cy3/p-DNA hybrid system increases and the peak is blue-shifted through hybridization with relatively small amounts of target-DNA (t-DNA) (50–100 nM). This effect originates from charge and energy transfer from the Cy3/DNA to the WSe2. For t-DNA detection, our systems using p-type WSe2 have the merit in terms of the increase of PL intensity. The p-type WSe2 monolayers can be a promising nanoscale 2D material for sensitive optical bio-sensing based on the doping and de-doping responses to biomaterials.

  5. Growth and electrical properties of high-quality Mg-doped P-type A10.2Ga0.8N films

    Institute of Scientific and Technical Information of China (English)

    Zhou Xiaowei; Li Peixian; Xu Shengrui; Hao Yue

    2009-01-01

    The growth of high-performance Mg-doped p-type AlxGa1-xN(X=0.2)using metal-organic chemical vapor deposition is reported.The influence of growth conditions(growth temperature,magnesium flow,and thermal annealing temperature)on the electrical properties of Mg-doped p-type AlxGa1-xN(X=0.2)has been investigated.Using the optimized conditions,we obtained a minimum p-type resistivity of 0.71 Ωcm for p-type AlGaN with 20% Al fraction.

  6. 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.

  7. The fabrication of Na doped p-type Zn1- x Mg x O films by pulsed laser deposition

    Science.gov (United States)

    Zhang, L. Q.; Zhang, Y. Z.; Ye, Z. Z.; Lin, S. S.; Lu, B.; He, H. P.; Chen, L. X.; Lu, J. G.; Jiang, J.; Wu, K. W.; Huang, J. Y.; Zhu, L. P.

    2012-01-01

    P-type Zn1- x Mg x O (0≤ x≤0.25) films are obtained through Na doping, as confirmed by repeated Hall-effect measurements and rectification behavior of p-Zn0.81Mg0.19O:Na/ n-Zn0.8Mg0.2O:Al quasi-homojunctions. The absorption and photoluminescence spectra indicate the band gap shifts to higher energy in linearly proportional to Mg content. Critically, X-ray diffraction (XRD) patterns reveal that the strain induced by Na doping can be counteracted through an appropriate content of Mg alloying. Both XRD data and Hall-effect data imply that the solubility of Na acceptor should be enhanced by alloying with Mg. The X-ray photoelectron spectrum (XPS) result indicates the existence of Na. Microstructure structure of the film is confirmed by high-resolution transmission electron microscope.

  8. Emitter formation using laser doping technique on n- and p-type c-Si substrates

    Science.gov (United States)

    López, G.; Ortega, P.; Colina, M.; Voz, C.; Martín, I.; Morales-Vilches, A.; Orpella, A.; Alcubilla, R.

    2015-05-01

    In this work laser doping technique is used to create highly-doped regions defined in a point-like structure to form n+/p and p+/n junctions applying a pulsed Nd-YAG 1064 nm laser in the nanosecond regime. In particular, phosphorous-doped silicon carbide stacks (a-SiCx/a-Si:H (n-type)) deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) and aluminum oxide (Al2O3) layers deposited by atomic layer deposition (ALD) on 2 ± 0.5 Ω cm p- and n-type FZ c-Si substrates respectively are used as dopant sources. Laser power and number of pulses per spot are explored to obtain the optimal electrical behavior of the formed junctions. To assess the quality of the p+ and n+ regions, the junctions are electrically contacted and characterized by means of dark J-V measurements. Additionally, a diluted HF treatment previous to front metallization has been explored in order to know its impact on the junction quality. The results show that fine tuning of the energy pulse is critical while the number of pulses has minor effect. In general the different HF treatments have no impact in the diode electrical behavior except for an increase of the leakage current in n+/p junctions. The high electrical quality of the junctions makes laser doping, using dielectric layers as dopant source, suitable for solar cell applications. Particularly, a potential open circuit voltage of 0.64 V (1 sun) is expected for a finished solar cell.

  9. P-Type Doping of GaN by Mg+ Implantation

    Institute of Scientific and Technical Information of China (English)

    YAO Shu-De; ZHAO Qiang; ZHOU Sheng-Qiang; YANG Zi-Jian; LU Yi-Hong; SUN Chang-Chun; SUN Chang; ZHANG Guo-Yi; VANTOMME Andre; PIPELEERS Bert

    2003-01-01

    Mg+ and Mg++P+ were introduced into GaN by ion implantation. The structure and crystalline quality of the GaN samples were analysed by Rutherford backscattering and channelling spectrometry before (xmin = 1.6%) and after implantation (Xmin = 4.1%). X-ray diffraction reveals the existence of implantation-induced damage in the case of post-implantation followed by rapid thermal annealing. The resistivity, average factor, carrier concentration and carrier mobility were measured by the Hall effect. The transformation from n-type to p-type for GaN was observed.

  10. Hole subband structure in single and double p-type {delta}-doped diamond quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Vargas, I. [Facultad de Ciencias, Univ. Autonoma del Estado de Morelos, Av. Universidad 1001, C.P. 62209, Cuernavaca (Mexico); Duque, C.A. [Inst. de Fisica, Universidad de Antioquia, AA 1226, Medellin (Colombia); Mora-Ramos, M.E. [Facultad de Ciencias, Univ. Autonoma del Estado de Morelos, Av. Universidad 1001, C.P. 62209, Cuernavaca (Mexico); Inst. de Ciencia de Materiales de Madrid, CSIC, Sor Juana Ines de la Cruz 3, 28049 Madrid (Spain); Velasco, V.R. [Inst. de Ciencia de Materiales de Madrid, CSIC, Sor Juana Ines de la Cruz 3, 28049 Madrid (Spain)

    2007-07-01

    Heavy, light, and split-off hole states in single and double p-{delta}-doped diamond quantum wells are studied with the use of a 6 x 6 k.p model. The effective mass Hamiltonian is solved using a local density Thomas-Fermi-Dirac approximation for the description of the band bending profile. The features of the valence band spectrum are briefly discussed in both cases. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Microhardness of carbon-doped (111) p-type Czochralski silicon

    Science.gov (United States)

    Danyluk, S.; Lim, D. S.; Kalejs, J.

    1985-01-01

    The effect of carbon on (111) p-type Czochralski silicon is examined. The preparation of the silicon and microhardness test procedures are described, and the equation used to determine microhardness from indentations in the silicon wafers is presented. The results indicate that as the carbon concentration in the silicon increases the microhardness increases. The linear increase in microhardness is the result of carbon hindering dislocation motion, and the effect of temperature on silicon deformation and dislocation mobility is explained. The measured microhardness was compared with an analysis which is based on dislocation pinning by carbon; a good correlation was observed. The Labusch model for the effect of pinning sites on dislocation motion is given.

  12. Nanopore formation on low-doped p-type silicon under illumination

    Energy Technology Data Exchange (ETDEWEB)

    Chiboub, N. [UDTS, 02 Bd. Frantz Fanon, B.P. 140, Alger-7 Merveilles, 16200 Algiers (Algeria); Gabouze, N., E-mail: ngabouze@yahoo.fr [UDTS, 02 Bd. Frantz Fanon, B.P. 140, Alger-7 Merveilles, 16200 Algiers (Algeria); Chazalviel, J.-N.; Ozanam, F. [Physique de la Matiere Condensee, Ecole Polytechnique, CNRS, 91128 Palaiseau (France); Moulay, S. [Universite Saad Dahleby, B.P. 270, Route de Soumaa, Blida (Algeria); Manseri, A. [UDTS, 02 Bd. Frantz Fanon, B.P. 140, Alger-7 Merveilles, 16200 Algiers (Algeria)

    2010-04-01

    Porous silicon layers were elaborated by anodization of highly resistive p-type silicon in HF/ethylene glycol solution under front side illumination, as a function of etching time, HF concentration and illumination intensity. The porous layer morphology was investigated by scanning electron microscopy (SEM). The illumination during anodization was provided by a tungsten lamp or lasers of different wavelengths. Under anodization, a microporous layer is formed up to a critical thickness above which macropores appear. Under illumination, the instability limiting the growth of the microporous layer occurs at a critical thickness much larger than in the dark. This critical thickness depends on HF concentration, illumination wavelength and intensity. These non-trivial dependencies are rationalized in a model in which photochemical etching in the electrochemically formed porous layer plays the central role.

  13. Fabrication and photoelectric properties of La-doped p-type ZnO nanofibers and crossed p-n homojunctions by electrospinning.

    Science.gov (United States)

    Zhang, H D; Yu, M; Zhang, J C; Sheng, C H; Yan, X; Han, W P; Liu, Y C; Chen, S; Shen, G Z; Long, Y Z

    2015-06-21

    La-doped p-type ZnO nanofibers were successfully synthesized by electrospinning, followed by calcination. The microstructure and morphology of the La-doped ZnO nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The field effect curve of individual nanofibers confirms that the resulting La-doped ZnO fibers are p-type semiconductors. The doping mechanism is discussed. Furthermore, crossed p-n homojunction nanofibers were also prepared based on electrospun La-doped p-type ZnO and n-type pure ZnO fibers. The current-voltage curve shows the typical rectifying characteristic of a p-n homojunction device. The turn-on voltage appears at about 2.5 V under the forward bias and the reverse current is impassable.

  14. Fabrication and photoelectric properties of La-doped p-type ZnO nanofibers and crossed p-n homojunctions by electrospinning

    Science.gov (United States)

    Zhang, H. D.; Yu, M.; Zhang, J. C.; Sheng, C. H.; Yan, X.; Han, W. P.; Liu, Y. C.; Chen, S.; Shen, G. Z.; Long, Y. Z.

    2015-06-01

    La-doped p-type ZnO nanofibers were successfully synthesized by electrospinning, followed by calcination. The microstructure and morphology of the La-doped ZnO nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The field effect curve of individual nanofibers confirms that the resulting La-doped ZnO fibers are p-type semiconductors. The doping mechanism is discussed. Furthermore, crossed p-n homojunction nanofibers were also prepared based on electrospun La-doped p-type ZnO and n-type pure ZnO fibers. The current-voltage curve shows the typical rectifying characteristic of a p-n homojunction device. The turn-on voltage appears at about 2.5 V under the forward bias and the reverse current is impassable.

  15. P-type ZnO films by phosphorus doping using plasma immersion ion-implantation technique

    Science.gov (United States)

    Nagar, S.; Chakrabarti, S.

    2013-03-01

    ZnO has been a subject of intense research in the optoelectronics community owing to its wide bandgap (3.3eV) and large exciton binding energy (60meV). However, difficulty in doping it p-type posts a hindrance in fabricating ZnO-based devices. In order to make p-type ZnO films, phosphorus implantation, using plasma immersion ion-implantation technique (2kV, 900W, 10μs pulse width) for 30 seconds, was performed on ZnO thin film deposited by RF Magnetron Sputtering (Sample A). The implanted samples were subsequently rapid thermal annealed at 700°C and 1000°C (Samples B and C) in oxygen environment for 30 seconds. Low temperature (8K) photoluminescence spectra reveal dominant donor-bound exciton (D°X) peak at 3.36eV for samples A and B. However, for Sample B the peaks around 3.31eV and 3.22eV corresponding to the free electron-acceptor (FA) and donor to acceptor pair peaks (DAP) are also observed. A dominant peak around 3.35eV, corresponding to acceptor bound exciton (A°X) peak, is detected for Sample C along with the presence of FA and DAP peaks around 3.31eV and 3.22eV. Moreover, the deep level peak around 2.5eV is higher for Sample B which may be due to implantation and acceptor related defects. However, for Sample C, the deep level peaks are very weak compared to the near band edge peaks confirming that these peaks are mainly due to intrinsic defects and not related to acceptors. These results clearly show us a promising way to achieve p-type ZnO films using phosphorus doping.

  16. 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.

  17. 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.

  18. 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.

  19. Thomas-Fermi approximation in two p-type delta-doped quantum wells in GaAs an Si

    Energy Technology Data Exchange (ETDEWEB)

    Gaggero-Sager, L. M. [Universidad Autonoma de Zacatecas, Zacatecas (Mexico); M' Peko, J. C.; Perez Alvarez, R. [Universidad de La Habana, Ciudad Habana (Cuba)

    2001-04-01

    Thomas-Fermi calculations of the hole subband structure in two coupled p-type d-doped GaAs and Si quantum wells are carried out as a function of the impurity concentration and the distance l between them. A simple formula is obtained for the potential as a function of these two magnitudes by both types of systems. The numerical results for a double Be-{delta}-doped GaAs (double B-{delta}-doped Si) quantum well show that the energy levels degenerate for l{>=}300 A(l{>=}200 A) for an impurity concentration of 1 x 10{sup 1}3 cm{sup -2}. [Spanish] Presentamos calculos de la estructura de subbandas de huecos, utilizando la aproximacion de Thomas-Fermi para dos pozos cuanticos d-dopados tipo p en GaAs y Si, como funcion de la concentracion de impurezas y de la distancia l entre ambos para los dos tipos de sistemas. Los resultados numericos muestran que para un pozo doble de B-{delta}-dopado GaAs (pozo doble de B-{delta}-dopado Si) con una concentracion de 1 x 10{sup 1}3 cm{sup -2} los niveles estan degenerados para l{>=}300 A(l{>=}200 A).

  20. Semiconductor systems utilizing materials that form rectifying junctions in both N and P-type doping regions, whether metallurgically or field induced, and methods of use

    Science.gov (United States)

    Welch, James D.

    2000-01-01

    Disclosed are semiconductor systems, such as integrated circuits utilizing Schotky barrier and/or diffused junction technology, which semiconductor systems incorporate material(s) that form rectifying junctions in both metallurgically and/or field induced N and P-type doping regions, and methods of their use. Disclosed are Schottky barrier based inverting and non-inverting gate voltage channel induced semiconductor single devices with operating characteristics similar to multiple device CMOS systems and which can be operated as modulators, N and P-channel MOSFETS and CMOS formed therefrom, and (MOS) gate voltage controlled rectification direction and gate voltage controlled switching devices, and use of such material(s) to block parasitic current flow pathways. Simple demonstrative five mask fabrication procedures for inverting and non-inverting gate voltage channel induced semiconductor single devices with operating characteristics similar to multiple device CMOS systems are also presented.

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

    Directory of Open Access Journals (Sweden)

    Magali Roques

    2015-11-01

    Full Text Available 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.

  2. Pristine and Al-doped hematite printed films as photoanodes of p-type dye-sensitized solar cells

    Science.gov (United States)

    Congiu, Mirko; De Marco, Maria L.; Bonomo, Matteo; Nunes-Neto, Oswaldo; Dini, Danilo; Graeff, Carlos F. O.

    2017-01-01

    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 AlFe2O4 (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 Fe2O3 and Fe2O3/AlFe2O4 as photoanodes of a tandem DSSC.

  3. Characterization and Stability of Na-doped p-type ZnO Thin Films Preparation by Reactive DC Magnetron Sputtering

    Institute of Scientific and Technical Information of China (English)

    JI Zhen-guo; LIU Fang; HE Hai-yan; HAN Wei-zhi

    2009-01-01

    Na-doped p-type ZnO thin films have been realized by DC reactive magnetron sputtering with a set of metal-Zn targets doped with various Na contents and under different substrate temperatures,respectively.Hall effect measurement,field-emission SEM,X-ray diffraction and optical transmission were carried out to investigate the effects of Na content and substrate temperature on the properties of p-type films. Results indicate that all the Na-doped ZnO films are strongly (002) oriented,and have an average transmittance ~85% in the visible region.Na-doped p-type ZnO films with good structural,electrical,and optical properties can only be obtained at an intermediate amount of Na content and under appropriate substrate temperature.At the optimal condition,the Na-doped p-type ZnO has the lowest resistivity of 13.8Ω· cm with the carrier concentration as high as 1.07×10~(18) cm~(-3).The stability of the Na-doped p-type ZnO is also studied in this paper and it is found that the electrical properties keep stable in a period of one month.

  4. Origin of p-type conductivity of Sb-doped ZnO nanorods and the local structure around Sb ions

    Energy Technology Data Exchange (ETDEWEB)

    Liang, J. K.; Su, H. L., E-mail: suhlnju@hotmail.com, E-mail: ycwu@hfut.edu.cn, E-mail: jcahuang@mail.ncku.edu.tw; Wu, Y. C., E-mail: suhlnju@hotmail.com, E-mail: ycwu@hfut.edu.cn, E-mail: jcahuang@mail.ncku.edu.tw [School of Materials Science and Engineering and Anhui Provincial Key Laboratory of Advanced Functional Materials and Devices, Hefei University of Technology, Hefei 230009, Anhui (China); Chuang, P. Y.; Kuo, C. L.; Huang, S. Y. [Department of Physics, National Cheng Kung University, Tainan 701, Taiwan (China); Chan, T. S. [National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan (China); Huang, J. C. A., E-mail: suhlnju@hotmail.com, E-mail: ycwu@hfut.edu.cn, E-mail: jcahuang@mail.ncku.edu.tw [Department of Physics, National Cheng Kung University, Tainan 701, Taiwan (China); Advanced Optoelectronic Technology Center and Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan (China); Taiwan Consortium of Emergent Crystalline Materials, Ministry of Science and Technology, Taipei 106, Taiwan (China)

    2015-05-25

    To probe the origin of p-type conductivity in Sb-doped ZnO, a careful and detailed synchrotron radiation study was performed. The extended X-ray absorption fine structure and X-ray photoelectron spectroscopy investigations provided the evidence for the formation of the complex defects comprising substitution Sb ions at Zn sites (Sb{sub Zn}) and Zn vacancies within the Sb-doped ZnO lattice. Such complex defects result in the increases of Sb-O coordination number and the Sb valence and thereby lead to the p-type conductivity of Sb-doped ZnO. The back-gate field-effect-transistors based on single nanorod of Sb-doped ZnO were constructed, and the stable p-type conduction behavior was confirmed.

  5. 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)

  6. The electrical properties of photodiodes based on nanostructure gallium doped cadmium oxide/p-type silicon junctions

    Science.gov (United States)

    Çavaş, M.; Yakuphanoğlu, F.; Karataş, Ş.

    2017-01-01

    Gallium doped cadmium-oxide (CdO: Ga) thin films were successfully deposited by sol-gel spin coating method on p-type Si substrate. The electrical properties of the photodiode based on nanostructure Ga doped n-CdO/p-Si junctions were investigated. The current-voltage (I-V) characteristics of the structure were investigated under various light intensity and dark. It was observed that generated photocurrent of the Au/n-CdO/p-Si junctions depended on light intensity. The capacitance-voltage and conductance-voltage measurements were carried out for this diode in the frequency range between 100 and 1000 kHz at room temperature by steps of 100 kHz. The capacitance decreased with increasing frequency due to a continuous distribution of the interface states. These results suggested that the Au/n-CdO/p-Si Schottky junctions could be utilized as a photosensor. Furthermore, the voltage and frequency dependence of series resistance were calculated from the C-V and G/ω-V measurements and plotted as functions of voltage and frequency. The distribution profile of R S -V gave a peak in the depletion region at low frequencies and disappeared with increasing frequencies.

  7. Using the hydrothermal method to grow p-type ZnO nanowires on Al-doped ZnO thin film to fabricate a homojunction diode.

    Science.gov (United States)

    Tseng, Yung-Kuan; Hung, Meng-Chun; Su, Shun-Lung; Li, Sheng-Kai

    2014-10-01

    In this study, the hydrothermal method is used to grow phosphorus-doped ZnO nanowires on Si/SiO2 substrates deposited with Al-doped ZnO thin film. This structure forms a homogeneous p-n junction. In this study, we are the pioneers to use ammonium hypophosphite (NH4H2PO2) as a source of phosphorus to prepare the precursor solution. Ammonium hypophosphite of different concentration levels is used to observe its effects on the growth of nanowires. The results show that the precursor solution prepared from ammonium hypophosphite can produce good crystalline ZnO nanowires while there is no linear relationship between the amounts and concentration levels of phosphorus doped into the nanowires. Whether the phosphorus-doped ZnO nanowires have the characteristics of a p-type semiconductor is indirectly verified by measuring whether the p-n junction made up of Al-doped ZnO thin film and phosphorus-doped ZnO nanowires shows rectifying behavior. I-V measurements are made on the specimens. The results show good rectifying behavior, proving that the phosphorus-doped ZnO nanowires and Al-doped AZO films have p-type and n-type semiconductor properties, constituting a good p-n junction. This result also proves that ammonium hypophosphite is a better source of phosphorus in the hydrothermal method to synthesize phosphorus-doped ZnO nanowires.

  8. 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.

  9. Enhancement of the thermoelectric performance of p-type layered oxide Ca3Co4O9+ through heavy doping and metallic nanoinclusions

    DEFF Research Database (Denmark)

    Van Nong, Ngo; Pryds, Nini; Linderoth, Søren

    2011-01-01

    An effective way to improve the thermoelectric performance (ZT) of layered structured oxide materials by carefully choosing heavy ion doping and introducing metallic nanoinclusions is proposed. A p-type oxide material with remarkable highly improved ZT is successfully fabricated using this approach...

  10. Effect of oxygen and ozone on p-type doping of ultra-thin WSe2 and MoSe2 field effect transistors.

    Science.gov (United States)

    Wang, Shunfeng; Zhao, Weijie; Giustiniano, Francesco; Eda, Goki

    2016-02-14

    We report on the p-type doping effect of oxygen and ozone molecules on mono- and few-layer WSe2 and MoSe2 field effect transistors. We show that adsorption of oxygen and ozone under ambient conditions results in subtantial doping and corresponding enhancement in the hole conductivity of the devices. Ozone-induced doping is found to be rapid and efficient, saturating within minutes of exposure whereas oxygen-induced doping occurs over a period of days to reach the equivalent level of doping. Our observations reveal that the water adlayer on the material surface plays a crucial role in solubilizing oxygen and ozone and in forming a redox couple with a large chemical potential.

  11. Influence of chemically p-type doped active organic semiconductor on the film thickness versus performance trend in cyanine/C60 bilayer solar cells

    Science.gov (United States)

    Jenatsch, Sandra; Geiger, Thomas; Heier, Jakob; Kirsch, Christoph; Nüesch, Frank; Paracchino, Adriana; Rentsch, Daniel; Ruhstaller, Beat; C Véron, Anna; Hany, Roland

    2015-01-01

    Simple bilayer organic solar cells rely on very thin coated films that allow for effective light absorption and charge carrier transport away from the heterojunction at the same time. However, thin films are difficult to coat on rough substrates or over large areas, resulting in adverse shorting and low device fabrication yield. Chemical p-type doping of organic semiconductors can reduce Ohmic losses in thicker transport layers through increased conductivity. By using a Co(III) complex as chemical dopant, we studied doped cyanine dye/C60 bilayer solar cell performance for increasing dye film thickness. For films thicker than 50 nm, doping increased the power conversion efficiency by more than 30%. At the same time, the yield of working cells increased to 80%. We addressed the fate of the doped cyanine dye, and found no influence of doping on solar cell long term stability. PMID:27877804

  12. Influence of chemically p-type doped active organic semiconductor on the film thickness versus performance trend in cyanine/C60 bilayer solar cells.

    Science.gov (United States)

    Jenatsch, Sandra; Geiger, Thomas; Heier, Jakob; Kirsch, Christoph; Nüesch, Frank; Paracchino, Adriana; Rentsch, Daniel; Ruhstaller, Beat; C Véron, Anna; Hany, Roland

    2015-06-01

    Simple bilayer organic solar cells rely on very thin coated films that allow for effective light absorption and charge carrier transport away from the heterojunction at the same time. However, thin films are difficult to coat on rough substrates or over large areas, resulting in adverse shorting and low device fabrication yield. Chemical p-type doping of organic semiconductors can reduce Ohmic losses in thicker transport layers through increased conductivity. By using a Co(III) complex as chemical dopant, we studied doped cyanine dye/C60 bilayer solar cell performance for increasing dye film thickness. For films thicker than 50 nm, doping increased the power conversion efficiency by more than 30%. At the same time, the yield of working cells increased to 80%. We addressed the fate of the doped cyanine dye, and found no influence of doping on solar cell long term stability.

  13. Gas doping ratio effects on p-type hydrogenated nanocrystalline silicon thin films grown by hot-wire chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Luo, P.Q. [Solar Energy Institute, Department of Physics, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)], E-mail: robt@sjtu.edu.cn; Zhou, Z.B. [Solar Energy Institute, Department of Physics, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)], E-mail: zbzhou@sjtu.edu.cn; Chan, K.Y. [Thin Film Laboratory, Faculty of Engineering, Multimedia University, Jalan Multimedia, Cyberjaya 63100, Selangor (Malaysia); Tang, D.Y.; Cui, R.Q.; Dou, X.M. [Solar Energy Institute, Department of Physics, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

    2008-12-30

    Hydrogenated nanocrystalline silicon (nc-Si:H) grown by hot-wire chemical vapor deposition (HWCVD) has recently drawn significant attention in the area of thin-film large area optoelectronics due to possibility of high deposition rate. We report on the effects of diborane (B{sub 2}H{sub 6}) doping ratio on the microstructural and optoelectrical properties of the p-type nc-Si:H thin films grown by HWCVD at low substrate temperature of 200 deg. C and with high hydrogen dilution ratio of 98.8%. An attempt has been made to elucidate the boron doping mechanism of the p-type nc-Si:H thin films deposited by HWCVD and the correlation between the B{sub 2}H{sub 6} doping ratio, crystalline volume fraction, optical band gap and dark conductivity.

  14. A Win-Win Effect for Both the Ferromagnetism and the Dopability of p-Type Doping in ZnO:(Cu+N)

    Science.gov (United States)

    Wei, Ling; Zhang, Wei-Feng

    2013-08-01

    We investigate the electronic structures and magnetic properties of ZnO doped with N, Cu, and (Cu+N) by using a first principles method and considering the strong correlation effect. It is interesting to compare these three systems. ZnO:N has weak p-type doping and unstable ferromagnetism, while ZnO:Cu becomes insulating due to the Jahn—Teller effect. Cu and N codoping can not only greatly improve the dopability of p-type doping accompanying the Jahn—Teller fading, but also enhance the ferromagnetism at the same time. The calculation results indicate that there is a win-win effect between N and Cu dopants in the ZnO:(Cu+N) system, which could possibly find applications in spintronics besides optoelectronics.

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    -specific sequence motifs and structural elements that are linked to transport specificity and mechanistic modulation. Here we provide an overview of the Cu+-transporting ATPases (of subclass PIB) and compare them to the well-studied sarco(endo)plasmic reticulum Ca2 +-ATPase (of subclass PIIA). Cu+ ions in the cell...

  16. Enhanced p-type conductivity and band gap narrowing in heavily Al doped NiO thin films deposited by RF magnetron sputtering.

    Science.gov (United States)

    Nandy, S; Maiti, U N; Ghosh, C K; Chattopadhyay, K K

    2009-03-18

    Stoichiometric NiO, a Mott-Hubbard insulator at room temperature, shows p-type electrical conduction due to the introduction of Ni(2+) vacancies (V(Ni)('')) and self-doping of Ni(3+) ions in the presence of excess oxygen. The electrical conductivity of this important material is low and not sufficient for active device fabrication. Al doped NiO thin films were synthesized by radio frequency (RF) magnetron sputtering on glass substrates at a substrate temperature of 250 °C in an oxygen + argon atmosphere in order to enhance the p-type electrical conductivity. X-ray diffraction studies confirmed the correct phase formation and also oriented growth of NiO thin films. Al doping was confirmed by x-ray photoelectron spectroscopic studies. The structural, electrical and optical properties of the films were investigated as a function of Al doping (0-4 wt%) in the target. The room temperature electrical conductivity increased from 0.01-0.32 S cm (-1) for 0-4% Al doping. With increasing Al doping, above the Mott critical carrier density, energy band gap shrinkage was observed. This was explained by the shift of the band edges due to the existence of exchange and correlation energies amongst the electron-electron and hole-hole systems and also by the interaction between the impurity quasi-particle system.

  17. Studies of arsenic incorporation and P-type doping in epitaxial mercury cadmium telluride thin films grown by molecular beam epitaxy

    Science.gov (United States)

    Zandian, Majid

    Doped layer semiconductor structures provide possibilities for novel electronic devices. Growth of Hg1-xCdxTe by molecular beam epitaxy (MBE) allows precise control over the doping profile and position of heterojunctions as well as structural properties of this ternary alloy. Even though n-type doping using indium is well established, little is known about p-type doping in this material system by MBE. Several elements such as Ag, Au, Sb, Bi and P have been previously used, however high diffusion coefficient and amphoteric behavior of these atoms in HgCdTe has restricted their use in heterojunction devices where control over doping profiles and concentrations is needed. We investigated arsenic incorporation efficiency as a function of As 4 flux and growth temperature. The sticking coefficient of As is substantially higher at lower growth temperature compared to growth at 190°C. For samples grown at 170°C, the etch pit density (EPD) is higher compared to p-type As doped samples grown at 190°C. Higher EPD is associated with columnar twin defects observed in transmission electron microscopy (TEM) studies of low growth temperature samples. Growth at low temperature of 170°C causes Hg rich condition promoting twin formation. Therefore, growth of p-type layers doped with As at low temperatures require optimization of II/VI flux ratio to eliminate columnar twin defects. It is possible to incorporate As at normal MBE growth temperature of 190°C but very high flux of As has to used to overcome low sticking coefficient of As at these temperatures. We proposed a mechanism for the activation of As involving Hg vacancies (VHg··) where Te is moved to a Hg vacancy, leaving behind a Te vacancy, which is then filled by an As atom. The Te that is now on a Hg site (i.e., Te antisite) migrates to the surface and leaves the crystal.

  18. Hot-wire chemical vapor deposition prepared aluminum doped p-type microcrystalline silicon carbide window layers for thin film silicon solar cells

    Science.gov (United States)

    Chen, Tao; Köhler, Florian; Heidt, Anna; Carius, Reinhard; Finger, Friedhelm

    2014-01-01

    Al-doped p-type microcrystalline silicon carbide (µc-SiC:H) thin films were deposited by hot-wire chemical vapor deposition at substrate temperatures below 400 °C. Monomethylsilane (MMS) highly diluted in hydrogen was used as the SiC source in favor of SiC deposition in a stoichiometric form. Aluminum (Al) introduced from trimethylaluminum (TMAl) was used as the p-type dopant. The material property of Al-doped p-type µc-SiC:H thin films deposited with different deposition pressure and filament temperature was investigated in this work. Such µc-SiC:H material is of mainly cubic (3C) SiC polytype. For certain conditions, like high deposition pressure and high filament temperature, additional hexagonal phase and/or stacking faults can be observed. P-type µc-SiC:H thin films with optical band gap E04 ranging from 2.0 to 2.8 eV and dark conductivity ranging from 10-5 to 0.1 S/cm can be prepared. Such transparent and conductive p-type µc-SiC:H thin films were applied in thin film silicon solar cells as the window layer, resulting in an improved quantum efficiency at wavelengths below 480 nm.

  19. Fe-Doping Effect on Thermoelectric Properties of p-Type Bi0.48Sb1.52Te3

    Directory of Open Access Journals (Sweden)

    Hyeona Mun

    2015-03-01

    Full Text Available The substitutional doping approach has been shown to be an effective strategy to improve ZT of Bi2Te3-based thermoelectric raw materials. We herein report the Fe-doping effects on electronic and thermal transport properties of polycrystalline bulks of p-type Bi0.48Sb1.52Te3. After a small amount of Fe-doping on Bi/Sb-sites, the power factor could be enhanced due to the optimization of carrier concentration. Additionally, lattice thermal conductivity was reduced by the intensified point-defect phonon scattering originating from the mass difference between the host atoms (Bi/Sb and dopants (Fe. An enhanced ZT of 1.09 at 300 K was obtained in 1.0 at% Fe-doped Bi0.48Sb1.52Te3 by these synergetic effects.

  20. The low resistive and transparent Al-doped SnO{sub 2} films: p-type conductivity, nanostructures and photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Benouis, C.E. [Department of Material Technology, Physics Faculty, USTOMB University, BP1505 Oran (Algeria); Benhaliliba, M., E-mail: mbenhaliliba@gmail.com [Department of Material Technology, Physics Faculty, USTOMB University, BP1505 Oran (Algeria); Mouffak, Z. [Department of Electrical and Computer Engineering California State University, Fresno, CA (United States); Avila-Garcia, A. [Cinvestav-IPN, Dept. Ingeniería Eléctrica-SEES, Apdo. Postal 14-740, 07000 México, D.F. (Mexico); Tiburcio-Silver, A. [ITT-DIE, Apdo, Postal 20, Metepec 3, 52176 Estado de Mexico (Mexico); Ortega Lopez, M.; Romano Trujillo, R. [Centro de Investigación en Dispositivos Semiconductores, Instituto de Ciencias-BUAP, 14 Sur y Av. San Claudio, C.U. Puebla, Pue. (Mexico); Ocak, Y.S. [Dicle University, Education Faculty, Science Department, 21280 Diyarbakir (Turkey)

    2014-08-01

    Highlights: • Low resistive and high transparency Al doped SnO{sub 2} films. • Films are deposited onto ITO substrate by spray pyrolysis. • Nanostructured films are revealed. • p-Type conductivity is exhibited. • Photoluminescence of films is studied. - Abstract: In this work, we study the crystalline structure, surface morphology, transmittance, optical bandgap and n/p type inversion of tin oxide (SnO{sub 2}). The Nanostructured films of Al-doped SnO{sub 2} were successfully produced onto ITO-coated glass substrates via the spray pyrolysis method at a deposition temperature of 300 °C. A (1 0 1) and (2 1 1)-oriented tetragonal crystal structure was confirmed by X-ray patterns; and grain sizes varied within the range 8−42 nm. The films were polycrystalline, showing a high transparency in the visible (VIS) and infrared (IR) spectra. The optical bandgap was estimated to be around 3.4 eV. The atomic force microscopy (AFM) analysis showed the nanostructures consisting of nanotips, nanopatches, nanopits and nanobubbles. The samples exhibited high conductivity that ranged from 0.55 to 10{sup 4} (S/cm) at ambient and showed an inversion from n to p-type as well as a degenerate semiconductor characters with a bulk concentration reaching 1.7 x 10{sup 19} cm{sup −3}. The photoluminescence measurements reveal the detection of violet, green and yellow emissions.

  1. Reactive ion etching (RIE) induced p- to n-type conversion in extrinsically doped p-type HgCdTe

    Energy Technology Data Exchange (ETDEWEB)

    Musca, C.A.; Smith, E.P.G.; Siliquini, J.F.; Dell, J.M.; Antoszewski, J.; Faraone, L. [Univ. of Western Australia, Nedlands, Western Australia (Australia). Dept. of Electrical and Electronic Engineering; Piotrowski, J. [Vigo System Ltd., Warsaw (Poland)

    1998-12-31

    Mercury annealing of reactive ion etching (RIE) induced p- to n-type conversion in extrinsically doped p-type epitaxial layers of HgCdTe (x = 0.31) has been used to reconvert n-type conversion sustained during RIE processing. For the RIE processing conditions used (400 mT, CH{sub 4}/H{sub 2}, 90 W) p- to n-type conversion was observed using laser beam induced current (LBIC) measurements. After a sealed tube mercury anneal at 200 C for 17 hours, LBIC measurements clearly indicated no n-type converted region remained. Subsequent Hall measurements confirmed that the material consisted of a p-type layer, with electrical properties equivalent to that of the initial as-grown wafer (N{sub A}-N{sub D} = 2 {times} 10{sup 16} cm{sup {minus}3}, {mu} = 350 cm{sup 2}.V{sup {minus}1}.s{sup {minus}1}).

  2. 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.

  3. Iron-boron pairing kinetics in illuminated p-type and in boron/phosphorus co-doped n-type silicon

    Energy Technology Data Exchange (ETDEWEB)

    Möller, Christian, E-mail: cmoeller@cismst.de [CiS Forschungsinstitut für Mikrosensorik und Photovoltaik GmbH, Konrad-Zuse-Str. 14, 99099 Erfurt (Germany); TU Ilmenau, Institut für Physik, Weimarer Str. 32, 98693 Ilmenau (Germany); Bartel, Til; Gibaja, Fabien [Calisolar GmbH, Magnusstraße 11, 12489 Berlin (Germany); Lauer, Kevin [CiS Forschungsinstitut für Mikrosensorik und Photovoltaik GmbH, Konrad-Zuse-Str. 14, 99099 Erfurt (Germany)

    2014-07-14

    Iron-boron (FeB) pairing is observed in the n-type region of a boron and phosphorus co-doped silicon sample which is unexpected from the FeB pair model of Kimerling and Benton. To explain the experimental data, the existing FeB pair model is extended by taking into account the electronic capture and emission rates at the interstitial iron (Fe{sub i}) trap level as a function of the charge carrier densities. According to this model, the charge state of the Fe{sub i} may be charged in n-type making FeB association possible. Further, FeB pair formation during illumination in p-type silicon is investigated. This permits the determination of the charge carrier density dependent FeB dissociation rate and in consequence allows to determine the acceptor concentration in the co-doped n-type silicon by lifetime measurement.

  4. 氧化锌材料p型掺杂研究进展%Recent Research on p-type Doping of ZnO

    Institute of Scientific and Technical Information of China (English)

    谭蜜; 张红; 李万俊; 秦国平; 阮海波; 孔春阳

    2016-01-01

    氧化锌(ZnO)是 II-VI 族直接带隙化合物半导体材料,室温下禁带宽度为3.37 eV,激子束缚能高达60 meV,是制造蓝紫外发光、探测以及激光器件的理想材料。高质量 n 型和 p 型 ZnO 以及同质 p-n 结的制备是实现器件化的关键。目前,n 型 ZnO 的制备技术已趋于成熟,但高质量稳定的 p 型 ZnO 的缺乏已成为制约其器件化的瓶颈。在过去的十余年里,通过国内外科研工作者的不懈努力,在理论和实验上都取得了显著的成果。本文主要概述了 ZnO 材料的 p 型掺杂、p 型导电机制以及 p-ZnO 基光电器件的研究进展,同时初步探索了 ZnO 材料 p 型导电稳定性问题。%Zinc oxide (ZnO),a typical direct wide bandgap (3.37 eV)semiconductor,has attracted an increasing interest tothe optoelectronics field.Its large exciton binding energy of 60 meV endows it with high radiative recom-bination efficiency,a unique advantage in light emitting and lasing devices.The fabrications of high quality n-and p-type ZnO as well as p-n junction are the key steps to realize these applications.although the techniques of fabri-cated n-type ZnO has been well developed,the reliable p type doping of the material remains a major challenge to optoelectronic applications,despitethe fact that p-doping of ZnO has been improved and that marked results in ex-periment and theory have been achieved during the past ten years.In this review,we examined the recent research progress in p-type doping of ZnO,including the p-type performance,the mechanism of p-type conduction,and p-ZnO based photoelectric devices,and so on.Moreover,based on the challenges of the current researches,we sum-marized the factors that may affect the p-type doping,especially the stability of p-type ZnO materials.

  5. Atomic Layer Deposition of p-Type Epitaxial Thin Films of Undoped and N-Doped Anatase TiO2.

    Science.gov (United States)

    Vasu, K; Sreedhara, M B; Ghatak, J; Rao, C N R

    2016-03-01

    Employing atomic layer deposition, we have grown p-type epitaxial undoped and N-doped anatase TiO2(001) thin films on c-axis Al2O3 substrate. From X-ray diffraction and transmission electron microscopy studies, crystallographic relationships between the film and the substrate are found to be (001)TiO2//(0001)Al2O3 and [1̅10]TiO2//[011̅0]Al2O3. N-doping in TiO2 thin films enhances the hole concentration and mobility. The optical band gap of anatase TiO2 (3.23 eV) decreases to 3.07 eV upon N-doping. The epitaxial films exhibit room-temperature ferromagnetism and photoresponse. A TiO2-based homojunction diode was fabricated with rectification from the p-n junction formed between N-doped p-TiO2 and n-TiO2.

  6. Calibration on wide-ranging aluminum doping concentrations by photoluminescence in high-quality uncompensated p-type 4H-SiC

    Science.gov (United States)

    Asada, Satoshi; Kimoto, Tsunenobu; Ivanov, Ivan G.

    2017-08-01

    Previous work has shown that the concentration of shallow dopants in a semiconductor can be estimated from the photoluminescence (PL) spectrum by comparing the intensity of the bound-to-the-dopant exciton emission to that of the free exciton. In this work, we study the low-temperature PL of high-quality uncompensated Al-doped p-type 4H-SiC and propose algorithms for determining the Al-doping concentration using the ratio of the Al-bound to free-exciton emission. We use three different cryogenic temperatures (2, 41, and 79 K) in order to cover the Al-doping range from mid 1014 cm-3 up to 1018 cm-3. The Al-bound exciton no-phonon lines and the strongest free-exciton replica are used as a measure of the bound- and free-exciton emissions at a given temperature, and clear linear relationships are obtained between their ratio and the Al-concentration at 2, 41, and 79 K. Since nitrogen is a common unintentional donor dopant in SiC, we also discuss the criteria allowing one to determine from the PL spectra whether a sample can be considered as uncompensated or not. Thus, the low-temperature PL provides a convenient non-destructive tool for the evaluation of the Al concentration in 4H-SiC, which probes the concentration locally and, therefore, can also be used for mapping the doping homogeneity.

  7. Spectroscopic characterization of a single dangling bond on a bare Si(100)- c ( 4 × 2 ) surface for n - and p -type doping

    KAUST Repository

    Mantega, M.

    2012-07-19

    We investigate the charging state of an isolated single dangling bond formed on an unpassivated Si(100) surface with c(4×2) reconstruction, by comparing scanning tunneling microscopy and spectroscopy analysis with density functional theory calculations. The dangling bond is created by placing a single hydrogen atom on the bare surface with the tip of a scanning tunneling microscope. The H atom passivates one of the dimer dangling bonds responsible for the surface one-dimensional electronic structure. This leaves a second dangling at the reacted surface dimer which breaks the surface periodicity. We consider two possible H adsorption configurations for both the neutral and the doped situation (n- and p-type). In the case of n-doping we find that the single dangling bond state is doubly occupied and the most stable configuration is that with H bonded to the bottom Si atom of the surface dimer. In the case of p-doping the dangling bond is instead empty and the configuration with the H attached to the top atom of the dimer is the most stable. Importantly the two configurations have different scattering properties and phase shift fingerprints. This might open up interesting perspectives for fabricating a switching device by tuning the doping level or by locally charging the single dangling bond state. © 2012 American Physical Society.

  8. Water- and humidity-enhanced UV detector by using p-type La-doped ZnO nanowires on flexible polyimide substrate.

    Science.gov (United States)

    Hsu, Cheng-Liang; Li, Hsieh-Heng; Hsueh, Ting-Jen

    2013-11-13

    High-density La-doped ZnO nanowires (NWs) were grown hydrothermally on flexible polyimide substrate. The length and diameter of the NWs were around 860 nm and 80-160 nm, respectively. All XRD peaks of the La-doped sample shift to a larger angle. The strong PL peak of the La-doped sample is 380 nm, which is close to the 3.3 eV ZnO bandgap. That PL dominated indicates that the La-doped sample has a great amount of oxygen vacancies. The lattice constants ~0.514 nm of the ZnO:La NW were smaller when measured by HR-TEM. The EDX spectrum determined that the La-doped sample contains approximately 1.27 at % La. The La-doped sample was found to be p-type by Hall Effect measurement. The dark current of the p-ZnO:La NWs decreased with increased relative humidity (RH), while the photocurrent of the p-ZnO:La nanowires increased with increased RH. The higher RH environment was improved that UV response performance. Based on the highest 98% RH, the photocurrent/dark current ratio was around 47.73. The UV response of water drops on the p-ZnO:La NWs was around 2 orders compared to 40% RH. In a water environment, the photocurrent/dark current ratio of p-ZnO:La NWs was 212.1, which is the maximum UV response.

  9. Rhodium-doped barium titanate perovskite as a stable p-type semiconductor photocatalyst for hydrogen evolution under visible light.

    Science.gov (United States)

    Maeda, Kazuhiko

    2014-02-12

    Rhodium-doped barium titanate (BaTiO3:Rh) powder was prepared by the polymerized complex (PC) method, and the photocatalytic activity for H2 evolution from water was examined. BaTiO3 is a wide-gap n-type semiconductor having a band gap of 3.0 eV. Doping Rh species into the lattice of BaTiO3 resulted in the formation of new absorption bands in visible light region. Upon visible light (λ > 420 nm), BaTiO3:Rh modified with nanoparticulate Pt as a water reduction promoter was capable of producing H2 from water containing an electron donor such as methanol and iodide. The best material prepared by the PC method exhibited higher activity than that made by a conventional solid-state reaction method. Visible-light-driven Z-scheme water splitting was also accomplished using Pt/BaTiO3:Rh as a building block for H2 evolution in combination with PtOx-loaded WO3 as an O2 evolution photocatalyst in the presence of an IO3(-)/I(-) shuttle redox mediator. Photoelectrochemical analysis indicated that a porous BaTiO3:Rh electrode exhibited cathodic photoresponse due to water reduction in a neutral aqueous Na2SO4 solution upon visible light.

  10. Improvement in the Photocurrent of Inverted Organic Solar Cells Using MoO(x)-Doped TAPC as a P-Type Optical Spacer.

    Science.gov (United States)

    Song, Jiyun; Song, Hyung-Jun; Kim, Jun Young; Lee, Yeonkyung; Park, Myeongjin; Kwon, Yongwon; Ko, Youngjun; Lee, Changhee

    2016-05-01

    In this work, we demonstrate enhancement in the short-circuit current of inverted organic photovoltaic cells (OPVs) using a p-type optical spacer. The p-type optical spacer, which consists of molybdenum oxide (MoO(x))-doped 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), shows improved transmittance at visible light with high electrical conductivity. The electrical field distribution of incident light at the active layer of OPVs can be controlled by tuning the thickness of the optical spacer in the OPVs. Specifically, the incorporation of the 20-nm optical spacer layer in the OPV leads to enhanced spectral response of the device in the wavelength range of 400-600 nm, which is consistent with the combined results of improved optical absorption and better charge transport characteristics. As a result, the OPV with a 20-nm p-type optical spacer shows improvement in the short-circuit current compared with a device with 10 nm of embedded MoO(x).

  11. Effect of Substitutional Pb Doping on Bipolar and Lattice Thermal Conductivity in p-Type Bi0.48Sb1.52Te3

    Directory of Open Access Journals (Sweden)

    Hyun-sik Kim

    2017-07-01

    Full Text Available Cation substitutional doping is an effective approach to modifying the electronic and thermal transports in Bi2Te3-based thermoelectric alloys. Here we present a comprehensive analysis of the electrical and thermal conductivities of polycrystalline Pb-doped p-type bulk Bi0.48Sb1.52Te3. Pb doping significantly increased the electrical conductivity up to ~2700 S/cm at x = 0.02 in Bi0.48-xPbxSb1.52Te3 due to the increase in hole carrier concentration. Even though the total thermal conductivity increased as Pb was added, due to the increased hole carrier concentration, the thermal conductivity was reduced by 14–22% if the contribution of the increased hole carrier concentration was excluded. To further understand the origin of reduction in the thermal conductivity, we first estimated the contribution of bipolar conduction to thermal conductivity from a two-parabolic band model, which is an extension of the single parabolic band model. Thereafter, the contribution of additional point defect scattering caused by Pb substitution (Pb in the cation site was analyzed using the Debye–Callaway model. We found that Pb doping significantly suppressed both the bipolar thermal conduction and lattice thermal conductivity simultaneously, while the bipolar contribution to the total thermal conductivity reduction increased at high temperatures. At Pb doping of x = 0.02, the bipolar thermal conductivity decreased by ~30% from 0.47 W/mK to 0.33 W/mK at 480 K, which accounts for 70% of the total reduction.

  12. Contrasting the Role of Mg and Ba Doping on the Microstructure and Thermoelectric Properties of p-Type AgSbSe2.

    Science.gov (United States)

    Liu, Zihang; Shuai, Jing; Geng, Huiyuan; Mao, Jun; Feng, Yan; Zhao, Xu; Meng, Xianfu; He, Ran; Cai, Wei; Sui, Jiehe

    2015-10-21

    Microstructure has a critical influence on the mechanical and functional properties. For thermoelectric materials, deep understanding of the relationship of microstructure and thermoelectric properties will enable the rational optimization of the ZT value and efficiency. Herein, taking AgSbSe2 as an example, we first report a different role of alkaline-earth metal ions (Mg(2+) and Ba(2+)) doping in the microstructure and thermoelectric properties of p-type AgSbSe2. For Mg doping, it monotonously increases the carrier concentration and then reduces the electrical resistivity, leading to a substantially enhanced power factor in comparison to those of other dopant elements (Bi(3+), Pb(2+), Zn(2+), Na(+), and Cd(2+)) in the AgSbSe2 system. Meanwhile, the lattice thermal conductivity is gradually suppressed by point defects scattering. In contrast, the electrical resistivity first decreases and then slightly rises with the increased Ba-doping concentrations due to the presence of BaSe3 nanoprecipitates, exhibiting a different variation tendency compared with the corresponding Mg-doped samples. More significantly, the total thermal conductivity is obviously reduced with the increased Ba-doping concentrations partially because of the strong scattering of medium and long wavelength phonons via the nanoprecipitates, consistent with the theoretical calculation and analysis. Collectively, ZT value ∼1 at 673 K and calculated leg efficiency ∼8.5% with Tc = 300 K and Th = 673 K are obtained for both AgSb0.98Mg0.02Se2 and AgSb0.98Ba0.02Se2 samples.

  13. Promoting oxygen vacancy formation and p-type conductivity in SrTiO3via alkali metal doping: a first principles study.

    Science.gov (United States)

    Triggiani, Leonardo; Muñoz-García, Ana B; Agostiano, Angela; Pavone, Michele

    2016-10-19

    Strontium titanate (SrTiO3, STO) is a prototypical perovskite oxide, widely exploited in many technological applications, from catalysis to energy conversion devices. In the context of solid-oxide fuel cells, STO has been recently applied as an epitaxial substrate for nano-sized layers of mixed ion-electron conductive catalysts with enhanced electrochemical performances. To extend the applications of such heterogeneous nano-cathodes in real devices, also the STO support should be active for both electron transport and oxide diffusion. To this end, we explored using first-principles calculations the strategy of doping of STO at the Sr site with sodium and potassium. These two ions fit in the perovskite structure and induce holes in the STO valence band, so as to obtain the desired p-type electronic conduction. At the same time, the doping with alkali ions also promotes the formation of oxygen vacancies in STO, a prerequisite for effective oxide diffusion. Analysis of electron density rearrangements upon defect formation allows relating the favorable vacancy formation energies to an improved electronic delocalization over the oxide sub-lattice, as observed in closely related materials (e.g. Sr2Fe1.5Mo0.5O6). Overall, our results suggest the alkali-doped STO as a new potential substrate material in nanoscale heterogeneous electrodes for solid oxide electrochemical cells.

  14. The effect of electronic orbital interactions on p-type doping tendency in ZnO series: First-principles calculations

    Institute of Scientific and Technical Information of China (English)

    Zhang Fang-Ying; You Jian-Qiang; Zeng Zhi; Zhong Guo-Hua

    2007-01-01

    The electronic structures and optical properties of B3 ZnO series of Zn4X4-yMy(X =O, S, Se or Te; M = N,Sb, Cl or I; y = 0 or 1) are studied by first-principles calculations using a pseudopotential plane-wave method. The results show that Zn d-X p orbital interactions play an important role in the p-type doping tendency in zinc-based Ⅱ-Ⅵ semiconductors. In ZnX, with increasing atomic number of X, Zn d-X p orbital interactions decrease and Zn s-X p orbital interactions increase. Additionally, substituting group-Ⅴ elements for X will reduce the Zn d-X p orbital interactions while substituting group-Ⅶ elements for X will increase the Zn d-X p orbital interactions. The results also show that group-Ⅴ-doped ZnX and group-Ⅶ-doped ZnX exhibit different optical behaviours due to their different orbital interaction effects.

  15. Electron mobility in modulation-doped heterostructures

    Science.gov (United States)

    Walukiewicz, W.; Ruda, H. E.; Lagowski, J.; Gatos, H. C.

    1984-01-01

    A model for electron mobility in a two-dimensional electron gas confined in a triangular well was developed. All major scattering processes (deformation potential and piezoelectric acoustic, polar optical, ionized impurity, and alloy disorder) were included, as well as intrasubband and intersubband scattering. The model is applied to two types of modulation-doped heterostructures, namely GaAs-GaAlAs and In(0.53)Ga(0.47)As-Al(0.52)In(0.48)As. In the former case, phonons and remote ionized impurities ultimately limit the mobility, whereas in the latter, alloy disorder is a predominant scattering process at low temperatures. The calculated mobilities are in very good agreement with recently reported experimental characteristics for both GaAs-Ga(1-x)Al(x)As and In(0.53)Ga(0.47)As-Al(0.52)In(0.48)As modulation-doped heterostructures.

  16. Systematic Study of p-type Doping and Related Defects in III-Nitrides: Pathway toward a Nitride HBT

    Science.gov (United States)

    2012-11-20

    indium and gallium and were between 0.24 and 0.3 × 10-7 Torr normalized BEP . InGaN was grown via MME using a shutter modulation scheme similar to...surface for subsequent growth.18, 20-23 The aluminum flux during the buffer layer growth was 6x10-7 Torr beam equivalent pressure ( BEP ), and the...Gallium was supplied by either a standard effusion cell or a Veeco SUMO® cell at a metal-rich flux of 6.5x10-7 to 7.5x10-7 Torr BEP . Gallium and

  17. Direct identification of interstitial Mn in heavily p-type doped GaAs and evidence of its high thermal stability

    CERN Document Server

    Pereira, LMC; Correia, JG; Decoster, S; da Silva, MR; Araújo, JP; Vantomme, A

    2011-01-01

    We report on the lattice location of Mn in heavily p-type doped GaAs by means of $\\beta^{-}$-emission channeling from the decay of $^{56}$Mn. The majority of the Mn atoms substitute for Ga and up to 31% occupy the tetrahedral interstitial site with As nearest neighbors. Contrary to the general belief, we find that interstitial Mn is immobile up to 400$^{\\circ}$C, with an activation energy for diffusion of 1.7–2.3 eV. Such high thermal stability of interstitial Mn has significant implications on the strategies and prospects for achieving room temperature ferromagnetism in Ga$_{1−x}$Mn$_{x}$As.

  18. Low temperature p-type doping of (Al)GaN layers using ammonia molecular beam epitaxy for InGaN laser diodes

    Energy Technology Data Exchange (ETDEWEB)

    Malinverni, M., E-mail: marco.malinverni@epfl.ch; Lamy, J.-M.; Martin, D.; Grandjean, N. [ICMP, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Feltin, E.; Dorsaz, J. [NOVAGAN AG, CH-1015 Lausanne (Switzerland); Castiglia, A.; Rossetti, M.; Duelk, M.; Vélez, C. [EXALOS AG, CH-8952 Schlieren (Switzerland)

    2014-12-15

    We demonstrate state-of-the-art p-type (Al)GaN layers deposited at low temperature (740 °C) by ammonia molecular beam epitaxy (NH{sub 3}-MBE) to be used as top cladding of laser diodes (LDs) with the aim of further reducing the thermal budget on the InGaN quantum well active region. Typical p-type GaN resistivities and contact resistances are 0.4 Ω cm and 5 × 10{sup −4} Ω cm{sup 2}, respectively. As a test bed, we fabricated a hybrid laser structure emitting at 400 nm combining n-type AlGaN cladding and InGaN active region grown by metal-organic vapor phase epitaxy, with the p-doped waveguide and cladding layers grown by NH{sub 3}-MBE. Single-mode ridge-waveguide LD exhibits a threshold voltage as low as 4.3 V for an 800 × 2 μm{sup 2} ridge dimension and a threshold current density of ∼5 kA cm{sup −2} in continuous wave operation. The series resistance of the device is 6 Ω and the resistivity is 1.5 Ω cm, confirming thereby the excellent electrical properties of p-type Al{sub 0.06}Ga{sub 0.94}N:Mg despite the low growth temperature.

  19. Low-Temperature Facile Synthesis of Sb-Doped p-Type ZnO Nanodisks and Its Application in Homojunction Light-Emitting Diode.

    Science.gov (United States)

    Baek, Sung-Doo; Biswas, Pranab; Kim, Jong-Woo; Kim, Yun Cheol; Lee, Tae Il; Myoung, Jae-Min

    2016-05-25

    This study explores low-temperature solution-process-based seed-layer-free ZnO p-n homojunction light-emitting diode (LED). In order to obtain p-type ZnO nanodisks (NDs), antimony (Sb) was doped into ZnO by using a facile chemical route at 120 °C. The X-ray photoelectron spectra indicated the presence of (SbZn-2VZn) acceptor complex in the Sb-doped ZnO NDs. Using these NDs as freestanding templates, undoped n-type ZnO nanorods (NRs) were epitaxially grown at 95 °C to form ZnO p-n homojunction. The homojunction with a turn-on voltage of 2.5 V was found to be significantly stable up to 100 s under a constant voltage stress of 5 V. A strong orange-red emission was observed by the naked eye under a forward bias of 5 V. The electroluminescence spectra revealed three major peaks at 400, 612, and 742 nm which were attributed to the transitions from Zni to VBM, from Zni to Oi, and from VO to VBM, respectively. The presence of these deep-level defects was confirmed by the photoluminescence of ZnO NRs. This study paves the way for future applications of ZnO homojunction LEDs using low-temperature and low-cost solution processes with the controlled use of native defects.

  20. N and Al co-doping as a way to p-type ZnO without post-growth annealing

    Science.gov (United States)

    Snigurenko, Dymitr; Guziewicz, Elzbieta; Krajewski, Tomasz A.; Jakiela, Rafal; Syryanyy, Yevgen; Kopalko, Krzysztof; Paszkowicz, Wojciech

    2016-12-01

    We demonstrate experimental results on p-type ZnO films grown by atomic layer deposition (ALD) and co-doped with aluminum and nitrogen (ANZO). The films were obtained at low temperature (100 °C) with different N to Al ratio and show conductivity type, which depends on the N and Al content. We applied the x-ray photoelectron spectroscopy in order to get insight into a chemical nature of dopants and we found three pronounced contributions of the N1s core level which appear at binding energies of 396.1, 397.4 and around 399 eV. Based on ANZO and undoped ZnO films, both grown by the ALD technique, the ZnO homojunction was obtained in one technological process without any post-growth high temperature processing. The rectification ratio as high as 4 × 104 at ± 2 V was achieved when an ultrathin Al2O3 layer was inserted between p- and n-type ZnO and a n-type ZnO buffer layer deposited on an insulating Si substrate was applied.

  1. 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.

  2. 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.

  3. Correspondence between MOS and modulation-doped structures

    Science.gov (United States)

    Pierret, R. F.; Lundstrom, M. S.

    1984-03-01

    There is currently considerable interest in the development of modulation-doped field-effect transistors suitable for high-speed applications. A promising version of the modulation-doped FET consists of a Schottky-barrier contact atop a thin Al(x)Ga(1-x)As layer on a lightly doped GaAs underlayer. It is pointed out that for a n-AlGaAs/p-GaAs structure, the conduction band discontinuity at the AlGaAs-GaAs interface gives rise to an inversion layer at the GaAs surface. The present paper is concerned with the physical correspondence between n-AlGaAs/p-GaAs modulation-doped structures and MOS structures. It is shown that certain key modulation-doped relationships can be obtained directly from MOSFET relationships.

  4. Cross-section imaging and p-type doping assessment of ZnO/ZnO:Sb core-shell nanowires by scanning capacitance microscopy and scanning spreading resistance microscopy

    Science.gov (United States)

    Wang, Lin; Sallet, Vincent; Sartel, Corinne; Brémond, Georges

    2016-08-01

    ZnO/ZnO:Sb core-shell structured nanowires (NWs) were grown by the metal organic chemical vapor deposition method where the shell was doped with antimony (Sb) in an attempt to achieve ZnO p-type conduction. To directly investigate the Sb doping effect in ZnO, scanning capacitance microscopy (SCM) and scanning spreading resistance microscopy (SSRM) were performed on the NWs' cross-sections mapping their two dimensional (2D) local electrical properties. Although no direct p-type inversion in ZnO was revealed, a lower net electron concentration was pointed out for the Sb-doped ZnO shell layer with respect to the non-intentionally doped ZnO core, indicating an evident compensating effect as a result of the Sb incorporation, which can be ascribed to the formation of Sb-related acceptors. The results demonstrate SCM/SSRM investigation being a direct and effective approach for characterizing radial semiconductor one-dimensional (1D) structures and, particularly, for the doping study on the ZnO nanomaterial towards its p-type realization.

  5. Cross-section imaging and p-type doping assessment of ZnO/ZnO:Sb core-shell nanowires by scanning capacitance microscopy and scanning spreading resistance microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lin, E-mail: lin.wang@insa-lyon.fr; Brémond, Georges [Institut des Nanotechnologies de Lyon (INL), Université de Lyon, CNRS UMR 5270, INSA Lyon, Bat. Blaise Pascal, 7 Avenue, Jean Capelle, 69621 Villeurbanne (France); Sallet, Vincent; Sartel, Corinne [Groupe d' étude de la Matière Condensée (GEMaC), CNRS - Université de Versailles St Quentin en Yvelines, Université Paris-Saclay, 45 Avenue des Etats-Unis, 78035 Versailles (France)

    2016-08-29

    ZnO/ZnO:Sb core-shell structured nanowires (NWs) were grown by the metal organic chemical vapor deposition method where the shell was doped with antimony (Sb) in an attempt to achieve ZnO p-type conduction. To directly investigate the Sb doping effect in ZnO, scanning capacitance microscopy (SCM) and scanning spreading resistance microscopy (SSRM) were performed on the NWs' cross-sections mapping their two dimensional (2D) local electrical properties. Although no direct p-type inversion in ZnO was revealed, a lower net electron concentration was pointed out for the Sb-doped ZnO shell layer with respect to the non-intentionally doped ZnO core, indicating an evident compensating effect as a result of the Sb incorporation, which can be ascribed to the formation of Sb-related acceptors. The results demonstrate SCM/SSRM investigation being a direct and effective approach for characterizing radial semiconductor one-dimensional (1D) structures and, particularly, for the doping study on the ZnO nanomaterial towards its p-type realization.

  6. Irradiation and testbeam of KEK/HPK planar p-type pixel modules for HL-LHC

    Science.gov (United States)

    Nakamura, K.; Arai, Y.; Hagihara, M.; Hanagaki, K.; Hara, K.; Hori, R.; Hirose, M.; Ikegami, Y.; Jinnouchi, O.; Kamada, S.; Kawagoe, K.; Kohno, T.; Motohashi, K.; Nishimura, R.; Oda, S.; Otono, H.; Takubo, Y.; Terada, S.; Takashima, R.; Tojo, J.; Unno, Y.; Usui, J.; Wakui, T.; Yamaguchi, D.; Yamamoto, K.; Yamamura, K.

    2015-06-01

    For the ATLAS detector upgrade for the high luminosity LHC (HL-LHC), an n-in-p planar pixel sensor-module is being developed with HPK. The modules were irradiated at the Cyclotron RadioIsotope Center (CYRIC) using 70 MeV protons. For the irradiation, a novel irradiation box has been designed that carries 16 movable slots to irradiate the samples slot-by-slot independently, to reduce the time for replacing the samples by hand, thus reducing the irradiation to human body. The box can be moved horizontally and vertically to scan the samples for a maximum area of 11 cm × 11 cm. Tests were subsequently carried out with beam at CERN by using 120 GeV pions and at DESY with 4 GeV electrons. We describe the analyses of the testbeam data of the KEK/HPK sensor-modules, focussing on the comparison of the performance of old and new designs of pixel structures, together with a reference of the simplest design (no biasing structure). The novel design has shown comparably good performance as the no-structure design in detecting passing-through charged particles.

  7. Distinct role of Arabidopsis mitochondrial P-type pentatricopeptide repeat protein-modulating editing protein, PPME, in nad1 RNA editing.

    Science.gov (United States)

    Leu, Kuan-Chieh; Hsieh, Ming-Hsiun; Wang, Huei-Jing; Hsieh, Hsu-Liang; Jauh, Guang-Yuh

    2016-06-02

    The mitochondrion is an important power generator in most eukaryotic cells. To preserve its function, many essential nuclear-encoded factors play specific roles in mitochondrial RNA metabolic processes, including RNA editing. RNA editing consists of post-transcriptional deamination, which alters specific nucleotides in transcripts to mediate gene expression. In plant cells, many pentatricopeptide repeat proteins (PPRs) participate in diverse organellar RNA metabolic processes, but only PLS-type PPRs are involved in RNA editing. Here, we report a P-type PPR protein from Arabidopsis thaliana, P-type PPR-Modulating Editing (PPME), which has a distinct role in mitochondrial nad1 RNA editing via RNA binding activity. In the homozygous ppme mutant, cytosine (C)-to-uracil (U) conversions at both the nad1-898 and 937 sites were abolished, disrupting Arg(300)-to-Trp(300) and Pro(313)-to-Ser(313) amino acid changes in the mitochondrial NAD1 protein. NAD1 is a critical component of mitochondrial respiration complex I; its activity is severely reduced in the homozygous ppme mutant, resulting in significantly altered growth and development. Both abolished RNA editing and defective complex I activity were completely rescued by CaMV 35S promoter- and PPME native promoter-driven PPME genomic fragments tagged with GFP in a homozygous ppme background. Our experimental results demonstrate a distinct role of a P-type PPR protein, PPME, in RNA editing in plant organelles.

  8. P-type transparent conducting oxides

    Science.gov (United States)

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

    2016-09-01

    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 In2O3, Al doped ZnO, and F doped SnO2. 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 2p 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 2p orbitals with close-shell Cu 3d 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, Cr3+-based oxides (3d 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.

  9. Analysis of energy states in modulation doped multiquantum well heterostructures

    Science.gov (United States)

    Ji, G.; Henderson, T.; Peng, C. K.; Huang, D.; Morkoc, H.

    1990-01-01

    A precise and effective numerical procedure to model the band diagram of modulation doped multiquantum well heterostructures is presented. This method is based on a self-consistent iterative solution of the Schroedinger equation and the Poisson equation. It can be used rather easily in any arbitrary modulation-doped structure. In addition to confined energy subbands, the unconfined states can be calculated as well. Examples on realistic device structures are given to demonstrate capabilities of this procedure. The numerical results are in good agreement with experiments. With the aid of this method the transitions involving both the confined and unconfined conduction subbands in a modulation doped AlGaAs/GaAs superlattice, and in a strained layer InGaAs/GaAs superlattice are identified. These results represent the first observation of unconfined transitions in modulation doped multiquantum well structures.

  10. Poole-Frenkel effect on electrical characterization of Al-doped ZnO films deposited on p-type GaN

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Bohr-Ran [Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Liao, Chung-Chi [Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Ke, Wen-Cheng, E-mail: wcke@saturn.yzu.edu.tw; Chang, Yuan-Ching; Huang, Hao-Ping [Department of Mechanical Engineering, Yuan Ze University, Chung-Li 320, Taiwan (China); Chen, Nai-Chuan [Institute of Electro-Optical Engineering and Department of Electronic Engineering, Chang Gung University, Tao-Yuan 333, Taiwan (China)

    2014-03-21

    This paper presents the electrical properties of Al-doped ZnO (AZO) films directly grown on two types of p-type GaN thin films. The low-pressure p-GaN thin films (LP-p-GaN) exhibited structural properties of high-density edge-type threading dislocations (TDs) and compensated defects (i.e., nitrogen vacancy). Compared with high-pressure p-GaN thin films (HP-p-GaN), X-ray photoemission spectroscopy of Ga 3d core levels indicated that the surface Fermi-level shifted toward the higher binding-energy side by approximately 0.7 eV. The high-density edge-type TDs and compensated defects enabled surface Fermi-level shifting above the intrinsic Fermi-level, causing the surface of LP-p-GaN thin films to invert to n-type semiconductor. A highly nonlinear increase in leakage current regarding reverse-bias voltage was observed for AZO/LP-p-GaN. The theoretical fits for the reverse-bias voltage region indicated that the field-assisted thermal ionization of carriers from defect associated traps, which is known as the Poole-Frenkel effect, dominated the I-V behavior of AZO/LP-p-GaN. The fitting result estimated the trap energy level at 0.62 eV below the conduction band edge. In addition, the optical band gap increased from 3.50 eV for as-deposited AZO films to 3.62 eV for 300 °C annealed AZO films because of the increased carrier concentration. The increasing Fermi-level of the 300 °C annealed AZO films enabled the carrier transport to move across the interface into the LP-p-GaN thin films without any thermal activated energy. Thus, the Ohmic behavior of AZO contact can be achieved directly on the low-pressure p-GaN films at room temperature.

  11. Deposition of Na–N dual acceptor doped p-type ZnO thin films and fabrication of p-ZnO:(Na, N)/n-ZnO:Eu homojunction

    Energy Technology Data Exchange (ETDEWEB)

    Swapna, R., E-mail: swapna.ramella@yahoo.com; Santhosh Kumar, M.C., E-mail: santhoshmc@nitt.edu

    2013-09-20

    Highlights: • Low resistive and stable p-type ZnO films are fabricated by dual acceptor-doping. • The fabricated p-ZnO:(Na, N)/n-ZnO:Eu homojunction is characterized and discussed. • The fabricated ZnO homojunction shows good rectifying characteristics. • The fabricated ZnO homojunction is suitable for optoelectronic devices. -- Abstract: Sodium and nitrogen dual acceptor doped p-type ZnO (ZnO:(Na, N)) films have been prepared by spray pyrolysis technique at a substrate temperature of 623 K. The ZnO:(Na, N) films are grown at a fixed N doping concentration of 2 at.% and varying the nominal Na doping concentration from 0 to 8 at.%. The XRD results show that all the ZnO:(Na, N) films exhibited (0 0 2) preferential orientation. The EDX and elemental mapping analysis shows the presence and distribution of Zn, O, Na and N in the deposited films. The Hall measurement results demonstrate that the Na–N dual acceptor doped ZnO films show excellent p-type conduction. The p-type ZnO:(Na, N) films with comparatively low resistivity of 5.60 × 10{sup −2} Ω cm and relatively high carrier concentration of 3.15 × 10{sup 18} cm{sup −3} are obtained at 6 at.%. ZnO based homojunction is fabricated by depositing n-type layer (Eu doped ZnO) grown over the p-type layer ZnO:(Na, N). The current–voltage (I–V) characteristics measured from the two-layer structure show typical rectifying characteristics of p-n junction with a low turn on voltage of about 1.69 V. The ZnO:(Na, N) films exhibit a high transmittance (about >90%) and the average reflectance is 8.9% in the visible region. PL measurement shows near-band-edge (NBE) emission and deep-level (DL) emission in the ZnO:(Na, N) thin films.

  12. Na-Diffusion Enhanced p-type Conductivity in Cu(In,Ga)Se 2 : A New Mechanism for Efficient Doping in Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Zhen-Kun [Key Laboratory for Computational Physical Sciences (MOE), State Key Laboratory of Surface Physicsand Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 China; Chen, Shiyou [Key Laboratory of Polar Materials and Devices (MOE), East China Normal University, Shanghai 200241 China; Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan Shanxi 030006 China; Xie, Yun [Key Laboratory for Computational Physical Sciences (MOE), State Key Laboratory of Surface Physicsand Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 China; Park, Ji-Sang [National Renewable Energy Laboratory, Golden CO 80401 USA; Xiang, Hongjun [Key Laboratory for Computational Physical Sciences (MOE), State Key Laboratory of Surface Physicsand Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 China; Gong, Xin-Gao [Key Laboratory for Computational Physical Sciences (MOE), State Key Laboratory of Surface Physicsand Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 China; Wei, Su-Huai [Beijing Computational Science Research Center, Beijing 100094 China

    2016-08-30

    A new mechanism responsible for the hole concentration increase in the CIGS thin films after Na doping is proposed. At high temperature, a high concentration of Na is doped into the grains. After cooling and water rinsing, the solubility of Na becomes lower, so Na diffuses out of the grains with high concentration of Cu vacancies and hole carriers formed.

  13. The design of Cu-doped ZnO thermoelectric module (simulation study)

    Science.gov (United States)

    Hadi, Syamsul; Suratwan, Agus; Kurniawan, Agus; Budiana, Eko Prasetya; Suyitno

    2016-03-01

    The p-type semiconductor of Cu-doped ZnO-based thermoelectric material has already been synthesized and studied as an energy harvester. The next challenge is manufacturing the thermoelectric module in the development of thermoelectric as an eco-friendly material in the future. This research aims to investigate the effect of thermoelectric geometric design on the electrical output power and voltage and to recommend the most appropriate thermoelectric geometric design. The design of thermoelectric generator (TEG) includes the determinations of dimension (width, length, and height), number of modules, and semiconductor materials. The simulation used the coupled-field analysis of ANSYS APDL 14.5 in the steady state condition. The p- and n- type thermoelectric material used Cu-doped ZnO and Al-doped ZnO, respectively. The width of element and the number of thermoelectric module were varied to obtain a thermoelectric design, which produces the largest current, power, and voltage. The result of research shows that the t hermoelectric generator with the element widths of 0.94 mm, 1.125 mm, 1.05 mm, and 1.2 mm generates the largest power output and voltage, namely: 0.32 W and 0.89 V, 0.38 W and 0.98 V, 0.45 W and 1.06 V, and 0.52 W and 1.13 V, respectively.

  14. Impact of common metallurgical impurities on ms-Si solar cell efficiency. P-type versus n-type doped ingots

    Energy Technology Data Exchange (ETDEWEB)

    Geerligs, L.J.; Manshanden, P. [ECN Solar Energy, Petten (Netherlands); Solheim, I.; Ovrelid, E.J.; Waernes, A.N. [Sintef materials technology, Trondheim (Norway)

    2006-09-15

    Silicon solar cells based on n-type silicon wafers are less sensitive to carrier lifetime degradation due to several common metal impurities than p-base cells. The theoretical and experimental indications for this have recently received considerable attention. This paper compares p-type and n-type cells purposely contaminated with relatively high levels of impurities, processed by industrial techniques. The impurities considered are Al, Ti, and Fe, which are the dominant impurities in metallurgical silicon and natural quartz. The work also preliminary addresses the question whether the optimal wafer resistivity is the same for n-type as for p-type base mc-Si cells.

  15. Influence of film thickness and oxygen partial pressure on cation-defect-induced intrinsic ferromagnetic behavior in luminescent p-type Na-doped ZnO thin films.

    Science.gov (United States)

    Ghosh, S; Khan, Gobinda Gopal; Varma, Shikha; Mandal, K

    2013-04-10

    In this article, we have investigated the effect of oxygen partial pressure (PO2) and film thickness on defect-induced room-temperature (RT) ferromagnetism (FM) of highly c-axis orientated p-type Na-doped ZnO thin films fabricated by pulse laser deposition (PLD) technique. We have found that the substitution of Na at Zn site (NaZn) can be effective to stabilize intrinsic ferromagnetic (FM) ordering in ZnO thin films with Curie temperature (TC) as high as 509 K. The saturation magnetization (MS) is found to decrease gradually with the increase in thickness of the films, whereas an increase in "MS" is observed with the increase in PO2 of the PLD chamber. The enhancement of ferromagnetic signature with increasing PO2 excludes the possibility of oxygen vacancy (VO) defects for the magnetic origin in Na-doped ZnO films. On the other hand, remarkable enhancement in the green emission (IG) are observed in the photoluminescence (PL) spectroscopic measurements due to Na-doping and that indicates the stabilization of considerable amount of Zn vacancy (VZn)-type defects in Na-doped ZnO films. Correlating the results of PL and X-ray photoelectron spectroscopy (XPS) studies with magnetic measurements we have found that VZn and Na substitutional (NaZn) defects are responsible for the hole-mediated FM in Na-doped ZnO films, which might be an effective candidate for modern spintronic technology.

  16. Tight-binding study of the hole subband structure properties of p-type delta-doped quantum wells in Si by using a Thomas-Fermi-Dirac potential

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Vargas, I; Madrigal-Melchor, J; Vlaev, S J, E-mail: isaac@planck.reduaz.m [Unidad Academica de Fisica, Universidad Autonoma de Zacatecas, Calzada Solidaridad Esquina Con Paseo La Bufa S/N, 98060 Zacatecas, ZAC. (Mexico)

    2009-05-01

    We present the hole subband structure of p-type delta-doped single, double, multiple and superlattice quantum wells in Si. We use the first neighbors sp{sup 3}s' tight-binding approximation including spin for the hole level structure analysis. The parameters of the tight-binding hamiltonian were taken from Klimeck et al. [Klimeck G, Bowen R C, Boykin T B, Salazar-Lazaro C, Cwik T A and Stoica A 2000 Superlattice. Microst. 27 77], first neighbors parameters that give realiable results for the valence band of Si. The calculations are based on a scheme previously proposed and applied to delta-doped quantum well systems [Vlaev S J and Gaggero-Sager L M 1998 Phys. Rev. B 58 1142]. The scheme relies on the incorporation of the delta-doped quantum well potential in the diagonal terms of the tight-binding hamiltonian. We give a detail description of the delta-doped quantum well structures, this is, we study the hole subband structure behavior as a function of the impurity density, the interwell distance of the doped planes and the superlattice period. We also compare our results with the available theoretical and experimental data, obtaining a reasonable agreement.

  17. Preparation and Properties of N-Doped p-Type ZnO Films by Solid-Source Chemical Vapour Deposition with the c-Axis Parallel to the Substrate

    Institute of Scientific and Technical Information of China (English)

    吕建国; 叶志镇; 汪雷; 赵炳辉; 黄靖云

    2002-01-01

    We report on N-doped p-type ZnO films with the c-axis parallel to the substrate. ZnO films were prepared onan α-A12O3 (0001) substrate by solid-source chemical vapour deposition (CVD). Zn( CH3COO)2.2H2O was usedas the precursor and CH3COONH4 as the nitrogen source. The growth temperature was varied from 300℃ C to600℃ C. The as-grown ZnO film deposited at 500° C showed p-type conduction with its resistivity of 42 Ωcrm, carrierdensity 3.7 × 1017 cm-3 and Hall mobility 1.26cm2V-1.s-1 at room temperature, which are the best propertiesfor p-type ZnO deposited by CVD. The p-type ZnO film possesses a transmittance of about 85% in the visibleregion and a bandgap of 3.21 eV at room temperature.

  18. Realization of Ultraviolet Electroluminescence from ZnO Homo junction Fabricated on Silicon Substrate with p-Type ZnO:N Layer Formed by Radical N2O Doping

    Institute of Scientific and Technical Information of China (English)

    SUN Jing-Chang; LIANG Hong-Wei; ZHAO Jian-Ze; BIAN Ji-Ming; FENG Qiu-Ju; WANG Jing-Wei; ZHAO Zi-Wen; DU Guo-Tong

    2008-01-01

    @@ ZnO homojunction light-emitting diodes are fabricated on Si(100) substrates by plasma assisted metal organic chemical vapour deposition, A p-type layer of nitrogen-doped ZnO film is formed using radical N2O as the acceptor precursor.The n-type ZnO layer is composed of un-doped ZnO film.The device exhibits desirable rectifying behaviour with a turn-on voltage of 3.3 V and a reverse breakdown voltage higher than 6 V.Distinct electroluminescence emissions centred at 395nm and 49Ohm are detected from this device at forvcard current higher than 20mA at room temperature.

  19. Photo-Doped Active Electrically Controlled Terahertz Modulator

    Institute of Scientific and Technical Information of China (English)

    Bo Zhang; Liang Zhong; Ting He; Jing-Ling Shen

    2015-01-01

    We demonstrate an electric-controlled terahertz (THz) modulator which can be used to realize amplitude modulation of terahertz waves with slight photo-doping. The THz pulse transmission was efficiently modulated by electrically controlling the monolayer silicon-based device. The modulation depth reached 100% almost when the applied voltage was 7V at an external laser intensity of 0.6W/cm2. The saturation voltage reduced with the increase of the photo-excited intensity. In a THz continuous wave (CW) system, a significant fall in both THz transmission and reflection was also observed with the increase of applied voltage. This reduction in the THz transmission and reflection was induced by the absorption for electron injection. The results show that a high-efficiency and high modulation depth broadband electric-controlled terahertz modulator in a pure Si structure has been realized.

  20. Modulating Hole Transport in Multilayered Photocathodes with Derivatized p-Type Nickel Oxide and Molecular Assemblies for Solar-Driven Water Splitting

    Energy Technology Data Exchange (ETDEWEB)

    Shan, Bing; Sherman, Benjamin D.; Klug, Christina; Nayak, Animesh; Marquard, Seth; Liu, Qing; Bullock, Ronald M.; Meyer, Thomas J.

    2017-08-30

    We report here a new photocathode composed of a bi-layered doped NiO film topped by a macro-mesoporous ITO (ioITO) layer with molecular assemblies attached to the ioITO surface. The NiO film containing a 2% K+ doped NiO inner layer and a 2% Cu2+ doped NiO outer layer provides sufficient driving force for hole transport after injection to NiO by the molecular assembly. The tri-layered oxide, NiK0.02O | NiCu0.02O | ioITO, sensitized by a ruthenium polypyridyl dye and functionalized with a nickel-based hydrogen evolution catalyst, outperforms its counterpart, NiO | NiO | ioITO, in photocatalytic hydrogen evolution from water over a period of several hours with a Faradaic yield of ~90%.

  1. Laser characterisation of a 3D single-type column p-type prototype module read out with ATLAS SCT electronics

    Energy Technology Data Exchange (ETDEWEB)

    Ehrich, T. [Physikalisches Institut, Universitaet Freiburg, Hermann-Herder Str. 3, 79104 Freiburg (Germany); Kuehn, S. [Physikalisches Institut, Universitaet Freiburg, Hermann-Herder Str. 3, 79104 Freiburg (Germany)], E-mail: susanne.kuehn@physik.uni-freiburg.de; Boscardin, M.; Dalla Betta, G.-F. [ITC-irst Trento, Microsystems Division, via Sommarive, 18 38050 Povo di Trento (Italy); Eckert, S.; Jakobs, K.; Maassen, M.; Parzefall, U. [Physikalisches Institut, Universitaet Freiburg, Hermann-Herder Str. 3, 79104 Freiburg (Germany); Piemonte, C.; Pozza, A.; Ronchin, S.; Zorzi, N. [ITC-irst Trento, Microsystems Division, via Sommarive, 18 38050 Povo di Trento (Italy)

    2007-12-11

    In this paper measurements of a 3D single-type column (3D-stc) microstrip silicon device are shown. The 3D-stc sensor has n-type columns in p-type substrate. It has been connected to an ATLAS SCT ABCD3T chip and is readout with ATLAS SCT electronics at 40 MHz. Spatial measurements were done with a laser setup to investigate the expected low field region in 3D devices. An influence of the p-stops on the collected charge has been observed.

  2. The effect of δ-doping and modulation-doping on Si-doped high Al content n-AlxGa1-xN grown by MOCVD

    Institute of Scientific and Technical Information of China (English)

    Zhu Shaoxin; Yan Jianchang; Zeng Jianping; Zhang Ning; Si Zhao; Dong Peng; Li Jinmin

    2013-01-01

    The effect of periodic delta-doping and modulation-doping on high Al content n-AlxGa1-xN (x =0.55) epilayers grown by MOCVD has been investigated.Measured by XRD,AFM,contactless sheet resistance,and Hall-effect tests,δ-doped and modulation-doped n-AlxGa1-xN have better crystal quality,surface morphology and electrical properties as compared with uniformly-doped n-AlxGa1-xN.These improvements are attributed to the SiNx growth mask induced by δ-doping layers and the dislocation-blocking effect induced by both growth techniques.In addition,due to the broadened doping profile ascribed to enhanced dopant diffusion at high growth temperatures (1150 ℃) of n-Al0.55Ga0.45N,modulation-doped n-Al0.55Ga0.45N has similar properties as δ-doped n-Al0.55Ga0.45N.

  3. Nanoscopic oxidation of p-type and un-doped Si (100) surfaces using un-externally biased atomic force microscope tips (AFM) in the presence of selected organic solvents

    Science.gov (United States)

    McCausland, Jeffrey; Withanage, Sajeevi; Mallik, Robert; Lyuksyutov, Sergei

    A conductive un-biased AFM tip oscillating above p-type or un-doped Si (100) treated with toluene, butan-2-ol, and propan-2-ol creates nanostructures ranging in height from 1-100 nm. The tip was oscillated in ambient conditions (30-70% Rel. Humidity) at frequencies in the 102 kHz range. It was repeatable with various concentrations of solvent in aqueous solution. It is suggested that mechanical oscillations of the AFM tip polarizes the solvent molecules deposited on the surface resulting in electron transfer from the tip to the surface followed by feature formation. This process effectively creates an electrochemical cell at the microscopic level and the miscibility of the solvents is the key to enabling the process. Species which ionize during the process may be consumed in irreversible reactions whereas the alcohols act as catalysts and are not consumed. The influence of boron defects in the Si substrates is also discussed. It appears that the observed oxidation is different from all other similar reported phenomena including local anodic oxidation, and chemo-mechanical lithographic techniques utilizing AFM.

  4. MOVPE of n-doped GaAs and modulation doped GaAs/AlGaAs nanowires

    Science.gov (United States)

    Sladek, K.; Klinger, V.; Wensorra, J.; Akabori, M.; Hardtdegen, H.; Grützmacher, D.

    2010-02-01

    Two different fabrication approaches were compared to obtain conductive GaAs nanowires: on one hand by modulation doping of GaAs/AlGaAs core/shell nanowires, on the other hand by Si-doping of GaAs nanowires. Modulation doped GaAs/AlGaAs core-shell nanowires were grown by selective area metal organic vapor phase epitaxy (MOVPE) on GaAs (1 1 1) substrates. The influences of growth parameters and mask design on aspect ratio of the core structures were investigated. The specialty of this study was that the growth mode was switched from vertical GaAs wire growth to the AlGaAs conformal shell overgrowth by intentionally changing the growth chemistry from the use of a more stable group III source - trimethylgallium (TMGa) to more easily decomposed sources - the alternative sources triethylgallium (TEGa) and dimethylethylaminealane (DMEAAl). It was found that the diameter and length of the core structures strongly depend on the arsenic partial pressure and growth temperature as well as mask design. The uniformity of shell growth is also influenced by the mask design. Additionally an alternative approach for the production of conductive GaAs nanowires was under study. To this end, the influence of Si-doping on GaAs core growth was investigated. It was found that doping has a detrimental impact on growth morphology leading to an undesirable enhanced growth rate on the nanowire side facets.

  5. Locking of self-oscillation frequency by pump modulation in an erbium-doped fiber laser

    Science.gov (United States)

    Pisarchik, A. N.; Barmenkov, Yu. O.

    2005-10-01

    Frequency locking of self-oscillations in a diode-pumped erbium-doped fiber laser by external modulation of the diode current is studied experimentally. The coexistence of locking and unlocking regimes is detected. The condition for onset of the bistability and dependences of the frequency detuning on the modulation frequency and amplitude are established. Transitions to torus-chaos are also demonstrated.

  6. Active mode-locking via pump modulation in a Tm-doped fiber laser

    Directory of Open Access Journals (Sweden)

    Yu Wang

    2016-10-01

    Full Text Available We propose and experimentally realize a new class of actively mode-locking technique using pump modulation for rare-earth doped fiber lasers. A Tm-doped fiber laser at 2 μm is mode-locked using the proposed active mode-locking via pump modulation technique. Low-threshold continuous-wave mode-locking is achieved with a transform-limited pulse width of 4.4 ps, a spectral bandwidth of 0.9 nm, and a repetition rate of 12.9 MHz. Second-harmonic mode-locking is also demonstrated by simply driving the pump current at an appropriate frequency. More importantly, we believe that this technique can be applied to mode-lock other rare-earth doped fiber laser systems such as erbium- and ytterbium-doped fiber lasers.

  7. Hidden phase in a two-dimensional Sn layer stabilized by modulation hole doping

    Science.gov (United States)

    Ming, Fangfei; Mulugeta, Daniel; Tu, Weisong; Smith, Tyler S.; Vilmercati, Paolo; Lee, Geunseop; Huang, Ying-Tzu; Diehl, Renee D.; Snijders, Paul C.; Weitering, Hanno H.

    2017-03-01

    Semiconductor surfaces and ultrathin interfaces exhibit an interesting variety of two-dimensional quantum matter phases, such as charge density waves, spin density waves and superconducting condensates. Yet, the electronic properties of these broken symmetry phases are extremely difficult to control due to the inherent difficulty of doping a strictly two-dimensional material without introducing chemical disorder. Here we successfully exploit a modulation doping scheme to uncover, in conjunction with a scanning tunnelling microscope tip-assist, a hidden equilibrium phase in a hole-doped bilayer of Sn on Si(111). This new phase is intrinsically phase separated into insulating domains with polar and nonpolar symmetries. Its formation involves a spontaneous symmetry breaking process that appears to be electronically driven, notwithstanding the lack of metallicity in this system. This modulation doping approach allows access to novel phases of matter, promising new avenues for exploring competing quantum matter phases on a silicon platform.

  8. Electrical Properties of Photodiode Ba0.25Sr0.75TiO3 (BST Thin Film Doped with Ferric Oxide on p-type Si (100 Substrate using Chemical Solution Deposition Method

    Directory of Open Access Journals (Sweden)

    Irzaman

    2011-12-01

    Full Text Available In this paper we have grown pure Ba0.25Sr0.75TiO3 (BST and BST doped by Ferric Oxide Fe2O3 (BFST with doping variations of 5%, 10%, and 15% above type-p Silicon (100 substrate using the chemical solution deposition (CSD method with spin coating technique at rotation speed of 3000 rpm, for 30 seconds. BST thin film are made with a concentration of 1 M 2-methoxyethanol and annealing temperature of 850OC for the Si (100 substrate. Characterization of the thin film is performed for the electrical properties such as the current-voltage (I-V curve using Keithley model 2400 as well as dielectric constant, time constant, pyroelectric characteristics, and depth measurement. The results show that the thin film depth increases if the concentration of the Ferric Oxide doping increases. The I-V characterization shows that the BST and BFST thin film has photodiode properties. The dielectric constant increases with the addition of doping. The maximum dielectric constant value is obtained for 15 % doping concentration namely 83.1 for pure BST and 6.89, 11.1, 41.63 and 83.1, respectively for the Ferric Oxide doping based BST with concentration of 5%, 10%, and 15%. XRD spectra of 15 % of ferric oxide doped BST thin film tetragonal phase, we carried out the lattice constant were a = b = 4.203 Å; c = 4.214 Å; c/a ratio = 1.003

  9. Novel Electro-Optical Modulator Utilizing GeO2-Doped Silica Waveguide

    Institute of Scientific and Technical Information of China (English)

    LI Jiusheng; JIA Dagong

    2009-01-01

    In order to achieve a modulator with broad bandwidth and perfect impedance match,a novel electro-optical modulator based on GeO2-doped silica waveguides on silicon substrate is designed.The finite element model of the whole electro-optical modulator is established by means of ANSYS.With the finite element method analysis,the performance of the novel modulator is predicted.The simulation reveals that the designed modulator operates with a product of 3 dB optical bandwidth and modulating length of 226.59 GHz-cm,and a characteristic impedance of 51.6 Ω at 1 550 nm wavelength.Moreover,the calculated electrical reflected power of coplanar waveguide electrode is below -20 dB in the frequency ranging from 45 MHz to 65 GHz.Therefore,the designed modulator has wide modulation bandwidth and perfect impedance match.

  10. Magnetic modulation doping in topological insulators toward higher-temperature quantum anomalous Hall effect

    Energy Technology Data Exchange (ETDEWEB)

    Mogi, M., E-mail: mogi@cmr.t.u-tokyo.ac.jp; Yoshimi, R.; Yasuda, K.; Kozuka, Y. [Department of Applied Physics and Quantum Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan); Tsukazaki, A. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); PRESTO, Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-0075 (Japan); Takahashi, K. S. [RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan); Kawasaki, M.; Tokura, Y. [Department of Applied Physics and Quantum Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan); RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan)

    2015-11-02

    Quantum anomalous Hall effect (QAHE), which generates dissipation-less edge current without external magnetic field, is observed in magnetic-ion doped topological insulators (TIs) such as Cr- and V-doped (Bi,Sb){sub 2}Te{sub 3}. The QAHE emerges when the Fermi level is inside the magnetically induced gap around the original Dirac point of the TI surface state. Although the size of gap is reported to be about 50 meV, the observable temperature of QAHE has been limited below 300 mK. We attempt magnetic-Cr modulation doping into topological insulator (Bi,Sb){sub 2}Te{sub 3} films to increase the observable temperature of QAHE. By introducing the rich-Cr-doped thin (1 nm) layers at the vicinity of both the surfaces based on non-Cr-doped (Bi,Sb){sub 2}Te{sub 3} films, we have succeeded in observing the QAHE up to 2 K. The improvement in the observable temperature achieved by this modulation-doping appears to be originating from the suppression of the disorder in the surface state interacting with the rich magnetic moments. Such a superlattice designing of the stabilized QAHE may pave a way to dissipation-less electronics based on the higher-temperature and zero magnetic-field quantum conduction.

  11. Nonlinear resonance phenomena of a doped fibre laser under cavity-loss modulation: Experimental demonstrations

    Indian Academy of Sciences (India)

    A Ghosh; B K Goswami; R Vijaya

    2010-11-01

    Our experiments with an erbium-doped fibre ring laser (CW, single transverse mode and multiaxial mode) with an intracavity LiNbO3 electro-optic modulator (EOM) display the characteristic features of a nonlinear oscillator (e.g., harmonic and period-2 sub-harmonic resonances) when the EOM driver voltage is modulated periodically. Harmonic resonance leads to period-1 bistability and hysteresis. Inside the period-2 sub-harmonic resonance region, the laser exhibits Feigenbaum sequence and generalized bistability.

  12. Modulating doping and interface magnetism of epitaxial graphene on SiC(0001)

    Science.gov (United States)

    Pan, Zhou; Da-Wei, He

    2016-01-01

    On the basis of first principles calculations, we report that the type and density of charge carriers of epitaxial graphene on SiC(0001) can be deliberately controlled by decorating the buffer layer with specific atoms (i.e., F, Cl, O, or N). More importantly, a fine tuning of the doping behavior from intrinsic n-type to charge neutrality to p-type and interface magnetism is achieved via increasing the doping concentration of F atoms on the buffer layer. Our results suggest an interesting avenue to the application of epitaxial graphene in nanoscale electronic and spintronic devices. Project supported by the National Natural Science Foundation of China (Grant Nos. 61335006, 61378073, and 61527817), the Beijing Municipal Science and Technology Committee, China (Grant No. Z151100003315006), and Fundamental Research Funds for the Central Universities of Beijing Jiaotong University, China (Grant No. 2012YJS123).

  13. Growth of GaN on sapphire via low-temperature deposited buffer layer and realization of p-type GaN by Mg doping followed by low-energy electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Amano, Hiroshi [Department of Electrical Engineering and Computer Science, Venture Business Laboratory, Akasaki Research Center, Nagoya University (Japan)

    2015-06-15

    This is a personal history of one of the Japanese researchers engaged in developing a method for growing GaN on a sapphire substrate, paving the way for the realization of smart television and display systems using blue LEDs. The most important work was done in the mid to late 1980s. The background to the author's work and the process by which the technology enabling the growth of GaN and the realization of p-type GaN was established are reviewed. (copyright 2015 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Modulation Doping of Silicon using Aluminium-induced Acceptor States in Silicon Dioxide

    Science.gov (United States)

    König, Dirk; Hiller, Daniel; Gutsch, Sebastian; Zacharias, Margit; Smith, Sean

    2017-04-01

    All electronic, optoelectronic or photovoltaic applications of silicon depend on controlling majority charge carriers via doping with impurity atoms. Nanoscale silicon is omnipresent in fundamental research (quantum dots, nanowires) but also approached in future technology nodes of the microelectronics industry. In general, silicon nanovolumes, irrespective of their intended purpose, suffer from effects that impede conventional doping due to fundamental physical principles such as out-diffusion, statistics of small numbers, quantum- or dielectric confinement. In analogy to the concept of modulation doping, originally invented for III-V semiconductors, we demonstrate a heterostructure modulation doping method for silicon. Our approach utilizes a specific acceptor state of aluminium atoms in silicon dioxide to generate holes as majority carriers in adjacent silicon. By relocating the dopants from silicon to silicon dioxide, Si nanoscale doping problems are circumvented. In addition, the concept of aluminium-induced acceptor states for passivating hole selective tunnelling contacts as required for high-efficiency photovoltaics is presented and corroborated by first carrier lifetime and tunnelling current measurements.

  15. Dynamics of an erbium-doped fiber laser with pump modulation: theory and experiment

    Science.gov (United States)

    Pisarchik, Alexander N.; Kir'yanov, Alexander V.; Barmenkov, Yuri O.; Jaimes-Reátegui, Rider

    2005-10-01

    We study in detail the complex dynamics of an erbium-doped fiber laser that has been subjected to harmonic modulation of a diode pump laser. We introduce a novel laser model that describes perfectly all experimentally observed features. The model is generalized to a nonlinear oscillator. The coexistence of different periodic and chaotic regimes and their relation to subharmonics and higher harmonics of the relaxation oscillation frequency of the laser are demonstrated with codimensional-one and codimensional-two bifurcation diagrams in parameter space of the modulation frequency and amplitude. The phase difference between the laser response and the pump modulation is also investigated.

  16. Pump-induced refractive index modulation and dispersions in Er3+-doped fibers

    DEFF Research Database (Denmark)

    Thirstrup, Carsten; Shi, Yuan

    1996-01-01

    A novel measurement system provides determination of pump induced phase shifts in erbium doped fibers with an accuracy of ~π/20. Using this system, a systematical analysis of the pump induced modulation of the refractive index and dispersions for a signal at 1550 nm and a pump at 980 nm is reported....... The analysis contains measurements of pump induced refractive index changes as function of wavelength, pump power, and doping concentration. A model taking account of the contribution to the refractive index changes from optical transitions between 4 I15/2 states and 4I13/2 states in Er3+ yields good agreement...

  17. Beyond modulation doping: Engineering a semiconductor to be ambipolar, or making an ON-OFF-ON transistor

    Science.gov (United States)

    Gupta, K. Das; Croxall, A. F.; Zheng, B.; Sfigakis, F.; Farrer, I.; Nicoll, C. A.; Beere, H. E.; Ritchie, D. A.

    2014-04-01

    Semiconductors are traditionaly either p-type or n-type, meaning that the mobile charge carriers in them are either "holes" in the valence band or electrons in the conduction band. Ambipolar conduction implies that the experimenter should be able to populate the same channel with either electrons or holes in a controlled manner. This has been shown to be possible in newer materials like Graphene and some organic semiconductors. "Ambipolarity" can open up new device possibilities as well as new ways to study fundamental scattering mechanisms in semiconductors. However, achieving this in a conventional high mobility structure like a GaAs-AlGaAs heterostructure/quantum well requires new thinking. It was realized, that to do this modulation doping must be given up and techniques to make an undoped heterostructure conduct, must be developed first. Such structures have been developed by only a few groups worldwide. They are of great interest to low temperature physicists working with Quantum Hall states and mesoscopic/nano structures in the ballistic regime. We discuss the reason behind this interest and the analysis of scattering mechanisms in such structures. Finally very recent experimental success in developing fully gate controlled ambipolar structures where both electron and hole mobilites exceed 1 million cm2/Vs at low temperatures (T˜1Kelvin) are discussed. Such gated ambipolar structures can be used to analyse scattering mechanisms in ultra-high mobility 2dimensional electron and hole gases in a way that is not possible using other techniques.

  18. Light and current induced degradation in p-type multi-crystalline cells and development of an inspection method and a stabilization method

    Energy Technology Data Exchange (ETDEWEB)

    Broek, K.M.; Bennett, I.J.; Jansen, M.J.; Borg, Van der N.J.C.M.; Eerenstein, W. [ECN Solar Energy, Petten (Netherlands)

    2012-09-15

    Stable solar cells are needed for durability testing of different combinations of module materials. In such a test, significant power losses in full-size modules with multi-crystalline cells after thermal cycling have been observed. This has been related to degradation of the solar cells used and it appeared that this was caused by current induced degradation. This phenomenon is not limited to boron doped Cz-Si, but can also occur in p-type multi-crystalline silicon. Work was done to develop an incoming inspection method for new batches of cells. Also, stabilisation procedures for modules containing cells that are sensitive to degradation have been determined.

  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. Photoluminescence of anti-modulation doped near-surface GaAs/AlGaAs single quantum well structures exposed to hydrogen plasma

    CERN Document Server

    Bumaj, Y A; Goldkhan, R; Shtajn, N; Golombek, A; Nakov, V; Cheng, T S

    2002-01-01

    The anti-modulation Si-doped GaAs/AlGaAs structures with near-surface single quantum wells grown by molecular-beam epitaxy were exposed to hydrogen plasma at 260 deg C and investigated by low-temperature photoluminescence, photoluminescence excitation and photoreflectance spectroscopy. After hydrogenation, the quenching of the exciton luminescence for the below AlGaAs band gap excitation due to the increase of electric field in the structure has been observed. The effect is consistent with unpinning of Fermi level from mid gap of nominally undoped (p-type) GaAs cap layer due to passivation of surface states by hydrogen without neutralization of shallow impurities in the epilayers

  1. Large Modulation of Charge Carrier Mobility in Doped Nanoporous Organic Transistors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fengjiao [Department of Chemical and Biomolecular Engineering, University of Illinois Urbana-Champaign, 600 S. Mathews Ave. Urbana IL 61801 USA; Dai, Xiaojuan [Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 P. R. China; Zhu, Weikun [Department of Chemical and Biomolecular Engineering, University of Illinois Urbana-Champaign, 600 S. Mathews Ave. Urbana IL 61801 USA; Chung, Hyunjoong [Department of Chemical and Biomolecular Engineering, University of Illinois Urbana-Champaign, 600 S. Mathews Ave. Urbana IL 61801 USA; Diao, Ying [Department of Chemical and Biomolecular Engineering, University of Illinois Urbana-Champaign, 600 S. Mathews Ave. Urbana IL 61801 USA

    2017-05-10

    Molecular doping of organic electronics has shown promise to sensitively modulate important device metrics. One critical challenge is the disruption of structure order upon doping of highly crystalline organic semiconductors, which significantly reduces the charge carrier mobility. This paper demonstrates a new method to achieve large modulation of charge carrier mobility via channel doping without disrupting the molecular ordering. Central to the method is the introduction of nanopores into the organic semiconductor thin films via a simple and robust templated meniscus-guided coating method. Using this method, the charge carrier mobility of C8-benzothieno[3,2-b]benzothiophene transistors is boosted by almost sevenfold. This paper further demonstrates enhanced electron transport by close to an order of magnitude in a diketopyrrolopyrrole-based donor–acceptor polymer. Combining spectroscopic measurements, density functional theory calculations, and electrical characterizations, the doping mechanism is identified as partial-charge-transfer induced trap filling. The nanopores serve to enhance the dopant/organic semiconductor charge transfer reaction by exposing the π-electrons to the pore wall.

  2. Modulation-Doped In2O3/ZnO Heterojunction Transistors Processed from Solution

    KAUST Repository

    Khim, Dongyoon

    2017-03-15

    This paper reports the controlled growth of atomically sharp In2 O3 /ZnO and In2 O3 /Li-doped ZnO (In2 O3 /Li-ZnO) heterojunctions via spin-coating at 200 °C and assesses their application in n-channel thin-film transistors (TFTs). It is shown that addition of Li in ZnO leads to n-type doping and allows for the accurate tuning of its Fermi energy. In the case of In2 O3 /ZnO heterojunctions, presence of the n-doped ZnO layer results in an increased amount of electrons being transferred from its conduction band minimum to that of In2 O3 over the interface, in a process similar to modulation doping. Electrical characterization reveals the profound impact of the presence of the n-doped ZnO layer on the charge transport properties of the isotype In2 O3 /Li-ZnO heterojunctions as well as on the operating characteristics of the resulting TFTs. By judicious optimization of the In2 O3 /Li-ZnO interface microstructure, and Li concentration, significant enhancement in both the electron mobility and TFT bias stability is demonstrated.

  3. Enhanced thermoelectric properties in p-type Bi{sub 0.4}Sb{sub 1.6}Te{sub 3} alloy by combining incorporation and doping using multi-scale CuAlO{sub 2} particles

    Energy Technology Data Exchange (ETDEWEB)

    Song, Zijun; Liu, Yuan; Zhou, Zhenxing; Lu, Xiaofang; Wang, Lianjun [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai (China); Institute of Functional Materials, Donghua University, Shanghai (China); Zhang, Qihao [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai (China); University of Chinese Academy of Sciences, Beijing (China); Jiang, Wan [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai (China); Institute of Functional Materials, Donghua University, Shanghai (China); School of Material Science and Engineering, Jingdezhen Ceramic Institute, Jingdezhen (China); Chen, Lidong [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai (China)

    2017-01-15

    Multi-scale CuAlO{sub 2} particles are introduced into the Bi{sub 0.4}Sb{sub 1.6}Te{sub 3} matrix to synergistically optimize the electrical conductivity, Seebeck coefficient, and the lattice thermal conductivity. Cu element originating from fine CuAlO{sub 2} grains diffuses into the Bi{sub 0.4}Sb{sub 1.6}Te{sub 3} matrix and tunes the carrier concentration while the coarse CuAlO{sub 2} particles survive as the second phase within the matrix. The power factor is improved at the whole temperatures range due to the low-energy electron filtering effect on Seebeck coefficient and enhanced electrical transport property by mild Cu doping. Meanwhile, the remaining CuAlO{sub 2} inclusions give rise to more boundaries and newly built interfaces scattering of heat-carrying phonons, resulting in the reduced lattice thermal conductivity. Consequently, the maximum ZT is found to be enhanced by 150% arising from the multi-scale microstructure regulation when the CuAlO{sub 2} content reaches 0.6 vol.%. Not only that, but the ZT curves get flat in the whole temperature range after introducing the multi-scale CuAlO{sub 2} particles, which leads to a remarkable increase in the average ZT. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Low operation voltage of GaN-based LEDs with Al-doped ZnO upper contact directly on p-type GaN without insert layer

    Science.gov (United States)

    Chen, P. H.; Chen, Yu An; Chang, L. C.; Lai, W. C.; Kuo, Cheng Huang

    2015-07-01

    Al-doped ZnO (AZO) film was evaporated on double-side polished sapphire, p-GaN layers, n+-InGaN-GaN short-period superlattice (SPS) structures, and GaN-based light-emitting diodes (LEDs) by e-beam. The AZO film on the p-GaN layer after thermal annealing exhibited an extremely high transparency (98% at 450 nm) and a small specific contact resistance of 2.19 × 10-2 Ω cm2, which was almost the same as that of as-deposited AZO on n+-SPS structure. With 20 mA injection current, the forward voltages were 3.30 and 3.27 V, whereas the output powers were 4.32 and 4.07 mW for the LED with AZO on insert n+-SPS upper contact and the LED with AZO on p-GaN upper contact (without insert layer), respectively. The small specific contact resistance and low operation voltage of LED with AZO on p-GaN upper contact was achieved by rapid thermal annealing (RTA) process.

  5. Coulomb-interaction induced coupling of Landau levels in intrinsic and modulation-doped quantum wells

    Science.gov (United States)

    Paul, J.; Stevens, C. E.; Zhang, H.; Dey, P.; McGinty, D.; McGill, S. A.; Smith, R. P.; Reno, J. L.; Turkowski, V.; Perakis, I. E.; Hilton, D. J.; Karaiskaj, D.

    2017-06-01

    We have performed two-dimensional Fourier transform spectroscopy on intrinsic and modulation doped quantum wells in external magnetic fields up to 10 T. In the undoped sample, the strong Coulomb interactions and the increasing separations of the electron and hole charge distributions with increasing magnetic fields lead to a nontrivial in-plane dispersion of the magneto-excitons. Thus, the discrete and degenerate Landau levels are coupled to a continuum. The signature of this continuum is the emergence of elongated spectral line shapes at the Landau level energies, which are exposed by the multidimensional nature of our technique. Surprisingly, the elongation of the peaks is completely absent in the lowest Landau level spectra obtained from the modulation doped quantum well at high fields.

  6. Surface transfer doping induced effective modulation on ambipolar characteristics of few-layer black phosphorus

    Science.gov (United States)

    Xiang, Du; Han, Cheng; Wu, Jing; Zhong, Shu; Liu, Yiyang; Lin, Jiadan; Zhang, Xue-Ao; Ping Hu, Wen; Özyilmaz, Barbaros; Neto, A. H. Castro; Wee, Andrew Thye Shen; Chen, Wei

    2015-03-01

    Black phosphorus, a fast emerging two-dimensional material, has been configured as field effect transistors, showing a hole-transport-dominated ambipolar characteristic. Here we report an effective modulation on ambipolar characteristics of few-layer black phosphorus transistors through in situ surface functionalization with caesium carbonate (Cs2CO3) and molybdenum trioxide (MoO3), respectively. Cs2CO3 is found to strongly electron dope black phosphorus. The electron mobility of black phosphorus is significantly enhanced to ~27 cm2 V-1 s-1 after 10 nm Cs2CO3 modification, indicating a greatly improved electron-transport behaviour. In contrast, MoO3 decoration demonstrates a giant hole-doping effect. In situ photoelectron spectroscopy characterization reveals significant surface charge transfer occurring at the dopants/black phosphorus interfaces. Moreover, the surface-doped black phosphorus devices exhibit a largely enhanced photodetection behaviour. Our findings coupled with the tunable nature of the surface transfer doping scheme ensure black phosphorus as a promising candidate for further complementary logic electronics.

  7. 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 that the ...

  8. Laser direct writing of modulation-doped nanowire p/n junctions

    Science.gov (United States)

    Nam, Woongsik; Mitchell, James I.; Xu, Xianfan

    2016-12-01

    We demonstrate a single-step, laser-based technique to fabricate axial modulation-doped silicon nanowires. Our method is based on laser-direct-write chemical vapor deposition and has the capability to fabricate nanowires as small as 60 nm, which is far below the diffraction limit of the laser wavelength of 395 nm, with precise control of nanowire position, length, and orientation. By switching dopant gases during nanowire writing, p-n junction nanowires are produced. The p-n junction nanowires are fabricated into multifinger devices with parallel metal contacts and electrically tested to demonstrate diode characteristics.

  9. Complex dynamical behaviors in modulation-doped GaAs/AlxGa1-x As heterostructures

    Institute of Scientific and Technical Information of China (English)

    李国辉; 周世平; 徐得名

    2001-01-01

    We study dynamics of the forced modulation-doped GaAs/AIGaAs heterostructure devices. The coupled differential equations governing the dynamical behaviors are numerically simulated.Biased with an appropriate dc field, the system exhibits two states: spontaneous current oscillation and fixed points. By imposing an ac driving force, the dynamical system shows frequency locking,quasiperiodicity, and chaos, which are sensitive to the amplitude and frequency of the externally applied periodical microwave field. The basins of attraction of both ordinary attractors and strange attractors are presented.

  10. Integrated silicon p–i–n structures with highly doped p++, n++ regions for modulation in terahertz frequency band

    OpenAIRE

    2010-01-01

    Modulators of terahertz range on the base of silicon integrated p–i–n-structures are investigated theoretically. The generalization of the Fletcher boundary conditions at the injecting contacts has been put forward for the case of highly doped p++, n++ regions, where both forbidden gap narrowing and dependence of coefficients of diffusion on doping concentration are taken into account. The problem of double injection into i-region has been simulated in a two-dimensional case. The investigatio...

  11. Improved two-dimensional electron mobility in asymmetric barrier delta-doped GaAs/AlGaAs modulation-doped field-effect transistor structures

    Science.gov (United States)

    Das, Sudhakar; Mohapatra, Meryleen; Nayak, Rasmita K.; Panda, Ajit K.; Sahu, Trinath

    2017-03-01

    We study the enhancement of electron mobility μ in barrier delta-doped GaAs/AlGaAs quantum-well-based modulation-doped field-effect transistor (MODFET) structures. We asymmetrically vary the doping concentrations N d1 and N d2 in the barriers on the substrate and surface sides, respectively, to obtain a nonlinear enhancement of μ as a function of the well width w through multi-subband effects. We show that an increase in doping concentration increases the surface electron density N s, which in turn enhances μ. Interchanging N d1 and N d2 leads to no change in N s but rather, an enhancement of μ as a function of w for N d2 > N d1 owing to asymmetric variation of subband wave functions, thereby implying a higher channel conductivity in a surface-doped structure than in an inverted doped structure. By keeping (N d1 + N d2) unchanged, the conductivity of a single-channel MODFET, N d1 (N d2) ≠ 0 and N d2 (N d1) = 0, can be enhanced by considering a MODFET based on an asymmetrically doped (N d1 ≠ N d2 ≠ 0) quantum well structure. We show that the highest N s and μ product for these structures occurs almost before the onset of the occupation of the second subband. Our analysis of the effect of asymmetric doping profiles on channel conductivity can be utilized for the performance improvement of MODFET-like devices.

  12. Effect of Sr-doping of LaMnO3 spacer on modulation-doped two-dimensional electron gases at oxide interfaces

    Science.gov (United States)

    Chen, Y. Z.; Gan, Y. L.; Christensen, D. V.; Zhang, Y.; Pryds, N.

    2017-03-01

    Modulation-doped oxide two-dimensional electron gas formed at the LaMnO3 (LMO) buffered disorderd-LaAlO3/SrTiO3 (d-LAO/LMO/STO) heterointerface provides new opportunities for electronics as well as quantum physics. Herein, we studied the dependence of Sr-doping of La1-xSrxMnO3 (LSMO, x = 0, 1/8, 1/3, ½, and 1) spacer on the transport properties of d-LAO/LSMO/STO in order to determine the effects of the filling of Mn eg subbands as well as the LSMO polarity on the modulation-doping. Upon increasing the LSMO film thickness from 1 unit cell (uc) to 2 uc, a sharp metal to insulator transition of interface conduction was observed, independent of x. The resultant electron mobility is higher than 1900 cm2 V-1 s-1 at 2 K, which increases upon decreasing x. The sheet carrier density, on the other hand, is in the range of 6.9 × 1012˜1.8 × 1013 cm-2 (0.01 ˜ 0.03 e/uc) and is largely independent on x for all the metallic d-LAO/LSMO (1 uc)/STO interfaces. These results are consistent with the charge transfer induced modulation doping scheme and clarify that the polarity of the buffer layer plays a trivial role on the modulation doping. The negligible tunability of the carrier density could result from the reduction of LSMO during the deposition of disordered LAO or that the energy levels of Mn 3d electrons at the interface of LSMO/STO are hardly varied even when changing the LSMO composition from LMO to SrMnO3.

  13. Metalorganic chemical vapor phase epitaxy of narrow-band distributed Bragg reflectors realized by GaN:Ge modulation doping

    Science.gov (United States)

    Berger, Christoph; Lesnik, Andreas; Zettler, Thomas; Schmidt, Gordon; Veit, Peter; Dadgar, Armin; Bläsing, Jürgen; Christen, Jürgen; Strittmatter, André

    2016-04-01

    We report on metalorganic vapor phase epitaxy (MOVPE) of distributed Bragg reflectors (DBR) applying a periodic modulation of the GaN doping concentration only. The doping modulation changes the refractive index of GaN via the Burstein-Moss-effect. MOVPE growth of highly doped GaN:Ge and modulation of the dopant concentration by at least two orders of magnitude within few nanometers is required to achieve a refractive index contrast of 2-3%. Such modulation characteristic is achieved despite the presence of Ge memory effects and incorporation delay. We realized DBRs with up to 100 layer pairs by combining GaN:Ge with a nominal doping concentration of 1.6×1020 cm-3 as low-refractive index material with unintentionally doped GaN as high-refractive index layer. Scanning transmission electron microscope images reveal DBR structures with abrupt interfaces and homogenous layer thicknesses in lateral and vertical direction. Reflectance measurements of DBRs designed for the blue and near UV-spectral region show a narrow stopband with a maximum reflectivity of 85% at 418 nm and even 95% at 370 nm. InGaN/GaN multi-quantum well structures grown on top of such DBRs exhibit narrow emission spectra with linewidths below 3 nm and significantly increased emission intensity.

  14. High-temperature segmented thermoelectric oxide module using p-type Ca3Co4O9 and n-type ZnAlO/CaMn0.95Nb0.05O3 legs

    DEFF Research Database (Denmark)

    Le, Thanh Hung; Van Nong, Ngo; Jeffrey Snyder, G.;

    temperatures up to 1200 K, where most the conventional TE materials based on alloys are often degraded over the time. In this report, oxide TE materials of p­type Ca3Co4O9, n­types ZnAlO, and CaMn0.95Nb0.05O3 were used to fabricate high temperature TE segmented modules. These oxide materials were prepared....... In these calculations, the power generation characteristics were investigated in terms of various n-­leg selections (ZnAlO, CaMn0.95Nb0.05O3, and segmented ZnAlO/CaMn0.95Nb0.05O3), while the p-leg Ca3Co4O9 was fixed. Based on the model predication, several modules were fabricated, tested, and compared again...

  15. A structurally-controllable spin filter in a δ-doped magnetically modulated semiconductor nanostructure with zero average magnetic field

    Science.gov (United States)

    Shen, Li-Hua; Ma, Wen-Yue; Zhang, Gui-Lian; Yang, Shi-Peng

    2015-07-01

    We report on a theoretical investigation of spin-polarized transport in a δ-doped magnetically modulated semiconductor nanostructure, which can be experimentally realized by depositing a ferromagnetic stripe on the top of a semiconductor heterostructure and by using the atomic layer doping technique such as molecular beam epitaxy (MBE). It is shown that although such a nanostructure has a zero average magnetic filed, a sizable spin polarization exists due to the Zeeman splitting mechanism. It is also shown that the degree of spin polarization varies sensitively with the weight and/or position of the δ-doping. Therefore, one can conveniently tailor the behaviour of the spin-polarized electron by tuning the δ -doping, and such a device can be employed as a controllable spin filter for spintronics.

  16. An Electro-Optic Modulator Based on GeO2-Doped Silica Ridge Waveguides with Thermal Poling

    Institute of Scientific and Technical Information of China (English)

    曹霞; 何赛灵

    2003-01-01

    A Mach-Zehnder electro-optic modulator is designed and fabricated based on upper-clad GeO2-doped silica ridge waveguides with thermal poling. The electro-optic coefficient obtained is about 0.05 pm/V and is polarizationinsensitive. An extinction ratio of over 17dB is achieved. The transmission loss of the modulator for the TE mode is 2-3 dB higher than that for the TM mode after the poling.

  17. 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.

  18. 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.

  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. Gibbs–Thomson Effect in Planar Nanowires: Orientation and Doping Modulated Growth

    KAUST Repository

    Shen, Youde

    2016-06-02

    Epitaxy-enabled bottom-up synthesis of self-assembled planar nanowires via the vapor-liquid-solid mechanism is an emerging and promising approach toward large-scale direct integration of nanowire-based devices without postgrowth alignment. Here, by examining large assemblies of indium tin oxide nanowires on yttria-stabilized zirconia substrate, we demonstrate for the first time that the growth dynamics of planar nanowires follows a modified version of the Gibbs-Thomson mechanism, which has been known for the past decades to govern the correlations between thermodynamic supersaturation, growth speed, and nanowire morphology. Furthermore, the substrate orientation strongly influences the growth characteristics of epitaxial planar nanowires as opposed to impact at only the initial nucleation stage in the growth of vertical nanowires. The rich nanowire morphology can be described by a surface-energy-dependent growth model within the Gibbs-Thomson framework, which is further modulated by the tin doping concentration. Our experiments also reveal that the cutoff nanowire diameter depends on the substrate orientation and decreases with increasing tin doping concentration. These results enable a deeper understanding and control over the growth of planar nanowires, and the insights will help advance the fabrication of self-assembled nanowire devices. © 2016 American Chemical Society.

  1. Mobility modulation in inverted delta doped coupled double quantum well structure

    Science.gov (United States)

    Sahoo, N.; Sahu, T.

    2016-10-01

    We have studied the modulation of electron mobility μ as a function of the electric field perpendicular to the interface plane Fp in a GaAs/AlGaAs double quantum well structure near the resonance of subband states. The functional dependence of μ on Fp exhibits a minimum near the anticrossing of subband states leading to an oscillatory behavior of μ. We show that the oscillatory enhancement of μ becomes more pronounced with increase in the difference between the doping concentrations in the side barriers. The oscillation of μ also increases by varying the widths of the two wells through shifting of the position of the middle barrier. It is interesting to show that the oscillation of μ is always larger when there is doping in barrier towards the substrate side compared to that of the surface side due to the difference in the influence of the interface roughness scattering potential. Further, broadening of the central barrier width increases the peaks of the oscillation of μ mostly due to the changes in the ionized impurity scattering potential. Our results can be utilized for the performance enhancement of quantum well field effect transistor devices.

  2. Mobility modulation in inverted delta doped coupled double quantum well structure

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, N. [Department of Electronic Science, Berhampur University, 760007, Odisha (India); Sahu, T., E-mail: tsahu_bu@rediffmail.com [Department of Electronics and Communication Engineering, National Institute of Science and Technology, Palur Hills, Berhampur 761008, Odisha (India)

    2016-10-01

    We have studied the modulation of electron mobility μ as a function of the electric field perpendicular to the interface plane F{sub p} in a GaAs/AlGaAs double quantum well structure near the resonance of subband states. The functional dependence of μ on F{sub p} exhibits a minimum near the anticrossing of subband states leading to an oscillatory behavior of μ. We show that the oscillatory enhancement of μ becomes more pronounced with increase in the difference between the doping concentrations in the side barriers. The oscillation of μ also increases by varying the widths of the two wells through shifting of the position of the middle barrier. It is interesting to show that the oscillation of μ is always larger when there is doping in barrier towards the substrate side compared to that of the surface side due to the difference in the influence of the interface roughness scattering potential. Further, broadening of the central barrier width increases the peaks of the oscillation of μ mostly due to the changes in the ionized impurity scattering potential. Our results can be utilized for the performance enhancement of quantum well field effect transistor devices.

  3. 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.

  4. Spatial self-phase modulation in the H2TPP(OH)4 doped in Boric Acid Glass

    CERN Document Server

    Allam, Srinivasa Rao; Venkatramaiah, N; Venkatesan, R; Sharan, Alok

    2015-01-01

    Self-diffraction rings or spatial self-phase modulation (SSPM) was observed in tetra-phenyl porphyrin derivative 5,10,15,20 - meso-tetrakis (4-hydroxyphenyl) porphyrin (H2TPP(OH)4) doped in boric acid glass (BAG) at 671 nm excitation wave-length lying within the absorption band of sample with TEM00 mode profile. Intensity modulated Z-scan was performed on these systems to study the thermal diffusion and to estimate the thermo-optic coefficients. The results obtained from self-diffraction rings experiment and modulated Z-scan are compared and analyzed for different concentration.

  5. Analytical treatment for the study of an erbium-doped fiber ring laser fed by a sinusoidally modulated pump power

    Science.gov (United States)

    Sola, I. J.; Martín, J. C.; Álvarez, J. M.

    2006-02-01

    An analytical procedure is employed to account for the response of an erbium-doped fiber ring laser whose pump power is sinusoidally modulated. The approximations considered, only strictly valid for very low modulation indexes (of the order of some hundredths), reveal the origin of some relationships between resonances of the main harmonics present in the laser response. However, both experimental and numerical results show how qualitative conclusions concerning relationships between harmonics are also valid for modulation indexes much higher than the ones corresponding to the approximation validity range.

  6. Weakly doped InP layers prepared by liquid phase epitaxy using a modulated cooling rate

    Science.gov (United States)

    Krukovskyi, R.; Mykhashchuk, Y.; Kost, Y.; Krukovskyi, S.; Saldan, I.

    2017-04-01

    Epitaxial structures based on InP are widely used to manufacture a number of devices such as microwave transistors, light-emitting diodes, lasers and Gunn diodes. However, their temporary instability caused by heterogeneity of resistivity along the layer thickness and the influence of various external or internal factors prompts the need for the development of a new reliable technology for their preparation. Weak doping by Yb, Al and Sn together with modulation of the cooling rate applied to prepare InP epitaxial layers is suggested to be adopted within the liquid phase epitaxy (LPE) method. The experimental results confirm the optimized conditions created to get a uniform electron concentration in the active n-InP layer. A sharp profile of electron concentration in the n+-InP(substrate)/n-InP/n+-InP epitaxial structure was observed experimentally at the proposed modulated cooling rate of 0.3 °С-1.5 °С min-1. The proposed technological method can be used to control the electrical and physical properties of InP epitaxial layers to be used in Gunn diodes.

  7. Effect of Sr-doping of LaMnO3 spacer on modulation-doped two-dimensional electron gases at oxide interfaces

    DEFF Research Database (Denmark)

    Chen, Yunzhong; Gan, Yulin; Christensen, Dennis Valbjørn

    2017-01-01

    Modulation-doped oxide two-dimensional electron gas formed at the LaMnO3 (LMO) buffered disorderd-LaAlO3/SrTiO3 (d-LAO/LMO/STO) heterointerface provides new opportunities for electronics as well as quantum physics. Herein, we studied the dependence of Sr-doping of La1-xSrxMnO3 (LSMO, x = 0, 1/8, ...... of LSMO during the deposition of disordered LAO or that the energy levels of Mn 3d electrons at the interface of LSMO/STO are hardly varied even when changing the LSMO composition from LMO to SrMnO3....

  8. Chirp-free direct modulation of 550 nm emission in Er3+ -Doped Fluoroindate glass by nonlinear feedback control

    Science.gov (United States)

    Cai, Runyu; Thitsa, Makhin; Bluiett, Althea; Brown, Ei; Hommerich, Uwe

    2017-06-01

    We propose a direct modulation method with nonlinear feedback controller which can produce chirp-free modulation of the output pulse without bulky external modulators. This work reports the design of the controller which, via a feedback loop, varies and controls the pump rate in real time by automatically adjusting the pump power to precisely modulate the emission of 550 nm in Er3+ -doped Fluoroindate glass under 1.48 μm pumping. In this interdisciplinary paper, well established theoretical tools from nonlinear control theory are applied to the dynamical system of the laser material in order to produce the desired output of the laser. The controller is simulated in MATLAB Simulink and the simulation results show that our technique yields precise modulation of the output intensity without frequency chirping. Results on both theoretical analysis of the control methodology and simulation are presented.

  9. Spatial modulation spectroscopy for imaging and quantitative analysis of single dye-doped organic nanoparticles inside cells

    Science.gov (United States)

    Devadas, Mary Sajini; Devkota, Tuphan; Guha, Samit; Shaw, Scott K.; Smith, Bradley D.; Hartland, Gregory V.

    2015-05-01

    Imaging of non-fluorescent nanoparticles in complex biological environments, such as the cell cytosol, is a challenging problem. For metal nanoparticles, Rayleigh scattering methods can be used, but for organic nanoparticles, such as dye-doped polymer beads or lipid nanoparticles, light scattering does not provide good contrast. In this paper, spatial modulation spectroscopy (SMS) is used to image single organic nanoparticles doped with non-fluorescent, near-IR croconaine dye. SMS is a quantitative imaging technique that yields the absolute extinction cross-section of the nanoparticles, which can be used to determine the number of dye molecules per particle. SMS images were recorded for particles within EMT-6 breast cancer cells. The measurements allowed mapping of the nanoparticle location and the amount of dye in a single cell. The results demonstrate how SMS can facilitate efforts to optimize dye-doped nanoparticles for effective photothermal therapy of cancer.Imaging of non-fluorescent nanoparticles in complex biological environments, such as the cell cytosol, is a challenging problem. For metal nanoparticles, Rayleigh scattering methods can be used, but for organic nanoparticles, such as dye-doped polymer beads or lipid nanoparticles, light scattering does not provide good contrast. In this paper, spatial modulation spectroscopy (SMS) is used to image single organic nanoparticles doped with non-fluorescent, near-IR croconaine dye. SMS is a quantitative imaging technique that yields the absolute extinction cross-section of the nanoparticles, which can be used to determine the number of dye molecules per particle. SMS images were recorded for particles within EMT-6 breast cancer cells. The measurements allowed mapping of the nanoparticle location and the amount of dye in a single cell. The results demonstrate how SMS can facilitate efforts to optimize dye-doped nanoparticles for effective photothermal therapy of cancer. Electronic supplementary information (ESI

  10. Doping Scheme of Semiconducting Atomic Chains

    Science.gov (United States)

    Toshishige, Yamada; Saini, Subhash (Technical Monitor)

    1998-01-01

    Atomic chains, precise structures of atomic scale created on an atomically regulated substrate surface, are candidates for future electronics. A doping scheme for intrinsic semiconducting Mg chains is considered. In order to suppress the unwanted Anderson localization and minimize the deformation of the original band shape, atomic modulation doping is considered, which is to place dopant atoms beside the chain periodically. Group I atoms are donors, and group VI or VII atoms are acceptors. As long as the lattice constant is long so that the s-p band crossing has not occurred, whether dopant atoms behave as donors or acceptors is closely related to the energy level alignment of isolated atomic levels. Band structures are calculated for Br-doped (p-type) and Cs-doped (n-type) Mg chains using the tight-binding theory with universal parameters, and it is shown that the band deformation is minimized and only the Fermi energy position is modified.

  11. 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.

  12. Nonlinear response of a unidirectional erbium-doped fiber ring laser to a sinusoidally modulated pump power

    Science.gov (United States)

    Sola, I. J.; Martín, J. C.; Álvarez, J. M.

    2002-11-01

    The response of a unidirectional erbium-doped fiber ring laser, excited by a sinusoidally modulated pump power, is analyzed both experimentally and theoretically. Experimentally, several resonance peaks are observed, as well as different frequency ranges showing bistable behaviour. Appearance of all resonance peaks obtained can be explained taking into account simple relations between the pump modulation frequency and the system natural frequency. Theoretically, it is shown how a model which combines the theory of erbium-doped fibers and the semiclassical laser treatment can account for all phenomena observed, with good agreement. In particular, it is demonstrated that a correct description of the bistable regions requires taking into account powers and population distributions along the laser active medium.

  13. Transparent conductivity modulation of ZnO by group-IVA doping

    Science.gov (United States)

    Liu, J.; Fan, X. F.; Sun, C. Q.; Zhu, W.

    2016-04-01

    We examined the effect of group-IVA doping on the electronic structure and transmittance of ZnO using first-principle calculations. All these doped ZnO materials are found to perform n-type conductive behavior. Si-doped ZnO and Pb-doped ZnO are found to have larger optical band gap than those of Ge-doped ZnO and Sn-doped ZnO. The transmittance of Si-doped ZnO is found to be high in both UV and visible region. The enhancement of UV region transmittance can be attributed to the enhanced optical band gap, while the reduction of visible region transmittance is due to the intraband optical transition.

  14. Characteristics of InAs/AlGaAs self-organized quantum dot modulation doped field effect transistors

    Science.gov (United States)

    Phillips, J.; Kamath, K.; Brock, T.; Bhattacharya, P.

    1998-06-01

    We have investigated the dc characteristics of InGaAs/AlGaAs modulation doped field effect transistors in which a layer of self-organized InAs quantum dots is inserted adjacent to the pseudomorphic quantum well channel. Distinct steps and a negative differential resistance are observed in the current-voltage characteristics at room temperature and lower temperatures. These are attributed to conduction through the bound states in the quantum dots.

  15. High electron mobility of modulation doped GaAs after growing InP by solid source molecular beam epitaxy

    Institute of Scientific and Technical Information of China (English)

    SHU Yong-chun; PI Biao; LIN Yao-wang; XING Xiao-dong; YAO Jiang-hong; WANG Zhan-guo; XU Jing-jun

    2005-01-01

    Modulation-doped AlGaAs/GaAs structures were grown on GaAs(100) substrate by solid source molecular beam epitaxy (SSMBE) system. The factors which influence the electron mobility were investigated. After growing InP based materials, growth conditions were deteriorated, but by an appropriate method and using reasonaand growth conditions have been studied and optimized via Hall measurements. For a typical sample, 2.0 K electron served.

  16. Analysis of the Crosstalk in WDM Systems Caused by Cross-phase Modulation in Erbium-doped Fiber Amplifiers

    Institute of Scientific and Technical Information of China (English)

    LIU Ning; LIAO Changjun; LIU Songhao; GUO Qi; XU Wengchen

    2001-01-01

    The crosstalk in WDM systems caused by cross-phase modulation (XPM) in erbium-doped fiber amplifiers(EDFA) was studied analytically. The results confirm that the EDFA induced phase shift does cause crosstalk in WDM systems. The crosstalk between two channels both with modulated pulse signals is studied for the first time. It was found that the EDFA induced phase shift will cause serious deterioration of the eye diagram when the optical signals continue to travel in the normal-dispersion regime of the transmission fiber, while in the anomalous-dispersion regime this phase shift will not cause much deterioration of the eye diagram.

  17. Pulsed ytterbium-doped fibre laser with a combined modulator based on single-wall carbon nanotubes

    Science.gov (United States)

    Khudyakov, D. V.; Borodkin, A. A.; Lobach, A. S.; Vartapetov, S. K.

    2015-09-01

    This paper describes an all-normal-dispersion pulsed ytterbium-doped fibre ring laser mode-locked by a nonlinear combined modulator based on single-wall carbon nanotubes. We have demonstrated 1.7-ps pulse generation at 1.04 μm with a repetition rate of 35.6 MHz. At the laser output, the pulses were compressed to 180 fs. We have examined an intracavity nonlinear modulator which utilises nonlinear polarisation ellipse rotation in conjunction with a saturable absorber in the form of a polymer-matrix composite film containing single-wall carbon nanotubes.

  18. Pulsed ytterbium-doped fibre laser with a combined modulator based on single-wall carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Khudyakov, D V; Borodkin, A A; Vartapetov, S K [Physics Instrumentation Center, A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Troitsk, Moscow Region (Russian Federation); Lobach, A S [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region (Russian Federation)

    2015-09-30

    This paper describes an all-normal-dispersion pulsed ytterbium-doped fibre ring laser mode-locked by a nonlinear combined modulator based on single-wall carbon nanotubes. We have demonstrated 1.7-ps pulse generation at 1.04 μm with a repetition rate of 35.6 MHz. At the laser output, the pulses were compressed to 180 fs. We have examined an intracavity nonlinear modulator which utilises nonlinear polarisation ellipse rotation in conjunction with a saturable absorber in the form of a polymer-matrix composite film containing single-wall carbon nanotubes. (lasers)

  19. Dynamics of an erbium-doped fiber laser subjected to harmonic modulation of a diode pump laser

    Science.gov (United States)

    Pisarchik, Alexander N.; Kir'yanov, Alexander V.; Barmenkov, Yuri O.; Reategui, R. J.

    2004-10-01

    An erbium-doped fiber laser is shown to operate as a bistable or multistable nonlinear system under harmonic modulation of the diode pump laser. Phase- and frequency-dependent states are demonstrated both experimentally and in numerical simulations through codimensional-one and codimensional-two bifurcation diagrams in the parameter space of the modulation frequency and amplitude. In particular, generalized bistability results in doubling of saddle-node bifurcation lines where different coexisting attractors born. The laser model describes well all experimental features.

  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. Controllable GMR device in a δ-doped, magnetically and electrically modulated, GaAs /Alx Ga1-x As heterostructure

    Science.gov (United States)

    Shen, Li-Hua; Zhang, Gui-Lian; Yang, Duan-Chui

    2016-09-01

    We report on a theoretical study of giant magnetoresistance (GMR) effect in a δ-doped GaAs /Alx Ga1-x As heterostructure modulated by two stripes of ferromagnetic metal and a stripe of Schottky metal in parallel configuration. The δ-doping dependent transmission and conductance of the device are calculated. It is shown that a considerable giant magnetoresistance (GMR) effect exists in this structure. It is also shown that the magnetoresistance ratio (MR) can be switched by the δ-doping. The underlying physical mechanism of the results is analysed in light of δ-doping-dependent tunneling process in the device.

  2. Mass spectrometric characterization of the selective androgen receptor modulator (SARM) YK-11 for doping control purposes.

    Science.gov (United States)

    Thevis, Mario; Piper, Thomas; Dib, Josef; Lagojda, Andreas; Kühne, Dirk; Packschies, Lars; Geyer, Hans; Schänzer, Wilhelm

    2017-07-30

    Selective androgen receptor modulators (SARMs) represent an emerging class of therapeutics targeting inter alia conditions referred to as cachexia and sarcopenia. Due to their anabolic properties, the use of SARMs is prohibited in sports as regulated by the World Anti-Doping Agency (WADA), and doping control laboratories test for these anabolic agents in blood and urine. In order to accomplish and maintain comprehensive test methods, the characterization of new drug candidates is critical for efficient sports drug testing. Hence, in the present study the mass spectrometric properties of the SARM YK-11 were investigated. YK-11 was synthesized according to literature data and three different stable-isotope-labeled analogs were prepared to support the mass spectrometric studies. Using high-resolution/high-accuracy mass spectrometry following electrospray ionization as well as electron ionization, the dissociation pathways of YK-11 were investigated, and characteristic features of its (product ion) mass spectra were elucidated. These studies were flanked by density functional theory (DFT) computation providing information on proton affinities of selected functional groups of the analyte. The steroidal SARM YK-11 was found to readily protonate under ESI conditions followed by substantial in-source dissociation processes eliminating methanol, acetic acid methyl ester, and/or ketene. DFT computation yielded energetically favored structures of the protonated species resulting from the aforementioned elimination processes particularly following protonation of the steroidal D-ring substituent. Underlying dissociation pathways were suggested, supported by stable-isotope labeling of the analyte, and diagnostic product ions for the steroidal nucleus and the D-ring substituent were identified. Further, trimethylsilylated YK-11 and its deuterated analogs were subjected to electron ionization high-resolution/high-accuracy mass spectrometry, complementing the dataset characterizing

  3. Nanoscale imaging of freestanding nitrogen doped single layer graphene.

    Science.gov (United States)

    Iyer, Ganjigunte R S; Wang, Jian; Wells, Garth; Bradley, Michael P; Borondics, Ferenc

    2015-02-14

    Graphene can be p-type or n-type doped by introduction of specific species. Doping can modulate the electronic properties of graphene, but opening a sizable-well-tuned bandgap is essential for graphene-based tunable electronic devices. N-doped graphene is widely used for device applications and is mostly achieved by introducing ammonia into the synthesis gas during the chemical vapor deposition (CVD) process. Post synthesis treatment studies to fine-tune the electron hole doping in graphene are limited. In this work realization of N-doping in large area freestanding single layer graphene (LFG) is achieved by post treatment in nitrogen plasma. The changes in the chemical and electronic properties of graphene are followed with Raman microscopy and mapped via synchrotron based scanning transmission X-ray microscopy (STXM) at the nanoscale.

  4. Nanoscale imaging of freestanding nitrogen doped single layer graphene

    Science.gov (United States)

    Iyer, Ganjigunte R. S.; Wang, Jian; Wells, Garth; Bradley, Michael P.; Borondics, Ferenc

    2015-01-01

    Graphene can be p-type or n-type doped by introduction of specific species. Doping can modulate the electronic properties of graphene, but opening a sizable-well-tuned bandgap is essential for graphene-based tunable electronic devices. N-doped graphene is widely used for device applications and is mostly achieved by introducing ammonia into the synthesis gas during the chemical vapor deposition (CVD) process. Post synthesis treatment studies to fine-tune the electron hole doping in graphene are limited. In this work realization of N-doping in large area freestanding single layer graphene (LFG) is achieved by post treatment in nitrogen plasma. The changes in the chemical and electronic properties of graphene are followed with Raman microscopy and mapped via synchrotron based scanning transmission X-ray microscopy (STXM) at the nanoscale.Graphene can be p-type or n-type doped by introduction of specific species. Doping can modulate the electronic properties of graphene, but opening a sizable-well-tuned bandgap is essential for graphene-based tunable electronic devices. N-doped graphene is widely used for device applications and is mostly achieved by introducing ammonia into the synthesis gas during the chemical vapor deposition (CVD) process. Post synthesis treatment studies to fine-tune the electron hole doping in graphene are limited. In this work realization of N-doping in large area freestanding single layer graphene (LFG) is achieved by post treatment in nitrogen plasma. The changes in the chemical and electronic properties of graphene are followed with Raman microscopy and mapped via synchrotron based scanning transmission X-ray microscopy (STXM) at the nanoscale. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05385k

  5. Electrical spin injection in modulation-doped GaAs from an in situ grown Fe/MgO layer

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Seong Hoon [Center for Spintronics, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Department of Physics, Korea University, Seoul 136-713 (Korea, Republic of); Kim, Hyung-jun [Center for Spintronics, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Koo, Hyun Cheol [Center for Spintronics, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-701 (Korea, Republic of); Lee, Yun-Hi [Department of Physics, Korea University, Seoul 136-713 (Korea, Republic of); Chang, Joonyeon, E-mail: presto@kist.re.kr [Center for Spintronics, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Department of Nanomaterials Science and Engineering, Korea University of Science and Technology, Daejeon 305-350 (Korea, Republic of)

    2015-09-07

    We study spin accumulation in n-doped GaAs that were electrically injected from Fe via MgO using three-terminal Hanle measurement. The Fe/MgO/GaAs structures were prepared in a cluster molecular beam epitaxy that did not require the breaking of the vacuum. We found the crystal orientation relationship of epitaxial structures Fe[100]//MgO[110]//GaAs[110] without evident defects at the interface. Control of depletion width and interface resistance by means of modulation doping improves spin injection, leading to enhanced spin voltage (ΔV) of 6.3 mV at 10 K and 0.8 mV even at 400 K. The extracted spin lifetime and spin diffusion length of GaAs are 220 ps and 0.77 μm, respectively, at 200 K. MgO tunnel barrier grown in situ with modulation doping at the interface appears to be promising for spin injection into GaAs.

  6. 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.

  7. Spin transport in p-type germanium.

    Science.gov (United States)

    Rortais, F; Oyarzún, S; Bottegoni, F; Rojas-Sánchez, J-C; Laczkowski, P; Ferrari, A; Vergnaud, C; Ducruet, C; Beigné, C; Reyren, N; Marty, A; Attané, J-P; Vila, L; Gambarelli, S; Widiez, J; Ciccacci, F; Jaffrès, H; George, J-M; Jamet, M

    2016-04-27

    We report on the spin transport properties in p-doped germanium (Ge-p) using low temperature magnetoresistance measurements, electrical spin injection from a ferromagnetic metal and the spin pumping-inverse spin Hall effect method. Electrical spin injection is carried out using three-terminal measurements and the Hanle effect. In the 2-20 K temperature range, weak antilocalization and the Hanle effect provide the same spin lifetime in the germanium valence band (≈1 ps) in agreement with predicted values and previous optical measurements. These results, combined with dynamical spin injection by spin pumping and the inverse spin Hall effect, demonstrate successful spin accumulation in Ge. We also estimate the spin Hall angle θ(SHE) in Ge-p (6-7 x 10(-4) at room temperature, pointing out the essential role of ionized impurities in spin dependent scattering.

  8. Ferromagnetism modulation by phase change in Mn-doped GeTe chalcogenide magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Adam, Adam Abdalla Elbashir [Huazhong University of Science and Technology, School of Optical and Electronic Information, Wuhan (China); Wuhan National Laboratory for Optoelectronics, Wuhan (China); Alneelain University, Faculty of Science and Technology, Khartoum (Sudan); Cheng, Xiaomin; Guan, Xiawei; Miao, Xiangshui [Huazhong University of Science and Technology, School of Optical and Electronic Information, Wuhan (China); Wuhan National Laboratory for Optoelectronics, Wuhan (China)

    2014-12-15

    In this work, an effective method to modulate the ferromagnetic properties of Mn-doped GeTe chalcogenide-based phase change materials is presented. The microstructure of the phase change magnetic material Ge{sub 1-x} Mn{sub x} Te thin films was studied. The X-ray diffraction results demonstrate that the as-deposited films are amorphous, and the crystalline films are formed after annealing at 350 C for 10 min. Crystallographic structure investigation shows the existence of some secondary magnetic phases. The lattice parameters of Ge{sub 1-x} Mn{sub x} Te (x = 0.04, 0.12 and 0.15) thin films are found to be slightly different with changes of Mn compositions. The structural analysis clearly indicates that all the films have a stable rhombohedral face-centered cubic polycrystalline structure. The magnetic properties of the amorphous and crystalline Ge{sub 0.96}Mn{sub 0.04}Te were investigated. The measurements of magnetization (M) as a function of the magnetic field (H) show that both amorphous and crystalline phases of Ge{sub 0.96}Mn{sub 0.04}Te thin film are ferromagnetic and there is drastic variation between amorphous and crystalline states. The temperature (T) dependence of magnetizations at zero field cooling (ZFC) and field cooling (FC) conditions of the crystalline Ge{sub 0.96}Mn{sub 0.04}Te thin film under different applied magnetic fields were performed. The measured data at 100 and 300 Oe applied magnetic fields show large bifurcations in the ZFC and FC curves while on the 5,000 Oe magnetic field there is no deviation. (orig.)

  9. Linear and nonlinear resonance features of an erbium-doped fibre ring laser under cavity-loss modulation

    Indian Academy of Sciences (India)

    Aditi Ghosh; R Vijaya

    2014-07-01

    The continuous-wave output of a single-mode erbium-doped fibre ring laser when subjected to cavity-loss modulation is found to exhibit linear as well as nonlinear resonances. At sufficiently low driving amplitude, the system resembles a linear damped oscillator. At higher amplitudes, the dynamical study of these resonances shows that the behaviour of the system exhibits features of a nonlinear damped oscillator under harmonic modulation. These nonlinear dynamical features, including harmonic and subharmonic resonances, have been studied experimentally and analysed with the help of a simple time-domain and frequency-domain information obtained from the output of the laser. All the studies are restricted to the modulation frequency lying in a regime near the relaxation oscillation frequency.

  10. Fabrication of p-type ZnO nanofibers by electrospinning for field-effect and rectifying devices

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shuai; Liu, Shu-Liang; Liu, Ling-Zhi; Liu, Yi-Chen [College of Physics, Qingdao University, Qingdao 266071 (China); Long, Yun-Ze, E-mail: yunze.long@163.com [College of Physics, Qingdao University, Qingdao 266071 (China); Key Laboratory of Photonics Materials and Technology in Universities of Shandong (Qingdao University), Qingdao 266071 (China); State Key Laboratory Cultivation Base of New Fiber Materials and Modern Textile, Qingdao University, Qingdao 266071 (China); Collaborative Innovation Center for Marine Biomass Fibers, Materials and Textiles of Shandong Province, Qingdao 266071 (China); Zhang, Hong-Di; Zhang, Jun-Cheng; Han, Wen-Peng [College of Physics, Qingdao University, Qingdao 266071 (China); Key Laboratory of Photonics Materials and Technology in Universities of Shandong (Qingdao University), Qingdao 266071 (China)

    2014-01-27

    Ce-doped p-type ZnO nanofibers were synthesized by electrospinning and followed calcinations. The surface morphology, elementary composition, and crystal structure of the nanofibers were investigated. The field effect curve confirms that the resultant Ce-doped ZnO nanofibers are p-type semiconductor. A p-n heterojunction device consisting of Ce-doped p-type ZnO nanofibers and n-type indium tin oxide (ITO) thin film was fabricated on a piece of quartz substrate. The current-voltage (I-V) characteristic of the p-n heterojunction device shows typical rectifying diode behavior. The turn-on voltage appears at about 7 V under the forward bias and the reverse current is impassable.

  11. 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...

  12. An experiment of dynamical behaviours in an erbium-doped fibre-ring laser with loss modulation

    Institute of Scientific and Technical Information of China (English)

    Liu Yue; Feng Xue; Zhang Wei; Liu Xiao-Ming

    2009-01-01

    This paper reports a systematic experimental investigation on the dynamics in the low-frequency region in an erbium-doped fibre-ring laser with loss modulation.A rich variety of bifurcation is analyzed through the bifurcation diagram and structured with the concept of the winding numbers.The coexistence of multiple attractors and the crisis that appear in the saddle-node bifurcations,and an interesting structure of bifurcation which is similar to the bifurcations in high-frequency range,have been observed.

  13. Method for producing high carrier concentration p-Type transparent conducting oxides

    Science.gov (United States)

    Li, Xiaonan; Yan, Yanfa; Coutts, Timothy J.; Gessert, Timothy A.; Dehart, Clay M.

    2009-04-14

    A method for producing transparent p-type conducting oxide films without co-doping plasma enhancement or high temperature comprising: a) introducing a dialkyl metal at ambient temperature and a saturated pressure in a carrier gas into a low pressure deposition chamber, and b) introducing NO alone or with an oxidizer into the chamber under an environment sufficient to produce a metal-rich condition to enable NO decomposition and atomic nitrogen incorporation into the formed transparent metal conducting oxide.

  14. Precipitation of Cu and Ni in n- and p-type Czochralski-grown silicon characterized by photoluminescence imaging

    Science.gov (United States)

    Sun, Chang; Nguyen, Hieu T.; Rougieux, Fiacre E.; Macdonald, Daniel

    2017-02-01

    Photoluminescence (PL) images and micro-PL maps were taken on Cu- or Ni-doped monocrystalline silicon wafers, to investigate the distribution of the metal precipitates. Several n-type and p-type wafers were used in which Cu or Ni were introduced in the starting melt of the ingots and precipitated during the ingot cooling (as opposed to surface contamination). The micro-PL mapping allowed investigation of the metal precipitates with a higher spatial resolution. Markedly different precipitation patterns were observed in n- and p-type samples: in both Cu- and Ni-doped n-type samples, circular central regions and edge regions were observed. In these regions, particles were distributed randomly and homogeneously. In the p-type Cu-doped and Ni-doped samples, by contrast, the precipitates occurred in lines along orientations. The difference in the precipitation behaviour in n- and p-type samples is conjectured to be caused by different concentrations of self-interstitials and vacancies remaining in the crystal during the ingot cooling: there are more vacancies in the n-type ingots but more interstitials in the p-type ingots. The dopant effects on the intrinsic point defect concentrations in silicon crystals and possible precipitation mechanisms are discussed based on the findings in this work and the literature.

  15. Heterodimensional Schottky contacts to modulation-doped heterojunction with application to photodetection

    Science.gov (United States)

    Seddik, Amro Anwar

    The growing technological demand for high speed and compact integrated electronics and Optics is a pressing challenge. Speed and compactness necessitate low power consumption semiconductors with high transport mobility carriers, with potential of ultra large-scale integration of electronic and Optoelectronics circuitry. One avenue to fulfill these requirements is to utilize reduced dimensionality where carriers are spatially confined to less than three-dimensions, causing their energy levels to become quantized and their transport favorably affected. With recent progress in semiconductor growth and processing technologies low dimensionality has become practically realizable, this makes the study of contact properties to these systems increasingly important. In this work we study the contact between a low- dimensional semiconductor structure and a three- dimensional metal and the application of such a contact in photodetection. We theoretically derive the thermionic emission current for Schottky contact to two-dimensional and one-dimensional structures. The derivation underscores the discrete nature of low-dimensional structures and shows that the thermionic emission current is reduced by a factor exponentially proportional to the first quantized energy level. We also propose and formulate, for the first time, a physical phenomenon in two-dimensional structures created by modulation doping of a heterojunction, which is the effect of the cloud of electrons in the small bandgap material on the thermionic emission current. We have named this the electron- electron cloud effect; we show that this interaction increases the effective Schottky barrier height in a fashion counter to the image force lowering mechanism. In order to realize Schottky contact to low-dimensional structures, we have fabricated a novel Heterojunction Metal-Semiconductor-Metal (HMSM) photodetector. Experimental characterization and the general trends of the behavior of the HMSM devices are presented

  16. Investigation of bandgap modulation, field emission and dielectric properties of cadmium doped CaCu3 Ti4O12

    Science.gov (United States)

    Maitra, S.; Mitra, R.; Bera, K. P.; Nath, T. K.

    2017-05-01

    We have prepared cadmium doped CCTO (Ca1-xCdxCu3Ti4O12 where x = 0.01, 0.02, 0.03, 0.04, 0.05) by Molten Salt Synthesis technique. It has exhibited high level of crystallinity and a well defined micrometre sized grains with uniform cubic morphology, as confirmed by a combination of X-ray diffraction and field emission scanning electron microscopy. Thereby we have found the modulation of its semiconducting bandgap as a function of doping from recorded UV-Vis reflectance spectra using Kubelka Munk (KM) method where with increasing Cadmium doping content the bandgap is found to increase. We have also carried out investigation on the field emission properties of CCTO crystals and it has exhibited poor field emission characteristics. Finally, we have investigated the dielectric properties of CCTO as a function of temperature. It has exhibited a giant dielectric property with low loss over a considerable temperature regime (50-300°C) and is found to exhibit Maxwell Wagner type dielectric relaxation.

  17. Linear and nonlinear optical absorption coefficients and refractive index changes in modulation-doped quantum wells: Effects of the magnetic field and hydrostatic pressure

    Energy Technology Data Exchange (ETDEWEB)

    Nazari, M.; Karimi, M.J., E-mail: karimi@sutech.ac.ir; Keshavarz, A.

    2013-11-01

    In this study, the linear, the third-order nonlinear and total optical absorption coefficients and refractive index changes of a modulation-doped GaAs/Al{sub x}Ga{sub 1−x}As quantum well are investigated numerically. In the effective-mass approximation, the electronic structure of modulation-doped quantum well is calculated by solving the Schrödinger and Poisson equations self-consistently. Optical properties are obtained using the compact density matrix approach. The effects of structure parameters, the applied magnetic field and the hydrostatic pressure on the optical properties of the modulation-doped quantum well are studied. Results show that the resonant peaks shift toward the higher (lower) energies with the increase in the magnetic field (pressure). The magnitude of the resonant peaks of the optical properties decreases with the increasing magnetic field or pressure.

  18. Wide bandgap n-type and p-type semiconductor porous junction devices as photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yuan-Pai; Horng, Sheng-Fu [Institute of Electronics Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Chao, Yu-Chiang; Meng, Hsin-Fei [Institute of Physics, National Chiao Tung University, Hsinchu 300, Taiwan (China); Zan, Hsiao-Wen, E-mail: yuchiangchao@gmail.com, E-mail: meng@mail.nctu.edu.tw [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (China)

    2011-10-12

    In junction absorber photovoltaics doped wide bandgap n-type and p-type semiconductors form a porous interpenetrating junction structure with a layer of low bandgap absorber at the interface. The doping concentration is high enough such that the junction depletion width is smaller than the pore size. The highly conductive neutral region then has a dentrite shape with fingers reaching the absorber to effectively collect the photo-carriers swept out by the junction electric field. With doping of 10{sup 19} cm{sup -3} corresponding to a depletion width of 25 nm, pore size of 32 nm, absorber thickness close to exciton diffusion length of 17 nm, absorber bandgap of 1.4 eV and carrier mobility over 10{sup -5} cm{sup 2} V{sup -1} s{sup -1}, numerical calculation shows the power conversion efficiency is as high as 19.4%. It rises to 23% for a triplet exciton absorber.

  19. CuNb3O8: A p-Type Semiconducting Metal Oxide Photoelectrode.

    Science.gov (United States)

    Joshi, Upendra A; Maggard, Paul A

    2012-06-07

    A new p-type CuNb3O8 polycrystalline photoelectrode was investigated and was determined to have indirect and direct bandgap sizes of 1.26 and 1.47 eV, respectively. The p-type polycrystalline film could be prepared on fluorine-doped tin oxide glass and yielded a cathodic photocurrent under visible-light irradiation (λ > 420 nm) with incident photon-to-current efficiencies of up to ∼6-7% and concomitant hydrogen evolution. A Mott-Schottky analysis yielded a flat band potential of +0.35 V versus RHE (pH = 6.3) and a calculated p-type dopant concentration of ∼7.2 × 10(15) cm(-3). The conduction band energies are found to be negative enough for the reduction of water under visible light irradiation. A hole mobility of ∼145 cm(2)/V·s was obtained from J(I)-V(2) measurements using the Mott-Gurney relation, which is ∼50% higher than that typically found for p-type Cu2O. DFT-based electronic structure calculations were used to probe the atomic and structural origins of the band gap transitions and carrier mobility. Thus, a new p-type semiconductor is discovered for potential applications in solar energy conversion.

  20. High speed traveling wave electrooptic intensity modulator with a doped PIN semiconductor junction

    Energy Technology Data Exchange (ETDEWEB)

    Vawter, G.A.; Hietala, V.M.; Wendt, J.R.; Fuchs, B.A.; Hafich, M.; Housel, M.; Armendariz, M.; Sullivan, C.T.

    1996-02-01

    A high-electrooptic-efficiency Mach-Zehnder intensity modulator is demonstrated with a bandwidth exceeding 40 GHZ. The 1 mm-long modulator has a switching voltage comparable to undoped semiconductor designs of much greater length.

  1. Thermal conductivity of carbon doped GeTe thin films in amorphous and crystalline state measured by modulated photo thermal radiometry

    Science.gov (United States)

    Kusiak, Andrzej; Battaglia, Jean-Luc; Noé, Pierre; Sousa, Véronique; Fillot, F.

    2016-09-01

    The thermal conductivity and thermal boundary resistance of GeTe and carbon doped GeTe thin films, designed for phase change memory (PCM) applications, were investigated by modulated photo thermal radiometry. It was found that C doping has no significant effect on the thermal conductivity of these chalcogenides in amorphous state. The thermal boundary resistance between the amorphous films and SiO2 substrate is also not affected by C doping. The films were then crystallized by an annealing at 450°C as confirmed by optical reflectivity analysis. The thermal conductivity of non-doped GeTe significantly increases after crystallization annealing. But, surprisingly the thermal conductivity of the crystallized C doped GeTe was found to be similar from that of the amorphous state and independent of C concentration. As for the amorphous phase, C doping does not affect the thermal boundary resistance between the crystalline GeTe films and SiO2 substrate. This behaviour is discussed thanks to XRD and FTIR analysis. In particular, XRD shows a decrease of crystalline grain size in crystalline films as C concentration is increased. FTIR analysis of the film before and after crystallization evidenced that this evolution could be attributed to the disappearing of Ge-C bonds and migration of C atoms out of the GeTe phase upon crystallization, limiting then the growth of GeTe crystallites in C-doped films.

  2. Rapid thermal annealing and modulation-doping effects on InAs/GaAs quantum dots photoluminescence dependence on excitation power

    Energy Technology Data Exchange (ETDEWEB)

    Chaâbani, W. [Laboratoire Matériaux-Molécules et Applications, Institut Préparatoire aux Etudes Scientifiques et Techniques, Université de Carthage, La Marsa 2070 (Tunisia); Melliti, A., E-mail: adnenmelliti@yahoo.fr [Laboratoire Matériaux-Molécules et Applications, Institut Préparatoire aux Etudes Scientifiques et Techniques, Université de Carthage, La Marsa 2070 (Tunisia); Maaref, M.A. [Laboratoire Matériaux-Molécules et Applications, Institut Préparatoire aux Etudes Scientifiques et Techniques, Université de Carthage, La Marsa 2070 (Tunisia); Testelin, C. [Institut des NanoSciences de Paris, UPMC Univ., Paris 06, UMR 7588, F-75005 Paris (France); CNRS, UMR 7588, INSP, F-75005 Paris (France); Lemaître, A. [Laboratoire de Photonique et Nanostructures (LPN), CNRS, Route de Nozay, F-91460 Marcoussis (France)

    2016-07-15

    The optical properties of p-doped and annealed InAs/GaAs quantum dots (QDs) was investigated by photoluminescence (PL) as a function of temperature and excitation power density (P{sub exc}). At low-T, PL spectra of rapid thermal annealing (RTA) and p-modulation doped QDs show an energy blueshift and redshift, respectively. A superlinear dependence of integrated PL intensity on P{sub exc} at high-T was found only for undoped QD. The superlinearity was suppressed by modulation-doping and RTA effects. A linear dependence of I{sub PL} at all temperatures and a decrease of the carrier-carrier Coulomb interaction at high-T was found after RTA.

  3. Modulation of the electron transport properties in graphene nanoribbons doped with BN chains

    Directory of Open Access Journals (Sweden)

    Wu Liu

    2014-06-01

    Full Text Available Using density-functional theory and the non-equilibrium Green's function method, the electron transport properties of zigzag graphene nanoribbons (ZGNRs doped with BN chains are studied by systematically calculating the energy band structure, density of states and the transmission spectra for the systems. The BN chains destroyed the electronic transport properties of the ZGNRs, and an energy gap appeared for the ZGNRs, and displayed variations from a metal to a wide-gap semiconductor. With an increase in the number of BN chains, the band gap increased gradually in the band structure and the transmission coefficient decreased near the Fermi surface. Additionally, the doping position had a significant effect on the electronic properties of the ZGNRs.

  4. Comparing n- and p-type polycrystalline silicon absorbers in thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Deckers, J. [imec, Kapeldreef 75, B-3001 Heverlee, Leuven (Belgium); ESAT, KU Leuven, Kardinaal Mercierlaan 94, B-3001 Heverlee, Leuven (Belgium); Bourgeois, E. [Institute for Materials Research (IMO), Hasselt University, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); IMOMEC, IMEC vzw, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); Jivanescu, M. [Department of Physics and Astronomy, University of Leuven, Celestijnenlaan 200D, B-3001 Heverlee, Leuven (Belgium); Abass, A. [Photonics Research Group (INTEC), Ghent University-imec, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium); Van Gestel, D.; Van Nieuwenhuysen, K.; Douhard, B. [imec, Kapeldreef 75, B-3001 Heverlee, Leuven (Belgium); D' Haen, J.; Nesladek, M.; Manca, J. [Institute for Materials Research (IMO), Hasselt University, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); IMOMEC, IMEC vzw, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); Gordon, I.; Bender, H. [imec, Kapeldreef 75, B-3001 Heverlee, Leuven (Belgium); Stesmans, A. [Department of Physics and Astronomy, University of Leuven, Celestijnenlaan 200D, B-3001 Heverlee, Leuven (Belgium); Mertens, R.; Poortmans, J. [imec, Kapeldreef 75, B-3001 Heverlee, Leuven (Belgium); ESAT, KU Leuven, Kardinaal Mercierlaan 94, B-3001 Heverlee, Leuven (Belgium)

    2015-03-31

    We have investigated fine grained polycrystalline silicon thin films grown by direct chemical vapor deposition on oxidized silicon substrates. More specifically, we analyze the influence of the doping type on the properties of this model polycrystalline silicon material. This includes an investigation of defect passivation and benchmarking of minority carrier properties. In our investigation, we use a variety of characterization techniques to probe the properties of the investigated polycrystalline silicon thin films, including Fourier Transform Photoelectron Spectroscopy, Electron Spin Resonance, Conductivity Activation, and Suns-Voc measurements. Amphoteric silicon dangling bond defects are identified as the most prominent defect type present in these layers. They are the primary recombination center in the relatively lowly doped polysilicon thin films at the heart of the current investigation. In contrast with the case of solar cells based on Czochralski silicon or multicrystalline silicon wafers, we conclude that no benefit is found to be associated with the use of n-type dopants over p-type dopants in the active absorber of the investigated polycrystalline silicon thin-film solar cells. - Highlights: • Comparison of n- and p-type absorbers for thin-film poly-Si solar cells • Extensive characterization of the investigated layers' characteristics • Literature review pertaining the use of n-type and p-type dopants in silicon.

  5. P-type electronic and thermal transport properties of Mg2Sn1-xSix

    Science.gov (United States)

    Kim, Sunphil; Wiendlocha, Bartlomiej; Heremans, Joseph P.

    2013-03-01

    P-type Mg2Sn doped with various acceptors(1)(2) has been studied as a potential thermoelectric material. Because of its narrow band gap and high lattice thermal conductivity, the zT values of the binary compound are limited: zTmax reported is 0.3(3). In this work, we synthesize and characterize p-type-doped Mg2Sn1-xSix with various acceptors. Silicon is added in order to widen the band gap and scatter the phonons. The conduction band degeneracy that yields excellent zT in n-type material in the Mg2Sn1-xSix alloy system unfortunately does not apply to p-type material. Thermomagnetic and galvanomagnetic properties (electrical resistivity, Seebeck, Hall, and Nernst coefficients) are measured, along with thermal conductivity and band gap measurements. Finally, zT values are reported. (1) H. Y. Chen et al. Journal of Electronic Materials, Vol. 38, No. 7, 2009 (2) S. Choi et al. Journal of Electronic Materials, Vol. 41, No. 6, 2012 (3) H. Y. Chen et al. Phys. Status Solidi A 207, No. 11, 2523-2531 (2010) The work is supported by the joint NSF/DOE program on thermoelectrics, NSF-CBET-1048622

  6. Self-amplitude and self-phase modulation of the charcoal mode-locked erbium-doped fiber lasers.

    Science.gov (United States)

    Lin, Yung-Hsiang; Lo, Jui-Yung; Tseng, Wei-Hsuan; Wu, Chih-I; Lin, Gong-Ru

    2013-10-21

    With the intra-cavity nano-scale charcoal powder based saturable absorber, the 455-fs passive mode-locking of an L-band erbium-doped fiber laser (EDFL) is demonstrated. The size reduction of charcoal nano-particle is implemented with a simple imprinting-exfoliation-wiping method, which assists to increase the transmittance up to 0.91 with corresponding modulation depth of 26%. By detuning the power gain from 17 to 21 dB and cavity dispersion from -0.004 to -0.156 ps² of the EDFL, the shortening of mode-locked pulsewidth from picosecond to sub-picosecond by the transformation of the pulse forming mechanism from self-amplitude modulation (SAM) to the combining effect of self-phase modulation (SPM) and group delay dispersion (GDD) is observed. A narrower spectrum with 3-dB linewidth of 1.83-nm is in the SAM case, whereas the spectral linewidth broadens to 5.86 nm with significant Kelly sideband pair can be observed if the EDFL enters into the SPM regime. The mode-locking mechanism transferred from SAM to SPM/GDD dominates the pulse shortening procedure in the EDFL, whereas the intrinsic defects in charcoal nano-particle only affect the pulse formation at initial stage. The minor role of the saturable absorber played in the EDFL cavity with strongest SPM is observed.

  7. The use of nonlinear dynamics of erbium-doped fiber laser at pump modulation for intra-cavity sensing

    Science.gov (United States)

    Arellano-Sotelo, H.; Kir'yanov, A. V.; Barmenkov, Yu. O.; Aboites, V.

    2011-02-01

    We report the use of nonlinear dynamics of an erbium-doped fiber laser (EDFL) at pump modulation, namely the period-1 pulsed regime, for intra-cavity loss sensing and demonstrate noticeable sensitivity enhancement of an EDFL-based sensor, provided by this arrangement. Experimentally, we obtain a ten-fold increase of the sensor response, i.e. peak-to-peak pulse amplitude against loss variation, as compared with the standard sensing schemes using a low-power wide-spectrum light emitting diode (LED) or fiber laser without external modulation. This advantage originates from a strong dependence of pulse amplitude in the period-1 regime on intra-cavity loss variable that is, in turn, determined by the interrelation of relaxation frequency (an internal EDFL parameter) and frequency and depth of external (pump) modulation. A modeling of the EDFL-based sensor, presented for the case when the laser operates in the period-1 regime, allows an insight into the sensor operation details and opens the gate to its further optimization. The proposed sensing method seems to be a proper choice for the applications where an intra-cavity sensor's head has high internal loss (≥10 dB) while sensed loss is varied within a quite narrow range (a few dB).

  8. Fabrication of p-type ZnSe:Sb nanowires for high-performance ultraviolet light photodetector application.

    Science.gov (United States)

    Nie, Biao; Luo, Lin-Bao; Chen, Jing-Jing; Hu, Ji-Gang; Wu, Chun-Yan; Wang, Li; Yu, Yong-Qiang; Zhu, Zhi-Feng; Jie, Jian-Sheng

    2013-03-08

    p-type ZnSe nanowires (NWs) with tunable electrical conductivity were fabricated on a large scale by evaporating a mixed powder composed of ZnSe and Sb in different ratios. According to the structural characterization, the Sb-doped ZnSe NWs are of single crystalline form and grow along the [001] direction. The presence of Sb in the ZnSe NWs was confirmed by XPS spectra. Electrical measurement of a single ZnSe:Sb NW based back-gate metal-oxide field-effect-transistor reveals that all the doped NWs exhibit typical p-type conduction characteristics, and the conductivity can be tuned over eight orders of magnitude, from 6.36 × 10(-7) S cm(-1) for the undoped sample to ∼37.33 S cm(-1) for the heavily doped sample. A crossed p-n nano-heterojunction photodetector made from the as-doped nanostructures displays pronounced rectification behavior, with a rectification ratio as high as 10(3) at ±5 V. Remarkably, it exhibits high sensitivity to ultraviolet light illumination with good reproducibility and quick photoresponse. Finally, the work mechanism of such a p-n junction based photodetector was elucidated. The generality of the above result suggests that the as-doped p-type ZnSe NWs will find wide application in future optoelectronics devices.

  9. Rare Earth Doped GaN Laser Structures Using Metal Modulated Epitaxy

    Science.gov (United States)

    2015-03-30

    Doped Gallium Nitride by Plasma Assisted MBE, Ph. D. Thesis in Electrical and Computer Engineering, 2007, Georgia Institute of Technology, Atlanta...PERCENT_SUPPORTEDNAME FTE Equivalent: Total Number: ...... ...... Inventions (DD882) Scientific Progress Gallium nitride is a well-known wide bandgap III/V...Rui Wang for generously sharing his knowledge and experience in MBE, SIMS and nitride semiconductors. The discussions I was fortunate enough to have

  10. Microstrain in modulation-doped Al sub x Ga sub 1 sub - sub x N/GaN heterostructures

    CERN Document Server

    Tan Wei Shi; Shen Bo; Cai Hong Ling; Wu Xiao Shan; Jiang Shu Sheng; Zheng Wen Li; Jia Quan Jie; Jiang Xiao Ming

    2002-01-01

    Modulation-doped Al sub x Ga sub 1 sub - sub x N/GaN heterostructures with various thickness of Si-doped n-Al sub 0 sub . sub 2 sub 2 Ga sub 0 sub . sub 7 sub 8 N barrier (n-AlGaN) were deposited on (0001)-oriented sapphire (alpha-Al sub 2 O sub 3) by MOCVD. The reciprocal space mappings (RSMs) of symmetric reflection (0002) and asymmetric reflection (1014) were measured with the methods of high resolution X-ray diffraction (HRXRD). The results indicate that the microstructure and strain status of barrier correlate to those of the i-GaN layer. The strained barrier starts to be relaxed while its thickness is larger than 750 Angstrom and the critical thickness t sub c is larger than 500 Angstrom. The barrier holds an 'abnormal' relaxation status, which probably results from the internal defects of n-AlGaN and the strain relaxation status at the i-GaN/alpha-Al sub 2 O sub 3 interfaces

  11. Modulation transfer function characteristic of uniform-doping transmission-mode GaAs/GaAlAs photocathode

    Institute of Scientific and Technical Information of China (English)

    Ren Ling; Chang Ben-Kang

    2011-01-01

    The resolution characteristic can be obtained by the modulation transfer function(MTF)of a GaAs/GaAlAs photocathode.After establishing the theoretical model of GaAs(100)-oriented atomic configuration and the formula for the ionized impurity scattering of the non-equilibrium carriers,this paper calculates the trajectories of photoelectrons in a photocathode.Thus the distribution of photoelectron spots on the emit-face is obtained,which is namely the point spread function.The MTF is obtained by Fourier transfer of the line spread function obtained from the point spread function.The MTF obtained from these calculations is shown to depend heavily on the electron diffusion length,and enhanced considerably by decreasing the electron diffusion length and increasing the doping concentration.Furthermore,the resolution is enhanced considerably by increasing the active-layer thickness,especially at high spatial frequencies.The best spatial resolution is 860 lp/mm,for the GaAs photocathode of doping concentration 1×1019cm-3,electron diffusion length 3.6 μm and the active-layer thickness 2 μm,under the 633-nm light irradiated. This research will contribute to the future improvement of the cathode's resolution for preparing a high performance GaAs photocathode,and improve the resolution of a low light level image intensifier.

  12. Complex quantum transport in a modulation doped strained Ge quantum well heterostructure with a high mobility 2D hole gas

    Science.gov (United States)

    Morrison, C.; Casteleiro, C.; Leadley, D. R.; Myronov, M.

    2016-09-01

    The complex quantum transport of a strained Ge quantum well (QW) modulation doped heterostructure with two types of mobile carriers has been observed. The two dimensional hole gas (2DHG) in the Ge QW exhibits an exceptionally high mobility of 780 000 cm2/Vs at temperatures below 10 K. Through analysis of Shubnikov de-Haas oscillations in the magnetoresistance of this 2DHG below 2 K, the hole effective mass is found to be 0.065 m0. Anomalous conductance peaks are observed at higher fields which deviate from standard Shubnikov de-Haas and quantum Hall effect behaviour due to conduction via multiple carrier types. Despite this complex behaviour, analysis using a transport model with two conductive channels explains this behaviour and allows key physical parameters such as the carrier effective mass, transport, and quantum lifetimes and conductivity of the electrically active layers to be extracted. This finding is important for electronic device applications, since inclusion of highly doped interlayers which are electrically active, for enhancement of, for example, room temperature carrier mobility, does not prevent analysis of quantum transport in a QW.

  13. Mass spectrometric characterization of urinary metabolites of the selective androgen receptor modulator andarine (S-4) for routine doping control purposes.

    Science.gov (United States)

    Thevis, Mario; Thomas, Andreas; Fusshöller, Gregor; Beuck, Simon; Geyer, Hans; Schänzer, Wilhelm

    2010-08-15

    Selective androgen receptor modulators (SARMs) are potent anabolic agents with tissue-selective properties. Due to their potential misuse in elite sport, the World Anti-Doping Agency (WADA) has prohibited SARMs since 2008, and although no representative drug candidate has yet received full clinical approval, recent findings of SARMs illegally sold via the internet have further supported the need to efficiently test for these compounds in doping controls. In the present communication, the mass spectrometric characterization of urinary metabolites of the SARM Andarine (also referred to as S-4) compared with earlier in vitro and animal studies is reported. Liquid chromatography interfaced to high-resolution/high-accuracy (tandem) mass spectrometry was used to identify phase I and II metabolites, confirming the predicted target analytes for sports drug testing purposes including the glucuronic acid conjugates of the active drug, its monohydroxylated and/or deacetylated product, the hydrolysis product resulting from the removal of the compound's B-ring, as well as the sulfate of the monohydroxylated and the deacetylated phase I metabolite. The obtained data will support future efforts to effectively screen for and confirm the misuse of the non-approved drug candidate Andarine. Copyright (c) 2010 John Wiley & Sons, Ltd.

  14. Effect of an in-plane magnetic field on the photoluminescence spectrum of modulation-doped quantum wells and heterojunctions

    Science.gov (United States)

    Ashkinadze, B. M.; Linder, E.; Cohen, E.; Pfeiffer, L. N.

    2005-01-01

    The photoluminescence (PL) spectrum of modulation-doped GaAs/AlGaAs quantum wells and heterojunctions (HJ) is studied under a magnetic field (B‖) applied parallel to the two-dimensional electron gas (2DEG) layer. The effect of B‖ strongly depends on the electron-hole separation, and we revealed remarkable B‖ -induced modifications of the PL spectra in both types of heterostructures. A model considering the direct optical transitions between the conduction and valence subbands that are shifted in k -space under B‖ , accounts qualitatively for the observed spectral modifications. In the HJs, the 2DEG-hole PL intensity is strongly enhanced relatively to the bulk exciton PL with increasing B‖ . This means that the distance between the photoholes and the 2DEG decreases with increasing B‖ , and thus free holes are responsible for the 2DEG-hole PL.

  15. Growth and Characterization of Modulation-Doped AlxGa1-xN/GaN Heterostructures

    Institute of Scientific and Technical Information of China (English)

    沈波; 张荣; 施毅; 郑有炓; T. Someya; Y. Arakawa

    2001-01-01

    The modulation-doped Al0.22Ga0.78N/GaN heterostructures with different Al0.22Ga0.78N barrier thicknesses were grown by means of metal-organic chemical vapour deposition. The Al0.22Ga0. 78N layer still has pseudomorphic growth when its thickness is 53nm. The mobility of the two-dimensional electron gas (2DEG) at the heterointerfaces is much higher than that of the electrons in GaN films at both 300 and 77K. The dramatic decrease of the 2DEG mobility in an Al0.22Ga0.78N/GaN heterostructure corresponds to the partial relaxation of the Al0.22 Ga0.78N barrier.

  16. The generation of Q-switched erbium-doped fiber laser using black phosphorus saturable absorber with 8% modulation depth

    Science.gov (United States)

    Fauziah, C. M.; Rosol, A. H. A.; Latiff, A. A.; Harun, S. W.

    2017-06-01

    We report a generation of the Q-switched laser operating in 1.55-micron region by using black phosphorus (BP) as a saturable absorber (SA). A 980-nm laser diode was pumped into Erbium-doped fiber (EDF) gain medium in ring cavity configuration. The BP-based SA was prepared by mechanically exfoliating the BP crystal using scotch tape. The obtained BP-tape SA has a modulation depth of 8 %. To realize a Q-switching operation, a small piece of the tape is then integrated into between two fiber ferrule tips. A stable Q-switching operation started at 40 mW. The maximum repetition rate obtainable at 28.57 kHz, with pulse width of 5.35 μs. This finding shows the BP is one of the promising material to work as an SA for pulsed laser generation.

  17. Q-switched mode-locking of an erbium-doped fiber laser using cavity modulation frequency detuning.

    Science.gov (United States)

    Chang, You Min; Lee, Junsu; Jhon, Young Min; Lee, Ju Han

    2012-07-20

    We present the results of an investigation regarding a Q-switched mode-locked fiber laser scheme based on a cavity modulation frequency detuning technique. The approach is based on undamped laser relaxation oscillations occurring due to frequency detuning in the fundamental cavity resonance frequency. Through a range of experiments with an erbium-doped, fiber-based, ring-cavity laser, this approach has been shown to be capable of generating high-quality Q-switched mode-locked pulses from an optical fiber-based laser. The maximum frequency detuning range for a stable Q-switched mode-locking operation has been observed to vary depending on the pump power used. We found that the highest pulse peak power was obtained at the frequency detuning threshold at which the operation changed from the mode-locking to the Q-switched mode-locking regime.

  18. Realization of Ag-S codoped p-type ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tian Ning, E-mail: xtn9886@zju.edu.cn [Department of Science, Zhijiang College of Zhejiang University of Technology, Hangzhou, Zhejiang 310024 (China); Department of Physics, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Li, Xiang; Lu, Zhong [Department of Science, Zhijiang College of Zhejiang University of Technology, Hangzhou, Zhejiang 310024 (China); Chen, Yong Yue [Department of Physics, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Sui, Cheng Hua [Department of Science, Zhijiang College of Zhejiang University of Technology, Hangzhou, Zhejiang 310024 (China); Wu, Hui Zhen [Department of Physics, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China)

    2014-10-15

    Highlights: • Ag-S codoped p-type ZnO thin films have been fabricated. • The films exhibit low resistivity and high Hall mobility and hole concentration. • A ZnO:(Ag, S)/i-ZnO/ZnO:Al homojunction has been fabricated and shows rectifying behaviors. - Abstract: Ag-S codoped ZnO films have been grown on quartz substrates by e-beam evaporation at low temperature (100 °C). The effects of Ag{sub 2}S content on the structural and electrical properties of the films were investigated. The results showed that 2 wt% Ag{sub 2}S doped films exhibited p-type conduction, with a resistivity of 0.0347 Ω cm, a Hall mobility of 9.53 cm{sup 2} V{sup −1} s{sup −1}, and a hole concentration of 1.89 × 10{sup 19} cm{sup −3} at room temperature. The X-ray photoelectron spectroscopy measurements showed that Ag and S have been incorporated into the films. To further confirm the p-type conduction of Ag-S codoped ZnO films, a ZnO:(Ag, S)/i-ZnO/ZnO:Al homojunction was fabricated and rectifying behaviors of which was measured. High electrical performance and low growth temperature indicate that Ag{sub 2}S is a promising dopant to fabricate p-type Ag-S codoped ZnO films.

  19. 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.

  20. 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%.

  1. Above bandgap luminescence of p-type GaAs epitaxial layers

    Science.gov (United States)

    Sapriel, J.; Chavignon, J.; Alexandre, F.; Azoulay, R.; Sermage, B.; Rao, K.; Voos, M.

    1991-08-01

    New photoluminescence bands are observed in p-type GaAs epitaxial layers at 300 and 80 K, above the bandgap. These bands are independent of the nature of the dopant (Zn, Be, C) and of the growth technique (MBE or MOCVD). Their intensities increase as a function of the p doping (1 × 10 17 < p < 2 × 10 20cm-3) and peak at energies which correspond to transitions between the Γ 6, L 6 and X 6 minima of the conduction band and the Γ 8 and Γ 7 maxima of the valence band.

  2. 27Al fourier-transform electron-spin-echo modulation of Cu 2+-doped zeolites A and X

    Science.gov (United States)

    Goldfarb, Daniella; Kevan, Larry

    Cu 2+-doped NaA, CaA, and NaX zeolites were studied using the electron-spin-echo modulation (ESEM) method. In both hydrated and dehydrated samples 27Al modulation has been observed. The time-domain ESEM traces were Fourier transformed and analyzed in the frequency domain. All FT-ESEM spectra of the hydrated samples showed a single peak at the Larmor frequency of 27Ai, indicating that the zeeman interaction is dominant and that the 27Al quadrupole and hyperfine interactions are relatively small. Considerable changes in the spectrum appear upon dehydration. Several frequencies significantly different from the Larmor frequency appear and the spectrum depends on the major cocation present. The major features of the spectra of the dehydrated zeolites could be theoretically reproduced, using exact diagonalization of the nuclear Hamiltonian, with relatively large isotropic hyperfine and quadrupole coupling constants. For example, in CuCaA and CuNaA zeolites the isotropic hyperfine constant is in the range of 0.2-0.5 and 0.8-1.0 MHz, respectively, with the quadrupole coupling constant in the range of 6-10 MHz for both.

  3. Multifunctional tunable multiwavelength erbium-doped fiber laser based on tunable comb filter and intensity-dependent loss modulation

    Science.gov (United States)

    Quan, Mingran; Li, Yuan; Tian, Jiajun; Yao, Yong

    2015-04-01

    A multiwavelength erbium-doped fiber laser based on tunable comb spectral filter and intensity-dependent loss modulation is proposed and experimentally demonstrated. The laser allows fine and multifunctional tunable operations of channel-spacing, peak-location, spectral-range, and wavelength-number. More specifically, channel-spacing switch from 0.4 nm to 0.2 nm and peak-location adjustment within half of free spectrum range are obtained via controlling the tunable comb filter. The wavelength-number and the spectral-range of the lasing lines can be accurately controlled by intensity-dependent loss modulation in the laser cavity, enabled by a power-symmetric nonlinear optical loop mirror. In addition, fine control over the wavelength-number at fixed spectral-range is realized by simply adjusting the pump power. More important, the tunable operation process for every type of specific parameter is individual, without influences for other output parameters. Such features of this fiber laser make it useful and convenient for the practical application.

  4. Samarium Doped Cerium Oxide Clusters: a Study on the Modulation of Electronic Structure

    Science.gov (United States)

    Topolski, Josey E.; Kafader, Jared O.; Marrero-Colon, Vicmarie; Chick Jarrold, Caroline

    2017-06-01

    Cerium oxide is known for its use in solid oxide fuel cells due to its high ionic conductivity. The doping of trivalent samarium atoms into cerium oxide is known to enhance the ionic conductivity through the generation of additional oxygen vacancies. This study probes the electronic structure of Sm_{x}Ce_{y}O_{z} (x+y=3, z=2-4) anion and neutral clusters. Anion photoelectron spectra of these mixed metal clusters exhibit additional spectral features not present in the previously studied cerium oxide clusters. Density functional theory calculations have been used to aid interpretation of collected spectra. The results of this work can be used to inform the design of materials used for solid oxide fuel cells.

  5. Design of P-Type Cladding Layers for Tunnel-Injected UVA Light Emitting Diodes

    CERN Document Server

    Zhang, Yuewei; Akyol, Fatih; Allerman, Andrew A; Moseley, Michael W; Armstrong, Andrew M; Rajan, Siddharth

    2016-01-01

    We discuss the engineering of p-AlGaN cladding layers for achieving efficient tunnel-injected III-Nitride ultraviolet light emitting diodes (UV LEDs) in the UV-A spectral range. We show that capacitance-voltage measurements can be used to estimate the compensation and doping in p-AlGaN layers located between the multi-quantum well region and the tunnel junction layer. By increasing the p-type doping concentration to overcome the background compensation, on-wafer external quantum efficiency and wall-plug efficiency of 3.37% and 1.62% were achieved for tunnel-injected UV LEDs emitting at 325 nm. We also show that interband tunneling hole injection can be used to realize UV LEDs without any acceptor doping. The work discussed here provides new understanding of hole doping and transport in AlGaN-based UV LEDs, and demonstrates the excellent performance of tunnel-injected LEDs for the UV-A wavelength range.

  6. Simulation of Enhancement Mode GaN HEMTs with Threshold > 5 V using P-type Buffer

    CERN Document Server

    Bajaj, Sanyam; Krishnamoorthy, Sriram; Hung, Ting-Hsiang; Rajan, Siddharth

    2015-01-01

    A high threshold voltage enhancement-mode GaN HEMT with p-type doped buffer is discussed and simulated. Analytical expressions are derived to explain the role of buffer capacitance in designing and enhancing threshold voltage. Simulations of the proposed device with p-type buffer show threshold voltages above 5 V, and a positive shift in threshold voltage as the oxide capacitance is reduced, thus enabling threshold voltage tunability over an unprecedented range for GaN-based HEMTs. The electric field profiles, breakdown performance, on-resistance and delay tradeoffs in the proposed pGaN back HEMT device are also discussed.

  7. Nitrogen-doped carbon nanoparticle modulated turn-on fluorescent probes for histidine detection and its imaging in living cells

    Science.gov (United States)

    Zhu, Xiaohua; Zhao, Tingbi; Nie, Zhou; Miao, Zhuang; Liu, Yang; Yao, Shouzhuo

    2016-01-01

    In this work, nitrogen-doped carbon nanoparticle (N-CNP) modulated turn-on fluorescent probes were developed for rapid and selective detection of histidine. The as synthesized N-CNPs exhibited high fluorescence quantum yield and excellent biocompatibility. The fluorescence of N-CNPs can be quenched selectively by Cu(ii) ions with high efficiency, and restored by the addition of histidine owing to the competitive binding of Cu(ii) ions and histidine that removes Cu(ii) ions from the surface of the N-CNPs. Under the optimal conditions, a linear relationship between the increased fluorescence intensity of N-CNP/Cu(ii) ion conjugates and the concentration of histidine was established in the range from 0.5 to 60 μM. The detection limit was as low as 150 nM (signal-to-noise ratio of 3). In addition, the as-prepared N-CNP/Cu(ii) ion nanoprobes showed excellent biocompatibility and were applied for a histidine imaging assay in living cells, which presented great potential in the bio-labeling assay and clinical diagnostic applications.In this work, nitrogen-doped carbon nanoparticle (N-CNP) modulated turn-on fluorescent probes were developed for rapid and selective detection of histidine. The as synthesized N-CNPs exhibited high fluorescence quantum yield and excellent biocompatibility. The fluorescence of N-CNPs can be quenched selectively by Cu(ii) ions with high efficiency, and restored by the addition of histidine owing to the competitive binding of Cu(ii) ions and histidine that removes Cu(ii) ions from the surface of the N-CNPs. Under the optimal conditions, a linear relationship between the increased fluorescence intensity of N-CNP/Cu(ii) ion conjugates and the concentration of histidine was established in the range from 0.5 to 60 μM. The detection limit was as low as 150 nM (signal-to-noise ratio of 3). In addition, the as-prepared N-CNP/Cu(ii) ion nanoprobes showed excellent biocompatibility and were applied for a histidine imaging assay in living cells, which

  8. Electronic inhomogeneity in n- and p-type PbTe detected by 125Te NMR

    Science.gov (United States)

    Levin, E. M.; Heremans, J. P.; Kanatzidis, M. G.; Schmidt-Rohr, K.

    2013-09-01

    125Te nuclear magnetic resonance spectra and spin-lattice relaxation of n- and p-type PbTe, self-doping narrow band-gap semiconductors, have been studied and compared to those of p-type GeTe. Spin-lattice relaxation in GeTe can be fit by one component, while that in both PbTe samples must be fit by at least two components, showing electronically homogeneous and inhomogeneous materials, respectively. For PbTe-based materials, the spin-lattice relaxation rate 1/T1 increases linearly with carrier concentration. The data for GeTe fall on the same line and allow us to extend this plot to higher concentrations. Long and short T1 components in both PbTe samples reflect “low,” ˜1017 cm-3, and “high,” ˜1018 cm-3, carrier concentration components. Carrier concentrations in both n- and p-type PbTe samples obtained from the Hall and Seebeck effects generally match the “high” carrier concentration component, and to some extent, ignore the “low” one. This demonstrates that the Hall and Seebeck effects may have a limited ability for the determination of carrier concentration in complex thermoelectric PbTe-based and other multicomponent materials.

  9. Enhanced photo-assisted electrical gating in vanadium dioxide based on saturation-induced gain modulation of erbium-doped fiber amplifier.

    Science.gov (United States)

    Lee, Yong Wook; Kim, Bong-Jun; Choi, Sungyoul; Lee, Yong Wan; Kim, Hyun-Tak

    2009-10-26

    By incorporating saturation-induced gain modulation of an erbium-doped fiber amplifier (EDFA), we have demonstrated a high-speed photo-assisted electrical gating with considerably enhanced switching characteristics in a two-terminal device fabricated by using vanadium dioxide thin film. The gating operation was performed by illuminating the output light of the EDFA, whose transient gain was modulated by adjusting the chopping frequency of the input light down to 1 kHz, onto the device. In the proposed gating scheme, gated signals with a temporal duration of approximately 40 micros were successively generated at a repetition rate of 1 kHz.

  10. Quasi-perpetual discharge behaviour in p-type Ge-air batteries.

    Science.gov (United States)

    Ocon, Joey D; Kim, Jin Won; Abrenica, Graniel Harne A; Lee, Jae Kwang; Lee, Jaeyoung

    2014-11-07

    Metal-air batteries continue to become attractive energy storage and conversion systems due to their high energy and power densities, safer chemistries, and economic viability. Semiconductor-air batteries - a term we first define here as metal-air batteries that use semiconductor anodes such as silicon (Si) and germanium (Ge) - have been introduced in recent years as new high-energy battery chemistries. In this paper, we describe the excellent doping-dependent discharge kinetics of p-type Ge anodes in a semiconductor-air cell employing a gelled KOH electrolyte. Owing to its Fermi level, n-type Ge is expected to have lower redox potential and better electronic conductivity, which could potentially lead to a higher operating voltage and better discharge kinetics. Nonetheless, discharge measurements demonstrated that this prediction is only valid at the low current regime and breaks down at the high current density region. The p-type Ge behaves extremely better at elevated currents, evident from the higher voltage, more power available, and larger practical energy density from a very long discharge time, possibly arising from the high overpotential for surface passivation. A primary semiconductor-air battery, powered by a flat p-type Ge as a multi-electron anode, exhibited an unprecedented full discharge capacity of 1302.5 mA h gGe(-1) (88% anode utilization efficiency), the highest among semiconductor-air cells, notably better than new metal-air cells with three-dimensional and nanostructured anodes, and at least two folds higher than commercial Zn-air and Al-air cells. We therefore suggest that this study be extended to doped-Si anodes, in order to pave the way for a deeper understanding on the discharge phenomena in alkaline metal-air conversion cells with semiconductor anodes for specific niche applications in the future.

  11. Optical investigation of InAs quantum dots inserted in AlGaAs/GaAs modulation doped heterostructure

    Science.gov (United States)

    Khmissi, H.; Baira, M.; Sfaxi, L.; Bouzaïene, L.; Saidi, F.; Bru-Chevallier, C.; Maaref, H.

    2011-03-01

    Optical properties of InAs quantum dots (QDs) inserted in AlGaAs/GaAs modulation doped heterostructure are investigated. To study the effect of carrier transfer behavior on the luminescence of self-assembled quantum dots, a series of sample has been prepared using molecular beam epitaxy (Riber 32 system) in which we have varied the thickness separating the delta dopage and the InAs quantum dots layer. Photoluminescence spectra show the existence of two peaks that can be attributed to transition energies from the ground state (E1-HH1) and the first excited state (E2-HH2). Two antagonist effects have been observed, a blue shift of the emission energies result from electron transferred from the AlGaAs/GaAs heterojunction to the InAs quantum dots and a red shift caused by the quantum confined Stark effect due to the internal electric field existing In the AlGaAs/GaAs heterojunction.

  12. Realization of stable p-type ZnO thin films using Li-N dual acceptors

    Energy Technology Data Exchange (ETDEWEB)

    Rao, T. Prasada, E-mail: prasadview@gmail.com [Advanced Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli- 620 015 (India); Kumar, M.C. Santhosh, E-mail: santhoshmc@nitt.edu [Advanced Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli- 620 015 (India)

    2011-09-01

    Highlights: > We have presented a promising Li-N dual acceptor doping method to realize p-type ZnO films via spray pyrolysis. > The influence of concentration of Li-N on the structural, electrical, and optical properties of p-type ZnO:(Li, N) films were investigated in detail. > It is found that (Li, N):ZnO films deposited on glass substrate show the preferential orientation of (002) plane. > The Hall Effect measurements exhibited p-type behaviour on (Li, N):ZnO thin films and the stability of the samples were verified by aging studies. - Abstract: Lithium and nitrogen dual acceptors-doped p-type ZnO thin films have been prepared using spray pyrolysis technique. The influence of dual acceptor (Li, N) doping on the structural, electrical, and optical properties of (Li, N):ZnO films are investigated in detail. The (Li, N):ZnO films exhibit good crystallinity with a preferred c-axis orientation. From AFM studies, it is found that the surface roughness of the thin films increases with the increase of doping percentage. The Hall Effect measurements showed p-type conductivity. The Hall measurements have been performed periodically up to seven months and it is observed that the films show p-type conductivity throughout the period of observation. The samples with Li:N ratio of 8:8 mol% showed the lowest resistivity of 35.78 {Omega} cm, while sample with Li:N ratio of 6:6 mol% showed highest carrier concentration. The PL spectra of (Li, N):ZnO films show a strong UV emission at room temperature. Furthermore, PL spectra show low intensity in deep level transition, indicating a low density of native defects. This indicates that the formation of intrinsic defects is effectively suppressed by dual acceptor (Li, N) doping in ZnO thin films. The chemical bonding states of N and Li in the films were examined by XPS analysis.

  13. Imparting electroactivity to polycaprolactone fibers with heparin-doped polypyrrole: Modulation of hemocompatibility and inflammatory responses.

    Science.gov (United States)

    Xiong, Gordon M; Yuan, Shaojun; Wang, Jun Kit; Do, Anh Tuan; Tan, Nguan Soon; Yeo, Kiat Seng; Choong, Cleo

    2015-09-01

    Hemocompatibility, anti-inflammation and anti-thrombogenicity of acellular synthetic vascular grafts remains a challenge in biomaterials design. Using electrospun polycaprolactone (PCL) fibers as a template, a coating of polypyrrole (PPy) was successfully polymerized onto the fiber surface. The fibers coated with heparin-doped PPy (PPy-HEP) demonstrated better electroactivity, lower surface resistivity (9-10-fold) and better anti-coagulation response (non-observable plasma recalcification after 30min vs. recalcification at 8-9min) as compared to fibers coated with pristine PPy. Red blood cell compatibility, measured by% hemolysis, was greatly improved on PPy-HEP-coated PCL in comparison to uncoated PCL (3.9±2.1% vs. 22.1±4.1%). PPy-HEP-coated PCL fibers also exhibited higher stiffness values (6.8±0.9MPa vs. 4.2±0.8MPa) as compared to PCL fibers, but similar tensile strengths. It was also observed that the application of a low alternating current led to a 4-fold reduction of platelet activation (as quantitated by CD62p expression) for the PPy-HEP-coated fibers as compared to non-stimulated conditions. In parallel, a reduction in the leukocyte adhesion to both pristine PPy-coated and PPy-HEP-coated fibers was observable with AC stimulation. Overall, a new strategy involving the use of hemocompatible conducting polymers and electrical stimulation to control thrombogenicity and inflammatory responses for synthetic vascular graft designs was demonstrated. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  14. Raman spectra of p-type transparent semiconducting Cr{sub 2}O{sub 3}:Mg

    Energy Technology Data Exchange (ETDEWEB)

    Fleischer, Karsten, E-mail: fleisck@tcd.ie; Caffrey, David; Farrell, Leo; Norton, Emma; Mullarkey, Daragh; Arca, Elisabetta; Shvets, Igor V.

    2015-11-02

    We present an analysis of the Raman spectra of p-type transparent conducting Cr{sub 2}O{sub 3}:Mg grown by various techniques including spray pyrolysis, pulsed laser deposition, molecular beam epitaxy and reactive magnetron sputtering. The best performing films show a distinct broad range Raman signature related to defect-induced vibrational modes not seen in stoichiometric, undoped material. Our comparative study demonstrates that Raman spectroscopy can quantify unwanted dopant clustering in the material at high Mg concentrations, while also being sensitive to the Mg incorporation site. By correlating the Raman signature to the electrical properties of the films, growth processes can be optimised to give the best conducting films and the local defect structure for effective p-type doping can be studied. - Highlights: • Mg doping in Cr{sub 2}O{sub 3} can lead to dopant clustering in MgCr{sub 2}O{sub 4} phase. • Post-annealing in oxygen can dissolve these clusters improving doping. • High oxygen pressures during growth can prevent dopant clustering. • Raman spectroscopy is a powerful tool to assist growth optimization in p-type oxides.

  15. Chemically modulated multiferroicity in Dy-doped Gd2Ti2O7

    Science.gov (United States)

    Lin, L.; Zhao, Z. Y.; Liu, D.; Xie, Y. L.; Dong, S.; Yan, Z. B.; Liu, J.-M.

    2013-05-01

    The ferroelectricity and magnetoelectric coupling of Gd2Ti2O7 and Gd2-xDyxTi2O7 with Dy3+ substitution of Gd3+ are investigated. For Gd2Ti2O7, a ferroelectric polarization emerges at ˜30 K and is only ˜1.80 μC/m2 at 2 K, while the magnetoelectric response is quite weak. The Dy3+ substitution in Gd2-xDyxTi2O7, however, results in significant enhancement of polarization with remarkable magnetoelectric response up to 35% at 2 K under a magnetic field of 9 T, suggesting the multiferroicity of Gd2-xDyxTi2O7. It is understood that the chemical modulation of the multiferroicity is basically related to the extreme sensitivity of the spin-spin interactions in this highly frustrated system.

  16. Validity of Rigid-Band Approximation in the Study of Thermoelectric Properties of p-Type FeNbSb-Based Half-Heusler Compounds

    Science.gov (United States)

    Fang, Teng; Zheng, Shuqi; Zhou, Tian; Chen, Hong; Zhang, Peng

    2016-11-01

    Recently, we calculated the thermoelectric properties of p-type FeNbSb half-Heusler compounds by employing the rigid-band approximation (RBA) (Fang et al., RSC Adv 6:10507-10512, 2016). Traditionally, the RBA is used to understand and guide doping in semiconductors. It is therefore important to verify its reliability. To this end, we have investigated the validity of the RBA in heavily doped p-type FeNbSb by calculating the electronic structure and Seebeck coefficient of pure and Ti-, Zr-, Hf-, and Ce-doped FeNbSb using ab initio calculations. The results confirm that Ti, Zr, and Hf doping at Nb site shows rigid-band-like behavior, unlike Ce doping, which changes the density of states. We also calculated the electrical transport properties of the doped systems, indicating that the power factor of Ce-doped FeNbSb is lower than those of Ti-, Zr-, and Hf-doped FeNbSb.

  17. Thin-film metallic glass: an effective diffusion barrier for Se-doped AgSbTe2 thermoelectric modules

    Science.gov (United States)

    Yu, Chia-Chi; Wu, Hsin-Jay; Deng, Ping-Yuan; Agne, Matthias T.; Snyder, G. Jeffrey; Chu, Jinn P.

    2017-03-01

    The thermal stability of joints in thermoelectric (TE) modules, which are degraded during interdiffusion between the TE material and the contacting metal, needs to be addressed in order to utilize TE technology for competitive, sustainable energy applications. Herein, we deposit a 200 nm-thick Zr-based thin-film metallic glass (TFMG), which acts as an effective diffusion barrier layer with low electrical contact resistivity, on a high-zT Se-doped AgSbTe2 substrate. The reaction couples structured with TFMG/TE are annealed at 673 K for 8-360 hours and analyzed by electron microscopy. No observable IMCs (intermetallic compounds) are formed at the TFMG/TE interface, suggesting the effective inhibition of atomic diffusion that may be attributed to the grain-boundary-free structure of TFMG. The minor amount of Se acts as a tracer species, and a homogeneous Se-rich region is found nearing the TFMG/TE interface, which guarantees satisfactory bonding at the joint. The diffusion of Se, which has the smallest atomic volume of all the elements from the TE substrate, is found to follow Fick’s second law. The calculated diffusivity (D) of Se in TFMG falls in the range of D~10-20-10-23(m2/s), which is 106~107 and 1012~1013 times smaller than those of Ni [10-14-10-17(m2/s)] and Cu [10-8-10-11(m2/s)] in Bi2Te3, respectively.

  18. Final Report for Award DE-SC0005403. Improved Electrochemical Performance of Strained Lattice Electrolytes via Modulated Doping

    Energy Technology Data Exchange (ETDEWEB)

    Hertz, Joshua L. [Univ. of Delaware, Newark, DE (United States); Prasad, Ajay K. [Univ. of Delaware, Newark, DE (United States)

    2015-09-06

    The enclosed document provides a final report to document the research performed at the University of Delaware under Grant DE-SC0005403: Improved Electrochemical Performance of Strained Lattice Electrolytes via Modulated Doping. The ultimate goal of this project was to learn how to systematically strain the inter-atomic distance in thin ceramic films and how to use this newfound control to improve the ease by which oxygen ions can conduct through the films. Increasing the ionic conductivity of ceramics holds the promise of drastic improvements in the performance of solid oxide fuel cells, chemical sensors, gas permeation membranes, and related devices. Before this work, the experimental evidence advocating for strain-based techniques was often controversial and poorly characterized. Enabling much of this work was a new method to quickly create a very wide range of ceramic nanostructures that was established during the first phase of the project. Following this initial phase, we created a variety of promising nanostructured epitaxial films and multilayers with systematic variations in lattice mismatch and dopant content. Over the course of the work, a positive effect of tensile atomic strain on the oxygen conductivity was conclusively found using a few different forms of samples and experimental techniques. The samples were built by sputtering, an industrially scalable technique, and thus the technological implementation of these results may be economically feasible. Still, two other results consistently achieved over multiple efforts in this work give pause. The first of these results was that very specific, pristine surfaces upon which to build the nanostructures were strictly required in order to achieve measurable results. The second of these results was that compressively strained films with concomitant reductions in oxygen conductivity are much easier to obtain relative to tensile-strained films with increased conductivity.

  19. Thin-film metallic glass: an effective diffusion barrier for Se-doped AgSbTe2 thermoelectric modules

    Science.gov (United States)

    Yu, Chia-Chi; Wu, Hsin-jay; Deng, Ping-Yuan; Agne, Matthias T.; Snyder, G. Jeffrey; Chu, Jinn P.

    2017-01-01

    The thermal stability of joints in thermoelectric (TE) modules, which are degraded during interdiffusion between the TE material and the contacting metal, needs to be addressed in order to utilize TE technology for competitive, sustainable energy applications. Herein, we deposit a 200 nm-thick Zr-based thin-film metallic glass (TFMG), which acts as an effective diffusion barrier layer with low electrical contact resistivity, on a high-zT Se-doped AgSbTe2 substrate. The reaction couples structured with TFMG/TE are annealed at 673 K for 8–360 hours and analyzed by electron microscopy. No observable IMCs (intermetallic compounds) are formed at the TFMG/TE interface, suggesting the effective inhibition of atomic diffusion that may be attributed to the grain-boundary-free structure of TFMG. The minor amount of Se acts as a tracer species, and a homogeneous Se-rich region is found nearing the TFMG/TE interface, which guarantees satisfactory bonding at the joint. The diffusion of Se, which has the smallest atomic volume of all the elements from the TE substrate, is found to follow Fick’s second law. The calculated diffusivity (D) of Se in TFMG falls in the range of D~10−20–10−23(m2/s), which is 106~107 and 1012~1013 times smaller than those of Ni [10−14–10−17(m2/s)] and Cu [10−8–10−11(m2/s)] in Bi2Te3, respectively.

  20. Chemical synthesis of p-type nanocrystalline copper selenide thin films for heterojunction solar cells

    Science.gov (United States)

    Ambade, Swapnil B.; Mane, R. S.; Kale, S. S.; Sonawane, S. H.; Shaikh, Arif V.; Han, Sung-Hwan

    2006-12-01

    Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 °C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu 2- xSe phase was confirmed by XRD pattern and spherical grains of 30 ± 4 - 40 ± 4 nm in size aggregated over about 130 ± 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm 2 light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells.

  1. A re-examination of cobalt-related defects in n- and p-type silicon

    Energy Technology Data Exchange (ETDEWEB)

    Scheffler, Leopold; Kolkovsky, Vladimir; Weber, Joerg [Technische Universitaet Dresden, 01069 Dresden (Germany)

    2012-10-15

    In the present work cobalt-doped n- and p-type silicon samples were studied by means of deep level transient spectroscopy (DLTS) and Laplace-DLTS (LDLTS). We demonstrate that two dominant DLTS peaks previously assigned to a substitutional Co defect have different annealing behaviour and therefore belong to different defects. After wet chemical etching three other peaks (E90, E140 and H160) were observed in the samples. The intensity of the peaks becomes larger in the H-plasma treated samples. This together with depth profiling demonstrates that the peaks are hydrogen-related defects. The origin of the peaks will be discussed. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Low-temperature TCT characterization of heavily proton irradiated p-type magnetic Czochralski silicon detectors

    CERN Document Server

    Härkönen, J; Luukka, P; Kassamakov, I; Autioniemi, M; Tuominen, E; Sane, P; Pusa, P; Räisänen, J; Eremin, V; Verbitskaya, E; Li, Z

    2007-01-01

    n+/p−/p+ pad detectors processed at the Microelectronics Center of Helsinki University of Technology on boron-doped p-type high-resistivity magnetic Czochralski (MCz-Si) silicon substrates have been investigated by the transient current technique (TCT) measurements between 100 and 240 K. The detectors were irradiated by 9 MeV protons at the Accelerator Laboratory of University of Helsinki up to 1 MeV neutron equivalent fluence of 2×1015 n/cm2. In some of the detectors the thermal donors (TD) were introduced by intentional heat treatment at 430 °C. Hole trapping time constants and full depletion voltage values were extracted from the TCT data. We observed that hole trapping times in the order of 10 ns were found in heavily (above 1×1015 neq/cm2) irradiated samples. These detectors could be fully depleted below 500 V in the temperature range of 140–180 K.

  3. 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.

  4. Chemical synthesis of p-type nanocrystalline copper selenide thin films for heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ambade, Swapnil B. [Department of Chemical Engineering, Vishwakarma Institute of Technology, Pune 411037 (India); Mane, R.S. [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong 17, Seoul 133-791 (Korea, Republic of); Kale, S.S. [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong 17, Seoul 133-791 (Korea, Republic of); Sonawane, S.H. [Department of Chemical Engineering, Vishwakarma Institute of Technology, Pune 411037 (India); Shaikh, Arif V. [Department of Electronic Science, AKI' s Poona College of Arts, Science and Commerce, Camp, Pune 411 001 (India); Han, Sung-Hwan [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong 17, Seoul 133-791 (Korea, Republic of)]. E-mail: shhan@hanyang.ac.kr

    2006-12-15

    Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 deg. C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu{sub 2-x}Se phase was confirmed by XRD pattern and spherical grains of 30 {+-} 4 - 40 {+-} 4 nm in size aggregated over about 130 {+-} 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm{sup 2} light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells.

  5. Luminescence properties of p-type thin CdS films prepared by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Ullrich, B. [Tokyo Univ. (Japan). Dept. of Physics; Ezumi, H. [Department of Electrical Engineering, Hiroshima-Denki Institute of Technology, Hiroshima 739-03 (Japan); Keitoku, S. [Hiroshima Women`s University, Hiroshima 734 (Japan); Kobayashi, T. [Tokyo Univ. (Japan). Dept. of Physics

    1995-12-01

    Investigations of the luminescence of p-type CdS:Cu thin (less than or equal to 2 {mu}m) films on glass substrate prepared by laser ablation were performed for the first time. The dependences of the luminescence on the Cu content in the thin films were studied at 300 K with argon laser lines at 457.9 nm, 488.0 nm and 514.5 nm. It is demonstrated that the luminescence excited with the 514.5 nm line corresponds to the donor-acceptor transition. Furthermore, it is shown that the intensity of the red emission of CdS:Cu films can be efficiently bleached by Cu doping. (orig.)

  6. Analysis of carrier concentration, lifetime, and electron mobility on p-type HgCdTe

    Science.gov (United States)

    Yoo, Sang Dong; Kwack, Kae Dal

    1998-03-01

    Minority carrier transport characteristics of vacancy-doped p-type HgCdTe such as carrier concentration, lifetime, and mobility are investigated. In the calculation of the carrier concentration two acceptor levels—a donor level and a trap level—were taken into account. The acceptor levels have been described by two models—two independent singly ionized levels and a divalent level with two ionization energies. When each model was examined by calculating electron mobility as a function of temperature, the latter was found to be more accurate. Electron mobility as a function of majority carrier concentration was also presented for both n-type and p-type HgCdTe with 0.225 Cd mole fraction. Steady state electron lifetime was computed assuming the acceptor levels and the trap level would act as Schokley-Read-Hall type recombination centers. The calculated results using the divalent acceptor model were in good agreement with the experimental data.

  7. 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...

  8. 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.

  9. 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.

  10. Atomic layer deposition of undoped TiO2 exhibiting p-type conductivity.

    Science.gov (United States)

    Iancu, Andrei T; Logar, Manca; Park, Joonsuk; Prinz, Fritz B

    2015-03-11

    With prominent photocatalytic applications and widespread use in semiconductor devices, TiO2 is one of the most popular metal oxides. However, despite its popularity, it has yet to achieve its full potential due to a lack of effective methods for achieving p-type conductivity. Here, we show that undoped p-type TiO2 films can be fabricated by atomic layer deposition (ALD) and that their electrical properties can be controlled across a wide range using proper postprocessing anneals in various ambient environments. Hole mobilities larger than 400 cm(2)/(V·s) are accessible superseding the use of extrinsic doping, which generally produces orders of magnitude smaller values. Through a combination of analyses and experiments, we provide evidence that this behavior is primarily due to an excess of oxygen in the films. This discovery enables entirely new categories of TiO2 devices and applications, and unlocks the potential to improve existing ones. TiO2 homojunction diodes fabricated completely by ALD are developed as a demonstration of the utility of these techniques and shown to exhibit useful rectifying characteristics even with minimal processing refinement.

  11. Piezo-phototronic effect on electroluminescence properties of p-type GaN thin films.

    Science.gov (United States)

    Hu, Youfan; Zhang, Yan; Lin, Long; Ding, Yong; Zhu, Guang; Wang, Zhong Lin

    2012-07-11

    We present that the electroluminescence (EL) properties of Mg-doped p-type GaN thin films can be tuned by the piezo-phototronic effect via adjusting the minority carrier injection efficiency at the metal-semiconductor (M-S) interface by strain induced polarization charges. The device is a metal-semiconductor-metal structure of indium tin oxide (ITO)-GaN-ITO. Under different straining conditions, the changing trend of the transport properties of GaN films can be divided into two types, corresponding to the different c-axis orientations of the films. An extreme value was observed for the integral EL intensity under certain applied strain due to the adjusted minority carrier injection efficiency by piezoelectric charges introduced at the M-S interface. The external quantum efficiency of the blue EL at 430 nm was changed by 5.84% under different straining conditions, which is 1 order of magnitude larger than the change of the green peak at 540 nm. The results indicate that the piezo-phototronic effect has a larger impact on the shallow acceptor states related EL process than on the one related to the deep acceptor states in p-type GaN films. This study has great significance on the practical applications of GaN in optoelectronic devices under a working environment where mechanical deformation is unavoidable such as for flexible/printable light emitting diodes.

  12. High power dissipative soliton in an Erbium-doped fiber laser mode-locked with a high modulation depth saturable absorber mirror.

    Science.gov (United States)

    Cabasse, A; Martel, G; Oudar, J L

    2009-06-08

    We report on a passively mode-locked erbium-doped fiber laser, using a high nonlinear modulation depth saturable absorber mirror, in a Fabry-Perot cavity. A segment of dispersion compensation fiber is added inside the cavity in order to build a high-positive dispersion regime. The setup produced highly chirped pulses with an energy of 1.8 nJ at a repetition rate of 33.5 MHz. Numerical simulations accurately reflect our experimental results and show that pulse-shaping in this laser could be interpreted as producing 'dissipative solitons'.

  13. About the Nature of Electroluminescence Centers in Plastically Deformed Crystals of p-type Silicon

    Directory of Open Access Journals (Sweden)

    B.V. Pavlyk

    2015-10-01

    Full Text Available The paper describes research of dislocation electroluminescence of single crystal p-type silicon with a high concentration of dislocations on the surface (111. It is shown the reaction of the luminescence spectra and capacitive-modulation spectra of samples after high-temperature annealing in an atmosphere of flowing oxygen. The analysis of the results lets us to establish the nature of recombination centers and their reorganization under high-temperature annealing. It is shown that deposition of Al film on the substrate p-Si leads to the formation of strain capacity and the localization of defects in the surface layer that corresponds to luminescence centers.

  14. 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...

  15. Novel electro-optical phase modulator based on GaInAs/InP modulation-doped quantum-well structures

    DEFF Research Database (Denmark)

    Thirstrup, C.

    1992-01-01

    A novel electro-optical phase modulator working at 1.55 µm is analyzed and proposed. It is shown by a numerical model that in a GaInAs/InP pn-nin-pn multiple-quantum-well waveguide structure, large optical phase modulation can be obtained at small intensity modulation and with improved performance...... compared to what is achieved in quantum confined Stark effect modulators of the same material system. The device proposed is based on a modulation of the quasi-Fermi energies of the electrons in the GaInAs quantum wells. This operational principle allows GHz modulation frequencies. Applied Physics Letters...

  16. Preparation of p-type NiO films by reactive sputtering and their application to CdTe solar cells

    Science.gov (United States)

    Ishikawa, Ryousuke; Furuya, Yasuaki; Araki, Ryouichi; Nomoto, Takahiro; Ogawa, Yohei; Hosono, Aikyo; Okamoto, Tamotsu; Tsuboi, Nozomu

    2016-02-01

    Transparent p-type NiO films were prepared by reactive sputtering using the facing-target system under Ar-diluted O2 gas at Tsub of 30 and 200 °C. The increasing intensity of dominant X-ray diffraction (XRD) peaks indicates improvements in the crystallinity of NiO films upon Cu doping. In spite of the crystallographic and optical changes after Cu-doping, the electrical properties of Cu-doped NiO films were slightly improved. Upon Ag-doping at 30 °C under low O2 concentration, on the other hand, the intensity of the dominant (111) XRD peaks was suppressed and p-type conductivity increased from ˜10-3 to ˜10-1 S cm-1. Finally, our Ag-doped NiO films were applied as the back contact of CdTe solar cells. CdTe solar cells with a glass/ITO/CdS/CdTe/NiO structure exhibited an efficiency of 6.4%, suggesting the high potential of using p-type NiO for the back-contact film in thin-film solar cells.

  17. Synthesis and Electronic Transport of Hydrothermally Synthesized p-Type Na-Doped SnSe

    Science.gov (United States)

    Yang, Zong-Ren; Chen, Wei-Hao; Liu, Chia-Jyi

    2016-11-01

    A series of polycrystalline Sn1-x Na x Se with x = 0.00, 0.02, 0.04 and 0.10 were fabricated using hydrothermal synthesis followed by evacuated-and-encapsulated sintering. The as-fabricated materials were characterized using powder x-ray diffraction and electronic transport. The resulting materials were single phase. Partial replacement of Na for Sn leads to a simultaneous increase of electrical conductivity and thermopower. The x = 0.04 sample has the largest power factor among the series of the samples. Upon partial replacement of Na for Sn, the power factor is significantly enhanced as compared to the undoped SnSe. The maximum ZT value of ˜0.4 was achieved for Sn0.96Na0.04Se at 550 K.

  18. Characterization of the Microstructure of HgCdTe with p-Type Doping

    Science.gov (United States)

    Lobre, C.; Jouneau, P.-H.; Mollard, L.; Ballet, P.

    2014-08-01

    Nitrogen, phosphorus, arsenic, and antimony ions were implanted in Hg0.3Cd0.7Te (MCT) layers under the same implantation conditions. An identical annealing process was then applied to these layers to eradicate implantation damage and to activate the impurities. Implantation damage was investigated by direct visualization, by use of bright-field scanning transmission electron microscopy (BF-STEM). Secondary-ion mass spectrometry was used to investigate impurity diffusion on annealing. The combination of these two techniques revealed the significant effect of structural implantation damage on the diffusion process. Annealed layers were then investigated by high-resolution STEM imaging and energy-dispersive x-ray spectroscopy in STEM (STEM-EDX). This approach enables direct visualization and, therefore, further description of arsenic and antimony-rich nanocrystals.

  19. Analysis of nonlinear optical and dynamic gain effects of moderate-power, pulse-position-modulated, erbium-doped fiber amplifiers for deep-space applications.

    Science.gov (United States)

    Yao, Haomin; Wright, Malcolm W; Marciante, John R

    2014-09-20

    Lasers for use in deep-space applications such as interplanetary optical communications employ multiwatt resonantly pumped dual-clad erbium-doped fiber amplifiers and the pulse-position modulation scheme. Nonlinear optical effects and dynamic gain effects often impair their performance and limit their operational range. These effects are analyzed theoretically and numerically with a time-dependent two-level propagation model, respectively. Self-phase modulation and stimulated Raman scattering are found to limit the usable data format space. In operational regimes free from nonlinear effects, dynamic gain effects such as the variation in the output pulse energy and square-pulse distortion are quantified. Both are found to primarily depend on the symbol duration and can be as large as 28% and 21%, respectively.

  20. P-type conductivity in annealed strontium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Poole, Violet M.; Corolewski, Caleb D.; McCluskey, Matthew D., E-mail: mattmcc@wsu.edu [Department of Physics and Astronomy, Washington State University, Pullman, WA 99164-2814 (United States)

    2015-12-15

    Hall-effect measurements indicate p-type conductivity in bulk, single-crystal strontium titanate (SrTiO{sub 3}, or STO) samples that were annealed at 1200°C. Room-temperature mobilities above 100 cm{sup 2}/V s were measured, an order of magnitude higher than those for electrons (5-10 cm{sup 2}/V s). Average hole densities were in the 10{sup 9}-10{sup 10} cm{sup −3} range, consistent with a deep acceptor.

  1. Characterization of equine urinary metabolites of selective androgen receptor modulators (SARMs) S1, S4 and S22 for doping control purposes.

    Science.gov (United States)

    Hansson, Annelie; Knych, Heather; Stanley, Scott; Thevis, Mario; Bondesson, Ulf; Hedeland, Mikael

    2015-08-01

    Selective androgen receptor modulators, SARMs, constitute a class of compounds with anabolic properties but with few androgenic side-effects. This makes them possible substances of abuse and the World Anti-Doping Agency (WADA) has banned the entire class of substances. There have been several cases of illicit use of aryl propionamide SARMs in human sports and in 2013, 13 cases were reported. These substances have been found to be extensively metabolized in humans, making detection of metabolites necessary for doping control. SARMs are also of great interest to equine doping control, but the in vivo metabolite pattern and thus possible analytical targets have not been previously studied in this species. In this study, the urinary metabolites of the SARMs S1, S4, and S22 in horses were studied after intravenous injection, using ultra high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC-QToF-MS). Eight different metabolites were found for SARM S1, nine for SARM S4, and seven for SARM S22. The equine urinary metabolite profiles differed significantly from those of humans. The parent compounds were only detected for SARMs S4 and S22 and only at the first sampling time point at 3 h post administration, making them unsuitable as target compounds. For all three SARMs tested, the metabolite yielding the highest response had undergone amide hydrolysis, hydroxylation and sulfonation. The resulting phase II metabolites (4-nitro-3-trifluoro-methyl-phenylamine sulfate for SARMs S1 and S4 and 4-cyano-3-trifluoro-methyl-phenylamine sulfate for SARM S22) are proposed as analytical targets for use in equine doping control.

  2. Identification of selected in vitro generated phase-I metabolites of the steroidal selective androgen receptor modulator MK-0773 for doping control purposes.

    Science.gov (United States)

    Lagojda, Andreas; Kuehne, Dirk; Krug, Oliver; Thomas, Andreas; Wigger, Tina; Karst, Uwe; Schänzer, Wilhelm; Thevis, Mario

    2016-01-01

    Research into developing anabolic agents for various therapeutic purposes has been pursued for decades. As the clinical utility of anabolic-androgenic steroids has been found to be limited because of their lack of tissue selectivity and associated off-target effects, alternative drug entities have been designed and are commonly referred to as selective androgen receptor modulators (SARMs). While most of these SARMs are of nonsteroidal structure, the drug candidate MK-0773 comprises a 4-aza-steroidal nucleus. Besides the intended therapeutic use, SARMs have been found to be illicitly distributed and misused as doping agents in sport, necessitating frequently updated doping control analytical assays. As steroidal compounds reportedly undergo considerable metabolic transformations, the phase-I metabolism of MK-0773 was simulated using human liver microsomal (HLM) preparations and electrochemical conversion. Subsequently, major metabolic products were identified and characterized employing liquid chromatography-high-resolution/high- accuracy tandem mass spectrometry with electrospray (ESI) and atmospheric pressure chemical ionization (APCI) as well as nuclear magnetic resonance (NMR) spectroscopy. MK-0773 produced numerous phase-I metabolites under the chosen in vitro incubation reactions, mostly resulting from mono- and bisoxygenation of the steroid. HLM yielded at least 10 monooxygenated species, while electrochemistry-based experiments resulted predominantly in three monohydroxylated metabolites. Elemental composition data and product ion mass spectra were generated for these analytes, ESI/APCI measurements corroborated the formation of at least two N-oxygenated metabolites, and NMR data obtained from electrochemistry-derived products supported structures suggested for three monohydroxylated compounds. Hereby, the hydroxylation of the A-ring located N- bound methyl group was found to be of particular intensity. In the absence of controlled elimination studies, the

  3. Metal Fluoride Inhibition of a P-type H+ Pump

    Science.gov (United States)

    Pedersen, Jesper Torbøl; Falhof, Janus; Ekberg, Kira; Buch-Pedersen, Morten Jeppe; Palmgren, Michael

    2015-01-01

    The plasma membrane H+-ATPase is a P-type ATPase responsible for establishing electrochemical gradients across the plasma membrane in fungi and plants. This essential proton pump exists in two activity states: an autoinhibited basal state with a low turnover rate and a low H+/ATP coupling ratio and an activated state in which ATP hydrolysis is tightly coupled to proton transport. Here we characterize metal fluorides as inhibitors of the fungal enzyme in both states. In contrast to findings for other P-type ATPases, inhibition of the plasma membrane H+-ATPase by metal fluorides was partly reversible, and the stability of the inhibition varied with the activation state. Thus, the stability of the ATPase inhibitor complex decreased significantly when the pump transitioned from the activated to the basal state, particularly when using beryllium fluoride, which mimics the bound phosphate in the E2P conformational state. Taken together, our results indicate that the phosphate bond of the phosphoenzyme intermediate of H+-ATPases is labile in the basal state, which may provide an explanation for the low H+/ATP coupling ratio of these pumps in the basal state. PMID:26134563

  4. P-type polymer-based Ag2S atomic switch for “tug of war” operation

    Science.gov (United States)

    Lutz, Carolin; Hasegawa, Tsuyoshi; Tsuchiya, Takashi; Adelsberger, Christoph; Hayakawa, Ryoma; Chikyow, Toyohiro

    2017-06-01

    The Ag2S gap-type atomic switch based “tug of war” device is a promising element for building a new type of CMOS free neuromorphic computer-hardware. Since Ag+ cations are reduced during operation of the device, it was thought that the gap-material should be a n-type polymer. In this study, we revealed that the polymer bithiophene-oligoethyleneoxide (BTOE) doped poly(ethylene oxide) (PEO), which was used as gap-material in the first demonstration of the “tug of war”, is a p-type polymer. For this we used impedance spectroscopy and transistor measurements. We elaborate on how the electrochemical processes in the “tug of war” devices could be explained in the case of p-type conductive gap-materials.

  5. Control of p-type and n-type thermoelectric properties of bismuth telluride thin films by combinatorial sputter coating technology

    Science.gov (United States)

    Goto, Masahiro; Sasaki, Michiko; Xu, Yibin; Zhan, Tianzhuo; Isoda, Yukihiro; Shinohara, Yoshikazu

    2017-06-01

    p- and n-type bismuth telluride thin films have been synthesized by using a combinatorial sputter coating system (COSCOS). The crystal structure and crystal preferred orientation of the thin films were changed by controlling the coating condition of the radio frequency (RF) power during the sputter coating. As a result, the p- and n-type films and their dimensionless figure of merit (ZT) were optimized by the technique. The properties of the thin films such as the crystal structure, crystal preferred orientation, material composition and surface morphology were analyzed by X-ray diffraction, energy-dispersive X-ray spectroscopy and atomic force microscopy. Also, the thermoelectric properties of the Seebeck coefficient, electrical conductivity and thermal conductivity were measured. ZT for n- and p-type bismuth telluride thin films was found to be 0.27 and 0.40 at RF powers of 90 and 120 W, respectively. The proposed technology can be used to fabricate thermoelectric p-n modules of bismuth telluride without any doping process.

  6. 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.

  7. Origin of the n -type and p -type conductivity of MoS 2 monolayers on a SiO 2 substrate

    KAUST Repository

    Dolui, Kapildeb

    2013-04-02

    Ab initio density functional theory calculations are performed to study the electronic properties of a MoS2 monolayer deposited over a SiO 2 substrate in the presence of interface impurities and defects. When MoS2 is placed on a defect-free substrate, the oxide plays an insignificant role since the conduction band top and the valence band minimum of MoS2 are located approximately in the middle of the SiO2 band gap. However, if Na impurities and O dangling bonds are introduced at the SiO2 surface, these lead to localized states, which modulate the conductivity of the MoS2 monolayer from n- to p-type. Our results show that the conductive properties of MoS2 deposited on SiO 2 are mainly determined by the detailed structure of the MoS 2/SiO2 interface, and suggest that doping the substrate can represent a viable strategy for engineering MoS2-based devices. © 2013 American Physical Society.

  8. Electrical properties and surface morphology of electron beam evaporated p-type silicon thin films on polyethylene terephthalate for solar cells applications

    Energy Technology Data Exchange (ETDEWEB)

    Ang, P. C.; Ibrahim, K.; Pakhuruddin, M. Z. [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, Minden 11800 Penang (Malaysia)

    2015-04-24

    One way to realize low-cost thin film silicon (Si) solar cells fabrication is by depositing the films with high-deposition rate and manufacturing-compatible electron beam (e-beam) evaporation onto inexpensive foreign substrates such as glass or plastic. Most of the ongoing research is reported on e-beam evaporation of Si films on glass substrates to make polycrystalline solar cells but works combining both e-beam evaporation and plastic substrates are still scarce in the literature. This paper studies electrical properties and surface morphology of 1 µm electron beam evaporated Al-doped p-type silicon thin films on textured polyethylene terephthalate (PET) substrate for application as an absorber layer in solar cells. In this work, Si thin films with different doping concentrations (including an undoped reference) are prepared by e-beam evaporation. Energy dispersion X-ray (EDX) showed that the Si films are uniformly doped by Al dopant atoms. With increased Al/Si ratio, doping concentration increased while both resistivity and carrier mobility of the films showed opposite relationships. Root mean square (RMS) surface roughness increased. Overall, the Al-doped Si film with Al/Si ratio of 2% (doping concentration = 1.57×10{sup 16} atoms/cm{sup 3}) has been found to provide the optimum properties of a p-type absorber layer for fabrication of thin film Si solar cells on PET substrate.

  9. Conductance Modulation across the Metal-Insulator Transition in Single Nanowire Devices of doped-VO2 Gated with Ionic Liquid

    Science.gov (United States)

    Stabile, Adam; Whittaker, Luisa; Banerjee, Sarbajit; Sambandamurthy, G.

    2013-03-01

    Studies of the effects of charge modulation in VO2 systems may provide useful insights into the microscopic mechanisms behind its metal-insulator transition (MIT). Recently, ionic liquid (IL) has become a popular material for gating nanodevices due to its superior charge accumulation capabilities. Thus, using IL to gate single nanowires of W-doped-VO2, we systematically study the modulation of electrical transport across the temperature-driven and voltage-driven MIT as a function of gate voltage. We report the manifestation of hysteresis loops, which show an unprecedented modulation of resistance and current by as large as 20%. Moreover, we show that the largest modulation loop coincides with the largest changes in resistance across the temperature-driven MIT suggesting that the memory behavior in VO2 and its MIT are closely linked. Similar behavior is also observed across the voltage-driven MIT. These studies lay the ground work for an alternative approach to understanding the mechanisms behind the MIT in VO2 systems when driven by different external parameters.

  10. Extrinsic doping in silicon revisited

    KAUST Repository

    Schwingenschlögl, Udo

    2010-06-17

    Both n-type and p-type doping of silicon is at odds with the charge transfer predicted by Pauling electronegativities and can only be reconciled if we no longer regarding dopant species as isolated atoms but rather consider them as clusters consisting of the dopant and its four nearest neighbor silicon atoms. The process that gives rise to n-type and p-type effects is the charge redistribution that occurs between the dopant and its neighbors, as we illustrate here using electronic structure calculations. This view point is able to explain why conventional substitutional n-type doping of carbon has been so difficult.

  11. Extrinsic doping in silicon revisited

    Energy Technology Data Exchange (ETDEWEB)

    Schwingenschloegl, Udo [PSE Division, KAUST, Thuwal, Kingdom of Saudi Arabia (Saudi Arabia); Chroneos, Alexander; Grimes, Robin [Department of Materials, Imperial College London, London SW7 2BP (United Kingdom); Schuster, Cosima [Institut fuer Physik, Universitaet Augsburg, 86135 Augsburg (Germany)

    2011-07-01

    Both n-type and p-type doping of silicon is at odds with the charge transfer predicted by Pauling electronegativities and can only be reconciled if we no longer regard dopant species as isolated atoms but rather consider them as clusters consisting of the dopant and its four nearest neighbor silicon atoms. The process that gives rise to n-type and p-type effects is the charge redistribution that occurs between the dopant and its neighbors, as we illustrate here using electronic structure calculations. This view point is able to explain why conventional substitutional n-type doping of carbon has been so difficult.

  12. Growth and characterization of Czochralski-grown n and p-type GaAs for space solar cell substrates

    Science.gov (United States)

    Chen, R. T.

    1983-01-01

    Progress in LEC (liquid encapsulated Czochralski) crystal growth techniques for producing high-quality, 3-inch-diameter, n- and p-type GaAs crystals suitable for solar cell applications is described. The LEC crystals with low dislocation densities and background impurities, high electrical mobilities, good dopant uniformity, and long diffusion lengths were reproducibly grown through control of the material synthesis, growth and doping conditions. The capability for producing these large-area, high-quality substrates should positively impact the manufacturability of highly efficiency, low cost, radiation-hard GaAs solar cells.

  13. The influence of substrate and annealing temperatures on electrical properties of p-type ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, C.Y. [Department of Mathematics and Physics, Shanghai Institute of technology, 120 Cao Bao Road, Shanghai 200235 (China)], E-mail: zhang_canyun@sit.edu.cn

    2009-01-15

    In this study, p-type ZnO films with excellent electrical properties were prepared by ultrasonic spray pyrolysis (USP) combining with a N-Al codoping technique. The influence of the substrate temperature and annealing temperature on electrical properties of ZnO films was investigated. The growth and doping process of ZnO films was explored by thermogravimetry, differential scanning calorimetry and mass spectrum (TG-DSC-MS) measurements. It is suggested that the variation of electrical properties of ZnO films with the substrate temperature and annealing temperature results from the removal of H element out of the films.

  14. 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.

  15. p-Type NiO Hybrid Visible Photodetector.

    Science.gov (United States)

    Mallows, John; Planells, Miquel; Thakare, Vishal; Bhosale, Reshma; Ogale, Satishchandra; Robertson, Neil

    2015-12-23

    A novel hybrid visible-light photodetector was created using a planar p-type inorganic NiO layer in a junction with an organic electron acceptor layer. The effect of different oxygen pressures on formation of the NiO layer by pulsed laser deposition shows that higher pressure increases the charge carrier density of the film and lowers the dark current in the device. The addition of a monolayer of small molecules containing conjugated π systems and carboxyl groups at the device interface was also investigated and with correct alignment of the energy levels improves the device performance with respect to the quantum efficiency, responsivity, and photogeneration. The thickness of the organic layer was also optimized for the device, giving a responsivity of 1.54 × 10(-2) A W(-1) in 460 nm light.

  16. Elucidating Functional Aspects of P-type ATPases

    DEFF Research Database (Denmark)

    Autzen, Henriette Elisabeth

    2015-01-01

    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...... cancer and pathogenic microbes. The goal of this Ph.D. dissertation was to functionally characterize SERCA1a and CopA from Legionella pneumophila (LpCopA) through a range of different methods within structural biology. Crystallographic studies of SERCA1a led to a newly determined crystal structure......P-type ATPases are proteins that act to maintain ion homeostasis and electrochemical gradients through the translocation of cations across cell membranes. Underscoring their significance in humans, dysfunction of the ATPases can lead to crucial diseases. Dysfunction of the sarco...

  17. Study on the p-type QWIP-LED device

    Institute of Scientific and Technical Information of China (English)

    ZHEN; Honglou; XIONG; Dayuan; ZHOU; Xuchang; LI; Ning; SHAO; Jun; LU; Wei

    2006-01-01

    A p-type quantum well infrared photodetector (QWIP) integrated with a light-emitting diode (LED) (named QWIP-LED) was fabricated and studied. The infrared photo-response spectrum was obtained from the device resistance variation and the near-infrared photo-emission intensity variation. A good agreement between these two spectra was observed, which demonstrates that the long-wavelength infrared radiation around 7.5 μm has been transferred to the near-infrared light at 0.8 μm by the photo-electronic process in the QWIP-LED structure. Moreover, the experimentally observed infrared response wavelength is in good agreement with the theoretical calculation value of 7.7 μm. The results on the upconversion of the infrared radiation will be very useful for the new infrared focal plane array technology.

  18. In vitro metabolism studies on the selective androgen receptor modulator (SARM) LG121071 and its implementation into human doping controls using liquid chromatography-mass spectrometry.

    Science.gov (United States)

    Knoop, Andre; Krug, Oliver; Vincenti, Marco; Schänzer, Wilhelm; Thevis, Mario

    2015-01-01

    LG121071 is a member of the tetrahydroquinolinone-based class of selective androgen receptor modulator (SARM) drug candidates. These nonsteroidal compounds are supposed to act as full anabolic agents with reduced androgenic properties. As SARMs provide an alternative to anabolic androgenic steroids, they represent an emerging class of potential doping substances abused by athletes for illicit performance enhancement. According to the World Anti-Doping Agency's regulations, SARMs are banned substances and part of the Prohibited List since 2008. In consideration of the increasing number of adverse analytical findings in doping controls caused by SARMs abuse, potential drug candidates such as LG121071 have been proactively investigated to enable a timely integration into routine testing procedures even though clinical trials are not yet complete. In the present approach, the collision-induced dissociation (CID) of LG121071 was characterized by means of electrospray ionization-high resolution/high accuracy mass spectrometry, MS(n), and isotope labeling experiments. Interestingly, the even-electron precursor ion [M + H](+) at m/z 297 was found to produce a radical cation at m/z 268 under CID conditions, violating the even-electron rule that commonly applies. For doping control purposes, metabolites were generated in vitro and a detection method for urine samples based on liquid chromatography-tandem mass spectrometry was established. The overall metabolic conversion of LG121071 was modest, yielding primarily mono-, bis- and trishydroxylated species. Notable, however, was the identification of a glucuronic acid conjugate of the intact drug, attributed to an N-glucuronide structure. The sample preparation procedure included the enzymatic hydrolysis of glucuronides prior to liquid-liquid extraction, allowing intact LG121071 to be measured, as well as the corresponding phase-I metabolites. The method was characterized concerning inter alia lower limit of detection (0

  19. Segmented Thermoelectric Oxide-based Module

    DEFF Research Database (Denmark)

    Le, Thanh Hung; Linderoth, Søren

    -performance segmented oxide-based module comprising of 4-unicouples using segmentation of the half-Heusler Ti0.3Zr0.35Hf0.35CoSb0.8Sn0.2 and the misfit-layered cobaltite Ca3Co4O9+δ as the p-leg and 2% Al-doped ZnO as the n-leg was successfully fabricated and characterized. The results (presented in Chapter 5) show...... in the interfacial contact resistance between the n-type material (doped ZnO) and the metal electrode. The next study (Chapter 6) focuses on enhancing the efficiency of a single oxide-based segmented leg by further reducing the contact resistance and employing materials with better TE properties, i.e. a p-type leg...

  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. The effect of zinc diffusion on extinction ratio of MQW electroabsorption modulator integrated with DFB laser

    Science.gov (United States)

    Zhou, Daibing; Zhang, Ruikang; Wang, Huitao; Wang, Baojun; Bian, Jing; An, Xin; Zhao, Lingjuan; Zhu, Hongliang; Ji, Chen; Wang, Wei

    2014-11-01

    Monolithically integrated electroabsorption modulated lasers (EML) are widely being used in the optical fiber communication systems, due to their low chip, compact size and good compatible with the current communication systems. In this paper, we investigated the effect of Zinc diffusion on extinction ratio of electroabsorption modulator (EAM) integrated with distributed feedback laser (DFB). EML was fabricated by selective area growth (SAG) technology. The MQW structure of different quantum energy levels was grown on n-type InP buffer layer with 150nm thick SiO2 parallel stripes mask by selective area metal-organic chemical vapor deposition (MOCVD). A 35nm photoluminescence wavelength variation was observed between the laser area (λPL=1535nm) and modulator area (λPL=1500nm) by adjusting the dimension of parallel stripes. The grating (λ=1550nm) was fabricated in the selective area. The device was mesa ridge structure, which was constituted of the DFB laser, isolation gap and modulator. The length of every part is 300μm, 50μm, and 150μm respectively. Two samples were fabricated with the same structure and different p-type Zn-doped concentration, the extinction ratio of heavy Zn-doped device is 12.5dB at -6V. In contrast, the extinction ratio of light Zn-doped device is 20dB at -6V, that was improved for approximate 60%. The different Zn diffusion depth into the MQW absorption layer was observed by Secondary ion mass spectrometer (SIMS). The heavy Zn-doped device diffused into absorption layer deeper than the light Zn-doped device, which caused the large non-uniformity of the electric field in the MQW layer. So the extinction ratio characteristics can be improved by optimizing the Zn-doped concentration of p-type layer.

  2. Recycling of p-type mc-si Top Cuts into p-type mono c-Si Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Bronsveld, P.C.P.; Manshanden, P.; Lenzmann, F.O. [ECN Solar Energy, Westerduinweg 3, P.O. Box 1, NL-1755 ZG Petten (Netherlands); Gjerstad, O. [Si Pro Holding AS, Ornesveien 3, P.O. Box 37, 8161, Glomfjord (Norway); Oevrelid, E.J. [SINTEF, Alfred Getz Vei 2, 7465, Trondheim (Norway)

    2013-07-01

    Solar cell results and material analysis are presented of 2 p-type Czochralski (Cz) ingots pulled from a charge consisting of 100% and 50% recycled multicrystalline silicon top cuts. The top cuts were pre-cleaned with a dedicated low energy consuming technology. No structure loss was observed in the bodies of the ingots. The performance of solar cells made from the 100% recycled Si ingot decreases towards the seed end of the ingot, which could be related to a non-optimal pulling process. Solar cells from the tail end of this ingot and from the 50% recycled Si ingot demonstrated an average solar cell efficiency of 18.6%. This is only 0.1% absolute lower than the efficiency of higher resistivity reference solar cells from commercially available wafers that were co-processed.

  3. Electronic Structure of Doped Trans-Polyacetylene

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The behavior of electronic structures of doped trans-polyacetylene is revealed by a simplemethod. (C24H26)+n is used to simulate p-type doped trans-polyacetylene at various doping concentrations.The electronic structure is calculated by CNDO/2 method. These calculations show that at low doping lev-el, the decrease of electronic energy compensates the increase of elastic energy, thus the bond alternationexists, and the charge carriers are solitons. When doping level is high, the increase of elastic energy islarger than the decrease of electronic energy, the bond alternation disappears, solitons no longer exist,and polyacetylene is in a metalic state.

  4. Increased efficiency in pn-junction PbS QD solar cells via NaHS treatment of the p-type layer

    Science.gov (United States)

    Speirs, Mark J.; Balazs, Daniel M.; Dirin, Dmitry N.; Kovalenko, Maksym V.; Loi, Maria Antonietta

    2017-03-01

    Lead sulfide quantum dot (PbS QD) solar cell efficiencies have improved rapidly over the past years due in large part to intelligent band alignment considerations. A pn-junction can be formed by connecting PbS layers with contrasting ligands. However, the resulting doping concentrations are typically low and cannot be effectively controlled. Here, we present a method of chemically p-doping films of thiol capped PbS QDs. P-n junction solar cells with increased doping in the p-type layer show improved short circuit current and fill factor, leading to an improvement in the power conversion efficiency from 7.1% to 7.6%. By examining Schottky diodes, field effect transistors, and the absorption spectra of treated and untreated PbS QDs, we show that the improved efficiency is due to the increased doping concentration in the thiol capped QD layer and to denser packing of the PbS QD film.

  5. Modulating optical rectification, second and third harmonic generation of doped quantum dots: Interplay between hydrostatic pressure, temperature and noise

    Science.gov (United States)

    Ganguly, Jayanta; Saha, Surajit; Bera, Aindrila; Ghosh, Manas

    2016-10-01

    We examine the profiles of optical rectification (OR), second harmonic generation (SHG) and third harmonic generation (THG) of impurity doped QDs under the combined influence of hydrostatic pressure (HP) and temperature (T) in presence and absence of Gaussian white noise. Noise has been incorporated to the system additively and multiplicatively. In order to study the above nonlinear optical (NLO) properties the doped dot has been subjected to a polarized monochromatic electromagnetic field. Effect of application of noise is nicely reflected through alteration of peak shift (blue/red) and variation of peak height (increase/decrease) of above NLO properties as temperature and pressure are varied. All such changes again sensitively depends on mode of application (additive/multiplicative) of noise. The remarkable influence of interplay between noise strength and its mode of application on the said profiles has also been addressed. The findings illuminate fascinating role played by noise in tuning above NLO properties of doped QD system under the active presence of both hydrostatic pressure and temperature.

  6. Regulating Mid-infrared to Visible Fluorescence in Monodispersed Er3+-doped La2O2S (La2O2SO4) Nanocrystals by Phase Modulation

    Science.gov (United States)

    Pan, Qiwen; Yang, Dandan; Kang, Shiliang; Qiu, Jianrong; Dong, Guoping

    2016-11-01

    Rare earth doped mid-infrared (MIR) fluorescent sources have been widely investigated due to their various potential applications in the fields of communication, chemical detecting, medical surgery and so forth. However, with emission wavelength extended to MIR, multiphonon relaxation process that strongly quenched the MIR emission is one of the greatest challenges for such practical applications. In our design, we have described a controllable gas-aided annealing strategy to modulate the phase, crystal size, morphology and fluorescent performance of a material simultaneously. Uniform and monodispersed Er3+-doped La2O2S and La2O2SO4 nanocrystals with a similar lattice structure, crystallinity, diameter and morphology have been introduced to investigate the impact of multiphonon relaxation on luminescence performance. Detailed spectroscopic evolutions in the region of MIR, near-infrared (NIR), visible upconversion (UC) and their corresponding decay times provide insight investigation into the fluorescent mechanism caused by multiphonon relaxation. A possible energy transfer model has also been established. Our results present direct observation and mechanistic investigation of fluorescent evolution in multiphonon relaxation process, which is conductive to design MIR fluorescent materials in the future. To the best of our knowledge, it is the first investigation on MIR fluorescent performance of La2O2S nanocrystals, which may find various applications in many photoelectronic fields.

  7. Aryl-propionamide-derived selective androgen receptor modulators: liquid chromatography-tandem mass spectrometry characterization of the in vitro synthesized metabolites for doping control purposes.

    Science.gov (United States)

    Kuuranne, Tiia; Leinonen, Antti; Schänzer, Wilhelm; Kamber, Matthias; Kostiainen, Risto; Thevis, Mario

    2008-03-01

    Selective androgen receptor modulators (SARM) are a prominent group of compounds for being misused in sports owing to their advantageous anabolic properties and reduced side effects. To target the preventive doping control analysis in relevant compounds, the challenge is to predict the metabolic fate of a new compound. For aryl-propionamide-derived SARM, an in vitro assay employing microsomal and S9 human liver enzymes was developed to simulate phase-I and phase-II metabolic reactions. In vitro metabolic profiles and the structure-metabolic relationship were compared between four structurally modified substrates. Accurate mass measurements were used to characterize the synthesized metabolites, and also collision-induced dissociation was examined to suggest the methodological approach to monitor the prohibited use of aryl-propionamide-derived drug candidates. Subsequent phase-I and phase-II metabolic reactions were successfully combined in one in vitro assay. The main routes of phase-I modifications involved the hydrolysis of ether linkage, monohydroxylation, and hydrolytic cleavage of the amide bond. Nitro-reduction and deacetylation were reactions observed for substrates possessing the corresponding functionality. SARM metabolites were analyzed in negative ion electrospray ionization and detected as deprotonated species [M-H](-). The main metabolic modifications were observed to occur in the B-ring side, and collision-induced dissociation resulted in the product ions originating from the A-ring side of the compound. These structure-specific ions may be monitored as target ions in the routine doping control.

  8. (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.

  9. Infrared Transparent Spinel Films with p -Type Conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Windisch, Charles F.; Exarhos, Gregory J.; Ferris, Kim F.; Engelhard, Mark H.; Stewart, Donald C.

    2001-11-29

    Spinel oxide films containing at least two transition metal cations were found to exhibit p-type conductivity with high optical transparency from the visible to wavelengths near 15 micrometers. Resistivities as low as 0.003 ohm-cm were measured on 100 nm thick rf sputter deposited films that contained nickel and cobalt. Optical spectra, Raman scattering and XPS measurements indicated the valency of nickel localized on octahedral sites within the spinel lattice determines these properties. Electronic band structure calculations corroborated the experimental results. A resistivity minimum was found at the composition NiCo2O4 deposited from aqueous or alcoholic solutions followed by subsequent annealing at 400 degrees C in air. Solution deposited films richer in nickel than this stoichiometry always were found to phase separate into nickel oxide and a spinel phase with concomitant loss in conductivity. However, the phase stability region could be extended to higher nickel contents when rf-sputter deposition techniques were used. Sputter deposited spinel films having a nickel to cobalt ratio less than 2 were found to exhibit the highest conductivity. Results suggest that the phase stability region for these materials can be extended through appropriate choice of deposition conditions. A possible mechanism that promotes high conductivity in this system is thought to be charge transfer between the resident di- and trivalent cations that may be assisted by the magnetic nature of the oxide film.

  10. P type porous silicon resistivity and carrier transport

    Energy Technology Data Exchange (ETDEWEB)

    Ménard, S., E-mail: samuel.menard@st.com [STMicroelectronics, 10, rue Thalès de Milet, 37071 Tours Cedex 2 (France); Fèvre, A. [STMicroelectronics, 10, rue Thalès de Milet, 37071 Tours Cedex 2 (France); Université François Rabelais de Tours, CNRS, CEA, INSA CVL, GREMAN UMR 7347, Tours (France); Billoué, J.; Gautier, G. [Université François Rabelais de Tours, CNRS, CEA, INSA CVL, GREMAN UMR 7347, Tours (France)

    2015-09-14

    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{sub %}) was found to be the major contributor to the PS resistivity (ρ{sub PS}). ρ{sub PS} increases exponentially with P{sub %}. Values of ρ{sub PS} as high as 1 × 10{sup 9} Ω cm at room temperature were obtained once P{sub %} exceeds 60%. ρ{sub 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{sub PS}. Based on these results, it was also possible to deduce the carrier transport mechanisms in PS. For P{sub %} lower than 45%, the conduction occurs through band tails and deep levels in the tissue surrounding the crystallites. When P{sub %} 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.

  11. 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.

  12. Fermi-edge singularity in photoluminescence spectra of modulation-doped AlGaAs/InGaAs/GaAs quantum wells

    Indian Academy of Sciences (India)

    K Gopalakrishna Naik; K S R K Rao; T Srinivasan; R Muralidharan

    2011-12-01

    The photoluminescence study of Fermi-edge singularity (FES) in modulation-doped pseudomorphic AlGa1–As/InGa1–As/GaAs quantum well (QW) heterostructures is presented. In the above QW structures the optical transitions between = 1 and = 2 electronic subband to the = 1 heavy hole subband (11 and 21 transitions, respectively) are observed with FES appearing as a lower energy shoulder to the 21 transition. The observed FES is attributed to the Fermi wave vector in the first electronic subband under the conditions of population of the second electronic subband. The FES appears at about 10 meV below 21 transition around 4.2 K. Initially it gets stronger with increasing temperature and becomes a distinct peak at about 20 K. Further increase in temperature quenches FES and reaches the base line at around 40 K.

  13. Intrinsic Limits of Electron Mobility in Modulation-Doped AlGaN/GaN 2D Electron Gas by Phonon Scattering

    Institute of Scientific and Technical Information of China (English)

    Liang Pang

    2014-01-01

    We theoretically present the intrinsic limits to electron mobility in the modulation-doped AlGaN/GaN two-dimensional electron gas (2DEG) due to effects including acoustic deformation potential (DP) scattering, piezoelectric scattering (PE), and polar-optic phonon scattering (POP). We find that DE and PE are the more significant limiting factors at intermediate temperatures of 40 K to 250 K, while POP becomes dominant as room temperature is approached. Detailed numerical results are presented for the change of electron mobility with respect to temperature and carrier density. We conclude that these three types of phonon scattering, which are generally determined by the material properties but not the technical processing, are hard limits to the 2DEG mobility.

  14. Electroluminescence from a forward-biased Schottky barrier diode on modulation Si {delta}-doped GaAs/InGaAs/AlGaAs heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Babinski, Adam; Witczak, P.; Twardowski, A.; Baranowski, J. M.

    2001-06-18

    Electroluminescence (EL) from a forward-biased Schottky barrier diode on modulation Si {delta}-doped pseudomorphic GaAs/InGaAs/AlGaAs heterostructure with high mobility electron gas is investigated in this work. It has been found that the EL from the InGaAs quantum well can be observed at temperatures up to 90 K. The EL line shape depends on the current density, which reflects the filling of the InGaAs channel with electrons. The total integrated EL intensity depends linearly on the current density. We propose that hole diffusion from an inversion layer at the Schottky barrier is responsible for the observed optical recombination with electrons in the InGaAs quantum well. {copyright} 2001 American Institute of Physics.

  15. Magnetooptical study of Zeeman effect in Mn modulation-doped InAs/InGaAs/InAlAs quantum well structures

    Energy Technology Data Exchange (ETDEWEB)

    Terent' ev, Ya. V. [Physics Department, University of Regensburg, 93040 Regensburg (Germany); Ioffe Physical-Technical Institute, 194021 St. Petersburg (Russian Federation); Danilov, S. N.; Plank, H.; Loher, J.; Schuh, D.; Bougeard, D.; Weiss, D.; Ganichev, S. D. [Physics Department, University of Regensburg, 93040 Regensburg (Germany); Durnev, M. V.; Ivanov, S. V. [Ioffe Physical-Technical Institute, 194021 St. Petersburg (Russian Federation); Tarasenko, S. A.; Rozhansky, I. V. [Ioffe Physical-Technical Institute, 194021 St. Petersburg (Russian Federation); St. Petersburg State Polytechnic University, 195251 St. Petersburg (Russian Federation); Yakovlev, D. R. [Ioffe Physical-Technical Institute, 194021 St. Petersburg (Russian Federation); Experimentelle Physik 2, Technische Universität Dortmund, 44227 Dortmund (Germany)

    2015-09-21

    We report on a magneto-photoluminescence (PL) study of Zeeman effect in Mn modulation-doped InAs/InGaAs/InAlAs quantum wells (QW). Two PL lines corresponding to the radiative recombination of photoelectrons with free and bound-on-Mn holes have been observed. In the presence of a magnetic field applied in the Faraday geometry, both lines split into two circularly polarized components. While temperature and magnetic field dependence of the splitting are well described by the Brillouin function, providing an evidence for exchange interaction with spin polarized manganese ions, the value of the splitting exceeds by two orders of magnitude the value of the giant Zeeman splitting estimated for the average Mn density in QW obtained by the secondary ion mass spectroscopy.

  16. Photocatalytic enhancement of TiO{sub 2} by B and Zr co-doping and modulation of microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Chengxin; Gong, Yinyan, E-mail: ygong2007@gmail.com; Wu, Yitao; Liu, Jiaqi; Zhang, Zhen; Li, Can; Niu, Lengyuan, E-mail: niulengyuan@163.com

    2016-08-30

    Graphical abstract: B and Zr codoped sample was prepared by a sol–gel method, which exhibits the best photocatalytic performance on degradation of methylene blue solution under a simulated solar light source in comparison with undoped and singly doped TiO{sub 2} nanocrystals. The enhancement was tentatively attributed to: (1) The incorporation of interstitial boron dopants creates oxygen vacancies (Ov··) and reduce Ti{sup 4+} to Ti{sup 3+} to form [Ov··-Ti{sup 3+}]{sup +}, which traps the carriers and prolongs carrier lifetime; (2) Zr{sup 4+} ions replace Ti{sup 4+} ions and form impurity levels, which could improve visible light response, and (3) reduction of average crystallite size. - Highlights: • B and Zr co-doping can effectively improve the visible-light photocatalytic activity of TiO{sub 2} by more than twice. • XRD, Raman, and XPS measurements demonstrated that all the samples are anatase phase of TiO{sub 2} and Zr{sup 4+} ions replace the Ti{sup 4+} ions while the B{sup 3+} ions occupy the interstitial sites. • The incorporation of interstitial boron dopants creates oxygen vacancies (Ov··) and reduce Ti{sup 4+} to Ti{sup 3+} to form [Ov··-Ti{sup 3+}]{sup +}, which traps the carriers and prolongs carrier lifetime. • Zr{sup 4+} ions replace Ti{sup 4+} ions and form impurity levels, which could improve visible light response. • The co-doped samples are benefited from both B interstitials and Zr substitutes. - Abstract: Visible-light photodegradation test revealed that B and Zr co-doping can raise the photocatalytic ability of the undoped TiO{sub 2} by a fold. XRD crystallography and Raman phonon spectroscopy measurements suggest that the Zr{sup 4+} ions replace the Ti{sup 4+} ions while the B{sup 3+} ions occupy the interstitial sites, expanding the unit-cell volume and reducing crystallite size. The incorporation of interstitial boron dopants creates oxygen vacancies (Ov··) and reduce Ti{sup 4+} to Ti{sup 3+} to form [Ov··-Ti{sup 3

  17. 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).

  18. Fabrication of p-type SnO{sub 2} films via pulsed laser deposition method by using Sb as dopant

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Shihui [School of Electronic and Information Engineering, Tianjin University, Tianjin 300072 (China); Zhang, Weifeng [Key Laboratory of Photovoltaic Materials of Henan Province and School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Li, Linngxia, E-mail: lingxiali@126.com [School of Electronic and Information Engineering, Tianjin University, Tianjin 300072 (China); Xu, Dan; Dong, Helei; Jin, Yuxin [School of Electronic and Information Engineering, Tianjin University, Tianjin 300072 (China)

    2013-12-01

    p-Type transparent conducting antimony-doped tin oxide (ATO) thin films were successfully fabricated on quartz glass substrates by pulsed laser deposition using a 20 at.% Sb doped SnO{sub 2} ceramic target. The growth temperature was varied from 500 to 800 °C, after deposition, the thin films were rapidly annealed at 500 °C in air for 2 h. Several analytical tools such as X-ray diffraction (XRD), Hall measurements, four-point probe, field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet–visible–near infrared (UV–Vis–NIR) spectrophotometer were used to explore the causes of the changes in optoelectronic properties and surface micrographs. The Sb-doped SnO{sub 2} film prepared at 700 °C possessed the lowest resistivity of 0.87 Ω cm with a Hall mobility of 0.65 cm{sup 2} v{sup −1} s{sup −1} and hole concentration of 1.01 × 10{sup 19} cm{sup −3}, while the average transmittance is about 85% in the visible light region (400–800 nm). Furthermore, SnO{sub 2}-based p-n homojunction was fabricated by deposition of a Sb-doped p-type SnO{sub 2} layer on a Sb-doped n-type SnO{sub 2} layer.

  19. Mg dopant distribution in an AlGaN/GaN p-type superlattice assessed using atom probe tomography, TEM and SIMS

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, S E; Kappers, M J; Barnard, J S; Humphreys, C J; Oliver, R A [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke St., Cambridge, CB2 3QZ (United Kingdom); Clifton, P H; Ulfig, R M, E-mail: sb534@cam.ac.u [Imago Scientific Instruments Corporation, 5500 Nobel Drive, Madison, WI, 53711 (United States)

    2010-02-01

    P-type conducting layers are critical in GaN-based devices such as LEDs and laser diodes. Such layers are often produced by doping GaN with Mg, but the hole concentration can be enhanced using AlGaN/GaN p-type superlattices by exploiting the built-in polarisation fields. A Mg-doped AlGaN/GaN superlattice was studied using SIMS. Although the AlGaN and GaN were nominally doped to the same level, the SIMS data suggested a difference in doping density between the two materials. Atom probe tomography was then used to investigate the Mg distribution. The superlattice repeats were clearly visible, as expected and, in addition, significant Mg clustering was observed in both the GaN and AlGaN layers. There were many more Mg clusters in the AlGaN layers than the GaN layers, accounting for the difference in doping density suggested by SIMS. To evaluate the structural accuracy of the atom probe reconstruction, layer thicknesses from the atom probe were compared with STEM images. Finally, future work is proposed to investigate the Mg clusters in the TEM.

  20. Piezoresistive effect in p-type 3C-SiC at high temperatures characterized using Joule heating.

    Science.gov (United States)

    Phan, Hoang-Phuong; Dinh, Toan; Kozeki, Takahiro; Qamar, Afzaal; Namazu, Takahiro; Dimitrijev, Sima; Nguyen, Nam-Trung; Dao, Dzung Viet

    2016-06-28

    Cubic silicon carbide is a promising material for Micro Electro Mechanical Systems (MEMS) applications in harsh environ-ments and bioapplications thanks to its large band gap, chemical inertness, excellent corrosion tolerance and capability of growth on a Si substrate. This paper reports the piezoresistive effect of p-type single crystalline 3C-SiC characterized at high temperatures, using an in situ measurement method. The experimental results show that the highly doped p-type 3C-SiC possesses a relatively stable gauge factor of approximately 25 to 28 at temperatures varying from 300 K to 573 K. The in situ method proposed in this study also demonstrated that, the combination of the piezoresistive and thermoresistive effects can increase the gauge factor of p-type 3C-SiC to approximately 20% at 573 K. The increase in gauge factor based on the combination of these phenomena could enhance the sensitivity of SiC based MEMS mechanical sensors.

  1. Piezoresistive effect in p-type 3C-SiC at high temperatures characterized using Joule heating

    Science.gov (United States)

    Phan, Hoang-Phuong; Dinh, Toan; Kozeki, Takahiro; Qamar, Afzaal; Namazu, Takahiro; Dimitrijev, Sima; Nguyen, Nam-Trung; Dao, Dzung Viet

    2016-06-01

    Cubic silicon carbide is a promising material for Micro Electro Mechanical Systems (MEMS) applications in harsh environ-ments and bioapplications thanks to its large band gap, chemical inertness, excellent corrosion tolerance and capability of growth on a Si substrate. This paper reports the piezoresistive effect of p-type single crystalline 3C-SiC characterized at high temperatures, using an in situ measurement method. The experimental results show that the highly doped p-type 3C-SiC possesses a relatively stable gauge factor of approximately 25 to 28 at temperatures varying from 300 K to 573 K. The in situ method proposed in this study also demonstrated that, the combination of the piezoresistive and thermoresistive effects can increase the gauge factor of p-type 3C-SiC to approximately 20% at 573 K. The increase in gauge factor based on the combination of these phenomena could enhance the sensitivity of SiC based MEMS mechanical sensors.

  2. p-Type CuYO{sub 2} as hydrogen photocathode

    Energy Technology Data Exchange (ETDEWEB)

    Trari, M.; Bouguelia, A.; Bessekhouad, Y. [Laboratoire de Stockage et de Valorisation des Energies Renouvelables, BP 32 El-Alia 16311, Algiers (Algeria)

    2006-01-23

    A new photochemical system based on a CuYO{sub 2} dispersion in aqueous S{sup 2-} or SO{sub 3}{sup 2-} solution as hole scavengers is proposed. The delafossite CuYO{sub 2}, doped with calcium, is a low p-type semiconductor with a hole mobility of 7.3x10{sup -7}m{sup 2}V{sup -1}s{sup -1}. The band gap is 3.50eV and the transition is directly allowed. The valence band edge, located at 5.23eV below vacuum, is made up from Cu-3d type typical of delafossite oxides. The flat band potential V{sub fb} (+0.17V{sub sce}) lies below the H{sub 2}O/H{sub 2} potential permitting a spontaneous H{sub 2}-formation under band gap illumination in aqueous S{sup 2-} or SO{sub 3}{sup 2-} electrolytes. p-CuYO{sub 2} loaded with n-Cu{sub 2}O exhibited a higher performance with a H{sub 2} evolution rate of 0.4cm{sup 3}h{sup -1} in 0.1MS{sup 2-} (pH 13.4). The decrease of photoactivity over time is due to the formation of yellow polysulfides S{sub n}{sup 2-} which compete with H{sub 2}O in the reduction process. (author)

  3. High-throughput search of ternary chalcogenides for p-type transparent electrodes

    Science.gov (United States)

    Shi, Jingming; Cerqueira, Tiago F. T.; Cui, Wenwen; Nogueira, Fernando; Botti, Silvana; Marques, Miguel A. L.

    2017-01-01

    Delafossite crystals are fascinating ternary oxides that have demonstrated transparent conductivity and ambipolar doping. Here we use a high-throughput approach based on density functional theory to find delafossite and related layered phases of composition ABX2, where A and B are elements of the periodic table, and X is a chalcogen (O, S, Se, and Te). From the 15 624 compounds studied in the trigonal delafossite prototype structure, 285 are within 50 meV/atom from the convex hull of stability. These compounds are further investigated using global structural prediction methods to obtain their lowest-energy crystal structure. We find 79 systems not present in the materials project database that are thermodynamically stable and crystallize in the delafossite or in closely related structures. These novel phases are then characterized by calculating their band gaps and hole effective masses. This characterization unveils a large diversity of properties, ranging from normal metals, magnetic metals, and some candidate compounds for p-type transparent electrodes. PMID:28266587

  4. High-throughput search of ternary chalcogenides for p-type transparent electrodes

    Science.gov (United States)

    Shi, Jingming; Cerqueira, Tiago F. T.; Cui, Wenwen; Nogueira, Fernando; Botti, Silvana; Marques, Miguel A. L.

    2017-03-01

    Delafossite crystals are fascinating ternary oxides that have demonstrated transparent conductivity and ambipolar doping. Here we use a high-throughput approach based on density functional theory to find delafossite and related layered phases of composition ABX2, where A and B are elements of the periodic table, and X is a chalcogen (O, S, Se, and Te). From the 15 624 compounds studied in the trigonal delafossite prototype structure, 285 are within 50 meV/atom from the convex hull of stability. These compounds are further investigated using global structural prediction methods to obtain their lowest-energy crystal structure. We find 79 systems not present in the materials project database that are thermodynamically stable and crystallize in the delafossite or in closely related structures. These novel phases are then characterized by calculating their band gaps and hole effective masses. This characterization unveils a large diversity of properties, ranging from normal metals, magnetic metals, and some candidate compounds for p-type transparent electrodes.

  5. Noise-modulated self-polarization effect of impurity doped quantum dots under simultaneous presence of hydrostatic pressure and temperature

    Science.gov (United States)

    Bera, Aindrila; Ghosh, Manas

    2017-10-01

    We explore the profiles of self-polarization effect (SPE) of doped GaAs QD under simultaneous presence of hydrostatic pressure (HP), temperature and in presence of noise. Noise term carries Gaussian white character and it has been administered to the system via two different pathways; additive and multiplicative. Profiles of SPE have been monitored as a function of HP, temperature and noise strength. Under a given condition of HP and temperature, noise marks its prominent signature on the SPE profile. However, the extent to which noise affects the SPE profile visibly depends on the noise strength and the pathway through which noise is introduced. As interesting observations we have found that SPE exhibits minimization at a pressure of ∼ 170 kbar in absence of noise and at ∼ 150 kbar when noise is present. Furthermore, in presence of multiplicative noise SPE exhibits a very faint decrease with increase in T up to T ∼ 420 K. However, beyond T ∼ 420 K, further increase in temperature causes abrupt fall of SPE in a highly sharp way. The findings highlight viable ways of tuning SPE of doped QD system through subtle interplay between HP, temperature and noise.

  6. Modulation of electrical and optical properties of gallium-doped ZnO films by radio frequency magnetron sputtering

    Institute of Scientific and Technical Information of China (English)

    Liang Shuang; Mei Zeng-Xia; Du Xiao-Long

    2012-01-01

    Ga-doped ZnO (GZO) films are prepared on amorphous glass substrates at room temperature by radio frequency magnetron sputtering.The results reveal that the gallium doping efficiency,which will have an important influence on the electrical and optical properties of the film,can be governed greatly by the deposition pressure and film thickness.The position shifts of the ZnO (002) peaks in X-ray diffraction (XRD) measurements and the varied Hall mobility and carrier concentration confirms this result.The low Hall mobility is attributed to the grain boundary barrier scattering.The estimated height of barrier decreases with the increase of carrier concentration,and the trapping state density is nearly constant.According to defect formation energies and relevant chemical reactions,the photoluminescence (PL)peaks at 2.46 eV and 3.07 eV are attributed to oxygen vacancies and zinc vacancies,respectively.The substitution of more Ga atoms for Zn vacancies with the increase in film thickness is also confirmed by the PL spectrum.The obvious blueshift of the optical bandgap with an increase of carrier concentration is explained well by the Burstein-Moss (BM)effect.The bandgap difference between 3.18 eV and 3.37 eV,about 0.2 eV,is attributed to the metal-semiconductor transition.

  7. Very low surface recombination velocity on p-type c-Si by high-rate plasma-deposited aluminum oxide

    Science.gov (United States)

    Saint-Cast, Pierre; Kania, Daniel; Hofmann, Marc; Benick, Jan; Rentsch, Jochen; Preu, Ralf

    2009-10-01

    Aluminum oxide layers can provide excellent passivation for lowly and highly doped p-type silicon surfaces. Fixed negative charges induce an accumulation layer at the p-type silicon interface, resulting in very effective field-effect passivation. This paper presents highly negatively charged (Qox=-2.1×1012 cm-2) aluminum oxide layers produced using an inline plasma-enhanced chemical vapor deposition system, leading to very low effective recombination velocities (˜10 cm s-1) on low-resistivity p-type substrates. A minimum static deposition rate (100 nm min-1) at least one order of magnitude higher than atomic layer deposition was achieved on a large carrier surfaces (˜1 m2) without significantly reducing the resultant passivation quality.

  8. Versatile and Tunable Transparent Conducting Electrodes Based on Doped Graphene

    KAUST Repository

    Mansour, Ahmed E.

    2016-11-25

    The continued growth of the optoelectronics industry and the emergence of wearable and flexible electronics will continue to place an ever increasing pressure on replacing ITO, the most widely used transparent conducting electrode (TCE). Among the various candidates, graphene shows the highest optical transmittance in addition to promising electrical transport properties. The currently available large-scale synthesis routes of graphene result in polycrystalline samples rife with grain boundaries and other defects which limit its transport properties. Chemical doping of graphene is a viable route towards increasing its conductivity and tuning its work function. However, dopants are typically present at the surface of the graphene sheet, making them highly susceptible to degradation in environmental conditions. Few-layers graphene (FLG) is a more resilient form of graphene exhibiting higher conductivity and performance stability under stretching and bending as contrasted to single-layer graphene. In addition FLG presents the advantage of being amenable bulk doping by intercalation. Herein, we explore non-covalent doping routes of CVD FLG, such as surface doping, intercalation and combination thereof, through in-depth and systematic characterization of the electrical transport properties and energy levels shifts. The intercalation of FLG with Br2 and FeCl3 is demonstrated, showing the highest improvements of the figure of merit of TCEs of any doping scheme, which results from up to a five-fold increase in conductivity while maintaining the transmittance within 3% of that for the pristine value. Importantly the intercalation yields TCEs that are air-stable, due to encapsulation of the intercalant in the bulk of FLG. Surface doping with novel solution-processed metal-organic molecular species (n- and p-type) is demonstrated with an unprecedented range of work function modulation, resulting from electron transfer and the formation of molecular surface dipoles. However

  9. The use of doping spikes in GaN Gunn diodes

    Science.gov (United States)

    Macpherson, R. F.; Dunn, G. M.

    2008-08-01

    The possibility of circumventing the difficulties of fine doping control in GaN Gunn diode devices by the substitution of a fully depleted p-type doping spike for the doping notch used to promote domain formation is explored using a Monte Carlo model. The p-type doping spike is a commonly used structure, but its potential use in GaN has not been previously evaluated. The results for a functional doping spike are compared, favorably, to those for a physically reasonable doping notch.

  10. Boron doping a semiconductor particle

    Science.gov (United States)

    Stevens, Gary Don; Reynolds, Jeffrey Scott; Brown, Louanne Kay

    1998-06-09

    A method (10,30) of boron doping a semiconductor particle using boric acid to obtain a p-type doped particle. Either silicon spheres or silicon powder is mixed with a diluted solution of boric acid having a predetermined concentration. The spheres are dried (16), with the boron film then being driven (18) into the sphere. A melt procedure mixes the driven boron uniformly throughout the sphere. In the case of silicon powder, the powder is metered out (38) into piles and melted/fused (40) with an optical furnace. Both processes obtain a p-type doped silicon sphere with desired resistivity. Boric acid is not a restricted chemical, is inexpensive, and does not pose any special shipping, handling, or disposal requirements.

  11. Performance tradeoff between lateral and interdigitated doping patterns for high speed carrier-depletion based silicon modulators.

    Science.gov (United States)

    Yu, Hui; Pantouvaki, Marianna; Van Campenhout, Joris; Korn, Dietmar; Komorowska, Katarzyna; Dumon, Pieter; Li, Yanlu; Verheyen, Peter; Absil, Philippe; Alloatti, Luca; Hillerkuss, David; Leuthold, Juerg; Baets, Roel; Bogaerts, Wim

    2012-06-04

    Carrier-depletion based silicon modulators with lateral and interdigitated PN junctions are compared systematically on the same fabrication platform. The interdigitated diode is shown to outperform the lateral diode in achieving a low VπLπ of 0.62 V∙cm with comparable propagation loss at the expense of a higher depletion capacitance. The low VπLπ of the interdigitated PN junction is employed to demonstrate 10 Gbit/s modulation with 7.5 dB extinction ration from a 500 µm long device whose static insertion loss is 2.8 dB. In addition, up to 40 Gbit/s modulation is demonstrated for a 3 mm long device comprising a lateral diode and a co-designed traveling wave electrode.

  12. Dynamic characteristics of undoped and p-doped Fabry-Perot InAs/InP quantum dash based ridge waveguide lasers for access/metro networks

    Energy Technology Data Exchange (ETDEWEB)

    Mollet, O., E-mail: oriane.mollet@lpn.cnrs.fr; Martinez, A.; Merghem, K.; Ramdane, A. [CNRS, Laboratory for Photonics and Nanostructures, Route de Nozay, 91460 Marcoussis (France); Joshi, S.; Provost, J.-G.; Lelarge, F. [III-V Lab, A Joint Laboratory of Alcatel Lucent Bell Laboratories, Thales Research and Technology and CEA-LETI, Route de Nozay, 91460 Marcoussis (France)

    2014-10-06

    In this paper, we report the characteristics of InAs/InP quantum dashes (QDash) based lasers emitting around 1.55 μm. An unprecedented high modal gain of ∼100 cm{sup −1} is obtained for an optimized active structure by stacking 12 QDash layers. Directly modulated lasers allowed achieving a modulation bandwidth of ∼10 GHz and a Henry factor around 5. Thanks to p-type doping, the Henry factor value is reduced down to 2.7 while the modulation bandwidth still amounts to ∼10 GHz. This shows that doping of the active region is important to improve the dynamic characteristics of QDash lasers.

  13. Ultrafast pulse generation from erbium-doped fiber laser modulated by hybrid organic-inorganic halide perovskites

    Science.gov (United States)

    Jiang, Guobao; Miao, Lili; Yi, Jun; Huang, Bin; Peng, Wei; Zou, Yanhong; Huang, Huihui; Hu, Wei; Zhao, Chujun; Wen, Shuangchun

    2017-04-01

    We report the nonlinear optical responses of organic-inorganic halide perovskite CH3NH3PbI3 and its application in ultrafast pulse generation from an erbium-doped fiber laser in the optical communication band. By adopting the Z-scan technique, the third-order nonlinear optical responses of the organic-inorganic halide perovskites have been characterized. An ultrafast optical pulse with a pulse width of 661 fs centered at a wavelength of 1555 nm has been delivered via the nonlinear optical material introduced into the fiber laser cavity. Our experimental results confirm that the organic-inorganic halide perovskite possesses obvious third-order nonlinear optical responses in the C-band window and manifests its application potential in nonlinear optoelectronic devices.

  14. Effective masses of Quasi-2D electrons in InGaAs/GaAsSb modulation-doped heterostructures

    Science.gov (United States)

    Tanveer, Imtiaz; McCombe, Bruce; Detz, Hermann; Strasser, Gottfried

    2015-03-01

    The electronic properties of In0.53Ga0.47As/GaAs0.51Sb0.49 2D electron gas (2DEG) systems, in spite of their use in high power electronics, have not been extensively investigated. Recently, they have been suggested as potential materials for IR quantum devices such as quantum cascade lasers (QCL), and they also show a strong Rashba effect1,2. Here accurate values of the effective masses are important. Two remotely donor (Si)-doped samples grown by MBE with a 2DEG at the single heterostructure interface were studied by FIR magneto-transmission spectroscopy with a BOMEM FTIR spectrometer. The maximum mobilities (near 70 K) are 43,000 cm2/Vs and 36,000 cm2/Vs with corresponding carrier densities of 1.07 x 1012 cm-2 and 2.13 x 1012 cm-2, respectively. Cyclotron resonance measurements between 4T and 9T yielded m* = 0.0495m0 for the more heavily doped sample. Individual transmission profiles in this case showed broadening toward high-energy, which may be due to contributions to the overall absorption profile from higher occupied subbands. The lower density sample shows an energy vs B dependence that does not extrapolate to zero at B = 0. The origin of this behavior will be discussed. Work at UB supported in part by NSF DMR #1305770 and the Office of the Provost and at the TU Wien by the Austrian Science Fund (FWF): P26100-N27 (H2N) and F4909-N23 (NextLite).

  15. Facile Doping and Work-Function Modification of Few-Layer Graphene Using Molecular Oxidants and Reductants

    KAUST Repository

    Mansour, Ahmed

    2017-01-03

    Doping of graphene is a viable route toward enhancing its electrical conductivity and modulating its work function for a wide range of technological applications. In this work, the authors demonstrate facile, solution-based, noncovalent surface doping of few-layer graphene (FLG) using a series of molecular metal-organic and organic species of varying n- and p-type doping strengths. In doing so, the authors tune the electronic, optical, and transport properties of FLG. The authors modulate the work function of graphene over a range of 2.4 eV (from 2.9 to 5.3 eV)-unprecedented for solution-based doping-via surface electron transfer. A substantial improvement of the conductivity of FLG is attributed to increasing carrier density, slightly offset by a minor reduction of mobility via Coulomb scattering. The mobility of single layer graphene has been reported to decrease significantly more via similar surface doping than FLG, which has the ability to screen buried layers. The dopant dosage influences the properties of FLG and reveals an optimal window of dopant coverage for the best transport properties, wherein dopant molecules aggregate into small and isolated clusters on the surface of FLG. This study shows how soluble molecular dopants can easily and effectively tune the work function and improve the optoelectronic properties of graphene.

  16. Thermal conversion of electronic and electrical properties of AuCl3-doped single-walled carbon nanotubes.

    Science.gov (United States)

    Yoon, Seon-Mi; Kim, Un Jeong; Benayad, Anass; Lee, Il Ha; Son, Hyungbin; Shin, Hyeon-Jin; Choi, Won Mook; Lee, Young Hee; Jin, Yong Wan; Lee, Eun-Hong; Lee, Sang Yoon; Choi, Jae-Young; Kim, Jong Min

    2011-02-22

    By using carbon-free inorganic atomic layer involving heat treatment from 150 to 300 °C, environmentally stable and permanent modulation of the electronic and electrical properties of single-walled carbon nanotubes (SWCNTs) from p-type to ambi-polar and possibly to n-type has been demonstrated. At low heat treatment temperature, a strong p-doping effect from Au(3+) ions to CNTs due to a large difference in reduction potential between them is dominant. However at higher temperature, the gold species are thermally reduced, and thermally induced CNT-Cl finally occurs by the decomposition reaction of AuCl(3). Thus, in the AuCl(3)-doped SWCNTs treated at higher temperature, the p-type doping effect is suppressed and an n-type property from CNT-Cl is thermally induced. Thermal conversion of the majority carrier type of AuCl(3)-doped SWNTs is systematically investigated by combining various optical and electrical tools.

  17. Correlation between Fe-Zn Interdiffusion Observed by Scanning Capacitance Microscopy and Device Characteristics of Electro-Absorption Modulators

    Science.gov (United States)

    Ogasawara, Matsuyuki; Iga, Ryuzo; Yamanaka, Takayuki; Kondo, Susumu; Kondo, Yasuhiro

    2003-04-01

    The advantages of scanning capacitance microscopy (SCM) in observing Fe-Zn interdiffusion of an electro-absorption (EA) modulator and the relationship between the interdiffusion and device characteristics are discussed. SCM images show that there is a Zn diffusion region, in which the semi-insulating region is converted into p-type due to Zn diffusion, on both sides of the mesa and the Zn diffusion region becomes smaller as the Fe doping concentration is reduced. By comparison, scanning electron microscopy (SEM) images captured after stain etching of EA modulators did not clearly delineate the Zn diffusion front. The influence of a ruthenium (Ru)-doped InP burying layer on the interdiffusion has also been investigated by SCM. These results indicate that in order to improve the performance of EA modulators, it is important to prevent Zn diffusion into the semi-insulating layers.

  18. Design and analysis of nanowire p-type MOSFET coaxially having silicon core and germanium peripheral channel

    Science.gov (United States)

    Yu, Eunseon; Cho, Seongjae

    2016-11-01

    In this work, a nanowire p-type metal-oxide-semiconductor field-effect transistor (PMOSFET) coaxially having a Si core and a Ge peripheral channel is designed and characterized by device simulations. Owing to the high hole mobility of Ge, the device can be utilized for high-speed CMOS integrated circuits, with the effective confinement of mobile holes in Ge by the large valence band offset between Si and Ge. Source/drain doping concentrations and the ratio between the Si core and Ge channel thicknesses are determined. On the basis of the design results, the channel length is aggressively scaled down by evaluating the primary DC parameters in order to confirm device scalability and low-power applicability in sub-10-nm technology nodes.

  19. Borazino-Doped Polyphenylenes.

    Science.gov (United States)

    Marinelli, Davide; Fasano, Francesco; Najjari, Btissam; Demitri, Nicola; Bonifazi, Davide

    2017-04-19

    The divergent synthesis of two series of borazino-doped polyphenylenes, in which one or more aryl units are replaced by borazine rings, is reported for the first time, taking advantage of the decarbonylative [4 + 2] Diels-Alder cycloaddition reaction between ethynyl and tetraphenylcyclopentadienone derivatives. Because of the possibility of functionalizing the borazine core with different groups on the aryl substituents at the N and B atoms of the borazino core, we have prepared borazino-doped polyphenylenes featuring different doping dosages and orientations. To achieve this, two molecular modules were prepared: a core and a branching unit. Depending on the chemical natures of the central aromatic module and the reactive group, each covalent combination of the modules yields one exclusive doping pattern. By means of this approach, three- and hexa-branched hybrid polyphenylenes featuring controlled orientations and dosages of the doping B3N3 rings have been prepared. Detailed photophysical investigations showed that as the doping dosage is increased, the strong luminescent signal is progressively reduced. This suggests that the presence of the B3N3 rings engages additional deactivation pathways, possibly involving excited states with an increasing charge-separated character that are restricted in the full-carbon analogues. Notably, a strong effect of the orientational doping on the fluorescence quantum yield was observed for those hybrid polyphenylene structures featuring low doping dosages. Finally, we showed that Cu-catalyzed 1,3-dipolar cycloaddition is also chemically compatible with the BN core, further endorsing the inorganic benzene as a versatile aromatic scaffold for engineering of molecular materials with tailored and exploitable optoelectronic properties.

  20. Aptameric Recognition-Modulated Electroactivity of Poly(4-Styrenesolfonic Acid)-Doped Polyaniline Films for Single-Shot Detection of Tetrodotoxin

    Science.gov (United States)

    Fomo, Gertrude; Waryo, Tesfaye T.; Sunday, Christopher E.; Baleg, Abd A.; Baker, Priscilla G.; Iwuoha, Emmanuel I.

    2015-01-01

    The work being reported is the first electrochemical sensor for tetrodotoxin (TTX). It was developed on a glassy carbon electrodes (C) that was modified with poly(4-styrenesolfonic acid)-doped polyaniline film (PANI/PSSA). An amine-end functionalized TTX-binding aptamer, 5′-NH2-AAAAATTTCACACGGGTGCCTCGGCTGTCC-3′ (NH2-Apt), was grafted via covalent glutaraldehyde (glu) cross-linking. The resulting aptasensor (C//PANI+/PSSA-glu-NH2-Apt) was interrogated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in sodium acetate buffer (NaOAc, pH 4.8) before and after 30 min incubation in standard TTX solutions. Both CV and EIS results confirmed that the binding of the analyte to the immobilized aptamer modulated the electrochemical properties of the sensor: particularly the charge transfer resistance (Rct) of the PANI+/PSSA film, which served as a signal reporter. Based on the Rct calibration curve of the TTX aptasensor, the values of the dynamic linear range (DLR), sensitivity and limit of detection (LOD) of the sensor were determined to be 0.23–1.07 ng·mL−1 TTX, 134.88 ± 11.42 Ω·ng·mL−1 and 0.199 ng·mL−1, respectively. Further studies are being planned to improve the DLR as well as to evaluate selectivity and matrix effects in real samples. PMID:26370994

  1. Improving the radiation hardness properties of silicon detectors using oxygenated n-type and p-type silicon

    CERN Document Server

    Casse, G L; Hanlon, M

    2000-01-01

    The degradation of the electrical properties of silicon detectors exposed to 24 GeV/c protons were studied using pad diodes made from different silicon materials. Standard high-grade p-type and n-type substrates and oxygenated n-type substrates have been used. The diodes were studied in terms of reverse current (I/sub r/) and full depletion voltage (V/sub fd/) as a function of fluence. The oxygenated devices from different suppliers with a variety of starting materials and techniques, all show a consistent improvement of the degradation rate of V/sub fd/ and CCE compared to un- oxygenated substrate devices. Radiation damage of n-type detectors introduces stable defects acting as effective p-type doping and leads to the change of the conductivity type of the silicon bulk (type inversion) at a neutron equivalent fluence of a few 10/sup 13/ cm/sup -2/. The diode junction after inversion migrates from the original side to the back plane of the detector. The migration of the junction is avoided using silicon detec...

  2. Perovskite LaRhO{sub 3} as a p-type active layer in oxide photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Masao, E-mail: masao.nakamura@riken.jp; Krockenberger, Yoshiharu [RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan); Fujioka, Jun [Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan); Kawasaki, Masashi; Tokura, Yoshinori [RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan); Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan)

    2015-02-16

    Perovskite-type transition-metal oxides have a wide variety of physical properties and triggered intensive research on functional devices in the form of heteroepitaxial junctions. However, there is a missing component that is a p-type conventional band semiconductor. LaRhO{sub 3} (LRO) is one of very few promising candidates having its bandgap between filled t{sub 2g} and empty e{sub g} of Rh in low-spin state, but there has been no report on the synthesis of large-size single crystals or thin films. Here, we report on the junction properties of single-crystalline thin films of LRO grown on (110) oriented Nb-doped SrTiO{sub 3} substrates. The external quantum efficiency of the photo-electron conversion exceeds 1% in the visible-light region due to the wide depletion layer and long diffusion length of minority carriers in LRO. Clear indication of p-type band semiconducting character in a perovskite oxide of LRO will pave a way to explore oxide electronics of perovskite heterostructures.

  3. Novel p-Type Conductive Semiconductor Nanocrystalline Film as the Back Electrode for High-Performance Thin Film Solar Cells.

    Science.gov (United States)

    Zhang, Ming-Jian; Lin, Qinxian; Yang, Xiaoyang; Mei, Zongwei; Liang, Jun; Lin, Yuan; Pan, Feng

    2016-02-10

    Thin film solar cells, due to the low cost, high efficiency, long-term stability, and consumer applications, have been widely applied for harvesting green energy. All of these thin film solar cells generally adopt various metal thin films as the back electrode, like Mo, Au, Ni, Ag, Al, graphite, and so forth. When they contact with p-type layer, it always produces a Schottky contact with a high contact potential barrier, which greatly affects the cell performance. In this work, we report for the first time to find an appropriate p-type conductive semiconductor film, digenite Cu9S5 nanocrystalline film, as the back electrode for CdTe solar cells as the model device. Its low sheet resistance (16.6 Ω/sq) could compare to that of the commercial TCO films (6-30 Ω/sq), like FTO, ITO, and AZO. Different from the traditonal metal back electrode, it produces a successive gradient-doping region by the controllable Cu diffusion, which greatly reduces the contact potential barrier. Remarkably, it achieved a comparable power conversion efficiency (PCE, 11.3%) with the traditional metal back electrode (Cu/Au thin films, 11.4%) in CdTe cells and a higher PCE (13.8%) with the help of the Au assistant film. We believe it could also act as the back electrode for other thin film solar cells (α-Si, CuInS2, CIGSe, CZTS, etc.), for their performance improvement.

  4. Magnetotransport, structural and optical characterization of p-type modulation doped heterostructures with high Ge content Si sub 1 sub - sub x Ge sub x channel grown by SS-MBE on Si sub 1 sub - sub y Ge sub y /Si(001) virtual substrates

    CERN Document Server

    Myronov, M

    2001-01-01

    sub 4 Ge sub 0 sub . sub 6 linearly graded VS and corresponds to 14855cm sup 2 centre dot V sup - sup 1 centre dot s sup - sup 1 (2.87 centre dot 10 sup 1 sup 2 cm sup - sup 2). The highest Hall mobility (at sheet carrier density) measured at 293K was observed for Si sub 0 sub . sub 2 Ge sub 0 sub . sub 8 /Si sub 0 sub . sub 6 sub 5 Ge sub 0 sub . sub 3 sub 5 heterostructure after FTA at 750C for 30min and corresponds to 1776cm sup 2 centre dot V sup - sup 1 centre dot s sup - sup 1 (2.37 centre dot 10 sup 1 sup 3 cm sup - sup 2). To extract the drift mobility and sheet carrier density of 2DHG at temperatures up to 300K, magnetotransport measurements in magnetic fields up to 11T were performed on several heterostructures. The data were analyzed by technique of Maximum-Entropy Mobility Spectrum Analysis. The highest drift mobility (at sheet carrier density) of 2DHG at 290K was obtained for the Si sub 0 sub . sub 2 Ge sub 0 sub . sub 8 /Si sub 0 sub . sub 6 sub 5 Ge sub 0 sub . sub 3 sub 5 heterostructure after...

  5. Mass spectrometric characterization of urinary metabolites of the selective androgen receptor modulator S-22 to identify potential targets for routine doping controls.

    Science.gov (United States)

    Thevis, Mario; Thomas, Andreas; Möller, Ines; Geyer, Hans; Dalton, James T; Schänzer, Wilhelm

    2011-08-15

    Drugs that promote anabolic processes with limited undesirable effects are of considerable therapeutic interest; some notable examples include those for the treatment of cancer cachexia and muscle-wasting diseases. Anabolic properties are not only therapeutically beneficial to critically ill and debilitated patients, but are also desirable to athletes seeking artificial enhancements in endurance, strength and accelerated recovery. The use of anabolic agents in the clinical setting is being reconsidered with the emergence of a new class of drugs referred to as SARMs (selective androgen receptor modulators). SARMs have the potential to complement or even replace anabolic androgenic steroidal use with the benefit of a reduction of the undesirable side effects associated with steroid administration alone. Arylpropionamide-based SARMs such as andarine (S-4) and S-22 have shown promising therapeutic properties and have attracted the interest of elite and amateur athletes despite the absence of clinical approval, and evidence for trafficking and misuse in sport has been obtained by doping control authorities. In this communication, the elucidation of urinary metabolites of the SARM drug candidate S-22 is compared with earlier in vitro metabolism studies. Following oral administration of illicit S-22, urine samples were collected after 62 and 135 h and analyzed for the active drug and its major metabolic products. Liquid chromatography interfaced with high-resolution/high-accuracy (tandem) mass spectrometry was used to identify and/or confirm the predicted target analytes for sports drug testing purposes. S-22 was detected in both specimens accompanied by its glucuronic acid conjugate. This was the B-ring hydroxylated derivative of S-22 plus the corresponding glucuronide (with the phase-II metabolites being the more abundant analytes). In addition, the samples collected 62 h post-administration also contained the phase-I metabolite hydroxylated at the methyl residue (C-20

  6. Interface modification effect between p-type a-SiC:H and ZnO:Al in p-i-n amorphous silicon solar cells.

    Science.gov (United States)

    Baek, Seungsin; Lee, Jeong Chul; Lee, Youn-Jung; Iftiquar, Sk Md; Kim, Youngkuk; Park, Jinjoo; Yi, Junsin

    2012-01-18

    Aluminum-doped zinc oxide (ZnO:Al) [AZO] is a good candidate to be used as a transparent conducting oxide [TCO]. For solar cells having a hydrogenated amorphous silicon carbide [a-SiC:H] or hydrogenated amorphous silicon [a-Si:H] window layer, the use of the AZO as TCO results in a deterioration of fill factor [FF], so fluorine-doped tin oxide (Sn02:F) [FTO] is usually preferred as a TCO. In this study, interface engineering is carried out at the AZO and p-type a-SiC:H interface to obtain a better solar cell performance without loss in the FF. The abrupt potential barrier at the interface of AZO and p-type a-SiC:H is made gradual by inserting a buffer layer. A few-nanometer-thick nanocrystalline silicon buffer layer between the AZO and a-SiC:H enhances the FF from 67% to 73% and the efficiency from 7.30% to 8.18%. Further improvements in the solar cell performance are expected through optimization of cell structures and doping levels.

  7. P–n junction diodes with polarization induced p-type graded In x Ga1–x N 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 In x Ga1–x N 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 In x Ga1–x N layers needed to be capped with a thin Mg-doped In x Ga1–x N 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.

  8. CoGeNT: A Search for Low-Mass Dark Matter using p-type Point Contact Germanium Detectors

    CERN Document Server

    Aalseth, C E; Colaresi, J; Collar, J I; Leon, J Diaz; Fast, J E; Fields, N E; Hossbach, T W; Knecht, A; Kos, M S; Marino, M G; Miley, H S; Miller, M L; Orrell, J L; Yocum, K M

    2013-01-01

    CoGeNT employs p-type point-contact (PPC) germanium detectors to search for Weakly Interacting Massive Particles (WIMPs). By virtue of its low energy threshold and ability to reject surface backgrounds, this type of device allows an emphasis on low-mass dark matter candidates (WIMP mass around 10 GeV/c2). We report on the characteristics of the PPC detector presently taking data at the Soudan Underground Laboratory, elaborating on aspects of shielding, data acquisition, instrumental stability, data analysis, and background estimation. A detailed background model is used to investigate the low energy excess of events previously reported, and to assess the possibility of temporal modulations in the low-energy event rate. We conclude that the technique is ideally suited to search for the annual modulation signature expected from dark matter particle interactions in the region of WIMP mass and coupling favored by the DAMA/LIBRA claim.

  9. Experimental Studies on Doped and Co-Doped ZnO Thin Films Prepared by RF Diode Sputtering

    OpenAIRE

    2009-01-01

    Our research on the growing and characterizing of p-type ZnO thin films, prepared by radio frequency (RF) diode sputtering, mono-doped with nitrogen, and co-doped with aluminium and nitrogen, is a response of the need from p-type ZnO thin films for device applications. The dopants determine the conductivity type of the film and its physical properties. We obtained p-type ZnO thin films by RF diode sputtering and using a nitrogen dopant source. The novelty in our approach is in the use of a pl...

  10. Hybrid p-type ZnO film and n-type ZnO nanorod p-n homo-junction for efficient photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Hyun; Lee, Jun Seok; Lee, Sang Hyo; Nam, Hye Won [Novel Functional Materials and Device Lab, Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Hong, Jin Pyo, E-mail: jphong@hanyang.ac.k [Novel Functional Materials and Device Lab, Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Cha, Seoung Nam; Park, Young Jun; Kim, Jong Min [Samsung Advanced Institute of Technology, P.O. Box 11, 1 Suwon 440-600 (Korea, Republic of)

    2010-09-01

    Simple hybrid p-n homo-junctions using p-type ZnO thin films and n-type nanorods grown on fluorine tin oxide (FTO) substrates for photovoltaic applications are described. The ZnO nanorods (1.5 {mu}m) were synthesized via an aqueous solution method with zinc nitrate hexahydrate and hexamethylenetetramine on ZnO seed layers. The 10-nm-thick ZnO seed layers showed n-type conductivity on FTO substrates and were deposited with a sputtering-based method. After synthesizing ZnO nanorods, aluminum-nitride co-doped p-type ZnO films (200 nm) were efficiently grown using pre-activated nitrogen (N) plasma sources with an inductively-coupled dual-target co-sputtering system. The structural and electrical properties of hybrid p-n homo-junctions were investigated by scanning electron microscopy, transmittance spectrophotometry, and I-V measurements.

  11. Validation of a GC/MS method for the detection of two quinolinone-derived selective androgen receptor modulators in doping control analysis.

    Science.gov (United States)

    Gerace, E; Salomone, A; Fasano, F; Costa, R; Boschi, D; Di Stilo, A; Vincenti, M

    2011-04-01

    Selective androgen receptor modulators (SARMs) represent an emerging class of drugs likely to be abused in sport. For clinical applications, these substances provide a promising alternative to testosterone-replacement therapies and their advantages include oral bioavailability, androgen receptor specificity, tissue selectivity, and the absence of steroid-related side effects. Although not yet commercially available, since January 2008 SARMs have been included on the prohibited list issued yearly by the World Anti-Doping Agency (WADA), so control laboratories need to update their procedures to detect either the parent drugs or their metabolites. Within this context, two quinolinone SARM models were synthesized and automatically characterized to update the existing routine screening procedures. The conditions for the new target analytes are compatible with the existing laboratory protocols used for both in-competition and out-of-competition controls and can be included in them. Validation parameters according to ISO 17025 and WADA guidelines were successfully determined. For analytical determinations, spiked urine samples were hydrolyzed and extracted at pH 9.6 with 10 mL of tert-butyl methyl ether. Then, the analytes were subsequently converted into trimethylsilyl derivatives and detected by gas chromatography-mass spectrometry. The absence of interferents, together with excellent repeatability of both retention times and the relative abundances of diagnostic ions, allowed proper identification of all SARM analytes. The analytes' quantification was linear up to 500 ng/mL and precision criteria were satisfied (coefficient of variation less than 25% at 10 ng/mL). The limits of detection were 1 ng/mL for both SARMs, whereas recovery values were between 95.5 and 99.3%. The validated method can be efficiently used for urine screening of the 2-quinolinone-derived SARMs tested.

  12. 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...

  13. 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

    P-type ATPases catalyze the active transport of cations and phospholipids across biological membranes. Members of this large family are involved in a range of fundamental cellular processes. To date, a substantial number of P-type ATPase inhibitors have been characterized, some of which are used ...

  14. From gene engineering to gene modulation and manipulation: can we prevent or detect gene doping in sports?

    Science.gov (United States)

    Fischetto, Giuseppe; Bermon, Stéphane

    2013-10-01

    During the last 2 decades, progress in deciphering the human gene map as well as the discovery of specific defective genes encoding particular proteins in some serious human diseases have resulted in attempts to treat sick patients with gene therapy. There has been considerable focus on human recombinant proteins which were gene-engineered and produced in vitro (insulin, growth hormone, insulin-like growth factor-1, erythropoietin). Unfortunately, these substances and methods also became improper tools for unscrupulous athletes. Biomedical research has focused on the possible direct insertion of gene material into the body, in order to replace some defective genes in vivo and/or to promote long-lasting endogenous synthesis of deficient proteins. Theoretically, diabetes, anaemia, muscular dystrophies, immune deficiency, cardiovascular diseases and numerous other illnesses could benefit from such innovative biomedical research, though much work remains to be done. Considering recent findings linking specific genotypes and physical performance, it is tempting to submit the young athletic population to genetic screening or, alternatively, to artificial gene expression modulation. Much research is already being conducted in order to achieve a safe transfer of genetic material to humans. This is of critical importance since uncontrolled production of the specifically coded protein, with serious secondary adverse effects (polycythaemia, acute cardiovascular problems, cancer, etc.), could occur. Other unpredictable reactions (immunogenicity of vectors or DNA-vector complex, autoimmune anaemia, production of wild genetic material) also remain possible at the individual level. Some new substances (myostatin blockers or anti-myostatin antibodies), although not gene material, might represent a useful and well-tolerated treatment to prevent progression of muscular dystrophies. Similarly, other molecules, in the roles of gene or metabolic activators [5-aminoimidazole-4

  15. Magnetotransport measurements on modulation Si {delta}-doped pseudomorphic In{sub 0.2}Ga{sub 0.8}As/GaAs quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Babinski, A.; Li, G.; Jagadish, C. [The Australian National University, ACT (Australia). Institute of Advanced Studies, Research School of Physical Sciences and Engineering, Department of Electronic Materials Engineering

    1998-07-01

    The effect of doping concentration on electrical properties of Si {delta}-doped pseudomorphic In{sub 0} {sub .2}Ga{sub 0.} {sub 8}As/GaAs quantum wells (QWs) was examined in this work. Magnetotransport measurements were carried out in the magnetic fields up to 12 T in the dark at the temperature of T=1.7 K. The results were analysed using the fast Fourier transform (FFT). It was found that one electron subband was occupied in the QW with the doping concentrations of 2.3 x 10{sup 12} or 6.0 x 10{sup 12} cm{sup -2}. The parallel conduction was present in both samples, which increased with an increase of Si {delta}-doping concentration. The well-developed plateaus arising from the quantised Hall effect were observed in the Si {delta}-doped In{sub 0.} {sub 2}Ga{sub 0.} {sub 8}As/GaAs QW with reduced parallel conduction. The two subbands remain occupied within the V-shaped potential well formed at the Si doping plane when the Si {delta}-doping concentration was high. The results of measurements in tilted magnetic fields, confirming the attribution of FFT peaks to the particular 2DEG systems, are also presented.

  16. Growth and characterization of Arsenic doped CdTe single crystals grown by Cd-solvent traveling-heater method

    Science.gov (United States)

    Nagaoka, Akira; Han, Kyu-Bum; Misra, Sudhajit; Wilenski, Thomas; Sparks, Taylor D.; Scarpulla, Michael A.

    2017-06-01

    We report the growth of p-type As-doped, Cd-rich CdTe single crystals using metallic Cd as the solvent in the traveling-heater method. We investigate the growth process from Cd solution in terms of the solid-liquid interface shape and the effects of As incorporation on p-type doping. The resulting CdTe crystals have Cd-rich composition which enhances p-type doping. The As doping efficacy was measured for As concentrations by the combination of inductively coupled plasma mass spectrometry, capacitance-voltage measurements. The p-type doping concentration varied from 6 × 1015 to 8 × 1016 cm-3 with increasing As concentration, with an apparent doping limit just below 1017 cm-3.

  17. Synthesis and electrical characterization of intrinsic and in situ doped Si nanowires using a novel precursor

    Directory of Open Access Journals (Sweden)

    Wolfgang Molnar

    2012-07-01

    Full Text Available Perchlorinated polysilanes were synthesized by polymerization of tetrachlorosilane under cold plasma conditions with hydrogen as a reducing agent. Subsequent selective cleavage of the resulting polymer yielded oligochlorosilanes SinCl2n+2 (n = 2, 3 from which the octachlorotrisilane (n = 3, Cl8Si3, OCTS was used as a novel precursor for the synthesis of single-crystalline Si nanowires (NW by the well-established vapor–liquid–solid (VLS mechanism. By adding doping agents, specifically BBr3 and PCl3, we achieved highly p- and n-type doped Si-NWs by means of atmospheric-pressure chemical vapor deposition (APCVD. These as grown NWs were investigated by means of scanning electron microscopy (SEM and transmission electron microscopy (TEM, as well as electrical measurements of the NWs integrated in four-terminal and back-gated MOSFET modules. The intrinsic NWs appeared to be highly crystalline, with a preferred growth direction of [111] and a specific resistivity of ρ = 6 kΩ·cm. The doped NWs appeared to be [112] oriented with a specific resistivity of ρ = 198 mΩ·cm for p-type Si-NWs and ρ = 2.7 mΩ·cm for n-doped Si-NWs, revealing excellent dopant activation.

  18. Synthesis and electrical characterization of intrinsic and in situ doped Si nanowires using a novel precursor.

    Science.gov (United States)

    Molnar, Wolfgang; Lugstein, Alois; Wojcik, Tomasz; Pongratz, Peter; Auner, Norbert; Bauch, Christian; Bertagnolli, Emmerich

    2012-01-01

    Perchlorinated polysilanes were synthesized by polymerization of tetrachlorosilane under cold plasma conditions with hydrogen as a reducing agent. Subsequent selective cleavage of the resulting polymer yielded oligochlorosilanes Si(n)Cl(2) (n) (+2) (n = 2, 3) from which the octachlorotrisilane (n = 3, Cl(8)Si(3), OCTS) was used as a novel precursor for the synthesis of single-crystalline Si nanowires (NW) by the well-established vapor-liquid-solid (VLS) mechanism. By adding doping agents, specifically BBr(3) and PCl(3), we achieved highly p- and n-type doped Si-NWs by means of atmospheric-pressure chemical vapor deposition (APCVD). These as grown NWs were investigated by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM), as well as electrical measurements of the NWs integrated in four-terminal and back-gated MOSFET modules. The intrinsic NWs appeared to be highly crystalline, with a preferred growth direction of [111] and a specific resistivity of ρ = 6 kΩ·cm. The doped NWs appeared to be [112] oriented with a specific resistivity of ρ = 198 mΩ·cm for p-type Si-NWs and ρ = 2.7 mΩ·cm for n-doped Si-NWs, revealing excellent dopant activation.

  19. Defect Chemistry Study of Nitrogen Doped ZnO Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Miami University: Dr. Lei L. Kerr (PI, PD) Wright State University: Dr. David C. Look (PI) and Dr. Zhaoqiang Fang (Co-PI)

    2009-11-29

    Our team has investigated the defect chemistry of ZnO:N and developed a thermal evaporation (vapor-phase) method to synthesis p-type ZnO:N. Enhanced p-type conductivity of nitrogen doped ZnO via nano/micro structured rods and Zn-rich Co-doping process were studied. Also, an extended X-Ray absorption fine structure study of p-type nitrogen doped ZnO was conducted. Also reported are Hall-effect, photoluminescence, and DLTS studies.

  20. Effect of Ga doping and point defect on magnetism of ZnO

    Science.gov (United States)

    Hou, Qingyu; Zhao, Chunwang; Jia, Xiaofang; Qu, Lingfeng

    2017-02-01

    The combined influence mechanism of Ga doping and Zn vacancy or O vacancy on magnetism of ZnO is studied using the first-principle calculation. The coexistence of Ga doping and Zn vacancy can achieve a Curie temperature higher than room temperature and the Ga doped ZnO system is a p-type diluted degenerate semiconductor with metalized ferromagnetism. The magnetism of the doping system of Ga doping and Zn vacancy is mainly contributed by double-exchange interaction through the holes of Zn vacancy taking carrier as medium. However, the system of Ga doping and O vacancy is non-magnetic. In the coexistence of Ga doping and Zn vacancy or O vacancy, a close relative distance between doping and vacancy will reduce the formation energy of the doping system but increase the easiness of doping and vacancy, as well as enhance the stability of the doping system.

  1. Effect of Ga doping and point defect on magnetism of ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Qingyu [College of Science, Inner Mongolia University of Technology, 010051 Hohhot (China); Zhao, Chunwang, E-mail: cwzhao@shmtu.edu.cn [College of Arts and Sciences, Shanghai Maritime University, 201306 Shanghai (China); Jia, Xiaofang; Qu, Lingfeng [College of Science, Inner Mongolia University of Technology, 010051 Hohhot (China)

    2017-02-01

    The combined influence mechanism of Ga doping and Zn vacancy or O vacancy on magnetism of ZnO is studied using the first-principle calculation. The coexistence of Ga doping and Zn vacancy can achieve a Curie temperature higher than room temperature and the Ga doped ZnO system is a p-type diluted degenerate semiconductor with metalized ferromagnetism. The magnetism of the doping system of Ga doping and Zn vacancy is mainly contributed by double-exchange interaction through the holes of Zn vacancy taking carrier as medium. However, the system of Ga doping and O vacancy is non-magnetic. In the coexistence of Ga doping and Zn vacancy or O vacancy, a close relative distance between doping and vacancy will reduce the formation energy of the doping system but increase the easiness of doping and vacancy, as well as enhance the stability of the doping system.

  2. Thermal effect mechanism of magnetoresistance in p-type diamond films

    Institute of Scientific and Technical Information of China (English)

    Qin Guo-Ping; Kong Chun-Yang; Ruan Hai-Bo; Huang Gui-Juan; Cui Yu-Ting; Fang Liang

    2010-01-01

    Based on the analysis and the discussion of the influence of thermal ionization energy and various scatterings on magnetoresistance(MR) of p-type diamond films, a revised model of valence band split-off over temperature is put forward, and a corresponding calculation formula is given for the MR of p-type diamond films (Corbino discs). It is shown that the theoretical calculation that the MR of diamond films changes with temperature is consistent with the experiment. The influence of Fermi energy level on MR of diamond films is discussed. Additionally, the thermal effect mechanism of MR in p-type diamond films is also explored.

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

    OpenAIRE

    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 ...

  4. Nanocrystalline Fe-Fe2O3 particle-deposited N-doped graphene as an activity-modulated Pt-free electrocatalyst for oxygen reduction reaction

    Science.gov (United States)

    Dhavale, Vishal M.; Singh, Santosh K.; Nadeema, Ayasha; Gaikwad, Sachin S.; Kurungot, Sreekumar

    2015-11-01

    The size-controlled growth of nanocrystalline Fe-Fe2O3 particles (2-3 nm) and their concomitant dispersion on N-doped graphene (Fe-Fe2O3/NGr) could be attained when the mutually assisted redox reaction between NGr and Fe3+ ions could be controlled within the aqueous droplets of a water-in-oil emulsion. The synergistic interaction existing between Fe-Fe2O3 and NGr helped the system to narrow down the overpotential for the oxygen reduction reaction (ORR) by bringing a significant positive shift to the reduction onset potential, which is just 15 mV higher than its Pt-counterpart. In addition, the half-wave potential (E1/2) of Fe-Fe2O3/NGr is found to be improved by a considerable amount of 135 mV in comparison to the system formed by dispersing Fe-Fe2O3 nanoparticles on reduced graphene oxide (Fe-Fe2O3/RGO), which indicates the presence of a higher number of active sites in Fe-Fe2O3/NGr. Despite this, the ORR kinetics of Fe-Fe2O3/NGr are found to be shifted significantly to the preferred 4-electron-transfer pathway compared to NGr and Fe-Fe2O3/RGO. Consequently, the H2O2% was found to be reduced by 78.3% for Fe-Fe2O3/NGr (13.0%) in comparison to Fe-Fe2O3/RGO (51.2%) and NGr (41.0%) at -0.30 V (vs. Hg/HgO). This difference in the yield of H2O2 formed between the systems along with the improvements observed in terms of the oxygen reduction onset and E1/2 in the case of Fe-Fe2O3/NGr reveals the activity modulation achieved for the latter is due to the coexistence of factors such as the presence of the mixed valancies of iron nanoparticles, small size and homogeneous distribution of Fe-Fe2O3 nanoparticles and the electronic modifications induced by the doped nitrogen in NGr. A controlled interplay of these factors looks like worked favorably in the case of Fe-Fe2O3/NGr. As a realistic system level validation, Fe-Fe2O3/NGr was employed as the cathode electrode of a single cell in a solid alkaline electrolyte membrane fuel cell (AEMFC). The system could display an open

  5. Effective surface passivation of p-type crystalline silicon with silicon oxides formed by light-induced anodisation

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Jie, E-mail: j.cui@unsw.edu.au [School of Photovoltaic and Renewable Energy Engineering, The University of New South Wales, Sydney 2052 (Australia); Grant, Nicholas [Centre for Sustainable Energy Systems, Australian National University, Canberra, A.C.T. 0200 (Australia); Lennon, Alison [School of Photovoltaic and Renewable Energy Engineering, The University of New South Wales, Sydney 2052 (Australia)

    2014-12-30

    Highlights: • The surface passivation by anodic SiO{sub 2} formed by light-induced anodisation is investigated. • The anodic SiO{sub 2} grows lower temperatures with shorter growth times. After annealing in oxygen and then forming gas the effective minority carrier lifetime is increased to 150 μs. • It shows a very low positive Q{sub eff} of 3.4 × 10{sup 11} cm{sup −2}, a moderate D{sub it} of 6 × 10{sup 11} eV{sup −1} cm{sup −2}. • It has a very low leakage current density suggesting its application in solar cell as a functional dielectric. - Abstract: Electronic surface passivation of p-type crystalline silicon by anodic silicon dioxide (SiO{sub 2}) was investigated. The anodic SiO{sub 2} was grown by light-induced anodisation (LIA) in diluted sulphuric acid at room temperature, a process that is significantly less-expensive than thermal oxidation which is widely-used in silicon solar cell fabrication. After annealing in oxygen and then forming gas at 400 °C for 30 min, the effective minority carrier lifetime of 3–5 Ω cm, boron-doped Czochralski silicon wafers with a phosphorus-doped 80 Ω/□ emitter and a LIA anodic SiO{sub 2} formed on the p-type surface was increased by two orders of magnitude to 150 μs. Capacitance–voltage measurements demonstrated a very low positive charge density of 3.4 × 10{sup 11} cm{sup −2} and a moderate density of interface states of 6 × 10{sup 11} eV{sup −1} cm{sup −2}. This corresponded to a silicon surface recombination velocity of 62 cm s{sup −1}, which is comparable with values reported for other anodic SiO{sub 2} films, which required higher temperatures and longer growth times, and significantly lower than oxides grown by chemical vapour deposition techniques. Additionally, a very low leakage current density of 3.5 × 10{sup −10} and 1.6 × 10{sup −9} A cm{sup −2} at 1 and −1 V, respectively, was measured for LIA SiO{sub 2} suggesting its potential application as insulation layer in

  6. Origin and evolution of metal P-type ATPases in Plantae (Archaeplastida)

    OpenAIRE

    2014-01-01

    Metal ATPases are a subfamily of P-type ATPases involved in the transport of metal cations across biological membranes. They all share an architecture featuring eight transmembrane domains in pairs of two and are found in prokaryotes as well as in a variety of Eukaryotes. In Arabidopsis thaliana, eight metal P-type ATPases have been described, four being specific to copper transport and four displaying a broader metal specificity, including zinc, cadmium and possibly copper and calcium. So fa...

  7. Dual-donor (Zn(i) and V(O)) mediated ferromagnetism in copper-doped ZnO micron-scale polycrystalline films: a thermally driven defect modulation process.

    Science.gov (United States)

    Hu, Liang; Huang, Jun; He, Haiping; Zhu, Liping; Liu, Shijiang; Jin, Yizheng; Sun, Luwei; Ye, Zhizhen

    2013-05-07

    The paper reports robust ferromagnetic Cu-doped ZnO micron-scale polycrystalline films via spin-coating using high-quality doped nanocrystals. A reliable magnetic response is observed in the 900 °C vacuum annealed film without any ferromagnetic contribution from other sources. Post-annealing treatment in terms of atmosphere and temperature can control the proportion of oxygen vacancies (V(O)) and zinc interstitials (Zn(i)) defects and further help to precisely regulate defect-related ferromagnetic behavior. Complex charge transfer processes derived from dual-donor (Zn(i) and V(O)) to Cu acceptor are revealed by photoluminescence (PL) and electron paramagnetic resonance (EPR) spectra. Based on the above, specific charge transfer (CT)-type Stoner splitting and indirect double-exchange mechanisms are proposed to understand the ferromagnetic origin. The improvable FM performance and annealing-specific modulation further indicate that a thermal driven process can delicately tailor the magnetic property of the transition metal ion-doped ZnO system.

  8. Theoretical luminescence spectra in p-type quantum wells and superlattices based on InGaAsN

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Thiago Freire de; Rodrigues, Sara Cristina Pinto [Universidade Federal Rural de Pernambuco (UFRPE), Recife, PE (Brazil). Dept. de Fisica; Silva Junior, Eronides Felisberto da [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Fisica; Sipahi, Guilherme Matos [Universidade de Sao Paulo (IFSC/USP), Sao Carlos, SP (Brazil). Inst. de Fisica; Scolfaro, Luisa Maria Ribeiro [Texas State University, San Marcos, TX (United States), Dept. of Physics

    2012-07-01

    Full text: In the past few years, the dilute nitride system, InGaAsN, is proposed as a good candidate for several device applications. InGaAsN is considered a promising material for laser devices working at 1:3 or 1:5{mu}m and high-efficiency multijunction solar cells. Incorporation of In and N into GaAs result in a strong redshift of the emission wavelength. Besides, the strain can be minimized since the opposite effect of In and N on the lattice constant enables lattice matching of InGaAsN on GaAs. However, despite their great potential for applications, the understanding of their physical properties is rather incomplete. In particular, the dominant mechanisms of light emission in these alloys and their dependence on the nitrogen composition are not well established. Such information is crucial not only for a better understanding of the optical properties of the nitrogen containing III-V alloys, but also for a better technological control of alloy formation and optimization light emission efficiency. Another point concerns to investigation in p-type doping in InGaAsN. This is of great importance since, for example, can improve the transport in HBT (Heterojunction Bipolar Transistors) devices. In this work we report on theoretical luminescence spectra calculations for p-doped GaAs/InGaAsN quantum wells and superlattices. The calculations are performed within the k-vector.p-vector method by solving the full 8 x 8 Kane Hamiltonian, generalized to treat different materials. Strain effects due the lattice mismatch between InGaAsN and GaAs are taken into account. By varying the acceptor concentration we analyze the effect of exchange-correlation, which plays an important role in profile potential and electronic transition. These results can explain several important aspects about optical properties in these systems. (author)

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

    Science.gov (United States)

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

    2015-12-01

    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 ZeT 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.

  10. RETRACTED: P-type Zno thin films fabricated by Al-N co-doping method at different substrate temperature

    Science.gov (United States)

    Yuan, Guodong; Ye, Zhizhen; Qian, Qing; Zhu, Liping; Huang, Jingyun; Zhao, Binghui

    2005-01-01

    This article has been retracted at the request of the Editor-in-Chief. Please see Elsevier Policy on Article Withdrawal ( http://www.elsevier.com/locate/withdrawalpolicy). The editors and publisher would like to confirm the retraction of this paper at the request of the author Guodong Yuan. Reason: The SIMS profile published in this paper had already been included in articles published in Mater. Lett., 58 (2004) 3741-3744, and Thin Solid Films, 484 (2005) 420-425 describing a sample prepared under different conditions. The author did not notify either the Journal of Crystal Growth Editors or the coauthors of this fact. The author apologizes sincerely to the readers, referees, and Editors for violating the guidelines of ethical publication.Also the author apologizes to the coauthors for mishandling of the manuscript.

  11. Effective field theory and Ab-initio calculation of p-type (Ga, Fe)N within LDA and SIC approximation

    Energy Technology Data Exchange (ETDEWEB)

    Salmani, E. [LMPHE, associe au CNRST (URAC 12), Faculte des Sciences, Universite Mohammed V-Agdal, Rabat (Morocco); Mounkachi, O. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); Ez-Zahraouy, H., E-mail: ezahamid@fsr.ac.ma [LMPHE, associe au CNRST (URAC 12), Faculte des Sciences, Universite Mohammed V-Agdal, Rabat (Morocco); El Kenz, A. [LMPHE, associe au CNRST (URAC 12), Faculte des Sciences, Universite Mohammed V-Agdal, Rabat (Morocco); Hamedoun, M. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); Benyoussef, A. [LMPHE, associe au CNRST (URAC 12), Faculte des Sciences, Universite Mohammed V-Agdal, Rabat (Morocco); Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco)

    2013-03-15

    Based on first-principles spin-density functional calculations, using the Korringa-Kohn-Rostoker method combined with the coherent potential approximation, we investigated the half-metallic ferromagnetic behavior of (Ga, Fe)N co-doped with carbon within the self-interaction-corrected local density approximation. Mechanism of hybridization and interaction between magnetic ions in p-type (Ga, Fe)N is investigated. Stability energy of ferromagnetic and disorder local moment states was calculated for different carbon concentration. The local density and the self-interaction-corrected approximations have been used to explain the strong ferromagnetic interaction observed and the mechanism that stabilizes this state. The transition temperature to the ferromagnetic state has been calculated within the effective field theory, with a Honmura-Kaneyoshi differential operator technique. - Highlights: Black-Right-Pointing-Pointer The paper focus on the study the magnetic properties and electronic structure of p-type (Ga, Fe)N within LDA and SIC approximation. Black-Right-Pointing-Pointer These methods allow us to explain the strong ferromagnetic interaction observed and the mechanism for its stability and the mechanism of hybridization and interaction between magnetic ions in p-type (Ga, Fe). Black-Right-Pointing-Pointer The results obtained are interesting and can be serve as a reference in the field of dilute magnetic semi conductor.

  12. Combinatorial discovery through a distributed outreach program: investigation of the photoelectrolysis activity of p-type Fe, Cr, Al oxides.

    Science.gov (United States)

    Rowley, John G; Do, Thanh D; Cleary, David A; Parkinson, B A

    2014-06-25

    We report the identification of a semiconducting p-type oxide containing iron, aluminum, and chromium (Fe2-x-yCrxAlyO3) with previously unreported photoelectrolysis activity that was discovered by an undergraduate scientist participating in the Solar Hydrogen Activity research Kit (SHArK) program. The SHArK program is a distributed combinatorial science outreach program designed to provide a simple and inexpensive way for high school and undergraduate students to participate in the search for metal oxide materials that are active for the photoelectrolysis of water. The identified Fe2-x-yCrxAlyO3 photoelectrolysis material possesses many properties that make it a promising candidate for further optimization for potential application in a photoelectrolysis device. In addition to being composed of earth abundant elements, the FeCrAl oxide material has a band gap of 1.8 eV. Current-potential measurements for Fe2-x-yCrxAlyO3 showed an open circuit photovoltage of nearly 1 V; however, the absorbed photon conversion efficiency for hydrogen evolution was low (2.4 × 10(-4) at 530 nm) albeit without any deposited hydrogen evolution catalyst. X-ray diffraction of the pyrolyzed polycrystalline thin Fe2-x-yCrxAlyO3 film on fluorine-doped tin oxide substrates shows a hexagonal phase (hematite structure) and scanning electron microscope images show morphology consisting of small crystallites.

  13. High performance p-type segmented leg of misfit-layered cobaltite and half-Heusler alloy

    DEFF Research Database (Denmark)

    Le, Thanh Hung; Van Nong, Ngo; Snyder, Gerald Jeffrey;

    2015-01-01

    In this study, a segmented p-type leg of doped misfit-layered cobaltite Ca2.8Lu0.15Ag0.05Co4O9+δ and half-Heusler Ti0.3Zr0.35Hf0.35CoSb0.8Sn0.2 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, DT, 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. 2015...

  14. Low specific contact resistance on epitaxial p-type 4H-SiC with a step-bunching surface

    Institute of Scientific and Technical Information of China (English)

    韩超; 张玉明; 宋庆文; 汤晓燕; 张义门; 郭辉; 王悦湖

    2015-01-01

    This paper reports the performances of Ti/Al based ohmic contacts fabricated on highly doped p-type 4H-SiC epitaxial layer which has a severe step-bunching surface. Different contact schemes are investigated based on the Al:Ti composition with no more than 50 at.%Al. The specific contact resistance (SCR) is obtained to be as low as 2.6 × 10−6Ω·cm2 for the bilayered Ti(100 nm)/Al(100 nm) contact treated with 3 min rapid thermal annealing (RTA) at 1000◦C. The microstructure analyses examined by physical and chemical characterization techniques reveal an alloy-assisted ohmic contact formation mechanism, i.e., a high degree of alloying plays a decisive role in forming the interfacial ternary Ti3SiC2 dominating the ohmic behavior of the Ti/Al based contact. Furthermore, a globally covered Ti3SiC2 layer with (0001)-oriented texture can be formed, regardless of the surface step bunching as well as its structural evolution during the metallization annealing.

  15. Limits on the use of cobalt sulfide as anode of p-type dye-sensitized solar cells

    Science.gov (United States)

    Bonomo, Matteo; Congiu, Mirko; De Marco, Maria Letizia; Dowling, Denis P.; Di Carlo, Aldo; Graeff, Carlos F. O.; Dini, Danilo

    2017-06-01

    Thin films of cobalt sulfide (CoS) of thickness l  traditional platinized fluorine-doped indium oxide (Pt-FTO) due to the lower cost of the starting materials (Co salts) and the easier procedure of deposition onto large area substrates. The latter process was carried out via direct precipitation of CoS from aqueous solutions. The photoconversion efficiency (η) of the corresponding device was 0.07%. This value is about 35% less than the efficiency that is obtained with the analogous p-DSC employing the Pt-FTO anode (η  =  0.11). Unlike p-DSCs based on Pt-FTO anodes, the photoelectrochemical cells employing CoS electrodes showed that this anodic material was not able to sustain the photocurrent densities generated by P1-sensitized NiO at a given photopotential. Illumination of the p-DSCs with CoS anodes and P1-sensitized NiO cathodes actually induced the reverse bias of the photoelectrochemical cell with CoS behaving like a p-type semiconductor with no degeneracy. Dedicated to Professor Roberto Federici on the occasion of his retirement.

  16. P-type AlAs/[GaAs/AlAs] Semiconductor/Superlattice DBR Grown by MBE

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A p-type AlAs(70.2 nm)/16.5 period [GaAs(3 nm)/AlAs(0.7 nm)] semiconductor/superlatice distributed Bragg reflector (DBR) has been grown on n+-GaAs(100) substrate by V80H molecular beam epitaxy system. Experimental reflection spectrum shows that its central wavelength is 820 nm, with the peak reflectivity for 10-pair DBR of as high as 96 %, and the reflection bandwidth of as wide as 90 nm. We formed a 20×20 μm2 square mesa to measure the series resistance using wet chemical etching. From the measurement result, the series resistance of about 50 Ω is obtained at a moderate doping (3×1018 cm-3). Finally, the dependence of the resistance of the DBR on the temperature is analyzed. From the experimental result, it is found that the mechanism of the low series resistance of this kind of DBR may increase the tunneling current in the semiconductor/superlattice mirror structure, which will result in a decrease in series resistance.

  17. Ultrafast Dynamics of Hole Injection and Recombination in Organometal Halide Perovskite Using Nickel Oxide as p-Type Contact Electrode.

    Science.gov (United States)

    Corani, Alice; Li, Ming-Hsien; Shen, Po-Shen; Chen, Peter; Guo, Tzung-Fang; El Nahhas, Amal; Zheng, Kaibo; Yartsev, Arkady; Sundström, Villy; Ponseca, Carlito S

    2016-04-01

    There is a mounting effort to use nickel oxide (NiO) as p-type selective electrode for organometal halide perovskite-based solar cells. Recently, an overall power conversion efficiency using this hole acceptor has reached 18%. However, ultrafast spectroscopic investigations on the mechanism of charge injection as well as recombination dynamics have yet to be studied and understood. Using time-resolved terahertz spectroscopy, we show that hole transfer is complete on the subpicosecond time scale, driven by the favorable band alignment between the valence bands of perovskite and NiO nanoparticles (NiO(np)). Recombination time between holes injected into NiO(np) and mobile electrons in the perovskite material is shown to be hundreds of picoseconds to a few nanoseconds. Because of the low conductivity of NiO(np), holes are pinned at the interface, and it is electrons that determine the recombination rate. This recombination competes with charge collection and therefore must be minimized. Doping NiO to promote higher mobility of holes is desirable in order to prevent back recombination.

  18. Formation of Si or Ge nanodots in Si3N4 with in-situ donor modulation doping of adjacent barrier material

    Directory of Open Access Journals (Sweden)

    D. König

    2013-01-01

    Full Text Available Conventional doping of small nanodots does not provide majority carriers due to self-purification effects and much increased ionisation energies of dopants presenting point defects. Adjacent barrier layers to Si-rich Si3N4 can be doped by excess Si in-situ with the segregation anneal for Si nanodot formation. Donor doping of AlxGa1−xN (0 ⩽ x ⩽ 1 with Si is an established process. Material properties and process compatibility of AlxGa1−xN render it suitable as barrier for Si nanodot superlattices. Ab-initio calculations showed that Ge also works as a donor in AlN, extending the material range to Ge and SiGe nanodots in Si3N4.

  19. 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.

  20. 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.

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

    Science.gov (United States)

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

    2016-05-01

    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.

  2. Controllable optical modulation of blue/green up-conversion fluorescence from Tm3+ (Er3+) single-doped glass ceramics upon two-step excitation of two-wavelengths

    Science.gov (United States)

    Chen, Zhi; Kang, Shiliang; Zhang, Hang; Wang, Ting; Lv, Shichao; Chen, Qiuqun; Dong, Guoping; Qiu, Jianrong

    2017-04-01

    Optical modulation is a crucial operation in photonics for network data processing with the aim to overcome information bottleneck in terms of speed, energy consumption, dispersion and cross-talking from conventional electronic interconnection approach. However, due to the weak interactions between photons, a facile physical approach is required to efficiently manipulate photon-photon interactions. Herein, we demonstrate that transparent glass ceramics containing LaF3: Tm3+ (Er3+) nanocrystals can enable fast-slow optical modulation of blue/green up-conversion fluorescence upon two-step excitation of two-wavelengths at telecom windows (0.8-1.8 μm). We show an optical modulation of more than 1500% (800%) of the green (blue) up-conversion fluorescence intensity, and fast response of 280 μs (367 μs) as well as slow response of 5.82 ms (618 μs) in the green (blue) up-conversion fluorescence signal, respectively. The success of manipulating laser at telecom windows for fast-slow optical modulation from rear-earth single-doped glass ceramics may find application in all-optical fiber telecommunication areas.

  3. Gene doping in modern sport.

    Directory of Open Access Journals (Sweden)

    MAREK SAWCZUK

    2009-01-01

    Full Text Available Background: The subject of this paper is gene doping, which should be understood as "he non-therapeutic use of cells, genes, genetic elements, or of the modulation of gene expression, having the capacity to improve athletic performance". The authors of this work, based on the review of literature and previous research, make an attempt at wider characterization of gene doping and the discussion of related potential threats.Methods: This is a comprehensive survey of literature on the latest applications of molecular biology in medicine. The analysis involves a dozen scientific databases examined in order to find genes used in gene therapy and potentially useful in gene doping. Results: The obtained results enable better recognition of gene doping and indicate genes used in medicine that could be used in gene doping. This paper describes potential effects of their use and associated risk, and predicts the possible developments of gene doping in the future. Conclusion: Gene doping is undoubtedly a part of modern sport. Although WADA included gene doping on the list of banned methods as early as 2004, as previously stated above, it has not managed to develop efficient methods of detection.

  4. 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.

  5. DyP-type peroxidases comprise a novel heme peroxidase family.

    Science.gov (United States)

    Sugano, Y

    2009-04-01

    Dye-decolorizing peroxidase (DyP) is produced by a basidiomycete (Thanatephorus cucumeris Dec 1) and is a member of a novel heme peroxidase family (DyP-type peroxidase family) that appears to be distinct from general peroxidases. Thus far, 80 putative members of this family have been registered in the PeroxiBase database (http://peroxibase.isbsib.ch/) and more than 400 homologous proteins have been detected via PSI-BLAST search. Although few studies have characterized the function and structure of these proteins, they appear to be bifunctional enzymes with hydrolase or oxygenase, as well as typical peroxidase activities. DyP-type peroxidase family suggests an ancient root compared with other general peroxidases because of their widespread distribution in the living world. In this review, firstly, an outline of the characteristics of DyP from T. cucumeris is presented and then interesting characteristics of the DyP-type peroxidase family are discussed.

  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......P-type ATPases catalyze the active transport of cations and phospholipids across biological membranes. Members of this large family are involved in a range of fundamental cellular processes. To date, a substantial number of P-type ATPase inhibitors have been characterized, some of which are used...... as drugs. In this work a library of natural compounds was screened and we first identified curcuminoids as plasma membrane H+-ATPases inhibitors in plant and fungal cells. We also found that some of the commercial curcumins contain several curcuminoids. Three of these were purified and, among...

  7. Lateral photovoltaic effect observed in doping-modulated GaAs/Alsub>0.3sub>Gasub>0.7sub>As.

    Science.gov (United States)

    Liu, Ji Hong; Qiao, Shuang; Liang, BaoLai; Wang, ShuFang; Fu, GuangSheng

    2017-02-20

    For photovoltaic effect (PE), both barrier height and carrier lifetime are all very important factors. However, how to distinguish their contributions to the PE is very difficult. In this paper, we prepared a series of GaAs/Alsub>0.3sub>Gasub>0.7sub>As two dimensional electron gas (2DEG) with typical Alsub>0.3sub>Gasub>0.7sub>As doping concentration of 0.6 × 1018/cm3, 1.2 × 1018/cm3, and 2.5 × 1018/cm3, respectively (sample number: #1, #2, #3), and studied their lateral photovoltaic effects (LPEs). It is found that their position sensitivities all increase with both laser wavelength and laser power. However, the position sensitivity exhibits a non-monotonic behavior with increasing doping concentration, which can be mainly ascribed to the doping concentration-dependent carrier lifetime, especially in the low power regime. With increasing laser power gradually, the position sensitivity difference between sample #1 and sample #2 is still large and increases a little, while the position sensitivity of sample #3 approaches to that of sample #2, suggesting that the doping concentration-dependent barrier height also starts to play an important role in the high power regime. Our results will provide important information for the design and development of novel and multifunctional PE devices.

  8. Design of n - and p -type oxide thermoelectrics in LaNiO3/SrTiO3(001 ) superlattices exploiting interface polarity

    Science.gov (United States)

    Geisler, Benjamin; Blanca-Romero, Ariadna; Pentcheva, Rossitza

    2017-03-01

    We investigate the structural, electronic, transport, and thermoelectric properties of LaNiO3/SrTiO3(001 ) superlattices containing either exclusively n - or p -type interfaces or coupled interfaces of opposite polarity by using density functional theory calculations with an on-site Coulomb repulsion term. The results show that significant octahedral tilts are induced in the SrTiO3 part of the superlattice. Moreover, the La-Sr distances and Ni-O out-of-plane bond lengths at the interfaces exhibit a distinct variation by about 7 % with the sign of the electrostatic doping. In contrast to the much studied LaAlO3/SrTiO3 system, the charge mismatch at the interfaces is exclusively accommodated within the LaNiO3 layers, whereas the interface polarity leads to a band offset and to the formation of an electric field within the coupled superlattice. Features of the electronic structure indicate an orbital-selective quantization of quantum well states. The potential- and confinement-induced multiband splitting results in complex cylindrical Fermi surfaces with a tendency towards nesting that depends on the interface polarity. The analysis of the thermoelectric response reveals a particularly large positive Seebeck coefficient (135 μ V /K) and a high figure of merit (0.35) for room-temperature cross-plane transport in the p -type superlattice that is attributed to the participation of the SrTiO3 valence band. Superlattices with either n - or p -type interfaces show cross-plane Seebeck coefficients of opposite sign and thus emerge as a platform to construct an oxide-based thermoelectric generator with structurally and electronically compatible n - and p -type oxide thermoelectrics.

  9. Controlling hyperchaos in erbium-doped fibre laser

    Institute of Scientific and Technical Information of China (English)

    张胜海; 沈柯

    2003-01-01

    The dual-ring erbium-doped fibre laser shows a hyperchaotic behaviour under some conditions. The hyperchaotic behaviour can be well controlled to enter into periodicity by modulating the pumping in one of the two rings. The period is different for different modulation index at the same modulation frequency, or for different modulation frequency at the same modulation index.

  10. Cat-doping: Novel method for phosphorus and boron shallow doping in crystalline silicon at 80 °C

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, Hideki; Hayakawa, Taro; Ohta, Tatsunori; Nakashima, Yuki; Miyamoto, Motoharu; Thi, Trinh Cham; Koyama, Koichi; Ohdaira, Keisuke [Japan Advanced Institute of Science and Technology (JAIST), Asahidai, Nomi-shi, Ishikawa-ken 923-1292 (Japan)

    2014-09-21

    Phosphorus (P) or boron (B) atoms can be doped at temperatures as low as 80 to 350 °C, when crystalline silicon (c-Si) is exposed only for a few minutes to species generated by catalytic cracking reaction of phosphine (PH₃) or diborane (B₂H₆) with heated tungsten (W) catalyzer. This paper is to investigate systematically this novel doping method, “Cat-doping”, in detail. The electrical properties of P or B doped layers are studied by the Van der Pauw method based on the Hall effects measurement. The profiles of P or B atoms in c-Si are observed by secondary ion mass spectrometry mainly from back side of samples to eliminate knock-on effects. It is confirmed that the surface of p-type c-Si is converted to n-type by P Cat-doping at 80 °C, and similarly, that of n-type c-Si is to p-type by B Cat-doping. The doping depth is as shallow as 5 nm or less and the electrically activated doping concentration is 10¹⁸ to 10¹⁹cm⁻³ for both P and B doping. It is also found that the surface potential of c-Si is controlled by the shallow Cat-doping and that the surface recombination velocity of minority carriers in c-Si can be enormously lowered by this potential control.

  11. Synchronous Chaos Generation in an ^-Doped Fiber Laser System

    National Research Council Canada - National Science Library

    Gomez-Pavon, L. C; Munoz-Pacheco, J. M; Luis-Ramos, A

    2015-01-01

    ...+ -doped fiber lasers is experimentally analyzed. Using a single amplitude modulator in the system, synchronous chaos generation is obtained at two different modulation frequencies, i.e., 10.38 and 3.85 MHz...

  12. Relative Frequencies of G and P Types among Rotaviruses from Indian Diarrheic Cow and Buffalo Calves

    Science.gov (United States)

    Gulati, Baldev R.; Nakagomi, Osamu; Koshimura, Yumi; Nakagomi, Toyoko; Pandey, Ramayan

    1999-01-01

    While an increasing number of studies suggest that there is a high prevalence of rotaviruses with P8[11], a typical P type of bovine rotavirus (BRV), among human neonates or infants in India, no data are available on the distribution of G and P types of Indian BRVs. Thus, fecal specimens were collected from cow and buffalo calves under 1 month of age on organized dairy farms in India during the period between 1994 and 1997, and 36 rotavirus-positive specimens were used to determine the relative frequencies of the G and P types of Indian BRVs. As to the G type, G10 was predominant (83%), followed by G6 (6%). The majority (94%) of BRVs had P8[11], and only one isolate possessed P6[1]. The most common combination of G and P types was G10P8[11] (81%), followed by G6P6[1] (3%) and G6P8[11] (3%). The high prevalence of BRVs possessing P8[11] VP4s strongly supports the hypothesis that BRVs may cross the host species barrier and circulate among neonates in India. PMID:10325385

  13. 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.

  14. Origin and evolution of metal p-Type ATPases in Plantae (Archaeplastida

    Directory of Open Access Journals (Sweden)

    Marc eHanikenne

    2014-01-01

    Full Text Available Metal ATPases are a subfamily of P-type ATPases involved in the transport of metal cations across biological membranes. They all share an architecture featuring eight transmembrane domains in pairs of two and are found in prokaryotes as well as in a variety of Eukaryotes. In Arabidopsis thaliana, eight metal P-type ATPases have been described, four being specific to copper transport and four displaying a broader metal specificity, including zinc, cadmium and possibly copper and calcium. So far, few efforts have been devoted to elucidating the origin and evolution of these proteins in Eukaryotes. In this work, we use large-scale phylogenetics to show that metal P-type ATPases form a homogenous group among P-type ATPases and that their specialisation into either monovalent (Cu or divalent (Zn, Cd… metal transport stems from a gene duplication that took place early in the evolution of Life. Then, we demonstrate that the four subgroups of plant metal ATPases all have a different evolutionary origin and a specific taxonomic distribution, only one tracing back to the cyanobacterial progenitor of the chloroplast. Finally, we examine the subsequent evolution of these proteins in green plants and conclude that the genes thoroughly characterised in model organisms are often the result of lineage-specific gene duplications, which calls for caution when attempting to infer function from sequence similarity alone in non-model organisms.

  15. Synthesis of p-type and n-type nickel ferrites and associated electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Šutka, Andris, E-mail: andris.sutka@rtu.lv [Faculty of Material Science and Applied Chemistry, Riga Technical University, Paula Valdena 3, Riga, LV-1048 (Latvia); Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Pärna, Rainer [Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Estonian Nanotechnology Competence Centre, Ravila 14c, 50411, 51014 Tartu (Estonia); Käämbre, Tanel [Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Kisand, Vambola [Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Estonian Nanotechnology Competence Centre, Ravila 14c, 50411, 51014 Tartu (Estonia)

    2015-01-01

    We used sol–gel auto combustion to synthesize nickel ferrites of p-type and n-type conductivity by controlling the relative amounts of nickel and iron during synthesis. The obtained samples have been characterized by XRD, FE-SEM, electrical measurements and XPS. We observe huge differences in the effect of grain size on the electrical resistivity between the p-type and the n-type material when the grain size increases from nano to micro scale during annealing at temperatures from 900 {sup o}C to 1300 {sup o}C. The observed resistivity decrease (due to grain size) is four orders of magnitude in the n-type nickel ferrite, whereas the p-type material remains virtually unaffected. We rationalize this drastic difference to stem from a reverse contrast of the surface (grain shell) versus bulk (grain core) conductivity between p- and n-type ferrite. With the grain shells in p-type the easier charge carrier path the effect of scatter at grain boundaries is accordingly diminished, whereas in the n-type charge transport properties are controlled by (the number of) grain boundaries in a conduction path.

  16. A structural and functional perspective of DyP-type peroxidase family.

    Science.gov (United States)

    Yoshida, Toru; Sugano, Yasushi

    2015-05-15

    Dye-decolorizing peroxidase from the basidiomycete Bjerkandera adusta Dec 1 (DyP) is a heme peroxidase. This name reflects its ability to degrade several anthraquinone dyes. The substrate specificity, the amino acid sequence, and the tertiary structure of DyP are different from those of the other heme peroxidase (super)families. Therefore, many proteins showing the similar amino acid sequences to that of DyP are called DyP-type peroxidase which is a new family of heme peroxidase identified in 2007. In fact, all structures of this family show a similar structure fold. However, this family includes many proteins whose amino acid sequence identity to DyP is lower than 15% and/or whose catalytic efficiency (kcat/Km) is a few orders of magnitude less than that of DyP. A protein showing an activity different from peroxidase activity (dechelatase activity) has been also reported. In addition, the precise physiological roles of DyP-type peroxidases are unknown. These facts raise a question of whether calling this family DyP-type peroxidase is suitable. Here, we review the differences and similarities of structure and function among this family and propose the reasonable new classification of DyP-type peroxidase family, that is, class P, I and V. In this contribution, we discuss the adequacy of this family name.

  17. Superconductivity in carrier-doped silicon carbide

    Directory of Open Access Journals (Sweden)

    Takahiro Muranaka, Yoshitake Kikuchi, Taku Yoshizawa, Naoki Shirakawa and Jun Akimitsu

    2008-01-01

    Full Text Available We report growth and characterization of heavily boron-doped 3C-SiC and 6H-SiC and Al-doped 3C-SiC. Both 3C-SiC:B and 6H-SiC:B reveal type-I superconductivity with a critical temperature Tc=1.5 K. On the other hand, Al-doped 3C-SiC (3C-SiC:Al shows type-II superconductivity with Tc=1.4 K. Both SiC:Al and SiC:B exhibit zero resistivity and diamagnetic susceptibility below Tc with effective hole-carrier concentration n higher than 1020 cm−3. We interpret the different superconducting behavior in carrier-doped p-type semiconductors SiC:Al, SiC:B, Si:B and C:B in terms of the different ionization energies of their acceptors.

  18. Ultrafast THz Saturable Absorption in Doped Semiconductors

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hoffmann, Matthias C.

    2011-01-01

    We demonstrate ultrafast THz saturable absorption in n-doped semiconductors by nonlinear THz time-domain spectroscopy. This effect is caused by the semiconductor conductivity modulation due to electron heating and satellite-valley scattering in strong THz fields.......We demonstrate ultrafast THz saturable absorption in n-doped semiconductors by nonlinear THz time-domain spectroscopy. This effect is caused by the semiconductor conductivity modulation due to electron heating and satellite-valley scattering in strong THz fields....

  19. Liquid chromatography-high resolution/ high accuracy (tandem) mass spectrometry-based identification of in vivo generated metabolites of the selective androgen receptor modulator ACP-105 for doping control purposes.

    Science.gov (United States)

    Thevis, Mario; Thomas, Andreas; Piper, Thomas; Krug, Oliver; Delahaut, Philippe; Schänzer, Wilhelm

    2014-01-01

    Selective androgen receptor modulators (SARMs) represent an emerging class of therapeutics which have been prohibited in sport as anabolic agents according to the regulations of the World Anti-Doping Agency (WADA) since 2008. Within the past three years, numerous adverse analytical findings with SARMs in routine doping control samples have been reported despite missing clinical approval of these substances. Hence, preventive doping research concerning the metabolism and elimination of new therapeutic entities of the class of SARMs are vital for efficient and timely sports drug testing programs as banned compounds are most efficiently screened when viable targets (for example, characteristic metabolites) are identified. In the present study, the metabolism of ACP-105, a novel SARM drug candidate, was studied in vivo in rats. Following oral administration, urine samples were collected over a period of seven days and analyzed for metabolic products by Liquid chromatography-high resolution/high accuracy (tandem) mass spectrometry. Samples were subjected to enzymatic hydrolysis prior to liquid-liquid extraction and a total of seven major phase-I metabolites were detected, three of which were attributed to monohydroxylated and four to bishydroxylated ACP-105. The hydroxylation sites were assigned by means of diagnostic product ions and respective dissociation pathways of the analytes following positive or negative ionization and collisional activation as well as selective chemical derivatization. The identified metabolites were used as target compounds to investigate their traceability in a rat elimination urine samples study and monohydroxylated and bishydroxylated species were detectable for up to four and six days post-administration, respectively.

  20. In-situ Electric Field-Induced Modulation of Photoluminescence in Pr-doped Ba0.85Ca0.15Ti0.90Zr0.10O3 Lead-Free Ceramics

    Science.gov (United States)

    Sun, Hai Ling; Wu, Xiao; Chung, Tat Hang; Kwok, K. W.

    2016-01-01

    Luminescent materials with dynamic photoluminescence activity have aroused special interest because of their potential widespread applications. One proposed approach of directly and reversibly modulating the photoluminescence emissions is by means of introducing an external electric field in an in-situ and real-time way, which has only been focused on thin films. In this work, we demonstrate that real-time electric field-induced photoluminescence modulation can be realized in a bulk Ba0.85Ca0.15Ti0.90Zr0.10O3 ferroelectric ceramic doped with 0.2 mol% Pr3+, owing to its remarkable polarization reversal and phase evolution near the morphotropic phase boundary. Along with in-situ X-ray diffraction analysis, our results reveal that an applied electric field induces not only typical polarization switching and minor crystal deformation, but also tetragonal-to-rhombohedral phase transformation of the ceramic. The electric field-induced phase transformation is irreversible and engenders dominant effect on photoluminescence emissions as a result of an increase in structural symmetry. After it is completed in a few cycles of electric field, the photoluminescence emissions become governed mainly by the polarization switching, and thus vary reversibly with the modulating electric field. Our results open a promising avenue towards the realization of bulk ceramic-based tunable photoluminescence activity with high repeatability, flexible controllability, and environmental-friendly chemical process. PMID:27339815

  1. Hole transport in pure and doped hematite

    Science.gov (United States)

    Liao, Peilin; Carter, Emily A.

    2012-07-01

    Hematite (α-Fe2O3) is a promising candidate for use in photovoltaic (PV) and photoelectrochemical devices. Its poor conductivity is one major drawback. Doping hematite either p-type or n-type greatly enhances its measured conductivity and is required for potential p-n junctions in PVs. Here, we study hole transport in pure and doped hematite using an electrostatically embedded cluster model with ab initio quantum mechanics (unrestricted Hartree-Fock theory). Consistent with previous work, the model suggests that hole hopping is via oxygen anions for pure hematite. The activation energy for hole mobility is predicted to be at least 0.1 eV higher than the activation energy for electron mobility, consistent with the trend observed in experiments. We examine four dopants—magnesium(II), nickel(II), copper(II), and manganese(II/III) in direct cation substitution sites—to gain insight into the mechanism by which conductivity is improved. The activation energies are used to assess qualitative effects of different dopants. The hole carriers are predicted to be attracted to O anions near the dopants. The magnitude of the trapping effect is similar among the four dopants in their +2 oxidation states. The multivalent character of Mn doping facilitates local hole transport around Mn centers via a low-barrier O-Mn-O pathway, which suggests that higher hole mobility can be achieved with increasing Mn doping concentration, especially when a network of these low-barrier pathways is produced. Our results suggest that the experimentally observed conductivity increase in Mg-, Ni-, and Cu-doped p-type hematite is mostly due to an increase in hole carriers rather than improved mobility, and that Mg-, Ni-, and Cu-doping perform similarly, while the conductivity of Mn-doped hematite might be significantly improved in the high doping concentration limit.

  2. Origin of Photovoltage Enhancement via Interfacial Modification with Silver Nanoparticles Embedded in an a-SiC:H p-Type Layer in a-Si:H Solar Cells.

    Science.gov (United States)

    Li, Tiantian; Zhang, Qixing; Ni, Jian; Huang, Qian; Zhang, Dekun; Li, Baozhang; Wei, Changchun; Yan, Baojie; Zhao, Ying; Zhang, Xiaodan

    2017-03-17

    We used silver nanoparticles (Ag-NPs) embedded in the p-type semiconductor layer of hydrogenated amorphous silicon (a-Si:H) solar cells in the Schottky barrier contact design to modify the interface between aluminum-doped ZnO (ZnO:Al, AZO) and p-type hydrogenated amorphous silicon carbide (p-a-SiC:H) without plasmonic absorption. The high work function of the Ag-NPs provided a good channel for the transport of photogenerated holes. A p-type nanocrystalline SiC:H layer was used to compensate for the real surface defects and voids on the surface of Ag-NPs to reduce recombination at the AZO/p-type layer interface, which then enhanced the photovoltage of single-junction a-Si:H solar cells to values as high as 1.01 V. The Ag-NPs were around 10 nm in diameter and thermally stable in the p-type a-SiC:H film at the solar-cell process temperature. We will also show that a wide range of photovoltages between 1.01 and 2.89 V could be obtained with single-, double-, and triple-junction solar cells based on the single-junction a-Si:H solar cells with tunable high photovoltage. These solar cells are suitable photocathodes for solar water-splitting applications.

  3. Improvement of doping efficiency in Mg-Al0.14Ga0.86N/GaN superlattices with AlN interlayer by suppressing donor-like defects

    Institute of Scientific and Technical Information of China (English)

    Liu Ning-Yang; Chen Wei-Hua; Hu Xiao-Dong; Liu Lei; Wang Lei; Yang Wei; Li Ding; Li Lei; Cao Wen-Yu; Lu Ci-Mang; Wan Cheng-Hao

    2012-01-01

    We investigate the mechanism for the improvement of p-type doping efficiency in Mg-Al0.14Gao.86N/GaN superlattices (SLs).It is shown that the hole concentration of SLs increases by nearly an order of magnitude,from 1.1 × 1017to 9.3×1017 cm-3,when an AlN interlayer is inserted to modulate the strains.Schr(o)dinger-Poisson self-consistent calculations suggest that such an increase could be attributed to the reduction of donor-like defects caused by the strain modulation induced by the AlN interlayer.Additionally,the donor-acceptor pair emission exhibits a remarkable decrease in intensity of the cathodoluminescence spectrum for SLs with an AlN interlayer.This supports the theoretical calculations and indicates that the strain modulation of SLs could be beneficial to the donor-like defect suppression as well as the p-type doping efficiency improvement.

  4. Minority carrier lifetimes in different doped LWIR HgCdTe grown by LPE

    Science.gov (United States)

    Qiu, GuangYin; Wei, YanFeng; Sun, QuanZhi; Yang, JianRong

    2012-10-01

    The carrier lifetimes of different types of p-type doped HgCdTe(x~0.23) long wavelength infrared (LWIR) epilayers were measured which were Hg-vacancy, Au and arsenic doped ones prepared by Te-rich Liquid-phase epitaxy (LPE). By comparing the lifetimes of Hg-vacancy and extrinsic doped HgCdTe, we focus on three primary mechanisms limiting the lifetimes in these different p-type HgCdTe samples: radiative recombination, Auger recombination and Schokley-Read- Hall (SRH) Recombination. The recombination mechanism in p-type HgCdTe is the SRH recombination at low temperatures and Auger and radiative recombination at high temperature. It is found that the lifetime of As-doped and Au-doped HgCdTe is far longer than that of Hg-vacancy-doped sample which is caused by the deep energy level of the Hg-vacancy acceptor that is considered as a recombination center in HgCdTe. Also we found lifetime in those p-type doped HgCdTe LWIR epilayers is limited by SRH by comparing the experimental lifetimes with the calculated data. Impurity doping was found to have a main effect on minority carrier lifetime.

  5. Organic light emitting diodes with environmentally and thermally stable doped graphene electrodes

    DEFF Research Database (Denmark)

    Kuruvila, Arun; Kidambi, Piran R.; Kling, Jens

    2014-01-01

    We present a comparative study of the environmental and thermal stability of graphene charge transfer doping using molybdenum– trioxide (MoO3), vanadium–pentoxide (V2O5) and tungsten–trioxide (WO3). Our results show that all these metal oxides allow a strong and stable p-type doping of graphene...

  6. ZnO-based semiconductors studied by Raman spectroscopy. Semimagnetic alloying, doping, and nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Schumm, Marcel

    2009-07-01

    ZnO-based semiconductors were studied by Raman spectroscopy and complementary methods (e.g. XRD, EPS) with focus on semimagnetic alloying with transition metal ions, doping (especially p-type doping with nitrogen as acceptor), and nanostructures (especially wet-chemically synthesized nanoparticles). (orig.)

  7. Effects of Germanium on Movement of Dislocations in p-Type Czochralski Silicon

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    By indentation at room temperature followed by annealing at high temperatures, the pinning effect of germanium on dislocations in germanium-doped Czochralski silicon was investigated. Experimental results show that the dislocations in germanium-doped Czochralski silicon move shorter and slower than those in Czochralski silicon undoping with germanium when the concentration of germanium is over 1×1018 cm-3. The retarding velocity of dislocations is contributed to the dislocations pinning effect of the strain field introduced by the high concentration germanium, and the Ge4B cluster and the oxygen precipitation those are preferred to form at higher concentration germanium.

  8. Low specific contact resistance on epitaxial p-type 4H-SiC with a step-bunching surface

    Science.gov (United States)

    Han, Chao; Zhang, Yu-Ming; Song, Qing-Wen; Tang, Xiao-Yan; Zhang, Yi-Men; Guo, Hui; Wang, Yue-Hu

    2015-11-01

    This paper reports the performances of Ti/Al based ohmic contacts fabricated on highly doped p-type 4H-SiC epitaxial layer which has a severe step-bunching surface. Different contact schemes are investigated based on the Al:Ti composition with no more than 50 at.% Al. The specific contact resistance (SCR) is obtained to be as low as 2.6 × 10-6 Ω·cm2 for the bilayered Ti(100 nm)/Al(100 nm) contact treated with 3 min rapid thermal annealing (RTA) at 1000 °C. The microstructure analyses examined by physical and chemical characterization techniques reveal an alloy-assisted ohmic contact formation mechanism, i.e., a high degree of alloying plays a decisive role in forming the interfacial ternary Ti3SiC2 dominating the ohmic behavior of the Ti/Al based contact. Furthermore, a globally covered Ti3SiC2 layer with (0001)-oriented texture can be formed, regardless of the surface step bunching as well as its structural evolution during the metallization annealing. Project supported by the Key Specific Projects of Ministry of Education of China (Grant No. 625010101), the National Natural Science Foundation of China (Grant No. 61234006), the Natural Science Foundation of ShaanXi Province, China (Grant No. 2013JQ8012), the Doctoral Fund of Ministry of Education of China (Grant No. 20130203120017), and the Specific Project of the Core Devices, China (Grant No. 2013ZX0100100-004).

  9. Effective field theory and Ab-initio calculation of p-type (Ga, Fe)N within LDA and SIC approximation

    Science.gov (United States)

    Salmani, E.; Mounkachi, O.; Ez-Zahraouy, H.; El Kenz, A.; Hamedoun, M.; Benyoussef, A.

    2013-03-01

    Based on first-principles spin-density functional calculations, using the Korringa-Kohn-Rostoker method combined with the coherent potential approximation, we investigated the half-metallic ferromagnetic behavior of (Ga, Fe)N co-doped with carbon within the self-interaction-corrected local density approximation. Mechanism of hybridization and interaction between magnetic ions in p-type (Ga, Fe)N is investigated. Stability energy of ferromagnetic and disorder local moment states was calculated for different carbon concentration. The local density and the self-interaction-corrected approximations have been used to explain the strong ferromagnetic interaction observed and the mechanism that stabilizes this state. The transition temperature to the ferromagnetic state has been calculated within the effective field theory, with a Honmura-Kaneyoshi differential operator technique.

  10. 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.

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

    Directory of Open Access Journals (Sweden)

    Chun-You Wei

    2013-11-01

    Full Text Available 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.

  12. Comment on 'Electronic Properties of Red P-Type T12S5 Single Crystals'

    Institute of Scientific and Technical Information of China (English)

    M. Cankurtaran; H. (C)elik

    2007-01-01

    Recently, Gamal et al. [Chin. Phys. Lett. 22 (2005) 1530] reported the results of electrical conductivity, Hall effect and thermoelectric measurements on p-type Th2S5 single crystals. From the experimental data for the temperature dependence of differential thermoelectric power, Gamal et al. determined the values of 2.66 × 10-41 kg and 2.50 × 10-41 kg, respectively, for the effective masses of electrons and holes in p-type Tl2S5, which are about ten orders of magnitude smaller than the free electron mass (9.11 × 10-31 kg). We argue that the anomalously small values obtained for the effective mass of charge carriers in Tl2S5 have no physical significance.

  13. An integrated driving circuit implemented with p-type LTPS TFTs for AMOLED

    Institute of Scientific and Technical Information of China (English)

    ZHAO Li-qing; WU Chun-ya; HAO Da-shou; YAO Ying; MENG Zhi-guo; XIONG Shao-zhen

    2009-01-01

    Based on the technology of low temperature poly silicon thin film transistors (poly-Si-TFTs), a novel p-type TFT AMOLED panel with self-scanned driving circuit is introduced in this paper. A shift register formed with novel p-type TFTs is pro-posed to realize the gate driver. A flip-latch cooperated with the shift register is designed to conduct the data writing. In order to verify the validity of the proposed design, the circuits are simulated with SILVACO TCAD tools, using the MODEL in which the parameters of LTPS TFTs were extracted from the LTPS TFTs made in our lab. The simulation results indicate that the circuit can fulfill the driving function.

  14. Measurement of the dead layer thickness in a p-type point contact germanium detector

    Science.gov (United States)

    Jiang, Hao; Yue, Qian; Li, Yu-Lan; Kang, Ke-Jun; Li, Yuan-Jing; Li, Jin; Lin, Shin-Ted; Liu, Shu-Kui; Ma, Hao; Ma, Jing-Lu; Su, Jian; Tsz-King Wong, Henry; Yang, Li-Tao; Zhao, Wei; Zeng, Zhi

    2016-09-01

    A 994 g mass p-type PCGe detector has been deployed during the first phase of the China Dark matter EXperiment, aiming at direct searches for light weakly interacting massive particles. Measuring the thickness of the dead layer of a p-type germanium detector is an issue of major importance since it determines the fiducial mass of the detector. This work reports a method using an uncollimated 133Ba source to determine the dead layer thickness. The experimental design, data analysis and Monte Carlo simulation processes, as well as the statistical and systematic uncertainties are described. A dead layer thickness of 1.02 mm was obtained based on a comparison between the experimental data and the simulated results. Supported by National Natural Science Foundation of China (10935005, 10945002, 11275107, 11175099)

  15. Preparation and Photovoltaic Properties of p-Type Nano-ZnFe2O4

    Institute of Scientific and Technical Information of China (English)

    LI Zi-heng; ZOU Xu; LI Gen; ZOU Guang-tian

    2012-01-01

    p-Type nano-ZnFe2O4 semiconductors were gained by high-prssure treatment.Surface photovoltaic spectrum(SPS) and transient photovoltaic technology(TPV) were used for studying the photogenerated charge of nano-ZnFe2O4.Results show that the photovoltaic behavior of nano-ZnFe2O4 changed as the processing pressure increased.When the processing pressure was higher than 2 GPa,both SPS response interval and peak changed significantly.XPS results show that the non-lattice oxygen entered into the lattice and the content of lattice oxygen increased with the increase of processing pressure.The material changed from oxygen vacancy type to oxygen excess type and the photoelectric properties changed from n-type to p-type when the processing pressure is higher than 2GPa.

  16. 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...... 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...

  17. Perspectives of High-Temperature Thermoelectric Applications and p-type and n-type Aluminoborides

    Science.gov (United States)

    Mori, T.

    2016-10-01

    A need exists to develop high-temperature thermoelectric materials which can utilize high-temperature unutilized/waste heat in thermal power plants, steelworks, factories, incinerators, etc., and also focused solar power. The thermal power plant topping application is of potential high impact since it can sizably increase the efficiency of power plants which are the major supply of electrical power for many countries. Higher borides are possible candidates for their particular high-temperature stability, generally large Seebeck coefficients, α, and intrinsic low thermal conductivity. Excellent (|α| > 200 μV/K) p-type or n-type behavior was recently achieved in the aluminoboride YAl x B14 by varying the occupancy of Al sites, x. Finding p-type and n-type counterparts has long been a difficulty of thermoelectric research not limited to borides. This paper reviews possible high-temperature thermoelectric applications, and recent developments and perspectives of thermoelectric aluminoborides.

  18. 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.

  19. Sensitization of p-type NiO using n-type conducting polymers

    NARCIS (Netherlands)

    Chavhan, S.D.; Abellon, R.D.; Breemen, A.J.J.M. van; Koetse, M.M.; Sweelssen, J.; Savenije, T.J.

    2010-01-01

    We report on the sensitization of a p-type inorganic semiconductor, NiO, by n-type conjugated polymers. NiO thin films were deposited using RF sputtering in pure Ar (NiO A) or in Ar + O2 (90% + 10%) (NiO B). XPS and Kelvin probe measurements indicate the incorporation of oxygen in NiO B

  20. Sensitization of p-type NiO using n-type conducting polymers

    NARCIS (Netherlands)

    Chavhan, S.D.; Abellon, R.D.; Breemen, A.J.J.M. van; Koetse, M.M.; Sweelssen, J.; Savenije, T.J.

    2010-01-01

    We report on the sensitization of a p-type inorganic semiconductor, NiO, by n-type conjugated polymers. NiO thin films were deposited using RF sputtering in pure Ar (NiO A) or in Ar + O2 (90% + 10%) (NiO B). XPS and Kelvin probe measurements indicate the incorporation of oxygen in NiO B l

  1. Investigation of negative photoconductivity in p-type Pb1-xSnxTe film

    Science.gov (United States)

    Tavares, M. A. B.; da Silva, M. J.; Peres, M. L.; de Castro, S.; Soares, D. A. W.; Okazaki, A. K.; Fornari, C. I.; Rappl, P. H. O.; Abramof, E.

    2017-01-01

    We investigated the negative photoconductivity (NPC) effect that was observed in a p-type Pb1-xSnxTe film for temperatures varying from 300 K down to 85 K. We found that this effect is a consequence of defect states located in the bandgap which act as trapping levels, changing the relation between generation and recombination rates. Theoretical calculations predict contributions to the NPC from both conduction and valence bands, which are in accordance with the experimental observations.

  2. Sensitization of p-type NiO using n-type conducting polymers

    NARCIS (Netherlands)

    Chavhan, S.D.; Abellon, R.D.; Breemen, A.J.J.M. van; Koetse, M.M.; Sweelssen, J.; Savenije, T.J.

    2010-01-01

    We report on the sensitization of a p-type inorganic semiconductor, NiO, by n-type conjugated polymers. NiO thin films were deposited using RF sputtering in pure Ar (NiO A) or in Ar + O2 (90% + 10%) (NiO B). XPS and Kelvin probe measurements indicate the incorporation of oxygen in NiO B l

  3. Radiation damage studies of multi-guard ring p-type bulk diodes

    CERN Document Server

    Bortoletto, D; Günther, M; Grim, G P; Lander, R L; Willard, S; Li, Z

    1999-01-01

    Several diodes with different multi-guard ring structures were fabricated from 10 k OMEGA cm p-type bulk material. Studies on the performance of such devices are presented here. They include the measurement of the leakage current, breakdown voltage and charge collection efficiency before and after 2x10 sup 1 sup 4 p/cm sup 2 irradiation with 63.3 MeV kinetic protons. (author)

  4. Kinetics of self-interstitials reactions in p-type silicon irradiated with alpha particles

    Energy Technology Data Exchange (ETDEWEB)

    Makarenko, L.F., E-mail: makarenko@bsu.by [Department of Applied Mathematics and Computer Science, Belarusian State University, Independence Ave. 4, 220030 Minsk (Belarus); Moll, M. [CERN, Geneva (Switzerland); Evans-Freeman, J.H. [University of Canterbury, Christchurch (New Zealand); Lastovski, S.B.; Murin, L.I.; Korshunov, F.P. [Scientific-Practical Materials Research Centre of NAS of Belarus, Minsk (Belarus)

    2012-08-01

    New findings on the self-interstitial migration in p-type silicon are presented. They are based on experimental studies of the formation kinetics of defects related to interstitial carbon after irradiation with alpha particles. The main parameters characterizing the interaction rate of silicon self-interstitials with substitutional carbon atoms have been determined. A preliminary interpretation of the experimental data is given. The interpretation takes into account different diffusivities of self-interstitials in their singly and doubly ionized states.

  5. Biomarker monitoring in sports doping control.

    Science.gov (United States)

    Pottgiesser, Torben; Schumacher, Yorck Olaf

    2012-06-01

    Biomarker monitoring can be considered a new era in the effort against doping. Opposed to the old concept in doping control of direct detection of a prohibited substance in a biological sample such as urine or blood, the new paradigm allows a personalized longitudinal monitoring of biomarkers that indicate non-physiological responses independently of the used doping technique or substance, and may cause sanctioning of illicit practices. This review presents the development of biomarker monitoring in sports doping control and focuses on the implementation of the Athlete Biological Passport as the current concept of the World Anti Doping Agency for the detection of blood doping (hematological module). The scope of the article extends to the description of novel biomarkers and future concepts of application.

  6. Performance and stress analysis of oxide thermoelectric module architecture designed for maximum power output

    DEFF Research Database (Denmark)

    Wijesekara, Waruna; Rosendahl, Lasse; Wu, NingYu;

    Oxide thermoelectric materials are promising candidates for energy harvesting from mid to high temperature heat sources. In this work, the oxide thermoelectric materials and the final design of the high temperature thermoelectric module were developed. Also, prototypes of oxide thermoelectric...... generator were built for high temperature applications. This paper specifically discusses the thermoelectric module design and the prototype validations of the design. Here p type calcium cobalt oxide and n type aluminum doped ZnO were developed as the oxide thermoelectric materials. Hot side and cold side...... temperatures were used as 1100 K and 400 K respectively. Using analytical methods, the optimum thermoelement length and the thermoelements area ratio were explored in order to provide the maximum power output by the uni-couple and it is compared to methods reported in literature. Based on operating conditions...

  7. 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.

  8. Demethoxycurcumin Is A Potent Inhibitor of P-Type ATPases from Diverse Kingdoms of Life.

    Science.gov (United States)

    Dao, Trong Tuan; Sehgal, Pankaj; Tung, Truong Thanh; Møller, Jesper Vuust; Nielsen, John; Palmgren, Michael; Christensen, Søren Brøgger; Fuglsang, Anja Thoe

    2016-01-01

    P-type ATPases catalyze the active transport of cations and phospholipids across biological membranes. Members of this large family are involved in a range of fundamental cellular processes. To date, a substantial number of P-type ATPase inhibitors have been characterized, some of which are used as drugs. In this work a library of natural compounds was screened and we first identified curcuminoids as plasma membrane H+-ATPases inhibitors in plant and fungal cells. We also found that some of the commercial curcumins contain several curcuminoids. Three of these were purified and, among 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 of these pumps. Future research on biological effects of commercial preparations of curcumin should consider the heterogeneity of the material.

  9. p-Type Quasi-Mono Silicon Solar Cell Fabricated by Ion Implantation

    Directory of Open Access Journals (Sweden)

    Chien-Ming Lee

    2013-01-01

    Full Text Available The p-type quasi-mono wafer is a novel type of silicon material that is processed using a seed directional solidification technique. This material is a promising alternative to traditional high-cost Czochralski (CZ and float-zone (FZ material. Here, we evaluate the application of an advanced solar cell process featuring a novel method of ion implantation on p-type quasi-mono silicon wafer. The ion implantation process has simplified the normal industrial process flow by eliminating two process steps: the removal of phosphosilicate glass (PSG and the junction isolation process that is required after the conventional thermal POCl3 diffusion process. Moreover, the good passivation performance of the ion implantation process improves Voc. Our results show that, after metallization and cofiring, an average cell efficiency of 18.55% can be achieved using 156 × 156 mm p-type quasi-mono silicon wafer. Furthermore, the absolute cell efficiency obtained using this method is 0.47% higher than that for the traditional POCl3 diffusion process.

  10. Enhanced thermopower and low thermal conductivity in p-type polycrystalline ZrTe5

    Science.gov (United States)

    Hooda, M. K.; Yadav, C. S.

    2017-07-01

    Thermoelectric properties of polycrystalline p-type ZrTe5 are reported in the temperature (T) range of 2-340 K. Thermoelectric power (S) is positive and reaches up to 458 μV/K at 340 K on increasing T. The value of Fermi energy 16 meV suggests a low carrier density of ≈9.5 × 1018 cm-3. A sharp anomaly in S data is observed at 38 K, which seems intrinsic to p-type ZrTe5. The thermal conductivity (κ) value is low (2 W/m K at T = 300 K) with major contribution from the lattice part. Electrical resistivity data show the metal to semiconductor transition at T ˜ 150 K and non-Arrhenius behavior in the semiconducting region. The figure of merit zT (0.026 at T = 300 K) is ˜63% higher than that of HfTe5 (0.016) and better than those of the conventional SnTe, p-type PbTe, and bipolar pristine ZrTe5 compounds.

  11. Efficient synthesis of triarylamine-based dyes for p-type dye-sensitized solar cells

    Science.gov (United States)

    Wild, Martin; Griebel, Jan; Hajduk, Anna; Friedrich, Dirk; Stark, Annegret; Abel, Bernd; Siefermann, Katrin R.

    2016-05-01

    The class of triarylamine-based dyes has proven great potential as efficient light absorbers in inverse (p-type) dye sensitized solar cells (DSSCs). However, detailed investigation and further improvement of p-type DSSCs is strongly hindered by the fact that available synthesis routes of triarylamine-based dyes are inefficient and particularly demanding with regard to time and costs. Here, we report on an efficient synthesis strategy for triarylamine-based dyes for p-type DSSCs. A protocol for the synthesis of the dye-precursor (4-(bis(4-bromophenyl)amino)benzoic acid) is presented along with its X-ray crystal structure. The dye precursor is obtained from the commercially available 4(diphenylamino)benzaldehyde in a yield of 87% and serves as a starting point for the synthesis of various triarylamine-based dyes. Starting from the precursor we further describe a synthesis protocol for the dye 4-{bis[4‧-(2,2-dicyanovinyl)-[1,1‧-biphenyl]-4-yl]amino}benzoic acid (also known as dye P4) in a yield of 74%. All synthesis steps are characterized by high yields and high purities without the need for laborious purification steps and thus fulfill essential requirements for scale-up.

  12. Modulated two-dimensional charge-carrier density in LaTiO3-layer-doped LaAlO3/SrTiO3 heterostructure.

    Science.gov (United States)

    Nazir, Safdar; Bernal, Camille; Yang, Kesong

    2015-03-11

    The highly mobile two-dimensional electron gas (2DEG) formed at the polar/nonpolar LaAlO3/SrTiO3 (LAO/STO) heterostructure (HS) is a matter of great interest because of its potential applications in nanoscale solid-state devices. To realize practical implementation of the 2DEG in device design, desired physical properties such as tuned charge carrier density and mobility are necessary. In this regard, polar perovskite-based transition metal oxides can act as doping layers at the interface and are expected to tune the electronic properties of 2DEG of STO-based HS systems dramatically. Herein, we investigated the doping effects of LaTiO3(LTO) layers on the electronic properties of 2DEG at n-type (LaO)(+1)/(TiO2)(0) interface in the LAO/STO HS using spin-polarized density functional theory calculations. Our results indicate an enhancement of orbital occupation near the Fermi energy, which increases with respect to the number of LTO unit cells, resulting in a higher charge carrier density of 2DEG than that of undoped system. The enhanced charge carrier density is attributed to an extra electron introduced by the Ti 3d(1) orbitals from the LTO dopant unit cells. This conclusion is consistent with the recent experimental findings (Appl. Phys. Lett. 2013, 102, 091601). Detailed charge density and partial density of states analysis suggests that the 2DEG in the LTO-doped HS systems primarily comes from partially occupied dyz and dxz orbitals.

  13. Observation of As-Grown Defects in Zn-Doped GaAs by Positron Lifetime Spectra

    Institute of Scientific and Technical Information of China (English)

    WANG Zhu; WANG Shao-Jie; CHEN Zhi-Quan

    2000-01-01

    Positron lifetime spectra were measured for the Zn-doped p-type GaAs. In comparing the horizontal-Bridgman-method-grown and the floating-zone-method grown p-type GaAs with the liquid-encapsulation-Czochvalski-grown p-type GaAs samples, positron trapping into vacancy type defects was observed in the former two grown p-type GaAs. Shallow positron traps were detected, and the dominant ones were attributed to acceptor the in p-type GaAs.

  14. Effects of Mg Doping on Photoconductivity of GaN Films

    Institute of Scientific and Technical Information of China (English)

    Deheng ZHANG; Qingpu WANG; Yunyan LIU

    2003-01-01

    This paper presents the UV photoconductivity properties of GaN films doped with different Mg concentrations deposited by MOCVD. It was observed that for the undoped and weakly doped GaN films the UV photocurrent response was relatively large and the relax time was relatively short. With an increase in doped Mg content, the samples became p-type, the photocurrent response became weak and the relax time became longer.

  15. P-type Cu--Ti--O nanotube arrays and their use in self-biased heterojunction photoelectrochemical diodes for hydrogen generation.

    Science.gov (United States)

    Mor, Gopal K; Varghese, Oomman K; Wilke, Rudeger H T; Sharma, Sanjeev; Shankar, Karthik; Latempa, Thomas J; Choi, Kyoung-Shin; Grimes, Craig A

    2008-07-01

    Copper and titanium remain relatively plentiful in the earth's crust; hence, their use for large-scale solar energy conversion technologies is of significant interest. We describe fabrication of vertically oriented p-type Cu-Ti-O nanotube array films by anodization of copper rich (60% to 74%) Ti metal films cosputtered onto fluorine doped tin oxide (FTO) coated glass. Cu-Ti-O nanotube array films 1 mum thick exhibit external quantum efficiencies up to 11%, with a spectral photoresponse indicating that the complete visible spectrum, 380 to 885 nm, contributes significantly to the photocurrent generation. Water-splitting photoelectrochemical pn-junction diodes are fabricated using p-type Cu-Ti-O nanotube array films in combination with n-type TiO 2 nanotube array films. With the glass substrates oriented back-to-back, light is incident upon the UV absorbing n-TiO 2 side, with the visible light passing to the p-Cu-Ti-O side. In a manner analogous to photosynthesis, photocatalytic reactions are powered only by the incident light to generate fuel with oxygen evolved from the n-TiO 2 side of the diode and hydrogen from the p-Cu-Ti-O side. To date, we find under global AM 1.5 illumination that such photocorrosion-stable diodes generate a photocurrent of approximately 0.25 mA/cm (2), at a photoconversion efficiency of 0.30%.

  16. Chemical Bath Deposition of p-Type Transparent, Highly Conducting (CuS)x:(ZnS)1-x Nanocomposite Thin Films and Fabrication of Si Heterojunction Solar Cells.

    Science.gov (United States)

    Xu, Xiaojie; Bullock, James; Schelhas, Laura T; Stutz, Elias Z; Fonseca, Jose J; Hettick, Mark; Pool, Vanessa L; Tai, Kong Fai; Toney, Michael F; Fang, Xiaosheng; Javey, Ali; Wong, Lydia Helena; Ager, Joel W

    2016-03-09

    P-type transparent conducting films of nanocrystalline (CuS)x:(ZnS)1-x were synthesized by facile and low-cost chemical bath deposition. Wide angle X-ray scattering (WAXS) and high resolution transmission electron microscopy (HRTEM) were used to evaluate the nanocomposite structure, which consists of sub-5 nm crystallites of sphalerite ZnS and covellite CuS. Film transparency can be controlled by tuning the size of the nanocrystallites, which is achieved by adjusting the concentration of the complexing agent during growth; optimal films have optical transmission above 70% in the visible range of the spectrum. The hole conductivity increases with the fraction of the covellite phase and can be as high as 1000 S cm(-1), which is higher than most reported p-type transparent materials and approaches that of n-type transparent materials such as indium tin oxide (ITO) and aluminum doped zinc oxide (AZO) synthesized at a similar temperature. Heterojunction p-(CuS)x:(ZnS)1-x/n-Si solar cells were fabricated with the nanocomposite film serving as a hole-selective contact. Under 1 sun illumination, an open circuit voltage of 535 mV was observed. This value compares favorably to other emerging heterojunction Si solar cells which use a low temperature process to fabricate the contact, such as single-walled carbon nanotube/Si (370-530 mV) and graphene/Si (360-552 mV).

  17. n- and p-type transport in (110) GaAs substrates, single- and double-cleave structures

    Energy Technology Data Exchange (ETDEWEB)

    Roth, S.F.

    2007-06-06

    In this work low-dimensional systems based on GaAs/AlGaAs are investigated with either holes (p-type) in two-dimensional (2D) systems or electrons (n-type) in one-dimensional (1D) systems as charge carriers. Two-dimensional hole systems (2DHS) are grown with molecular beam epitaxy both on (110) wafers and (1 anti 10) facets with the cleaved-edge overgrowth (CEO) method. We use Si as an acceptor by modulating the growth conditions to fabricate the 2DHS in single-interface heterojunction quantum wells. The mobility of the structures reaches up to 7.0 x 10{sup 5} cm{sup 2}/Vs along the [1 anti 10]-direction and 4.1 x 10{sup 5} cm{sup 2}/Vs along the [001]-direction at a hole density of 1.2 x 10{sup 11} cm{sup -2}. Effective values for anisotropic effective hole masses and scattering times are obtained. Inversion asymmetry induced spin splitting results in different spin densities, which yield beatings of the Shubnikov-de Haas oscillations at low temperatures. In a perpendicular magnetic field the 2DHS is quantized into Landau levels, which depend nonlinearly on B due to a strong mixing of light- and heavy-holes. When the Landau levels anticross on the (110) facet, additional peaks appear within minima of the quantum Hall effect. Thermal activation measurements demonstrate a B-dependent energy gap consistent with such an anticrossing. In the second part of the thesis an electron quantum wire is fabricated with twofold cleaved-edge overgrowth. A variation of the conduction band energy in the substrate layers can directly transfer a potential modulation to the adjacent quantum wire. The concept of a transfer potential applied to a narrow two-dimensional system is demonstrated as a first step. Finally, in narrow quantum well samples a simple vertical quantum wire is successfully demonstrated and contacted at each end with n{sup +}-GaAs layers via two-dimensional (2D) leads. We characterize the 2D lead density and mobility for both cleave facets with four

  18. Studies on electrochemically constructed n- and p-type photoelectrodes for use in solar energy conversion

    Science.gov (United States)

    Kang, Donghyeon

    Among several pathways to harvest solar energy, solar water splitting is one of the most efficient methods to convert solar light to hydrogen, which is a clean and easy to store chemical that has the potential to be used as a fuel source. Solar water splitting can be achieved primarily by photoelectrochemical cells (PECs), which utilize semiconductors as photoelectrodes for the water splitting reaction. Photoelectrodes play the crucial role of generating hydrogen but, to date, very few photoelectrodes have been developed that can produce hydrogen in a stable and efficient manner. Thus, development and modification of efficient, stable photoelectrodes are highly desirable to improve performance of solar water splitting PECs. This dissertation demonstrates the development of semiconductors as photoelectrodes and their modifications to advance solar energy conversion performance by newly established electrochemical synthetic routes. To improve the photoelectrochemical performance of photoelectrodes, various strategies were introduced, such as, morphology control, extrinsic doping, and the integration of catalysts. After successfully demonstrating the electrochemical synthesis of photoelectrodes, photoelectrochemical and electrochemical properties of electrodeposited photoelectrodes in PECs are discussed. The chapters can be categorized into three major themes. The first theme is the preparation of Bi-based photoanodes for the water oxidation reaction. Chapter 2 presents a study of Mo-doping into the BiVO4 photoanode to enhance charge separation properties. After Mo-doping was achieved successfully, a FeOOH oxygen evoltuion catalyst was integrated into the Mo-doped BiVO 4 photoanode to increase the water oxidation performance. Chapter 3 introduces another electrochemical synthesis method to control the morphology of Bi-based oxide photoanode materials. The second theme of this dissertation is the preparation of photocathode materials for the water reduction reaction

  19. Fabrication and characterization of silicon nanowire p-i-n MOS gated diode for use as p-type tunnel FET

    Science.gov (United States)

    Brouzet, V.; Salem, B.; Periwal, P.; Rosaz, G.; Baron, T.; Bassani, F.; Gentile, P.; Ghibaudo, G.

    2015-11-01

    In this paper, we present the fabrication and electrical characterization of a MOS gated diode based on axially doped silicon nanowire (NW) p-i-n junctions. These nanowires are grown by chemical vapour deposition (CVD) using the vapour-liquid-solid (VLS) mechanism. NWs have a length of about 7 \\upmu {m} with 3 \\upmu {m} of doped regions (p-type and n-type) and 1 \\upmu {m} of intrinsic region. The gate stack is composed of 15 nm of hafnium dioxide ({HfO}2), 80 nm of nickel and 120 nm of aluminium. At room temperature, I_{{on}} =-52 {nA}/\\upmu {m} (V_{{DS}}=-0.5 {V}, V_{{GS}}=-4 {V}), and an I_{{on}}/I_{{off}} ratio of about 104 with a very low I_{{off}} current has been obtained. Electrical measurements are carried out between 90 and 390 K, and we show that the I on current is less temperature dependent below 250 K. We also observe that the ON current is increasing between 250 and 390 K. These transfer characteristics at low and high temperature confirm the tunnelling transport mechanisms in our devices.

  20. Free-charge carrier parameters of n-type, p-type and compensated InN:Mg determined by Infrared Spectroscopic Ellipsometry

    CERN Document Server

    Schöche, S; Darakchieva, V; Wang, X; Yoshikawa, A; Wang, K; Araki, T; Nanishi, Y; Schubert, M

    2013-01-01

    Infrared spectroscopic ellipsometry is applied to investigate the free-charge carrier properties of Mg-doped InN films. Two representative sets of In-polar InN grown by molecular beam epitaxy with Mg concentrations ranging from $1.2\\times10^{17}$ cm$^{-3}$ to $8\\times10^{20}$ cm$^{-3}$ are compared. P-type conductivity is indicated for the Mg concentration range of $1\\times10^{18}$ cm$^{-3}$ to $9\\times10^{19}$ cm$^{-3}$ from a systematic investigation of the longitudinal optical phonon plasmon broadening and the mobility parameter in dependence of the Mg concentration. A parameterized model that accounts for the phonon-plasmon coupling is applied to determine the free-charge carrier concentration and mobility parameters in the doped bulk InN layer as well as the GaN template and undoped InN buffer layer for each sample. The free-charge carrier properties in the second sample set are consistent with the results determined in a comprehensive analysis of the first sample set reported earlier [Sch\\"oche et al., ...

  1. 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.

  2. Monolayer MoS2 Nanoribbons as a Promising Material for Both n-type and p-type Legs in Thermoelectric Generators

    Science.gov (United States)

    Arab, A.; Davydov, A. V.; Papaconstantopoulos, D. A.; Li, Q.

    2016-10-01

    First-principles calculations have been performed to study the thermoelectric properties of monolayer MoS2 armchair nanoribbons (ACNRs). The electronic behavior of nanoribbons is dominated by the presence of edge states that are dependent on the number of zigzag chains across the nanoribbon. In addition, it is found that the phonon thermal conductance of monolayer MoS2 ACNRs is smaller than monolayer films due to phonon edge scattering. This effect is more pronounced in narrower nanoribbons, which leads to a higher ZT value compared to a monolayer MoS2 sheet. The effects of sulfur vacancy and edge roughness on the thermoelectric properties of MoS2 ACNRs have also been studied. We found that edge roughness decreased ZT values compared to those of perfect nanoribbons, as its impact on electrical conductance is more severe than on phonon thermal conductance. Sulfur vacancy, however, improved ZT in some subbands. It is shown that ZT values as high as 4 for electron-doped and 3 for hole-doped nanoribbons can be achieved at T = 500 K. The ability to achieve high ZT values for both p-type and n-type nanoribbons makes monolayer MoS2 ACNR a promising candidate for future solid-state thermoelectric generators.

  3. Hopping conduction in p-type MoS{sub 2} near the critical regime of the metal-insulator transition

    Energy Technology Data Exchange (ETDEWEB)

    Park, Tae-Eon; Jang, Chaun, E-mail: cujang@kist.re.kr, E-mail: presto@kist.re.kr [Center for Spintronics, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Suh, Joonki; Wu, Junqiao [Department of Materials Science and Engineering, University of California, Berkeley, California 94720 (United States); Seo, Dongjea [Center for Spintronics, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Park, Joonsuk [Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States); Lin, Der-Yuh [Department of Electronics Engineering, National Changhua University of Education, Changhua 50007, Taiwan (China); Huang, Ying-Sheng [Department of Electronics Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Choi, Heon-Jin [Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Chang, Joonyeon, E-mail: cujang@kist.re.kr, E-mail: presto@kist.re.kr [Center for Spintronics, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Department of Nanomaterials Science and Engineering, Korea University of Science and Technology, Daejeon 305-350 (Korea, Republic of)

    2015-11-30

    We report on temperature-dependent charge and magneto transport of chemically doped MoS{sub 2}, p-type molybdenum disulfide degenerately doped with niobium (MoS{sub 2}:Nb). The temperature dependence of the electrical resistivity is characterized by a power law, ρ(T) ∼ T{sup −0.25}, which indicates that the system resides within the critical regime of the metal-insulator (M-I) transition. By applying high magnetic field (∼7 T), we observed a 20% increase in the resistivity at 2 K. The positive magnetoresistance shows that charge transport in this system is governed by the Mott-like three-dimensional variable range hopping (VRH) at low temperatures. According to relationship between magnetic-field and temperature dependencies of VRH resistivity, we extracted a characteristic localization length of 19.8 nm for MoS{sub 2}:Nb on the insulating side of the M-I transition.

  4. Magnetism in 3d transition metal doped SnO

    KAUST Repository

    Albar, Arwa

    2016-09-12

    Using first principles calculations, we investigate the structural and electronic properties of 3d transition metal doped SnO. We examine the stability of different doping sites using formation energy calculations. The magnetic behavior of the dopant atoms is found to be complex because of interplay between strong structural relaxation, spin-lattice coupling, and crystal field splitting. The interaction between dopant atoms is analyzed as a function of their separation, showing that clustering typically counteracts spin polarization. An exception is found for V doping, which thus turns out to be a promising candidate for realizing a magnetic p-type oxide.

  5. Doping Silicon Wafers with Boron by Use of Silicon Paste

    Institute of Scientific and Technical Information of China (English)

    Yu Gao; Shu Zhou; Yunfan Zhang; Chen Dong; Xiaodong Pi; Deren Yang

    2013-01-01

    In this work we introduce recently developed silicon-paste-enabled p-type doping for silicon.Boron-doped silicon nanoparticles are synthesized by a plasma approach.They are then dispersed in solvents to form silicon paste.Silicon paste is screen-printed at the surface of silicon wafers.By annealing,boron atoms in silicon paste diffuse into silicon wafers.Chemical analysis is employed to obtain the concentrations of boron in silicon nanoparticles.The successful doping of silicon wafers with boron is evidenced by secondary ion mass spectroscopy (SIMS) and sheet resistance measurements.

  6. Effect of indium and antimony doping in SnS single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Chaki, Sunil H., E-mail: sunilchaki@yahoo.co.in; Chaudhary, Mahesh D.; Deshpande, M.P.

    2015-03-15

    Highlights: • Single crystals growth of pure SnS, indium doped SnS and antimony doped SnS by direct vapour transport (DVT) technique. • Doping of In and Sb occurred in SnS single crystals by cation replacement. • The replacement mechanism ascertained by EDAX, XRD and substantiated by Raman spectra analysis. • Dopants concentration affects the optical energy bandgap. • Doping influences electrical transport properties. - Abstract: Single crystals of pure SnS, indium (In) doped SnS and antimony (Sb) doped SnS were grown by direct vapour transport (DVT) technique. Two doping concentrations of 5% and 15% each were employed for both In and Sb dopants. Thus in total five samples were studied viz., pure SnS (S1), 5% In doped SnS (S2), 15% In doped SnS (S3), 5% Sb doped SnS (S4) and 15% Sb doped SnS (S5). The grown single crystal samples were characterized by evaluating their surface microstructure, stoichiometric composition, crystal structure, Raman spectroscopy, optical and electrical transport properties using appropriate techniques. The d.c. electrical resistivity and thermoelectric power variations with temperature showed semiconducting and p-type nature of the as-grown single crystal samples. The room temperature Hall Effect measurements further substantiated the semiconducting and p-type nature of the as-grown single crystal samples. The obtained results are deliberated in detail.

  7. Ivermectin is a nonselective inhibitor of mammalian P-type ATPases.

    Science.gov (United States)

    Pimenta, Paulo Henrique Cotrim; Silva, Claudia Lucia Martins; Noël, François

    2010-02-01

    Ivermectin is a large spectrum antiparasitic drug that is very safe at the doses actually used. However, as it is being studied for new applications that would require higher doses, we should pay attention to its effects at high concentrations. As micromolar concentrations of ivermectin have been reported to inhibit the sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA), we decided to investigate its putative inhibitory effect on other two important P-type ATPases, namely the Na(+) , K(+)-ATPase and H(+)/K(+)-ATPase. We first extended the data on SERCA, using preparations from rat enriched in SERCA1a (extensor digitorum longus) and 1b (heart) isoforms. Secondly, we tested the effect of ivermectin in two preparations of rat Na(+), K(+)-ATPase in order to appreciate its putative selectivity towards the alpha(1) isoform (kidney) and the alpha(2)/alpha(3) isoforms (brain), and in an H(+)/K(+)-ATPase preparation from rat stomach. Ivermectin inhibited all these ATPases with similar IC(50) values (6-17 microM). With respect to the inhibition of the Na(+), K(+)-ATPase, ivermectin acts by a mechanism different from the classical cardiac glycosides, based on selectivity towards the isoforms, sensibility to the antagonistic effect of K(+) and to ionic conditions favoring different conformations of the enzyme. We conclude that ivermectin is a nonselective inhibitor of three important mammalian P-type ATPases, which is indicative of putative important adverse effects if this drug were used at high doses. As a consequence, we propose that novel analogs of ivermectin should be developed and tested both for their parasitic activity and in vitro effects on P-type ATPases.

  8. Enhanced photovoltaic effect of ruthenium complex-modified graphene oxide with P-type conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei, E-mail: jj_zw_js@sina.com.cn; Bai, Huicong; Zhang, Yu; Sun, Ying; Lin, Shen; Liu, Jian; Yang, Qi; Song, Xi-Ming, E-mail: songlab@lnu.edu.cn

    2014-10-15

    A graphene oxide nanocomposite with bis(1,10-phenanthroline)(N-(2-aminoethyl)-4-(4-methyl-2,2-bipyridine-4-yl) formamide) ruthenium (Ru(phen){sub 2}(bpy-NH{sub 2})(PF{sub 6}){sub 2}), a ruthenium complex, was synthesized by amidation reaction between amino group of the ruthenium complex and carboxyl group of GO. The as-prepared Ru(II)–GO composite was characterized by infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), ultraviolet–visible (UV–Vis) absorption spectra, fluorescence spectra, surface photovoltage (SPV) spectrum and transient photovoltage (TPV) technology. This nanocomposite showed a typical p-type character and an enhanced photovoltaic effect at long timescale of about 3 × 10{sup −3} s compared to GO alone. A reversible rise/decay of the photocurrent in response to the on/off illumination step was also observed in a photoelectrochemical cell of the Ru(II)–GO composite. The photocurrent response of the Ru(II)–GO film was remarkably higher than that of GO film. Therefore, this Ru(II)–GO composite is believed to be a promising p-type photoelectric conversion material for further photovoltaic applications. - Highlights: • A new dye-sensitized graphene oxide nanocomposite was reported. • A photo-induced charge transfer process in this nanocomposite was confirmed. • This composite showed a typical p-type conductivity. • This composite showed an enhanced photovoltaic effect at a long timescale.

  9. Ultrasonic study of point defects in electron-irradiated p-type silicon

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, W.L.

    1987-01-01

    The mechanisms of interaction of ultrasonic waves with point defects in crystals are reviewed, and a perturbation approach is introduced that leads to general expressions for the resonance and relaxation strengths in terms of matrix elements of the ultrasonic perturbation. These expressions provide the basis for a discussion of the polarization dependence of resonance and relaxation. Selection rules for cubic crystals are presented. An exploratory ultrasonic study is performed on electron-irradiated B-doped and Al-doped silicon. Neutral substitutional boron is detected before irradiation, as expected from previous ultrasonic studies on unirradiated silicon. This defect produces both resonance and relaxation. Similar effects are observed for substitutional aluminum. After irradiation, a relaxation is observed when the sample is exposed to 0.18-0.39 eV light. By comparison with previous EPR results, this relaxation is identified as the singly positively charged state of the vacancy, V/sup +/. Preliminary results on the relaxation time and strength of V/sup +/ suggest that it may have several populated vibronic levels. Another relaxation is observed in irradiated Al-doped silicon when the sample is exposed to white light. From its annealing behavior and dopant dependence, it is identified as a nonequilibrium charge state of interstitial aluminum.

  10. 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.

  11. Does p-type ohmic contact exist in WSe2-metal interfaces?

    Science.gov (United States)

    Wang, Yangyang; Yang, Ruo Xi; Quhe, Ruge; Zhong, Hongxia; Cong, Linxiao; Ye, Meng; Ni, Zeyuan; Song, Zhigang; Yang, Jinbo; Shi, Junjie; Li, Ju; Lu, Jing

    2015-12-01

    Formation of low-resistance metal contacts is the biggest challenge that masks the intrinsic exceptional electronic properties of two dimensional WSe2 devices. We present the first comparative study of the interfacial properties between monolayer/bilayer (ML/BL) WSe2 and Sc, Al, Ag, Au, Pd, and Pt contacts by using ab initio energy band calculations with inclusion of the spin-orbital coupling (SOC) effects and quantum transport simulations. The interlayer coupling tends to reduce both the electron and hole Schottky barrier heights (SBHs) and alters the polarity for the WSe2-Au contact, while the SOC chiefly reduces the hole SBH. In the absence of the SOC, the Pd contact has the smallest hole SBH. Dramatically, the Pt contact surpasses the Pd contact and becomes the p-type ohmic or quasi-ohmic contact with inclusion of the SOC. Therefore, p-type ohmic or quasi-ohmic contact exists in WSe2-metal interfaces. Our study provides a theoretical foundation for the selection of favorable metal electrodes in ML/BL WSe2 devices.Formation of low-resistance metal contacts is the biggest challenge that masks the intrinsic exceptional electronic properties of two dimensional WSe2 devices. We present the first comparative study of the interfacial properties between monolayer/bilayer (ML/BL) WSe2 and Sc, Al, Ag, Au, Pd, and Pt contacts by using ab initio energy band calculations with inclusion of the spin-orbital coupling (SOC) effects and quantum transport simulations. The interlayer coupling tends to reduce both the electron and hole Schottky barrier heights (SBHs) and alters the polarity for the WSe2-Au contact, while the SOC chiefly reduces the hole SBH. In the absence of the SOC, the Pd contact has the smallest hole SBH. Dramatically, the Pt contact surpasses the Pd contact and becomes the p-type ohmic or quasi-ohmic contact with inclusion of the SOC. Therefore, p-type ohmic or quasi-ohmic contact exists in WSe2-metal interfaces. Our study provides a theoretical foundation for

  12. 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.

  13. 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....... The structures reveal a similar fold to Cu+-ATPases, with an amphipathic helix at the membrane interface. A conserved electronegative funnel connects this region to the intramembranous high-affinity ion-binding site and may promote specific uptake of cellular Zn2+ ions by the transporter. The E2P structure...

  14. P-Type Silicon Strip Sensors for the new CMS Tracker at HL-LHC

    Science.gov (United States)

    Adam, W.; Bergauer, T.; Brondolin, E.; Dragicevic, M.; Friedl, M.; Frühwirth, R.; Hoch, M.; Hrubec, J.; König, A.; Steininger, H.; Waltenberger, W.; Alderweireldt, S.; Beaumont, W.; Janssen, X.; Lauwers, J.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Beghin, D.; Brun, H.; Clerbaux, B.; Delannoy, H.; De Lentdecker, G.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Karapostoli, G.; Lenzi, Th.; Léonard, A.; Luetic, J.; Postiau, N.; Seva, T.; Vanlaer, P.; Vannerom, D.; Wang, Q.; Zhang, F.; Abu Zeid, S.; Blekman, F.; De Bruyn, I.; De Clercq, J.; D'Hondt, J.; Deroover, K.; Lowette, S.; Moortgat, S.; Moreels, L.; Python, Q.; Skovpen, K.; Van Mulders, P.; Van Parijs, I.; Bakhshiansohi, H.; Bondu, O.; Brochet, S.; Bruno, G.; Caudron, A.; Delaere, C.; Delcourt, M.; De Visscher, S.; Francois, B.; Giammanco, A.; Jafari, A.; Komm, M.; Krintiras, G.; Lemaitre, V.; Magitteri, A.; Mertens, A.; Michotte, D.; Musich, M.; Piotrzkowski, K.; Quertenmont, L.; Szilasi, N.; Vidal Marono, M.; Wertz, S.; Beliy, N.; Caebergs, T.; Daubie, E.; Hammad, G. H.; Härkönen, J.; Lampén, T.; Luukka, P.; Peltola, T.; Tuominen, E.; Tuovinen, E.; Eerola, P.; Tuuva, T.; Baulieu, G.; Boudoul, G.; Caponetto, L.; Combaret, C.; Contardo, D.; Dupasquier, T.; Gallbit, G.; Lumb, N.; Mirabito, L.; Perries, S.; Vander Donckt, M.; Viret, S.; Agram, J.-L.; Andrea, J.; Bloch, D.; Bonnin, C.; Brom, J.-M.; Chabert, E.; Chanon, N.; Charles, L.; Conte, E.; Fontaine, J.-Ch.; Gross, L.; Hosselet, J.; Jansova, M.; Tromson, D.; Autermann, C.; Feld, L.; Karpinski, W.; Kiesel, K. M.; Klein, K.; Lipinski, M.; Ostapchuk, A.; Pierschel, G.; Preuten, M.; Rauch, M.; Schael, S.; Schomakers, C.; Schulz, J.; Schwering, G.; Wlochal, M.; Zhukov, V.; Pistone, C.; Fluegge, G.; Kuensken, A.; Pooth, O.; Stahl, A.; Aldaya, M.; Asawatangtrakuldee, C.; Beernaert, K.; Bertsche, D.; Contreras-Campana, C.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Gallo, E.; Garay Garcia, J.; Hansen, K.; Haranko, M.; Harb, A.; Hauk, J.; Keaveney, J.; Kalogeropoulos, A.; Kleinwort, C.; Lohmann, W.; Mankel, R.; Maser, H.; Mittag, G.; Muhl, C.; Mussgiller, A.; Pitzl, D.; Reichelt, O.; Savitskyi, M.; Schuetze, P.; Walsh, R.; Zuber, A.; Biskop, H.; Buhmann, P.; Centis-Vignali, M.; Garutti, E.; Haller, J.; Hoffmann, M.; Lapsien, T.; Matysek, M.; Perieanu, A.; Scharf, Ch.; Schleper, P.; Schmidt, A.; Schwandt, J.; Sonneveld, J.; Steinbrück, G.; Vormwald, B.; Wellhausen, J.; Abbas, M.; Amstutz, C.; Barvich, T.; Barth, Ch.; Boegelspacher, F.; De Boer, W.; Butz, E.; Caselle, M.; Colombo, F.; Dierlamm, A.; Freund, B.; Hartmann, F.; Heindl, S.; Husemann, U.; Kornmayer, A.; Kudella, S.; Muller, Th.; Simonis, H. J.; Steck, P.; Weber, M.; Weiler, Th.; Anagnostou, G.; Asenov, P.; Assiouras, P.; Daskalakis, G.; Kyriakis, A.; Loukas, D.; Paspalaki, L.; Siklér, F.; Veszprémi, V.; Bhardwaj, A.; Dalal, R.; Jain, G.; Ranjan, K.; Bakhshiansohl, H.; Behnamian, H.; Khakzad, M.; Naseri, M.; Cariola, P.; Creanza, D.; De Palma, M.; De Robertis, G.; Fiore, L.; Franco, M.; Loddo, F.; Silvestris, L.; Maggi, G.; Martiradonna, S.; My, S.; Selvaggi, G.; Albergo, S.; Cappello, G.; Chiorboli, M.; Costa, S.; Di Mattia, A.; Giordano, F.; Potenza, R.; Saizu, M. A.; Tricomi, A.; Tuve, C.; Barbagli, G.; Brianzi, M.; Ciaranfi, R.; Ciulli, V.; Civinini, C.; D'Alessandro, R.; Focardi, E.; Latino, G.; Lenzi, P.; Meschini, M.; Paoletti, S.; Russo, L.; Scarlini, E.; Sguazzoni, G.; Strom, D.; Viliani, L.; Ferro, F.; Lo Vetere, M.; Robutti, E.; Dinardo, M. E.; Fiorendi, S.; Gennai, S.; Malvezzi, S.; Manzoni, R. A.; Menasce, D.; Moroni, L.; Pedrini, D.; Azzi, P.; Bacchetta, N.; Bisello, D.; Dall'Osso, M.; Pozzobon, N.; Tosi, M.; De Canio, F.; Gaioni, L.; Manghisoni, M.; Nodari, B.; Riceputi, E.; Re, V.; Traversi, G.; Comotti, D.; Ratti, L.; Alunni Solestizi, L.; Biasini, M.; Bilei, G. M.; Cecchi, C.; Checcucci, B.; Ciangottini, D.; Fanò, L.; Gentsos, C.; Ionica, M.; Leonardi, R.; Manoni, E.; Mantovani, G.; Marconi, S.; Mariani, V.; Menichelli, M.; Modak, A.; Morozzi, A.; Moscatelli, F.; Passeri, D.; Placidi, P.; Postolache, V.; Rossi, A.; Saha, A.; Santocchia, A.; Storchi, L.; Spiga, D.; Androsov, K.; Azzurri, P.; Arezzini, S.; Bagliesi, G.; Basti, A.; Boccali, T.; Borrello, L.; Bosi, F.; Castaldi, R.; Ciampa, A.; Ciocci, M. A.; Dell'Orso, R.; Donato, S.; Fedi, G.; Giassi, A.; Grippo, M. T.; Ligabue, F.; Lomtadze, T.; Magazzu, G.; Martini, L.; Mazzoni, E.; Messineo, A.; Moggi, A.; Morsani, F.; Palla, F.; Palmonari, F.; Raffaelli, F.; Rizzi, A.; Savoy-Navarro, A.; Spagnolo, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. G.; Bellan, R.; Costa, M.; Covarelli, R.; Da Rocha Rolo, M.; Demaria, N.; Rivetti, A.; Dellacasa, G.; Mazza, G.; Migliore, E.; Monteil, E.; Pacher, L.; Ravera, F.; Solano, A.; Fernandez, M.; Gomez, G.; Jaramillo Echeverria, R.; Moya, D.; Gonzalez Sanchez, F. J.; Vila, I.; Virto, A. L.; Abbaneo, D.; Ahmed, I.; Albert, E.; Auzinger, G.; Berruti, G.; Bianchi, G.; Blanchot, G.; Bonnaud, J.; Caratelli, A.; Ceresa, D.; Christiansen, J.; Cichy, K.; Daguin, J.; D'Auria, A.; Detraz, S.; Deyrail, D.; Dondelewski, O.; Faccio, F.; Frank, N.; Gadek, T.; Gill, K.; Honma, A.; Hugo, G.; Jara Casas, L. M.; Kaplon, J.; Kornmayer, A.; Kottelat, L.; Kovacs, M.; Krammer, M.; Lenoir, P.; Mannelli, M.; Marchioro, A.; Marconi, S.; Mersi, S.; Martina, S.; Michelis, S.; Moll, M.; Onnela, A.; Orfanelli, S.; Pavis, S.; Peisert, A.; Pernot, J.-F.; Petagna, P.; Petrucciani, G.; Postema, H.; Rose, P.; Tropea, P.; Troska, J.; Tsirou, A.; Vasey, F.; Vichoudis, P.; Verlaat, B.; Zwalinski, L.; Bachmair, F.; Becker, R.; di Calafiori, D.; Casal, B.; Berger, P.; Djambazov, L.; Donega, M.; Grab, C.; Hits, D.; Hoss, J.; Kasieczka, G.; Lustermann, W.; Mangano, B.; Marionneau, M.; Martinez Ruiz del Arbol, P.; Masciovecchio, M.; Meinhard, M.; Perozzi, L.; Roeser, U.; Starodumov, A.; Tavolaro, V.; Wallny, R.; Zhu, D.; Amsler, C.; Bösiger, K.; Caminada, L.; Canelli, F.; Chiochia, V.; de Cosa, A.; Galloni, C.; Hreus, T.; Kilminster, B.; Lange, C.; Maier, R.; Ngadiuba, J.; Pinna, D.; Robmann, P.; Taroni, S.; Yang, Y.; Bertl, W.; Deiters, K.; Erdmann, W.; Horisberger, R.; Kaestli, H.-C.; Kotlinski, D.; Langenegger, U.; Meier, B.; Rohe, T.; Streuli, S.; Cussans, D.; Flacher, H.; Goldstein, J.; Grimes, M.; Jacob, J.; Seif El Nasr-Storey, S.; Cole, J.; Hoad, C.; Hobson, P.; Morton, A.; Reid, I. D.; Auzinger, G.; Bainbridge, R.; Dauncey, P.; Hall, G.; James, T.; Magnan, A.-M.; Pesaresi, M.; Raymond, D. M.; Uchida, K.; Garabedian, A.; Heintz, U.; Narain, M.; Nelson, J.; Sagir, S.; Speer, T.; Swanson, J.; Tersegno, D.; Watson-Daniels, J.; Chertok, M.; Conway, J.; Conway, R.; Flores, C.; Lander, R.; Pellett, D.; Ricci-Tam, F.; Squires, M.; Thomson, J.; Yohay, R.; Burt, K.; Ellison, J.; Hanson, G.; Olmedo, M.; Si, W.; Yates, B. R.; Gerosa, R.; Sharma, V.; Vartak, A.; Yagil, A.; Zevi Della Porta, G.; Dutta, V.; Gouskos, L.; Incandela, J.; Kyre, S.; Mullin, S.; Patterson, A.; Qu, H.; White, D.; Dominguez, A.; Bartek, R.; Cumalat, J. P.; Ford, W. T.; Jensen, F.; Johnson, A.; Krohn, M.; Leontsinis, S.; Mulholland, T.; Stenson, K.; Wagner, S. R.; Apresyan, A.; Bolla, G.; Burkett, K.; Butler, J. N.; Canepa, A.; Cheung, H. W. K.; Chramowicz, J.; Christian, D.; Cooper, W. E.; Deptuch, G.; Derylo, G.; Gingu, C.; Grünendahl, S.; Hasegawa, S.; Hoff, J.; Howell, J.; Hrycyk, M.; Jindariani, S.; Johnson, M.; Kahlid, F.; Lei, C. M.; Lipton, R.; Lopes De Sá, R.; Liu, T.; Los, S.; Matulik, M.; Merkel, P.; Nahn, S.; Prosser, A.; Rivera, R.; Schneider, B.; Sellberg, G.; Shenai, A.; Spiegel, L.; Tran, N.; Uplegger, L.; Voirin, E.; Berry, D. R.; Chen, X.; Ennesser, L.; Evdokimov, A.; Evdokimov, O.; Gerber, C. E.; Hofman, D. J.; Makauda, S.; Mills, C.; Sandoval Gonzalez, I. D.; Alimena, J.; Antonelli, L. J.; Francis, B.; Hart, A.; Hill, C. S.; Parashar, N.; Stupak, J.; Bortoletto, D.; Bubna, M.; Hinton, N.; Jones, M.; Miller, D. H.; Shi, X.; Tan, P.; Baringer, P.; Bean, A.; Khalil, S.; Kropivnitskaya, A.; Majumder, D.; Wilson, G.; Ivanov, A.; Mendis, R.; Mitchell, T.; Skhirtladze, N.; Taylor, R.; Anderson, I.; Fehling, D.; Gritsan, A.; Maksimovic, P.; Martin, C.; Nash, K.; Osherson, M.; Swartz, M.; Xiao, M.; Bloom, K.; Claes, D. R.; Fangmeier, C.; Gonzalez Suarez, R.; Monroy, J.; Siado, J.; Hahn, K.; Sevova, S.; Sung, K.; Trovato, M.; Bartz, E.; Gershtein, Y.; Halkiadakis, E.; Kyriacou, S.; Lath, A.; Nash, K.; Osherson, M.; Schnetzer, S.; Stone, R.; Walker, M.; Malik, S.; Norberg, S.; Ramirez Vargas, J. E.; Alyari, M.; Dolen, J.; Godshalk, A.; Harrington, C.; Iashvili, I.; Kharchilava, A.; Nguyen, D.; Parker, A.; Rappoccio, S.; Roozbahani, B.; Alexander, J.; Chaves, J.; Chu, J.; Dittmer, S.; McDermott, K.; Mirman, N.; Rinkevicius, A.; Ryd, A.; Salvati, E.; Skinnari, L.; Soffi, L.; Tao, Z.; Thom, J.; Tucker, J.; Zientek, M.; Akgün, B.; Ecklund, K. M.; Kilpatrick, M.; Nussbaum, T.; Zabel, J.; Betchart, B.; Covarelli, R.; Demina, R.; Hindrichs, O.; Petrillo, G.; Eusebi, R.; Osipenkov, I.; Perloff, A.; Ulmer, K. A.

    2017-06-01

    The upgrade of the LHC 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 the CMS experiment. Based on these results, the collaboration has chosen to use n-in-p type silicon 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.

  15. Elastic constants determined by nanoindentation for p-type thermoelectric half-Heusler

    Energy Technology Data Exchange (ETDEWEB)

    Gahlawat, S.; Wheeler, L.; White, K. W., E-mail: zren@uh.edu, E-mail: kwwhite@uh.edu [Department of Mechanical Engineering, University of Houston, Houston, Texas 77204 (United States); He, R.; Chen, S.; Ren, Z. F., E-mail: zren@uh.edu, E-mail: kwwhite@uh.edu [Department of Physics and TcSUH, University of Houston, Houston, Texas 77204 (United States)

    2014-08-28

    This paper presents a study of the elastic properties of the p-type thermoelectric half-Heusler material, Hf{sub 0.44}Zr{sub 0.44}Ti{sub 0.12}CoSb{sub 0.8}Sn{sub 0.2}, using nanoindentation. Large grain-sized polycrystalline specimens were fabricated for these measurements, providing sufficient indentation targets within single grains. Electron Backscatter Diffraction methods indexed the target grains for the correlation needed for our elastic analysis of individual single crystals for this cubic thermoelectric material. Elastic properties, including the Zener ratio and the Poisson ratio, obtained from the elasticity tensor are also reported.

  16. Ferromagnetic-resonance induced electromotive forces in Ni81Fe19 | p-type diamond

    Science.gov (United States)

    Fukui, Naoki; Morishita, Hiroki; Kobayashi, Satoshi; Miwa, Shinji; Mizuochi, Norikazu; Suzuki, Yoshishige

    2016-10-01

    We report on direct-current (DC) electromotive forces (emfs) in a nickel-iron alloy (Ni81 Fe19) | p-type diamond under the ferromagnetic resonance of the Ni81Fe19 layer at room temperature. The observed DC emfs take its maximum around the ferromagnetic resonant frequency of the Ni81Fe19, and their signs are reversed by reversing the direction of an externally-applied magnetic field; it shows that the observed DC emfs are spin-related emfs.

  17. Single-structure heater and temperature sensor using a p-type polycrystalline diamond resistor

    Energy Technology Data Exchange (ETDEWEB)

    Yang, G.S.; Aslam, D.M. [Michigan State Univ., East Lansing, MI (United States). Dept. of Electrical Engineering

    1996-05-01

    Heat generation and temperature sensing are required for heating applications and for liquid level sensors, mass flow meters, and vacuum and pressure gauges which are based on variations of heat dissipation. Heat generation and temperature sensing are reported in a single p-type diamond resistor fabricated on an oxidized Si substrate using diamond film technology compatible with integrated circuit (IC) processing. Power densities in excess of 600 W/in.{sup 2} are observed for the heaters. The temperature response of the sensor is characterized in the temperature range of 300--725 K. Such a diamond heater/sensor device is reported for the first time.

  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 intracellular...... 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. Ultra High p-doping Material Research for GaN Based Light Emitters

    Energy Technology Data Exchange (ETDEWEB)

    Vladimir Dmitriev

    2007-06-30

    The main goal of the Project is to investigate doping mechanisms in p-type GaN and AlGaN and controllably fabricate ultra high doped p-GaN materials and epitaxial structures. Highly doped p-type GaN-based materials with low electrical resistivity and abrupt doping profiles are of great importance for efficient light emitters for solid state lighting (SSL) applications. Cost-effective hydride vapor phase epitaxial (HVPE) technology was proposed to investigate and develop p-GaN materials for SSL. High p-type doping is required to improve (i) carrier injection efficiency in light emitting p-n junctions that will result in increasing of light emitting efficiency, (ii) current spreading in light emitting structures that will improve external quantum efficiency, and (iii) parameters of Ohmic contacts to reduce operating voltage and tolerate higher forward currents needed for the high output power operation of light emitters. Highly doped p-type GaN layers and AlGaN/GaN heterostructures with low electrical resistivity will lead to novel device and contact metallization designs for high-power high efficiency GaN-based light emitters. Overall, highly doped p-GaN is a key element to develop light emitting devices for the DOE SSL program. The project was focused on material research for highly doped p-type GaN materials and device structures for applications in high performance light emitters for general illumination P-GaN and p-AlGaN layers and multi-layer structures were grown by HVPE and investigated in terms of surface morphology and structure, doping concentrations and profiles, optical, electrical, and structural properties. Tasks of the project were successfully accomplished. Highly doped GaN materials with p-type conductivity were fabricated. As-grown GaN layers had concentration N{sub a}-N{sub d} as high as 3 x 10{sup 19} cm{sup -3}. Mechanisms of doping were investigated and results of material studies were reported at several International conferences providing

  20. Novel transparent conductor with enhanced conductivity: hybrid of silver nanowires and dual-doped graphene

    Science.gov (United States)

    Sohn, Hiesang; Woo, Yun Sung; Shin, Weonho; Yun, Dong-Jin; Lee, Taek; Kim, Felix Sunjoo; Hwang, Jinyoung

    2017-10-01

    We present hybrid transparent conducting films based on silver nanowires (Ag NWs) and doped graphene through novel dual co-doping method by applying various dopants (HNO3 or Au for p-doping and N2H4 for n-doping) on top and bottom sides of graphene. We systematically investigated the effect of dual-doping on their surface as well as electrical and optical properties of graphene and Ag NW/graphene hybrid films through the combination study with various dopant types (p/p, p/n, n/p, and n/n). We found that the p/p-type dual-doped (p-type dopant: HNO3) graphene and its hybrid formation with Ag NWs appeared to be the most effective in enhancing the electrical properties of conductor (doped graphene with ΔR/R0 = 84% and Ag NW/doped graphene hybrid with ΔR/R0 = 62%), demonstrating doped monolayer graphene with high optical transmittance (TT = 97.4%), and sheet resistance (Rs = 188 Ω/sq.). We also note that dual-doping improved such electrical properties without any significant debilitation of optical transparency of conductors (doped graphene with ΔTT = 0.1% and Ag NW/doped graphene hybrid with ΔTT = 0.4%). In addition, the enhanced conductivity of p-type dual-doped graphene allows a hybrid system to form co-percolating network in which Ag NWs can form a secondary conductive path at grain boundaries of polycrystalline graphene.

  1. A P-type ATPase importer that discriminates between essential and toxic transition metals.

    Science.gov (United States)

    Lewinson, Oded; Lee, Allen T; Rees, Douglas C

    2009-03-24

    Transition metals, although being essential cofactors in many physiological processes, are toxic at elevated concentrations. Among the membrane-embedded transport proteins that maintain appropriate intracellular levels of transition metals are ATP-driven pumps belonging to the P-type ATPase superfamily. These metal transporters may be differentiated according to their substrate specificities, where the majority of pumps can extrude either silver and copper or zinc, cadmium, and lead. In the present report, we have established the substrate specificities of nine previously uncharacterized prokaryotic transition-metal P-type ATPases. We find that all of the newly identified exporters indeed fall into one of the two above-mentioned categories. In addition to these exporters, one importer, Pseudomonas aeruginosa Q9I147, was also identified. This protein, designated HmtA (heavy metal transporter A), exhibited a different substrate recognition profile from the exporters. In vivo metal susceptibility assays, intracellular metal measurements, and transport experiments all suggest that HmtA mediates the uptake of copper and zinc but not of silver, mercury, or cadmium. The substrate selectivity of this importer ensures the high-affinity uptake of essential metals, while avoiding intracellular contamination by their toxic counterparts.

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

    KAUST Repository

    Jiang, Jie

    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.

  3. EEG/MEG forward simulation through h- and p-type finite elements

    Energy Technology Data Exchange (ETDEWEB)

    Pursiainen, S [Institute of Mathematics, Box 1100, FI-02015 Helsinki University of Technology (Finland)], E-mail: sampsa.pursiainen@tkk.fi

    2008-07-15

    Electro/Magnetoencephalography (EEG/MEG) is a non-invasive imaging modality, in which a primary current density generated by the neural activity in the brain is to be reconstructed from external electric potential/magnetic field measurements. This work focuses on effective and accurate simulation of the EEG/MEG forward model through the h- and p-versions of the finite element method (h- and p-FEM). The goal is to compare the effectiveness of these two versions in forward simulation. Both h- and p-type forward simulations are described and implemented, and the technical solutions found are discussed. These include, for example, suitable ways to generate a finite element mesh for a real head geometry through the use of different element types. Performances of the two implemented forward simulation types are compared by measuring directly the forward modeling error, as well as by computing reconstructions through a regularized FOCUSS (FOCal Underdetermined System Solver) algorithm. The results obtained suggest that the p-type performs better in terms of the forward modeling error. However, both types perform well in regularized FOCUSS reconstruction.

  4. Carrier induced local moment magnetization in p-type Sn1-xMnxTe

    Science.gov (United States)

    Behera, Sashi S.; Tripathi, Pratibha; Nayak, Sanjeev K.; Tripathi, Gouri S.

    2017-08-01

    We derive a theory of carrier induced local moment magnetization of p-type Sn1-xMnxTe based on the Hubbard model, k → · π → electronic structure method (k → is the electronic wave vector and π → is the relativistic momentum operator) and the statistical paramagnetic approach for the localized moments. The Hubbard model is used to derive an internal exchange magnetic field. The difference in exchange self-energy is expressed in terms of an internal exchange field that is proportional to the parameter U, the onsite Coulomb repulsion, and the spin-density of carriers. In the present theory, the k → · π → + U model is integrated with the statistical paramagnetic theory for localized spins, which is then solved in a self-consistent manner by adding the exchange field to the applied field. The technique is applied to study the magnetic properties of p-type Sn1-xMnxTe, an important material for spintronics devices. The local moment magnetization calculated using the total magnetic field self-consistently agrees with the experimental observations. Magnetization and the exchange field studied as functions of the applied field, temperature and carrier concentration yield results on expected lines. Ours is a mechanism that is different from the RKKY interaction, normally invoked for carrier induced ferromagnetism and is thus a novelty.

  5. Anabaena sp. DyP-type peroxidase is a tetramer consisting of two asymmetric dimers.

    Science.gov (United States)

    Yoshida, Toru; Ogola, Henry Joseph Oduor; Amano, Yoshimi; Hisabori, Toru; Ashida, Hiroyuki; Sawa, Yoshihiro; Tsuge, Hideaki; Sugano, Yasushi

    2016-01-01

    DyP-type peroxidases are a newly discovered family of heme peroxidases distributed from prokaryotes to eukaryotes. Recently, using a structure-based sequence alignment, we proposed the new classes, P, I and V, as substitutes for classes A, B, C, and D [Arch Biochem Biophys 2015;574:49-55]. Although many class V enzymes from eukaryotes have been characterized, only two from prokaryotes have been reported. Here, we show the crystal structure of one of these two enzymes, Anabaena sp. DyP-type peroxidase (AnaPX). AnaPX is tetramer formed from Cys224-Cys224 disulfide-linked dimers. The tetramer of wild-type AnaPX was stable at all salt concentrations tested. In contrast, the C224A mutant showed salt concentration-dependent oligomeric states: in 600 mM NaCl, it maintained a tetrameric structure, whereas in the absence of salt, it dissociated into monomers, leading to a reduction in thermostability. Although the tetramer exhibits non-crystallographic, 2-fold symmetry in the asymmetric unit, two subunits forming the Cys224-Cys224 disulfide-linked dimer are related by 165° rotation. This asymmetry creates an opening to cavities facing the inside of the tetramer, providing a pathway for hydrogen peroxide access. Finally, a phylogenetic analysis using structure-based sequence alignments showed that class V enzymes from prokaryotes, including AnaPX, are phylogenetically closely related to class V enzymes from eukaryotes.

  6. Lateral photovoltaic effect in p-type silicon induced by surface states

    Science.gov (United States)

    Huang, Xu; Mei, Chunlian; Gan, Zhikai; Zhou, Peiqi; Wang, Hui

    2017-03-01

    A colossal lateral photovoltaic effect (LPE) was observed at the surface of p-type silicon, which differs from the conventional thought that a large LPE is only observed in Schottky junctions and PN junctions consisting of several layers with different conductivities. It shows a high sensitivity of 499.24 mV/mm and an ultra-broadband spectral responsivity (from 405 nm to 980 nm) at room temperature, which makes it an attractive candidate for near-infrared detection. We propose that this phenomenon can be understood by considering the surface band bending near the surface of p-Si induced by charged surface states. The energy band diagrams of the samples are shown based on X-ray photoelectron spectroscopy suggesting the correlation between the LPE and surface band bending. The conjectures are validated by changing the surface states of p-type silicon using Ni nano-films. These findings reveal a generation mechanism of the LPE and may lead to p-Si based, broadband-responsivity, low-cost, and high-precision optical and optoelectronic applications.

  7. A novel ultra steep dynamically reconfigurable electrostatically doped silicon nanowire Schottky Barrier FET

    Science.gov (United States)

    Singh, Sangeeta; Sinha, Ruchir; Kondekar, P. N.

    2016-05-01

    In this paper, an ultra steep, symmetric and dynamically configurable, electrostatically doped silicon nanowire Schottky FET (E-SiNW-SB-FET) based on dopant-free technology is investigated. It achieves the ultra steep sub-threshold slope (SS) due to the cumulative effect of weak impact-ionization induced positive feedback and electrostatic modulation of Schottky barrier heights at both source and drain terminals. It consists of axial nanowire heterostructure (silicide-intrinsic silicon-silicide) with three independent all-around gates, two gates are polarity control gates for dynamically reconfiguring the device polarity by modulating the effective Schottky barrier heights and a control gate switches the device ON and OFF. The most interesting features of the proposed structure are simplified fabrication process as the state-of-the-art for ion implantation and high thermal budget no more required for annealing. It is highly immune to process variations, doping control issues and random dopant fluctuations (RDF) and there are no mobility degradation issues related to high doping. A calibrated 3-D TCAD simulation results exhibit the SS of 2 mV/dec for n-type E-SiNW-SB-FET and 9 mV/dec for p-type E-SiNW-SB-FET for about five decades of current. Further, it resolves all the reliability related issues of IMOS as hot electron effects are no more limiting our device performance. It offers significant drive current of the order of 10-5-10-4 A and magnificently high ION/IOFF ratio of ∼108 along with the inherent advantages of symmetric device structure for its circuit realization.

  8. New photovoltaic devices based on the sensitization of p-type semiconductors: challenges and opportunities.

    Science.gov (United States)

    Odobel, Fabrice; Le Pleux, Loïc; Pellegrin, Yann; Blart, Errol

    2010-08-17

    Because solar energy is the most abundant renewable energy resource, the clear connection between human activity and global warming has strengthened the interest in photovoltaic science. Dye-sensitized solar cells (DSSCs) provide a promising low-cost technology for harnessing this energy source. Until recently, much of the research surrounding DSSCs had been focused on the sensitization of n-type semiconductors, such as titanium dioxide (Gratzel cells). In an n-type dye-sensitized solar cell (n-DSSC), an electron is injected into the conduction band of an n-type semiconductor (n-SC) from the excited state of the sensitizer. Comparatively few studies have examined the sensitization of wide bandgap p-type semiconductors. In a p-type DSSC (p-DSSC), the photoexcited sensitizer is reductively quenched by hole injection into the valence band of a p-type semiconductor (p-SC). The study of p-DSSCs is important both to understand the factors that control the rate of hole photoinjection and to aid the rational design of efficient p-DSSCs. In theory, p-DSSCs should be able to work as efficiently as n-DSSCs. In addition, this research provides a method for preparing tandem DSSCs consisting of a TiO(2)-photosensitized anode and a photosensitized p-type SC as a cathode. Tandem DSSCs are particularly important because they represent low-cost photovoltaic devices whose photoconversion efficiencies could exceed 15%. This Account describes recent research results on p-DSSCs. Because these photoelectrochemical devices are the mirror images of conventional n-DSSCs, they share some structural similarities, but they use different materials and have different charge transfer kinetics. In this technology, nickel oxide is the predominant p-SC material used, but much higher photoconversion efficiencies could be achieved with new p-SCs materials with deeper valence band potential. Currently, iodide/triiodide is the main redox mediator of electron transport within these devices, but we expect

  9. 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.

  10. Synthesis of S-doped graphene by liquid precursor.

    Science.gov (United States)

    Gao, Hui; Liu, Zheng; Song, Li; Guo, Wenhua; Gao, Wei; Ci, Lijie; Rao, Amrita; Quan, Weijin; Vajtai, Robert; Ajayan, Pulickel M

    2012-07-11

    Doping is a common and effective approach to tailor semiconductor properties. Here, we demonstrate the growth of large-area sulfur (S)-doped graphene sheets on copper substrate via the chemical vapor deposition technique by using liquid organics (hexane in the presence of S) as the precursor. We found that S could be doped into graphene's lattice and mainly formed linear nanodomains, which was proved by elemental analysis, high resolution transmission microscopy and Raman spectra. Measurements on S-doped graphene field-effect transistors (G-FETs) revealed that S-doped graphene exhibited lower conductivity and distinctive p-type semiconductor properties compared with those of pristine graphene. Our approach has produced a new member in the family of graphene based materials and is promising for producing graphene based devices for multiple applications.

  11. Calcium decorated and doped phosphorene for gas adsorption

    Science.gov (United States)

    Lalitha, Murugan; Nataraj, Yuvarani; Lakshmipathi, Senthilkumar

    2016-07-01

    In this paper, we present the results from first-principles study based on the electronic structure and adsorption characteristics of CH4, CO2, H2 and NH3 adsorbed on Ca decorated/doped phosphorene. Our study finds that phosphorene exhibits n-type behaviour on decorating calcium, and p-type on doping calcium. Gas molecules are physisorbed on both pristine and calcium-mediated phosphorene, visible through their lower binding energy and charge transfer values. Ca decorated phosphorene is suitable for hydrogen storage due to its higher binding energy for H2. Ca doped structures shows increased binding affinity towards CH4 and NH3 in zigzag1 direction and armchair directions respectively. The extracts of our study implies that Ca doped phosphorene possess increased binding affinity towards gas molecules, and the results are highly helpful for gas adsorption and to design gas sensors based on calcium doped or decorated phosphorene.

  12. Carbon doping of GaAs NWs

    Science.gov (United States)

    Salehzadeh Einabad, Omid

    Nanowires (NWs) have been proposed and demonstrated as the building blocks for nanoscale electronic and photonic devices such as NW field effect transistors and NW solar cells which rely on doping and trap-free carrier transport. Controlled doping of NWs and a high degree of structure and morphology control are required for device applications. However, doping of III-V nanowires such as GaAs nanowires has not been reported extensively in the literature. Carbon is a well known p-type dopant in planar GaAs due to its low diffusivity and high solubility in bulk GaAs; however its use as an intentional dopant in NW growth has not yet been investigated. In this work we studied the carbon doping of GaAs nanowires using CBr4 as the dopant source. Gold nanoparticles (NP) at the tip ofthe NWs have been used to drive the NW growth. We show that carbon doping suppresses the migration ofthe gold NPs from the tip of the NWs. In addition, we show that the carbon doping of GaAs NWs is accompanied by an increase of the axial growth rate and decrease of the lateral growth rate ofthe NWs. Carbon-doped GaAs NWs, unlike the undoped ones which are highly tapered, are rod-like. The origin of the observed morphological changes is attributed to the carbon adsorbates on the sidewalls ofthe nanowires which suppress the lateral growth of the nanowires and increase the diffusion length of the gallium adatoms on the sidewalls. Stacking fault formation consisting of alternating regIOns of zincblende and wurtzite structures has been commonly observed in NWs grown along the (111) direction. In this work, based on transmission electron microscopy (TEM) analysis, we show that carbon doping ofGaAs NWs eliminates the stacking fault formation. Raman spectroscopy was used to investigate the effects of carbon doping on the vibrational properties of the carbon-doped GaAs nanowires. Carbon doping shows a strong impact on the intrinsic longitudinal and transverse optical (La and TO) modes of the Ga

  13. Modulation of electromagnetic and absorption properties in 18-26.5 GHz frequency range of strontium hexaferrites with doping of cobalt-zirconium

    Energy Technology Data Exchange (ETDEWEB)

    Pubby, Kunal; Narang, Sukhleen Bindra [Guru Nanak Dev University, Department of Electronics Technology, Amritsar (India); Kaur, Prabhjyot; Chawla, S.K. [Guru Nanak Dev University, Department of Chemistry, Centre for Advanced Studies-I, Amritsar (India)

    2017-05-15

    Hexaferrite nano-particles of stoichiometric composition Sr(CoZr){sub x}Fe{sub 12-2x}O{sub 19}, with x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 were prepared using sol-gel auto-combustion route owing to its advantages such as low sintering temperature requirement, homogeneity and uniformity of grains. Tartaric acid as a fuel was utilized to complete the chemical reaction. The goal of this study is to analyse the effect of co-substitution of cobalt and zirconium on the electromagnetic and absorption properties of pure SrFe{sub 12}O{sub 19} hexaferrite. The properties were measured on the rectangular pellets of thickness 2.5 mm for K-frequency band using Vector Network Analyzer. The doping of Co-Zr has resulted in increase in real as well as imaginary parts of permittivity. The values of real permittivity lie in the range 3.6-7.0 for all the composition. The real part of permeability remains in range 0.7-1.6 in the studied frequency band for all the samples and shows slightly increasing trend with frequency. The maximum values of dielectric loss tangent peak (3.04) and magnetic loss tangent peak (2.34), among all the prepared compositions, have been observed for composition x = 0.2. Compositions with x = 0.6 and x = 0.0 also have high dielectric and magnetic loss peaks. Dielectric loss peaks are attributed to dielectric resonance and magnetic loss peaks are attributed to natural resonance. Experimentally determined reflection loss results show that all six compositions of prepared series have high values of absorption to propose them as single-layer absorbers in 18-26.5 GHz frequency range. The composition with x = 0.2 has maximum absorption capacity with reflection loss peak of -37.2 dB at 24.3 GHz frequency. The undoped composition also has high absorption peak (-25.46 dB), but -10 dB absorption bandwidth is minimum (2.2 GHz) out of the present series. Maximum absorption bandwidth is obtained for x = 1.0 (4.1 GHz). Other doped compositions also have high absorption bandwidth

  14. Heterovalent cation substitutional doping for quantum dot homojunction solar cells

    Science.gov (United States)

    Stavrinadis, Alexandros; Rath, Arup K.; de Arquer, F. Pelayo García; Diedenhofen, Silke L.; Magén, César; Martinez, Luis; So, David; Konstantatos, Gerasimos

    2013-12-01

    Colloidal quantum dots have emerged as a material platform for low-cost high-performance optoelectronics. At the heart of optoelectronic devices lies the formation of a junction, which requires the intimate contact of n-type and p-type semiconductors. Doping in bulk semiconductors has been largely deployed for many decades, yet electronically active doping in quantum dots has remained a challenge and the demonstration of robust functional optoelectronic devices had thus far been elusive. Here we report an optoelectronic device, a quantum dot homojunction solar cell, based on heterovalent cation substitution. We used PbS quantum dots as a reference material, which is a p-type semiconductor, and we employed Bi-doping to transform it into an n-type semiconductor. We then combined the two layers into a homojunction device operating as a solar cell robustly under ambient air conditions with power conversion efficiency of 2.7%.

  15. NbFeSb based p-type half-Heusler for power generation applications

    Science.gov (United States)

    Joshi, Giri; He, Ran; Engber, Michael; Samsonidze, Georgy; Pantha, Tej; Dahal, Ekraj; Dahal, Keshab; Yang, Jian; Lan, Yucheng; Kozinsky, Boris; Ren, Zhifeng

    2015-03-01

    We report a peak dimensionless figure-of-merit (ZT) of ~1 at 700 oC in nanostructured p-type Nb0.6Ti0.4FeSb0.95Sn0.05composition. Even though the power factor of the Nb0.6Ti0.4FeSb0.95Sn0.05 composition is improved by 25% in comparison to the previously reported p-type Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2, the ZT value is not increased due to a higher thermal conductivity. However, the higher power factor of the Nb0.6Ti0.4FeSb0.95Sn0.05 composition led to a 15% increase in power output of a thermoelectric device in comparison to a device made from the previous best material Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2. The n-type material used to make the unicouple device is the best reported nanostructured Hf0.25Zr0.75NiSn0.99Sb0.01 composition with the lowest hafnium (Hf) content. Both the p- and n-type nanostructured samples are prepared by ball milling the arc melted ingot and hot pressing the finely ground powders. Moreover, the raw material cost of the Nb0.6Ti0.4FeSb0.95Sn0.05 composition is more than six times lower compared to the cost of the previous best p-type Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2. This cost reduction is crucial for these materials to be used in large-scale quantities for vehicle and industrial waste heat recovery applications. DOE:DE-EE0004840.

  16. [Doping and urologic tumors].

    Science.gov (United States)

    Pinto, F; Sacco, E; Volpe, A; Gardi, M; Totaro, A; Calarco, A; Racioppi, M; Gulino, G; D'Addessi, A; Bassi, P F

    2010-01-01

    Several substances such as growth hormone (GH), erythropoietin (Epo), and anabolic steroids (AS) are improperly utilized to increase the performance of athletes. Evaluating the potential cancer risk associated with doping agents is difficult since these drugs are often used at very high doses and in combination with other licit or illicit drugs. The GH, via its mediator, the insulin-like growth factor 1 (IGF-1), is involved in the development and progression of cancer. Animal studies suggested that high levels of GH/IGF-1 increase progression of androgen-independent prostate cancer. Clinical data regarding prostate cancer are mostly based on epidemiological studies or indirect data such as IGF-1 high levels in patients with prostate cancer. Even if experimental studies showed a correlation between Epo and cancer, no clinical data are currently available on cancer development related to Epo as a doping agent. Androgens are involved in prostate carcinogenesis modulating genes that regulate cell proliferation, apoptosis and angiogenesis. Most information on AS is anecdotal (case reports on prostate, kidney and testicular cancers). Prospective epidemiologic studies failed to support the hypothesis that circulating androgens are positively associated with prostate cancer risk. Currently, clinical and epidemiological studies supporting association between doping and urological neoplasias are not available. Nowadays, exposure to doping agents starts more prematurely with a consequent longer exposition period; drugs are often used at very high doses and in combination with other licit or illicit drugs. Due to all these elements it is impossible to predict all the side effects, including cancer; more detailed studies are therefore necessary.

  17. Synthesis of Na-doped ZnO hollow spheres with improved photocatalytic activity for hydrogen production.

    Science.gov (United States)

    Wu, Zhiwei; Li, Yaguang; Gao, Linjie; Wang, Shufang; Fu, Guangsheng

    2016-07-05

    The fabrication of p-type doped ZnO nanostructures is key in opening up substantial opportunities for the application of ZnO nanostructures. Owing to their stable p-type property, Na ions are the best candidates for ZnO p-type doping. However, Na-doped ZnO nanostructures had never been prepared until now. For the first time, we successfully synthesized Na-doped ZnO ultrathin hollow spheres using an ion adsorption and templating method. The obtained hollow spheres have ultrathin shells, uniform Na elemental distribution and a controllable concentration of doped Na. The energy position of the Fermi level decreased with continuously increasing Na doping concentration, revealing the p-type conductivity of Na-doped ZnO. We demonstrate that the photocatalytic hydrogen generation efficiency (with methanol) using ZnO ultrathin hollow spheres can be enhanced by more than 50 times after Na-doping and that the quantum efficiency can be as high as 13.5%.

  18. First-principles study on electronic and magnetic properties of N mono-doped and (N, Co) co-doped ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Abbad, A., E-mail: am.ben@voila.fr [Laboratory of Material Valorisation, Faculty of Sciences and Technology, BP 227, Abdelhamid Ibn Badis University, Mostaganem 27000 (Algeria); Bentounes, H.A. [Signals and Systems Laboratory (LSS), Faculty of Sciences and Technology, BP 227, Abdelhamid Ibn Badis University, Mostaganem 27000 (Algeria); Benstaali, W. [Laboratory of Material Valorisation, Faculty of Sciences and Technology, BP 227, Abdelhamid Ibn Badis University, Mostaganem 27000 (Algeria); Belaidi, A. [Automatic and Systems Analysis Laboratory (LAAS), ENSET, Oran 31000 (Algeria)

    2013-01-15

    Using first principles calculations based on the density functional theory and local spin density approximation, we predict magnetic and electronic properties of N mono-doped and (N-Co) co-doped ZnO for different dopants concentration. The results show that ZnO doped with N concentration of 12.5% is p-type, semi-metallic and ferromagnetic due to the strong hybridization effect between N 2p and O 2p states, with a total magnetic moment of 1 {mu}{sub B} mainly arises from N 2p orbitals. Nevertheless we find a deep and narrow acceptor level, resulting in large acceptor ionization energy of ZnO (N). With increasing N concentration to 25% we find that the impurity energy level is shallow and shifts downward to the direction of low energy, consequentially, the acceptor binding energy is reduced. (N-Co) co-doped ZnO with a concentration of 12.5% for the two dopants is p-type and half-metallic with an important magnetic moment of 3.98 {mu}{sub B}, due to Co 3d and N 2p states. - Highlights: Black-Right-Pointing-Pointer The electronic and magnetic properties of N mono-doped and (N-Co) co-doped ZnO have been investigated. Black-Right-Pointing-Pointer ZnO doped with 12.5% of Nitrogen is p-type and semi-metallic. Black-Right-Pointing-Pointer N-doping can enhance electronic conductivity of N-doped ZnO. Black-Right-Pointing-Pointer We find narrow N-impurity band for N-doped ZnO. Black-Right-Pointing-Pointer The co-doping of Co donors with N-acceptors causes an important change from semi-metallic material to half-metallic one.

  19. The psychology of doping.

    Science.gov (United States)

    Elbe, Anne-Marie; Barkoukis, Vassilis

    2017-08-01

    Doping is increasingly becoming a problem in both elite and recreational sports. It is therefore important to understand the psychological factors which can explain doping behavior in order to prevent it. The present paper briefly presents evidence on the prevalence of doping use in competitive sports and the measurement approaches to assess doping behavior and doping-related variables. Furthermore, the integrative theoretical approaches used to describe the psychological processes underlying doping use are discussed. Finally, the paper provides suggestions for appropriate measurement of doping behavior and doping-related variables, key preventive efforts against doping as well as avenues for future research. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2017-04-01

    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 cm2 V-1 s-1, which is much higher than that of MoS2 monolayer. These findings make SnO monolayer becomes a promising 2D material for applications in nanoelectronic devices.

  1. How thermoelectric properties of p-type Tl-filled skutterudites are improved

    Directory of Open Access Journals (Sweden)

    Donghun Kim

    2013-09-01

    Full Text Available The high-temperature thermoelectric properties of p-type Tl-filled skutterudites TlxFe1Co3Sb12 (x = 0, 0.2, 0.4, 0.6, and 0.8 were examined. While samples with x ≤ 0.4 were single-phase Tl-filled skutterudite, samples with x = 0.6 and 0.8 were composed of two phases: TlxFe1Co3Sb12 (x ≈ 0.4 as the matrix phase and a Tl-Fe-Sb ternary alloy. The thermal conductivity (κ was reduced effectively by Tl addition, but the secondary phase increased κ slightly. The maximum value of the dimensionless figure of merit ZT (=S2T/ρ/κ, where T is the absolute temperature was 0.36 at 723 K for Tl0.2Fe1Co3Sb12.

  2. P-type calcium channels are blocked by the alkaloid daurisoline.

    Science.gov (United States)

    Lu, Y M; Fröstl, W; Dreessen, J; Knöpfel, T

    1994-07-21

    IN looking for a structurally defined non-peptide P-channel blocker we have tested the alkaloid daurisoline which has been isolated from traditional Chinese medicinal herb (Menispermum dauricum) used for the treatment of epilepsy, hypertension and asthma. We have found that daurisoline is an inhibitor of omega-Aga-IVA sensitive barium currents in cerebellar Purkinje cells and of excitatory postsynaptic potentials evoked in Purkinje cells by stimulating parallel fibres in acutely prepared cerebellar slices. Daurisoline did not significantly affect omega-Aga-IVA-insensitive barium currents recorded from granule cells freshly isolated from rat cerebellum. Daurisoline passes the blood-brain barrier and will, therefore, facilitate the functional characterization of brain calcium channels as well as the exploration of P-type calcium channels as possible drug targets.

  3. 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.

  4. Improved thermoelectric efficiency in p-type ZnSb through Zn deficiency

    Science.gov (United States)

    Guo, Qilong; Luo, Sijun

    2015-12-01

    We herein report a feasible approach to improve the thermoelectric performance of p-type ZnSb compound by Zn content regulation. It is found that Zn vacancies formed by Zn deficiency not only efficiently enhance the electrical conductivity due to the improved hole concentration but also markedly lower the lattice thermal conductivity on account of the reinforced point defect scattering of phonons. The ZnSb compound with a nominal 3 mol.% Zn deficiency shows a maximum thermoelectric figure of merit ZT of 0.8 at 700 K which is a 60% improvement over the pristine sample. The strategies of further enhancing the performance of ZnSb-based material have been discussed.

  5. Origin of resistivity anomaly in p-type leads chalcogenide multiphase compounds

    Energy Technology Data Exchange (ETDEWEB)

    Aminorroaya Yamini, Sima, E-mail: sima@uow.edu.au, E-mail: jsnyder@caltech.edu; Dou, Shi Xue [Australian Institute for Innovative Materials (AIIM), Innovation Campus, University of Wollongong, NSW 2500 (Australia); Mitchell, David R. G. [Electron Microscopy Centre (EMC), Australian Institute for Innovative Materials (AIIM), Innovation Campus, University of Wollongong, NSW 2500 (Australia); Wang, Heng [Materials Science, California Institute of Technology, Pasadena, CA 91125 (United States); Gibbs, Zachary M. [Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125 (United States); Pei, Yanzhong [School of Materials Science and Engineering, Tongji University, 4800 Caoan Road, Shanghai 201804 (China); Snyder, G. Jeffrey, E-mail: sima@uow.edu.au, E-mail: jsnyder@caltech.edu [Electron Microscopy Centre (EMC), Australian Institute for Innovative Materials (AIIM), Innovation Campus, University of Wollongong, NSW 2500 (Australia); ITMO University, Saint Petersburg (Russian Federation)

    2015-05-15

    The electrical resistivity curves for binary phase compounds of p-type lead chalcogenide (PbTe){sub (0.9−x)}(PbSe){sub 0.1}(PbS){sub x,} (x = 0.15, 0.2, 0.25), which contain PbS-rich secondary phases, show different behaviour on heating and cooling between 500-700 K. This is contrast to single phase compounds which exhibit similar behaviour on heating and cooling. We correlate these anomalies in the electrical resistivities of multiphase compounds to the variation in phase composition at high temperatures. The inhomogeneous distribution of dopants between the matrix and secondary phase is found to be crucial in the electronic transport properties of the multiphase compounds. These results can lead to further advances in designing composite Pb-chalcogenides with high thermoelectric performance.

  6. Photostable p-type dye-sensitized photoelectrochemical cells for water reduction.

    Science.gov (United States)

    Ji, Zhiqiang; He, Mingfu; Huang, Zhongjie; Ozkan, Umit; Wu, Yiying

    2013-08-14

    A photostable p-type NiO photocathode based on a bifunctional cyclometalated ruthenium sensitizer and a cobaloxime catalyst has been created for visible-light-driven water reduction to produce H2. The sensitizer is anchored firmly on the surface of NiO, and the binding is resistant to the hydrolytic cleavage. The bifunctional sensitizer can also immobilize the water reduction catalyst. The resultant photoelectrode exhibits superior stability in aqueous solutions. Stable photocurrents have been observed over a period of hours. This finding is useful for addressing the degradation issue in dye-sensitized photoelectrochemical cells caused by desorption of dyes and catalysts. The high stability of our photocathodes should be important for the practical application of these devices for solar fuel production.

  7. Phonon bottleneck in p-type Ge/Si quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Yakimov, A. I., E-mail: yakimov@isp.nsc.ru [Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Science, 630090 Novosibirsk (Russian Federation); Tomsk State University, 634050 Tomsk (Russian Federation); Kirienko, V. V.; Armbrister, V. A. [Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Science, 630090 Novosibirsk (Russian Federation); Bloshkin, A. A.; Dvurechenskii, A. V. [Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Science, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation)

    2015-11-23

    We study the effect of quantum dot size on the mid-infrared photo- and dark current, photoconductive gain, and hole capture probability in ten-period p-type Ge/Si quantum dot heterostructures. The dot dimensions are varied by changing the Ge coverage and the growth temperature during molecular beam epitaxy of Ge/Si(001) system in the Stranski-Krastanov growth mode. In all samples, we observed the general tendency: with decreasing the size of the dots, the dark current and hole capture probability are reduced, while the photoconductive gain and photoresponse are enhanced. Suppression of the hole capture probability in small-sized quantum dots is attributed to a quenched electron-phonon scattering due to phonon bottleneck.

  8. Improved performance of P-type DSCs with a compact blocking layer coated by different thicknesses

    Science.gov (United States)

    Ho, Phuong; Bao, Le Quoc; Cheruku, Rajesh; Kim, Jae Hong

    2016-09-01

    The introduction of different thicknesses of a compact NiO blocking layer coating with different spin speeds on FTO and followed by a coating of photoactive NiO electrode for p-type dye-sensitized solar cells ( p-DSCs). This study examined the fabrication of a compact NiO blocking layer by decomposing an ethanolic precursor solution of nickel acetate tetrahydrate. The DCBZ dye used as the photosensitizer for the NiO electrode in the p-DSCs device and their performances have been analyzed. The enhancement of photovoltaic performance and resulted from an increase in the power conversion efficiency ( η). The electrochemical impedance spectroscopy (EIS) measurement demonstrated that charge recombination was suppressed when a compact NiO blocking layer was applied. The results showed that the best p-DSC was achieved by employing 3000 rpm spin-coated process for different times of blocking layer.

  9. Empirical model predicting the layer thickness and porosity of p-type mesoporous silicon

    Science.gov (United States)

    Wolter, Sascha J.; Geisler, Dennis; Hensen, Jan; Köntges, Marc; Kajari-Schröder, Sarah; Bahnemann, Detlef W.; Brendel, Rolf

    2017-04-01

    Porous silicon is a promising material for a wide range of applications because of its versatile layer properties and the convenient preparation by electrochemical etching. Nevertheless, the quantitative dependency of the layer thickness and porosity on the etching process parameters is yet unknown. We have developed an empirical model to predict the porosity and layer thickness of p-type mesoporous silicon prepared by electrochemical etching. The impact of the process parameters such as current density, etching time and concentration of hydrogen fluoride is evaluated by ellipsometry. The main influences on the porosity of the porous silicon are the current density, the etching time and their product while the etch rate is dominated by the current density, the concentration of hydrogen fluoride and their product. The developed model predicts the resulting layer properties of a certain porosification process and can, for example be used to enhance the utilization of the employed chemicals.

  10. 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...

  11. Inkjet printed circuits based on ambipolar and p-type carbon nanotube thin-film transistors

    Science.gov (United States)

    Kim, Bongjun; Geier, Michael L.; Hersam, Mark C.; Dodabalapur, Ananth

    2017-02-01

    Ambipolar and p-type single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) are reliably integrated into various complementary-like circuits on the same substrate by inkjet printing. We describe the fabrication and characteristics of inverters, ring oscillators, and NAND gates based on complementary-like circuits fabricated with such TFTs as building blocks. We also show that complementary-like circuits have potential use as chemical sensors in ambient conditions since changes to the TFT characteristics of the p-channel TFTs in the circuit alter the overall operating characteristics of the circuit. The use of circuits rather than individual devices as sensors integrates sensing and signal processing functions, thereby simplifying overall system design.

  12. Bulk and Surface Event Identification in p-type Germanium Detectors

    CERN Document Server

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

    2016-01-01

    The p-type point-contact germanium detectors, due to its sub-keV sensitivities and low internal radioactivity background, are demonstrated to be competitive tools for light dark matter WIMPs searches and may have potential applications in neutrino physics. These detectors exhibit anomalous surface behavior, which has been characterized and dealt with in previous analysis. However, the analysis method rely on spectral shape assumptions and must use external calibration sources. In this report, we purpose an improved method, where in situ data could be used as calibration sources. Data from CDEX-1 and TEXONO experiments will be re-examined and the results are shown to be consistent with both analysis.

  13. Chemical Composition of Nanoporous Layer Formed by Electrochemical Etching of p-Type GaAs

    Science.gov (United States)

    Bioud, Youcef A.; Boucherif, Abderraouf; Belarouci, Ali; Paradis, Etienne; Drouin, Dominique; Arès, Richard

    2016-10-01

    We have performed a detailed characterization study of electrochemically etched p-type GaAs in a hydrofluoric acid-based electrolyte. The samples were investigated and characterized through cathodoluminescence (CL), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). It was found that after electrochemical etching, the porous layer showed a major decrease in the CL intensity and a change in chemical composition and in the crystalline phase. Contrary to previous reports on p-GaAs porosification, which stated that the formed layer is composed of porous GaAs, we report evidence that the porous layer is in fact mainly constituted of porous As2O3. Finally, a qualitative model is proposed to explain the porous As2O3 layer formation on p-GaAs substrate.

  14. Inkjet printed circuits based on ambipolar and p-type carbon nanotube thin-film transistors

    Science.gov (United States)

    Kim, Bongjun; Geier, Michael L.; Hersam, Mark C.; Dodabalapur, Ananth

    2017-01-01

    Ambipolar and p-type single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) are reliably integrated into various complementary-like circuits on the same substrate by inkjet printing. We describe the fabrication and characteristics of inverters, ring oscillators, and NAND gates based on complementary-like circuits fabricated with such TFTs as building blocks. We also show that complementary-like circuits have potential use as chemical sensors in ambient conditions since changes to the TFT characteristics of the p-channel TFTs in the circuit alter the overall operating characteristics of the circuit. The use of circuits rather than individual devices as sensors integrates sensing and signal processing functions, thereby simplifying overall system design. PMID:28145438

  15. Inkjet printed circuits based on ambipolar and p-type carbon nanotube thin-film transistors.

    Science.gov (United States)

    Kim, Bongjun; Geier, Michael L; Hersam, Mark C; Dodabalapur, Ananth

    2017-02-01

    Ambipolar and p-type single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) are reliably integrated into various complementary-like circuits on the same substrate by inkjet printing. We describe the fabrication and characteristics of inverters, ring oscillators, and NAND gates based on complementary-like circuits fabricated with such TFTs as building blocks. We also show that complementary-like circuits have potential use as chemical sensors in ambient conditions since changes to the TFT characteristics of the p-channel TFTs in the circuit alter the overall operating characteristics of the circuit. The use of circuits rather than individual devices as sensors integrates sensing and signal processing functions, thereby simplifying overall system design.

  16. Asymptotics of the trap-dominated Gunn effect in p-type Ge

    Science.gov (United States)

    Bonilla, L. L.; Hernando, P. J.; Herrero, M. A.; Kindelan, M.; Velázquez, J. J. L.

    1997-09-01

    We present an asymptotic analysis of the Gunn effect in a drift-diffusion model - including electric-field-dependent generation-recombination processes - for long samples of strongly compensated p-type Ge at low temperature and under d.c. voltage bias. During each Gunn oscillation, there are different stages corresponding to the generation, motion and annihilation of solitary waves. Each stage may be described by one evolution equation for only one degree of freedom (the current density), except for the generation of each new wave. The wave generation is a faster process that may be described by solving a semiinfinite canonical problem. As a result of our study we have found that (depending on the boundary condition) one or several solitary waves may be shed during each period of the oscillation. Examples of numerical simulations validating our analysis are included.

  17. DLTS of p-type Czochralski Si wafers containing processing-induced macropores

    Science.gov (United States)

    Simoen, E.; Depauw, V.; Gordon, I.; Poortmans, J.

    2012-01-01

    The deep levels present in p-type Czochralski silicon with processing-induced macropores in the depletion region have been studied by the deep-level transient (DLT) spectroscopy technique. It is shown that a broad band is present for a bias pulse close to the interface with the Al Schottky contact, which exhibits anomalously slow hole capture and is ascribed to the internal interface states of the macropores. For depths beyond the pore region, other deep levels, associated with point defects—possibly metal contamination during the high-temperature annealing step under H2 ambient--have been observed. The impact of the observed defects on the lifetime of thin-film solar cells, fabricated using macropore-based layer transfer is discussed. Finally, it is shown that the presence of pores in the depletion region, which also affects the DLT-spectrum, alters the capacitance-voltage characteristics.

  18. Large area growth and electrical properties of p-type WSe2 atomic layers.

    Science.gov (United States)

    Zhou, Hailong; Wang, Chen; Shaw, Jonathan C; Cheng, Rui; Chen, Yu; Huang, Xiaoqing; Liu, Yuan; Weiss, Nathan O; Lin, Zhaoyang; Huang, Yu; Duan, Xiangfeng

    2015-01-14

    Transition metal dichacogenides represent a unique class of two-dimensional layered materials that can be exfoliated into single or few atomic layers. Tungsten diselenide (WSe(2)) is one typical example with p-type semiconductor characteristics. Bulk WSe(2) has an indirect band gap (∼ 1.2 eV), which transits into a direct band gap (∼ 1.65 eV) in monolayers. Monolayer WSe(2), therefore, is of considerable interest as a new electronic material for functional electronics and optoelectronics. However, the controllable synthesis of large-area WSe(2) atomic layers remains a challenge. The studies on WSe(2) are largely limited by relatively small lateral size of exfoliated flakes and poor yield, which has significantly restricted the large-scale applications of the WSe(2) atomic layers. Here, we report a systematic study of chemical vapor deposition approach for large area growth of atomically thin WSe(2) film with the lateral dimensions up to ∼ 1 cm(2). Microphotoluminescence mapping indicates distinct layer dependent efficiency. The monolayer area exhibits much stronger light emission than bilayer or multilayers, consistent with the expected transition to direct band gap in the monolayer limit. The transmission electron microscopy studies demonstrate excellent crystalline quality of the atomically thin WSe(2). Electrical transport studies further show that the p-type WSe(2) field-effect transistors exhibit excellent electronic characteristics with effective hole carrier mobility up to 100 cm(2) V(-1) s(-1) for monolayer and up to 350 cm(2) V(-1) s(-1) for few-layer materials at room temperature, comparable or well above that of previously reported mobility values for the synthetic WSe(2) and comparable to the best exfoliated materials.

  19. The effect of Gd doping on the atomic and electronic structure of HfO2 thin films.

    Science.gov (United States)

    Ketsman, Ihor; Sokolov, Andrei; Belashchenko, Kirill; Dowben, Peter; Losovyj, Yaroslav; Tang, Jinke; Wang, Zhenjun

    2008-03-01

    HfO2 is a promising oxide for many applications, including high-k gate dielectric for CMOS devices. In addition, Gd-doped HfO2 could lead to a dilute magnetic semiconductor and provide an efficient neutron detection medium due to huge neutron absorption cross section of Gd. Gd-doped HfO2 films deposited on both p-type and n-type silicon by PLD retain monoclinic phase at small doping levels, but can be stabilized in fluorite phase by increased doping [1]. At small doping levels, photoemission measurements indicate n-type character of the films as a result of overcompensation with oxygen vacancies. Depending on a doping level, the films form heterojunctions with good rectifying properties on n- or p-type silicon. Preliminary results show the potential ability of the formed diode structures to detect neutrons. [1] Ya.B.Losovyj, I.Ketsman et al.,APL, 91, 132908, (2007)

  20. 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

    This thesis reports on low temperature amorphous silicon back and front contacts for high-efficiency crystalline silicon solar cells with a p-type base. The back contact uses a sequence of intrinsic amorphous (i-a-Si:H) and boron doped microcrystalline (p-{mu}c-Si:H) silicon layers fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD) and a magnetron sputtered ZnO:Al layer. The back contact is finished by evaporating Al onto the ZnO:Al and altogether prepared at a maximum temperature of 220 C. Analysis of the electronic transport of mobile charge carriers at the back contact shows that the two high-efficiency requirements low back contact series resistance and high quality c-Si surface passivation are in strong contradiction to each other, thus difficult to achieve at the same time. The preparation of resistance- and effective lifetime samples allows one to investigate both requirements independently. Analysis of the majority charge carrier transport on complete Al/ZnO:Al/a-Si:H/c-Si back contact structures derives the resistive properties. Measurements of the effective minority carrier lifetime on a-Si:H coated wafers determines the back contact surface passivation quality. Both high-efficiency solar cell requirements together are analyzed in complete photovoltaic devices where the back contact series resistance mainly affects the fill factor and the back contact passivation quality mainly affects the open circuit voltage. The best cell equipped with a diffused emitter with random texture and a full-area a-Si:H/c-Si back contact has an independently confirmed efficiency {eta} = 21.0 % with an open circuit voltage V{sub oc} = 681 mV and a fill factor FF = 78.7 % on an area of 1 cm{sup 2}. An alternative concept that uses a simplified a-Si:H layer sequence combined with Al-point contacts yields a confirmed efficiency {eta} = 19.3 % with an open circuit voltage V{sub oc} = 655 mV and a fill factor FF = 79.5 % on an area of 2 cm{sup 2}. Analysis of the

  1. 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

    This thesis reports on low temperature amorphous silicon back and front contacts for high-efficiency crystalline silicon solar cells with a p-type base. The back contact uses a sequence of intrinsic amorphous (i-a-Si:H) and boron doped microcrystalline (p-{mu}c-Si:H) silicon layers fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD) and a magnetron sputtered ZnO:Al layer. The back contact is finished by evaporating Al onto the ZnO:Al and altogether prepared at a maximum temperature of 220 C. Analysis of the electronic transport of mobile charge carriers at the back contact shows that the two high-efficiency requirements low back contact series resistance and high quality c-Si surface passivation are in strong contradiction to each other, thus difficult to achieve at the same time. The preparation of resistance- and effective lifetime samples allows one to investigate both requirements independently. Analysis of the majority charge carrier transport on complete Al/ZnO:Al/a-Si:H/c-Si back contact structures derives the resistive properties. Measurements of the effective minority carrier lifetime on a-Si:H coated wafers determines the back contact surface passivation quality. Both high-efficiency solar cell requirements together are analyzed in complete photovoltaic devices where the back contact series resistance mainly affects the fill factor and the back contact passivation quality mainly affects the open circuit voltage. The best cell equipped with a diffused emitter with random texture and a full-area a-Si:H/c-Si back contact has an independently confirmed efficiency {eta} = 21.0 % with an open circuit voltage V{sub oc} = 681 mV and a fill factor FF = 78.7 % on an area of 1 cm{sup 2}. An alternative concept that uses a simplified a-Si:H layer sequence combined with Al-point contacts yields a confirmed efficiency {eta} = 19.3 % with an open circuit voltage V{sub oc} = 655 mV and a fill factor FF = 79.5 % on an area of 2 cm{sup 2}. Analysis of the

  2. Graphene doping methods and device applications.

    Science.gov (United States)

    Oh, Jong Sik; Kim, Kyong Nam; Yeom, Geun Young

    2014-02-01

    Graphene has recently been studied as a promising material to replace and enhance conventional electronic materials in various fields such as electronics, photovoltaics, sensors, etc. However, for the electronic applications of graphene prepared by various techniques such as chemical vapor deposition, chemical exfoliation, mechanical exfoliation, etc., critical limitations are found due to the defects in the graphene in addition to the absence of a semiconducting band gap. For that, many researchers have investigated the doped graphene which is effective to tailor its electronic property and chemical reactivity. This work presents a review of the various graphene doping methods and their device applications. As doping methods, direct synthesis method and post treatment method could be categorized. Because the latter case has been widely investigated and used in various electronic applications, we will focus on the post treatment method. Post treatment method could be further classified into wet and dry doping methods. In the case of wet doping, acid treatment, metal chloride, and organic material coating are the methods used to functionalize graphene by using dip-coating, spin coating, etc. Electron charge transfer achieved from graphene to dopants or from dopants to graphene makes p-type or n-type graphenes, respectively, with sheet resistance reduction effect. In the case of dry doping, it can be further categorized into electrostatic field method, evaporation method, thermal treatment method, plasma treatment method, etc. These doping techniques modify Fermi energy level of graphene and functionalize the property of graphene. Finally, some perspectives and device applications of doped graphene are also briefly discussed.

  3. Effect of Split Gate Size on the Electrostatic Potential and 0.7 Anomaly within Quantum Wires on a Modulation-Doped GaAs /AlGaAs Heterostructure

    Science.gov (United States)

    Smith, L. W.; Al-Taie, H.; Lesage, A. A. J.; Thomas, K. J.; Sfigakis, F.; See, P.; Griffiths, J. P.; Farrer, I.; Jones, G. A. C.; Ritchie, D. A.; Kelly, M. J.; Smith, C. G.

    2016-04-01

    We study 95 split gates of different size on a single chip using a multiplexing technique. Each split gate defines a one-dimensional channel on a modulation-doped GaAs /AlGaAs heterostructure, through which the conductance is quantized. The yield of devices showing good quantization decreases rapidly as the length of the split gates increases. However, for the subset of devices showing good quantization, there is no correlation between the electrostatic length of the one-dimensional channel (estimated using a saddle-point model) and the gate length. The variation in electrostatic length and the one-dimensional subband spacing for devices of the same gate length exceeds the variation in the average values between devices of different lengths. There is a clear correlation between the curvature of the potential barrier in the transport direction and the strength of the "0.7 anomaly": the conductance value of the 0.7 anomaly reduces as the barrier curvature becomes shallower. These results highlight the key role of the electrostatic environment in one-dimensional systems. Even in devices with clean conductance plateaus, random fluctuations in the background potential are crucial in determining the potential landscape in the active device area such that nominally identical gate structures have different characteristics.

  4. An aqueous solution-based doping strategy for large-scale synthesis of Sb-doped ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Wang Fei; Bayerl, Dylan; Shi Jian; Wang Xudong [Department of Materials Science and Engineering, University of Wisconsin at Madison (United States); Seo, Jung-Hun; Mi Hongyi; Ma Zhenqiang [Department of Electrical and Computer Engineering, University of Wisconsin at Madison (United States); Zhao Deyin; Shuai Yichen; Zhou Weidong, E-mail: xudong@engr.wisc.edu [Department of Electrical Engineering, University of Texas at Arlington (United States)

    2011-06-03

    An aqueous solution-based doping strategy was developed for controlled doping impurity atoms into a ZnO nanowire (NW) lattice. Through this approach, antimony-doped ZnO NWs were successfully synthesized in an aqueous solution containing zinc nitrate and hexamethylenetetramine with antimony acetate as the dopant source. By introducing glycolate ions into the solution, a soluble antimony precursor (antimony glycolate) was formed and a good NW morphology with a controlled antimony doping concentration was successfully achieved. A doping concentration study suggested an antimony glycolate absorption doping mechanism. By fabricating and characterizing NW-based field effect transistors (FETs), stable p-type conductivity was observed. A field effect mobility of 1.2 cm{sup 2} V{sup -1} s{sup -1} and a carrier concentration of 6 x 10{sup 17} cm{sup -3} were achieved. Electrostatic force microscopy (EFM) characterization on doped and undoped ZnO NWs further illustrated the shift of the metal-semiconductor barrier due to Sb doping. This work provided an effective large-scale synthesis strategy for doping ZnO NWs in aqueous solution.

  5. Electronic properties of embedded graphene: doped amorphous silicon/CVD graphene heterostructures

    Science.gov (United States)

    Arezki, Hakim; Boutchich, Mohamed; Alamarguy, David; Madouri, Ali; Alvarez, José; Cabarrocas, Pere Roca i.; Kleider, Jean-Paul; Yao, Fei; Lee, Young Hee

    2016-10-01

    Large-area graphene film is of great interest for a wide spectrum of electronic applications, such as field effect devices, displays, and solar cells, among many others. Here, we fabricated heterostructures composed of graphene (Gr) grown by chemical vapor deposition (CVD) on copper substrate and transferred to SiO2/Si substrates, capped by n- or p-type doped amorphous silicon (a-Si:H) deposited by plasma-enhanced chemical vapor deposition. Using Raman scattering we show that despite the mechanical strain induced by the a-Si:H deposition, the structural integrity of the graphene is preserved. Moreover, Hall effect measurements directly on the embedded graphene show that the electronic properties of CVD graphene can be modulated according to the doping type of the a-Si:H as well as its phase i.e. amorphous or nanocrystalline. The sheet resistance varies from 360 Ω sq-1 to 1260 Ω sq-1 for the (p)-a-Si:H/Gr (n)-a-Si:H/Gr, respectively. We observed a temperature independent hole mobility of up to 1400 cm2 V-1 s-1 indicating that charge impurity is the principal mechanism limiting the transport in this heterostructure. We have demonstrated that embedding CVD graphene under a-Si:H is a viable route for large scale graphene based solar cells or display applications.

  6. 2D coherent charge transport in highly ordered conducting polymers doped by solid state diffusion

    Science.gov (United States)

    Kang, Keehoon; Watanabe, Shun; Broch, Katharina; Sepe, Alessandro; Brown, Adam; Nasrallah, Iyad; Nikolka, Mark; Fei, Zhuping; Heeney, Martin; Matsumoto, Daisuke; Marumoto, Kazuhiro; Tanaka, Hisaaki; Kuroda, Shin-Ichi; Sirringhaus, Henning

    2016-08-01

    Doping is one of the most important methods to control charge carrier concentration in semiconductors. Ideally, the introduction of dopants should not perturb the ordered microstructure of the semiconducting host. In some systems, such as modulation-doped inorganic semiconductors or molecular charge transfer crystals, this can be achieved by spatially separating the dopants from the charge transport pathways. However, in conducting polymers, dopants tend to be randomly distributed within the conjugated polymer, and as a result the transport properties are strongly affected by the resulting structural and electronic disorder. Here, we show that in the highly ordered lamellar microstructure of a regioregular thiophene-based conjugated polymer, a small-molecule p-type dopant can be incorporated by solid state diffusion into the layers of solubilizing side chains without disrupting the conjugated layers. In contrast to more disordered systems, this allows us to observe coherent, free-electron-like charge transport properties, including a nearly ideal Hall effect in a wide temperature range, a positive magnetoconductance due to weak localization and the Pauli paramagnetic spin susceptibility.

  7. Electrical property studies on chemically processed polypyrolle/aluminum doped ZnO based hybrid heterostructures

    Science.gov (United States)

    Mohan Kumar, G.; Ilanchezhiyan, P.; Madhan Kumar, A.; Yuldashev, Sh. U.; Kang, T. W.

    2016-04-01

    A hybrid structure based on p-type polypyrolle (PPy) and n-type aluminum (Al) doped ZnO nanorods was successfully constructed. The effect of Al doping on material properties of wurtzite structured ZnO were studied using several analytical techniques. To establish the desired hybrid structure, pyrrole monomers were polymerized on hydrothermally grown Al doped ZnO nanorods by chemical polymerization. The current⿿voltage characteristics on the fabricated PPy/Al doped ZnO heterostructures were found to exhibit excellent rectifying characteristics under dark and illumination conditions. The obtained results augment the prescribed architecture to be highly suitable for high-sensitivity optoelectronic applications.

  8. Te-doped cadmium telluride films fabricated by close spaced sublimation

    Science.gov (United States)

    Li, J.; Zheng, Y. F.; Xu, J. B.; Dai, K.

    2003-07-01

    Te-doped cadmium telluride (CdTe) films were deposited on ITO/glass substrates using the close spaced sublimation (CSS) method. The films were characterized by x-ray diffraction (XRD), the x-ray fixed-quantity (XRF) method, scanning electron microscopy (SEM) and the Hall effect. The XRD and SEM results show that appropriate Te doping would be favourable to the growth of CdTe crystallite. The Hall effect measurements indicate that the conductivity of CdTe films could be dramatically improved by Te doping. The work presented here suggests that p-type doping CdTe films can be produced using this deposition method.

  9. p Doping in Expanded Phases of ZnO: An Ab Initio Study

    Science.gov (United States)

    Hapiuk, D.; Marques, Miguel A. L.; Melinon, P.; Flores-Livas, José A.; Botti, Silvana; Masenelli, B.

    2012-03-01

    The issue of p doping in nanostructured cagelike ZnO is investigated by state-of-the-art calculations. Our study is focused on one prototypical structure, namely, sodalite, for which we show that p-type doping is possible for elements of the V, VI, and VII columns of the periodic table. However, some dopants tend to form dimers, thus impairing the stability of this kind of doping. This difference of behavior is discussed, and two criteria are proposed to ensure stable p doping.

  10. Sputtering deposition of P-type SnO films with SnO₂ target in hydrogen-containing atmosphere.

    Science.gov (United States)

    Hsu, Po-Ching; Hsu, Chao-Jui; Chang, Ching-Hsiang; Tsai, Shiao-Po; Chen, Wei-Chung; Hsieh, Hsing-Hung; Wu, Chung-Chih

    2014-08-27

    In this work, we had investigated sputtering deposition of p-type SnO using the widely used and robust SnO2 target in a hydrogen-containing reducing atmosphere. The effects of the hydrogen-containing sputtering gas on structures, compositions, optical, and electrical properties of deposited SnOx films were studied. Results show that polycrystalline and SnO-dominant films could be readily obtained by carefully controlling the hydrogen gas ratio in the sputtering gas and the extent of reduction reaction. P-type conductivity was unambiguously observed for SnO-dominant films with traceable Sn components, exhibiting a p-type Hall mobility of up to ∼3 cm(2) V(-1) s(-1). P-type SnO thin-film transistors using such SnO-dominant films were also demonstrated.

  11. 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.

  12. 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.

  13. Relevance of the selective oestrogen receptor modulators tamoxifen, toremifene and clomiphene in doping field: endogenous steroids urinary profile after multiple oral doses.

    Science.gov (United States)

    Mazzarino, Monica; Braganò, Maria Cristina; de la Torre, Xavier; Molaioni, Francesco; Botrè, Francesco

    2011-11-01

    The present study was performed to investigate the influence of the intake of selective oestrogen receptor modulators on the urinary endogenous steroids profile. For this purpose the circadian variability of luteinizing hormone, follicle-stimulating hormone, testosterone, 5α-androstan-3α,17β-diol, 5β-androstan-3α,17β-diol, epitestosterone, 4-androstenedione, androsterone and etiocholanolone were measured on eight subjects (four males and four females) by gas chromatography-mass spectrometry and chemiluminescent immunometric assay techniques before and after oral administration of multiple doses of either tamoxifen (80 mg for 2 days) or toremifene (120 mg for 2 days) or clomiphene (100 mg for 2 days). The individual baseline variability of the steroids studied was set up by collecting the urine samples every 3 h, for 3 days prior to the treatment; whereas the evaluation of the effects of the oral administration of multiple doses of selective oestrogen receptor modulators on the steroid urinary profile was assessed by collecting urine samples every three hours for at least five days from the first administration. The results of our measurements showed that, only in male subjects, the relative urinary concentrations of testosterone, epitestosterone and 4-androstenedione were significantly altered generally after the second day of drug administration. While no significant effects were recorded in both sexes on the luteinizing hormone, follicle-stimulating hormone, androsterone, etiocholanolone, 5α-androstan-3α,17β-diol and 5β-androstan-3α,17β-diol urinary levels and on testosterone/epitestosterone, 5α-androstan-3α,17β-diol/5β-androstan-3α,17β-diol and androsterone/etiocholanolone ratios. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. P-type Planet–Planet Scattering: Kepler Close Binary Configurations

    Science.gov (United States)

    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.

  15. 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.

  16. Evidence for an iron-hydrogen complex in p-type silicon

    Science.gov (United States)

    Leonard, S.; Markevich, V. P.; Peaker, A. R.; Hamilton, B.; Murphy, J. D.

    2015-07-01

    Interactions of hydrogen with iron have been studied in Fe contaminated p-type Czochralski silicon using capacitance-voltage profiling and deep level transient spectroscopy (DLTS). Hydrogen has been introduced into the samples from a silicon nitride layer grown by plasma enhanced chemical vapor deposition. After annealing of the Schottky diodes on Si:Fe + H samples under reverse bias in the temperature range of 90-120 °C, a trap has been observed in the DLTS spectra which we have assigned to a Fe-H complex. The trap is only observed when a high concentration of hydrogen is present in the near surface region. The trap concentration is higher in samples with a higher concentration of single interstitial Fe atoms. The defect has a deep donor level at Ev + 0.31 eV. Direct measurements of capture cross section of holes have shown that the capture cross section is not temperature dependent and its value is 5.2 × 10-17 cm2. It is found from an isochronal annealing study that the Fe-H complex is not very stable and can be eliminated completely by annealing for 30 min at 125 °C.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hassen, M. [Institut National de Recherche Scientifique et Technique, Laboratoire de Photovoltaique et des Semiconducteurs, PB 95 2050 Hammam-Lif (Tunisia); Ben Jaballah, A. [Institut National de Recherche Scientifique et Technique, Laboratoire de Photovoltaique et des Semiconducteurs, PB 95 2050 Hammam-Lif (Tunisia)]. E-mail: gadour2003@yahoo.fr; Hajji, M. [Institut National de Recherche Scientifique et Technique, Laboratoire de Photovoltaique et des Semiconducteurs, PB 95 2050 Hammam-Lif (Tunisia); Rahmouni, H. [Laboratoire de Physique des Semiconducteurs et des Composants Electroniques, Faculte des Sciences de Monastir, Rue de Kairouan, 5000 Monastir (Tunisia); Selmi, A. [Laboratoire de Physique des Semiconducteurs et des Composants Electroniques, Faculte des Sciences de Monastir, Rue de Kairouan, 5000 Monastir (Tunisia); Ezzaouia, H. [Institut National de Recherche Scientifique et Technique, Laboratoire de Photovoltaique et des Semiconducteurs, PB 95 2050 Hammam-Lif (Tunisia)

    2005-12-05

    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 {mu}m) are thermally evaporated followed by photo-thermal annealing treatments in N{sub 2} atmosphere at one of several temperatures ranging between 600 and 800 deg. C. In the second type, phosphorus is continually diffused in N{sub 2}/O{sub 2} ambient in a solid phase from POCl{sub 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{sup 2} V{sup -1} s{sup -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.

  18. P-type InGaAsP coolers for integrated optic devices

    Science.gov (United States)

    Vashaee, Daryoosh; LaBounty, Christopher J.; Fang, Xiaofeng; Zeng, Gehong; Abraham, Patrick; Bowers, John E.; Shakouri, Ali

    2001-05-01

    Single stage thin film coolers based on thermoelectric and thermionic cooling in p-type InGaAsP superlattice structures have been fabricated. Devices with different sizes and at various ambient temperatures have been characterized. Experimental results showed 0.5 degree centigrade cooling below the ambient temperature at 25C. This cooling over 1 4mu2m thick superlattice barrier corresponds to cooling power densities on the order of 200 W/cm2. The device cools by a factor of two better at higher temperatures (70C). This is due to the reduction of the superlattice thermal conductivity and the broadening of the electronic distribution function at higher temperatures. 150x150 micrometers 2 devices provide largest cooling at room temperature while the optimum device size shrinks as the temperature increases. Simulations results that take into account finite thermal resistance of the InP substrate, the effect of the contact resistance, heat generation in the wire-bonds and metallic pads on top of the device predict accurately the optimum cooling of these micro refrigerators. By eliminating the major parasitic sources of heating (Joule heating in the substrate, heat conduction through the side contact and reducing the contact resistance to 5x7-7 ohm-cm2) simulations show that, ultimately, one can achieve 15 degree(s)C cooling (10's of kW/cm2 cooling power) with single stage p-InGaAsP thin film coolers.

  19. Structural change and power factor enhancement of thermoelectric p-type films

    Energy Technology Data Exchange (ETDEWEB)

    Rothe, Katrin; Leipner, Hartmut; Heyroth, Frank [Interdisziplinaeres Zentrum fuer Materialwissenschaften, Martin-Luther-Universitaet 06099 Halle (Germany); Stordeur, Matthias; Engers, Bernd [angaris GmbH, Heinrich-Damerow-Str. 1, 06120 Halle (Germany)

    2008-07-01

    By sputter-deposition thin films of the thermoelectric effective p-type compound semiconductor (Bi{sub 0.15}Sb{sub 0.85}){sub 2}Te{sub 3} were prepared. For the first time a distinct increase of the electrical conductivity s was observed after heating of the as-deposited films and afterwards cooling. For the enlightenment of this typical behavior, which seems to be similar found for phase change materials consisting of (Ge, Sb, Te)-alloys, also the Seebeck (S) and the Hall coefficient were measured. It was established that the increase of the electrical conductivity is not connected with an expected decrease of the Seebeck coefficient, because the charge carrier density is reduced but at the same time the hole mobility is increasing. Corresponding analytical investigations by XRD, EDX, and REM shows that besides a grain growth in the polycrystalline films a Te-rich phase appears after the heat treatment. The increase of the electrical conductivity at nearly unchanged Seebeck coefficient can be exploited for the enhancement of the film power factor (S{sup 2}s). This is important for the efficiency of thermoelectric thin films devices as miniaturized coolers, generators, and sensors. Nevertheless for a quantitative interpretation of the presented new experimental results further investigations and theoretical considerations are required.

  20. Enhanced thermoelectric figure of merit of p-type half-Heuslers.

    Science.gov (United States)

    Yan, Xiao; Joshi, Giri; Liu, Weishu; Lan, Yucheng; Wang, Hui; Lee, Sangyeop; Simonson, J W; Poon, S J; Tritt, T M; Chen, Gang; Ren, Z F

    2011-02-01

    Half-Heuslers would be important thermoelectric materials due to their high temperature stability and abundance if their dimensionless thermoelectric figure of merit (ZT) could be made high enough. The highest peak ZT of a p-type half-Heusler has been so far reported about 0.5 due to the high thermal conductivity. Through a nanocomposite approach using ball milling and hot pressing, we have achieved a peak ZT of 0.8 at 700 °C, which is about 60% higher than the best reported 0.5 and might be good enough for consideration for waste heat recovery in car exhaust systems. The improvement comes from a simultaneous increase in Seebeck coefficient and a significant decrease in thermal conductivity due to nanostructures. The samples were made by first forming alloyed ingots using arc melting and then creating nanopowders by ball milling the ingots and finally obtaining dense bulk by hot pressing. Further improvement in ZT is expected when average grain sizes are made smaller than 100 nm.