WorldWideScience

Sample records for pt-si schottky barrier

  1. External quantum efficiency-enhanced PtSi Schottky-barrier detector utilizing plasmonic ZnO:Al nanoparticles and subwavelength gratings

    Institute of Scientific and Technical Information of China (English)

    Bingxin Kang; Yi Cai; Lingxue Wang

    2016-01-01

    A infrared light trapping structure combining front subwavelength gratings and rear ZnO:Al nanoparticles for a PtSi Schottky-barrier detector over a 3-5 μm waveband is theoretically investigated.By selecting the proper plasmonic material and optimizing the parameters for the proposed structure,the absorption of the PtSi layer is dramatically improved.The theoretical results show that this improvement eventually translates into an equivalent external quantum efficiency (EQE) enhancement of 2.46 times at 3-3.6 μm and 2.38 times at 3.6-5 μm compared to conventional structures.This improvement in the EQE mainly lies in the increase of light path lengths within the PtSi layer by the subwavelength grating diffraction and nanoparticle-scattering effects.

  2. High Performance P-Channel Schottky Barrier MOSFETs with Self-Aligned PtSi Source/Drain on Thin Film SOI Substrate

    Institute of Scientific and Technical Information of China (English)

    ZHU Shi-Yang; LI Ming-Fu

    2005-01-01

    @@ P-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) with PtSi Schottky barrier source/drain, high-k gate dielectric and metal gate electrode were fabricated on a thin p-type silicon-on-insulator (SOI) substrateusing a simplified low temperature process. The device works on a fully-depleted accumulation-mode and hasan excellent electrical performance. It reaches Ion/Ioff ratio of about 107, subthreshold swing of 65mV/decade and saturation drain current of Ids= 8.8μA/μm at |Vg - Vth| = |Vd| = 1 V for devices with the channel length 4.0μm and the equivalent oxide thickness 2.0nm. Compared to the corresponding bulk-Si counterparts, SOI p-SBMOSFETs have smaller off-state current due to reduction of the PtSi/Si contact area.

  3. Hydrogen-Sensing Behaviors of Pd-and Pt-SiC Schottky Diodes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chang Kyo; Lee, Joo Hun; Hong, Chin Soo [Soonchunhyang University (Korea); Cho, Nam Ihn [Sunmoon University (Korea)

    2000-07-01

    Hydrogen-sensing behaviors of Pd-and Pt-SiC Schottky diodes, fabricated on the same SiC substrate, have been systematically compared and analyzed as a function of hydrogen concentration and temperature by I-V and {delta}I-t methods under steady-state and transient conditions. The effects of hydrogen adsorption on the device parameters such as the barrier height are investigated. The significant differences in their hydrogen sensing characteristics have been examined in terms of sensitivity limit, linearity of response, response rate, and response time. For the investigated temperature range, Pd-SiC Schottky diode shows better performance for H{sub 2} detection than Pt-SiC Schottky diode under the same testing conditions. The physical and chemical mechanisms responsible for hydrogen detection are discussed. Analysis of the steady-state reaction kinetics using I-V method confirmed that the atomistic hydrogen process is responsible for the barrier height change in the diodes. (author). 16 refs., 10 figs.

  4. Doping-Spike PtSi Schottky Infrared Detectors with Extended Cutoff Wavelengths

    Science.gov (United States)

    Lin, T. L.; Park, J. S.; Gunapala, S. D.; Jones, E. W.; Castillo, H. M. Del

    1994-01-01

    A technique incorporating a p+ doping spike at the silicide/Si interface to reduce the effective Schottky barrier of the silicide infrared detectors and thus extend the cutoff wavelength has been developed.

  5. Silicon Carbide Schottky Barrier Diode

    Science.gov (United States)

    Zhao, Jian H.; Sheng, Kuang; Lebron-Velilla, Ramon C.

    2004-01-01

    This chapter reviews the status of SiC Schottky barrier diode development. The fundamental of Schottky barrier diodes is first provided, followed by the review of high-voltage SiC Schottky barrier diodes, junction-barrier Schottky diodes, and merged-pin-Schottky diodes. The development history is reviewed ad the key performance parameters are discussed. Applications of SiC SBDs in power electronic circuits as well as other areas such as gas sensors, microwave and UV detections are also presented, followed by discussion of remaining challenges.

  6. Analysis of frequency- and temperature-dependent interface states in PtSi/p-Si Schottky diodes

    Energy Technology Data Exchange (ETDEWEB)

    Sellai, A. [Physics Department, P.O. Box 36, Sultan Qaboos University 123, Muscat (Oman)], E-mail: asellai@squ.edu.om; Ouennoughi, Z. [Laboratoire Optoelectronique et Composants, Departement de Physique UFAS Setif Algerie (Algeria)

    2008-12-05

    To yield quantitative information about their interface states, PtSi/p-Si Schottky structures have been studied using conductance and capacitance measurements over a wide range of frequencies (1 kHz to 1 MHz) and at several temperatures (80-140 K). The increase in capacitance at lower frequencies is seen as a signature of interface states, the densities of which are evaluated to be of the order of {approx}10{sup 12} eV{sup -1} cm{sup -2}. The presence of interface states is also evidenced as a peak in the conductance-frequency characteristics that increases in magnitude with decreasing temperatures. The variations of interface conductance are best described by an analytical equation derived assuming an energy-dependent cross-section of these interface states. The conductance data is subsequently used to extract the relaxation times of interface states and their energy distribution with respect to the top of the valence band. Relaxation times, in particular, while temperature dependent with an average value of {approx}4 {mu}s, show a noticeably weak dependence on bias.

  7. Observation and Measurement of Negative Differential Resistance on PtSi Schottky Junctions on Porous Silicon

    Directory of Open Access Journals (Sweden)

    Mansor Mohtashamifar

    2010-01-01

    Full Text Available Nanosize porous Si is made by two step controlled etching of Si. The first etching step is carried on the Si surface and the second is performed after deposition of 75 Å of platinum on the formed surface. A platinum silicide structure with a size of less than 25 nm is formed on the porous Si surface, as measured with an Atomic Forced Microscope (AFM. Differential resistance curve as a function of voltage in 77 K and 100 K shows a negative differential resistance and indicates the effect of quantum tunneling. In general form, the ratio of maximum to minimum tunneling current (PVR and the number of peaks in I-V curves reduces by increasing the temperature. However, due to accumulation of carriers behind the potential barrier and superposition of several peaks, it is observed that the PVR increases at 100 K and the maximum PVR at 100 K is 189.6.

  8. Plastic Schottky barrier solar cells

    Science.gov (United States)

    Waldrop, James R.; Cohen, Marshall J.

    1984-01-24

    A photovoltaic cell structure is fabricated from an active medium including an undoped, intrinsically p-type organic semiconductor comprising polyacetylene. When a film of such material is in rectifying contact with a magnesium electrode, a Schottky-barrier junction is obtained within the body of the cell structure. Also, a gold overlayer passivates the magnesium layer on the undoped polyacetylene film.

  9. PtSi Clustering in Silicon Probed by Transport Spectroscopy

    Directory of Open Access Journals (Sweden)

    Massimo Mongillo

    2013-12-01

    Full Text Available Metal silicides formed by means of thermal annealing processes are employed as contact materials in microelectronics. Control of the structure of silicide/silicon interfaces becomes a critical issue when the characteristic size of the device is reduced below a few tens of nanometers. Here, we report on silicide clustering occurring within the channel of PtSi/Si/PtSi Schottky-barrier transistors. This phenomenon is investigated through atomistic simulations and low-temperature resonant-tunneling spectroscopy. Our results provide evidence for the segregation of a PtSi cluster with a diameter of a few nanometers from the silicide contact. The cluster acts as a metallic quantum dot giving rise to distinct signatures of quantum transport through its discrete energy states.

  10. New Type Far IR and THz Schottky Barrier Detectors for Scientific and Civil Application

    Directory of Open Access Journals (Sweden)

    V. G. Ivanov

    2011-01-01

    Full Text Available The results of an experimental investigation into a new type of VLWIR detector based on hot electron gas emission and architecture of the detector are presented and discussed. The detectors (further referred to as HEGED take advantage of the thermionic emission current change effect in a semiconductor diode with a Schottky barrier (SB as a result of the direct transfer of the absorbed radiation energy to the system of electronic gas in the quasimetallic layer of the barrier. The possibility of detecting radiation having the energy of quantums less than the height of the Schottky diode potential barrier and of obtaining a substantial improvement of a cutoff wavelength to VLWIR of the PtSi/Si detector has been demonstrated. The complementary contribution of two physical mechanisms of emanation detection—“quantum” and hot electrons gas emission—has allowed the creation of a superwideband IR detector using standard silicon technology.

  11. Plastic Schottky-barrier solar cells

    Science.gov (United States)

    Waldrop, J.R.; Cohen, M.J.

    1981-12-30

    A photovoltaic cell structure is fabricated from an active medium including an undoped polyacetylene, organic semiconductor. When a film of such material is in rectifying contact with a metallic area electrode, a Schottky-barrier junction is obtained within the body of the cell structure. Also, a gold overlayer passivates a magnesium layer on the undoped polyacetylene film. With the proper selection and location of elements a photovoltaic cell structure and solar cell are obtained.

  12. Radioisotope battery using Schottky barrier devices

    Energy Technology Data Exchange (ETDEWEB)

    Manasse, F.K. (Drexel Univ., Philadelphia); Tse, A.N.

    1976-05-01

    Based on the well-known betavoltaic effect, a new nuclear battery, which uses a Schottky barrier, has been used in place of the more standard p-n junction diode, along with /sup 147/Pm metal film rather than Pm/sub 2/O/sub 3/ oxide, as in the commercially available Betacel. Measurement of absorption, conversion efficiency, thickness, etc., as functions of resistivity and other cell parameters, and assessment of performance are being researched to design a prototype battery.

  13. Optimum Barrier Height for SiC Schottky Barrier Diode

    OpenAIRE

    Mohamed Abd El-Latif; Alaa El-Din Sayed Hafez

    2013-01-01

    The study of barrier height control and optimization for Schottky barrier diode (SBD) from its physical parameters have been introduced using particle swarm optimization (PSO) algorithm. SBD is the rectifying barrier for electrical conduction across the metal semiconductor (MS) junction and, therefore, is of vital importance to the successful operation of any semiconductor device. 4H-SiC is used as a semiconductor material for its good electrical characteristics with high-power semiconductor ...

  14. Graphene applications in Schottky barrier solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lancellotti, L., E-mail: laura.lancellotti@enea.it [ENEA Research Centre Portici, Piazzale E. Fermi 1, 80055 Portici (Napoli) (Italy); Polichetti, T.; Ricciardella, F. [ENEA Research Centre Portici, Piazzale E. Fermi 1, 80055 Portici (Napoli) (Italy); Tari, O., E-mail: orlando.tari@unina.it [University of Naples ' Federico II' , Dept. of Electronic Engineering, Via Claudio 21, 80125 Napoli (Italy); Gnanapragasam, S. [ENEA Research Centre Portici, Piazzale E. Fermi 1, 80055 Portici (Napoli) (Italy); Daliento, S. [University of Naples ' Federico II' , Dept. of Electronic Engineering, Via Claudio 21, 80125 Napoli (Italy); Di Francia, G. [ENEA Research Centre Portici, Piazzale E. Fermi 1, 80055 Portici (Napoli) (Italy)

    2012-11-01

    We report a theoretical study about the performances of graphene on semiconductor Schottky barrier solar cells with the aim to show the potentiality of this kind of device. The simulations are carried by a generalized equivalent circuit model, where the circuital parameters are strictly dependent on the physical properties of the graphene and semiconductor which form the Schottky junction. We have realized graphene samples and characterized them by optical and atomic force microscopy, and Raman spectroscopy. Capacitance-voltage measurements have been made on some 'ad hoc' graphene based devices in order to obtain graphene workfunction, a very essential physical parameter. The estimated value is compatible with four layer graphene. This result is in agreement with the morphological characterizations of our material. - Highlights: Black-Right-Pointing-Pointer An equivalent circuit model simulates graphene based Schottky barrier solar cells. Black-Right-Pointing-Pointer Graphene flakes are identified through Raman spectroscopy and Atomic Force Microscopy. Black-Right-Pointing-Pointer Workfunction estimation by Capacitance-Voltage (C-V) on graphene based devices Black-Right-Pointing-Pointer A multilayered structure is evidenced by morphological and C-V characterization.

  15. A novel nanoscaled Schottky barrier based transmission gate and its digital circuit applications

    Science.gov (United States)

    Kumar, Sunil; Loan, Sajad A.; Alamoud, Abdulrahman M.

    2017-04-01

    In this work we propose and simulate a compact nanoscaled transmission gate (TG) employing a single Schottky barrier based transistor in the transmission path and a single transistor based Sajad-Sunil-Schottky (SSS) device as an inverter. Therefore, just two transistors are employed to realize a complete transmission gate which normally consumes four transistors in the conventional technology. The transistors used to realize the transmission path and the SSS inverter in the proposed TG are the double gate Schottky barrier devices, employing stacks of two metal silicides, platinum silicide (PtSi) and erbium silicide (ErSi). It has been observed that the realization of the TG gate by the proposed technology has resulted into a compact structure, with reduced component count, junctions, interconnections and regions in comparison to the conventional technology. The further focus of this work is on the application part of the proposed technology. So for the first time, the proposed technology has been used to realize various combinational circuits, like a two input AND gate, a 2:1 multiplexer and a two input XOR circuits. It has been observed that the transistor count has got reduced by half in a TG, two input AND gate, 2:1 multiplexer and in a two input XOR gate. Therefore, a significant reduction in transistor count and area requirement can be achieved by using the proposed technology. The proposed technology can be also used to perform the compact realization of other combinational and sequential circuitry in future.

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

    Science.gov (United States)

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

    2016-03-01

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

  17. Enhanced Plasmonic Light Absorption for Silicon Schottky-Barrier Photodetectors

    DEFF Research Database (Denmark)

    Hashemi, Mahdieh; Farzad, Mahmood Hosseini; Mortensen, N. Asger;

    2013-01-01

    Quantum efficiency of the silicon Schottky-barrier photodetector is limited by the weak interaction between the photons and electrons in the metal. By engineering the metal surfaces, metallic groove structures are proposed to achieve strong light absorption in the metal, where most of the energy...... is transferred into hot carriers near the Schottky barrier. The proposed broadband photodetector with a bi-grating metallic structure on the silicon substrate enables to absorb 76 % of the infrared light in the metal with a 200-nm bandwidth, while staying insensitive to the incident angle. These results pave...... a new promising way to attain high quantum efficiency silicon Schottky-barrier photodetectors....

  18. Measuring Schottky barrier height at graphene/SiC junction

    Science.gov (United States)

    Tomer, D.; Hudy, L.; Rajput, S.; Li, L.

    2014-03-01

    When graphene is interfaced with a semiconductor, a Schottky junction forms with rectifying properties. In this work, we measured the Schottky barrier heights of graphene/SiC Schottky diodes using current-voltage (I-V) measurement. Chemical vapor deposited graphene was transferred onto semiconductor surfaces of opposite polarization: the hydrogen-terminated Si- and C-faces of α-SiC, which was confirmed by Raman spectroscopy and scanning tunneling microscopy. The Schottky barrier height is found to be sensitive to the polarization of the substrate and surface preparation. On the Si-face, a barrier of 0.47 eV is found. These results will be compared with earlier work as well as our in situ scanning tunneling spectroscopy results. Supported by DOE (DE-FG02-07ER46228).

  19. Physical based Schottky barrier diode modeling for THz applications

    DEFF Research Database (Denmark)

    Yan, Lei; Krozer, Viktor; Michaelsen, Rasmus Schandorph;

    2013-01-01

    In this work, a physical Schottky barrier diode model is presented. The model is based on physical parameters such as anode area, Ohmic contact area, doping profile from epitaxial (EPI) and substrate (SUB) layers, layer thicknesses, barrier height, specific contact resistance, and device...... temperature. The effects of barrier height lowering, nonlinear resistance from the EPI layer, and hot electron noise are all included for accurate characterization of the Schottky diode. To verify the diode model, measured I-V and C-V characteristics are compared with the simulation results. Due to the lack...

  20. Boron implantation effects on Au:GaAs Schottky barrier

    Energy Technology Data Exchange (ETDEWEB)

    Perez, A.; Roura, P.; Esteve, J.; Altelarrea, H.; Anton, J.A.; Cornet, A.; Morante, J.R.

    1987-01-01

    In this work, we analyse the use of boron implantation in order to change the barrier height of GaAs Schottky contacts. The dependence on the annealing temperature and implantation dose of the barrier height variation, as well as of the diode quality factor are also reported. In both cases, the observed behaviour is related to the presence of defects created by implantation in the surface layer, and their annealing kinetics.

  1. Simulation of low Schottky barrier MOSFETs using an improved Multi-subband Monte Carlo model

    Science.gov (United States)

    Gudmundsson, Valur; Palestri, Pierpaolo; Hellström, Per-Erik; Selmi, Luca; Östling, Mikael

    2013-01-01

    We present a simple and efficient approach to implement Schottky barrier contacts in a Multi-subband Monte Carlo simulator by using the subband smoothening technique to mimic tunneling at the Schottky junction. In the absence of scattering, simulation results for Schottky barrier MOSFETs are in agreement with ballistic Non-Equilibrium Green's Functions calculations. We then include the most relevant scattering mechanisms, and apply the model to the study of double gate Schottky barrier MOSFETs representative of the ITRS 2015 high performance device. Results show that a Schottky barrier height of less than approximately 0.15 eV is required to outperform the doped source/drain structure.

  2. Metal-semiconductor Schottky barrier junctions and their applications

    CERN Document Server

    1984-01-01

    The present-day semiconductor technology would be inconceivable without extensive use of Schottky barrier junctions. In spite of an excellent book by Professor E.H. Rhoderick (1978) dealing with the basic principles of metal­ semiconductor contacts and a few recent review articles, the need for a monograph on "Metal-Semiconductor Schottky Barrier Junctions and Their Applications" has long been felt by students, researchers, and technologists. It was in this context that the idea of publishing such a monograph by Mr. Ellis H. Rosenberg, Senior Editor, Plenum Publishing Corporation, was considered very timely. Due to the numerous and varied applications of Schottky barrier junctions, the task of bringing it out, however, looked difficult in the beginning. After discussions at various levels, it was deemed appropriate to include only those typical applications which were extremely rich in R&D and still posed many challenges so that it could be brought out in the stipulated time frame. Keeping in view the la...

  3. Barrier height determination in homogeneous nonideal Schottky contacts

    Science.gov (United States)

    Hernández, M. P.; Alonso, C. F.; Peña, J. L.

    2001-04-01

    A novel method is proposed to determine effective barrier heights in homogeneous nonideal Schottky contact from I-V measurements. This method takes into account the different mechanisms of current flow through the metal-semiconductor interface. The total current has been expressed as the sum of two independent terms which are: (1) the thermionic current where the ideality factor value is equal to one and (2) the contribution of different transport mechanisms. The second term responds to a general expression of the thermionic emission theory where the barrier height and the ideality factor are voltage dependent. The effective barrier height is found by means of subtraction of the transport mechanism terms from the total current. The method was applied to a group of I-V experimental curves which were reported by M Barus and D Donoval 1993 Solid State Electron. 36 969.

  4. Modeling of Schottky Barrier Diode Millimeter-Wave Multipliers at Cryogenic Temperatures

    DEFF Research Database (Denmark)

    Johansen, Tom K.; Rybalko, Oleksandr; Zhurbenko, Vitaliy

    2015-01-01

    We report on the evaluation of Schottky barrier diode GaAs multipliers at cryogenic temperatures. A GaAs Schottky barrier diode model is developed for theoretical estimation of doubler performance. The model is used to predict efficiency of doublers from room to cryogenic temperatures...

  5. Schottky Barrier CdTe(Cl) Detectors for Planetary Missions

    Science.gov (United States)

    Eisen, Yosef; Floyd, Samuel

    2002-10-01

    Schottky barrier cadmium telluride (CdTe) radiation detectors of dimensions 2mm × 2mm × 1mm and segmented monolithic 3cm × 3 cm × 1mm are under study at GSFC for future NASA planetary instruments. These instruments will perform x-ray fluorescence spectrometry of the surface and monitor the solar x-ray flux spectrum, the excitation source for the characteristic x-rays emitted from the planetary body. The Near Earth Asteroid Rendezvous (NEAR) mission is the most recent example of such a remote sensing technique. Its x-ray fluorescence detectors were gas proportional counters with a back up Si PIN solar monitor. Analysis of NEAR data has shown the necessity to develop a solar x-ray detector with efficiency extending to 30keV. Proportional counters and Si diodes have low sensitivity above 9keV. Our 2mm × 2mm × 1mm CdTe operating at -30°C possesses an energy resolution of 250eV FWHM for 55Fe with unit efficiency to up to 30keV. This is an excellent candidate for a solar monitor. Another ramification of the NEAR data is a need to develop a large area detector system, 20-30 cm2, with cosmic ray charged particle rejection, for measuring the characteristic radiation. A 3cm × 3cm × 1mm Schottky CdTe segmented monolithic detector is under investigation for this purpose. A tiling of 2-3 such detectors will result in the desired area. The favorable characteristics of Schottky CdTe detectors, the system design complexities when using CdTe and its adaptation to future missions will be discussed.

  6. Barrier inhomogeneities limited current and 1/f noise transport in GaN based nanoscale Schottky barrier diodes

    Science.gov (United States)

    Kumar, Ashutosh; Heilmann, M.; Latzel, Michael; Kapoor, Raman; Sharma, Intu; Göbelt, M.; Christiansen, Silke H.; Kumar, Vikram; Singh, Rajendra

    2016-01-01

    The electrical behaviour of Schottky barrier diodes realized on vertically standing individual GaN nanorods and array of nanorods is investigated. The Schottky diodes on individual nanorod show highest barrier height in comparison with large area diodes on nanorods array and epitaxial film which is in contrast with previously published work. The discrepancy between the electrical behaviour of nanoscale Schottky diodes and large area diodes is explained using cathodoluminescence measurements, surface potential analysis using Kelvin probe force microscopy and 1ow frequency noise measurements. The noise measurements on large area diodes on nanorods array and epitaxial film suggest the presence of barrier inhomogeneities at the metal/semiconductor interface which deviate the noise spectra from Lorentzian to 1/f type. These barrier inhomogeneities in large area diodes resulted in reduced barrier height whereas due to the limited role of barrier inhomogeneities in individual nanorod based Schottky diode, a higher barrier height is obtained. PMID:27282258

  7. Barrier inhomogeneities limited current and 1/f noise transport in GaN based nanoscale Schottky barrier diodes.

    Science.gov (United States)

    Kumar, Ashutosh; Heilmann, M; Latzel, Michael; Kapoor, Raman; Sharma, Intu; Göbelt, M; Christiansen, Silke H; Kumar, Vikram; Singh, Rajendra

    2016-01-01

    The electrical behaviour of Schottky barrier diodes realized on vertically standing individual GaN nanorods and array of nanorods is investigated. The Schottky diodes on individual nanorod show highest barrier height in comparison with large area diodes on nanorods array and epitaxial film which is in contrast with previously published work. The discrepancy between the electrical behaviour of nanoscale Schottky diodes and large area diodes is explained using cathodoluminescence measurements, surface potential analysis using Kelvin probe force microscopy and 1ow frequency noise measurements. The noise measurements on large area diodes on nanorods array and epitaxial film suggest the presence of barrier inhomogeneities at the metal/semiconductor interface which deviate the noise spectra from Lorentzian to 1/f type. These barrier inhomogeneities in large area diodes resulted in reduced barrier height whereas due to the limited role of barrier inhomogeneities in individual nanorod based Schottky diode, a higher barrier height is obtained.

  8. Additional electric field in real trench MOS barrier Schottky diode

    Science.gov (United States)

    Mamedov, R. K.; Aslanova, A. R.

    2016-04-01

    In real trench MOS barrier Schottky diode (TMBS diode) additional electric field (AEF) the whole is formed in the near contact region of the semiconductor and its propagation space is limited with the barrier metal and the metallic electrodes of MOS structures. Effective potential barrier height TMBS diode is formed via resulting electric field of superposition AEF and electric field of space charge region (SCR) semiconductor. The dependence of the resulting electric field intensity of the distance towards the inside the semiconductor is nonlinear and characterized by a peak at a certain distance from the interface. The thickness of the SCR in TMBS diode becomes equal to the trench depth. Force and energy parameters of the AEF, and thus resulting electric field in the SCR region, become dependent on the geometric design parameters TMBS diode. The forward I-V characteristic TMBS diode is described by the thermionic emission theory as in conventional flat Scottky diode, and in the reverse bias, current is virtually absent at initial voltage, appears abruptly at a certain critical voltage.

  9. Interlayer coupling effects on Schottky barrier in the arsenene-graphene van der Waals heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Congxin, E-mail: xiacongxin@htu.edu.cn; Xue, Bin; Wang, Tianxing; Peng, Yuting [Department of Physic, Henan Normal University, Xinxiang 453007 (China); Jia, Yu [School of Physics and Engineering, Zhengzhou University, Zhengzhou 450052 (China)

    2015-11-09

    The electronic characteristics of arsenene-graphene van der Waals (vdW) heterostructures are studied by using first-principles methods. The results show that a linear Dirac-like dispersion relation around the Fermi level can be quite well preserved in the vdW heterostructures. Moreover, the p-type Schottky barrier (0.18 eV) to n-type Schottky barrier (0.31 eV) transition occurs when the interlayer distance increases from 2.8 to 4.5 Å, which indicates that the Schottky barrier can be tuned effectively by the interlayer distance in the vdW heterostructures.

  10. Novel palladium germanide schottky contact for high performance schottky barrier ge MOSFETs and characterization of its leakage current mechanism.

    Science.gov (United States)

    Oh, Se-Kyung; Shin, Hong-Sik; Kang, Min-Ho; Lee, Ga-Won; Lee, Hi-Deok

    2012-07-01

    The leakage current mechanism of Palladium (Pd) germanide Schottky contact on n-type Ge-on-Si substrate is analyzed in depth. The electric field dependent analysis shows that the dominant leakage current mechanism is the Poole-Frenkel emission due to the existence of deep level traps in the depletion region of the Pd germanide/n-type Ge Schottky diode. The analysis of the dependence of leakage current on temperature also shows that the Poole-Frenkel emission and generation current are the dominant components below 100 degrees C and that the Schottky emission related to thermionic emission of majority carriers over a potential barrier is the main cause of this dominance at high temperature region.

  11. Bias stress instability involving subgap state transitions in a-IGZO Schottky barrier diodes

    Science.gov (United States)

    Qian, Huimin; Wu, Chenfei; Lu, Hai; Xu, Weizong; Zhou, Dong; Ren, Fangfang; Chen, Dunjun; Zhang, Rong; Zheng, Youdou

    2016-10-01

    Vertical Schottky barrier diodes (SBDs) based on amorphous indium-gallium-zinc-oxide (a-IGZO) with either a top or bottom Schottky contact are fabricated by controlling the oxygen partial pressure during a-IGZO deposition. Although Au electrodes are employed for both Schottky and Ohmic contacts, it is found that Schottky contacts are preferentially formed on a-IGZO film in lower oxygen vacancy concentrations. The effect of negative bias stress on device performance is studied. The Schottky barrier height and series resistance of the a-IGZO SBD are found to increase upon negative bias stress, which is correlated with a reduction of the trap state and background carrier concentration within the a-IGZO film. A physical model based on subgap state transitions from ionized V\\text{O}2+ states to neutralized V O states is proposed to explain the observed electrical instability behavior.

  12. The Effect of Bilayer Graphene Nanoribbon Geometry on Schottky-Barrier Diode Performance

    OpenAIRE

    Meisam Rahmani; Razali Ismail; Mohammad Taghi Ahmadi; Mohammad Javad Kiani; Mehdi Saeidmanesh; F. A. Hediyeh Karimi; Elnaz Akbari; Komeil Rahmani

    2013-01-01

    Bilayer graphene nanoribbon is a promising material with outstanding physical and electrical properties that offers a wide range of opportunities for advanced applications in future nanoelectronics. In this study, the application of bilayer graphene nanoribbon in schottky-barrier diode is explored due to its different stacking arrangements. In other words, bilayer graphene nanoribbon schottky-barrier diode is proposed as a result of contact between a semiconductor (AB stacking) and metal (AA ...

  13. Characteristics of Schottky Barrier Junction Based on Hexagonal Microtube ZnO

    Institute of Scientific and Technical Information of China (English)

    GAO Hui; LI Yan; YANG Li-ping; DENG Hong

    2005-01-01

    Hexagonal microtube ZnO was firstly grown on single crystal p-Si (111) substrates by hydrothermal method, and fabricated Ag/n-ZnO and Au/n-ZnO Schottky junction. Schottky effective barrier heights were calculated by I-V measurement. It is confirmed that the presence of a large amount of surface states related possibly to lattice imperfections existed near the surface leads to the pinning of the surface Fermi level at 0.35 eV below the conduction-band edge. Then the fabricated Schottky barrier junctions are evaluated for their use as UV photodetectors.

  14. Black Phosphorus Transistors with Near Band Edge Contact Schottky Barrier

    Science.gov (United States)

    Ling, Zhi-Peng; Sakar, Soumya; Mathew, Sinu; Zhu, Jun-Tao; Gopinadhan, K.; Venkatesan, T.; Ang, Kah-Wee

    2015-12-01

    Black phosphorus (BP) is a new class of 2D material which holds promise for next generation transistor applications owing to its intrinsically superior carrier mobility properties. Among other issues, achieving good ohmic contacts with low source-drain parasitic resistance in BP field-effect transistors (FET) remains a challenge. For the first time, we report a new contact technology that employs the use of high work function nickel (Ni) and thermal anneal to produce a metal alloy that effectively reduces the contact Schottky barrier height (ΦB) in a BP FET. When annealed at 300 °C, the Ni electrode was found to react with the underlying BP crystal and resulted in the formation of nickel-phosphide (Ni2P) alloy. This serves to de-pin the metal Fermi level close to the valence band edge and realizes a record low hole ΦB of merely ~12 meV. The ΦB at the valence band has also been shown to be thickness-dependent, wherein increasing BP multi-layers results in a smaller ΦB due to bandgap energy shrinkage. The integration of hafnium-dioxide high-k gate dielectric additionally enables a significantly improved subthreshold swing (SS ~ 200 mV/dec), surpassing previously reported BP FETs with conventional SiO2 gate dielectric (SS > 1 V/dec).

  15. Guard-ring termination for high-voltage SiC Schottky barrier diodes; Guard ring shutan kozo wo sonaeta kotaiatsu SiC Schottky barrier diode

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, K.; Urushidani, T.; Seki, Y. [Fuji Electric Corporate Research and Development, Ltd., Kanagawa (Japan)

    1996-03-10

    Silicon carbide (SiC) has been attracting attention as a material for power devices, and has already demonstrated its favorable characteristics in Schottky barrier diodes (SBD) with gold or platinum. However, few researchers have discussed the device terminal structures, and the authors propose a simple, efficient guard-ring terminal structure. The SBD of SiC is prepared, with Al/Ti as the Schottky metals. The Al/Ti electrode forms a Schottky barrier with the n-type drift region, and an ohmic contact with the p-type region, i.e., guard-ring region. Resistance of this structure to voltage is determined by that of the mesa section of the p-n junction, and the mesa structure is formed by selective oxidation. The SBD shows a break-down voltage of 550V, which is roughly twice as high as that of an SBD having no guard-ring structure. 7 refs., 3 figs.

  16. Tuning the Schottky barrier in the arsenene/graphene van der Waals heterostructures by electric field

    Science.gov (United States)

    Li, Wei; Wang, Tian-Xing; Dai, Xian-Qi; Wang, Xiao-Long; Ma, Ya-Qiang; Chang, Shan-Shan; Tang, Ya-Nan

    2017-04-01

    Using density functional theory calculations, we investigate the electronic properties of arsenene/graphene van der Waals (vdW) heterostructures by applying external electric field perpendicular to the layers. It is demonstrated that weak vdW interactions dominate between arsenene and graphene with their intrinsic electronic properties preserved. We find that an n-type Schottky contact is formed at the arsenene/graphene interface with a Schottky barrier of 0.54 eV. Moreover, the vertical electric field can not only control the Schottky barrier height but also the Schottky contacts (n-type and p-type) and Ohmic contacts (n-type) at the interface. Tunable p-type doping in graphene is achieved under the negative electric field because electrons can transfer from the Dirac point of graphene to the conduction band of arsenene. The present study would open a new avenue for application of ultrathin arsenene/graphene heterostructures in future nano- and optoelectronics.

  17. Annealing temperature influence on the degree of inhomogeneity of the Schottky barrier in Ti/4H—SiC contacts

    Science.gov (United States)

    Han, Lin-Chao; Shen, Hua-Jun; Liu, Ke-An; Wang, Yi-Yu; Tang, Yi-Dan; Bai, Yun; Xu, Heng-Yu; Wu, Yu-Dong; Liu, Xin-Yu

    2014-12-01

    Tung's model was used to analyze anomalies observed in Ti/SiC Schottky contacts. The degree of the inhomogeneous Schottky barrier after annealing at different temperatures is characterized by the ‘T0 anomaly’ and the difference (△Φ) between the uniformly high barrier height (ΦB0) and the effective barrier height (ΦBeff). Those two parameters of Ti Schottky contacts on 4H—SiC were deduced from I-V measurements in the temperature range of 298 K-503 K. The increase in Schottky barrier (SB) height (ΦB) and decrease in the ideality factor (n) with an increase measurement temperature indicate the presence of an inhomogeneous SB. The degree of inhomogeneity of the Schottky barrier depends on the annealing temperature, and it is at its lowest for 500-°C thermal treatment. The degree of inhomogeneity of the SB could reveal effects of thermal treatments on Schottky contacts in other aspects.

  18. Evaluation of Schottky barrier height on 4H-SiC m-face \\{ 1\\bar{1}00\\} for Schottky barrier diode wall integrated trench MOSFET

    Science.gov (United States)

    Kobayashi, Yusuke; Ishimori, Hiroshi; Kinoshita, Akimasa; Kojima, Takahito; Takei, Manabu; Kimura, Hiroshi; Harada, Shinsuke

    2017-04-01

    We proposed an Schottky barrier diode wall integrated trench MOSFET (SWITCH-MOS) for the purposes of shrinking the cell pitch and suppressing the forward degradation of the body diode. A trench Schottky barrier diode (SBD) was integrated into a trench gate MOSFET with a wide shielding p+ region that protected the trench bottoms of both the SBD and the MOS gate from high electrical fields in the off state. The SBD was placed on the trench sidewall of the \\{ 1\\bar{1}00\\} plane (m-face). Static and transient simulations revealed that SWITCH-MOS sufficiently suppressed the bipolar current that induced forward degradation, and we determined that the optimum Schottky barrier height (SBH) was from 0.8 to 2.0 eV. The SBH depends on the crystal planes in 4H-SiC, but the SBH of the m-face was unclear. We fabricated a planar m-face SBD for the first time, and we obtained SBHs from 1.4 to 1.8 eV experimentally with titanium or nickel as a Schottky metal.

  19. Transport and performance of a zero-Schottky barrier and doped contacts graphene nanoribbon transistors

    Science.gov (United States)

    Alam, Khairul

    2009-01-01

    The transport physics and performance of a top gate graphene nanoribbon (GNR) on an insulator transistor are studied for both the MOSFET like doped source-drain and the zero-Schottky barrier source-drain contacts. A voltage controlled tunnel barrier is the device transport physics. The doped source-drain contact device has a higher gate capacitance, higher transconductance, higher on/off current ratio and higher on-state current. The higher on-state current results in a lower switching delay of 17 fs, and the higher transconductance results in a higher intrinsic cut-off frequency of 27 THz in the doped source-drain contact device. The gate voltage, beyond the source-channel flat band condition, modulates both the tunnel and the thermal barrier in the doped source-drain contact devices and the tunnel barrier only in the Schottky contact devices. This limits the on-state current of Schottky contact devices.

  20. Quantum compact model for thin-body double-gate Schottky barrier MOSFETs

    Institute of Scientific and Technical Information of China (English)

    Luan Su-Zhen; Liu Hong-Xia

    2008-01-01

    Nanoscale Schottky barrier metal oxide semiconductor field-effect transistors (MOSFETs) are explored by using quantum mechanism effects for thin-body devices. The results suggest that for small nonnegative Schottky barrier heights, even for zero barrier height, the tunnelling current also plays a role in the total on-state current. Owing to the thin body of device, quantum confinement raises the electron energy levels in the silicon, and the tradeoff takes place between the quantum confinement energy and Schottky barrier lowering (SBL). It is concluded that the inclusion of the quantum mechanism effect in this model, which considers an infinite rectangular well with a first-order perturbation in the channel, can lead to the good agreement with numerical result for thin silicon film. The error increases with silicon thickness increasing.

  1. Investigation of significantly high barrier height in Cu/GaN Schottky diode

    Directory of Open Access Journals (Sweden)

    Manjari Garg

    2016-01-01

    Full Text Available Current-voltage (I-V measurements combined with analytical calculations have been used to explain mechanisms for forward-bias current flow in Copper (Cu Schottky diodes fabricated on Gallium Nitride (GaN epitaxial films. An ideality factor of 1.7 was found at room temperature (RT, which indicated deviation from thermionic emission (TE mechanism for current flow in the Schottky diode. Instead the current transport was better explained using the thermionic field-emission (TFE mechanism. A high barrier height of 1.19 eV was obtained at room temperature. X-ray photoelectron spectroscopy (XPS was used to investigate the plausible reason for observing Schottky barrier height (SBH that is significantly higher than as predicted by the Schottky-Mott model for Cu/GaN diodes. XPS measurements revealed the presence of an ultrathin cuprous oxide (Cu2O layer at the interface between Cu and GaN. With Cu2O acting as a degenerate p-type semiconductor with high work function of 5.36 eV, a high barrier height of 1.19 eV is obtained for the Cu/Cu2O/GaN Schottky diode. Moreover, the ideality factor and barrier height were found to be temperature dependent, implying spatial inhomogeneity of barrier height at the metal semiconductor interface.

  2. Investigation of significantly high barrier height in Cu/GaN Schottky diode

    Energy Technology Data Exchange (ETDEWEB)

    Garg, Manjari, E-mail: meghagarg142@gmail.com; Kumar, Ashutosh; Singh, R. [Department of Physics, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi-110016 (India); Nagarajan, S.; Sopanen, M. [Department of Micro and Nanosciences, Aalto University, P.O. Box 13500, FI-00076, Aalto (Finland)

    2016-01-15

    Current-voltage (I-V) measurements combined with analytical calculations have been used to explain mechanisms for forward-bias current flow in Copper (Cu) Schottky diodes fabricated on Gallium Nitride (GaN) epitaxial films. An ideality factor of 1.7 was found at room temperature (RT), which indicated deviation from thermionic emission (TE) mechanism for current flow in the Schottky diode. Instead the current transport was better explained using the thermionic field-emission (TFE) mechanism. A high barrier height of 1.19 eV was obtained at room temperature. X-ray photoelectron spectroscopy (XPS) was used to investigate the plausible reason for observing Schottky barrier height (SBH) that is significantly higher than as predicted by the Schottky-Mott model for Cu/GaN diodes. XPS measurements revealed the presence of an ultrathin cuprous oxide (Cu{sub 2}O) layer at the interface between Cu and GaN. With Cu{sub 2}O acting as a degenerate p-type semiconductor with high work function of 5.36 eV, a high barrier height of 1.19 eV is obtained for the Cu/Cu{sub 2}O/GaN Schottky diode. Moreover, the ideality factor and barrier height were found to be temperature dependent, implying spatial inhomogeneity of barrier height at the metal semiconductor interface.

  3. Analytical modeling of trilayer graphene nanoribbon Schottky-barrier FET for high-speed switching applications.

    Science.gov (United States)

    Rahmani, Meisam; Ahmadi, Mohammad Taghi; Abadi, Hediyeh Karimi Feiz; Saeidmanesh, Mehdi; Akbari, Elnaz; Ismail, Razali

    2013-01-30

    Recent development of trilayer graphene nanoribbon Schottky-barrier field-effect transistors (FETs) will be governed by transistor electrostatics and quantum effects that impose scaling limits like those of Si metal-oxide-semiconductor field-effect transistors. The current-voltage characteristic of a Schottky-barrier FET has been studied as a function of physical parameters such as effective mass, graphene nanoribbon length, gate insulator thickness, and electrical parameters such as Schottky barrier height and applied bias voltage. In this paper, the scaling behaviors of a Schottky-barrier FET using trilayer graphene nanoribbon are studied and analytically modeled. A novel analytical method is also presented for describing a switch in a Schottky-contact double-gate trilayer graphene nanoribbon FET. In the proposed model, different stacking arrangements of trilayer graphene nanoribbon are assumed as metal and semiconductor contacts to form a Schottky transistor. Based on this assumption, an analytical model and numerical solution of the junction current-voltage are presented in which the applied bias voltage and channel length dependence characteristics are highlighted. The model is then compared with other types of transistors. The developed model can assist in comprehending experiments involving graphene nanoribbon Schottky-barrier FETs. It is demonstrated that the proposed structure exhibits negligible short-channel effects, an improved on-current, realistic threshold voltage, and opposite subthreshold slope and meets the International Technology Roadmap for Semiconductors near-term guidelines. Finally, the results showed that there is a fast transient between on-off states. In other words, the suggested model can be used as a high-speed switch where the value of subthreshold slope is small and thus leads to less power consumption.

  4. ON current enhancement of nanowire Schottky barrier tunnel field effect transistors

    Science.gov (United States)

    Takei, Kohei; Hashimoto, Shuichiro; Sun, Jing; Zhang, Xu; Asada, Shuhei; Xu, Taiyu; Matsukawa, Takashi; Masahara, Meishoku; Watanabe, Takanobu

    2016-04-01

    Silicon nanowire Schottky barrier tunnel field effect transistors (NW-SBTFETs) are promising structures for high performance devices. In this study, we fabricated NW-SBTFETs to investigate the effect of nanowire structure on the device characteristics. The NW-SBTFETs were operated with a backgate bias, and the experimental results demonstrate that the ON current density is enhanced by narrowing the width of the nanowire. We confirmed using the Fowler-Nordheim plot that the drain current in the ON state mainly comprises the quantum tunneling component through the Schottky barrier. Comparison with a technology computer aided design (TCAD) simulation revealed that the enhancement is attributed to the electric field concentration at the corners of cross-section of the NW. The study findings suggest an effective approach to securing the ON current by Schottky barrier width modulation.

  5. Intrinsic inhomogeneity in barrier height at monolayer graphene/SiC Schottky junction

    Science.gov (United States)

    Tomer, D.; Rajput, S.; Hudy, L. J.; Li, C. H.; Li, L.

    2014-07-01

    Graphene interfaced with a semiconductor forms a Schottky junction with rectifying properties. The inherent spatial inhomogeneity due to the formation of ripples and ridges in graphene can lead to fluctuations in the Schottky barrier height (SBH). The non-ideal behavior of the temperature dependent barrier height and ideality factor greater than 4 can be attributed to these spatial inhomogeneities. Assuming a Gaussian distribution of the barrier, mean SBHs of 1.30 ± 0.18 eV and 1.16 ± 0.16 eV are found for graphene/SiC junctions on the C- and Si-face, respectively. These findings reveal intrinsic spatial inhomogeneities in the SBHs in graphene based Schottky junctions.

  6. Phase Transition Sensitive Schottky Barriers In Ga-Si(P Contacts

    Directory of Open Access Journals (Sweden)

    B.P. Modi

    2013-05-01

    Full Text Available Investigation and understanding of Schottky diodes continue to be interesting both for basic as well as technological points of view. Even now the evolutionary aspects of such contacts are not very clearly understood. In this paper it is shown that in respect of interfacial strain contribution to the barrier heights of such contacts semiconductor – liquid metal contacts are relatively better placed than solid semiconductor-solid metal contacts. Results on Ga-Si(p contact are discussed in this paper to show phase sensitive contribution to the barrier height of such Schottky contacts.

  7. An Anomalous Gain Mechanism in GaN Schottky Barrier Ultraviolet Photodetectors

    Institute of Scientific and Technical Information of China (English)

    ZHAO De-Gang; JIANG De-Sheng; LIU Zong-Shun; ZHU Jian-Jun; WANG Hui; ZHANG Shu-Ming; YANG Hui

    2009-01-01

    The gain mechanism in GaN Sehottky barrier ultraviolet photodetectors is investigated by focused light beam.When the incident light illuminates the central region of the Schottky contact electrode, the responsivity changes very little with the increase of reverse bias voltage. However, when the incident light illuminates the edge region of the electrode, the responsivity increases remarkably with the increase of reverse bias voltage, and the corresponding quantum efficiency could be even higher than 100%. It is proposed that the surface states near the edge of the electrode may lead to a reduction of effective Schottky barrier height and an enhancement of electron injection, resulting in the anomalous gain.

  8. Schottky barrier parameters and structural properties of rapidly annealed Zr Schottky electrode on p-type GaN

    Science.gov (United States)

    Rajagopal Reddy, V.; Asha, B.; Choi, Chel-Jong

    2017-06-01

    The Schottky barrier junction parameters and structural properties of Zr/p-GaN Schottky diode are explored at various annealing temperatures. Experimental analysis showed that the barrier height (BH) of the Zr/p-GaN Schottky diode increases with annealing at 400 °C (0.92 eV (I-V)/1.09 eV (C-V)) compared to the as-deposited one (0.83 eV (I-V)/0.93 eV (C-V)). However, the BH decreases after annealing at 500 °C. Also, at different annealing temperatures, the series resistance and BH are assessed by Cheung's functions and their values compared. Further, the interface state density (N SS) of the diode decreases after annealing at 400 °C and then somewhat rises upon annealing at 500 °C. Analysis reveals that the maximum BH is obtained at 400 °C, and thus the optimum annealing temperature is 400 °C for the diode. The XPS and XRD analysis revealed that the increase in BH may be attributed to the creation of Zr-N phases with increasing annealing up to 400 °C. The BH reduces for the diode annealed at 500 °C, which may be due to the formation of Ga-Zr phases at the junction. The AFM measurements reveal that the overall surface roughness of the Zr film is quite smooth during rapid annealing process. Project supported by the R&D Program for Industrial Core Technology (No. 10045216) and the Transfer Machine Specialized Lighting Core Technology Development Professional Manpower Training Project (No. N0001363) Funded by the Ministry of Trade, Industry and Energy (MOTIE), Republic of Korea.

  9. Effect of temperature and post-deposition annealing on Schottky barrier characterization of Bromoindium phthalocyanine/aluminum interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Azim-Araghi, M.E.; Sahebi, R., E-mail: ramezan.sahebi@yahoo.com

    2014-01-15

    To investigate DC electrical properties and Schottky barrier characterization between BrInPc/Al interfaces, some thin films of BrInPc in sandwich form were prepared with Al electrodes. J–V characterization showed ohmic behavior at lower voltages upto 0.3 V followed by Schottky emission conduction mechanism at higher voltages. In the Schottky region two different slopes in the plot of ln (J) against V{sup 1/2} were observed and two different values of Schottky barrier height was determined for these regions. To investigate the effect of temperature on Schottky barrier behavior between BrInPc and aluminum interface, we studied the J–V characteristics of devices at the temperature range of 298–373 K. By increasing the temperature, the width of Schottky depletion region decreased and the Schottky barrier height increased, and at temperatures higher than 333 K the dominant conduction mechanism changed to Poole–Frenkel type. For annealed samples at 373 K and 423 K, the Schottky barrier height increased as the result of thermal annealing and increasing annealing temperature. The width of the Schottky depletion region decreased by annealing and increasing the annealing temperature.

  10. Investigation on a radiation tolerant betavoltaic battery based on Schottky barrier diode

    Energy Technology Data Exchange (ETDEWEB)

    Liu Yebing [Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064 (China); Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Hu Rui; Yang Yuqing; Wang Guanquan [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Luo Shunzhong, E-mail: Luoshzh@caep.ca.cn [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Liu Ning [Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064 (China)

    2012-03-15

    An Au-Si Schottky barrier diode was studied as the energy conversion device of betavoltaic batteries. Its electrical performance under radiation of Ni-63 and H-3 sources and radiation degradation under Am-241 were investigated and compared with those of the p-n junction. The results show that the Schottky diode had a higher I{sub sc} and harder radiation tolerance but lower V{sub oc} than the p-n junction. The results indicated that the Schottky diode can be a promising candidate for energy conversion of betavoltaic batteries. - Highlights: Black-Right-Pointing-Pointer The Schottky diode was used as the converter of the betavoltaic battery. Black-Right-Pointing-Pointer The radiation damage of converter was accelerated by using alpha particles. Black-Right-Pointing-Pointer The Schottky diode has higher radiation resistance than that of the p-n junction. Black-Right-Pointing-Pointer The Schottky diode could still be a promising converter of the betavoltaic battery.

  11. Investigation of Thickness Dependence of Metal Layer in Al/Mo/4H-SiC Schottky Barrier Diodes.

    Science.gov (United States)

    Lee, Seula; Lee, Jinseon; Kang, Tai-Young; Kyoung, Sinsu; Jung, Eun Sik; Kim, Kyung Hwan

    2015-11-01

    In this paper, we present the preparation and characterization of Schottky barrier diodes based on silicon carbide with various Schottky metal layer thickness values. In this structure, molybdenum and aluminum were employed as the Schottky barrier metal and top electrode, respectively. Schottky metal layers were deposited with thicknesses ranging from 1000 to 3000 Å, and top electrodes were deposited with thickness as much as 3000 Å. The deposition of both metal layers was performed using the facing target sputtering (FTS) method, and the fabricated samples were annealed with the tubular furnace at 300 degrees C under argon ambient for 10 min. The Schottky barrier height, series resistance, and ideality factor was calculated from the forward I-V characteristic curve using the methods proposed by Cheung and Cheung, and by Norde. For as-deposited Schottky diodes, we observed an increase of the threshold voltage (V(T)) as the thickness of the Schottky metal layer increased. After the annealing, the Schottky barrier heights (SBHs) of the diodes, including Schottky metal layers of over 2000 Å, increased. In the case of the Schottky metal layer deposited to 1000 Å, the barrier heights decreased due to the annealing process. This may have been caused by the interfacial penetration phenomenon through the Schottky metal layer. For variations of V(T), the SBH changed with a similar tendency. The ideality factor and series resistance showed no significant changes before or after annealing. This indicates that this annealing condition is appropriate for Mo SiC structures. Our results confirm that it is possible to control V(T) by adjusting the thickness of the Schottky metal layer.

  12. INTERFACE STRUCTURE AND SCHOTTKY BARRIERS AT EPITAXIAL SI(111)/PB INTERFACES

    NARCIS (Netherlands)

    WEITERING, HH; HIBMA, T; HESLINGA, DR; KLAPWIJK, TM

    1991-01-01

    Two different epitaxial Si(111)/Pb interfaces can be prepared, i.e. a metastable interface with a (7 x 7) and a stable interface with an incommensurate but close to (square-root 3 x square-root 3)R30-degrees surface unit cell. Schottky barrier heights of diodes made by depositing thick Pb layers on

  13. Summary of Schottky barrier height data on epitaxially grown n-and p-GaAs

    CSIR Research Space (South Africa)

    Myburg, G

    1998-07-18

    Full Text Available epitaxially (OMVPE) grown (100) n-type GaAs material and 13 metals on molecular beam epitaxially grown (MBE) p-GaAs, are presented. Of all the metals involved in this study, Ga had the lowest mean Schottky barrier height of about 0.60 eV on n-GaAs...

  14. Charge transport mechanisms of graphene/semiconductor Schottky barriers: A theoretical and experimental study

    Science.gov (United States)

    Zhong, Haijian; Xu, Ke; Liu, Zhenghui; Xu, Gengzhao; Shi, Lin; Fan, Yingmin; Wang, Jianfeng; Ren, Guoqiang; Yang, Hui

    2014-01-01

    Graphene has been proposed as a material for semiconductor electronic and optoelectronic devices. Understanding the charge transport mechanisms of graphene/semiconductor Schottky barriers will be crucial for future applications. Here, we report a theoretical model to describe the transport mechanisms at the interface of graphene and semiconductors based on conventional semiconductor Schottky theory and a floating Fermi level of graphene. The contact barrier heights can be estimated through this model and be close to the values obtained from the experiments, which are lower than those of the metal/semiconductor contacts. A detailed analysis reveals that the barrier heights are as the function of the interface separations and dielectric constants, and are influenced by the interfacial states of semiconductors. Our calculations show how this behavior of lowering barrier heights arises from the Fermi level shift of graphene induced by the charge transfer owing to the unique linear electronic structure.

  15. Charge transport mechanisms of graphene/semiconductor Schottky barriers: A theoretical and experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Haijian; Liu, Zhenghui; Xu, Gengzhao; Shi, Lin; Fan, Yingmin; Yang, Hui [Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); Xu, Ke, E-mail: kxu2006@sinano.ac.cn; Wang, Jianfeng; Ren, Guoqiang [Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); Suzhou Nanowin Science and Technology Co., Ltd., Suzhou 215123 (China)

    2014-01-07

    Graphene has been proposed as a material for semiconductor electronic and optoelectronic devices. Understanding the charge transport mechanisms of graphene/semiconductor Schottky barriers will be crucial for future applications. Here, we report a theoretical model to describe the transport mechanisms at the interface of graphene and semiconductors based on conventional semiconductor Schottky theory and a floating Fermi level of graphene. The contact barrier heights can be estimated through this model and be close to the values obtained from the experiments, which are lower than those of the metal/semiconductor contacts. A detailed analysis reveals that the barrier heights are as the function of the interface separations and dielectric constants, and are influenced by the interfacial states of semiconductors. Our calculations show how this behavior of lowering barrier heights arises from the Fermi level shift of graphene induced by the charge transfer owing to the unique linear electronic structure.

  16. Tuning of Schottky barrier height of Al/n-Si by electron beam irradiation

    Science.gov (United States)

    Vali, Indudhar Panduranga; Shetty, Pramoda Kumara; Mahesha, M. G.; Petwal, V. C.; Dwivedi, Jishnu; Choudhary, R. J.

    2017-06-01

    The effect of electron beam irradiation (EBI) on Al/n-Si Schottky diode has been studied by I-V characterization at room temperature. The behavior of the metal-semiconductor (MS) interface is analyzed by means of variations in the MS contact parameters such as, Schottky barrier height (ΦB), ideality factor (n) and series resistance (Rs). These parameters were found to depend on the EBI dose having a fixed incident beam of energy 7.5 MeV. At different doses (500, 1000, 1500 kGy) of EBI, the Schottky contacts were prepared and extracted their contact parameters by applying thermionic emission and Cheung models. Remarkably, the tuning of ΦB was observed as a function of EBI dose. The improved n with increased ΦB is seen for all the EBI doses. As a consequence of which the thermionic emission is more favored. However, the competing transport mechanisms such as space charge limited emission, tunneling and tunneling through the trap states were ascribed due to n > 1. The analysis of XPS spectra have shown the presence of native oxide and increased radiation induced defect states. The thickness variation in the MS interface contributing to Schottky contact behavior is discussed. This study explains a new technique to tune Schottky contact parameters by metal deposition on the electron beam irradiated n-Si wafers.

  17. Tandem-structured, hot electron based photovoltaic cell with double Schottky barriers.

    Science.gov (United States)

    Lee, Young Keun; Lee, Hyosun; Park, Jeong Young

    2014-04-03

    We demonstrate a tandem-structured, hot electron based photovoltaic cell with double Schottky barriers. The tandem-structured, hot electron based photovoltaic cell is composed of two metal/semiconductor interfaces. Two types of tandem cells were fabricated using TiO2/Au/Si and TiO2/Au/TiO2, and photocurrent enhancement was detected. The double Schottky barriers lead to an additional pathway for harvesting hot electrons, which is enhanced through multiple reflections between the two barriers with different energy ranges. In addition, light absorption is improved by the band-to-band excitation of both semiconductors with different band gaps. Short-circuit current and energy conversion efficiency of the tandem-structured TiO2/Au/Si increased by 86% and 70%, respectively, compared with Au/Si metal/semiconductor nanodiodes, showing an overall solar energy conversion efficiency of 5.3%.

  18. New GaN Schottky barrier diode employing a trench on AlGaN/GaN heterostructure

    Science.gov (United States)

    Ha, Min-Woo; Lee, Seung-Chul; Choi, Young-Hwan; Kim, Soo-Seong; Yun, Chong-Man; Han, Min-Koo

    2006-10-01

    A new GaN Schottky barrier diode employing a trench structure, which is proposed and fabricated, successfully decreases a forward voltage drop without sacrificing any other electric characteristics. The trench is located in the middle of Schottky contact during a mesa etch. The Schottky metal of Pt/Mo/Ti/Au is e-gun evaporated on the 300 nm-deep trench as well as the surface of the proposed GaN Schottky barrier diode. The trench forms the vertical Au Schottky contact and lateral Pt Schottky contact due to the evaporation sequence of Schottky metal. The forward voltage drops of the proposed diode and conventional one are 0.73 V and 1.25 V respectively because the metal work function (5.15 eV) of the vertical Au Schottky contact is considerably less than that of the lateral Pt Schottky contact (5.65 eV). The proposed diode exhibits the low on-resistance of 1.58 mΩ cm 2 while the conventional one exhibits 8.20 mΩ cm 2 due to the decrease of a forward voltage drop.

  19. The Effect of Bilayer Graphene Nanoribbon Geometry on Schottky-Barrier Diode Performance

    Directory of Open Access Journals (Sweden)

    Meisam Rahmani

    2013-01-01

    Full Text Available Bilayer graphene nanoribbon is a promising material with outstanding physical and electrical properties that offers a wide range of opportunities for advanced applications in future nanoelectronics. In this study, the application of bilayer graphene nanoribbon in schottky-barrier diode is explored due to its different stacking arrangements. In other words, bilayer graphene nanoribbon schottky-barrier diode is proposed as a result of contact between a semiconductor (AB stacking and metal (AA stacking layers. To this end, an analytical model joint with numerical solution of carrier concentration for bilayer graphene nanoribbon in the degenerate and nondegenerate regimes is presented. Moreover, to determine the proposed diode performance, the carrier concentration model is adopted to derive the current-voltage characteristic of the device. The simulated results indicate a strong bilayer graphene nanoribbon geometry and temperature dependence of current-voltage characteristic showing that the forward current of the diode rises by increasing of width. In addition, the lower value of turn-on voltage appears as the more temperature increases. Finally, comparative study indicates that the proposed diode has a better performance compared to the silicon schottky diode, graphene nanoribbon homo-junction contact, and graphene-silicon schottky diode in terms of electrical parameters such as turn-on voltage and forward current.

  20. Multiple Schottky Barrier-Limited Field-Effect Transistors on a Single Si Nanowire with an Intrinsic Doping Gradient.

    Science.gov (United States)

    Barreda, Jorge L; Keiper, Timothy D; Zhang, Mei; Xiong, Peng

    2017-03-09

    In comparison to conventional (channel-limited) field-effect transistors (FETs), Schottky barrier-limited FETs possess some unique characteristics which make them attractive candidates for some electronic and sensing applications. Consequently, modulation of the nano Schottky barrier at a metal-semiconductor interface promises higher performance for chemical and biomolecular sensor applications when compared to conventional FETs with Ohmic contacts. However, the fabrication and optimization of devices with a combination of ideal Ohmic and Schottky contacts as the source and drain respectively present many challenges. We address this issue by utilizing Si nanowires (NWs) synthesized by a chemical vapor deposition process which yields a pronounced doping gradient along the length of the NWs. Devices with a series of metal contacts on a single Si NW are fabricated in a single lithography and metallization process. The graded doping profile of the NW is manifested in monotonic increases in the channel and junction resistances and variation of the nature of the contacts from Ohmic to Schottky of increasing effective barrier height along the NW. Hence multiple single Schottky junction-limited FETs with extreme asymmetry and high reproducibility are obtained on an individual NW. A definitive correlation between increasing Schottky-barrier height and enhanced gate modulation is revealed. Having access to systematically varying Schottky barrier contacts on the same NW device provides an ideal platform for identifying optimal device characteristics for sensing and electronic applications.

  1. Optimized design of 4H-SiC floating junction power Schottky barrier diodes

    Institute of Scientific and Technical Information of China (English)

    Pu Hongbin; Cao Lin; Chen Zhiming; Ren Jie

    2009-01-01

    SiC floating junction Schottky barrier diodes were simulated with software MEDICI 4.0 and their device structures were optimized based on forward and reverse electrical characteristics.Compared with the conventional power Schottky barrier diode,the device structure is featured by a highly doped drift region and embedded floating junction region,which can ensure high breakdown voltage while keeping lower specific on-state resistance,solved the contradiction between forward voltage drop and breakdown voltage.The simulation results show that with optimized structure parameter,the breakdown voltage Can reach 4 kV and the specific on-resistance is 8.3 mΩ·cm2.

  2. Schottky barriers at metal-finite semiconducting carbon nanotube interfaces

    OpenAIRE

    Xue, Yongqiang; Ratner, Mark A.

    2003-01-01

    Electronic properties of metal-finite semiconducting carbon nanotube interfaces are studied as a function of the nanotube length using a self-consistent tight-binding theory. We find that the shape of the potential barrier depends on the long-range tail of the charge transfer, leading to an injection barrier thickness comparable to half of the nanotube length until the nanotube reaches the bulk limit. The conductance of the nanotube junction shows a transition from tunneling to thermally-acti...

  3. Electrical degradation of double-Schottky barrier in ZnO varistors

    Energy Technology Data Exchange (ETDEWEB)

    He, Jinliang, E-mail: hejl@tsinghua.edu.cn; Cheng, Chenlu; Hu, Jun [The State Key Lab of Power System, Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China)

    2016-03-15

    Researches on electrical degradation of double-Schottky barrier in ZnO varistors are reviewed, aimed at the constitution of a full picture of universal degradation mechanism within the perspective of defect. Recent advances in study of ZnO materials by atomic-scale first-principles calculations are partly included and discussed, which brings to our attention distinct cognition on the native point defects and their profound impact on degradation.

  4. Planar Schottky barrier mixer diodes for space applications at submillimeter wavelengths

    Science.gov (United States)

    Bishop, W. L.; Crowe, T. W.; Mattauch, R. J.; Ostdiek, P. H.

    1991-01-01

    Available planar diodes for space-based applications at submillimeter wavelengths have not achieved either the required low junction capacitance or the low series resistance-junction capacitance product. Here, the development of a novel planar diode structure that overcomes both of these difficulties is outlined. The characteristics of these Schottky barrier mixer diodes are presented and electron micrographs are shown. The diode structure will allow planar technology to be extended throughout the submillimeter wavelength range.

  5. Tunable Schottky barrier and high responsivity in graphene/Si-nanotip optoelectronic device

    Science.gov (United States)

    Di Bartolomeo, Antonio; Giubileo, Filippo; Luongo, Giuseppe; Iemmo, Laura; Martucciello, Nadia; Niu, Gang; Fraschke, Mirko; Skibitzki, Oliver; Schroeder, Thomas; Lupina, Grzegorz

    2017-03-01

    We demonstrate tunable Schottky barrier height and record photo-responsivity in a new-concept device made of a single-layer CVD graphene transferred onto a matrix of nanotips patterned on n-type Si wafer. The original layout, where nano-sized graphene/Si heterojunctions alternate to graphene areas exposed to the electric field of the Si substrate, which acts both as diode cathode and transistor gate, results in a two-terminal barristor with single-bias control of the Schottky barrier. The nanotip patterning favors light absorption, and the enhancement of the electric field at the tip apex improves photo-charge separation and enables internal gain by impact ionization. These features render the device a photodetector with responsivity (3 {{A}} {{{W}}}-1 for white LED light at 3 {{mW}} {{{cm}}}-2 intensity) almost an order of magnitude higher than commercial photodiodes. We extensively characterize the voltage and the temperature dependence of the device parameters, and prove that the multi-junction approach does not add extra-inhomogeneity to the Schottky barrier height distribution. We also introduce a new phenomenological graphene/semiconductor diode equation, which well describes the experimental I-V characteristics both in forward and reverse bias.

  6. Determination of the Schottky barrier height of ferromagnetic contacts to few-layer phosphorene

    Energy Technology Data Exchange (ETDEWEB)

    Anugrah, Yoska; Robbins, Matthew C.; Koester, Steven J. [Department of Electrical and Computer Engineering, University of Minnesota-Twin Cities, Minneapolis, Minnesota 55455 (United States); Crowell, Paul A. [School of Physics and Astronomy, University of Minnesota-Twin Cities, Minneapolis, Minnesota 55455 (United States)

    2015-03-09

    Phosphorene, the 2D analogue of black phosphorus, is a promising material for studying spin transport due to its low spin-orbit coupling and its ½ nuclear spin, which could allow the study of hyperfine effects. In this work, the properties of permalloy (Py) and cobalt (Co) contacts to few-layer phosphorene are presented. The Schottky barrier height was extracted and determined as a function of gate bias. Flat-band barrier heights, relative to the valence band edge, of 110 meV and 200 meV were determined for Py and Co, respectively. These results are important for future studies of spin transport in phosphorene.

  7. Schottky Barrier Height Tuning via the Dopant Segregation Technique through Low-Temperature Microwave Annealing

    Directory of Open Access Journals (Sweden)

    Chaochao Fu

    2016-04-01

    Full Text Available The Schottky junction source/drain structure has great potential to replace the traditional p/n junction source/drain structure of the future ultra-scaled metal-oxide-semiconductor field effect transistors (MOSFETs, as it can form ultimately shallow junctions. However, the effective Schottky barrier height (SBH of the Schottky junction needs to be tuned to be lower than 100 meV in order to obtain a high driving current. In this paper, microwave annealing is employed to modify the effective SBH of NiSi on Si via boron or arsenic dopant segregation. The barrier height decreased from 0.4–0.7 eV to 0.2–0.1 eV for both conduction polarities by annealing below 400 °C. Compared with the required temperature in traditional rapid thermal annealing, the temperature demanded in microwave annealing is ~60 °C lower, and the mechanisms of this observation are briefly discussed. Microwave annealing is hence of high interest to future semiconductor processing owing to its unique capability of forming the metal/semiconductor contact at a remarkably lower temperature.

  8. Fabrication of 4H-SiC Schottky barrier diodes with high breakdown voltages

    CERN Document Server

    Kum, B H; Shin, M W; Park, J D

    1999-01-01

    This paper discusses the fabrication and the breakdown characteristics of 4H-SiC Schottky barrier diodes (SBDs). Optimal processing conditions for the ohmic contacts were extracted using the transmission-line method (TLM) and were applied to the device fabrication. The Ti/4H-SiC SBDs with Si sub x B sub y passivation showed a maximum reverse breakdown voltage of 268 V with a forward current density as high as 70 mA/cm sup 2 at a forward voltage of 2 V. The breakdown of the Pt. 4H-SiC SBDs without any passivation occurred at near 110 V. It is concluded that the breakdown enhancement in the Ti/4H-SiC SBDs can be attributed to the passivation; otherwise, excess surface charge near the edge of the Schottky contact would lead to electric fields of sufficient magnitude to cause field emission.

  9. Fabrication and characteristics of a 4H-SiC junction barrier Schottky diode*

    Institute of Scientific and Technical Information of China (English)

    Chen Fengping; Zhang Yuming; Lü Hongliang; Zhang Yimen; Guo Hui; Guo Xin

    2011-01-01

    4H-SiC junction barrier Schottky (JBS) diodes with four kinds of design have been fabricated and characterized using two different processes in which one is fabricated by making the P-type ohmic contact of the anode independently, and the other is processed by depositing a Schottky metal multi-layer on the whole anode. The reverse performances are compared to find the influences of these factors. The results show that JBS diodes with field guard rings have a lower reverse current density and a higher breakdown voltage, and with independent Ptype ohmic contact manufacturing, the reverse performance of 4H-SiC JBS diodes can be improved effectively.Furthermore, the P-type ohmic contact is studied in this work.

  10. Fabrication and characteristics of a 4H-SiC junction barrier Schottky diode

    Energy Technology Data Exchange (ETDEWEB)

    Chen Fengping; Zhang Yuming; Lue Hongliang; Zhang Yimen; Guo Hui; Guo Xin, E-mail: fpchen@yeah.net [School of Microelectronics, Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xidian University, Xi' an 710071 (China)

    2011-06-15

    4H-SiC junction barrier Schottky (JBS) diodes with four kinds of design have been fabricated and characterized using two different processes in which one is fabricated by making the P-type ohmic contact of the anode independently, and the other is processed by depositing a Schottky metal multi-layer on the whole anode. The reverse performances are compared to find the influences of these factors. The results show that JBS diodes with field guard rings have a lower reverse current density and a higher breakdown voltage, and with independent P-type ohmic contact manufacturing, the reverse performance of 4H-SiC JBS diodes can be improved effectively. Furthermore, the P-type ohmic contact is studied in this work. (semiconductor devices)

  11. Demonstration of a 4H SiC Betavoltaic Nuclear Battery Based on Schottky Barrier Diode

    Institute of Scientific and Technical Information of China (English)

    QIAO Da-Yong; YUAN Wei-Zheng; GAO Peng; YAO Xian-Wang; ZANG Bo; ZHANG Lin; GUO Hui; ZHANG Hong-Jian

    2008-01-01

    A 4H SiC betavoltaic nuclear battery is demonstrated. A Schottky barrier diode is utilized for carrier separation.Under illumination of Ni-63 source with an apparent activity of 4mCi/cm2, an open circuit voltage of 0.49 V and a short circuit current density of 29.44 nA/cm2 are measured. A power conversion effciency of 1.2% is obtained.The performance of the device is limited by low shunt resistance, backscattering and attenuation of electron energy in air and Schottky electrode. It is expected to be significantly improved by optimizing the design and processing technology of the device.

  12. Characterization of deep electron traps in 4H-SiC Junction Barrier Schottky rectifiers

    Science.gov (United States)

    Gelczuk, Ł.; Dąbrowska-Szata, M.; Sochacki, M.; Szmidt, J.

    2014-04-01

    Conventional deep level transient spectroscopy (DLTS) technique was used to study deep electron traps in 4H-SiC Junction Barrier Schottky (JBS) rectifiers. 4H-SiC epitaxial layers, doped with nitrogen and grown on standard n+-4H-SiC substrates were exposed to low-dose aluminum ion implantation process under the Schottky contact in order to form both JBS grid and junction termination extension (JTE), and assure good rectifying properties of the diodes. Several deep electron traps were revealed and attributed to impurities or intrinsic defects in 4H-SiC epitaxial layers, on the basis of comparison of their electrical parameters (i.e. activation energies, apparent capture cross sections and concentrations) with previously published results.

  13. Long-wavelength PtSi infrared detectors fabricated by incorporating a p(+) doping spike grown by molecular beam epitaxy

    Science.gov (United States)

    Lin, T. L.; Park, J. S.; George, T.; Jones, E. W.; Fathauer, R. W.; Maserjian, J.

    1993-01-01

    By incorporating a 1-nm-thick p(+) doping spike at the PtSi/Si interface, we have successfully demonstrated extended cutoff wavelengths of PtSi Schottky infrared detectors in the long wavelength infrared (LWIR) regime for the first time. The extended cutoff wavelengths resulted from the combined effects of an increased electric field near the silicide/Si interface due to the p(+) doping spike and the Schottky image force. The p(+) doping spikes were grown by molecular beam epitaxy at 450 C, using elemental boron as the dopant source, with doping concentrations ranging from 5 x 10 exp 19 to 2 x 10 exp 20/cu cm. Transmission electron microscopy indicated good crystalline quality of the doping spikes. The cutoff wavelengths were shown to increase with increasing doping concentrations of the p(+) spikes. Thermionic emission dark current characteristics were observed and photoresponses in the LWIR regime were demonstrated.

  14. Understanding Pt-ZnO:In Schottky nanocontacts by conductive atomic force microscopy

    Science.gov (United States)

    Chirakkara, Saraswathi; Choudhury, Palash Roy; Nanda, K. K.; Krupanidhi, S. B.

    2016-04-01

    Undoped and In doped ZnO (IZO) thin films are grown on Pt coated silicon substrates Pt/Si by pulsed laser deposition to fabricate Pt/ZnO:In Schottky diodes. The Schottky diodes were investigated by conventional two-probe current-voltage (I-V) measurements and by the I-V spectroscopy tool of conductive atomic force microscopy (C-AFM). The large deviation of the ideality factor from unity and the temperature dependent Schottky barrier heights (SBHs) obtained from the conventional method imply the presence of inhomogeneous interfaces. The inhomogeneity of SBHs is confirmed by C-AFM. Interestingly, the I-V curves at different points are found to be different, and the SBHs deduced from the point diodes reveal inhomogeneity at the nanoscale at the metal-semiconductor interface. A reduction in SBH and turn-on voltage along with enhancement in forward current are observed with increasing indium concentration.

  15. Tuning the tunneling probability by mechanical stress in Schottky barrier based reconfigurable nanowire transistors

    Science.gov (United States)

    Baldauf, Tim; Heinzig, André; Trommer, Jens; Mikolajick, Thomas; Weber, Walter Michael

    2017-02-01

    Mechanical stress is an established and important tool of the semiconductor industry to improve the performance of modern transistors. It is well understood for the enhancement of carrier mobility but rather unexplored for the control of the tunneling probability for injection dominated research devices based on tunneling phenomena, such as tunnel FETs, resonant tunnel FETs and reconfigurable Schottky FETs. In this work, the effect of stress on the tunneling probability and overall transistor characteristics is studied by three-dimensional device simulations in the example of reconfigurable silicon nanowire Schottky barrier transistors using two independently gated Schottky junctions. To this end, four different stress sources are investigated. The effects of mechanical stress on the average effective tunneling mass and on the multi-valley band structure applying the deformation potential theory are being considered. The transfer characteristics of strained transistors in n- and p-configuration and corresponding charge carrier tunneling are analyzed with respect to the current ratio between electron and hole conduction. For the implementation of these devices into complementary circuits, the mandatory current ratio of unity can be achieved by appropriate mechanical stress either by nanowire oxidation or the application of a stressed top layer.

  16. Barrier height enhancement of InP-based n-Ga(0.47)In(0.53)As Schottky-barrier diodes grown by molecular beam epitaxy

    Science.gov (United States)

    Kim, J. H.; Li, S. S.; Figueroa, L.

    1988-01-01

    Barrier height enhancement of an InP-based p(+)n-Ga(0.47)In(0.53)As Schottky diode grown by MBE has been demonstrated for infra-red photodetector applications. A barrier height of 0.35 eV for n-Ga(0.47)In(0.53)As Schottky barrier diodes, was increased to the effective barrier height of 0.55 eV, with a p(+)-Ga(0.47)In(0.53)As surface layer of 30 nm thick. The results show a reverse leakage current density of 0.0015 A/sq cm and a junction capacitance of 0.3 pF, which are comparable to those of p-Ga(0.47)In(0.53)As Schottky-barrier diodes at a reverse bias voltage of 5 V.

  17. Subthreshold Schottky-barrier thin-film transistors with ultralow power and high intrinsic gain

    Science.gov (United States)

    Lee, Sungsik; Nathan, Arokia

    2016-10-01

    The quest for low power becomes highly compelling in newly emerging application areas related to wearable devices in the Internet of Things. Here, we report on a Schottky-barrier indium-gallium-zinc-oxide thin-film transistor operating in the deep subthreshold regime (i.e., near the OFF state) at low supply voltages (400) that was both bias and geometry independent. The transistor reported here is useful for sensor interface circuits in wearable devices where high current sensitivity and ultralow power are vital for battery-less operation.

  18. Double ferromagnetic metal/semiconductor schottky barrier confined quasi-ballistic transport channel as spin polarizer

    Institute of Scientific and Technical Information of China (English)

    Wen Wu

    2007-01-01

    Spin polarizer is one of the most important devices for the newly developing field of spintronics, which may revolute the popular information techniques. Here we present a phenomenal model for a novel spin polarizer, which utilizes two back to back ferromagnetic metal/semiconductor Schottky barriers to define a semiconductor transport channel whose length is less than the spin decoherence length of the host semiconductor. Along this channel, conducting electrons move diffusively in momentum space while they keep ballistic motion in spin space. Across the channel, electrons suffer a spin dependent tunneling, which establishes spin polarization along the channel.

  19. Schottky barrier enhancement on n-InP solar cell applications

    DEFF Research Database (Denmark)

    Clausen, Thomas; Leistiko, Otto

    1994-01-01

    It is demonstrated that the Schottky barrier height on n-type InP can be enhanced to values close to the energy bandgap (1.35 eV) by employing a AuZnCr metallization. The process is simple and requires only mild and fast annealing sequences with temperatures not exceeding 500°C. Also, no critical...... epitaxial growth step of junctions is needed, making the process fairly cheap. Thus, prospects for an efficient and simple solar cell device structure for space application purposes based on highly radiant-resistant InP are greatly improved...

  20. Tuning the Schottky Barrier at the Graphene/MoS2 Interface by Electron Doping

    DEFF Research Database (Denmark)

    Jin, Chengjun; Rasmussen, Filip Anselm; Thygesen, Kristian Sommer

    2015-01-01

    Using ab initio calculations we investigate the energy level alignment at the graphene/MoS2 heterostructure and the use of electron doping as a strategy to lower the Schottky barrier and achieve a low-resistance Ohmic contact. For the neutral heterostructure, density functional theory (DFT...... layer. In contrast to the case of metal substrates, where the band alignment is governed by Pauli repulsion-induced interface dipoles, the graphene/MoS2 heterostructure shows only a negligible interface dipole. As a consequence, the band alignment at the neutral heterostructure is not changed when...... concentration is shown to be mainly governed by the electrostatic potential resulting from the doping charge....

  1. Schottky barrier height in metal-SiC contact - new approach to modelling

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, P.A.; Ignat`ev, K.I. [Ioffe Physico-Technical Inst., St. Petersburg (Russian Federation)

    1998-08-01

    A new approach to calculate Schottky barrier height in a metal-SiC contact is proposed proceeding from uniform spatial distribution of electron traps within metal-to-SiC gap represented by native oxide. The model explains well experimental data on metal-6H-SiC contacts, with comparatively low mid-gap surface state density. This is in contrast with widely used analytical model by Cowley and Sze providing high interface state density at the 6H-SiC mid-gap. (orig.) 5 refs.

  2. Anomalous forward I-V characteristics of Ti/Au SiC Schottky barrier diodes

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, D.J.; Wright, N.G.; Johnson, C.M.; O' Neill, A.G. [Newcastle upon Tyne Univ. (UK). Dept. of Electr. and Electron. Eng.; Hilton, K.P.; Uren, M.J. [Defence Evaluation Research Agency, Malvern, Worcestershire (United Kingdom)

    1999-07-30

    The aim of this study was to improve the adhesion of Au Schottky contacts to SiC. In order to do this, before the deposition of the Au layer, a thin layer of Ti was deposited. However, this resulted in an anomalous step in the forward bias electrical characteristic for some diodes. An equivalent circuit model is introduced to explain this irregularity in terms of two barrier heights. PSPICE is used to simulate this model. Simulated and experimental data are in good agreement over the temperature range 25 to 250 C. (orig.)

  3. Application of well characterized e - beam evaporated WSe2 thin films in Schottky Barrier diodes

    Science.gov (United States)

    Patel, Mayurkumar M.

    The studies of semiconductor thin films and their junctions such as metal semiconductor junctions (Schottky Barriers) have received much attention due to their applications in various electronic and optoelectronic devices including high frequency switching device, Schottky barrier devices, solar cells etc. But, realization of any electronic device using a combination of bulk and thin film or all bulk or all thin film components essentially requires metallization of metal contacts for electrical signals to flow into and out of the device. Thus junction between two metals and metal-semiconductor is an integral part of the device without which communication to the external circuit components would not be possible. In this reference stable metalsemiconductor contacts of ohmic as well as rectifying nature are very much important from technological point of view. In both cases preparation of reliable and efficient metal contacts with high yield and stability is challenging task for devices operating at high frequencies when packing density is increased by many fold. Thus, the behavior of metal-semiconductor contacts at microscopic scale may be explored for the development of future technology. The subject matter of such contacts is well documented in many books with review of developments in the recent past. Earlier devices were prepared on the bulk elemental semiconductors as an active region which was then followed by crystalline/amorphous compound semiconductors in bulk as well as thin film forms like Solar cells, p-n junction diodes, Schottky barrier devices etc. in recent past. Normally bulk crystalline'or amorphous substrate is used to support device structure made from crystalline/amorphous bulk and thin film. However, to the best of author's knowledge no attempts have been made to study the devices prepared by depositing semiconductor thin film with thin metal film supported by a by a non-conducting glass substrate. For this purpose, studies were carried out on

  4. Annealing dependence of diamond-metal Schottky barrier heights probed by hard x-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gaowei, M.; Muller, E. M. [Department of Materials Science and Engineering, SUNY Stony Brook, Stony Brook, New York 11794 (United States); Rumaiz, A. K. [National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973 (United States); Weiland, C.; Cockayne, E.; Woicik, J. C. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Jordan-Sweet, J. [IBM T.J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Smedley, J. [Instrumentation Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

    2012-05-14

    Hard x-ray photoelectron spectroscopy was applied to investigate the diamond-metal Schottky barrier heights for several metals and diamond surface terminations. The position of the diamond valence-band maximum was determined by theoretically calculating the diamond density of states and applying cross section corrections. The diamond-platinum Schottky barrier height was lowered by 0.2 eV after thermal annealing, indicating annealing may increase carrier injection in diamond devices leading to photoconductive gain. The platinum contacts on oxygen-terminated diamond was found to provide a higher Schottky barrier and therefore a better blocking contact than that of the silver contact in diamond-based electronic devices.

  5. 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.

  6. Enhanced Thermionic Emission and Low 1/f Noise in Exfoliated Graphene/GaN Schottky Barrier Diode.

    Science.gov (United States)

    Kumar, Ashutosh; Kashid, Ranjit; Ghosh, Arindam; Kumar, Vikram; Singh, Rajendra

    2016-03-01

    Temperature-dependent electrical transport characteristics of exfoliated graphene/GaN Schottky diodes are investigated and compared with conventional Ni/GaN Schottky diodes. The ideality factor of graphene/GaN and Ni/GaN diodes are measured to be 1.33 and 1.51, respectively, which is suggestive of comparatively higher thermionic emission current in graphene/GaN diode. The barrier height values for graphene/GaN diode obtained using thermionic emission model and Richardson plots are found to be 0.60 and 0.72 eV, respectively, which are higher than predicted barrier height ∼0.40 eV as per the Schottky-Mott model. The higher barrier height is attributed to hole doping of graphene due to graphene-Au interaction which shifts the Fermi level in graphene by ∼0.3 eV. The magnitude of flicker noise of graphene/GaN Schottky diode increases up to 175 K followed by its decrease at higher temperatures. This indicates that diffusion currents and barrier inhomogeneities dominate the electronic transport at lower and higher temperatures, respectively. The exfoliated graphene/GaN diode is found to have lower level of barrier inhomogeneities than conventional Ni/GaN diode, as well as earlier reported graphene/GaN diode fabricated using chemical vapor deposited graphene. The lesser barrier inhomogeneities in graphene/GaN diode results in lower flicker noise by 2 orders of magnitude as compared to Ni/GaN diode. Enhanced thermionic emission current, lower level of inhomogeneities, and reduced flicker noise suggests that graphene-GaN Schottky diodes may have the underlying trend for replacing metal-GaN Schottky diodes.

  7. A planar Al-Si Schottky barrier metal–oxide–semiconductor field effect transistor operated at cryogenic temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Purches, W. E. [School of Physics, UNSW, Sydney 2052 (Australia); Rossi, A.; Zhao, R. [School of Electrical Engineering and Telecommunications, UNSW, Sydney 2052 (Australia); Kafanov, S.; Duty, T. L. [School of Physics, UNSW, Sydney 2052 (Australia); Centre for Engineered Quantum Systems (EQuS), School of Physics, UNSW, Sydney 2052 (Australia); Dzurak, A. S. [School of Electrical Engineering and Telecommunications, UNSW, Sydney 2052 (Australia); Australian Centre of Excellence for Quantum Computation and Communication Technology (CQC2T), UNSW, Sydney 2052 (Australia); Rogge, S.; Tettamanzi, G. C., E-mail: g.tettamanzi@unsw.edu.au [School of Physics, UNSW, Sydney 2052 (Australia); Australian Centre of Excellence for Quantum Computation and Communication Technology (CQC2T), UNSW, Sydney 2052 (Australia)

    2015-08-10

    Schottky Barrier-MOSFET technology offers intriguing possibilities for cryogenic nano-scale devices, such as Si quantum devices and superconducting devices. We present experimental results on a device architecture where the gate electrode is self-aligned with the device channel and overlaps the source and drain electrodes. This facilitates a sub-5 nm gap between the source/drain and channel, and no spacers are required. At cryogenic temperatures, such devices function as p-MOS Tunnel FETs, as determined by the Schottky barrier at the Al-Si interface, and as a further advantage, fabrication processes are compatible with both CMOS and superconducting logic technology.

  8. High-voltage (> 1 kV) SiC Schottky barrier diodes with low on-resistance

    Energy Technology Data Exchange (ETDEWEB)

    Kimoto, Tsunenobu; Urushidani, Tatsuo; Kobayashi, Sota; Matsunami, Hiroyuki (Kyoto Univ. (Japan). Dept. of Electrical Engineering)

    1993-12-01

    Au/6H-SiC Schottky barrier diodes with high blocking voltages were successfully fabricated using layers grown by step-controlled epitaxy. A breakdown voltage over 1,100 V could be achieved, which is the highest ever reported for silicon carbide (SiC) Schottky barrier diodes. These high-voltage SiC rectifiers had specific on-resistances lower than the theoretical limits of Si rectifiers by more than one order of magnitude. The specific on-resistance increased with temperature according to T[sup 2.0] dependence. The diodes showed good characteristics at temperature as high as 400 C.

  9. Controllable Schottky barrier in GaSe/graphene heterostructure: the role of interface dipole

    Science.gov (United States)

    Si, Chen; Lin, Zuzhang; Zhou, Jian; Sun, Zhimei

    2017-03-01

    The discoveries of graphene and other related two-dimensional crystals have recently led to a new technology: van der Waals (vdW) heterostructures based on these atomically thin materials. Such a paradigm has been proved promising for a wide range of applications from nanoelectronics to optoelectronics and spintronics. Here, using first-principles calculations, we investigate the electronic structure and interface characteristics of a newly synthesized GaSe/graphene (GaSe/g) vdW heterostructure. We show that the intrinsic electronic properties of GaSe and graphene are both well preserved in the heterostructure, with a Schottky barrier formed at the GaSe/g interface. More interestingly, the band alignment between graphene and GaSe can be effectively modulated by tuning the interfacial distance or applying an external electric filed. This makes the Schottky barrier height (SBH) controllable, which is highly desirable in the electronic and optoelectronic devices based on vdW heterostructures. In particular, the tunability of the interface dipole and potential step is further uncovered to be the underlying mechanism that ensures this controllable tuning of SBH.

  10. Performance comparison of zero-Schottky-barrier and doped contacts carbon nanotube transistors with strain applied

    Institute of Scientific and Technical Information of China (English)

    Md Abdul Wahab; Khairul Alam

    2010-01-01

    Atomistic quantum simulation is performed to compare the performance of zero-Schottky-barrier and doped source-drain contacts carbon nanotube field effect transistors (CNTFETs) with strain applied. The doped source-drain contact CNTFETs outperform the Schottky contact devices with and without strain applied. The off-state current in both types of contact is similar with and without strain applied. This is because both types of contact offer very similar potential barrier in off-state. However, the on-state current in doped contact devices is much higher due to better modulation of on-state potential profile, and its variation with strain is sensitive to the device contact type. The on/off current ratio and the inverse subthreshold slope are better with doped source-drain contact, and their variations with strain are relatively less sensitive to the device contact type. The channel transconductance and device switching performance are much better with doped source-drain contact, and their variations with strain are sensitive to device contact type.

  11. Novel field-effect schottky barrier transistors based on graphene-MoS 2 heterojunctions

    KAUST Repository

    Tian, He

    2014-08-11

    Recently, two-dimensional materials such as molybdenum disulphide (MoS 2) have been demonstrated to realize field effect transistors (FET) with a large current on-off ratio. However, the carrier mobility in backgate MoS2 FET is rather low (typically 0.5-20 cm2/V.s). Here, we report a novel field-effect Schottky barrier transistors (FESBT) based on graphene-MoS2 heterojunction (GMH), where the characteristics of high mobility from graphene and high on-off ratio from MoS2 are properly balanced in the novel transistors. Large modulation on the device current (on/off ratio of 105) is achieved by adjusting the backgate (through 300 nm SiO2) voltage to modulate the graphene-MoS2 Schottky barrier. Moreover, the field effective mobility of the FESBT is up to 58.7 cm2/V.s. Our theoretical analysis shows that if the thickness of oxide is further reduced, a subthreshold swing (SS) of 40 mV/decade can be maintained within three orders of drain current at room temperature. This provides an opportunity to overcome the limitation of 60 mV/decade for conventional CMOS devices. The FESBT implemented with a high on-off ratio, a relatively high mobility and a low subthreshold promises low-voltage and low-power applications for future electronics.

  12. Schottky barrier and contact resistance of InSb nanowire field-effect transistors

    Science.gov (United States)

    Fan, Dingxun; Kang, N.; Gorji Ghalamestani, Sepideh; Dick, Kimberly A.; Xu, H. Q.

    2016-07-01

    Understanding of the electrical contact properties of semiconductor nanowire (NW) field-effect transistors (FETs) plays a crucial role in the use of semiconducting NWs as building blocks for future nanoelectronic devices and in the study of fundamental physics problems. Here, we report on a study of the contact properties of Ti/Au, a widely used contact metal combination, when contacting individual InSb NWs via both two-probe and four-probe transport measurements. We show that a Schottky barrier of height {{{Φ }}}{{SB}}˜ 20 {{meV}} is present at the metal-InSb NW interfaces and its effective height is gate-tunable. The contact resistance ({R}{{c}}) in the InSb NWFETs is also analyzed by magnetotransport measurements at low temperatures. It is found that {R}{{c}} in the on-state exhibits a pronounced magnetic field-dependent feature, namely it is increased strongly with increasing magnetic field after an onset field {B}{{c}}. A qualitative picture that takes into account magnetic depopulation of subbands in the NWs is provided to explain the observation. Our results provide solid experimental evidence for the presence of a Schottky barrier at Ti/Au-InSb NW interfaces and can be used as a basis for design and fabrication of novel InSb NW-based nanoelectronic devices and quantum devices.

  13. Electrical Characterization of High Energy Electron Irradiated Ni/4 H-SiC Schottky Barrier Diodes

    Science.gov (United States)

    Paradzah, A. T.; Omotoso, E.; Legodi, M. J.; Auret, F. D.; Meyer, W. E.; Diale, M.

    2016-08-01

    The effect of high energy electron irradiation on Ni/4 H-SiC Schottky barrier diodes was evaluated by current-voltage ( I- V) and capacitance-voltage ( C- V) measurements at room temperature. Electron irradiation was achieved by using a radioactive strontium source with peak emission energy of 2.3 MeV. Irradiation was performed in fluence steps of 4.9 × 1013 cm-2 until a total fluence of 5.4 × 1014 cm-2 was reached. The Schottky barrier height determined from I- V measurements was not significantly changed by irradiation while that obtained from C- V measurements increased with irradiation. The ideality factor was obtained before irradiation as 1.05 and this value did not significantly change as a result of irradiation. The series resistance increased from 47 Ω before irradiation to 74 Ω after a total electron fluence of 5.4 × 1014 cm-2. The net donor concentration decreased with increasing irradiation fluence from 4.6 × 1014 cm-3 to 3.0 × 1014 cm-3 from which the carrier removal rate was calculated to be 0.37 cm-1.

  14. The dependence of the Schottky barrier height on carbon nanotube diameter for Pd-carbon nanotube contacts

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Johannes; Sourab, Abdelrahim A; Campbell, Eleanor E B [Department of Physics, Goeteborg University, SE-41296 Goeteborg (Sweden); Tarakanov, Yury [Department of Applied Physics, Chalmers University of Technology, SE-41296 Gothenburg (Sweden); Lee, Dong Su [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Park, Seung Joo; Baek, Seung Jae; Park, Yung Woo [School of Physics, Seoul National University, Seoul 151-747 (Korea, Republic of)], E-mail: ywpark@phya.snu.ac.kr, E-mail: eleanor.campbell@ed.ac.uk

    2009-04-29

    Direct measurements are presented of the Schottky barrier (SB) heights of carbon nanotube devices contacted with Pd electrodes. The SB barrier heights were determined from the activation energy of the temperature-dependent thermionic emission current in the off-state of the devices. The barrier heights generally decrease with increasing diameter of the nanotubes and they are in agreement with the values expected when assuming little or no influence of Fermi level pinning.

  15. The dependence of the Schottky barrier height on carbon nanotube diameter for Pd-carbon nanotube contacts

    OpenAIRE

    Svensson, Johannes; Sourab, Abdelrahim A.; Tarakanov, Yury; Lee, Dong Su; Park, Seung Joo; Baek, Seung Jae; Park, Yung Woo; Campbell, Eleanor E. B.

    2009-01-01

    Direct measurements are presented of the Schottky barrier (SB) heights of carbon nanotube devices contacted with Pd electrodes. The SB barrier heights were determined from the activation energy of the temperature-dependent thermionic emission current in the off-state of the devices. The barrier heights generally decrease with increasing diameter of the nanotubes and they are in agreement with the values expected when assuming little or no influence of Fermi level pinning.

  16. Mechanisms of the degradation of Schottky-barrier photodiodes based on ZnS single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Korsunska, N. E.; Shulga, E. P.; Stara, T. R., E-mail: stara-t@ukr.net; Litvin, P. M.; Bondarenko, V. A. [National Academy of Sciences of Ukraine, Lashkarev Institute of Semiconductor Physics (Ukraine)

    2016-01-15

    The effect of ultraviolet (UV) illumination on the electrical and spectral characteristics of Schottky-barrier photodiodes based on ZnS single crystals is studied. It is found that irradiation deteriorates their photosensitivity and changes the current–voltage and capacitance–voltage characteristics and the surface profile of the blocking electrode. It is shown that the main reason for a decrease in the photosensitivity of the diodes is the photoinduced drift of mobile donors in the electric field of the barrier. This drift depends on the crystallographic orientation of the surface being irradiated. Another photoinduced process observed in the diodes is photolysis of the ZnS crystal. This process mainly determines the change in the electrical characteristics of the diodes and in the surface profile of the electrode at an insignificant change in the photosensitivity.

  17. Intermediate type excitons in Schottky barriers of A3B6 layer semiconductors and UV photodetectors

    Science.gov (United States)

    Alekperov, O. Z.; Guseinov, N. M.; Nadjafov, A. I.

    2006-09-01

    Photoelectric and photovoltaic spectra of Schottky barrier (SB) structures of InSe, GaSe and GaS layered semiconductors (LS) are investigated at quantum energies from the band edge excitons of corresponding materials up to 6.5eV. Spectral dependences of photoconductivity (PC) of photo resistors and barrier structures are strongly different at the quantum energies corresponding to the intermediate type excitons (ITE) observed in these semiconductors. It was suggested that high UV photoconductivity of A3B6 LS is due to existence of high mobility light carriers in the depth of the band structure. It is shown that SB of semitransparent Au-InSe is high sensitive photo detector in UV region of spectra.

  18. Ni/SiC–6H Schottky Barrier Diode interfacial states characterization related to temperature

    Energy Technology Data Exchange (ETDEWEB)

    Benamara, Mekki [Applied Microelectronics Laboratory (AMEL), Electronics Department, Faculty of Technology, Djillali Liabes University of Sidi Bel Abbes, BP 89, 22000 Sidi Bel Abbes (Algeria); Anani, Macho, E-mail: anani66@yahoo.fr [Laboratoire des Réseaux de Communications, d’Architecture et de Multimédia, Electronics Department, Faculty of Technology, Djillali Liabes University of Sidi Bel Abbes, BP 89, 22000 Sidi Bel Abbes (Algeria); Akkal, Boudali; Benamara, Zineb [Applied Microelectronics Laboratory (AMEL), Electronics Department, Faculty of Technology, Djillali Liabes University of Sidi Bel Abbes, BP 89, 22000 Sidi Bel Abbes (Algeria)

    2014-08-01

    Highlights: • This article is dealing with the evaluation of the mean interfacial states density of a Ni/SiC–6H Schottky Barrier Diode related to temperature. It appears a phenomenon of two barriers materializing one high diode and one low one. The other conclusion is that the interfacial states are diminishing when temperature is increasing. • This article has not, also, been published previously, is not under consideration for publication elsewhere, and its publication is approved by all authors. • The article has been correctly and thoroughly inspected and revised according to the reviewers’ recommendations. - Abstract: This study presents a Ni/SiC–6H Schottky Barrier Diode (SBD) characterization at different temperatures going from 77 K to 450 K. The electronic properties of this diode were reported by the analysis of its C(V{sub G}) and I(V{sub G}) characteristics as a function of temperature. At low temperature when T < 100 K the high part ideality factors n{sup H} were close to 2 showing that the conduction is dominated by the generation–recombination at deep centers. Also, the values of low part ideality factor n{sup L} varied from 2.69 down to 1.89. These values were also much closer to 2, showing that the conduction mechanism was then dominated by a tunneling current assisted by default. The mean interfacial states density D{sub s(mean)} decreased with increasing temperature from 1.2×10{sup 13} eV{sup −1} cm{sup −2} to 6.3 × 10{sup 12} eV{sup −1} cm{sup −2}. This reducing appeared to be due to the restructuring and rearrangement which occurs under molecules thermal activation within the Ni/SiC–6H metal/semiconductor interface.

  19. Inhomogeneous barrier height effect on the current-voltage characteristics of an Au/n-InP Schottky diode

    Science.gov (United States)

    Zeghdar, Kamal; Dehimi, Lakhdar; Saadoune, Achour; Sengouga, Nouredine

    2015-12-01

    We report the current-voltage (I-V) characteristics of the Schottky diode (Au/n-InP) as a function of temperature. The SILVACO-TCAD numerical simulator is used to calculate the I-V characteristic in the temperature range of 280-400 K. This is to study the effect of temperature on the I-V curves and assess the main parameters that characterize the Schottky diode such as the ideality factor, the height of the barrier and the series resistance. The I-V characteristics are analyzed on the basis of standard thermionic emission (TE) theory and the inhomogeneous barrier heights (BHs) assuming a Gaussian distribution. It is shown that the ideality factor decreases while the barrier height increases with increasing temperature, on the basis of TE theory. Furthermore, the homogeneous BH value of approximately 0.524 eV for the device has been obtained from the linear relationship between the temperature-dependent experimentally effective BHs and ideality factors. The modified Richardson plot, according to the inhomogeneity of the BHs, has a good linearity over the temperature range. The evaluated Richardson constant A* was 10.32 A·cm-2·K-2, which is close to the theoretical value of 9.4 A·cm-2·K-2 for n-InP. The temperature dependence of the I-V characteristics of the Au/n-InP Schottky diode have been successfully explained on the basis of the thermionic emission (TE) mechanism with a Gaussian distribution of the Schottky barrier heights (SBHs). Simulated I-V characteristics are in good agreement with the measurements [Korucu D, Mammadov T S. J Optoelectronics Advanced Materials, 2012, 14: 41]. The barrier height obtained using Gaussian Schottky barrier distribution is 0.52 eV, which is about half the band gap of InP.

  20. Barrier Enhancement Effect of Postannealing in Oxygen Ambient on Ni/AlGaN Schottky Contacts

    Institute of Scientific and Technical Information of China (English)

    SANG Li-Wen; QIN Zhi-Xin; CEN Long-Bin; CHEN Zhi-Zhong; YANG Zhi-Jian; SHEN Bo; ZHANG Guo-Yi

    2007-01-01

    Al0.2Ga0.sN/GaN samples are grown by metalorganic chemical vapour deposition (MOCVD) method on (0001) sapphire substrates. A 10nm-thick Ni layer is deposited on AlGaN as the transparent Schottky contact. The effect of postannealing in oxygen ambient on the electrical properties of Ni/AlGaN is studied by current voltagetemperature (I-V-T) measurement. The annealing at a relatively low temperature of 300℃ for 90 s results in a decrease of the ideality factor from 2.03 to 1.30 and an increase of the Schottky barrier height from 0.77eV to 0.954 eV. The I-V-T analysis confirms the improvement originated from the formation of NiO, a layer with higher resistatce, which could passivate the surface states of AlGaN and suppress the tunnelling current. Furthermore,the annealing also leads to an increase of the transmittance of the contacts from 57.5% to 78.2%, which would be favourable for AlGaN-based photodetectors.

  1. Zinc Selenide-Based Schottky Barrier Detectors for Ultraviolet-A and Ultraviolet-B Detection

    Directory of Open Access Journals (Sweden)

    V. Naval

    2010-01-01

    Full Text Available Wide-bandgap semiconductors such as zinc selenide (ZnSe have become popular for ultraviolet (UV photodetectors due to their broad UV spectral response. Schottky barrier detectors made of ZnSe in particular have been shown to have both low dark current and high responsivity. This paper presents the results of electrical and optical characterization of UV sensors based on ZnSe/Ni Schottky diodes fabricated using single-crystal ZnSe substrate with integrated UV-A (320–400 nm and UV-B (280–320 nm filters. For comparison, characteristics characterization of an unfiltered detector is also included. The measured photoresponse showed good discrimination between the two spectral bands. The measured responsivities of the UV-A and UV-B detectors were 50 mA/W and 10 mA/W, respectively. A detector without a UV filter showed a maximum responsivity of about 110 mA/W at 375 nm wavelength. The speed of the unfiltered detector was found to be about 300 kHz primarily limited by the RC time constant determined largely by the detector area.

  2. Temperature-dependent Schottky barrier in high-performance organic solar cells

    Science.gov (United States)

    Li, Hui; He, Dan; Zhou, Qing; Mao, Peng; Cao, Jiamin; Ding, Liming; Wang, Jizheng

    2017-01-01

    Organic solar cells (OSCs) have attracted great attention in the past 30 years, and the power conversion efficiency (PCE) now reaches around 10%, largely owning to the rapid material developments. Meanwhile with the progress in the device performance, more and more interests are turning to understanding the fundamental physics inside the OSCs. In the conventional bulk-heterojunction architecture, only recently it is realized that the blend/cathode Schottky junction serves as the fundamental diode for the photovoltaic function. However, few researches have focused on such junctions, and their physical properties are far from being well-understood. In this paper based on PThBDTP:PC71BM blend, we fabricated OSCs with PCE exceeding 10%, and investigated temperature-dependent behaviors of the junction diodes by various characterization including current-voltage, capacitance-voltage and impedance measurements between 70 to 290 K. We found the Schottky barrier height exhibits large inhomogeneity, which can be described by two sets of Gaussian distributions.

  3. Fabrication of a 600-V/20-A 4H-SiC schottky barrier diode

    Science.gov (United States)

    Kang, In-Ho; Kim, Sang-Cheol; Moon, Jung-Hyeon; Bahng, Wook; Kim, Nam-Kyun

    2014-06-01

    In this study, 600-V/20-A 4H-SiC Schottky barrier diodes (SBDs) were fabricated to investigate the effect of key processing steps, especially before and after the formation of a Schottky contact, on the electrical performances of SBDs and on their long-term reliabilities. The results show that 4H-SiC SBDs that had been subjected to a hydrogen-ambient annealing at 470 °C for 10 min and sacrificial treatment right after ion activation exhibited a lower forward voltage drop (V F ) at a rated current of 20 A, a higher blocking voltage of 800 V, and a very short reverse recovery time of 17.5 ns. Despite the harsh reverse bias condition and temperature, a long-term reliability test showed that changes in the forward voltage drop and the reverse leakage current (I R ) were 0.7% and 8.9% and that the blocking voltage was enhanced. This is attributed to the presence of a stabilized interface between the passivation layer and the SiC due to aging.

  4. Schottky barrier heights at the interfaces between pure-phase InAs nanowires and metal contacts

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Boyong; Huang, Shaoyun, E-mail: syhuang@pku.edu.cn, E-mail: hqxu@pku.edu.cn; Wang, Jiyin [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China); Pan, Dong; Zhao, Jianghua [State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Xu, H. Q., E-mail: syhuang@pku.edu.cn, E-mail: hqxu@pku.edu.cn [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China); Division of Solid-State Physics, Lund University, Box 118, S-221 00 Lund (Sweden)

    2016-02-07

    Understanding of the Schottky barriers formed at metal contact-InAs nanowire interfaces is of great importance for the development of high-performance InAs nanowire nanoelectronic and quantum devices. Here, we report a systematical study of InAs nanowire field-effect transistors (FETs) and the Schottky barrier heights formed at the contact-nanowire interfaces. The InAs nanowires employed are grown by molecular beam epitaxy and are high material quality single crystals, and the devices are made by directly contacting the nanowires with a series of metals of different work functions. The fabricated InAs nanowire FET devices are characterized by electrical measurements at different temperatures and the Schottky barrier heights are extracted from the measured temperature and gate-voltage dependences of the channel current. We show that although the work functions of the contact metals are widely spread, the Schottky barrier heights are determined to be distributed over 35–55 meV, showing a weak but not negligible dependence on the metals. The deduced Fermi level in the InAs nanowire channels is found to be in the band gap and very close to the conduction band. The physical origin of the results is discussed in terms of Fermi level pinning by the surface states of the InAs nanowires and a shift in pinned Fermi level induced by the metal-related interface states.

  5. Field plate engineering for GaN-based Schottky barrier diodes

    Institute of Scientific and Technical Information of China (English)

    Lei Yong; Shi Hongbiao; Lu Hai; Chen Dunjun; Zhang Rong; Zheng Youdou

    2013-01-01

    The practical design of GaN-based Schottky barrier diodes (SBDs) incorporating a field plate (FP)structure necessitates an understanding of their working mechanism and optimization criteria.In this work,the influences of the parameters of FPs upon breakdown of the diode are investigated in detail and the design rules of FP structures for GaN-based SBDs are presented for a wide scale of material and device parameters.By comparing three representative dielectric materials (SiO2,Si3N4 and A12O3) selected for fabricating FPs,it is found that the product of dielectric permittivity and critical field strength of a dielectric material could be used as an index to predict its potential performance for FP applications.

  6. Formation and Schottky barrier height of Au contacts to CuInSe sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, A.J.; Gebhard, S.; Kazmerski, L.L. (Solar Energy Research Institute, Golden, Colorado 80401 (USA)); Colavita, E. (Physics Department, University of Calabria, 87036 Arcavacata di Rende, Cosenza, Italy (IT)); Engelhardt, M.; Hoechst, H. (Synchrotron Radiation Center, University of Wisconsin-Madison, Stoughton, Wisconsin 53589 (USA))

    1991-05-01

    Synchrotron radiation soft x-ray photoemission spectroscopy was used to investigate the development of the electronic structure at the Au/CuInSe{sub 2} interface. Au overlayers were deposited in steps on single-crystal {ital p} and {ital n}-type CuInSe{sub 2} at ambient temperature. Reflection high-energy electron diffraction analysis before and during growth of the Au overlayers indicated that the Au overlayer was amorphous. Photoemission measurements were acquired after each growth in order to observe changes in the valence band electronic structure as well as changes in the In 4{ital d} and Se 3{ital d} core lines. The results were used to correlate the interface chemistry with the electronic structure at these interfaces and to directly determine the Au/CuInSe{sub 2} Schottky barrier height.

  7. Schottky barrier at graphene/metal oxide interfaces: insight from first-principles calculations

    Science.gov (United States)

    Cheng, Kai; Han, Nannan; Su, Yan; Zhang, Junfeng; Zhao, Jijun

    2017-02-01

    Anode materials play an important role in determining the performance of lithium ion batteries. In experiment, graphene (GR)/metal oxide (MO) composites possess excellent electrochemical properties and are promising anode materials. Here we perform density functional theory calculations to explore the interfacial interaction between GR and MO. Our result reveals generally weak physical interactions between GR and several MOs (including Cu2O, NiO). The Schottky barrier height (SBH) in these metal/semiconductor heterostructures are computed using the macroscopically averaged electrostatic potential method, and the role of interfacial dipole is discussed. The calculated SBHs below 1 eV suggest low contact resistance; thus these GR/MO composites are favorable anode materials for better lithium ion batteries.

  8. A performance optimization and analysis of graphene based schottky barrier GaAs solar cell

    Science.gov (United States)

    Jolson Singh, Khomdram; Chettri, Dhanu; Jayenta Singh, Thokchom; Thingujam, Terirama; Sarkar, Subir kumar

    2017-06-01

    Performance optimization of Graphene-GaAs schottky barrier solar cell have been performed by considering variables such as substrate thickness, Graphene thickness, dependence between graphene work function and transmittance. The optimized parameter was extensively used to numerically model the design using TCAD Atlas. The results show the enhanced performance of the design with the optimized thickness of Graphene (0.3μm) and GaAs (10μm), resulting in significant increase in power conversion efficiency from 0.732% to 2.581% and reasonable fill factor up to 70%. It was further analysed that maximum potential was developed in the vicinity of the anode, which results in better charge collection hence improving the overall performance of the solar cell. The results are validated with the reported experimental work.

  9. Characterization of breakdown behavior of diamond Schottky barrier diodes using impact ionization coefficients

    Science.gov (United States)

    Driche, Khaled; Umezawa, Hitoshi; Rouger, Nicolas; Chicot, Gauthier; Gheeraert, Etienne

    2017-04-01

    Diamond has the advantage of having an exceptionally high critical electric field owing to its large band gap, which implies its high ability to withstand high voltages. At this maximum electric field, the operation of Schottky barrier diodes (SBDs), as well as FETs, may be limited by impact ionization, leading to avalanche multiplication, and hence the devices may breakdown. In this study, three of the reported impact ionization coefficients for electrons, αn, and holes, αp, in diamond at room temperature (300 K) are analyzed. Experimental data on reverse operation characteristics obtained from two different diamond SBDs are compared with those obtained from their corresponding simulated structures. Owing to the crucial role played by the impact ionization rate in determining the carrier transport, the three reported avalanche parameters implemented affect the behavior not only of the breakdown voltage but also of the leakage current for the same structure.

  10. Schottky barrier at graphene/metal oxide interfaces: insight from first-principles calculations

    Science.gov (United States)

    Cheng, Kai; Han, Nannan; Su, Yan; Zhang, Junfeng; Zhao, Jijun

    2017-01-01

    Anode materials play an important role in determining the performance of lithium ion batteries. In experiment, graphene (GR)/metal oxide (MO) composites possess excellent electrochemical properties and are promising anode materials. Here we perform density functional theory calculations to explore the interfacial interaction between GR and MO. Our result reveals generally weak physical interactions between GR and several MOs (including Cu2O, NiO). The Schottky barrier height (SBH) in these metal/semiconductor heterostructures are computed using the macroscopically averaged electrostatic potential method, and the role of interfacial dipole is discussed. The calculated SBHs below 1 eV suggest low contact resistance; thus these GR/MO composites are favorable anode materials for better lithium ion batteries. PMID:28165485

  11. Evaluation of Schottky barrier diodes fabricated directly on processed 4H-SiC(0001) surfaces.

    Science.gov (United States)

    Sano, Yasuhisa; Shirasawa, Yuki; Okamoto, Takeshi; Yamauchi, Kazuto

    2011-04-01

    Silicon carbide (SiC) is a suitable substrate for low-power-consumption power devices and high-temperature applications. However, this material is difficult to machine because of its hardness and chemical inertness, and many machining methods have been studied intensively in recent years. In this paper, we present a simple method to evaluate the electrical properties of the processed surface using the ideal factor n of a Schottky barrier diode (SBD) fabricated directly on the processed surface. Upon comparing the values of n for SBDs fabricated on a damaged SiC surface and a non-damaged SiC surface, we found that there is a significant difference in the dispersion and magnitude of n. Furthermore, by combining this technique with slope etching, we were able to estimate the thickness of the damaged sub-surface layer.

  12. Heavy ion-induced damage in SiC Schottky barrier diode

    Energy Technology Data Exchange (ETDEWEB)

    Kamezawa, C. [Japan Aerospace Exploration Agency, Tsukuba Space Center, 2-1-1 Sengen, Ibaraki 305-8505 (Japan)]. E-mail: kamezawa.chihiro@jaxa.jp; Sindou, H. [Japan Aerospace Exploration Agency, Tsukuba Space Center, 2-1-1 Sengen, Ibaraki 305-8505 (Japan); Hirao, T. [Japan Atomic Energy Research Institute, Gunma 370-1292 (Japan); Ohyama, H. [Kumamoto National College of Technology, Kumamoto 861-1102 (Japan); Kuboyama, S. [Japan Aerospace Exploration Agency, Tsukuba Space Center, 2-1-1 Sengen, Ibaraki 305-8505 (Japan)

    2006-04-01

    Silicon carbide (SiC) is a very promising material for future electronic devices. Also it is an attractive material for space applications, that require long-term endurance and higher efficiency, where tolerance to space radiations is a major problem. In this study, we have performed some irradiation examinations and evaluations on a commercial SiC Schottky barrier diode by looking at the damage caused by ion incidence using heavy ions. Ions of Xe, Kr, Ar, Ne, and N, with specific energies, were used in the irradiation process. Sudden breakdown condition at higher bias voltage and gradual damage created by heavy ion incidence were confirmed. The collected charge spectra were also obtained and revealed mechanisms that resulted to permanent damage. The observed anomalous charge collection was an essential factor for the susceptibility. This indicates a problem that need to be solved in the future for SiC space application.

  13. Defect-induced performance degradation of 4H-SiC Schottky barrier diode particle detectors

    Science.gov (United States)

    Iwamoto, N.; Johnson, B. C.; Hoshino, N.; Ito, M.; Tsuchida, H.; Kojima, K.; Ohshima, T.

    2013-04-01

    The formation and evolution of defects in 4H-SiC Schottky barrier diode high-energy particle detectors have been investigated and correlated with the detectors' properties. Low temperature annealing at 300 °C is found to significantly recover the charge collection efficiency as degraded by 1 MeV electron irradiation. At higher temperatures, an anneal-induced degradation in the detector's performance is observed. Current-voltage, capacitance-voltage, and deep level transient spectroscopy (DLTS) measurements are used to ascertain the effect of defects on the detector performance. The latter reveals that the DLTS defect levels, EH1 and EH3, are related to the initial recovery of the charge collection efficiency.

  14. Tuning a Schottky barrier of epitaxial graphene/4H-SiC (0001) by hydrogen intercalation

    Science.gov (United States)

    Dharmaraj, P.; Justin Jesuraj, P.; Jeganathan, K.

    2016-02-01

    We report the electron transport properties of epitaxial graphene (EG) grown on 4H-SiC (0001) by low energy electron-beam irradiation. As-grown EG (AEG) on SiC interface exhibits rectifying current-voltage characteristics with a low Schottky barrier (SB) of 0.55 ± 0.05 eV and high reverse current leakage. The SB of AEG/SiC junction is extremely impeded by the Fermi level pinning (FLP) above the Dirac point due to charged states at the interface. Nevertheless, a gentle hydrogen intercalation at 900 °C enables the alleviation of both FLP and carrier scattering owing to the saturation of dangling bonds as evidenced by the enhancement of SB (0.75 ± 0.05 eV) and high electron mobility well excess of 6000 cm2 V-1 s-1.

  15. Analysis on partial thermal resistances of packaged SiC schottky barrier diodes at elevated temperatures

    Science.gov (United States)

    Kim, Taehwa; Funaki, Tsuyoshi

    2016-04-01

    This paper investigates the temperature dependence of partial thermal resistances of a packaged SiC schottky barrier diode (SBD) for high temperature applications. Transient thermal resistances of the packaged SiC SBD were measured and characterized in temperature range from 27 to 275 °C. The partial thermal resistances were extracted and analyzed using the cumulative and differential thermal structure functions. The extracted partial thermal resistances were compared to the results from the finite difference thermal model, and both results were in good agreement. The temperature dependence of the partial thermal resistance of the SiC device and the Si3N4 substrate contributes to the overall thermal characteristics variation of the packaged SiC SBD.

  16. A comparative study of IR Ge photodiodes with a Schottky barrier contact and metal-semiconductor-metal structure

    Energy Technology Data Exchange (ETDEWEB)

    Khurelbaatar, Zagarzusem; Kil, Yeonho; Lee, Hunki; Yang, Jonghan; Kang, Sukill; Kim, Taeksung; Shim, Kyuhwan [Chonbuk National University, Jeonju (Korea, Republic of)

    2014-12-15

    We report the characterization of germanium (Ge) infrared photodiodes fabricated with a Schottky barrier contact and a interdigitated metal-semiconductor-metal (MSM) structure with gold electrodes on n-Ge substrates. The current-volage (I-V) characteristics were studied, and parameters such as the ideality factor and the barrier height of the Schottky contacts were extracted. Furthemore, we estimated the dark current and the photocurrent under illumination with λ = 1550 nm light, and we measured the capacitance-voltage (C-V) characteristics and the dependence of the responsivity on the bias voltage of both photodiodes at room temperature. The dark currents of the Schottky and the MSM photodiodes were ∼ 20.2 μA and ∼ 26.0 μA under .1 V bias and .2 V bias, respectively. In addition, the reverse breakdown voltage was high, in excess of ∼ -30 V. The Schottky barrier height was deduced to be 0.546 eV. A maximum responsivity of 0.27 A/W was achieved under illumination with λ = 1550 nm light at a 2-V bias. A typical peak was observed at a wavelength of 1600 nm, and a high responsivity was observed in the wavelength range from 1200 to 1800 nm.

  17. The modulation of Schottky barriers of metal-MoS2 contacts via BN-MoS2 heterostructures.

    Science.gov (United States)

    Su, Jie; Feng, Liping; Zhang, Yan; Liu, Zhengtang

    2016-06-22

    Using first-principles calculations within density functional theory, we systematically studied the effect of BN-MoS2 heterostructure on the Schottky barriers of metal-MoS2 contacts. Two types of FETs are designed according to the area of the BN-MoS2 heterostructure. Results show that the vertical and lateral Schottky barriers in all the studied contacts, irrespective of the work function of the metal, are significantly reduced or even vanish when the BN-MoS2 heterostructure substitutes the monolayer MoS2. Only the n-type lateral Schottky barrier of Au/BN-MoS2 contact relates to the area of the BN-MoS2 heterostructure. Notably, the Pt-MoS2 contact with n-type character is transformed into a p-type contact upon substituting the monolayer MoS2 by a BN-MoS2 heterostructure. These changes of the contact natures are ascribed to the variation of Fermi level pinning, work function and charge distribution. Analysis demonstrates that the Fermi level pinning effects are significantly weakened for metal/BN-MoS2 contacts because no gap states dominated by MoS2 are formed, in contrast to those of metal-MoS2 contacts. Although additional BN layers reduce the interlayer interaction and the work function of the metal, the Schottky barriers of metal/BN-MoS2 contacts still do not obey the Schottky-Mott rule. Moreover, different from metal-MoS2 contacts, the charges transfer from electrodes to the monolayer MoS2, resulting in an increment of the work function of these metals in metal/BN-MoS2 contacts. These findings may prove to be instrumental in the future design of new MoS2-based FETs with ohmic contact or p-type character.

  18. InGaAs Schottky barrier diode array detectors integrated with broadband antenna (Conference Presentation)

    Science.gov (United States)

    Park, Dong Woo; Lee, Eui Su; Park, Jeong-Woo; Kim, Hyun-Soo; Lee, Il-Min; Park, Kyung Hyun

    2017-02-01

    Terahertz (THz) waves have been actively studied for the applications of astronomy, communications, analytical science and bio-technologies due to their low energy and high frequency. For example, THz systems can carry more information with faster rates than GHz systems. Besides, THz waves can be applied to imaging, sensing, and spectroscopy. Furthermore, THz waves can be used for non-destructive and non-harmful tomography of living objects. In this reasons, Schottky barrier diodes (SBD) have been widely used as a THz detector for their ultrafast carrier transport, high responsivity, high sensitivity, and excellent noise equivalent power. Furthermore, SBD detectors envisage developing THz applications at low cost, excellent capability, and high yield. Since the major concerns in the THz detectors for THz imaging systems are the realizations of the real-time image acquisitions via a reduced acquisition time, rather than the conventional raster scans that obtains an image by pixel-by-pixel acquisitions, a line-scan based systems utilizes an array detector with an 1 × n SBD array is preferable. In this study, we fabricated the InGaAs based SBD array detectors with broadband antennas of log-spiral and square-spiral patterns. To optimize leakage current and ideality factor, the dependence to the doping levels of ohmic and Schottky layers have been investigated. In addition, the dependence to the capacitance and resistance to anode size are also examined as well. As a consequence, the real-time THz imaging with our InGaAs SBD array detector have been successfully obtained.

  19. Study of Au, Ni-(n)ZnSe Thin Film Schottky Barrier Junctions

    Science.gov (United States)

    Chaliha, Sumbit; Borah, Mothura Nath; Sarmah, P. C.; Rahman, A.

    2010-10-01

    Schottky barrier junctions of Al-doped n-type Zinc selenide (ZnSe) thin films of doping concentrations up to 9.7 × 1014 cm -3 have been fabricated with Au and Ni electrodes on glass substrates by sequential thermal evaporation. All of the junctions of different doping concentrations exhibited rectifying current-voltage characteristics with a non-saturating reverse current. From the current-voltage characteristics, the different junction parameters such as ideality factor, saturation current density, series resistance, etc., were measured. Both types of junctions were found to possess a high ideality factor and a high series resistance. The barrier heights of the junctions were measured from Richardson plots and found to be around 0.8 eV. The structures were found to exhibit a poor photovoltaic effect with a fill factor not greater than 0.4. The diode quality as well as the photovoltaic performance of the diodes were improved following a short heat treatment in vacuum.

  20. Highly sensitive NIR PtSi/Si-nanostructure detectors

    Science.gov (United States)

    Li, Hua-gao; Guo, Pei; Yuan, An-bo; Long, Fei; Li, Rui-zhi; Li, Ping; Li, Yi

    2016-10-01

    We report a high external quantum efficiency (EQE) photodiode detector with PtSi/Si-nanostructures. Black silicon nanostructures were fabricated by metal-assist chemical etching (MCE), a 2 nm Pt layer was subsequently deposited on black silicon surface by DC magnetron sputtering system, and PtSi/Si-nanostructures were formed in vacuum annealing at 450 oC for 5 min. As the PtSi/Si-nanostructures presented a spiky shape, the absorption of incident light was remarkably enhanced for the repeat reflection and absorption. The breakdown voltage, dark current, threshold voltage and responsivity of the device were investigated to evaluate the performance of the PtSi/Si-nanostructures detector. The threshold voltage and dark currents of the PtSi/Si-nanostructure photodiode tends to be slightly higher than those of the standard diodes. The breakdown voltage remarkably was reduced because of existing avalanche breakdown in PtSi/Si-nanostructures. However, the photodiodes had high response at room temperature in near infrared region. At -5 V reverse bias voltage, the responsivity was 0.72 A/W in 1064 nm wavelength, and the EQE was 83.9%. By increasing the reverse bias voltage, the responsivity increased. At -60 V reverse bias voltage, the responsivity was 3.5 A/W, and the EQE was 407.5%, which means the quantum efficiency of PtSi/Si-nanostructure photodiodes was about 10 times higher than that of a standard diode. Future research includes how to apply this technology to enhance the NIR sensitivity of image sensors, such as Charge Coupled Devices (CCD).

  1. Room temperature current-voltage (I-V) characteristics of Ag/InGaN/n-Si Schottky barrier diode

    Science.gov (United States)

    Erdoğan, Erman; Kundakçı, Mutlu

    2017-02-01

    Metal-semiconductors (MSs) or Schottky barrier diodes (SBDs) have a significant potential in the integrated device technology. In the present paper, electrical characterization of Ag/InGaN/n-Si Schottky diode have been systematically carried out by simple Thermionic method (TE) and Norde function based on the I-V characteristics. Ag ohmic and schottky contacts are deposited on InGaN/n-Si film by thermal evaporation technique under a vacuum pressure of 1×10-5 mbar. Ideality factor, barrier height and series resistance values of this diode are determined from I-V curve. These parameters are calculated by TE and Norde methods and findings are given in a comparetive manner. The results show the consistency for both method and also good agreement with other results obtained in the literature. The value of ideality factor and barrier height have been determined to be 2.84 and 0.78 eV at room temperature using simple TE method. The value of barrier height obtained with Norde method is calculated as 0.79 eV.

  2. Electric field modulation of Schottky barrier height in graphene/MoSe{sub 2} van der Waals heterointerface

    Energy Technology Data Exchange (ETDEWEB)

    Sata, Yohta; Moriya, Rai, E-mail: moriyar@iis.u-tokyo.ac.jp, E-mail: tmachida@iis.u-tokyo.ac.jp; Morikawa, Sei; Yabuki, Naoto [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan); Masubuchi, Satoru; Machida, Tomoki, E-mail: moriyar@iis.u-tokyo.ac.jp, E-mail: tmachida@iis.u-tokyo.ac.jp [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan); Institute for Nano Quantum Information Electronics, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan)

    2015-07-13

    We demonstrate a vertical field-effect transistor based on a graphene/MoSe{sub 2} van der Waals (vdW) heterostructure. The vdW interface between the graphene and MoSe{sub 2} exhibits a Schottky barrier with an ideality factor of around 1.3, suggesting a high-quality interface. Owing to the low density of states in graphene, the position of the Fermi level in the graphene can be strongly modulated by an external electric field. Therefore, the Schottky barrier height at the graphene/MoSe{sub 2} vdW interface is also modulated. We demonstrate a large current ON-OFF ratio of 10{sup 5}. These results point to the potential high performance of the graphene/MoSe{sub 2} vdW heterostructure for electronics applications.

  3. Effect of temperature on the carrier transport property of 4H-SiC based Schottky barrier diode

    Directory of Open Access Journals (Sweden)

    TONG Wulin

    2015-08-01

    Full Text Available In this paper,the current-voltage (I-V measurement under different temperatures was carried out on the 4H-SiC Schottky barrier diode (SBD purchased from Cree Inc.The carrier transport mechanism and the temperature effect of SBD were investigated through the theoretical simulation based on the experimental data.The Schottky barrier height is decreased and leakage current is increased sharply for SBD when the temperatures are increased.The SBD forward bias obeys the hot electron emission mechanism.Taking the image force correction and tunneling effect into consideration,the high leakage current under reverse bias can be reasonably explained and is good agreement with the experiment results.

  4. Temperature dependence of the inhomogeneous parameters of the Mo/4H-SiC Schottky barrier diodes

    Science.gov (United States)

    Latreche, A.; Ouennoughi, Z.; Weiss, R.

    2016-08-01

    The inhomogeneous parameters of Mo/4H-SiC Schottky barrier diodes were determined from current-voltage (I-V) characteristics in the temperature range of 303-498 K by using a general approach for the real Schottky diode. In this approach the total series resistances is divided into two resistances; the first one (R P) is the sum of the series resistances (r) of the particular diodes connected in parallel and the second is the common resistance (R C) to all particular diodes. The mean barrier height (\\bar{φ }) and the standard deviation (σ) decrease linearly with decreasing temperature and they are between the values for the diodes with the two limiting cases; no current spreading and full current spreading. The series resistance R C increases, while the series resistance R P slightly decreases with decreasing temperature.

  5. Development of an Astronomical Infrared PtSi Camera

    Science.gov (United States)

    Hong, S. S.; Ueno, M.; Koo, B. C.; Kim, K.-T.; Kim, C. Y.; Oh, K. S.; Lee, M. G.; Lee, H. M.; Kang, Y. W.; Park, W.-K.

    1996-12-01

    We have built a near-infrared imaging camera with a PtSi array detector manufactured the Mitsubishi Company. The PtSi detector is sensitive in the wavelength range 1 to 5micrometer. Quantum efficiency of PtSi is much lower than that of InSb and HgCdTe types. However, the PtSi array has advantages over the latter ones:(i)The read-out noise is very low;(ii)the characteristics of the array elements are uniform and stable; (iii)it is not difficult to make a large PtSi array; and (iv)consequently the price is affordably low. The array used consists of 512 x 512 pixels and its size is 10.2 mm x 13.3 mm. The filter wheel of the camera is equipped with J, H, K filters, and an aluminum plate for measuring the dark noise. The dewar is cooled with liquid nitrogen. We have adopted a method of installing the clock pattern and the observing softwares in the RAM, which can be easily used for other systems. We have developed a software with a pull-down menu for operating the camera and data acquisition. The camera has been tested by observing Orionis.

  6. Effect of graphene tunnel barrier on Schottky barrier height of Heusler alloy Co2MnSi/graphene/n-Ge junction

    Science.gov (United States)

    Gui-fang, Li; Jing, Hu; Hui, Lv; Zhijun, Cui; Xiaowei, Hou; Shibin, Liu; Yongqian, Du

    2016-02-01

    We demonstrate that the insertion of a graphene tunnel barrier between Heusler alloy Co2MnSi and the germanium (Ge) channel modulates the Schottky barrier height and the resistance-area product of the spin diode. We confirm that the Fermi level is depinned and a reduction in the electron Schottky barrier height (SBH) occurs following the insertion of the graphene layer between Co2MnSi and Ge. The electron SBH is modulated in the 0.34 eV-0.61 eV range. Furthermore, the transport mechanism changes from rectifying to symmetric tunneling following the insertion. This behavior provides a pathway for highly efficient spin injection from a Heusler alloy into a Ge channel with high electron and hole mobility. Project supported by the National Natural Science Foundation of China (Grant No. 61504107) and the Fundamental Research Funds for the Central Universities, China (Grant Nos. 3102014JCQ01059 and 3102015ZY043).

  7. Schottky barrier engineering via adsorbing gases at the sulfur vacancies in the metal-MoS2 interface.

    Science.gov (United States)

    Su, Jie; Feng, Liping; Zhang, Yan; Liu, Zhengtang

    2017-03-10

    Sulfur vacancies (S-vacancies) are common in monolayer MoS2 (mMoS2). Finding an effective way to control rather than abolish the effect of S-vacancies on contact properties is vital for the application of mMoS2. Here, we propose the adsorption of gases to passivate the S-vacancies in Pt-mMoS2 interfaces. Results demonstrate that gases are stably and preferentially adsorbed at S-vacancies. The n-type Schottky barriers of Pt-mMoS2 interfaces are reduced significantly upon the adsorption electron-donor gases, especially Cl2. The n-type transport character of the Pt-mMoS2 interface can be changed to p-type by the adsorption of electron-acceptor gases. As the adsorption concentration increases, both n- and p-type Schottky barriers are further reduced, and the lowest n- and p-type Schottky barriers are 0.36 and 0 eV, respectively. Note that the variations in Schottky barriers are independent of the oxidizing ability of gases but relative to the average number of valence electrons per gas atom. Analysis demonstrates that although gases at S-vacancies cannot cause gap states to vanish, and can even enhance Fermi level pinning, they modulate charge redistribution and the potential step at the interface region. Moreover, with increasing adsorption concentration, the valence band maximum of mMoS2 shows the opposite variation tendency to that of the potential step. Our results suggest that adsorption of gases is an effective way to passivate S-vacancies to modulate the transport properties of Pt-mMoS2 interfaces.

  8. Schottky barrier engineering via adsorbing gases at the sulfur vacancies in the metal–MoS2 interface

    Science.gov (United States)

    Su, Jie; Feng, Liping; Zhang, Yan; Liu, Zhengtang

    2017-03-01

    Sulfur vacancies (S-vacancies) are common in monolayer MoS2 (mMoS2). Finding an effective way to control rather than abolish the effect of S-vacancies on contact properties is vital for the application of mMoS2. Here, we propose the adsorption of gases to passivate the S-vacancies in Pt–mMoS2 interfaces. Results demonstrate that gases are stably and preferentially adsorbed at S-vacancies. The n-type Schottky barriers of Pt–mMoS2 interfaces are reduced significantly upon the adsorption electron-donor gases, especially Cl2. The n-type transport character of the Pt–mMoS2 interface can be changed to p-type by the adsorption of electron-acceptor gases. As the adsorption concentration increases, both n- and p-type Schottky barriers are further reduced, and the lowest n- and p-type Schottky barriers are 0.36 and 0 eV, respectively. Note that the variations in Schottky barriers are independent of the oxidizing ability of gases but relative to the average number of valence electrons per gas atom. Analysis demonstrates that although gases at S-vacancies cannot cause gap states to vanish, and can even enhance Fermi level pinning, they modulate charge redistribution and the potential step at the interface region. Moreover, with increasing adsorption concentration, the valence band maximum of mMoS2 shows the opposite variation tendency to that of the potential step. Our results suggest that adsorption of gases is an effective way to passivate S-vacancies to modulate the transport properties of Pt–mMoS2 interfaces.

  9. A new model of noise characteristics of SiC Schottky barrier MESFET with deep impurity levels and traps

    Energy Technology Data Exchange (ETDEWEB)

    Aroutiounian, V.M. [Yerevan State University, Al. Manoukian Str. 1, 375025 Yerevan (Armenia)]. E-mail: kisahar@ysu.am; Avetisyan, G.A. [Yerevan State University, Al. Manoukian Str. 1, 375025 Yerevan (Armenia); Buniatyan, V.V. [State Engineering University of Armenia, 105 Teryan Str., 375009 Yerevan (Armenia); Soukiassian, P.G. [Commissariat a l' Energie Atomique, Laboratoire Surfaces et Interfaces de Materiaux, Avances associe a l' Universite de Paris-Sud/Orsay, DSM-DRECAM-SPCSI, Batiment 462, Saclay, 91191 Gif sur Yvette Cedex (France); Buniatyan, Vaz.V. [State Engineering University of Armenia, 105 Teryan Str., 375009 Yerevan (Armenia)

    2006-05-30

    Noise characteristics of silicon carbide Schottky barrier field effect transistors (MESFET) are examined for the case of the operation in small-signal regime and the presence of deep impurity levels and electron traps in the band gap of the channel. A new model of calculations of noise is suggested. It is shown that the noise measure of the short channel MESFET can be decreased within certain high frequency range.

  10. Interface Engineering of Organic Schottky Barrier Solar Cells and Its Application in Enhancing Performances of Planar Heterojunction Solar Cells.

    Science.gov (United States)

    Jin, Fangming; Su, Zisheng; Chu, Bei; Cheng, Pengfei; Wang, Junbo; Zhao, Haifeng; Gao, Yuan; Yan, Xingwu; Li, Wenlian

    2016-05-17

    In this work, we describe the performance of organic Schottky barrier solar cells with the structure of ITO/molybdenum oxide (MoOx)/boron subphthalocyanine chloride (SubPc)/bathophenanthroline (BPhen)/Al. The SubPc-based Schottky barrier solar cells exhibited a short-circuit current density (Jsc) of 2.59 mA/cm(2), an open-circuit voltage (Voc) of 1.06 V, and a power conversion efficiency (PCE) of 0.82% under simulated AM1.5 G solar illumination at 100 mW/cm(2). Device performance was substantially enhanced by simply inserting thin organic hole transport material into the interface of MoOx and SubPc. The optimized devices realized a 180% increase in PCE of 2.30% and a peak Voc as high as 1.45 V was observed. We found that the improvement is due to the exciton and electron blocking effect of the interlayer and its thickness plays a vital role in balancing charge separation and suppressing quenching effect. Moreover, applying such interface engineering into MoOx/SubPc/C60 based planar heterojunction cells substantially enhanced the PCE of the device by 44%, from 3.48% to 5.03%. Finally, we also investigated the requirements of the interface material for Schottky barrier modification.

  11. Time dependent changes in Schottky barrier mapping of the W/Si(001) interface utilizing ballistic electron emission microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Durcan, Chris A.; Balsano, Robert [College of Nanoscale Science and Engineering, State University of New York, Albany, New York 12203 (United States); LaBella, Vincent P., E-mail: vlabella@albany.edu [Colleges of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York 12203 (United States)

    2015-06-28

    The W/Si(001) Schottky barrier height is mapped to nanoscale dimensions using ballistic electron emission microscopy (BEEM) over a period of 21 days to observe changes in the interface electrostatics. Initially, the average spectrum is fit to a Schottky barrier height of 0.71 eV, and the map is uniform with 98% of the spectra able to be fit. After 21 days, the average spectrum is fit to a Schottky barrier height of 0.62 eV, and the spatial map changes dramatically with only 27% of the spectra able to be fit. Transmission electron microscopy shows the formation of an ultra-thin tungsten silicide at the interface, which increases in thickness over the 21 days. This increase is attributed to an increase in electron scattering and the changes are observed in the BEEM measurements. Interestingly, little to no change is observed in the I-V measurements throughout the 21 day period.

  12. Monolayer graphene/SiC Schottky barrier diodes with improved barrier height uniformity as a sensing platform for the detection of heavy metals.

    Science.gov (United States)

    Shtepliuk, Ivan; Eriksson, Jens; Khranovskyy, Volodymyr; Iakimov, Tihomir; Lloyd Spetz, Anita; Yakimova, Rositsa

    2016-01-01

    A vertical diode structure comprising homogeneous monolayer epitaxial graphene on silicon carbide is fabricated by thermal decomposition of a Si-face 4H-SiC wafer in argon atmosphere. Current-voltage characteristics of the graphene/SiC Schottky junction were analyzed by applying the thermionic-emission theory. Extracted values of the Schottky barrier height and the ideality factor are found to be 0.4879 ± 0.013 eV and 1.01803 ± 0.0049, respectively. Deviations of these parameters from average values are smaller than those of previously observed literature data, thereby implying uniformity of the Schottky barrier height over the whole diode area, a stable rectifying behaviour and a good quality of ohmic palladium-graphene contacts. Keeping in mind the strong sensitivity of graphene to analytes we propose the possibility to use the graphene/SiC Schottky diode as a sensing platform for the recognition of toxic heavy metals. Using density functional theory (DFT) calculations we gain insight into the nature of the interaction of cadmium, mercury and lead with graphene as well as estimate the work function and the Schottky barrier height of the graphene/SiC structure before and after applying heavy metals to the sensing material. A shift of the I-V characteristics of the graphene/SiC-based sensor has been proposed as an indicator of presence of the heavy metals. Since the calculations suggested the strongest charge transfer between Pb and graphene, the proposed sensing platform was characterized by good selectivity towards lead atoms and slight interferences from cadmium and mercury. The dependence of the sensitivity parameters on the concentration of Cd, Hg and Pb is studied and discussed.

  13. Monolayer graphene/SiC Schottky barrier diodes with improved barrier height uniformity as a sensing platform for the detection of heavy metals

    Directory of Open Access Journals (Sweden)

    Ivan Shtepliuk

    2016-11-01

    Full Text Available A vertical diode structure comprising homogeneous monolayer epitaxial graphene on silicon carbide is fabricated by thermal decomposition of a Si-face 4H-SiC wafer in argon atmosphere. Current–voltage characteristics of the graphene/SiC Schottky junction were analyzed by applying the thermionic-emission theory. Extracted values of the Schottky barrier height and the ideality factor are found to be 0.4879 ± 0.013 eV and 1.01803 ± 0.0049, respectively. Deviations of these parameters from average values are smaller than those of previously observed literature data, thereby implying uniformity of the Schottky barrier height over the whole diode area, a stable rectifying behaviour and a good quality of ohmic palladium–graphene contacts. Keeping in mind the strong sensitivity of graphene to analytes we propose the possibility to use the graphene/SiC Schottky diode as a sensing platform for the recognition of toxic heavy metals. Using density functional theory (DFT calculations we gain insight into the nature of the interaction of cadmium, mercury and lead with graphene as well as estimate the work function and the Schottky barrier height of the graphene/SiC structure before and after applying heavy metals to the sensing material. A shift of the I–V characteristics of the graphene/SiC-based sensor has been proposed as an indicator of presence of the heavy metals. Since the calculations suggested the strongest charge transfer between Pb and graphene, the proposed sensing platform was characterized by good selectivity towards lead atoms and slight interferences from cadmium and mercury. The dependence of the sensitivity parameters on the concentration of Cd, Hg and Pb is studied and discussed.

  14. Alloyed 2D Metal-Semiconductor Heterojunctions: Origin of Interface States Reduction and Schottky Barrier Lowering.

    Science.gov (United States)

    Kim, Yonghun; Kim, Ah Ra; Yang, Jin Ho; Chang, Kyoung Eun; Kwon, Jung-Dae; Choi, Sun Young; Park, Jucheol; Lee, Kang Eun; Kim, Dong-Ho; Choi, Sung Mook; Lee, Kyu Hwan; Lee, Byoung Hun; Hahm, Myung Gwan; Cho, Byungjin

    2016-09-14

    The long-term stability and superior device reliability through the use of delicately designed metal contacts with two-dimensional (2D) atomic-scale semiconductors are considered one of the critical issues related to practical 2D-based electronic components. Here, we investigate the origin of the improved contact properties of alloyed 2D metal-semiconductor heterojunctions. 2D WSe2-based transistors with mixed transition layers containing van der Waals (M-vdW, NbSe2/WxNb1-xSe2/WSe2) junctions realize atomically sharp interfaces, exhibiting long hot-carrier lifetimes of approximately 75,296 s (78 times longer than that of metal-semiconductor, Pd/WSe2 junctions). Such dramatic lifetime enhancement in M-vdW-junctioned devices is attributed to the synergistic effects arising from the significant reduction in the number of defects and the Schottky barrier lowering at the interface. Formation of a controllable mixed-composition alloyed layer on the 2D active channel would be a breakthrough approach to maximize the electrical reliability of 2D nanomaterial-based electronic applications.

  15. Tuning a Schottky barrier of epitaxial graphene/4H-SiC (0001) by hydrogen intercalation

    Energy Technology Data Exchange (ETDEWEB)

    Dharmaraj, P.; Justin Jesuraj, P.; Jeganathan, K., E-mail: kjeganathan@yahoo.com [Centre for Nanoscience and Nanotechnology, School of Physics, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu (India)

    2016-02-01

    We report the electron transport properties of epitaxial graphene (EG) grown on 4H-SiC (0001) by low energy electron-beam irradiation. As-grown EG (AEG) on SiC interface exhibits rectifying current-voltage characteristics with a low Schottky barrier (SB) of 0.55 ± 0.05 eV and high reverse current leakage. The SB of AEG/SiC junction is extremely impeded by the Fermi level pinning (FLP) above the Dirac point due to charged states at the interface. Nevertheless, a gentle hydrogen intercalation at 900 °C enables the alleviation of both FLP and carrier scattering owing to the saturation of dangling bonds as evidenced by the enhancement of SB (0.75 ± 0.05 eV) and high electron mobility well excess of 6000 cm{sup 2} V{sup −1} s{sup −1}.

  16. Nanoscale inhomogeneity of the Schottky barrier and resistivity in MoS2 multilayers

    Science.gov (United States)

    Giannazzo, F.; Fisichella, G.; Piazza, A.; Agnello, S.; Roccaforte, F.

    2015-08-01

    Conductive atomic force microscopy (CAFM) is employed to investigate the current injection from a nanometric contact (a Pt coated tip) to the surface of MoS2 thin films. The analysis of local current-voltage characteristics on a large array of tip positions provides high spatial resolution information on the lateral homogeneity of the tip /MoS2 Schottky barrier ΦB and ideality factor n , and on the local resistivity ρloc of the MoS2 region under the tip. Here, ΦB=300 ±24 meV , n =1.60 ±0.23 , and ρloc=2.99 ±0.68 Ω cm are calculated from the distributions of locally measured values. A linear correlation is found between the ρloc and ΦB values at each tip position, indicating a similar origin of the ρloc and ΦB inhomogeneities. These findings are compared with recent literature results on the role of sulfur vacancy clusters on the MoS2 surface as preferential paths for current injection from metal contacts. Furthermore, their implications on the behavior of MoS2 based transistors are discussed.

  17. Enhanced efficiency of Schottky-barrier solar cell with periodically nonhomogeneous indium gallium nitride layer

    Science.gov (United States)

    Anderson, Tom H.; Mackay, Tom G.; Lakhtakia, Akhlesh

    2017-01-01

    A two-dimensional finite-element model was developed to simulate the optoelectronic performance of a Schottky-barrier solar cell. The heart of this solar cell is a junction between a metal and a layer of n-doped indium gallium nitride (InξGaN) alloy sandwiched between a reflection-reducing front window and a periodically corrugated metallic back reflector. The bandgap of the InξGaN layer was varied periodically in the thickness direction by varying the parameter ξ∈(0,1). First, the frequency-domain Maxwell postulates were solved to determine the spatial profile of photon absorption and, thus, the generation of electron-hole pairs. The AM1.5G solar spectrum was taken to represent the incident solar flux. Next, the drift-diffusion equations were solved for the steady-state electron and hole densities. Numerical results indicate that a corrugated back reflector of a period of 600 nm is optimal for photon absorption when the InξGaN layer is homogeneous. The efficiency of a solar cell with a periodically nonhomogeneous InξGaN layer may be higher by as much as 26.8% compared to the analogous solar cell with a homogeneous InξGaN layer.

  18. Surface Passivation of Ti/4H-SiC Schottky Barrier Diode

    Institute of Scientific and Technical Information of China (English)

    Muhammad Khalid; Saira Riaz; Shahzad Naseem

    2012-01-01

    Surface properties of SiC power devices mostly depend on the passivation layer (PL).This layer has direct influence on electrical characteristics of devices.2D numerical simulation of forward and reverse characteristics with and without different (PLs) (SiO2,HfO2 and Si3N4) has been performed.Simulation results show that the breakdown voltage increases with increasing PL thickness,and there is a lesser significant effect on forward characteristics.The maximum breakdown voltage with and without SiO2 PL is 1240 V and 276 V,respectively.SiO2 PL has compatibility with SiC surface providing high breakdown voltage,6 and 8% higher than that of HfO2 and Si3N4 respectively.Low leakage current is observed which then further decreases on reducing the thickness of PL.Furthermore,variation of forward current with dielectric constant and thickness of PLs was observed.Finally,it is suggested that matches of our results with published experimental results indicate that the Sentaurus TCAD simulator is a predictive tool for the SiC Schottky barrier diode simulation.

  19. Microscopic analysis of electron noise in GaAs Schottky barrier diodes

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, T.; Pardo, D. [Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Salamanca, Plaza de la Merced s/n, 37008 Salamanca (Spain); Reggiani, L. [Istituto Nazionale di Fisica della Materia, Dipartimento di Scienza dei Materiali, Universita di Lecce, Via Arnesano, 73100 Lecce (Italy); Varani, L. [Centre dElectronique et de Micro-Optoelectronique de Montpellier (CNRS UMR 5507), Universite Montpellier II, F-34095 Montpellier Cedex 5 (France)

    1997-09-01

    A microscopic analysis of current and voltage fluctuations in GaAs Schottky barrier diodes under forward-bias conditions in the absence of 1/f contributions is presented. Calculations are performed by coupling self-consistently an ensemble Monte Carlo simulator with a one-dimensional Poisson solver. By using current- and voltage-operation modes the microscopic origin and the spatial location of the noise sources, respectively, is provided. At different voltages the device exhibits different types of noise (shot, thermal, and excess), which are explained as a result of the coupling between fluctuations in carrier velocity and self-consistent field. The essential role of the field fluctuations to correctly determine the noise properties in these diodes is demonstrated. The results obtained for the equivalent noise temperature are found to reproduce the typical behavior of experimental measurements. An equivalent circuit is proposed to predict and explain the noise spectra of the device under thermionic emission-based operation. {copyright} {ital 1997 American Institute of Physics.}

  20. Schottky barrier modulation of metal/4H-SiC junction with thin interface spacer driven by surface polarization charge on 4H-SiC substrate

    Science.gov (United States)

    Choi, Gahyun; Yoon, Hoon Hahn; Jung, Sungchul; Jeon, Youngeun; Lee, Jung Yong; Bahng, Wook; Park, Kibog

    2015-12-01

    The Au/Ni/Al2O3/4H-SiC junction with the Al2O3 film as a thin spacer layer was found to show the electrical characteristics of a typical rectifying Schottky contact, which is considered to be due to the leakiness of the spacer layer. The Schottky barrier of the junction was measured to be higher than an Au/Ni/4H-SiC junction with no spacer layer. It is believed that the negative surface bound charge originating from the spontaneous polarization of 4H-SiC causes the Schottky barrier increase. The use of a thin spacer layer can be an efficient experimental method to modulate Schottky barriers of metal/4H-SiC junctions.

  1. Electrical Characteristics of Co/n-Si Schottky Barrier Diodes Using I-V and C-V Measurements

    Institute of Scientific and Technical Information of China (English)

    G.Gfüler; (O).Güllü; (S).Karata(s); (O).F.Bakkalo(g)lu

    2009-01-01

    Electrical characteristics of Co/n-Si Schottky barrier diodes are analysed by current-voltage (I- V) and capacitancevoltage (C-V) techniques at room temperature.The electronic parameters such as ideality factor,barrier height and average series resistance are determined.The barrier height 0.76 eV obtained from the C-V measurements is higher than that of the value 0.70 eV obtained from the I-V measurements.The series resistance Rs and the ideality factor n are determined from the d ln( I ) / dV plot and are found to be 193.62Ω and 1.34,respectively.The barrier height and the Rs value are calculated from the H(I) - I plot and are found to be 0.71 eV and 205.95Ω.Furthermore,the energy distribution of the interface state density is determined from the forward bias I-V characteristics by taking into account the bias dependence of the effective barrier height.The interface state density Nss ranges from 6.484×1011 cm-2eV-1 in (Ec-0.446) eV to 2.801×1010 cm-2eV-1 in (Ec-0.631) eV,of the Co/n-Si Schottky barrier diode.The results show the presence of a thin interracial layer between the metal and the semiconductor.

  2. Study of barrier inhomogeneities using I–V–T characteristics of Mo/4H–SiC Schottky diode

    Energy Technology Data Exchange (ETDEWEB)

    Ouennoughi, Z. [Laboratoire optoélectronique et composants, Department of Physics, Sétif (Algeria); Toumi, S., E-mail: sihem.toumi@gmail.com [Laboratoire optoélectronique et composants, Department of Physics, Sétif (Algeria); Weiss, R. [FIIS, Schottkystrasse 10, 91058 Erlangen (Germany)

    2015-01-01

    In the present work we investigate the forward current–voltage (I–V) characteristics, over a wide temperature range 298–498 K, of Mo/4H–SiC Schottky diode for which aluminum ion implantation was used to create the high resistivity layer forming the guard ring. The (I–V) analysis based on Thermionic Emission (TE) theory shows a decrease of the barrier height ϕ{sub B} and an increase of the ideality factor n when the temperature decreases. These anomalies are mainly due to the barrier height inhomogeneities at the metal/semiconductor interface as we get a Gaussian distribution of the barrier heights when we plot the apparent barrier height ϕ{sub ap} versus q/2kT. The mean barrier height and the standard deviation obtained values are ϕ{sup ¯}{sub B0}=1.160 eV and σ{sub 0}=88.049 mV, respectively. However, by means of the modified Richardson plot Ln(I{sub s}/T{sup 2})−(q{sup 2}σ{sub 0}{sup 2}/2k{sup 2}T{sup 2}) versus q/kT, the mean barrier height and the Richardson constant values obtained are ϕ{sup ¯}{sub B0}=1.139 eV and A{sup *}=129.425 A/cm{sup 2} K{sup 2}, respectively. The latter value of ϕ{sup ¯}{sub B0} matches very well with the mean barrier height obtained from the plot of ϕ{sub ap} versus q/2kT. The Richardson constant is much closer to the theoretical value of 146 A/cm{sup 2} K{sup 2}. The series resistance R{sub s} is also estimated from the forward current–voltage characteristics of Mo/4H–SiC Schottky contact. This parameter shows strong temperature dependence. The T{sub 0} effect is validated for the 298–498 K temperature range for the used Schottky diode and provides a clear evidence for the barrier inhomogeneity at the Mo/4H–SiC interface. Finally, we note the impact of the implantation process as well as the choice of the used ion on the characterized parameters of the Schottky contact.

  3. Study of barrier inhomogeneities using I-V-T characteristics of Mo/4H-SiC Schottky diode

    Science.gov (United States)

    Ouennoughi, Z.; Toumi, S.; Weiss, R.

    2015-01-01

    In the present work we investigate the forward current-voltage (I-V) characteristics, over a wide temperature range 298-498 K, of Mo/4H-SiC Schottky diode for which aluminum ion implantation was used to create the high resistivity layer forming the guard ring. The (I-V) analysis based on Thermionic Emission (TE) theory shows a decrease of the barrier height ϕB and an increase of the ideality factor n when the temperature decreases. These anomalies are mainly due to the barrier height inhomogeneities at the metal/semiconductor interface as we get a Gaussian distribution of the barrier heights when we plot the apparent barrier height ϕap versus q/2kT. The mean barrier height and the standard deviation obtained values are ϕbarB0=1.160 eV and σ0=88.049 mV, respectively. However, by means of the modified Richardson plot Ln (Is /T2) - (q2 σ 0 2 / 2k2T2) versus q/kT, the mean barrier height and the Richardson constant values obtained are ϕbarB0=1.139 eV and A*=129.425 A/cm2 K2, respectively. The latter value of ϕbarB0 matches very well with the mean barrier height obtained from the plot of ϕap versus q/2kT. The Richardson constant is much closer to the theoretical value of 146 A/cm2 K2. The series resistance Rs is also estimated from the forward current-voltage characteristics of Mo/4H-SiC Schottky contact. This parameter shows strong temperature dependence. The T0 effect is validated for the 298-498 K temperature range for the used Schottky diode and provides a clear evidence for the barrier inhomogeneity at the Mo/4H-SiC interface. Finally, we note the impact of the implantation process as well as the choice of the used ion on the characterized parameters of the Schottky contact.

  4. 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.

  5. Theoretical investigation of silicide Schottky barrier detector integrated in horizontal metal-insulator-silicon-insulator-metal nanoplasmonic slot waveguide.

    Science.gov (United States)

    Zhu, Shiyang; Lo, G Q; Kwong, D L

    2011-08-15

    An ultracompact integrated silicide Schottky barrier detector (SBD) is designed and theoretically investigated to electrically detect the surface plasmon polariton (SPP) propagating along horizontal metal-insulator-silicon-insulator-metal nanoplasmonic slot waveguides at the telecommunication wavelength of 1550 nm. An ultrathin silicide layer inserted between the silicon core and the insulator, which can be fabricated precisely using the well-developed self-aligned silicide process, absorbs the SPP power effectively if a suitable silicide is chosen. Moreover, the Schottky barrier height in the silicide-silicon-silicide configuration can be tuned substantially by the external voltage through the Schottky effect owing to the very narrow silicon core. For a TaSi(2) detector with optimized dimensions, numerical simulation predicts responsivity of ~0.07 A/W, speed of ~60 GHz, dark current of ~66 nA at room temperature, and minimum detectable power of ~-29 dBm. The design also suggests that the device's size can be reduced and the overall performances will be further improved if a silicide with smaller permittivity is used.

  6. High energy electron radiation effect on Ni and Ti/4H-SiC Schottky barrier diodes at room temperature

    Institute of Scientific and Technical Information of China (English)

    Zhang Lin; Zhang Yi-Men; Zhang Yu-Ming; Han Chao; Ma Yong-Ji

    2009-01-01

    This paper reports that Ni and Ti/4H-SiC Schottky barrier diodes (SBDs) were fabricated and irradiated with 1 MeV electrons up to a dose of 3.43×1014 e/cm2. After radiation, the Schottky barrier height φB of the Ni/4H-SiC SBD increased from 1.20 eV to 1.21 eV, but decreased from 0.95 eV to 0.94 eV for the Ti/4H-SiC SBD. The degradation of φB could be explained by interface states of changed Schottky contacts. The on-state resistance RS of both diodes increased with the dose, which can be ascribed to the radiation defects. The reverse current of the Ni/4H-SiC SBD slightly increased, but for the Ti/4H-SiC SBD it basically remained the same. At room temperature, φB of the diodes recovered completely after one week, and the RS partly recovered.

  7. High-performance 4H-SiC junction barrier Schottky diodes with double resistive termination extensions

    Science.gov (United States)

    Zheng, Liu; Zhang, Feng; Liu, Sheng-Bei; Dong, Lin; Liu, Xing-Fang; Fan, Zhong-Chao; Liu, Bin; Yan, Guo-Guo; Wang, Lei; Zhao, Wan-Shun; Sun, Guo-Sheng; He, Zhi; Yang, Fu-Hua

    2013-09-01

    4H-SiC junction barrier Schottky (JBS) diodes with a high-temperature annealed resistive termination extension (HARTE) are designed, fabricated and characterized in this work. The differential specific on-state resistance of the device is as low as 3.64 mΩ·cm2 with a total active area of 2.46 × 10-3 cm2. Ti is the Schottky contact metal with a Schottky barrier height of 1.08 V and a low onset voltage of 0.7 V. The ideality factor is calculated to be 1.06. Al implantation annealing is performed at 1250°C in Ar, while good reverse characteristics are achieved. The maximum breakdown voltage is 1000 V with a leakage current of 9 × 10-5 A on chip level. These experimental results show good consistence with the simulation results and demonstrate that high-performance 4H-SiC JBS diodes can be obtained based on the double HARTE structure.

  8. High-performance room-temperature hydrogen sensors based on combined effects of Pd decoration and Schottky barriers

    Science.gov (United States)

    Liu, Bin; Cai, Daoping; Liu, Yuan; Li, Han; Weng, Chao; Zeng, Guoshi; Li, Qiuhong; Wang, Taihong

    2013-02-01

    A new hydrogen sensor was fabricated by coating a Pd-decorated In2O3 film on Au electrodes. In response to 1 vol% H2 at room temperature, an ultra high sensitivity of 4.6 × 107 was achieved. But after an annealing treatment in vacuum, its sensitivity degenerated by 4 orders of magnitude. In addition, the response time and recovery time were also extended from 28 s and 32 s to 242 s and 108 s, respectively. It was found from contrast experiments that Pd decoration was essential to make the sensor work at room temperature and Schottky barriers played a vital role in enhancing the sensor's performance. The methodology demonstrated in this paper shows that a combination of novel sensing materials and Schottky contact is an effective approach to design high-performance gas sensors.A new hydrogen sensor was fabricated by coating a Pd-decorated In2O3 film on Au electrodes. In response to 1 vol% H2 at room temperature, an ultra high sensitivity of 4.6 × 107 was achieved. But after an annealing treatment in vacuum, its sensitivity degenerated by 4 orders of magnitude. In addition, the response time and recovery time were also extended from 28 s and 32 s to 242 s and 108 s, respectively. It was found from contrast experiments that Pd decoration was essential to make the sensor work at room temperature and Schottky barriers played a vital role in enhancing the sensor's performance. The methodology demonstrated in this paper shows that a combination of novel sensing materials and Schottky contact is an effective approach to design high-performance gas sensors. Electronic supplementary information (ESI) available: Hydrogen sensing test details and detailed material characterizations before and after the annealing treatment at 120 °C. See DOI: 10.1039/c3nr33872j

  9. A Study of the Parasitic Properties of the Schottky Barrier Diode

    Science.gov (United States)

    Ren, Tianhao; Zhang, Yong; Liu, Shuang; Guo, Fangzhou; Jin, Zhi; Zhou, Jingtao; Yang, Chengyue

    2016-09-01

    In this paper, we present a newly designed parameter extraction method of the Schottky barrier diode (SBD) with the purpose of measuring and studying its parasitic properties. This method includes three kinds of auxiliary configurations and is named as three-configuration parameter extraction method (TPEM). TPEM has such features as simplicity of operation, self-consistence, and accuracy. With TPEM, the accurate parasitic parameters of the diode can be easily obtained. Taking a GaAs SBD as an example, the pad-to-pad capacitance is 7 fF, the air-bridge finger self-inductance 11 pH, the air-bridge finger self-resistance 0.6 Ω, and the finger-to-pad capacitance 2.1 fF. A more accurate approach to finding the value of the series resistant of the SBD is also proposed, and then a complete SBD model is built. The evaluation of the modeling technology, as well as TPEM, is implemented by comparing the simulated and measured I-V curves and the S-parameters. And good agreements are observed. By using TPEM, the influence of the variation of the geometric parameters is studied, and several ways to reduce the parasitic effect are presented. The results show that the width of the air-bridge finger and the length of the channel are the two largest influencing parameters, with the normalized impact factors 0.56 and 0.29, respectively. By using TPEM and the modeling technology presented in this paper, a design process of the SBD is proposed. As an example, a type of SBD suitable for 500-600 GHz zero-biased detection is designed, and the agreement between the simulated and measured results has been improved. SBDs for other applications could be designed in a similar way.

  10. A Study of the Parasitic Properties of the Schottky Barrier Diode

    Science.gov (United States)

    Ren, Tianhao; Zhang, Yong; Liu, Shuang; Guo, Fangzhou; Jin, Zhi; Zhou, Jingtao; Yang, Chengyue

    2017-02-01

    In this paper, we present a newly designed parameter extraction method of the Schottky barrier diode (SBD) with the purpose of measuring and studying its parasitic properties. This method includes three kinds of auxiliary configurations and is named as three-configuration parameter extraction method (TPEM). TPEM has such features as simplicity of operation, self-consistence, and accuracy. With TPEM, the accurate parasitic parameters of the diode can be easily obtained. Taking a GaAs SBD as an example, the pad-to-pad capacitance is 7 fF, the air-bridge finger self-inductance 11 pH, the air-bridge finger self-resistance 0.6 Ω, and the finger-to-pad capacitance 2.1 fF. A more accurate approach to finding the value of the series resistant of the SBD is also proposed, and then a complete SBD model is built. The evaluation of the modeling technology, as well as TPEM, is implemented by comparing the simulated and measured I-V curves and the S-parameters. And good agreements are observed. By using TPEM, the influence of the variation of the geometric parameters is studied, and several ways to reduce the parasitic effect are presented. The results show that the width of the air-bridge finger and the length of the channel are the two largest influencing parameters, with the normalized impact factors 0.56 and 0.29, respectively. By using TPEM and the modeling technology presented in this paper, a design process of the SBD is proposed. As an example, a type of SBD suitable for 500-600 GHz zero-biased detection is designed, and the agreement between the simulated and measured results has been improved. SBDs for other applications could be designed in a similar way.

  11. The barrier-height inhomogeneity in identically prepared Ni/n-type 6H-SiC Schottky diodes

    Science.gov (United States)

    Duman, S.; Dogan, S.; Gürbulak, B.; Türüt, A.

    2008-05-01

    The effective barrier heights and ideality factors of identically fabricated Ni/n-type 6 H-SiC Schottky diodes (23 dots) have been calculated from their experimental forward bias current voltage (I V) and reverse bias capacitance voltage (C V) characteristics. A statistical study related to the experimental barrier heights (BHs) and ideality factors of the diodes has been made. The effective Schottky barrier heights (SBHs) and ideality factors obtained from the I V and C V characteristics have differed from diode to diode. The BHs obtained from the I V characteristics varied from 0.85 to 1.03 eV, the ideality factors varied from 1.13 to 1.40 and the BHs from C-2 V characteristics varied from 1.10 to 1.70 eV. The experimental BH and ideality factor distributions obtained from the I V characteristics are fitted by a Gaussian function, and their mean values are found to be 0.92±0.04 eV and 1.29±0.08 eV, respectively. The lateral homogeneous SBH value of 1.16 eV for the Ni/n-type 6H-SiC diodes has been calculated from a linear extrapolation of the effective barrier heights to nif=1.03.

  12. Investigation of Current-Voltage Characteristics of Ni/GaN Schottky Barrier Diodes for Potential HEMT Applications

    Directory of Open Access Journals (Sweden)

    Ashish Kumar

    2011-01-01

    Full Text Available In the present work, the I-V characteristics of Ni/GaN Schottky diodes have been studied. The Schottky diodes, having different sizes using Ni/Au and ohmic contacts using Ti/Al/Ni/Au were made on n-GaN. The GaN was epitaxially grown on c-plane sapphire by metal organic chemical vapor deposition (MOCVD technique and had a thickness of about 3.7 µm. The calculated ideality factor and barrier height from current-voltage (I-V characteristics (at 300 K for two GaN Schottky diodes were close to ~1.3 and ~ 0.8 eV respectively. A high reverse leakage current in the order of 10 – 4A/cm2 (at – 1 V was observed in both diodes. A careful analysis of forward bias I-V characteristics showed very high series resistance and calculation for ideality factor indicated presence of other current transport mechanism apart from thermionic model at room temperature.

  13. Electron Excess Doping and Effective Schottky Barrier Reduction on the MoS2/h-BN Heterostructure.

    Science.gov (United States)

    Joo, Min-Kyu; Moon, Byoung Hee; Ji, Hyunjin; Han, Gang Hee; Kim, Hyun; Lee, Gwanmu; Lim, Seong Chu; Suh, Dongseok; Lee, Young Hee

    2016-10-12

    Layered hexagonal boron nitride (h-BN) thin film is a dielectric that surpasses carrier mobility by reducing charge scattering with silicon oxide in diverse electronics formed with graphene and transition metal dichalcogenides. However, the h-BN effect on electron doping concentration and Schottky barrier is little known. Here, we report that use of h-BN thin film as a substrate for monolayer MoS2 can induce ∼6.5 × 10(11) cm(-2) electron doping at room temperature which was determined using theoretical flat band model and interface trap density. The saturated excess electron concentration of MoS2 on h-BN was found to be ∼5 × 10(13) cm(-2) at high temperature and was significantly reduced at low temperature. Further, the inserted h-BN enables us to reduce the Coulombic charge scattering in MoS2/h-BN and lower the effective Schottky barrier height by a factor of 3, which gives rise to four times enhanced the field-effect carrier mobility and an emergence of metal-insulator transition at a much lower charge density of ∼1.0 × 10(12) cm(-2) (T = 25 K). The reduced effective Schottky barrier height in MoS2/h-BN is attributed to the decreased effective work function of MoS2 arisen from h-BN induced n-doping and the reduced effective metal work function due to dipole moments originated from fixed charges in SiO2.

  14. GaN Schottky diodes with single-crystal aluminum barriers grown by plasma-assisted molecular beam epitaxy

    Science.gov (United States)

    Tseng, H. Y.; Yang, W. C.; Lee, P. Y.; Lin, C. W.; Cheng, Kai-Yuan; Hsieh, K. C.; Cheng, K. Y.; Hsu, C.-H.

    2016-08-01

    GaN-based Schottky barrier diodes (SBDs) with single-crystal Al barriers grown by plasma-assisted molecular beam epitaxy are fabricated. Examined using in-situ reflection high-energy electron diffractions, ex-situ high-resolution x-ray diffractions, and high-resolution transmission electron microscopy, it is determined that epitaxial Al grows with its [111] axis coincident with the [0001] axis of the GaN substrate without rotation. In fabricated SBDs, a 0.2 V barrier height enhancement and 2 orders of magnitude reduction in leakage current are observed in single crystal Al/GaN SBDs compared to conventional thermal deposited Al/GaN SBDs. The strain induced piezoelectric field is determined to be the major source of the observed device performance enhancements.

  15. Relationship between crystal defects and leakage current in β-Ga2O3 Schottky barrier diodes

    Science.gov (United States)

    Kasu, Makoto; Hanada, Kenji; Moribayashi, Tomoya; Hashiguchi, Akihiro; Oshima, Takayoshi; Oishi, Toshiyuki; Koshi, Kimiyoshi; Sasaki, Kohei; Kuramata, Akito; Ueda, Osamu

    2016-12-01

    We fabricated Schottky barrier diodes (SBDs) on the entire surface of a (0\\bar{1}0) β-Ga2O3 single crystal, and investigated the leakage current in both forward and reverse directions. Subsequently, we investigated the distribution of dislocation and void etch pits on the entire surface. The dislocation etch pit density on the surface ranged from void etch pit density on the surface ranged from void etch pit densities, we found that dislocations are closely related to the SBD reverse leakage current, and that not all voids produce the leakage current.

  16. Schottky-Like Photodetectors Using Narrow-Gap Semiconductor/silicon Interfaces

    Science.gov (United States)

    Scott, Gregory Stuart

    Infrared focal plane arrays utilizing PtSi/p-Si Schottky barriers have several advantages over narrow-gap semiconductors in the areas of uniformity, ease of manufacture, and potential for integration into monolithic circuits. However, these devices suffer from low quantum efficiency, as the high density of states near the Fermi level of the PtSi limits the efficiency of the optical absorption and hot carrier transport processes. Low transmission from the silicide to the silicon substrate also restricts the photoyield. This thesis presents a novel device concept for infrared detectors which utilizes a thin film of narrow -gap semiconductor deposited on a p-type silicon substrate. The operation of the device would be similar to a Schottky barrier detector, in that carriers would be excited from the overlayer into the substrate. However, the presence of the bandgap in the overlayer should reduce the high density of undesired states near the Fermi level. This would lead to a considerably higher absorption and transport efficiency. The transmission from the overlayer to the substrate should also be greatly increased. Calculations using a diffusion model adapted from one developed by Mercer and Helms for the behavior of Schottky barrier detectors indicate the potential for more than an order of magnitude improvement in quantum efficiency over present technology at a wavelength of 4 mum. The experimental work involved structures formed with films that are easily prepared by thermal evaporation, namely PbTe, SnTe, and Pb_{rm 1-x}Sn_{rm x} Te. Materials analysis showed that stoichiometric, highly oriented polycrystalline films were deposited. The SnTe/p-Si and Pb_{rm 1-x} Sn_{rm x}Te/p -Si devices exhibited Schottky-like behavior, while PbTe/p -Si diodes behaved as photoconductors in weak electrical contact to the substrate. The photoresponse did not display the expected increase in quantum efficiency over Schottky barriers, and investigation of the device electrical

  17. Performance Improvement of GaN Based Schottky Barrier Ultraviolet Photodetector by Adding a Thin AlGaN Window Layer

    Institute of Scientific and Technical Information of China (English)

    ZHOU Mei; ZHAO De-Gang

    2007-01-01

    We propose a new structure of GaN based Schottky barrier ultraviolet photodetector, in which a thin n-type AlGaN window layer is added on the conventional n--GaN/n+-GaN device structure. The performance of the Schottky barrier ultraviolet photodetector is found to be improved by the new structure. The simulation result shows that the new structure can reduce the negative effect of surface states on the performance of Schottky barrier GaN photodetectors, improving the quantum efficiency and decreasing the dark current. The investigations suggest that the new photodetector can exhibit a better responsivity by choosing a suitably high carrier concentration and thin thickness for the AlGaN window layer.

  18. Barrier height of Pt–In[sub x]Ga[sub 1−x]N (0≤x≤0.5) nanowire Schottky diodes

    KAUST Repository

    Guo, Wei

    2011-01-01

    The barrier height of Schottky diodes made on Inx Ga 1-x N nanowires have been determined from capacitance-voltage measurements. The nanowires were grown undoped on n-type (001) silicon substrates by plasma-assisted molecular beam epitaxy. The length, diameter and density of the nanowires are ∼1 μm, 20 nm, and 1× 1011 cm-2. The Schottky contact was made on the top surface of the nanowires with Pt after planarizing with parylene. The measured barrier height B varies from 1.4 eV (GaN) to 0.44 eV (In0.5 Ga0.5 N) and agrees well with the ideal barrier heights in the Schottky limit. © 2011 American Institute of Physics.

  19. Theory of potential distributions in abrupt heterojunction crystalline semiconductor devices: Treatment of Schottky barriers and rectifiers

    Science.gov (United States)

    Mohammad, S. Noor

    1988-03-01

    present formulas a general form for potential distribution in Schottky barriers has been derived. The relation reduces to that of Gummel and Scarfetter [J. Appl. Phys. 38, 2148 (1967)] under special conditions. Theoretical reasons underlying the lack of rectification in various n-N HJs have been analyzed. In light of this analysis, a theoretical model in terms of many-body electron-electron and electron-donor interactions, and in terms of lowering of band edge in the vicinity of transition region, has been proposed. Numerical results obtained from this model for n-GaAs agree remarkably with observations from experimental measurements.

  20. Band structure, band offsets, substitutional doping, and Schottky barriers of bulk and monolayer InSe

    Science.gov (United States)

    Guo, Yuzheng; Robertson, John

    2017-09-01

    We present a detailed study of the electronic structure of the layered semiconductor InSe. We calculate the band structure of the monolayer and bulk material using density functional theory, hybrid functionals, and G W . The band gap of the monolayer InSe is calculated to be 2.4 eV in screened exchange hybrid functional, close to the experimental photoluminescence gap. The electron affinities and band offsets are calculated for vertical stacked-layer heterostructures, and are found to be suitable for tunnel field effect transistors (TFETs) in combination with WS e2 or similar. The valence-band edge of InSe is calculated to lie 5.2 eV below the vacuum level, similar to that for the closed shell systems HfS e2 or SnS e2 . Hence InSe would be suitable to act as a p -type drain in the TFET. The intrinsic defects are calculated. For Se-rich layers, the Se adatom (interstitial) is found to be the most stable defect, whereas for In-rich layers, the Se vacancy is the most stable for the neutral state. Antisites tend to have energies just above those of vacancies. The Se antisite distorts towards a bond-breaking distortion as in the EL2 center of GaAs. Both substitutional donors and acceptors are calculated to be shallow, and effective dopants. They do not reconstruct to form nondoping configurations as occurs in black phosphorus. Finally, the Schottky barriers of metals on InSe are found to be strongly pinned by metal induced gap states (MIGS) at ˜0.5 eV above the valence-band edge. Any interfacial defects would lead to a stronger pinning at a similar energy. Overall, InSe is an effective semiconductor combining the good features of 2D (lack of dangling bonds, etc.) with the good features of 3D (effective doping), which few others achieve.

  1. Schottky barrier detectors on 4H-SiC n-type epitaxial layer for alpha particles

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhuri, S.K.; Krishna, R.M.; Zavalla, K.J. [Department of Electrical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Mandal, K.C., E-mail: mandalk@cec.sc.edu [Department of Electrical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

    2013-02-11

    Schottky barrier detectors have been fabricated on 50 μm n-type 4H-SiC epitaxial layers grown on 360 μm SiC substrates by depositing ∼10 nm nickel contact. Current–voltage (I–V) and capacitance–voltage (C–V) measurements were carried out to investigate the Schottky barrier properties. The detectors were evaluated for alpha particle detection using a {sup 241}Am alpha source. An energy resolution of ∼2.7% was obtained with a reverse bias of 100 V for 5.48 MeV alpha particles. The measured charge collection efficiency (CCE) was seen to vary as a function of bias voltage following a minority carrier diffusion model. Using this model, a diffusion length of∼3.5 μm for holes was numerically calculated from the CCE vs. bias voltage plot. Rise-time measurements of digitally recorded charge pulses for the 5.48 MeV alpha particles showed a presence of two sets of events having different rise-times at a higher bias of 200 V. A biparametric correlation scheme was successfully implemented for the first time to visualize the correlated pulse-height distribution of the events with different rise-times. Using the rise-time measurements and the biparametric plots, the observed variation of energy resolution with applied bias was explained.

  2. Schottky barrier height modification of metal/4H-SiC contact using ultrathin TiO2 insertion method

    Science.gov (United States)

    Tsui, Bing-Yue; Cheng, Jung-Chien; Lee, Lurng-Shehng; Lee, Chwan-Ying; Tsai, Ming-Jinn

    2014-01-01

    The fabrication processes, electrical characteristics, and reliability of the Schottky barrier diodes (SBDs) on an n-type 4H-silicon carbide (SiC) substrate are investigated. To modulate the Schottky barrier height (SBH), titanium dioxide (TiO2) is inserted at the interface between the metal and the SiC substrate. Ni, Mo, Ti, and Al are chosen to form SBDs. The maximum SBH modulation of 0.3 eV is obtained with a 5-nm-thick TiO2 layer. The SBH pinning factors of the SBDs without TiO2 insertion and with 2-nm-thick TiO2 insertion are similar. Therefore, the mechanism of the SBH modulation is attributed to the interface dipole-induced potential drop. Finally, the reliability of the SBD with TiO2 insertion is evaluated. The SBH, ideality factor, and reverse leakage current are stable after high forward current stress at 300 A/cm2 for 15000 s. This work provides a simple method to modulate the SBH on SiC and is feasible for SBD application.

  3. Barrier characteristics of Pt/Ru Schottky contacts on -type GaN based on –– and –– measurements

    Indian Academy of Sciences (India)

    N Nanda Kumar Reddy; V Rajagopal Reddy

    2012-02-01

    We have investigated the current–voltage (–) and capacitance–voltage (–) characteristics of Ru/Pt/-GaN Schottky diodes in the temperature range 100–420 K. The calculated values of barrier height and ideality factor for the Ru/Pt/-GaN Schottky diode are 0.73 eV and 1.4 at 420 K, 0.18 eV and 4.2 at 100 K, respectively. The zero-bias barrier height ($\\Phi_{\\text{b}0}$) calculated from – characteristics is found to be increased and the ideality factor () decreased with increasing temperature. Such a behaviour of $\\Phi_{\\text{b}0}$ and n is attributed to Schottky barrier (SB) inhomogeneities by assuming a Gaussian distribution (GD) of barrier heights (BHs) at themetal/semiconductor interface. The current–voltage–temperature (––) characteristics of the Ru/Pt/-GaN Schottky diode have shown a double Gaussian distribution having mean barrier heights ($\\bar{\\Phi}_{\\text{b}0}$) of 1.001 eV and 0.4701 eV and standard deviations ($\\sigma_{0}$) of 0.1491 V and 0.0708 V, respectively. The modified ln($J_{0}/T^{2}$) − ($q^{2}\\sigma^{2}_{0}/2k^{2}T^{2}$) vs 10$^{3}/T$ plot gives $\\bar{\\Phi}_{\\text{b}0}$ and Richardson constant values as 0.99 eV and 0.47 eV, and 27.83 and 10.29 A/cm2K2, respectively without using the temperature coefficient of the barrier height. The difference between the apparent barrier heights (BHs) evaluated from the – and – methods has been attributed to the existence of Schottky barrier height inhomogeneities.

  4. Intermediate type excitons in Schottky barriers of A{sup 3}B{sup 6} layer semiconductors and UV photodetectors

    Energy Technology Data Exchange (ETDEWEB)

    Alekperov, O.Z.; Guseinov, N.M.; Nadjafov, A.I. [Insitute of Physics of National Academy of Sinces of Azerbaijan, H. Javid av. 33, 1133 Baku (Azerbaijan)

    2006-09-15

    Photoelectric and photovoltaic spectra of Schottky barrier (SB) structures of InSe, GaSe and GaS layered semiconductors (LS) are investigated at quantum energies from the band edge excitons of corresponding materials up to 6.5eV. Spectral dependences of photoconductivity (PC) of photo resistors and barrier structures are strongly different at the quantum energies corresponding to the intermediate type excitons (ITE) observed in these semiconductors. It was suggested that high UV photoconductivity of A{sup 3}B{sup 6} LS is due to existence of high mobility light carriers in the depth of the band structure. It is shown that SB of semitransparent Au-InSe is high sensitive photo detector in UV region of spectra. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. DLTS analysis of electron and hole traps in proton implanted VPE grown n-GaAs using Schottky barrier diodes

    Energy Technology Data Exchange (ETDEWEB)

    Auret, F.D.; Nel, M.; Snyman, H.C.

    1988-02-01

    Schottky barrier diodes (SBDs) were used for Deep Level Transient Spectroscopy (DLTS) characterization of electrically active defects in proton implanted n-GaAs. Although SBDs are usually only used for the detection of majority carrier defects (electron traps in n-GaAs), the fabrication of high barrier height SBDs on lowly doped ( less than or equal to 1 x 10/sup 15/cm/sup 3/) n-GaAs in conjunction with a forward bias DLTS filling pulse enabled the detection of minority carrier defects (hole traps in n-GaAs) as well, without using optical excitation. The most prominent electron and hole traps detected had properties that corresponded with those of the well known irradiation-induced electron traps E1-E4 and hole traps H0-H4, associated with the damage produced during high energy particle irradiation.

  6. Schottky barrier height of Ni to β-(AlxGa1‑x)2O3 with different compositions grown by plasma-assisted molecular beam epitaxy

    Science.gov (United States)

    Ahmadi, Elaheh; Oshima, Yuichi; Wu, Feng; Speck, James S.

    2017-03-01

    Coherent β-(AlxGa1‑x)2O3 films (x = 0, 0.038, 0.084, 0.164) were grown successfully on a Sn-doped β-Ga2O3 (010) substrate using plasma-assisted molecular beam epitaxy. Atom probe tomography, transmission electron microscopy, and high resolution x-ray diffraction were used to verify the alloy composition and high quality of the films. Schottky diodes were then fabricated using Ni as the Schottky metal. Capacitance–voltage measurements revealed a very low (current–voltage (I–V) measurements performed at temperatures varying from 300 K to 500 K on the Schottky diodes. These measurements revealed that the apparent Schottky barrier height could have similar values for different compositions of β-(AlxGa1‑x)2O3. We believe this is attributed to the lateral fluctuation in the alloy’s composition. This results in a lateral variation in the barrier height. Therefore, the average Schottky barrier height extracted from I–V measurements could be similar for β-(AlxGa1‑x)2O3 films with different compositions.

  7. Large barrier, highly uniform and reproducible Ni-Si/4H-SiC forward Schottky diode characteristics: testing the limits of Tung's model

    Science.gov (United States)

    Omar, Sabih U.; Sudarshan, Tangali S.; Rana, Tawhid A.; Song, Haizheng; Chandrashekhar, M. V. S.

    2014-07-01

    We report highly ideal (n < 1.1), uniform nickel silicide (Ni-Si)/SiC Schottky barrier (1.60-1.67 eV with a standard deviation <2.8%) diodes, fabricated on 4H-SiC epitaxial layers grown by chemical vapour deposition. The barrier height was constant over a wide epilayer doping range of 1014-1016 cm-3, apart from a slight decrease consistent with image force lowering. This remarkable uniformity was achieved by careful optimization of the annealing of the Schottky interface to minimize non-idealities that could lead to inhomogeneity. Tung's barrier inhomogeneity model was used to quantify the level of inhomogeneity in the optimized annealed diodes. The estimated ‘bulk’ barrier height (1.75 eV) was consistent with the Shockley-Mott limit for the Ni-Si/4H-SiC interface, implying an unpinned Fermi level. But the model was not useful to explain the poor ideality in unoptimized, as-deposited Schottky contacts (n = 1.6 - 2.5). We show analytically and numerically that only idealities n < 1.21 can be explained using Tung's model, irrespective of material system, indicating that the barrier height inhomogeneity is not the only cause of poor ideality in Schottky diodes. For explaining this highly non-ideal behaviour, other factors (e.g. interface traps, morphological defects, extrinsic impurities, etc) need to be considered.

  8. High performance and transparent multilayer MoS2 transistors: Tuning Schottky barrier characteristics

    Directory of Open Access Journals (Sweden)

    Young Ki Hong

    2016-05-01

    Full Text Available Various strategies and mechanisms have been suggested for investigating a Schottky contact behavior in molybdenum disulfide (MoS2 thin-film transistor (TFT, which are still in much debate and controversy. As one of promising breakthrough for transparent electronics with a high device performance, we have realized MoS2 TFTs with source/drain electrodes consisting of transparent bi-layers of a conducting oxide over a thin film of low work function metal. Intercalation of a low work function metal layer, such as aluminum, between MoS2 and transparent source/drain electrodes makes it possible to optimize the Schottky contact characteristics, resulting in about 24-fold and 3 orders of magnitude enhancement of the field-effect mobility and on-off current ratio, respectively, as well as transmittance of 87.4 % in the visible wavelength range.

  9. Effect of thermal treatment on the characteristics of iridium Schottky barrier diodes on n-Ge (1 0 0)

    Energy Technology Data Exchange (ETDEWEB)

    Chawanda, A., E-mail: albert.chawanda@up.ac.za [Department of Physics, University of Pretoria, 0002 (South Africa); Department of Physics, Midlands State University, Bag 9055, Gweru (Zimbabwe); Coelho, S.M.M.; Auret, F.D.; Mtangi, W. [Department of Physics, University of Pretoria, 0002 (South Africa); Nyamhere, C. [Department of Physics, Nelson Mandela Metropolitan University, Box 77000, Port Elizabeth 6031 (South Africa); Nel, J.M.; Diale, M. [Department of Physics, University of Pretoria, 0002 (South Africa)

    2012-02-05

    Highlights: Black-Right-Pointing-Pointer Ir/n-Ge (1 0 0) Schottky diodes were characterized using I-V, C-V and SEM techniques under various annealing conditions. Black-Right-Pointing-Pointer The variation of the electrical and structural properties can be due to effects phase transformation during annealing. Black-Right-Pointing-Pointer Thermal stability of these diodes is maintained up to 500 Degree-Sign C anneal. Black-Right-Pointing-Pointer SEM results depicts that the onset temperature for agglomeration in 20 nm Ir/n-Ge (1 0 0) system occurs between 600 and 700 Degree-Sign C. - Abstract: Iridium (Ir) Schottky barrier diodes were deposited on bulk grown (1 0 0) Sb-doped n-type germanium by using the electron beam deposition system. Electrical characterization of these contacts using current-voltage (I-V) and capacitance-voltage (C-V) measurements was performed under various annealing conditions. The variation of the electrical properties of these Schottky diodes can be attributed to combined effects of interfacial reaction and phase transformation during the annealing process. Thermal stability of the Ir/n-Ge (1 0 0) was observed up to annealing temperature of 500 Degree-Sign C. Furthermore, structural characterization of these samples was performed by using a scanning electron microscopy (SEM) at different annealing temperatures. Results have also revealed that the onset temperature for agglomeration in a 20 nm Ir/n-Ge (1 0 0) system occurs between 600 and 700 Degree-Sign C.

  10. Schottky barrier height of Ni/TiO2/4H-SiC metal-insulator-semiconductor diodes

    Science.gov (United States)

    Kaufmann, Ivan R.; Pereira, Marcelo B.; Boudinov, Henri I.

    2015-12-01

    Ni/TiO2/4H-SiC diodes were analysed through measurements of current-voltage curves varying the temperature. The Schottky Barrier Height (SBH) which increased with temperature was studied by simulation of the Thermionic Emission Model, considering Ni/SiC Schottky structures with an insulator layer between the metal and semiconductor. This model shows that a new method of calculation should be applied to diodes that have a metal-insulator-semiconductor structure. Misleading results for SBH are obtained if the thin insulator layer is not considered. When applying the suggested method to the Ni/TiO2/4H-SiC diodes it was necessary to consider not only the deposited TiO2 layer, but also a second dielectric layer of native SiCxOy at the surface of SiC. By measuring I-V-T curves for two samples with different thicknesses of TiO2, the suggested method allows one to estimate the thicknesses of both dielectric layers: TiO2 and SiOxCy.

  11. Mg doping of InGaN layers grown by PA-MBE for the fabrication of Schottky barrier photodiodes

    Energy Technology Data Exchange (ETDEWEB)

    Pereiro, J; Redondo-Cubero, A; Fernandez-Garrido, S; Rivera, C; Navarro, A; Munoz, E; Calleja, E [Instituto de Sistemas Optoelectronicos y MicrotecnologIa, Universidad Politecnica de Madrid, E-28040 Madrid (Spain); Gago, R, E-mail: jpereiro@die.upm.e [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones CientIficas, E-28049 Madrid (Spain)

    2010-08-25

    This work reports on the fabrication of Schottky barrier based Mg-doped (In,Ga)N layers for fluorescence applications. Mg acceptors are used in order to compensate surface and bulk donors that prevent the fabrication of Schottky contacts on unintentionally doped (In,Ga)N layers grown by plasma-assisted molecular beam epitaxy (PA-MBE). Rectifying properties of the contacts exhibited a major improvement when (In,Ga)N : Mg was used. The electrical and optical measurements of the layers showed a hole concentration of up to 3 x 10{sup 19} holes cm{sup -3} with a Mg acceptor activation energy of {approx}60 meV. Back-illuminated photodiodes fabricated on 800 nm thick Mg-doped In{sub 0.18}Ga{sub 0.82}N layers exhibited a band pass photo-response with a rejection ratio >10{sup 2} between 420 and 470 nm and peak responsivities of 87 mA W{sup -1} at {approx}470 nm. The suitability of these photodiodes for fluorescence measurements was demonstrated.

  12. Modeling of Schottky Barrier Height and Volt-Amper Characteristics for Transition Metal-solid Solution (SіC1 – x(AlNx

    Directory of Open Access Journals (Sweden)

    V.I. Altukhov

    2016-11-01

    Full Text Available Proposed nonlinear defect concentration model of metal-semiconductor contact. It is shown that taking into account nonlinear dependence of the Fermi energy EF defect concentration leads to higher barrier Schottky in 15-25 %. Calculated Volt-Amper characteristics of the diodes are consistent with experiment.

  13. 640 x 480 PtSi infrared engine

    Science.gov (United States)

    Lang, Frank B.; Coyle, Peter J.; Stabile, Paul J.; Tower, John R.; Zubalsky, I.; Ornstein, Itzhak

    1996-06-01

    The design and performance of a compact, light-weight, low power infrared engine is presented. The 3 - 5 micron MWIR imaging subsystem consists of a Stirling-cooled, 640 (H) by 480 (V) staring PtSi infrared focal plane array (IRFPA) with associated drive and analog video processing electronics. The IR engine provides user-selectable integration time control. This infrared imaging subsystem is designed to be gimbal-mounted, and has been qualified to be operated in minus 10 Celsius to plus 50 Celsius environments. The infrared engine is also designed to meet the requirements of demanding shock and vibration environments.

  14. InGaAs Schottky barrier diode array detector for a real-time compact terahertz line scanner.

    Science.gov (United States)

    Han, Sang-Pil; Ko, Hyunsung; Park, Jeong-Woo; Kim, Namje; Yoon, Young-Jong; Shin, Jun-Hwan; Kim, Dae Yong; Lee, Dong Hun; Park, Kyung Hyun

    2013-11-04

    We present a terahertz (THz) broadband antenna-integrated 1 × 20 InGaAs Schottky barrier diode (SBD) array detector with an average responsivity of 98.5 V/W at a frequency of 250 GHz, which is measured without attaching external amplifiers and Si lenses, and an average noise equivalent power (NEP) of 106.6 pW/√Hz. The 3-dB bandwidth of the SBD detector is also investigated at approximately 180 GHz. For implementing an array-type SBD detector by a simple fabrication process to achieve a high yield, a structure comprising an SiN(x) layer instead of an air bridge between the anode and the cathode is designed. THz line beam imaging using a Gunn diode emitter with a center frequency of 250 GHz and a 1 × 20 SBD array detector is successfully demonstrated.

  15. Effect of side-chain length on rectification and photovoltaic characteristics of poly(3-alkylthiophene) Schottky barriers

    Energy Technology Data Exchange (ETDEWEB)

    Fang Yih; Chen Showan (Dept. of Chemical Engineering, National Tsing-Hua Univ., Hsinchu (Taiwan)); Chu, M.L. (Inst. of Electro-Optical Engineering, National Chiao-Tung Univ., Hsinchu (Taiwan))

    1992-10-15

    Schottky diodes of aluminium/poly(3-alkylthiophene) (P3AT)/indium-tin oxide (ITO) with large area (0.15-0.5 cm[sup 2]) are prepared using the proposed new casting technique. The P3ATs investigated involve poly(3-butylthiophene) (P3BT), poly(3-octylthiophene) (P3OT) and poly(3-dodecylthiophene) (P3DDT), which are prepared using the chemical method. The diodes, in which P3AT behaves as a p-type semiconductor, exhibit a moderate rectifying behaviour and low leakage current. Photovoltaic measurements show a power conversion efficiency of about 10[sup -2]-10[sup -3]% at a light intensity of 0.5-5 mW/cm[sup 2], which decreases with increasing light intensity. The longer alkyl side-chain length of P3ATs can cause a lower rectifying effect, barrier height, depletion region width and photovoltaic conversion efficiency. (orig.).

  16. 4H-SiC Schottky barrier diodes with semi-insulating polycrystalline silicon field plate termination

    Science.gov (United States)

    Yuan, Hao; Tang, Xiao-Yan; Zhang, Yi-Men; Zhang, Yu-Ming; Song, Qing-Wen; Yang, Fei; Wu, Hao

    2014-05-01

    Based on the theoretical analysis of the 4H-SiC Schottky-barrier diodes (SBDs) with field plate termination, 4H-SiC SBD with semi-insulating polycrystalline silicon (SIPOS) FP termination has been fabricated. The relative dielectric constant of the SIPOS dielectric first used in 4H-SiC devices is 10.4, which is much higher than that of the SiO2 dielectric, leading to benefitting the performance of devices. The breakdown voltage of the fabricated SBD could reach 1200 V at leakage current 20 μA, about 70% of the theoretical breakdown voltage. Meanwhile, both of the simulation and experimental results show that the length of the SIPOS FP termination is an important factor for structure design.

  17. Van der Waals metal-semiconductor junction: Weak Fermi level pinning enables effective tuning of Schottky barrier.

    Science.gov (United States)

    Liu, Yuanyue; Stradins, Paul; Wei, Su-Huai

    2016-04-01

    Two-dimensional (2D) semiconductors have shown great potential for electronic and optoelectronic applications. However, their development is limited by a large Schottky barrier (SB) at the metal-semiconductor junction (MSJ), which is difficult to tune by using conventional metals because of the effect of strong Fermi level pinning (FLP). We show that this problem can be overcome by using 2D metals, which are bounded with 2D semiconductors through van der Waals (vdW) interactions. This success relies on a weak FLP at the vdW MSJ, which is attributed to the suppression of metal-induced gap states. Consequently, the SB becomes tunable and can vanish with proper 2D metals (for example, H-NbS2). This work not only offers new insights into the fundamental properties of heterojunctions but also uncovers the great potential of 2D metals for device applications.

  18. Rapid thermal annealing effects on the electrical and structural properties of Ru/V/n-InP Schottky barrier diode

    Science.gov (United States)

    Padma, R.; Shanthi Latha, K.; Rajagopal Reddy, V.; Choi, Chel-Jong

    2015-07-01

    A Ru/V/n-InP Schottky barrier diode (SBD) is fabricated and investigated its electrical and structural properties as a function of annealing temperature. Measurements showed that the barrier height (BH) of the as-deposited Ru/V/n-InP SBD is found to be 0.83 eV (I-V) and 1.03 eV (C-V). Experimental results indicate that the SBD with high BH and low ideality factors (0.87 eV (I-V), 1.20 eV (C-V), and 1.12) can be achieved after annealing at 400 °C for 1 min in N2 atmosphere. Further, it is observed that the BH slightly decreases to 0.85 eV (I-V) and 1.09 eV (C-V) upon annealing at 500 °C. The BH, ideality factor and series resistance are also determined by Cheung's functions and Norde method. Further, the energy distribution of interface state density of Ru/V/n-InP SBD is calculated from the forward bias I-V characteristics as a function of annealing temperature. It is found that the interface state density decreases upon annealing at 400 °C and then slightly increases after annealing at 500 °C. The AES and XRD results revealed that the formation of indium phases at the Ru/V/n-InP interface could be the reason for the increase of BH upon annealing at 400 °C. The formation of phosphide phases at the interface may be the cause for the decrease of BH after annealing at 500 °C. The overall surface morphology of Ru/V Schottky contacts is considerably smooth at elevated temperatures.

  19. Analysis of Schottky barrier heights of metal/SiC contacts and its possible application to high-voltage rectifying devices

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, A. [Tokyo Inst. of Technol. (Japan). Dept. of Phys. Electron.; Matsunami, H. [Dept. of Electronic Science and Engineering, Kyoto Univ. (Japan)

    1997-07-16

    Schottky contacts of metal/3C-, 6H-, and 4H-SiC systems are investigated in this review. Most Schottky contacts having large barrier heights show good characteristics with low ideality factors. The barrier height depends on the metal work function without strong Fermi-level pinning for all polytypes, and linear relationships with slopes of about 0.2 to 0.7 are observed between the barrier height and the metal work function. Based on the analysis of metal/SiC systems, the fabrication of high-voltage rectifiers has been reported, and high voltages from 400 to 1100 V have been achieved using Pt/, Ti/, and Au/6H-SiC structures. In addition, high-temperature operation at 400 C is performed for an Au/6H-SiC structure while supporting a high reverse bias (460 V). Using Ti/4H-SiC structures, high-voltage ({approx}1000 V) and low-power loss characteristics are realized, which is superior to Ti/6H-SiC Schottky rectifiers. To improve the reverse bias characteristics, an edge termination technique is employed for Ti/4H-SiC Schottky rectifiers, and the devices show excellent characteristics with a higher blocking voltage up to 1750 V compared with unterminated devices. (orig.) 78 refs.

  20. Electrical parameters and series resistance analysis of Au/Y/p-InP/Pt Schottky barrier diode at room temperature

    Science.gov (United States)

    Rao, L. Dasaradha; Reddy, V. Rajagopal

    2016-05-01

    The current-voltage (I-V) characteristics of Au/Y/p-InP/Pt Schottky barrier diode (SBD) are analyzed at room temperature. The Au/Y/p-InP/Pt SBD shows a good rectification behavior. The ideality factor (n), barrier height (Φb), series resistance (Rs) and shunt resistance (Rsh) are determined from the I-V measurements. The n and Φb values of Au/Y/p-InP/Pt SBD are found to be 1.32 and 0.62 eV respectively. The value of barrier height (BH) obtained from Norde function is compared with those calculated from Cheung's functions. The series resistance (Rs) is calculated from Cheung's and modified Norde functions. Additionally, it is found that n, Φb, Rs, and Rsh have strong correlation with the applied bias. Furthermore, at low and high voltage regions, ohmic and space-charge-limited conduction mechanisms are found to govern the current flow in the diode.

  1. Barrier inhomogeneities and interface states of metal/4H-SiC Schottky contacts

    Science.gov (United States)

    Huang, Lingqin; Geiod, Rechard; Wang, Dejun

    2016-12-01

    The barrier and interface states of Ti, Mo, Ni, and Pt contacts to 4H-SiC were investigated. It is found that the barrier heights for all the contacts are Gaussianly distributed and the barrier inhomogeneity varies with the contact metal type. However, the energy-averaged interface states density in the band gap is metal-insensitive. When considering Gaussian distribution, the interface states density extracted from the electrical properties is consistent with the average density of Gaussianly distributed 4H-SiC surface states, indicating that the barrier inhomogeneities at metal/SiC contacts mainly originate from the spatial variation of surface states on SiC surface. The barrier height and barrier inhomogeneity could be modulated by the contact metal, obeying the barrier height theory of Cowley and Sze.

  2. DLTS detection of hole traps in MBE grown p-GaAs using Schottky barrier diodes

    Energy Technology Data Exchange (ETDEWEB)

    Auret, F.D.; Goodman, S.A.; Myburg, G. (Univ. of Pretoria (South Africa))

    1992-12-01

    The presence of hole traps has been studied by deep level transient spectroscopy (DLTS) characterization of low carrier density p-type GaAs grown by MBE on p[sup +]-GaAs substrates using Al and Co Schottky contacts. The results obtained indicate the presence of several hole traps with energy levels of between 0.06 and 0.65 eV above the valence band in concentrations up to 2 [times] 10[sup 12]/cm[sup 3]. Some of these defects, e.g. Cu, are ascribed to system-, source- or substrate-related impurities, but the origin of several other defects is unknown. 18 refs., 2 figs., 1 tab.

  3. Effect of Annealing Temperature on the Formation of Silicides and the Surface Morphologies of PtSi Films

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effect of annealing temperature on the formation of the PtSi phase, distribution of silicides and the surface morphologies of silicides films is investigated by XPS, AFM. It is shown that the phase sequences of the films change from Pt-Pt2Si-PtSi-Si to Pt+Pt2Si+PtSi-PtSi-Si or Pt+Pt2Si+PtSi-PtSi-Si with an increase of annealing temperature and the reason for the formation of mixed layers is discussed.

  4. Schottky barrier diode based on β-Ga2O3 (100) single crystal substrate and its temperature-dependent electrical characteristics

    Science.gov (United States)

    He, Qiming; Mu, Wenxiang; Dong, Hang; Long, Shibing; Jia, Zhitai; Lv, Hangbing; Liu, Qi; Tang, Minghua; Tao, Xutang; Liu, Ming

    2017-02-01

    The Pt/β-Ga2O3 Schottky barrier diode and its temperature-dependent current-voltage characteristics were investigated for power device application. The edge-defined film-fed growth (EFG) technique was utilized to grow the (100)-oriented β-Ga2O3 single crystal substrate that shows good crystal quality characterized by X-ray diffraction and high resolution transmission electron microscope. Ohmic and Schottky electrodes were fabricated by depositing Ti and Pt metals on the two surfaces, respectively. Through the current-voltage (I-V) measurement under different temperature and the thermionic emission modeling, the fabricated Pt/β-Ga2O3 Schottky diode was found to show good performances at room temperature, including rectification ratio of 1010, ideality factor (n) of 1.1, Schottky barrier height (ΦB) of 1.39 eV, threshold voltage (Vbi) of 1.07 V, ON-resistance (RON) of 12.5 mΩ.cm2, forward current density at 2 V (J@2V) of 56 A/cm2, and saturation current density (J0) of 2 × 10-16 A/cm2. The effective donor concentration Nd - Na was calculated to be about 2.3 × 1014 cm3. Good temperature dependent performance was also found in the device. The Schottky barrier height was estimated to be about 1.3 eV-1.39 eV at temperatures ranging from room temperature to 150 °C. With increasing temperature, parameters such as RON and J@2V become better, proving that the diode can work well at high temperature. The EFG grown β-Ga2O3 single crystal is a promising material to be used in the power devices.

  5. Analytical model of threshold voltage degradation due to localized charges in gate material engineered Schottky barrier cylindrical GAA MOSFETs

    Science.gov (United States)

    Kumar, Manoj; Haldar, Subhasis; Gupta, Mridula; Gupta, R. S.

    2016-10-01

    The threshold voltage degradation due to the hot carrier induced localized charges (LC) is a major reliability concern for nanoscale Schottky barrier (SB) cylindrical gate all around (GAA) metal-oxide-semiconductor field-effect transistors (MOSFETs). The degradation physics of gate material engineered (GME)-SB-GAA MOSFETs due to LC is still unexplored. An explicit threshold voltage degradation model for GME-SB-GAA-MOSFETs with the incorporation of localized charges (N it) is developed. To accurately model the threshold voltage the minimum channel carrier density has been taken into account. The model renders how +/- LC affects the device subthreshold performance. One-dimensional (1D) Poisson’s and 2D Laplace equations have been solved for two different regions (fresh and damaged) with two different gate metal work-functions. LCs are considered at the drain side with low gate metal work-function as N it is more vulnerable towards the drain. For the reduction of carrier mobility degradation, a lightly doped channel has been considered. The proposed model also includes the effect of barrier height lowering at the metal-semiconductor interface. The developed model results have been verified using numerical simulation data obtained by the ATLAS-3D device simulator and excellent agreement is observed between analytical and simulation results.

  6. Valence-band offsets and Schottky barrier heights of layered semiconductors explained by interface-induced gap states

    Science.gov (United States)

    Mönch, Winfried

    1998-04-01

    Many metal chalcogenides are layered semiconductors. They consist of chalcogen-metal-chalcogen layers that are themselves bound by van der Waals forces. Hence, heterostructures involving layered compounds are abrupt and strain-free. Experimental valence-band offsets of heterostructures between GaSe, InSe, SnS2, SnSe2, MoS2, MoTe2, WSe2, and CuInSe2 and between some of these compounds and ZnSe, CdS, and CdTe as well as barrier heights of Au contacts on GaSe, InSe, MoS2, MoTe2, WSe2, ZnSe, CdS, and CdTe are analyzed. The valence-band discontinuities of the heterostructures and the barrier heights of the Schottky contact compounds are consistently described by the continuum of interface-induced gap states as the primary mechanism that governs the band lineup at semiconductor interfaces.

  7. Highly reproducible ideal SiC Schottky rectifiers: effects of surface preparation and thermal annealing on the Ni/6H-SiC barrier height

    Energy Technology Data Exchange (ETDEWEB)

    Roccaforte, F.; La Via, F.; Raineri, V. [Sezione di Catania, CNR-IMM, Stradale Primosole 50, 95121, Catania (Italy); Musumeci, P.; Calcagno, L. [INFM and Dipartimento di Fisica e Astronomia, via Santa Sofia 64, 95125, Catania (Italy); Condorelli, G.G. [Dipartimento di Chimica, viale A. Doria 6, 95125, Catania (Italy)

    2003-11-01

    In this work, the effects of surface preparation and thermal annealing on the Ni/6H-SiC Schottky barrier height were studied by monitoring the forward I-V characteristics of Schottky diodes. The ideality factor n and the barrier height {phi}{sub B} were found to be strongly dependent on the impurity species present at the metal/SiC interface. The physical mechanism which rules the Schottky barrier formation is discussed by considering the nature of the impurities left from the different surface preparation methods prior to metal deposition. In contrast, nickel silicide/SiC rectifiers (Ni{sub 2}Si/6H-SiC), formed by thermal reaction of Ni/6H-SiC above 600 C, have an almost ideal I-V curve, independent of the surface preparation. Further improvement in the barrier height distribution can be obtained by increasing the annealing temperature to 950 C. This behaviour is discussed in terms of the silicide phases and the consumption of a SiC layer during the thermal reaction. (orig.)

  8. 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.

  9. Nonlinear absorption coefficient and relative refraction index change for an asymmetrical double δ-doped quantum well in GaAs with a Schottky barrier potential

    Energy Technology Data Exchange (ETDEWEB)

    Rojas-Briseño, J.G.; Martínez-Orozco, J.C.; Rodríguez-Vargas, I. [Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad esquina con Paseo la Bufa S/N, C.P. 98060, Zacatecas, Zac. (Mexico); Mora-Ramos, M.E. [Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia); Duque, C.A., E-mail: cduque@fisica.udea.edu.co [Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia)

    2013-09-01

    In this work we are reporting the energy level spectrum for a quantum system consisting of an n-type double δ-doped quantum well with a Schottky barrier potential in a Gallium Arsenide matrix. The calculated states are taken as the basis for the evaluation of the linear and third-order nonlinear contributions to the optical absorption coefficient and to the relative refractive index change, making particular use of the asymmetry of the potential profile. These optical properties are then reported as a function of the Schottky barrier height (SBH) and the separation distance between the δ-doped quantum wells. Also, the effects of the application of hydrostatic pressure are studied. The results show that the amplitudes of the resonant peaks are of the same order of magnitude of those obtained in the case of single δ-doped field effect transistors; but tailoring the asymmetry of the confining potential profile allows the control the resonant peak positions.

  10. Evaluation of 320x240 pixel LEC GaAs Schottky barrier X-ray imaging arrays, hybridized to CMOS readout circuit based on charge integration

    CERN Document Server

    Irsigler, R; Alverbro, J; Borglind, J; Froejdh, C; Helander, P; Manolopoulos, S; O'Shea, V; Smith, K

    1999-01-01

    320x240 pixels GaAs Schottky barrier detector arrays were fabricated, hybridized to silicon readout circuits, and subsequently evaluated. The detector chip was based on semi-insulating LEC GaAs material. The square shaped pixel detector elements were of the Schottky barrier type and had a pitch of 38 mu m. The GaAs wafers were thinned down prior to the fabrication of the ohmic back contact. After dicing, the chips were indium bump, flip-chip bonded to CMOS readout circuits based on charge integration, and finally evaluated. A bias voltage between 50 and 100 V was sufficient to operate the detector. Results on I-V characteristics, noise behaviour and response to X-ray radiation are presented. Images of various objects and slit patterns were acquired by using a standard dental imaging X-ray source. The work done was a part of the XIMAGE project financed by the European Community (Brite-Euram). (author)

  11. Analysis of temperature-dependant current–voltage characteristics and extraction of series resistance in Pd/ZnO Schottky barrier diodes

    Energy Technology Data Exchange (ETDEWEB)

    Mayimele, M A, E-mail: meehleketo@gmail.com; Rensburg, J P van. Janse; Auret, F D; Diale, M

    2016-01-01

    We report on the analysis of current voltage (I–V) measurements performed on Pd/ZnO Schottky barrier diodes (SBDs) in the 80–320 K temperature range. Assuming thermionic emission (TE) theory, the forward bias I–V characteristics were analysed to extract Pd/ZnO Schottky diode parameters. Comparing Cheung’s method in the extraction of the series resistance with Ohm’s law, it was observed that at lower temperatures (T<180 K) the series resistance decreased with increasing temperature, the absolute minimum was reached near 180 K and increases linearly with temperature at high temperatures (T>200 K). The barrier height and the ideality factor decreased and increased, respectively, with decrease in temperature, attributed to the existence of barrier height inhomogeneity. Such inhomogeneity was explained based on TE with the assumption of Gaussian distribution of barrier heights with a mean barrier height of 0.99 eV and a standard deviation of 0.02 eV. A mean barrier height of 0.11 eV and Richardson constant value of 37 A cm{sup −2} K{sup −2} were determined from the modified Richardson plot that considers the Gaussian distribution of barrier heights.

  12. Direct control and characterization of a Schottky barrier by scanning tunneling microscopy

    Science.gov (United States)

    Bell, L. D.; Kaiser, W. J.; Hecht, M. H.; Grunthaner, F. J.

    1988-01-01

    Scanning tunneling microscopy (STM) methods are used to directly control the barrier height of a metal tunnel tip-semiconductor tunnel junction. Barrier behavior is measured by tunnel current-voltage spectroscopy and compared to theory. A unique surface preparation method is used to prepare a low surface state density Si surface. Control of band bending with this method enables STM investigation of semiconductor subsurface properties.

  13. The modulation of Schott ky barrier height of NiSi/n-Si Schottky diodes by silicide as diffusion source technique

    Institute of Scientific and Technical Information of China (English)

    An Xia; Fan Chun-Hui; Huang Ru; Guo Yue; Xu Cong; Zhang Xing; Wang Yang-Yuan

    2009-01-01

    This paper reports that the Schottky barrier height modulation of NiSi/n-si is experimentally investigated by adopting a novel silicide-as-diffusion-source technique. which avoids the damage to the NiSi/Si interface induced from the conventional dopant segregation method. In addition, the impact of post-BF_2 implantation after silicidation on the surface morphology of Ni silicides is also illustrated. The thermal stability of Ni silicides can be improved by sihcideas-diffusion-source technique. Besides, the electron Schottky barrier height is successfully modulated by 0.11 eV at a boron dose of 10~(15) cm~(-2) in comparison with the non. implanted samples. The change of barrier height is not attributed to the phase change of silicide films but due to the boron pile-up at the interface of NiSi and Si substrate which causes the upward bending of conducting band. The results demonstrate the feasibility of novel silicide-as-diffusion-source technique for the fabrication of Schottky source/drain Si MOS devices.

  14. Influence of neighboring coupling on metal-insulator-semiconductor (MIS) deep-depletion tunneling current via Schottky barrier height modulation mechanism

    Science.gov (United States)

    Yang, Ming-Han; Hwu, Jenn-Gwo

    2017-04-01

    A metal-insulator-semiconductor (MIS) tunneling diode is a very promising sensor due to its deep depletion phenomenon. The coupling effect between two adjacent devices is therefore of importance. To study the MIS deep-depletion tunneling current coupling phenomenon, a device pattern of one centric circle coupled with one or two surrounding rings was devised. It was found that MIS(p) tunneling current with the Schottky barrier height modulation mechanism is enhanced just by locating more MIS(p) structures nearby or by shortening their relative distance, which can again be verified under light exposure. The MIS(n) structure was also fabricated for comparison. It was observed in MIS(n) that, with the lack of the Schottky barrier height modulation mechanism, tunneling current is greater and almost immune to light irradiance compared to MIS(p). Besides, the edge oxide of MIS(p) is removed to change its Schottky barrier height modulation capability. Significantly lower deep-depletion tunneling current and invulnerability to the adjacent minority condition were observed. Surprisingly, it offers smaller saturation voltage and better photosensitivity.

  15. Schottky barrier contrasts in single and bi-layer graphene contacts for MoS2 field-effect transistors

    Science.gov (United States)

    Du, Hyewon; Kim, Taekwang; Shin, Somyeong; Kim, Dahye; Kim, Hakseong; Sung, Ji Ho; Lee, Myoung Jae; Seo, David H.; Lee, Sang Wook; Jo, Moon-Ho; Seo, Sunae

    2015-12-01

    We have investigated single- and bi-layer graphene as source-drain electrodes for n-type MoS2 transistors. Ti-MoS2-graphene heterojunction transistors using both single-layer MoS2 (1M) and 4-layer MoS2 (4M) were fabricated in order to compare graphene electrodes with commonly used Ti electrodes. MoS2-graphene Schottky barrier provided electron injection efficiency up to 130 times higher in the subthreshold regime when compared with MoS2-Ti, which resulted in VDS polarity dependence of device parameters such as threshold voltage (VTH) and subthreshold swing (SS). Comparing single-layer graphene (SG) with bi-layer graphene (BG) in 4M devices, SG electrodes exhibited enhanced device performance with higher on/off ratio and increased field-effect mobility (μFE) due to more sensitive Fermi level shift by gate voltage. Meanwhile, in the strongly accumulated regime, we observed opposing behavior depending on MoS2 thickness for both SG and BG contacts. Differential conductance (σd) of 1M increases with VDS irrespective of VDS polarity, while σd of 4M ceases monotonic growth at positive VDS values transitioning to ohmic-like contact formation. Nevertheless, the low absolute value of σd saturation of the 4M-graphene junction demonstrates that graphene electrode could be unfavorable for high current carrying transistors.

  16. Atomic and electronic structure of CdTe/metal (Cu, Al, Pt) interfaces and their influence to the Schottky barrier

    Science.gov (United States)

    Odkhuu, Dorj; Miao, Mao-sheng; Aqariden, F.; Grein, Christoph; Kioussis, Nicholas

    2016-11-01

    Schottky barrier heights (SBHs) and other features of the interfaces are determining factors for the performance of the CdTe based high-energy photon detectors. Although known for long time that SBH is sensitive to surface treatment and metal contact growth method, there is a lack of understanding of the effect of the atomic and electronic structures of CdTe/metal interface on the SBH. Employing first-principles electronic structure calculations, we have systematically studied the structural stability and electronic properties of a number of representing structures of Cd Terminated CdTe/metal (Cu, Pt, and Al) interfaces. Comparison of the total energies of the various optimized structural configurations allows to identify the existence of Te-metal alloy formation at the interface. The SBHs of Cu, Pt, and Al metal contacts with a number of stable interface structures are determined by aligning the band edges of bulk CdTe with the Fermi level of the metal/CdTe system. We find that the metal-induced states in the gap play an essential role in determining the SBH.

  17. Radiation hardness of n-type SiC Schottky barrier diodes irradiated with MeV He ion microbeam

    Science.gov (United States)

    Pastuović, Željko; Capan, Ivana; Cohen, David D.; Forneris, Jacopo; Iwamoto, Naoya; Ohshima, Takeshi; Siegele, Rainer; Hoshino, Norihiro; Tsuchida, Hidekazu

    2015-04-01

    We studied the radiation hardness of 4H-SiC Schottky barrier diodes (SBD) for the light ion detection and spectroscopy in harsh radiation environments. n-Type SBD prepared on nitrogen-doped (∼4 × 1014 cm-3) epitaxial grown 4H-SiC thin wafers have been irradiated by a raster scanning alpha particle microbeam (2 and 4 MeV He2+ ions separately) in order to create patterned damage structures at different depths within a sensitive volume of tested diodes. Deep Level Transient Spectroscopy (DLTS) analysis revealed the formation of two deep electron traps in the irradiated and not thermally treated 4H-SiC within the ion implantation range (E1 and E2). The E2 state resembles the well-known Z1/2 center, while the E1 state could not be assigned to any particular defect reported in the literature. Ion Beam Induced Charge (IBIC) microscopy with multiple He ion probe microbeams (1-6 MeV) having different penetration depths in tested partly damaged 4H-SiC SBD has been used to determine the degradation of the charge collection efficiency (CCE) over a wide fluence range of damaging alpha particle. A non-linear behavior of the CCE decrease and a significant degradation of the spectroscopic performance with increasing He ion fluence were observed above the value of 1011 cm-2.

  18. Radiation hardness of n-type SiC Schottky barrier diodes irradiated with MeV He ion microbeam

    Energy Technology Data Exchange (ETDEWEB)

    Pastuović, Željko, E-mail: zkp@ansto.gov.au [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Capan, Ivana [Material Physics Division, Institute Rudjer Boskovic, PO Box 180, 10000 Zagreb (Croatia); Cohen, David D. [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Forneris, Jacopo [Physics Department and NIS Excellence Centre, University of Torino, via P. Giuria 1, 10125 Torino (Italy); Iwamoto, Naoya; Ohshima, Takeshi [Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Siegele, Rainer [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Hoshino, Norihiro; Tsuchida, Hidekazu [Central Research Institute of Electric Power Industry, 2-6-1 Nagasaka, Yokosuka, Kanagawa 240-0196 (Japan)

    2015-04-01

    We studied the radiation hardness of 4H-SiC Schottky barrier diodes (SBD) for the light ion detection and spectroscopy in harsh radiation environments. n-Type SBD prepared on nitrogen-doped (∼4 × 10{sup 14} cm{sup −3}) epitaxial grown 4H-SiC thin wafers have been irradiated by a raster scanning alpha particle microbeam (2 and 4 MeV He{sup 2+} ions separately) in order to create patterned damage structures at different depths within a sensitive volume of tested diodes. Deep Level Transient Spectroscopy (DLTS) analysis revealed the formation of two deep electron traps in the irradiated and not thermally treated 4H-SiC within the ion implantation range (E1 and E2). The E2 state resembles the well-known Z{sub 1/2} center, while the E1 state could not be assigned to any particular defect reported in the literature. Ion Beam Induced Charge (IBIC) microscopy with multiple He ion probe microbeams (1–6 MeV) having different penetration depths in tested partly damaged 4H-SiC SBD has been used to determine the degradation of the charge collection efficiency (CCE) over a wide fluence range of damaging alpha particle. A non-linear behavior of the CCE decrease and a significant degradation of the spectroscopic performance with increasing He ion fluence were observed above the value of 10{sup 11} cm{sup −2}.

  19. Au and Al Schottky barrier formation on GaAs (100) surfaces prepared by thermal desorption of a protective arsenic coating

    Energy Technology Data Exchange (ETDEWEB)

    Spindt, C.J.; Yamada, M.; Meissner, P.L.; Miyano, K.E.; Herrera, A.; Spicer, W.E. (Stanford Electronics Laboratories, Stanford University, Stanford, California 94305-4055 (US)); Arko, A.J. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (US))

    1991-07-01

    Soft x-ray photoemission spectroscopy has been used to investigate the initial stages of Schottky barrier formation on GaAs (100) surfaces prepared by the thermal desorption of an As cap. This work was motivated by a previous study (Brillson {ital et} {ital al}., J. Vac. Sci. Technol. B {bold 6}, 1263 (1988)) of identically grown and capped samples which reported unpinned'' Schottky barrier formation, with barrier heights falling over a wide range (0.75 eV) of energies. This large energy range is a striking result, as a considerable number of prior studies on both (110) and (100) surfaces have found that all metals will pin in a narrow (0.25 eV) range near midgap. Since Au and Al are the extremes of the larger 0.75 eV span of Schottky barriers, we have studied the deposition of these two metals. We found that the barrier height measurements on the low doped {ital n}-type samples used in this work and in the paper referenced above are affected by photovoltaic effects, even at room temperature. These photovoltaic effects cause shifts in the band bending, which are an artifact of the measurement. We also performed measurements on more heavily doped samples, and the photovoltaic effects were removed. In addition, we point out that Au--Ga alloying makes the case of Au potentially misleading. With the photovoltaic effects removed, and the Au--Ga alloying carefully accounted for, we found that the barriers heights for Au and Al differ by only 0.25 eV.

  20. Temperature dependent electrical characteristics of Pt Schottky barriers fabricated on lightly and highly doped n-type 4H-SiC

    Science.gov (United States)

    Huang, Lingqin; Wang, Dejun

    2015-11-01

    The temperature dependent electronic characteristics of Pt Schottky barriers fabricated on lightly and relatively highly doped n-type 4H-SiC (1 × 1016 and 1 × 1018 cm-3) are comparatively investigated. It is found that the abnormal temperature dependence of barrier height and ideality factor estimated from the thermionic emission (TE) model for both lightly and highly doped samples could be successfully explained in terms of Gaussian distribution of inhomogeneous barrier heights. However, the estimated mean barrier height according to Gaussian distribution for the highly doped sample is much lower than the actual mean value from the capacitance-voltage (C-V) measurements. Interestingly, the values of barrier height from the thermionic field emission (TFE) model are found to be close to those from the C-V measurements, indicating that the TFE model is more appropriate to explain the electrical transport for the highly doped sample.

  1. Determination of the laterally homogeneous barrier height of palladium Schottky barrier diodes on n-Ge (111)

    CSIR Research Space (South Africa)

    Chawanda, A

    2011-05-01

    Full Text Available The authors have studied the experimental linear relationship between barrier heights and ideality factors for palladium (Pd) on bulk-grown (1 1 1) Sb-doped n-type germanium (Ge) metal-semiconductor structures with a doping density of about 2...

  2. Electronic parameters of high barrier Au/Rhodamine-101/n-Inp Schottky diode with organic Latin-Small-Letter-Dotless-I nterlayer

    Energy Technology Data Exchange (ETDEWEB)

    Guellue, Oe. [Batman University, Faculty of Sciences and Arts, Department of Physics, Batman (Turkey); Aydogan, S., E-mail: saydogan@atauni.edu.tr [Atatuerk University, Faculty of Sciences, Department of Physics, 25240-Erzurum (Turkey); Tueruet, A. [Atatuerk University, Faculty of Sciences, Department of Physics, 25240-Erzurum (Turkey)

    2012-01-01

    In this work, we present that Rhodamine-101 (Rh-101) organic molecules can control the electrical characteristics of conventional Au/n-InP metal-semiconductor contacts. An Au/n-InP Schottky junction with Rh-101 interlayer has been formed by using a simple cast process. A potential barrier height as high as 0.88 eV has been achieved for Au/Rh-101/n-InP Schottky diodes, which have good current-voltage (I-V) characteristics. This good performance is attributed to the effect of formation of interfacial organic thin layer between Au and n-InP. By using capacitance-voltage measurement of the Au/Rh-101/n-InP Schottky diode the diffusion potential and the barrier height have been calculated as 0.78 V and 0.88 eV, respectively. From the I-V measurement of the diode under illumination, short circuit current and open circuit voltage have been extracted as 1.70 {mu}A and 240 mV, respectively.

  3. The ultraviolet radiation detectors based on wide-bandgap Schottky barrier structures

    CERN Document Server

    Blank, T V; Konstantinov, O V

    2002-01-01

    Recently, much attention has been given to measure and control ultraviolet radiation (UVR) from the Sun and artificial sources. We present photodetectors based on different wide-bandgap surface-barrier structures, which exhibit linear photocurrent-radiant flux characteristics in the range 10 sup - sup 2 -10 sup 3 W/m sup 2 and can register different types of UVR. The use of light filter UFS-6 with GaP photodetector results in a spectral photosensitivity range corresponding to the Sun UV radiation if observed on Earth. The spectral sensitivity range of the photodetectors based on 4H-SiC is near the spectrum of relative effectiveness of various wavelengths in bactericidal UVR. The photosensitivity of the surface-barrier photodetectors based on wide-bandgap semiconductors exhibits the essential decline in the short-wavelength UVR region (5-6 eV), which is the region of intrinsic absorption of the semiconductor. We propose a hot exciton model, according to which the hot excitons can form in the process of the pho...

  4. Au and Al Schottky barrier formation on GaAs (100) surfaces prepared by thermal desorption of a protective arsenic coating

    Energy Technology Data Exchange (ETDEWEB)

    Spindt, C.J.; Yamada, M.; Meissner, P.L.; Miyano, K.E.; Herrera, A.; Spicer, W.E. (Stanford Univ., CA (United States). Stanford Electronics Labs.); Arko, A.J. (Los Alamos National Lab., NM (United States)); Woodall, J.M.; Pettit, G.D. (International Business Machines Corp., Yorktown Heights, NY (United States). Thomas J. Watson Research Center)

    1991-01-01

    Photoelectron spectroscopy has been used as a tool to investigate the initial stages of Schottky barrier formation on GaAs (100) surfaces. This is a popular technique that has been used by many researchers in the past to measure the band bending (or shift) of the valence band and conduction band (a measure of the Schottky barrier shift), while the Fermi level remains fixed at the system ground (i.e., the ground of the spectrometer). Metal deposition on a semiconductor surface can alter the Schottky barrier at the surface and pin the Fermi level near the middle of the energy gap. Extremely clean and crystallographically perfect surfaces are required in this study. Toward this end, a method of protecting the GaAs surface was employed which consists of capping the GaAs surface with a layer of As. Upon introduction into the high vacuum system the As is thermally desorbed, revealing a pure GaAs surface. Our work was motivated by a previous study (Brillson et al) on similarly capped specimens, which suggested that metal overlayers do not pin the Schottky barrier in GaAs. Barrier heights varied by as much as 0.75 eV between Al and Au overlayers. This large energy range is a striking result in view of the fact that a considerable number of prior studies on both (110) and (100) surfaces have found that all metals will pin within a narrow (0.25 eV) range at midgap. We repeated the measurements of Brillson on the identically doped samples used in their study using two extreme range metals of Au and Al as overlayers. We found that the barrier height measurements on low doped n-type samples used in this work and in the previous work are affected by photovoltaic effects, even at room temperature. This was determined from taking spectra at a number of temperatures between 20 K and room temperature and looking for shifts. 16 refs., 7 figs.

  5. Response of Ni/4H-SiC Schottky barrier diodes to alpha-particle irradiation at different fluences

    Energy Technology Data Exchange (ETDEWEB)

    Omotoso, E., E-mail: ezekiel.omotoso@up.ac.za [Department of Physics, University of Pretoria, Private Bag X20, Hatfield 0028 (South Africa); Departments of Physics, Obafemi Awolowo University, Ile-Ife 220005 (Nigeria); Meyer, W.E.; Auret, F.D.; Diale, M.; Ngoepe, P.N.M. [Department of Physics, University of Pretoria, Private Bag X20, Hatfield 0028 (South Africa)

    2016-01-01

    Irradiation experiments have been carried out on 1.9×10{sup 16} cm{sup −3} nitrogen-doped 4H-SiC at room temperature using 5.4 MeV alpha-particle irradiation over a fluence ranges from 2.6×10{sup 10} to 9.2×10{sup 11} cm{sup −2}. Current–voltage (I–V), capacitance–voltage (C–V) and deep level transient spectroscopy (DLTS) measurements have been carried out to study the change in characteristics of the devices and free carrier removal rate due to alpha-particle irradiation, respectively. As radiation fluence increases, the ideality factors increased from 1.20 to 1.85 but the Schottky barrier height (SBH{sub I–V}) decreased from 1.47 to 1.34 eV. Free carrier concentration, N{sub d} decreased with increasing fluence from 1.7×10{sup 16} to 1.1×10{sup 16} cm{sup −2} at approximately 0.70 μm depth. The reduction in N{sub d} shows that defects were induced during the irradiation and have effect on compensating the free carrier. The free carrier removal rate was estimated to be 6480±70 cm{sup −1}. Alpha-particle irradiation introduced two electron traps (E{sub 0.39} and E{sub 0.62}), with activation energies of 0.39±0.03 eV and 0.62±0.08 eV, respectively. The E{sub 0.39} as attribute related to silicon or carbon vacancy, while the E{sub 0.62} has the attribute of Z{sub 1}/Z{sub 2}.

  6. Prospects of zero Schottky barrier height in a graphene-inserted MoS{sub 2}-metal interface

    Energy Technology Data Exchange (ETDEWEB)

    Chanana, Anuja; Mahapatra, Santanu [Nano-Scale Device Research Laboratory, Department of Electronic Systems Engineering, Indian Institute of Science (IISc) Bangalore, Bangalore 560012 (India)

    2016-01-07

    A low Schottky barrier height (SBH) at source/drain contact is essential for achieving high drive current in atomic layer MoS{sub 2}-channel-based field effect transistors. Approaches such as choosing metals with appropriate work functions and chemical doping are employed previously to improve the carrier injection from the contact electrodes to the channel and to mitigate the SBH between the MoS{sub 2} and metal. Recent experiments demonstrate significant SBH reduction when graphene layer is inserted between metal slab (Ti and Ni) and MoS{sub 2}. However, the physical or chemical origin of this phenomenon is not yet clearly understood. In this work, density functional theory simulations are performed, employing pseudopotentials with very high basis sets to get insights of the charge transfer between metal and monolayer MoS{sub 2} through the inserted graphene layer. Our atomistic simulations on 16 different interfaces involving five different metals (Ti, Ag, Ru, Au, and Pt) reveal that (i) such a decrease in SBH is not consistent among various metals, rather an increase in SBH is observed in case of Au and Pt; (ii) unlike MoS{sub 2}-metal interface, the projected dispersion of MoS{sub 2} remains preserved in any MoS{sub 2}-graphene-metal system with shift in the bands on the energy axis. (iii) A proper choice of metal (e.g., Ru) may exhibit ohmic nature in a graphene-inserted MoS{sub 2}-metal contact. These understandings would provide a direction in developing high-performance transistors involving heteroatomic layers as contact electrodes.

  7. Response of Ni/4H-SiC Schottky barrier diodes to alpha-particle irradiation at different fluences

    Science.gov (United States)

    Omotoso, E.; Meyer, W. E.; Auret, F. D.; Diale, M.; Ngoepe, P. N. M.

    2016-01-01

    Irradiation experiments have been carried out on 1.9×1016 cm-3 nitrogen-doped 4H-SiC at room temperature using 5.4 MeV alpha-particle irradiation over a fluence ranges from 2.6×1010 to 9.2×1011 cm-2. Current-voltage (I-V), capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) measurements have been carried out to study the change in characteristics of the devices and free carrier removal rate due to alpha-particle irradiation, respectively. As radiation fluence increases, the ideality factors increased from 1.20 to 1.85 but the Schottky barrier height (SBHI-V) decreased from 1.47 to 1.34 eV. Free carrier concentration, Nd decreased with increasing fluence from 1.7×1016 to 1.1×1016 cm-2 at approximately 0.70 μm depth. The reduction in Nd shows that defects were induced during the irradiation and have effect on compensating the free carrier. The free carrier removal rate was estimated to be 6480±70 cm-1. Alpha-particle irradiation introduced two electron traps (E0.39 and E0.62), with activation energies of 0.39±0.03 eV and 0.62±0.08 eV, respectively. The E0.39 as attribute related to silicon or carbon vacancy, while the E0.62 has the attribute of Z1/Z2.

  8. PANIC (PtSi Astronomical Near-Infrared Camera) in South Africa and its astronomical applications

    Science.gov (United States)

    Tanabe, Toshihiko; Nishida, Shinji; Nakada, Yoshikazu; Matsumoto, Shigeru; Onaka, Takashi; Sekiguchi, Kazuhiro; Ono, Tomoko; Glass, Ian S.; Carter, David B.

    1996-06-01

    A large-format PtSi array (effectively 1040 by 520 pixels) has been incorporated into an astronomical infrared camera (named PANIC: PtSi astronomical near-infrared camera) intended for wide-field survey work using the 0.75-m telescope at Sutherland and the 0.4-m one at Capetown. Here we briefly describe our camera and its astronomical applications.

  9. Transport properties and electronic structure of Na0.28PtSi

    Science.gov (United States)

    Itahara, Hiroshi; Suzumura, Akitoshi; Oh, Song-Yul

    2017-07-01

    We have investigated the electronic structure and properties of Na0.28PtSi, which is a Pt-based intermetallic compound with no reported physical properties. Na0.28PtSi powder with an average grain size of 15 µm was demonstrated to be stable in a strongly acidic aqueous solution. The ab initio calculations revealed that there is a band crossing the Fermi level and that the density of states (DOS) under the Fermi level mainly consists of d orbitals of Pt atoms. Here, we used the model of Na0.25PtSi with an approximately ordered structure (space group I4, full Na site occupation), which was set instead of the reported statistically disordered structure of Na0.28PtSi (I4/mcm, Na site occupancy: 0.258). The calculated electronic structure corresponded to the measured metallic properties of the Na0.28PtSi sintered body: i.e., the electrical resistivity of Na0.28PtSi was increased from 1.77 × 10-8 Ω m at 30 K to 2.67 × 10-7 Ω m at 300 K and the Seebeck coefficient was 0.11 µV K-1 at 300 K.

  10. Estimation of power dissipation of a 4H-SiC Schottky barrier diode with a linearly graded doping profile in the drift region

    Directory of Open Access Journals (Sweden)

    Rajneesh Talwar

    2009-09-01

    Full Text Available The aim of this paper is to establish the importance of a linearly graded profile in the drift region of a 4H-SiC Schottky barrier diode (SBD. The power dissipation of the device is found to be considerably lower at any given current density as compared to its value obtained for a uniformly doped drift region. The corresponding values of breakdown voltages obtained are similar to those obtained with uniformly doped wafers of 4H-SiC.

  11. Core–shell nanospheres Pt@SiO{sub 2} for catalytic hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Yujuan; Wang, Yuqing; Lu, Zhang-Hui, E-mail: luzh@jxnu.edu.cn; Chen, Xiangshu, E-mail: cxs66cn@jxnu.edu.cn; Xiong, Lihua

    2015-06-30

    Highlights: • Pt@SiO{sub 2} core–shell NPs are synthesized via a simple one-pot synthetic route. • Ultrafine Pt NPs (∼4 nm) are embedded in well-proportioned SiO{sub 2} nanospheres. • Pt@SiO{sub 2} shows a high activity and good durability for H{sub 2} generation from AB. - Abstract: Ultrafine platinum nanoparticles (NPs) embedded in silica nanospheres (Pt@SiO{sub 2}) have been synthesized in a NP-5/cyclohexane reversed-micelle system followed by NaBH{sub 4} reduction. The as-synthesized core–shell nanocatalysts Pt@SiO{sub 2} were characterized by scanning electron microscopy, transmission electron microscopes, X-ray powder diffraction analysis, energy dispersive X-ray spectrometer and nitrogen adsorption–desorption investigations. Interestingly, the as-synthesized core–shell nanocatalysts Pt@SiO{sub 2} showed an excellent catalytic performance in hydrogen generation from the hydrolysis of ammonia borane (BH{sub 3}NH{sub 3}, AB) at room temperature. Especially, the catalytic performance of the Pt@SiO{sub 2} remained almost unchanged after the five recycles and even after the heat treatment (673 K), because the silica shells inhibit aggregation or deformation of the metal cores. Besides, the kinetic studies showed that the catalytic hydrolysis of AB was first order with respect to the catalyst concentration and zero order with respect to the substrate concentration, respectively. The excellent catalytic activity and stability of Pt@SiO{sub 2} can make it have a bright future in the practical application.

  12. Crystal structure and superconductivity in the Th-doped LaPtSi compounds

    Energy Technology Data Exchange (ETDEWEB)

    Chen, J.Y.; Sung, H.H.; Syu, K.J. [Department of Physics, National Chung Cheng University, Ming-Hsiung, Chia-Yi, Taiwan (China); Lee, W.H., E-mail: whlee@phy.ccu.edu.t [Department of Physics, National Chung Cheng University, Ming-Hsiung, Chia-Yi, Taiwan (China)

    2010-12-15

    As observed with X-ray powder diffraction, the tetragonal structure of the parent compound LaPtSi, which crystallizes in the LaPtSi-type structure with space group I4{sub 1}md, is retained in (La{sub 1-x}Th{sub x})PtSi up to the solubility limit near x = 0.5. By considering the size factor of Hume-Rothery theory of alloy phase formation, it is not marvelous that the extensive solid solutions cannot be fully completed in (La{sub 1-x}Th{sub x})PtSi. We present the room temperature powder X-ray diffraction patterns, the room temperature lattice parameters and the dc magnetic susceptibility between 1.8 and 4.0 K for three single phase polycrystalline samples in (La{sub 1-x}Th{sub x})PtSi with x 0, 0.25 and 0.50. The refined lattice parameters show that both the a-axis and the volume of the unit cell v contract clearly, though the c-axis gives a less percentage expansion due to doping with thorium. It is found that the change in T{sub c} with x is similar to the change in the lattice parameter a or v, which indicates that the stiffening of the lattice under pressure has a dominant effect on the decrease in T{sub c} in this system.

  13. Ferroelectricity-modulated resistive switching in Pt/Si:HfO2/HfO2-x /Pt memory

    Science.gov (United States)

    Ran, Jiang; Xianghao, Du; Zuyin, Han

    2016-08-01

    It is investigated for the effect of a ferroelectric Si:HfO2 thin film on the resistive switching in a stacked Pt/Si:HfO2/highly-oxygen-deficient HfO2-x /Pt structure. Improved resistance performance was observed. It was concluded that the observed resistive switching behavior was related to the modulation of the width and height of a depletion barrier in the HfO2-x layer, which was caused by the Si:HfO2 ferroelectric polarization field effect. Reliable switching reproducibility and long data retention were observed in these memory cells, suggesting their great potential in non-volatile memories applications with full compatibility and simplicity. Project supported by the National Natural Science Foundation of China (No. 11374182), the Natural Science Foundation of Shandong Province (No. ZR2012FQ012), and the Jinan Independent Innovation Projects of Universities (No. 201303019).

  14. Highly efficient ZnO/Au Schottky barrier dye-sensitized solar cells: Role of gold nanoparticles on the charge-transfer process

    Directory of Open Access Journals (Sweden)

    Tanujjal Bora

    2011-10-01

    Full Text Available Zinc oxide (ZnO nanorods decorated with gold (Au nanoparticles have been synthesized and used to fabricate dye-sensitized solar cells (DSSC. The picosecond-resolved, time-correlated single-photon-count (TCSPC spectroscopy technique was used to explore the charge-transfer mechanism in the ZnO/Au-nanocomposite DSSC. Due to the formation of the Schottky barrier at the ZnO/Au interface and the higher optical absorptions of the ZnO/Au photoelectrodes arising from the surface plasmon absorption of the Au nanoparticles, enhanced power-conversion efficiency (PCE of 6.49% for small-area (0.1 cm2 ZnO/Au-nanocomposite DSSC was achieved compared to the 5.34% efficiency of the bare ZnO nanorod DSSC. The TCSPC studies revealed similar dynamics for the charge transfer from dye molecules to ZnO both in the presence and absence of Au nanoparticles. A slower fluorescence decay associated with the electron recombination process, observed in the presence of Au nanoparticles, confirmed the blocking of the electron transfer from ZnO back to the dye or electrolyte by the Schottky barrier formed at the ZnO/Au interface. For large area DSSC (1 cm2, ~130% enhancement in PCE (from 0.50% to 1.16% was achieved after incorporation of the Au nanoparticles into the ZnO nanorods.

  15. Investigation of Schottky Barriers

    Science.gov (United States)

    1989-12-01

    gallium site was favored; this is consistent with the earlier tight-binding treatment[13]. In addition, the total energy difference per primitive cell (each... primitive cell contained one aluminum adatom) was 0.36 eV. The tight-binding energy differ- ence was 0.30 eV[15]. The agreement between the two...the gallium and arsenic sites) and two interstitial sites in every primitive cell . We have performed the calculations for several different coverages

  16. High-voltage 4H-SiC trench MOS barrier Schottky rectifier with low forward voltage drop using enhanced sidewall layer

    Science.gov (United States)

    Cho, Doohyung; Sim, Seulgi; Park, Kunsik; Won, Jongil; Kim, Sanggi; Kim, Kwangsoo

    2015-12-01

    In this paper, a 4H-SiC trench MOS barrier Schottky (TMBS) rectifier with an enhanced sidewall layer (ESL) is proposed. The proposed structure has a high doping concentration at the trench sidewall. This high doping concentration improves both the reverse blocking and forward characteristics of the structure. The ESL-TMBS rectifier has a 7.4% lower forward voltage drop and a 24% higher breakdown voltage. However, this structure has a reverse leakage current that is approximately three times higher than that of a conventional TMBS rectifier owing to the reduction in energy barrier height. This problem is solved when ESL is used partially, since its use provides a reverse leakage current that is comparable to that of a conventional TMBS rectifier. Thus, the forward voltage drop and breakdown voltage improve without any loss in static and dynamic characteristics in the ESL-TMBS rectifier compared with the performance of a conventional TMBS rectifier.

  17. Pt-Si Bifunctional Surfaces for CO and Methanol Electro-Oxidation

    DEFF Research Database (Denmark)

    Permyakova, Anastasia A.; Han, Binghong; Jensen, Jens Oluf

    2015-01-01

    Bimetallic surfaces offer activity benefits derived from synergistic effects among active sites with uniquely different functions, which is particularly important for the development of highly effective heterogeneous catalysts for specific technological applications, such as energy conversion...... and storage. Here we report on Pt-Si bulk samples prepared by arc-melting, for the first time, with high activities toward the electro-oxidation of CO and methanol. Increasing the Si concentration on the surface was correlated with the shifts of onset oxidation potentials to lower values and higher activities...... for CO and methanol electro-oxidation. It is proposed that the reaction on the Pt-Si catalyst could follow a Langmuir-Hinshelwood type of mechanism, where substantially enhanced catalytic activity is attributed to the fine-tuning of the surface Pt-Si atomic structure....

  18. Bifunctional Pt-Si Alloys for Small Organic Molecule Electro-oxidation

    DEFF Research Database (Denmark)

    Permyakova, Anastasia Aleksandrovna; Suntivich, Jin; Han, Binghong

    Designing highly active catalysts for electro-oxidation of small organic molecules can help to reduce the anodic overpotential for more efficient utilization of hydrocarbon fuels. The challenge in developing more active electrocatalysts for electro-oxidation reactions is to satisfy the stringent...... bifunctional requirement, which demands both adsorption and water oxidation sites. In this contribution, we explore the possibility of using Pt-Si alloys to fulfill this bifunctional requirement. Silicon, a highly oxophillic element, is alloyed into Pt as a site for water oxidation, while Pt serves as a CO...... adsorption site. We will discuss the enhanced activity of Pt-Si alloys for small organic molecule oxidation, which can be attributed to the improved CO electro-oxidation kinetics on Pt-Si....

  19. Observation of strain relaxation in Si{sub 1-x}Ge{sub x} layers by optical and electrical characterisation of a Schottky junction

    Energy Technology Data Exchange (ETDEWEB)

    Turan, R.; Aslan, B. [Middle East Technical Univ., Ankara (Turkey). Dept. of Physics; Nur, O.; Yousif, M.Y.A.; Willander, M. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Physics

    2001-05-01

    We have studied the effect of the strain relaxation on the band-edge alignments in a Pt/p-Si{sub 1-x}Ge{sub x} Schottky junction with x=0.14 by internal photoemission spectroscopy and current-voltage measurements. We have shown that the variations in the band-edge alignments can be observed directly by measuring the optical and electrical properties of a simple Schottky junction. The strain in the Si{sub 1-x}Ge{sub x} layer has been partially relaxed by thermal treatments at two different temperatures. The degree of relaxation and other structural changes have been determined by a high-resolution X-ray diffractometer. Both optical and electrical techniques have shown that the barrier height of the Pt/Si{sub 0.86}Ge{sub 0.14} junction increases with the amount of relaxation in the Si{sub 1-x}Ge{sub x} layer. This shows that the valence-band edge of the Si{sub 1-x}Ge{sub x} layer moves away from the Fermi level of the Pt/Si{sub 1-x}Ge{sub x} junction. The band-edge movement results from the increase in the band gap of the Si{sub 1-x}Ge{sub x} layer after the strain relaxation. This result agrees with the theoretical predictions for the strain-induced effects on the Si{sub 1-x}Ge{sub x} band structure. (orig.)

  20. Highly sensitive hydrogen sensor based on graphite-InP or graphite-GaN Schottky barrier with electrophoretically deposited Pd nanoparticles

    Directory of Open Access Journals (Sweden)

    Zdansky Karel

    2011-01-01

    Full Text Available Abstract Depositions on surfaces of semiconductor wafers of InP and GaN were performed from isooctane colloid solutions of palladium (Pd nanoparticles (NPs in AOT reverse micelles. Pd NPs in evaporated colloid and in layers deposited electrophoretically were monitored by SEM. Diodes were prepared by making Schottky contacts with colloidal graphite on semiconductor surfaces previously deposited with Pd NPs and ohmic contacts on blank surfaces. Forward and reverse current-voltage characteristics of the diodes showed high rectification ratio and high Schottky barrier heights, giving evidence of very small Fermi level pinning. A large increase of current was observed after exposing diodes to flow of gas blend hydrogen in nitrogen. Current change ratio about 700,000 with 0.1% hydrogen blend was achieved, which is more than two orders-of-magnitude improvement over the best result reported previously. Hydrogen detection limit of the diodes was estimated at 1 ppm H2/N2. The diodes, besides this extremely high sensitivity, have been temporally stable and of inexpensive production. Relatively more expensive GaN diodes have potential for functionality at high temperatures.

  1. Highly sensitive hydrogen sensor based on graphite-InP or graphite-GaN Schottky barrier with electrophoretically deposited Pd nanoparticles

    Science.gov (United States)

    Zdansky, Karel

    2011-08-01

    Depositions on surfaces of semiconductor wafers of InP and GaN were performed from isooctane colloid solutions of palladium (Pd) nanoparticles (NPs) in AOT reverse micelles. Pd NPs in evaporated colloid and in layers deposited electrophoretically were monitored by SEM. Diodes were prepared by making Schottky contacts with colloidal graphite on semiconductor surfaces previously deposited with Pd NPs and ohmic contacts on blank surfaces. Forward and reverse current-voltage characteristics of the diodes showed high rectification ratio and high Schottky barrier heights, giving evidence of very small Fermi level pinning. A large increase of current was observed after exposing diodes to flow of gas blend hydrogen in nitrogen. Current change ratio about 700,000 with 0.1% hydrogen blend was achieved, which is more than two orders-of-magnitude improvement over the best result reported previously. Hydrogen detection limit of the diodes was estimated at 1 ppm H2/N2. The diodes, besides this extremely high sensitivity, have been temporally stable and of inexpensive production. Relatively more expensive GaN diodes have potential for functionality at high temperatures.

  2. Correlation between barrier inhomogeneities of 4H-SiC 1 A/600 V Schottky rectifiers and deep-level defects revealed by DLTS and Laplace DLTS

    Science.gov (United States)

    Gelczuk, Ł.; Kamyczek, P.; Płaczek-Popko, E.; Dąbrowska-Szata, M.

    2014-09-01

    Electrical properties of commercial silicon carbide (SiC) Schottky rectifiers are investigated through the measurement and analysis of the forward current-voltage (I-V) and reverse capacitance-voltage (C-V) characteristics in a large temperature range. Some of devices show distinct discrepancies in specific ranges of their electrical characteristics, especially the excess current dominates at voltage <1 V and temperature <300 K. Standard deep level transient spectroscopy (DLTS) revealed the presence of a single deep-level defect with activation energy of about 0.3 eV, exhibiting the features characteristic for extended defects (e.g. dislocations), such as logarithmic capture kinetics. Furthermore, high-resolution Laplace DLTS showed that this deep level consists actually of three closely spaced levels with activation energies ranging from about 0.26 eV to 0.29 eV. A strong correlation between these two techniques implies that the revealed trap level is due to extended defects surrounded by point traps or clusters of defects. On the basis of obtained specific features of the deep-level defect, it was proposed that this defect is arguably responsible for the observed Schottky barrier inhomogeneities.

  3. Porous anodic alumina on galvanically grown PtSi layer for application in template-assisted Si nanowire growth

    Directory of Open Access Journals (Sweden)

    Stavrinidou Eleni

    2011-01-01

    Full Text Available Abstract We report on the fabrication and morphology/structural characterization of a porous anodic alumina (PAA/PtSi nano-template for use as matrix in template-assisted Si nanowire growth on a Si substrate. The PtSi layer was formed by electroless deposition from an aqueous solution containing the metal salt and HF, while the PAA membrane by anodizing an Al film deposited on the PtSi layer. The morphology and structure of the PtSi layer and of the alumina membrane on top were studied by Scanning and High Resolution Transmission Electron Microscopies (SEM, HRTEM. Cross sectional HRTEM images combined with electron diffraction (ED were used to characterize the different interfaces between Si, PtSi and porous anodic alumina.

  4. Analysis of the effect of sidewall on the performance of 6H-SiC Schottky barrier source/drain NMOSFETs

    Institute of Scientific and Technical Information of China (English)

    Tang Xiao-Yan; Zhang Yi-Men; Zhang Yu-Ming; Gao Jin-Xia

    2004-01-01

    Between source/drain and gate of SiC Schottky barrier source/drain MOSFET (SiC SBSD-MOSFET), there must be a sidewall as isolation. The width of sidewall strongly affects on the device performance. In this paper the effect of sidewall on the performance of 6H-SiC SBSD-NMOSFET is simulated with the 2D simulator MEDICI. The simulated results show that a sidewall with width less than 0.1μm slightly affects the device performance. However, when the width of sidewall exceeds 0.1μm, the conduction does not occur until the drain voltage is high enough and saturation current sharply decreases. The effect of the sidewall on device performance can be reduced by decreasing the doping concentration in the epitaxial layer.

  5. Physical Modeling of Gate-Controlled Schottky Barrier Lowering of Metal-Graphene Contacts in Top-Gated Graphene Field-Effect Transistors.

    Science.gov (United States)

    Mao, Ling-Feng; Ning, Huansheng; Huo, Zong-Liang; Wang, Jin-Yan

    2015-12-17

    A new physical model of the gate controlled Schottky barrier height (SBH) lowering in top-gated graphene field-effect transistors (GFETs) under saturation bias condition is proposed based on the energy conservation equation with the balance assumption. The theoretical prediction of the SBH lowering agrees well with the experimental data reported in literatures. The reduction of the SBH increases with the increasing of gate voltage and relative dielectric constant of the gate oxide, while it decreases with the increasing of oxide thickness, channel length and acceptor density. The magnitude of the reduction is slightly enhanced under high drain voltage. Moreover, it is found that the gate oxide materials with large relative dielectric constant (>20) have a significant effect on the gate controlled SBH lowering, implying that the energy relaxation of channel electrons should be taken into account for modeling SBH in GFETs.

  6. Experimental and numerical analyses of high voltage 4H-SiC junction barrier Schottky rectifiers with linearly graded field limiting ring

    Science.gov (United States)

    Wang, Xiang-Dong; Deng, Xiao-Chuan; Wang, Yong-Wei; Wang, Yong; Wen, Yi; Zhang, Bo

    2014-05-01

    This paper describes the successful fabrication of 4H-SiC junction barrier Schottky (JBS) rectifiers with a linearly graded field limiting ring (LG-FLR). Linearly variable ring spacings for the FLR termination are applied to improve the blocking voltage by reducing the peak surface electric field at the edge termination region, which acts like a variable lateral doping profile resulting in a gradual field distribution. The experimental results demonstrate a breakdown voltage of 5 kV at the reverse leakage current density of 2 mA/cm2 (about 80% of the theoretical value). Detailed numerical simulations show that the proposed termination structure provides a uniform electric field profile compared to the conventional FLR termination, which is responsible for 45% improvement in the reverse blocking voltage despite a 3.7% longer total termination length.

  7. Surge current capabilities and isothermal current-voltage characteristics of high-voltage 4H-SiC junction barrier Schottky rectifiers

    Science.gov (United States)

    Palmour, J. W.; Levinshtein, M. E.; Ivanov, P. A.; Zhang, Q. J.

    2015-06-01

    Isothermal forward current-voltage characteristics of high-voltage 4H-SiC junction barrier Schottky rectifiers (JBS) have been studied for the first time. Isothermal characteristics were measured with JBS having a blocking voltage of 1700 V up to a current density j  ≈  4200 A cm-2 in the temperature range 297-460 K. Quasi-isothermal current-voltage characteristics of these devices were studied with injection of minority carriers (holes) up to j  ≈  7200 A cm-2 and ambient temperatures of 297 and 460 K. The isothermal forward current-voltage characteristics make it possible to numerically calculate (for example, by an iteration procedure) the overheating in an arbitrary operation mode.

  8. Influence of three-dimensional p-buried layer pattern on the performance of 4H-SiC floating junction Schottky barrier diode

    Science.gov (United States)

    Yang, Shuai; Zhang, Yuming; Song, Qingwen; Tang, Xiaoyan; Zhang, Yimen; Huo, Tianjia; Liu, Sicheng; Yuan, Hao

    2015-10-01

    4H-SiC floating junction Schottky barrier diodes (FJ-SBDs) are excellent SiC devices with high Baliga’s figure of merit (BFOM). However, the p-type buried layers in epilayers partially obstruct the current paths, and increase the on-resistance, while the buried layers of dot patterns can reduce the obstruction. In this paper, a three-dimensional (3D) simulation of 4H-SiC FJ-SBDs with dot patterns is reported for the first time. By comparing the results obtained from stripe, square, octagon, and circle patterns, dot patterns are proved to be good choices for buried layers in 4H-SiC FJ-SBDs, and the FJ-SBD with the circle pattern has the highest BFOM of 12.09 GW/cm2, which is 22.62% greater than that of the FJ-SBD with the stripe pattern.

  9. Capacitance-voltage profile characteristics of Schottky barrier structure with InAs quantum dots grown on InAlAs/InP(001)

    Energy Technology Data Exchange (ETDEWEB)

    Baira, M. [Laboratoire de Physique des Semiconducteurs et des Composants Electroniques, Departement de Physique, Faculte des Sciences, 5019 Monastir (Tunisia); Ajjel, R. [Laboratoire de Physique des Semiconducteurs et des Composants Electroniques, Departement de Physique, Faculte des Sciences, 5019 Monastir (Tunisia)]. E-mail: ridha.ajjel@fsm.rnu.tn; Maaref, H. [Laboratoire de Physique des Semiconducteurs et des Composants Electroniques, Departement de Physique, Faculte des Sciences, 5019 Monastir (Tunisia); Salem, B. [Laboratoire de Physique de la Matiere-LPM (UMR-CNRS 5511), INSA de Lyon, Batiment Blaise Pascal, 7 Avenue J. Capelle, 69621 Villeurbanne (France); Bremond, G. [Laboratoire de Physique de la Matiere-LPM (UMR-CNRS 5511), INSA de Lyon, Batiment Blaise Pascal, 7 Avenue J. Capelle, 69621 Villeurbanne (France); Gendry, M. [Laboratoire d' Electronique, Optoelectronique et Microsystemes-LEOM (UMR-CNRS 5512), Ecole Centrale de Lyon, 36 Avenue G. de Collongue, 69134 Ecully (France); Marty, O. [Laboratoire d' Electronique-LENAC, Universite Lyon 1, F-69622 Villeurbanne, Lyon (France)

    2006-03-15

    Capacitance-voltage, C(V) studies have been carried out on Schottky barrier structure containing a sheet of self-organized InAs quantum dots (QDs) grown on InAlAs lattice matched to InP in order to deduce the electrical properties of the QDs. Three electron levels have been detected in n-type material, and were attributed to the s ground, the p excited, and the d excited states. Some parameters of the structure, such as the position of the InAs QD plane, the electron concentration in the QDs and an approximate QD height were deduced from the C(V) profile analysis. These results are in good agreement with the transmission electron microscopy (TEM) study realized on the structure.

  10. Effect of gating and pressure on the electronic transport properties of crossed nanotube junctions: formation of a Schottky barrier

    Energy Technology Data Exchange (ETDEWEB)

    Havu, P; Hashemi, M J; Kaukonen, M; Nieminen, R M [Department of Applied Physics, Aalto University, PO Box 11100, FI-00076 Aalto (Finland); Seppaelae, E T [Nokia Research Center, Itaemerenkatu 11-13, FI-00180 Helsinki (Finland)

    2011-03-23

    The electronic transport properties of crossed carbon nanotube junctions are investigated using ab initio methods. The optimal atomic structures and the intertube distances of the junctions are obtained using van der Waals corrected density functional theory. The effect of gating on the intertube conductance of the junctions is explored, showing the charge accumulation to the nanotube contact and the charge depletion region at the metal-semiconductor Schottky contact. Finally, it is shown how the conductance of the junctions under the gate voltage is affected by pressure applied to the nanotube film. (fast track communication)

  11. Modification of metal–InGaAs Schottky barrier behaviour by atomic layer deposition of ultra-thin Al{sub 2}O{sub 3} interlayers

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Lalit [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland); Gupta, Suman; Jaiswal, Piyush; Bhat, Navakanta; Shivashankar, S.A. [Centre for Nano Science and Engineering (CeNSE), Indian Institute of Science, Bangalore 560012 (India); Hughes, G. [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland)

    2015-08-31

    The effect of inserting ultra-thin atomic layer deposited Al{sub 2}O{sub 3} dielectric layers (1 nm and 2 nm thick) on the Schottky barrier behaviour for high (Pt) and low (Al) work function metals on n- and p-doped InGaAs substrates has been investigated. Rectifying behaviour was observed for the p-type substrates (both native oxide and sulphur passivated) for both the Al/p-InGaAs and Al/Al{sub 2}O{sub 3}/p-InGaAs contacts. The Pt contacts directly deposited on p-InGaAs displayed evidence of limited rectification which increased with Al{sub 2}O{sub 3} interlayer thickness. Ohmic contacts were formed for both metals on n-InGaAs in the absence of an Al{sub 2}O{sub 3} interlayer, regardless of surface passivation. However, limited rectifying behaviour was observed for both metals on the 2 nm Al{sub 2}O{sub 3}/n-InGaAs samples for the sulphur passivated InGaAs surface, indicating the importance of both surface passivation and the presence of an ultra-thin dielectric interlayer on the current–voltage characteristics displayed by these devices. - Highlights: • Investigation of the modification of metal–InGaAs Schottky barrier (SB) behaviour • Improving metal–InGaAs interface by sulphur passivation and ultrathin interlayer • Examine the effect of low work function and high work function metals on SB • Different SB behaviours observed on both n-type InGaAs and p-type InGaAs • Metal/n-InGaAs interface is more strongly pinned than the metal/p-InGaAs interface.

  12. Electronic structure and Schottky-barrier formation on GaAs (100) surfaces prepared by thermal desorption of a protective arsenic coating

    Energy Technology Data Exchange (ETDEWEB)

    Spindt, C.J.; Yamada, M.; Meissner, P.L.; Miyano, K.E.; Kendelewicz, T.; Herrera-Gomez, A.; Spicer, W.E. (Stanford Electronics Laboratories, Stanford University, Stanford, California 94305-4055 (United States)); Arko, A.J. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States))

    1992-05-15

    Soft-x-ray photoemission spectroscopy has been used to characterize GaAs(100) surfaces and interfaces grown by molecular-beam epitaxy and prepared by the thermal desorption of a protective As coating. The samples studied were grown and arsenic capped identically to those used in a previous study (Brillson {ital et} {ital al}., J. Vac. Sci. Technol. B 6, 1263 (1988)). In this previous work, unpinned'' Schottky-barrier formation was reported, with barrier heights over a wide (0.75-eV) range. This is a striking result, as it was previously believed that all metals will pin GaAs surfaces in a narrow energy range near the middle of the band gap. This large range of barrier heights later led to the suggestion that the (100) surface could become an insulating layer that could screen out the effects of metal-induced gap states. Motivated by this work, we have studied Al and Au Schottky barriers since the deposition of these two metals gave the extreme low and high barriers in the 0.75-eV range. We have also characterized the clean surfaces prepared by desorbing the As caps at different temperatures. The As 3{ital d} and Ga 3{ital d} core levels showed that the surface stoichiometry could be varied significantly with the desorption temperature. The As 3{ital d} line shape was found to be the best indication of the surface stoichiometry after the anneal. The valence-band spectra did not show any strong features which could be used to determine when the sample was completely decapped. The electronic structure of the surface layer was investigated experimentally, and no evidence of an insulating reconstruction was found. In our study of band bending, we found that the low-doped samples used here and in the earlier study showed significant photovoltages resulting in incorrect band-bending measurements. We also found that the Au measurements are made difficult by the presence of core-level shifts due to Au-Ga alloying.

  13. The electronic and chemical structure of the a-B3CO0.5:Hy-to-metal interface from photoemission spectroscopy: implications for Schottky barrier heights.

    Science.gov (United States)

    Driver, M Sky; Paquette, Michelle M; Karki, S; Nordell, B J; Caruso, A N

    2012-11-01

    The electronic and chemical structure of the metal-to-semiconductor interface was studied by photoemission spectroscopy for evaporated Cr, Ti, Al and Cu overlayers on sputter-cleaned as-deposited and thermally treated thin films of amorphous hydrogenated boron carbide (a-B(x)C:H(y)) grown by plasma-enhanced chemical vapor deposition. The films were found to contain ~10% oxygen in the bulk and to have approximate bulk stoichiometries of a-B(3)CO(0.5):H(y). Measured work functions of 4.7/4.5 eV and valence band maxima to Fermi level energy gaps of 0.80/0.66 eV for the films (as-deposited/thermally treated) led to predicted Schottky barrier heights of 1.0/0.7 eV for Cr, 1.2/0.9 eV for Ti, 1.2/0.9 eV for Al, and 0.9/0.6 eV for Cu. The Cr interface was found to contain a thick partial metal oxide layer, dominated by the wide-bandgap semiconductor Cr(2)O(3), expected to lead to an increased Schottky barrier at the junction and the formation of a space-charge region in the a-B(3)CO(0.5):H (y) layer. Analysis of the Ti interface revealed a thick layer of metal oxide, comprising metallic TiO and Ti (2)O (3), expected to decrease the barrier height. A thinner, insulating Al(2)O(3) layer was observed at the Al-to-a-B(3)CO(0.5):H(y) interface, expected to lead to tunnel junction behavior. Finally, no metal oxides or other new chemical species were evident at the Cu-to-a-B(3)CO(0.5):H(y) interface in either the core level or valence band photoemission spectra, wherein characteristic metallic Cu features were observed at very thin overlayer coverages. These results highlight the importance of thin-film bulk oxygen content on the metal-to-semiconductor junction character as well as the use of Cu as a potential Ohmic contact material for amorphous hydrogenated boron carbide semiconductor devices such as high-efficiency direct-conversion solid-state neutron detectors.

  14. Spin accumulation at in-situ grown Fe/GaAs(100) Schottky barriers measured using the three- and four-terminal methods

    Science.gov (United States)

    Nam, Song Hyeon; Park, Tae-Eon; Park, Youn Ho; Ihm, Hae-In; Koo, Hyun Cheol; Kim, Hyung-jun; Han, Suk Hee; Chang, Joonyeon

    2016-09-01

    We examined the spin accumulation in Fe/n-GaAs Schottky barriers to evaluate the accuracy of the three-terminal (3T) and four-terminal (4T) measurement geometries. A fully epitaxial Fe/n-GaAs junction was grown in situ using cluster molecular beam epitaxy without breaking the vacuum to exclude the formation of an oxide layer or surface roughness at the interface during intermixing. The spin resistance of the 4T nonlocal spin valve (ΔRNLSV = 0.71 Ω) was twice the value obtained using the 4T Hanle effect method (ΔR4TH = 0.35 Ω) at 10 K, as predicted theoretically, and this value remained constant over the temperature range examined, from 10 K to 77 K. The temperature-dependent spin lifetimes measured using the 3T and 4T Hanle effects exhibited similar behaviors. Although the spin resistance obtained using the 3T Hanle effect was enhanced compared with that obtained using the 4T effect, it was reasonable to conclude that the spin signals obtained from the 3T and 4T measurements originated from spin accumulation in n-GaAs due to the absence of an oxide tunnel barrier or a well-defined interface in our samples. These results completely ruled out any other sources of artifacts.

  15. Application of Pt/SiO2-CNTs Nano Catalysts in EthanolElectro-oxidation%乙醇在Pt/SiO2-CNTs纳米催化剂上的电催化氧化

    Institute of Scientific and Technical Information of China (English)

    朱静; 李路; 韦小刚

    2011-01-01

    通过溶胶凝胶方法制备SiO2修饰的碳纳米管(SiO2-CNTs)为载体材料,利用微波辅助加热化学还原方法制备Pt/SiO2-CNTs电催化剂。然后分别利用扫描电子显微镜和能量散射谱仪对Pt/SiO2-CNTs电催化剂的表面形貌和元素组成进行了表征。在酸性介质中,采用循环伏安法研究了Pt/SiO2-C电催化剂对乙醇氧化的电催化活性。与商用催化剂PtRu/C电催化剂相比,在相同催化剂载量和实验条件下,Pt/SiO2-CNTs电催化剂具有更好的催化活性和抗CO中毒能力。%The SiO2 modified carbon nanotubes were prepared through sol-gel method and used as catalyst support.The Pt/SiO2-CNTs were synthesized by microwave-assisted chemical reduction method.The micrograph and the elemental composition of Pt/SiO2-CNTs nanoparticles were characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy,respectively.The electrocatalytic properties of Pt/SiO2-CNTs electrocatalyst for ethanol oxidation were investigated by cyclic voltammetry in acidic solution.Under the same catalyst loading mass and experimental conditions,the Pt/SiO2-C electrocatalyst shows higher catalytic activities than PtRu/C catalyst.It also possesses good anti-poisoning ability.

  16. Non-UV Photoelectric Properties of the Ni/n-Si/N+-SiC Isotype Heterostructure Schottky Barrier Photodiode

    Science.gov (United States)

    Li, Lian-Bi; Chen, Zhi-Ming; Ren, Zhan-Qiang; Gao, Zhan-Jun

    2013-09-01

    The energy-band structure and non-ultraviolet photoelectric properties of a Ni/n-Si/N+-SiC isotype heterostructure Schottky photodiode are simulated by using Silvaco-Atlas. There are energy offsets in the conduction and valance band of the heterojunction, which are about 0.09 eV and 1.79 eV, respectively. The non-UV photodiode with this structure is fabricated on a 6H-SiC(0001) substrate. J—V measurements indicate that the device has good rectifying behavior with a rectification ratio up to 200 at 5 V, and the turn-on voltage is about 0.7 V. Under non-ultraviolet illumination of 0.6 W/cm2, the device demonstrates a significant photoelectric response with a photocurrent density of 2.9 mA/cm2 and an open-circuit voltage of 63.0 mV. Non-ultraviolet operation of the SiC-based photoelectric device is initially realized.

  17. Properties of Schottky Barrier Diodes on (In(x)Ga(1-x))₂O₃ for 0.01 ≤ x ≤ 0.85 Determined by a Combinatorial Approach.

    Science.gov (United States)

    von Wenckstern, H; Splith, D; Werner, A; Müller, S; Lorenz, M; Grundmann, M

    2015-12-14

    We investigated properties of an (In(x)Ga(1-x))2O3 thin film with laterally varying cation composition that was realized by a large-area offset pulsed laser deposition approach. Within a two inch diameter thin film, the composition varies between 0.01 ≤ x ≤ 0.85, and three crystallographic phases (cubic, hexagonal, and monoclinic) were identified. We observed a correlation between characteristic parameters of Schottky barrier diodes fabricated on the thin film and its chemical and structural material properties. The highest Schottky barriers and rectification of the diodes were found for low indium contents. The thermal stability of the diodes is also best for Ga-rich parts of the sample. Conversely, the series resistance is lowest for large In content. Overall, the (In(x)Ga(1-x))2O3 alloy is well-suited for potential applications such as solar-blind photodetectors with a tunable absorption edge.

  18. Gate Modulation of Graphene-ZnO Nanowire Schottky Diode

    OpenAIRE

    Liu, Ren; You, Xu-Chen; Fu, Xue-Wen; Lin, Fang; Meng, Jie; Yu, Da-Peng; Liao, Zhi-Min

    2015-01-01

    Graphene-semiconductor interface is important for the applications in electronic and optoelectronic devices. Here we report the modulation of the electric transport properties of graphene/ZnO nanowire Schottky diode by gate voltage (Vg). The ideality factor of the graphene/ZnO nanowire Schottky diode is ~1.7, and the Schottky barrier height is ~0.28 eV without external Vg. The Schottky barrier height is sensitive to Vg due to the variation of Fermi level of graphene. The barrier height increa...

  19. Enhanced photo-response properties of a single ZnO microwire photodetector by coupling effect between localized Schottky barriers and piezoelectric potential.

    Science.gov (United States)

    Li, Haixia; Zhang, Xianghui; Liu, Nishuang; Ding, Longwei; Tao, Jiayou; Wang, Siliang; Su, Jun; Li, Luying; Gao, Yihua

    2015-08-10

    The coupling effect between localized Schottky barriers (SBs) and piezoelectric potential that impact the photo-response properties of a single ZnO microwire (MW) photodetector (PD) is studied. Localized SBs is introduced by Au NPs decoration. The negatively charged Au NPs deplete more carriers near the ZnO surface, which raises the SB height and sharply reduces the recover time of the PD from 142.4 s to 0.7 s. Moreover, after applying the compressive strain, the band structure of ZnO MW changes and piezoelectric potential generates, which further raises the SB height, thickens the depletion region and improves photo-response properties of the detector. The dark current is reduced by about 5 orders and its on/off current ratio increased by about 6 orders, which decreases the power consumption of the detector significantly. Under the above coupling effect between piezoelectric potential and localized SBs, the recover time of the detector is further reduced to 0.1 s ultimately. This work suggests that rational integration of localized SBs and piezoelectric potential is a viable approach to get ZnO MW PDs with high on/off ratio, ultrafast response speed and low power consumption.

  20. The effect of Al segregation on Schottky barrier height and effective work function in TiAl/TiN/HfO2 gate stacks

    Science.gov (United States)

    Kim, Geun-Myeong; Oh, Young Jun; Chang, K. J.

    2016-07-01

    We perform first-principles density functional calculations to investigate the effects of Al incorporation on the p-type Schottky barrier height ≤ft({φ\\text{p}}\\right) and the effective work function for various high-k/metal gate stacks, such as TiN/HfO2 with interface Al impurities, Ti1-x Al x N/HfO2, and TiAl/TiN/HfO2. When Al atoms substitute for the interface Ti atoms at TiN/HfO2 interface, interface dipole fields become stronger, leading to the increase of {φ\\text{p}} and thereby the n-type shift of effective work function. In Ti1-x Al x N/HfO2 interface, {φ\\text{p}} linearly increases with the Al content, attributed to the presence of interface Al atoms. On the other hand, in TiAl/TiN/HfO2 interface, where Al is assumed not to segregate from TiAl to TiN, {φ\\text{p}} is nearly independent of the thickness of TiAl. Our results indicate that Al impurities at the metal/dielectric interface play an important role in controlling the effective work function, and provide a clue to understanding the n-type shift of the effective work function observed in TiAl/TiN/HfO2 gate stacks fabricated by using thegate-last process.

  1. Recrystallization effects of swift heavy {sup 209}Bi ions irradiation on electrical degradation in 4H-SiC Schottky barrier diode

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhimei; Ma, Yao; Gong, Min [Key Laboratory for Microelectronics, College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Li, Yun [Key Laboratory for Microelectronics, College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Huang, Mingmin [Key Laboratory for Microelectronics, College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Gao, Bo [Key Laboratory for Microelectronics, College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Zhao, Xin, E-mail: zhaoxin1234@scu.edu.cn [Key Laboratory for Microelectronics, College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China)

    2017-06-15

    In this paper, the phenomenon that the recrystallization effects of swift heavy {sup 209}Bi ions irradiation can partially recovery damage with more than 1 × 10{sup 10} ions/cm{sup 2} is investigated by the degradation of the electrical characteristics of 4H-SiC Schottky barrier diode (SBD) with swift heavy ion irradiation. Deep level transient spectroscopy (DLTS) and Current-Voltage (I-V) measurements clearly indicated that E{sub 0.62} defect induced by swift heavy ion irradiation, which was a recombination center, could result in the increase of reverse leakage current (I{sub R}) at fluence less than 1 × 10{sup 9} ions/cm{sup 2} and the recovery of I{sub R} at fluence more than 1 × 10{sup 10} ions/cm{sup 2} in 4H-SiC SBD. The variation tendency of I{sub R} is consisted with the change of E{sub 0.62} defect. Furthermore, it is reasonable explanation that the damage or defect formed at low fluence in SiC may be recovered by further swift heavy ion irradiation with high fluence, which is due to the melting with the ion tracks of the amorphous zones through a thermal spike and subsequent epitaxial recrystallization initiated from the neighboring crystalline regions.

  2. Enhancement of programming speed on gate-all-around poly-silicon nanowire nonvolatile memory using self-aligned NiSi Schottky barrier source/drain

    Science.gov (United States)

    Ho, Ching-Yuan; Chang, Yaw-Jen; Chiou, Y. L.

    2013-08-01

    The programming characteristics of gate-all-around silicon-oxide-nitride-oxide silicon (SONOS) nonvolatile memories are presented using NiSi/poly-Si nanowires (SiNW) Schottky barrier (SB) heterojunctions. The non-uniform thermal stress distribution on SiNW channels due to joule heating affected the carrier transport behavior. Under a high drain voltage, impact ionization was found as a large lateral field enhances carrier velocity. As gate voltage (Vg) increased, the difference in the drain current within a range of various temperature conditions can be mitigated because a high gate field lowers the SB height of a NiSi source/SiNW/NiSi drain junction to ensure efficient hot-carrier generation. By applying the Fowler-Nordheim programming voltage to the SONOS nanowire memory, the SB height (Φn = 0.34 eV) could be reduced by image force; thus, hot electrons could be injected from SB source/drain electrodes into the SiN storage node. To compare both SiNW and Si nanocrystal SONOS devices, the SB SiNW SONOS device was characterized experimentally to propose a wider threshold-voltage window, exhibiting efficient programming characteristics.

  3. Recrystallization effects of swift heavy 209Bi ions irradiation on electrical degradation in 4H-SiC Schottky barrier diode

    Science.gov (United States)

    Yang, Zhimei; Ma, Yao; Gong, Min; Li, Yun; Huang, Mingmin; Gao, Bo; Zhao, Xin

    2017-06-01

    In this paper, the phenomenon that the recrystallization effects of swift heavy 209Bi ions irradiation can partially recovery damage with more than 1 × 1010 ions/cm2 is investigated by the degradation of the electrical characteristics of 4H-SiC Schottky barrier diode (SBD) with swift heavy ion irradiation. Deep level transient spectroscopy (DLTS) and Current-Voltage (I-V) measurements clearly indicated that E0.62 defect induced by swift heavy ion irradiation, which was a recombination center, could result in the increase of reverse leakage current (IR) at fluence less than 1 × 109 ions/cm2 and the recovery of IR at fluence more than 1 × 1010 ions/cm2 in 4H-SiC SBD. The variation tendency of IR is consisted with the change of E0.62 defect. Furthermore, it is reasonable explanation that the damage or defect formed at low fluence in SiC may be recovered by further swift heavy ion irradiation with high fluence, which is due to the melting with the ion tracks of the amorphous zones through a thermal spike and subsequent epitaxial recrystallization initiated from the neighboring crystalline regions.

  4. High-barrier Schottky contact on n-type 4H-SiC epitaxial layer and studies of defect levels by deep level transient spectroscopy (DLTS)

    Science.gov (United States)

    Nguyen, Khai V.; Pak, Rahmi O.; Oner, Cihan; Mannan, Mohammad A.; Mandal, Krishna C.

    2015-08-01

    High barrier Schottky contact has been fabricated on 50 μm n-type 4H-SiC epitaxial layers grown on 350 μm thick substrate 8° off-cut towards the [11̅20] direction. The 4H-SiC epitaxial wafer was diced into 10 x 10 mm2 samples. The metal-semiconductor junctions were fabricated by photolithography and dc sputtering with ruthenium (Ru). The junction properties were characterized through current-voltage (I-V) and capacitance-voltage (C-V) measurements. Detectors were characterized by alpha spectroscopy measurements in terms of energy resolution and charge collection efficiency using a 0.1 μCi 241Am radiation source. It was found that detectors fabricated from high work function rare transition metal Ru demonstrated very low leakage current and significant improvement of detector performance. Defect characterization of the epitaxial layers was conducted by deep level transient spectroscopy (DLTS) to thoroughly investigate the defect levels in the active region. The presence of a new defect level induced by this rare transition metal-semiconductor interface has been identified and characterized.

  5. Schottky-barrier heights of metal/alpha-SiC{l_brace}0001{r_brace} interfaces by first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Shingo; Okazaki, Kazuyuki; Kohyama, Masanori [Research Institute for Ubiquitous Energy Devices, National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka 5638577 (Japan); Tamura, Tomoyuki; Ishibashi, Shoji [Research Institute for Computational Sciences, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 3058568 (Japan)

    2007-07-01

    Atomic and electronic structures and Schottky barrier heights (SBH) of multi-layer metal (=Al, Ti, Fe, Co, Ni, Cu, Pt and Au)/6H-SiC{l_brace}0001{r_brace} interfaces have been calculated by the projector augmented wave (PAW) method. The p-type SBHs of the C-terminated interfaces are smaller than those of the Si-terminated ones due to the different interface dipoles. About the dependence on the metal species, the SBHs of the Si-terminated interfaces range within a relatively narrow energy region because of more metallic characters, although those of the C-terminated ones show clearer dependence, where the SBHs decrease for the increment of metal electronegativity or work function. This inverse proportion is different from the results of monolayer metal/SiC interfaces, while consistent with experiments. All the results can be explained by the viewpoint of the interface dipole and the intrinsic relation of the band structures. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Frequency Dependent Electrical and Dielectric Properties of Au/P3HT:PCBM:F4-TCNQ/n-Si Schottky Barrier Diode

    Science.gov (United States)

    Taşçıoğlu, İ.; Tüzün Özmen, Ö.; Şağban, H. M.; Yağlıoğlu, E.; Altındal, Ş.

    2017-04-01

    In this study, poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester: 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (P3HT:PCBM:F4-TCNQ) organic film was deposited on n-type silicon (n-Si) substrate by spin coating method. The electrical and dielectric analysis of Au/P3HT:PCBM:F4-TCNQ/n-Si Schottky barrier diode was conducted by means of capacitance-voltage ( C- V) and conductance-voltage ( G/ ω- V) measurements in the frequency range of 10 kHz-2 MHz. The C- V- f plots exhibit fairly large frequency dispersion due to excess capacitance caused by the presence of interface states ( N ss). The values of N ss located in semiconductor bandgap at the organic film/semiconductor interface were calculated by Hill-Coleman method. Experimental results show that dielectric constant ( ɛ') and dielectric loss ( ɛ″) decrease with increasing frequency, whereas loss tangent (tan δ) remains nearly the same. The decrease in ɛ' and ɛ″ was interpreted by the theory of dielectric relaxation due to interfacial polarization. It is also observed that ac electrical conductivity ( σ ac) and electric modulus ( M' and M″) increase with increasing frequency.

  7. Schottky Contact of Gallium on p-Type Silicon

    Directory of Open Access Journals (Sweden)

    B.P. Modi

    2011-01-01

    Full Text Available The evolution of barrier at Schottky contact and its stabilization to value characterized by the barrier height and unambiguous measurement is still being curiously perused as they hold the key control and manufacture of tailor made Schottky devices for a host of existing and potential for future applications in electronics, optoelectronics and microwave devices. In this context, gallium – silicon Schottky diode has been fabricated and analyzed.

  8. Fabrication of Schottky barrier diodes using H{sub 2}O{sub 2}-treated non-polar ZnO (101{sup ¯}0) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kashiwaba, Yasuhiro, E-mail: kashi@sendai-nct.ac.jp [Sendai National College of Technology, Advanced Course of Information and Electronic System Engineering, 4-16-1 Ayashi-chuo, Sendai 989-3128 (Japan); Sakuma, Mio [Sendai National College of Technology, Advanced Course of Information and Electronic System Engineering, 4-16-1 Ayashi-chuo, Sendai 989-3128 (Japan); Abe, Takami; Nakagawa, Akira; Niikura, Ikuo; Kashiwaba, Yasube; Daibo, Masahiro; Osada, Hiroshi [Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan)

    2013-12-01

    Non-polar single crystal ZnO (101{sup ¯}0) substrates with hydrogen peroxide (H{sub 2}O{sub 2}) treatment were characterized and applied to Schottky barrier diodes. Formation of a ZnO{sub 2} layer with a polycrystalline structure was confirmed by 2θ scans of X-ray diffraction (XRD) measurements. Tails of the X-ray rocking curve of ZnO (101{sup ¯}0) planes were broadened with increase in H{sub 2}O{sub 2} treatment time. Grain structures were clearly observed on the surfaces of ZnO (101{sup ¯}0) substrates with H{sub 2}O{sub 2} treatment by an atomic force microscope, and the root mean square roughness of the ZnO{sub 2} surface was about 5 nm. The current density–voltage (J–V) characteristics of Pd/ZnO/Al structures using ZnO (101{sup ¯}0) substrates without H{sub 2}O{sub 2} treatment were ohmic. The J–V characteristics of Pd/ZnO{sub 2}/ZnO/Al structures using ZnO (101{sup ¯}0) substrates with H{sub 2}O{sub 2} treatment time of 5 min showed good rectifying characteristics. The ideality factor n of this diode was 1.7 and the barrier height between Pd films and the ZnO{sub 2} layer on the ZnO (101{sup ¯}0) plane was estimated to be 0.92 eV.

  9. Calculation of the Electronic Parameters of an Al/DNA/p-Si Schottky Barrier Diode Influenced by Alpha Radiation

    Directory of Open Access Journals (Sweden)

    Hassan Maktuff Jaber Al-Ta'ii

    2015-02-01

    Full Text Available Many types of materials such as inorganic semiconductors have been employed as detectors for nuclear radiation, the importance of which has increased significantly due to recent nuclear catastrophes. Despite the many advantages of this type of materials, the ability to measure direct cellular or biological responses to radiation might improve detector sensitivity. In this context, semiconducting organic materials such as deoxyribonucleic acid or DNA have been studied in recent years. This was established by studying the varying electronic properties of DNA-metal or semiconductor junctions when exposed to radiation. In this work, we investigated the electronics of aluminium (Al/DNA/silicon (Si rectifying junctions using their current-voltage (I-V characteristics when exposed to alpha radiation. Diode parameters such as ideality factor, barrier height and series resistance were determined for different irradiation times. The observed results show significant changes with exposure time or total dosage received. An increased deviation from ideal diode conditions (7.2 to 18.0 was observed when they were bombarded with alpha particles for up to 40 min. Using the conventional technique, barrier height values were observed to generally increase after 2, 6, 10, 20 and 30 min of radiation. The same trend was seen in the values of the series resistance (0.5889–1.423 Ω for 2–8 min. These changes in the electronic properties of the DNA/Si junctions could therefore be utilized in the construction of sensitive alpha particle detectors.

  10. Schottky barrier contrasts in single and bi-layer graphene contacts for MoS{sub 2} field-effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Du, Hyewon; Kim, Taekwang; Shin, Somyeong; Kim, Dahye; Seo, Sunae, E-mail: sunaeseo@sejong.ac.kr [Department of Physics, Sejong University, Seoul 143-747 (Korea, Republic of); Kim, Hakseong; Lee, Sang Wook [Divison of Quantum Phases and Devices, Department of Physics, Konkuk University, Seoul 143-701 (Korea, Republic of); Sung, Ji Ho; Jo, Moon-Ho [Center for Artificial Low-Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang 790-784 (Korea, Republic of); Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Pohang 790-784 (Korea, Republic of); Lee, Myoung Jae [Center for Artificial Low-Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang 790-784 (Korea, Republic of); Seo, David H. [Samsung Electronics Company, Limited, System LSI Division, TD Team, Gyunggi 446-711 (Korea, Republic of)

    2015-12-07

    We have investigated single- and bi-layer graphene as source-drain electrodes for n-type MoS{sub 2} transistors. Ti-MoS{sub 2}-graphene heterojunction transistors using both single-layer MoS{sub 2} (1M) and 4-layer MoS{sub 2} (4M) were fabricated in order to compare graphene electrodes with commonly used Ti electrodes. MoS{sub 2}-graphene Schottky barrier provided electron injection efficiency up to 130 times higher in the subthreshold regime when compared with MoS{sub 2}-Ti, which resulted in V{sub DS} polarity dependence of device parameters such as threshold voltage (V{sub TH}) and subthreshold swing (SS). Comparing single-layer graphene (SG) with bi-layer graphene (BG) in 4M devices, SG electrodes exhibited enhanced device performance with higher on/off ratio and increased field-effect mobility (μ{sub FE}) due to more sensitive Fermi level shift by gate voltage. Meanwhile, in the strongly accumulated regime, we observed opposing behavior depending on MoS{sub 2} thickness for both SG and BG contacts. Differential conductance (σ{sub d}) of 1M increases with V{sub DS} irrespective of V{sub DS} polarity, while σ{sub d} of 4M ceases monotonic growth at positive V{sub DS} values transitioning to ohmic-like contact formation. Nevertheless, the low absolute value of σ{sub d} saturation of the 4M-graphene junction demonstrates that graphene electrode could be unfavorable for high current carrying transistors.

  11. Design of 340 GHz 2× and 4× Sub-Harmonic Mixers Using Schottky Barrier Diodes in Silicon-Based Technology

    Directory of Open Access Journals (Sweden)

    Chao Liu

    2015-05-01

    Full Text Available This paper presents the design of terahertz 2× and 4× sub-harmonic down-mixers using Schottky Barrier Diodes fabricated in standard 0.13 μm SiGe BiCMOS technology. The 340 GHz sub-harmonic mixers (SHMs are designed based on anti-parallel-diode-pairs (APDPs. With the 2nd and 4th harmonic, local oscillator (LO frequencies of 170 GHz and 85 GHz are used to pump the two 340 GHz SHMs. With LO power of 7 dBm, the 2× SHM exhibits a conversion loss of 34.5–37 dB in the lower band (320–340 GHz and 35.5–41 dB in the upper band (340–360 GHz; with LO power of 9 dBm, the 4× SHM exhibits a conversion loss of 39–43 dB in the lower band (320–340 GHz and 40–48 dB in the upper band (340–360 GHz. The measured input 1-dB conversion gain compression point for the 2× and 4× SHMs are −8 dBm and −10 dBm at 325 GHz, respectively. The simulated LO-IF (intermediate frequency isolation of the 2× SHM is 21.5 dB, and the measured LO-IF isolation of the 4× SHM is 32 dB. The chip areas of the 2× and 4× SHMs are 330 μm × 580 μm and 550 μm × 610 μm, respectively, including the testing pads.

  12. Effect of UV lamp irradiation during oxidation of Zr/Pt/Si structure on electrical properties of Pt/ZrO{sub 2}/Pt/Si structure

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Joon Woo [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Lim, Jae-Won, E-mail: flashlim@kigam.re.kr [Mineral Resources Research Division, Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350 (Korea, Republic of); Mimura, Kouji; Uchikoshi, Masahito [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Miyazaki, Takamichi [School of Engineering, Tohoku University, Sendai 980-8579 (Japan); Isshiki, Minoru [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan)

    2010-03-15

    Metal-insulator-metal (MIM) capacitors were fabricated using ZrO{sub 2} films and the effects of structural and native defects of the ZrO{sub 2} films on the electrical and dielectric properties were investigated. For preparing ZrO{sub 2} films, Zr films were deposited on Pt/Si substrates by ion beam deposition (IBD) system with/without substrate bias voltages and oxidized at 200 deg. C for 60 min under 0.1 MPa O{sub 2} atmosphere with/without UV light irradiation ({lambda} = 193 nm, Deep UV lamp). The ZrO{sub 2}({approx}12 nm) films on Pt({approx}100 nm)/Si were characterized by X-ray diffraction pattern (XRD), field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HRTEM), capacitance-voltage (C-V) and current-voltage (I-V) measurements were carried out on MIM structures. ZrO{sub 2} films, fabricated by oxidizing the Zr film deposited with substrate bias voltage under UV light irradiation, show the highest capacitance (784 pF) and the lowest leakage current density. The active oxygen species formed by UV irradiation are considered to play an important role in the reduction of the leakage current density, because they can reduce the density of oxygen vacancies.

  13. Analysis of temperature dependent current-conduction mechanisms in Au/TiO2/n-4H-SiC (metal/insulator/semiconductor) type Schottky barrier diodes

    Science.gov (United States)

    Alialy, S.; Altındal, Ş.; Tanrıkulu, E. E.; Yıldız, D. E.

    2014-08-01

    In order to determine the effective current-conduction mechanisms in Au/TiO2/n-4H-SiC (metal-insulator semiconductor) type Schottky barrier diodes (SBDs), their current-voltage (I-V) measurements were carried out in the temperature range of 200-380 K. Some electrical parameters, such as ideality factor (n), zero-bias barrier height (BH) (ΦBo), series and shunt resistances (Rs, Rsh), were obtained as 5.09, 0.81 eV, 37.43 Ω, and 435 kΩ at 200 K and 2.68, 0.95 eV, 5.99 Ω, and 73 kΩ at 380 K, respectively. The energy density distribution profile of surface states (Nss) was extracted from the forward-bias I-V data by taking into account voltage dependent of the ideality factor (nV), effective BH (Φe), and Rs for 200, 300, and 380 K. The Ln(I) vs V plots are completely parallel in the intermediate bias voltages, which may be well explained by field emission (FE) mechanism for each temperature. On the other hand, the high value of n cannot be explained with this mechanism. Therefore, to explain the change in BH and n with temperature, ΦBo vs q/2kT plot was drawn to obtain an evidence of a Gaussian distribution (GD) of the BHs and thus the mean value of BH (Φ¯Bo) and standard deviation (σso) values were found from this plot as 1.396 eV and 0.176 V, respectively. The Φ¯Bo and Richardson constant (A*) values were found as 1.393 eV and 145.5 A.cm-2 K-2 using modified Ln(Io/T2)-(q2σs2/2k2T2) vs q/kT plot, respectively. It is clear that all of the obtained main electrical parameters were found as a strong function of temperature. These results indicated that the current conduction mechanism in Au/TiO2/n-4 H-SiC (SBD) well obey the FE and GD mechanism rather than other mechanisms.

  14. Continuous Catalytic Hydrodeoxygenation of Guaiacol over Pt/SiO2 and Pt/H-MFI-90

    DEFF Research Database (Denmark)

    Hellinger, Melanie; Baier, Sina; Mortensen, Peter Mølgaard

    2015-01-01

    Hydrodeoxygenation of guaiacol in the presence of 1-octanol was studied in a fixed-bed reactor under mild conditions (50–250 °C) over platinum particles supported on silica (Pt/SiO2) and a zeolite with framework type MFI at a Si/Al-ratio of 45 (Pt/H-MFI-90). The deoxygenation selectivity strongly...... than 30 h, probably due to carbon deposition, whereas Pt/SiO2 was more stable. The catalytic activity of the zeolite catalyst could only partly be regained by calcination in air, as some of the acidic sites were lost....

  15. Effects of sputtering power Schottky metal layers on rectifying performance of Mo-SiC Schottky contacts

    Science.gov (United States)

    Lee, Seula; Lee, Jinseon; You, Sslimsearom; Kyoung, Sinsu; Kim, Kyung Hwan

    2016-01-01

    In this study, Schottky barrier diodes based on silicon carbide with various levels of Schottky metal layer input power were prepared and characterized. In this structure, molybdenum and aluminum were employed as the Schottky metal and top electrode, respectively. Schottky metal layers were deposited with input power ranging from 30 to 210 W. Schottky metal layers and top electrodes were deposited with a thickness of 3000 Å. The Schottky barrier heights, series resistances, and ideality factor were calculated from current-voltage (I-V) curves obtained using the Cheung-Cheung and Norde methods. All deposition processes were conducted using a facing targets sputtering system. Turn on voltage was minimized when the input power was 90 W, at which point electrical characteristics were observed to have properties superior to those at other levels of input power.

  16. Electrochemical stability and postmortem studies of Pt/SiC catalysts for polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    Stamatin, Serban Nicolae; Spéder, József; Dhiman, Rajnish

    2015-01-01

    In the presented work, the electrochemical stability of platinized silicon carbide is studied. Postmortem transmission electron microscopy and X-ray photoelectron spectroscopy were used to document the change in the morphology and structure upon potential cycling of Pt/SiC catalysts. Two differen...

  17. Optimizations of Pt/SiC and W/Si multilayers for the Nuclear Spectroscopic Telescope Array

    DEFF Research Database (Denmark)

    Madsen, K. K.; Harrison, F. A.; Mao, P. H.

    2009-01-01

    The Nuclear Spectroscopic Telescope Array, NuSTAR, is a NASA funded Small Explorer Mission, SMEX, scheduled for launch in mid 2011. The spacecraft will fly two co-aligned conical approximation Wolter-I optics with a focal length of 10 meters. The mirrors will be deposited with Pt/SiC and W...

  18. Gate Modulation of Graphene-ZnO Nanowire Schottky Diode.

    Science.gov (United States)

    Liu, Ren; You, Xu-Chen; Fu, Xue-Wen; Lin, Fang; Meng, Jie; Yu, Da-Peng; Liao, Zhi-Min

    2015-05-06

    Graphene-semiconductor interface is important for the applications in electronic and optoelectronic devices. Here we report the modulation of the electric transport properties of graphene/ZnO nanowire Schottky diode by gate voltage (Vg). The ideality factor of the graphene/ZnO nanowire Schottky diode is ~1.7, and the Schottky barrier height is ~0.28 eV without external Vg. The Schottky barrier height is sensitive to Vg due to the variation of Fermi level of graphene. The barrier height increases quickly with sweeping Vg towards the negative value, while decreases slowly towards the positive Vg. Our results are helpful to understand the fundamental mechanism of the electric transport in graphene-semiconductor Schottky diode.

  19. Frequency and voltage dependence of electric and dielectric properties of Au/TiO2/n-4H-SiC (metal-insulator-semiconductor) type Schottky barrier diodes

    Science.gov (United States)

    Tanrıkulu, E. E.; Yıldız, D. E.; Günen, A.; Altındal, Ş.

    2015-09-01

    The main electrical and dielectric properties of Au/TiO2/n-4H-SiC (MIS) type Schottky barrier diodes (SBDs) have been investigated as functions of frequency and applied bias voltage. We believe that the use of high dielectric interfacial layer between metal and semiconductor can improve the performance of Schottky diodes. From the experimental data, both electrical and dielectric parameters were found as strong function of frequency and applied bias voltage. The Fermi energy level (EF), the concentration of doping donor atoms (P), barrier height (ΦB) and series resistance (Rs) values were obtained from reverse and forward bias C-V characteristics. The changes in EF and ND with frequency are considerably low. Therefore, their values were taken at about constant. The real and imaginary parts of dielectric constant (\\varepsilon \\prime , \\varepsilon \\prime\\prime ), tangent loss (tanδ), ac electrical conductivity (σac), and real and imaginary parts of electric modulus (M‧ and M″) values were also obtained from reverse and forward bias C-V and G/ω-V characteristics. In addition, the voltage dependent profiles of all these electrical and dielectric parameters were drawn for each frequency. These results confirmed that both electrical and dielectric properties of Au/TiO2/n-4H-SiC (MIS) type SBD are quite sensitive to both the frequency and applied bias voltage due to surface polarization, density distribution of interface traps (Dit), and interfacial layer.

  20. The interface states and series resistance effects on the forward and reverse bias I-V, C-V and G/{omega}-V characteristics of Al-TiW-Pd{sub 2}Si/n-Si Schottky barrier diodes

    Energy Technology Data Exchange (ETDEWEB)

    Uslu, H.; Altindal, S.; Aydemir, U. [Department of Physics, Gazi University, 06500 Ankara (Turkey); Doekme, I., E-mail: ilbilgedokme@gazi.edu.t [Science Education Department, Gazi Education Faculty, Gazi University, 06500 Ankara (Turkey); Afandiyeva, I.M. [Baku State University, Baku (Azerbaijan)

    2010-07-30

    Illumination intensity effects on the electrical characteristics of Al-TiW-Pd{sub 2}Si/n-Si Schottky structures have been investigated in this study for the first time. The electrical parameters such as ideality factor (n), zero-bias-barrier height ({Phi}{sub B0}), series resistance (R{sub s}), depletion layer width (W{sub D}) and dopping concentration (N{sub D}) of Al-TiW-Pd{sub 2}Si/n-Si Schottky barrier diodes (SBDs) have been investigated by using the forward and reverse bias current-voltage (I-V), capacitance-voltage (C-V) and conductance-voltage (G/{omega}-V) measurements in dark and under illumination conditions at room temperature. The values of C and G/{omega} increase with increasing illumination intensity due to the illumination induced electron-hole pairs in the depletion region. The density of interface states (N{sub ss}) distribution profiles as a function of (E{sub c} - E{sub ss}) was extracted from the forward I-V measurements by taking into account the bias dependence of the effective barrier heights ({Phi}{sub e}) for device in dark and under various illumination intensities. The high values of N{sub ss} were responsible for the nonideal behavior of I-V, C-V and G/{omega} characteristics. The values of R{sub s} obtained from Cheung and Nicollian methods decrease with increasing illumination intensity. The high values of n and R{sub s} have been attributed to the particular distribution of N{sub ss}, surface preparation, inhomogeneity of interfacial layer and barrier height at metal/semiconductor (M/S) interface. As a result, the characteristics of SBD are affected not only in N{sub ss} but also in R{sub s}, and these two parameters strongly influence the electrical parameters.

  1. I-V characteristics simulation of silicon carbide Ti/4H-SiC Schottky diode

    Science.gov (United States)

    Panchenko, P.; Rybalka, S.; Malakhanov, A.; Krayushkina, E.; Radkov, A.

    2016-12-01

    The simulation of current-voltage characteristics for 4H-SiC Schottky diode with Ti Schottky contact has been carried out with used of TCAD program. Obtained current-voltage characteristics has been analyzed and compared with theoretical and experimental results. It is established that the Schottky diode parameters (forward current, ideality coefficient, Schottky barrier height, breakdown voltage) obtained in proposed model are good agreement with data for such type diodes.

  2. Session 4: Low-temperature CO oxidation on Ni-Pt/SiO{sub 2} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Arenas-Alatorre, J.; Gomez-Cortes, A.; Diaz, G. [Instituto de Fisica UNAM, Mexico, D.F. (Mexico); Avalos Borja, M [Centro de Cciencias de la Materia Condensada, Ensenada, B.C. (Mexico)

    2004-07-01

    In the present study a set of Ni-Pt catalysts supported on silica have been examined as catalysts for the CO oxidation in the presence of hydrogen. The obtained results show that bimetallic Ni{sub 25}Pt{sub 75} catalyst is very active; total conversion of CO is achieved at 70 C and no significant diminution is observed at higher temperatures. Hydrogen concentration in the gas phase did not changed significantly indicating a very good selectivity towards CO oxidation. Bimetallic Ni{sub 50}Pt{sub 50} and Ni{sub 75}Pt{sub 25} catalysts showed also a good activity but the selectivity for CO oxidation decreases in favor of hydrogen oxidation at higher temperatures. It is interesting to note the performance of mono-metallic Ni/SiO{sub 2} since nickel is known to be not very active for oxidation reactions; at 120 C more than 80% of the CO is converted. On the other hand, Pt/SiO{sub 2} performance is not so good in comparison. (authors)

  3. Growth and properties of electrodeposited cobalt films on Pt/Si(1 0 0) surface

    Energy Technology Data Exchange (ETDEWEB)

    Azizi, A.; Sahari, A.; Felloussia, M.L.; Schmerber, G.; Meny, C.; Dinia, A

    2004-04-30

    In this paper, the growth, structural and magnetic properties of cobalt (Co) films electrodeposited on a Pt/Si(1 0 0) substrate have been investigated. Co films with metallic appearance were obtained from aqueous solution of 0.1 M CoSO{sub 4}, 10 mM CoCl{sub 2} as the source of metal ions and 1 M Na{sub 2}SO{sub 4} as a supporting electrolyte with 0.5 M H{sub 3}BO{sub 3} at pH 4.2. This electrochemical technique indicated a deposition peak signature of limited diffusion growth with the transition from progressive to instantaneous nucleation mechanism. The atomic force microscopy (AFM) images showed a granular structure of the electrodeposited layers. X-ray measurements (XRD) and nuclear magnetic resonance (NMR) indicate a small grain size with the presence of a mixture of Co hcp and fcc structures. The magnetic properties of the deposited films were investigated with a magnetic field in the parallel and perpendicular direction and showed that the easy magnetization axis is in the plane.

  4. Scaling of nano-Schottky-diodes

    NARCIS (Netherlands)

    Smit, G.D.J.; Rogge, S.; Klapwijk, T.M.

    2002-01-01

    A generally applicable model is presented to describe the potential barrier shape in ultrasmall Schottky diodes. It is shown that for diodes smaller than a characteristic length lc (associated with the semiconductor doping level) the conventional description no longer holds. For such small diodes th

  5. Investigation of the magnetic domain structure of(PtCoPt)/Si multilayers by magnetic force microscopy

    Institute of Scientific and Technical Information of China (English)

    张臻蓉; 刘洪; 韩宝善

    2002-01-01

    The domain structure of (PtCoPt)/Si multilayers in the dc demagnetized state has been investigated by magnetic force microscopy. The domain structure is found to change dramatically as the thickness of the non-magnetic Si sublayer(tsi) increases. Together with the analysis of magnetic properties, the variation of the domain period indicates that the domain wall energy decreases. Using the model developed by Draaisma and de Jonge, the domain wall energy is obtained.

  6. Thermal stability dependence on the stacking order and thickness ratio of the CoPt -TiO2/CoCrPt-SiO2 stacked media

    Science.gov (United States)

    Park, S. H.; Lee, T. D.; Kong, S. H.; Yoon, S. Y.; Lee, H. S.; Kim, H. J.; Oh, H. S.

    2008-04-01

    Thermal stability of the present CoCrPt -SiO2 media becomes a more critical issue as recording density steadily increases. In the present study, thermal stability of the stacked media composed of high Ku CoPt -TiO2 and normal Ku CoCrPt -SiO2 was studied by changing stacking order and thickness of each layer while keeping a constant total thickness. When the CoPt -TiO2 layer was placed under the CoCrPt -SiO2 layer, negative nucleation field and coercivity increased much more than those of the reverse stacking case. Thermal stability of the CoPt -TiO2 bottom group was superior to that of the CoCrPt -SiO2 bottom group when measured by a spin stand.

  7. Supersensitive, Fast-Response Nanowire Sensors by Using Schottky Contacts

    KAUST Repository

    Hu, Youfan

    2010-05-31

    A Schottky barrier can be formed at the interface between a metal electrode and a semiconductor. The current passing through the metal-semiconductor contact is mainly controlled by the barrier height and barrier width. In conventional nanodevices, Schottky contacts are usually avoided in order to enhance the contribution made by the nanowires or nanotubes to the detected signal. We present a key idea of using the Schottky contact to achieve supersensitive and fast response nanowire-based nanosensors. We have illustrated this idea on several platforms: UV sensors, biosensors, and gas sensors. The gigantic enhancement in sensitivity of up to 5 orders of magnitude shows that an effective usage of the Schottky contact can be very beneficial to the sensitivity of nanosensors. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Schottky contacts to In2O3

    Directory of Open Access Journals (Sweden)

    H. von Wenckstern

    2014-04-01

    Full Text Available n-type binary compound semiconductors such as InN, InAs, or In2O3 are especial because the branch-point energy or charge neutrality level lies within the conduction band. Their tendency to form a surface electron accumulation layer prevents the formation of rectifying Schottky contacts. Utilizing a reactive sputtering process in an oxygen-containing atmosphere, we demonstrate Schottky barrier diodes on indium oxide thin films with rectifying properties being sufficient for space charge layer spectroscopy. Conventional non-reactive sputtering resulted in ohmic contacts. We compare the rectification of Pt, Pd, and Au Schottky contacts on In2O3 and discuss temperature-dependent current-voltage characteristics of Pt/In2O3 in detail. The results substantiate the picture of oxygen vacancies being the source of electrons accumulating at the surface, however, the position of the charge neutrality level and/or the prediction of Schottky barrier heights from it are questioned.

  9. Influence of intergranular exchange coupling on the magnetization dynamics of CoCrPt:SiO{sub 2} granular media

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, R.; Schmidt, H. [School of Engineering, University of California-Santa Cruz, 1156 High Street, Santa Cruz, California 95064 (United States); Tibus, S. [Department of Physics, University of Konstanz, D-78457 Konstanz (Germany); Institute of Physics, Chemnitz University of Technology, Reichenhainer Str. 70, 09126 Chemnitz (Germany); Springer, F. [Department of Physics, University of Konstanz, D-78457 Konstanz (Germany); Fassbender, J. [Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, D-01314 Dresden (Germany); Rohrmann, H. [OC Oerlikon Balzers AG, LI-9496 Balzers (Liechtenstein); Albrecht, M. [Institute of Physics, Chemnitz University of Technology, Reichenhainer Str. 70, 09126 Chemnitz (Germany)

    2012-08-01

    We investigate the effect of Co{sup +} irradiation on the magnetization dynamics of CoCrPt:SiO{sub 2} granular media. Increasing irradiation levels reduce the saturation magnetization and effective anisotropy, which decrease the intrinsic magnetization precession frequency. Furthermore, increasing intergranular exchange coupling results in a qualitative change in the behavior of the magnetic material from a collection of individual grains to a homogeneous thin film, as evidenced in both the switching behavior and dynamics. The frequency change cannot be explained by single crystal macrospin modeling, and can only be reproduced by the inclusion of the dipolar effects and anisotropy distribution inherent in a granular medium.

  10. Richardson-Schottky transport mechanism in ZnS nanoparticles

    Science.gov (United States)

    Ali, Hassan; Khan, Usman; Rafiq, M. A.; Falak, Attia; Narain, Adeela; Jing, Tang; Xu, Xiulai

    2016-05-01

    We report the synthesis and electrical transport mechanism in ZnS semiconductor nanoparticles. Temperature dependent direct current transport measurements on the compacts of ZnS have been performed to investigate the transport mechanism for temperature ranging from 300 K to 400 K. High frequency dielectric constant has been used to obtain the theoretical values of Richardson-Schottky and Poole-Frenkel barrier lowering coefficients. Experimental value of the barrier lowering coefficient has been calculated from conductance-voltage characteristics. The experimental value of barrier lowering coefficient βexp lies close to the theoretical value of Richardson-Schottky barrier lowering coefficient βth,RS showing Richardson-Schottky emission has been responsible for conduction in ZnS nanoparticles for the temperature range studied.

  11. Richardson-Schottky transport mechanism in ZnS nanoparticles

    Directory of Open Access Journals (Sweden)

    Hassan Ali

    2016-05-01

    Full Text Available We report the synthesis and electrical transport mechanism in ZnS semiconductor nanoparticles. Temperature dependent direct current transport measurements on the compacts of ZnS have been performed to investigate the transport mechanism for temperature ranging from 300 K to 400 K. High frequency dielectric constant has been used to obtain the theoretical values of Richardson-Schottky and Poole-Frenkel barrier lowering coefficients. Experimental value of the barrier lowering coefficient has been calculated from conductance-voltage characteristics. The experimental value of barrier lowering coefficient βexp lies close to the theoretical value of Richardson-Schottky barrier lowering coefficient βth,RS showing Richardson-Schottky emission has been responsible for conduction in ZnS nanoparticles for the temperature range studied.

  12. Eosin Y/Pt/SiO2催化剂光催化还原水制氢%Photocatalytic Reduction of Water to Hydrogen over Eosin Y/Pt/SiO2 Catalysts

    Institute of Scientific and Technical Information of China (English)

    张晓杰; 汤长青; 靳治良; 吕功煊; 李树本

    2011-01-01

    A novel efficient photoscatalytic system Eosin Y/Pt/SiO2 for photocatalytic reduction of water to hydrogen under visible light irradiation was constructed.The effects of parameters, such as the surface physical property of SiO2 (i.e., specific surface area), method of mixing Eosin Y and SiO2, and light intensity on catalyst properties for hydrogen evolution were investigated systemically.With increase of SiO2 specific surface area, the rate of hydrogen evolution increased.Either over high or low intensive irradiation is detrimental to obtain high quantum efficiency for hydrogen evolution.Compared to the Eosin Y adsorbed on SiO2 by an impregnation method, the composite system in which Eosin Y mixed with SiO2 physically in situ displayed higher rate and superior stability of hydrogen evolution.%构建了具有较高可见光还原水制氢性能的Eosin Y/Pt/SiO2催化体系,详细考察了二氧化硅性质、曙红Y 与二氧化硅的混合方式以及光照强度等因素对光敏化催化剂制氢性能的影响.实验结果表明:二氧化硅的比表面积增大,析氧速率随之提高;光照强度过高或过低都不利于提高光量子效率;与曙红Y浸渍法吸附在二氧化硅表面制备的催化剂相比,原位物理混合制备的催化剂光敏化析氢速率和稳定性均有显著提高.

  13. Stable dielectric response of low-loss aromatic polythiourea thin films on Pt/SiO2 substrate

    Science.gov (United States)

    Eršte, A.; Fulanović, L.; Čoga, L.; Lin, M.; Thakur, Y.; Zhang, Q. M.; Bobnar, V.

    2016-03-01

    We have investigated dielectric properties of aromatic polythiourea (ArPTU, a polar polymer containing high dipolar moments with very low defect levels) thin films that were developed on Pt/SiO2 substrate. The detected response is compared to the response of commercially available polymers, such as high density polyethylene (HDPE) and polypropylene (PP), which are at present used in foil capacitors. Stable values of the dielectric constant ɛ‧≈5 (being twice higher than in HDPE and PP) over broad temperature and frequency ranges and dielectric losses as low as in commercial systems suggest ArPTU as a promising candidate for future use in a variety of applications.

  14. Deep-level transient spectroscopy on an amorphous InGaZnO4 Schottky diode

    NARCIS (Netherlands)

    Chasin, A.; Simoen, E.; Bhoolokam, A.; Nag, M.; Genoe, J.; Gielen, G.; Heremans, P.

    2014-01-01

    The first direct measurement is reported of the bulk density of deep states in amorphous IGZO (indium-gallium-zinc oxide) semiconductor by means of deep-level transient spectroscopy (DLTS). The device under test is a Schottky diode of amorphous IGZO semiconductor on a palladium (Pd) Schottky-barrier

  15. Synthesis and Characterization of Monodisperse Metallodielectric SiO2@Pt@SiO2 Core-Shell-Shell Particles.

    Science.gov (United States)

    Petrov, Alexey; Lehmann, Hauke; Finsel, Maik; Klinke, Christian; Weller, Horst; Vossmeyer, Tobias

    2016-01-26

    Metallodielectric nanostructured core-shell-shell particles are particularly desirable for enabling novel types of optical components, including narrow-band absorbers, narrow-band photodetectors, and thermal emitters, as well as new types of sensors and catalysts. Here, we present a facile approach for the preparation of submicron SiO2@Pt@SiO2 core-shell-shell particles. As shown by transmission and scanning electron microscopy, the first steps of this approach allow for the deposition of closed and almost perfectly smooth platinum shells onto silica cores via a seeded growth mechanism. By choosing appropriate conditions, the shell thickness could be adjusted precisely, ranging from ∼3 to ∼32 nm. As determined by X-ray diffraction, the crystalline domain sizes of the polycrystalline metal shells were ∼4 nm, regardless of the shell thickness. The platinum content of the particles was determined by atomic absorption spectroscopy and for thin shells consistent with a dense metal layer of the TEM-measured thickness. In addition, we show that the roughness of the platinum shell strongly depends on the storage time of the gold seeds used to initiate reductive platinum deposition. Further, using polyvinylpyrrolidone as adhesion layer, it was possible to coat the metallic shells with very homogeneous and smooth insulating silica shells of well-controlled thicknesses between ∼2 and ∼43 nm. After depositing the particles onto silicon substrates equipped with interdigitated electrode structures, the metallic character of the SiO2@Pt particles and the insulating character of the SiO2 shells of the SiO2@Pt@SiO2 particles were successfully demonstrated by charge transport measurements at variable temperatures.

  16. Fabrication and characterization of gridded Pt/SiO{sub 2}/Si MOS structure for hydrogen and hydrogen sulphide sensing

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vinod, E-mail: vkchaudhary.rs.ece@iitbhu.ac.in [Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, Uttar Pradesh (India); Sunny [Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, Uttar Pradesh (India); Rawal, Ishpal [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Mishra, V.N.; Dwivedi, R.; Das, R.R. [Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, Uttar Pradesh (India)

    2014-08-01

    A gridded gate Pt/SiO{sub 2}/Si MOS capacitor has been fabricated for detection of Hydrogen (H{sub 2}) and Hydrogen Sulphide (H{sub 2}S) gases. The MOS device was fabricated on P-type Si <100> (1–6 Ω cm) wafer with thermal oxide layer of thickness about 100 Å, whereas, Platinum (Pt) gate of ∼350 Å was deposited by thermal evaporation technique. The C–V (capacitance vs voltage) and G–V (conductance vs voltage) measurements have been performed for the evaluation of gas sensing behavior of fabricated MOS capacitor structure in H{sub 2} (250–4000 ppm) and H{sub 2}S (1000–6000 ppm) gases at both room and 120 °C temperatures, in a closed chamber in air atmosphere. It has been observed that the value of capacitance decreases with increase in gas concentration. The fabricated MOS capacitor sensor has shown better sensitivity towards H{sub 2} (88.6%) at room temperature (∼25 °C) as compared to (∼45%) at 120 °C. Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) studies have revealed the porous nature of the deposited metal film. The side wall diffusion, spillover of Hydrogen into oxide layer, increase in fixed oxide charge density, increase in surface area caused by gridded structure, the formation of dipole layer and change in interface state density on gas exposure, may be the mechanisms of gas sensing for improved sensitivity of the fabricated MOS device. - Highlights: • Pt gate gridded MOS structure (Pt/SiO{sub 2}/Si) has been fabricated first time. • The fabricated MOS sensor was first time tested for hydrogen and hydrogen sulphide gases. • The sensitivity of the gridded structure is found greater than conventional structures.

  17. Current voltage analysis and band diagram of Ti/TiO{sub 2} nanotubes Schottky junction

    Energy Technology Data Exchange (ETDEWEB)

    Mini, P.A.; Sherine, Alex; Shalumon, K.T.; Balakrishnan, Avinash; Nair, S.V.; Subramanian, K.R.V. [Amrita Vishwa Vidyapeetham (University), Amrita Centre for Nanosciences and Molecular Medicine, Kochi (India)

    2012-08-15

    Here, we report on how the energy band diagram of a nanostructured semiconductor- metal interface aligns in accordance with semiconductor morphology. Electrochemically, titanium metal is anodized to form titanium dioxide nanotubes, which forms a junction with the free Ti substrate and this junction forms a natural Schottky barrier. With reduced dimensionality of the nanotube structures (lower wall thickness), we have observed band edge movements and band gap quantum confinement effects and lowering of the Schottky barrier. These results were corroborated with the help of cyclic voltammetry, ultraviolet-visible spectrometry, and impedance analysis. Current voltage analysis of the Schottky barrier showed a lowering of the barrier (by 25 %) with reducing dimensionality of the nanotube structures. At externally applied voltages higher than the Schottky barrier, charges can travel along the nanotubes and reside at an interface between the nanotubes and a high-{kappa} dielectric. This property was utilized to develop high surface area solid-state capacitors. (orig.)

  18. Current voltage analysis and band diagram of Ti/TiO2 nanotubes Schottky junction

    Science.gov (United States)

    Mini, P. A.; Sherine, Alex; Shalumon, K. T.; Balakrishnan, Avinash; Nair, S. V.; Subramanian, K. R. V.

    2012-08-01

    Here, we report on how the energy band diagram of a nanostructured semiconductor- metal interface aligns in accordance with semiconductor morphology. Electrochemically, titanium metal is anodized to form titanium dioxide nanotubes, which forms a junction with the free Ti substrate and this junction forms a natural Schottky barrier. With reduced dimensionality of the nanotube structures (lower wall thickness), we have observed band edge movements and band gap quantum confinement effects and lowering of the Schottky barrier. These results were corroborated with the help of cyclic voltammetry, ultraviolet-visible spectrometry, and impedance analysis. Current voltage analysis of the Schottky barrier showed a lowering of the barrier (by 25 %) with reducing dimensionality of the nanotube structures. At externally applied voltages higher than the Schottky barrier, charges can travel along the nanotubes and reside at an interface between the nanotubes and a high- κ dielectric. This property was utilized to develop high surface area solid-state capacitors.

  19. Fluorine plasma treatment induced deep level traps and their effect on current transportation in Al0.83In0.17N/AlN/GaN Schottky barrier diodes

    Science.gov (United States)

    Xiang, Yong; Yu, Tongjun; Ji, Cheng; Cheng, Yutian; Yang, Xuelin; Kang, Xiangning; Shen, Bo; Zhang, Guoyi

    2016-08-01

    The deep level traps and the electrical properties of fluorine plasma treated (F-treated) and non-treated Al0.83In0.17N/AlN/GaN Schottky barrier diodes (SBDs) were investigated by the temperature-dependent current-voltage (I-V) and deep level transient spectroscopy (DLTS) measurements. Three deep level traps were detected in the SBD after F-treatment at ~E c  -  0.17 eV, ~E c  -  0.27 eV and ~E c  -  1.14 eV. One of the deep level traps at ~E c  -  1.14 eV is mainly located in the Al0.83In0.17N barrier layer with a captured cross section (σ) of ~6.50  ×  10-18 cm2. This F-related deep level trap has 3-4 orders of magnitude of the larger σ and ~0.46 eV greater active energy than that of the dislocation-related one at ~E c  -  0.68 eV with σ of ~1.92  ×  10-21 cm2. Meanwhile, the leakage current of F-treated SBD at  -5 V is reduced by ~2 orders of magnitude compared with that of the non-treated one. This leakage current reduction is mainly attributed to the increase of the Poole-Frenkel emission barrier height from ~0.09 eV in non-treated SBD to ~0.46 eV in the F-treated one. It is believed that the main reverse current transportation is the Poole-Frenkel emission from the F-related deep level trap states into the continuum states of the dislocations in F-treated Al0.83In0.17N/AlN/GaN SBD.

  20. Current transport mechanism of p-GaN Schottky contacts

    Science.gov (United States)

    Shiojima, Kenji; Sugahara, Tomoya; Sakai, Shiro

    2000-12-01

    Transient measurements of I-V and depletion layer capacitance were conducted to clarify the leaky current flow mechanism in Ni Schottky contacts formed on Mg-doped p-GaN. We found that carrier capture and emission from acceptor-like deep level defects cause depletion layer width (Wdep) to vary significantly. Upon ionization of the defects by white light, which results in small Wdep, current can go through the Schottky barrier and a leaky I-V curve is observed. Upon filling by current injection, Wdep becomes larger and the large original Schottky barrier height is seen. The time constant of carrier emission is as long as 8.3×103 min.

  1. Comparison Study of Super junction and Floating Junction Schottky Barrier Diodes%超结与浮结型肖特基势垒二极管的比较研究

    Institute of Scientific and Technical Information of China (English)

    曹琳; 蒲红斌; 陈治明

    2011-01-01

    对浮结型及超结型肖特基势垒二极管静态及动态特性进行了解析及模拟.静态特性通过解析击穿电压与导通电阻之间的关系得到.反向恢复特性通过二极管电容随反向电压变化关系解释,商用混合模拟器MEDICI模拟结果表明浮结结构具有软恢复特性,软度因子为0.949.超结结构恢复特性较硬,软度因子为0.7807.当考虑这两种耐压结构时,必须权衡静态及动态之间的关系.%In this paper,the static and dynamic characteristics of superjunction and floating junction Schottky barrier diodes were analyzed and simulated.Work principles of the device were reported,tradeoff between breakdown voltage and specific resistance was theoretically calculated and compared.The reverse recovery characteristics were analyzed by diode capacitance as function of diode reverse voltage,the mixed circuit-device simulator MEDICI shown that floating junction had softness factor 0.949,while hard recovery characteristics were obtain for superjunction structure with softness factor 0.780 7.Trade-off must be made when static and dynamic performance is considered.

  2. La3+、Cu2+、Fe3+/TiO2对金属-半导体表面肖特基势垒的影响%Study on the influence of La3+,Cu2+,Fe3+/TiO2 on Schottky barrier on the surface of metal-semiconductors

    Institute of Scientific and Technical Information of China (English)

    康华; 李桂春; 单志强

    2009-01-01

    分析了金属-半导体表面的接触机理及肖特基势垒的形成,探讨了离子掺杂行为对势垒的影响机理,研究了光生载流子的迁移对TiO2半导体复合材料光催化活性的影响.结果表明,不同金属基体材料对表面势垒高度的影响程度不同,同掺杂离子的表面态对金属-半导体接触的影响也有差别,离子可以改变半导体功函数,La3+、Cu2+和Fe3+在同一浓度掺杂,对半导体的功函数影响不同,使载体和离子对电子和空穴捕获能力有所差异.%The mechanisms for contact between metal and semiconductor surface and formation of Schott-ky barriers were discussed. The influence of ions-doping on the barriers and effects of e-h+ transfer on photocatalytic activity of TiO2 films were studied. The results indicated that different metal substrates had different influence on Schottky barriers;doping ions changed work function of the semiconductor; different doping ions metal with the same concentration changed work function of the semiconductor to different extent, thus changed Schottky barriers, resulting in different photocatalytic activity of TiO2 films.

  3. Ni based planar Schottky diodes on gallium nitride (GaN) grown on sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Menard, Olivier [Universite de Francois Rabelais, Laboratoire de Microelectronique de Puissance, 16 Rue Pierre et Marie Curie, BP7155, 37071 Tours (France); STMicroelectronics, 16 Rue Pierre et Marie Curie, BP7155, 37071 Tours (France); Cayrel, Frederic; Alquier, Daniel [Universite de Francois Rabelais, Laboratoire de Microelectronique de Puissance, 16 Rue Pierre et Marie Curie, BP7155, 37071 Tours (France); Collard, Emmanuel [STMicroelectronics, 16 Rue Pierre et Marie Curie, BP7155, 37071 Tours (France)

    2010-01-15

    In this work, Schottky barrier diodes (SBD), made using lift-off process, were realized on low doped n-type GaN grown by MOCVD. Schottky to Schottky structures were first realized, allowing to select convenient process parameters that reduce the leakage current, such as surface cleaning, thickness of the metallic contact and annealing time or temperature. Then, planar Schottky diodes were patterned and characterized to extract barrier height and ideality factor. Results show that good rectifying behaviour can be obtained with a 300nm thick Ni Schottky contact annealed in RTA at 450 C during 3 min under Argon. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Gigantic Enhancement in Sensitivity Using Schottky Contacted Nanowire Nanosensor

    KAUST Repository

    Wei, Te-Yu

    2009-12-09

    A new single nanowire based nanosensor is demonstrated for illustrating its ultrahigh sensitivity for gas sensing. The device is composed of a single ZnO nanowire mounted on Pt electrodes with one end in Ohmic contact and the other end in Schottky contact. The Schottky contact functions as a "gate" that controls the current flowing through the entire system. By tuning the Schottky barrier height through the responsive variation of the surface chemisorbed gases and the amplification role played by the nanowire to Schottky barrier effect, an ultrahigh sensitivity of 32 000% was achieved using the Schottky contacted device operated in reverse bias mode at 275 °C for detection of 400 ppm CO, which is 4 orders of magnitude higher than that obtained using an Ohmic contact device under the same conditions. In addition, the response time and reset time have been shortened by a factor of 7. The methodology and principle illustrated in the paper present a new sensing mechanism that can be readily and extensively applied to other gas sensing systems. © 2009 American Chemical Society.

  5. Silicon Schottky photovoltaic diodes for solar energy conversion

    Science.gov (United States)

    Anderson, W. A.

    1975-01-01

    Various factors in Schottky barrier solar cell fabrication are evaluated in order to improve understanding of the current flow mechanism and to isolate processing variables that improve efficiency. Results of finger design, substrate resistivity, surface finishing and activation energy studies are detailed. An increased fill factor was obtained by baking of the vacuum system to remove moisture.

  6. A model to non-uniform Ni Schottky contact on SiC annealed at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Pristavu, G.; Brezeanu, G.; Badila, M. [Electronics, Telecommunications and Information Technology, University Politehnica Bucharest, Bucharest 061071 (Romania); Pascu, R. [Electronics, Telecommunications and Information Technology, University Politehnica Bucharest, Bucharest 061071 (Romania); National Institute for Research and Development in Microtechnologies, Erou Iancu Nicolae Street 126A, 077190 Bucharest (Romania); Danila, M. [National Institute for Research and Development in Microtechnologies, Erou Iancu Nicolae Street 126A, 077190 Bucharest (Romania); Godignon, P. [Centro Nacional de Microelectronica, C/del Tillers, Campus Universitat Autònoma de Barcelona, 08193 Barcelona (Spain)

    2015-06-29

    Ni Schottky contacts on SiC have a nonideal behavior, with strong temperature dependence of the electrical parameters, caused by a mixed barrier on the contact area and interface states. A simple analytical model that establishes a quantitative correlation between Schottky contact parameter variation with temperature and barrier height non-uniformity is proposed. A Schottky contact surface with double Schottky barrier is considered. The main model parameters are the lower barrier (Φ{sub Bn,l}) and a p factor which quantitatively evaluates the barrier non-uniformity on the Schottky contact area. The model is validated on Ni/4H-SiC Schottky contacts, post metallization sintered at high temperatures. The measured I{sub F}–V{sub F}–T characteristics, selected so as not to be affected by interface states, were used for model correlation. An inhomogeneous double Schottky barrier (with both nickel silicide and Ni droplets at the interface) is formed by a rapid thermal annealing (RTA) at 750 °C. High values of the p parameter are obtained from samples annealed at this temperature, using the proposed model. A significant improvement in the electrical properties occurs following RTA at 800 °C. The expansion of the Ni{sub 2}Si phase on the whole contact area is evinced by an X-Ray diffraction investigation. In this case, the p factor is much lower, attesting the uniformity of the contact. The model makes it possible to evaluate the real Schottky barrier, for a homogenous Schottky contact. Using data measured on samples annealed at 800 °C, a true barrier height of around 1.73 V has been obtained for Ni{sub 2}Si/4H-SiC Schottky contacts.

  7. A model to non-uniform Ni Schottky contact on SiC annealed at elevated temperatures

    Science.gov (United States)

    Pristavu, G.; Brezeanu, G.; Badila, M.; Pascu, R.; Danila, M.; Godignon, P.

    2015-06-01

    Ni Schottky contacts on SiC have a nonideal behavior, with strong temperature dependence of the electrical parameters, caused by a mixed barrier on the contact area and interface states. A simple analytical model that establishes a quantitative correlation between Schottky contact parameter variation with temperature and barrier height non-uniformity is proposed. A Schottky contact surface with double Schottky barrier is considered. The main model parameters are the lower barrier (ΦBn,l) and a p factor which quantitatively evaluates the barrier non-uniformity on the Schottky contact area. The model is validated on Ni/4H-SiC Schottky contacts, post metallization sintered at high temperatures. The measured IF-VF-T characteristics, selected so as not to be affected by interface states, were used for model correlation. An inhomogeneous double Schottky barrier (with both nickel silicide and Ni droplets at the interface) is formed by a rapid thermal annealing (RTA) at 750 °C. High values of the p parameter are obtained from samples annealed at this temperature, using the proposed model. A significant improvement in the electrical properties occurs following RTA at 800 °C. The expansion of the Ni2Si phase on the whole contact area is evinced by an X-Ray diffraction investigation. In this case, the p factor is much lower, attesting the uniformity of the contact. The model makes it possible to evaluate the real Schottky barrier, for a homogenous Schottky contact. Using data measured on samples annealed at 800 °C, a true barrier height of around 1.73 V has been obtained for Ni2Si/4H-SiC Schottky contacts.

  8. High-temperature current conduction through three kinds of Schottky diodes

    Institute of Scientific and Technical Information of China (English)

    Li Fei; Zhang Xiao-Ling; Duan Yi; Xie Xue-Song; Lü Chang-Zhi

    2009-01-01

    Fundamentals of the Schottky contacts and the high-temperature current conduction through three kinds of Schottky diodes are studied. N-Si Schottky diodes, GaN Schottky diodes and AlGaN/GaN Schottky diodes are investigated by I-V-T measurements ranging from 300 to 523 K. For these Schottky diodes, a rise in temperature is accompanied with an increase in barrier height and a reduction in ideality factor. Mechanisms are suggested, including thermionic emission, field emission, trap-assisted tunnelhng and so on. The most remarkable finding in the present paper is that these three kinds of Sehottky diodes are revealed to have different behaviours of high-temperature reverse currents. For the n-Si Sehottky diode, a rise in temperature is accompanied by an increase in reverse current. The reverse current of the GaN Schottky diode decreases first and then increases with rising temperature. The AIGaN/GaN Schottky diode has a trend opposite to that of the GaN Schottky diode, and the dominant mechanisms are the effects of the piezoelectric polarization field and variation of two-dimensional electron gas charge density.

  9. SCHOTTKY MEASUREMENTS DURING RHIC 2000.

    Energy Technology Data Exchange (ETDEWEB)

    CAMERON,P.; CUPOLO,J.; DEGEN,C.; HAMMONS,L.; KESSELMAN,M.; LEE,R.; MEYER,A.; SIKORA,R.

    2001-06-18

    The 2GHz Schottky system was a powerful diagnostic during RHIC 2000 commissioning. A continuous monitor without beam excitation, it provided betatron tune, chromaticity, momentum spread relative emittance, and synchrotron tune. It was particularly useful during transition studies. In addition, a BPM was resonated at 230MHz for Schottky measurements.

  10. Temperature dependence of current–voltage characteristics of Au/-GaAs epitaxial Schottky diode

    Indian Academy of Sciences (India)

    R Singh; S K Arora; Renu Tyagi; S K Agarwal; D Kanjilal

    2000-12-01

    The influence of temperature on current–voltage (–) characteristics of Au/-GaAs Schottky diode formed on -GaAs epitaxial layer grown by metal organic chemical vapour deposition technique has been investigated. The dopant concentration in the epitaxial layer is 1 × 1016 cm−3 . The change in various parameters of the diode like Schottky barrier height (SBH), ideality factor and reverse breakdown voltage as a function of temperature in the range 80−300 K is presented. The variation of apparent Schottky barrier height and ideality factor with temperature has been explained considering lateral inhomogeneities in the Schottky barrier height in nanometer scale lengths at the metal–semiconductor interface.

  11. Effects of Ru Seed Layer on Structural Properties of CoCrPt-SiO2 Perpendicular Media%Ru籽晶层对CoCrPt-SiO2垂直记录层形貌及结构的影响

    Institute of Scientific and Technical Information of China (English)

    张俊敏; 王传军; 沈月; 谭志龙; 毕珺; 闻明; 周悓田

    2015-01-01

    CoCrPt-SiO2 perpendicular recording films were prepared by the magnetron sputtering with a series of Ru films as the seed layer. The microstructure of Ru seed layers and their effects on the grain size, roughness and surface morphology of CoCrPt-SiO2 granular films were also investigated. It was found that the microstructure of seed layer obviously affected the structure and grain isolation of recording layers. The grain size and roughness of CoCrPt-SiO2 recording layer increased with the increase of the thickness of Ru seed layer. The thin and rough Ru seed layer could be used for the high-density magnetic recording media, but the Ru seed layer with a proper thickness of 70 nm facilitated a perfect isolation, and consequently excellent magnetic properties could be acquired for the final products.%采用磁控溅射方法,制备了惣不同厚度Ru薄膜为籽晶层的CoCrPt-SiO2垂直磁记录薄膜。利用原子力显微镜(AFM)、透射电镜(TEM)分析 Ru 薄膜的结构和形貌,并悁究了其结构对CoCrPt-SiO2薄膜表面形貌、粗糙度及结构的愝响。结果表明,CoCrPt-SiO2记录层的晶粒尺寸和粗糙度均随着 Ru 籽晶层厚度的增加而增加,薄而粗糙的籽晶层适合于高密度磁记录介质。对于CoCrPt-SiO2记录层晶粒的优化,厚度为70 nm的Ru籽晶层有利于记录层薄膜晶粒的完全隔离,从而提高了磁记录性能。

  12. Terahertz pulse detection by the GaAs Schottky diodes

    Science.gov (United States)

    Laperashvili, Tina; Kvitsiani, Orest; Imerlishvili, Ilia; Laperashvili, David

    2010-06-01

    We present the results of experimental studies of physical properties of the detection process of GaAs Schottky diodes for terahertz frequency radiation. The development of technology in the THz frequency band has a rapid progress recently. Considered as an extension of the microwave and millimeter wave bands, the THz frequency offers greater communication bandwidth than is available at microwave frequencies. The Schottky barrier contact has an important role in the operation of many GaAs devices. GaAs Schottky diodes have been the primary nonlinear device used in millimeter and sub millimeter wave detectors and receivers. GaAs Schottky diodes are especially interesting due to their high mobility transport characteristics, which allows for a large reduction of the resistance-capacitance (RC) time constant and thermal noise. In This work are investigated the electrical and photoelectric properties of GaAs Schottky diodes. Samples were obtained by deposition of different metals (Au, Ni, Pt, Pd, Fe, In, Ga, Al) on semiconductor. For fabrication metal-semiconductor (MS) structures is used original method of metal electrodepositing. In this method electrochemical etching of semiconductor surface occurs just before deposition of metal from the solution, which contains etching material and metal ions together. For that, semiconductor surface cleaning processes and metal deposition carries out in the same technological process. In the experiments as the electrolyte was used aqueous solution of chlorides. Metal deposition was carried out at room temperature.

  13. Capacitance-frequency Spectrum Characterization of Organics/Metal Schottky Diodes

    Institute of Scientific and Technical Information of China (English)

    GUO Wen-ge; ZHANG Yan-cao; ZHANG Shou-gang

    2006-01-01

    An organics/metal Schottky diode is fabricated using 3, 4∶9, 10-perylenetetracarboxylic-dianhydride(PTCDA) thin film sandwiched between ITO and Au by simple thermal evaporation technique. The current-voltage(I-V) characteristics are investigated at room temperature in open air. The results show the rectification ratio is in excess of 100. From the capacitance-frequency(C-f) and capacitance-voltage(C-V) measurements, the Schottky barrier height between 0.2~0.3 eV is obtained according to standard Schottky theory.

  14. Fabrication of Ni/Ti/Al Schottky contact to n-type 4H-SiC under various annealing conditions

    Science.gov (United States)

    Yousuf Zaman, M.; Ferrero, S.; Perrone, D.; Scaltrito, L.; Shahzad, N.; Pugliese, D.

    2013-06-01

    Forward I-V characteristics of a silicon carbide Schottky diode, with triple layer metallization Ni/Ti/Al as Schottky contact, are presented. Effects of different annealing conditions on the Schottky barrier height and ideality factor are discussed. The diodes were annealed in inert Ar atmosphere for 30 minutes at temperatures ranging from 600 °C to 800 °C. The ideality factors of the four diodes, chosen out of 20 diodes, range from 1.02 to 1.13 and the Schottky barrier heights range from 1.47 eV to 3.17 eV.

  15. Double exponential I-V characteristics and double Gaussian distribution of barrier heights in (Au/Ti)/Al2O3/ n-GaAs (MIS)-type Schottky barrier diodes in wide temperature range

    Science.gov (United States)

    Güçlü, Çiğdem Ş.; Özdemir, Ahmet Faruk; Altindal, Şemsettin

    2016-12-01

    In this study, current conduction mechanisms of the sample (Au/Ti)/Al2O3/ n-GaAs were investigated in detail using current-voltage (I-V) measurements in the temperature range of 80-380 K. The semilogarithmic I-V plots reveal two distinct linear regions with different slopes between 0.07-0.30 and 0.30-0.69 V which are called as Region I (RI) and Region II (RII), respectively. The ideality factor ( n) and zero-bias barrier height (Φ_{{bo}}) were found to be strong functions of temperature and voltage. In both regions, as the temperature increases, Φ_{{bo}} increases, whereas the value of n decreases. The high value of n at low temperatures is an evidence of deviation from thermionic emission, and it cannot be explained solely by tunneling mechanism, the existence of surface states and interfacial layer. Therefore, the Φ_{{bo}} versus q/kT plots were drawn for two linear regions of lnI-V plots, and these plots also revealed two distinct linear regions with different slopes between two temperature regions of 80-170 and 200-380 K which are called as low- and high-temperature range (LTR and HTR), respectively. Such behavior of these plots confirmed the existence of double Gaussian distribution (DGD) in the samples which in turn has mean barrier heights bar{Φ}_{{bo}} and standard deviations ( σ s). These values were obtained from the intercept and slope of these plots as 0.38 eV and 0.061 V for LTR and as 0.88 eV and 0.142 V for HTR (in RI), whereas they were obtained as 0.37 eV and 0.061 V for LTR and as 0.92 eV and 0.148 V for HTR (in RII), respectively. Thus, the modified ln( I s/ T 2)- q 2 σ s 2 /2 k 2 T 2 versus q/ kT plots were drawn, and the values of (bar{Φ}_{{bo}}) and effective Richardson constant ( A *) were extracted from the intercept and slope of these plots as 0.39 eV and 7.07 A/cm2 K2 for LTR and as 0.92 eV and 8.158 A/cm2 K2 for HTR (in RI), whereas they were extracted as 0.38 eV and 7.92 A/cm2 K2 for LTR and as 0.94 eV and 4.66 A/cm2 K2 for HTR

  16. Efficient detection of total cholesterol using (ChEt–ChOx/ZnO/Pt/Si) bioelectrode based on ZnO matrix

    Energy Technology Data Exchange (ETDEWEB)

    Batra, Neha; Sharma, Anjali [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Tomar, Monika [Department of Physics, Miranda House, University of Delhi, Delhi 110007 (India); Gupta, Vinay, E-mail: drguptavinay@gmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

    2014-07-01

    Present study highlights the importance of ZnO matrix prepared by vapour phase transport technique on platinum coated Si platform (ZnO/Pt/Si) as a potential matrix for the realization of highly sensitive and selective bioelectrode for detection of total cholesterol. Bienzymes cholesterol esterase (ChEt) and cholesterol oxidase (ChOx) have been immobilized onto the surface of ZnO thin film matrix by physical adsorption technique. The prepared bioelectrode (ChEt–ChOx/ZnO/Pt/Si) is utilized for detection of total cholesterol using the cyclic voltammetry technique. The bioelectrode (ChEt–ChOx/ZnO/Pt/Si) is found to exhibit efficient sensing response characteristics with high sensitivity of 190 μA mM{sup −1} cm{sup −2}; good linearity in the range of 0.5–12 mM total cholesterol concentration, and a very low Michaelis–Menten constant of 0.68 mM which indicates high affinity of bienzymes immobilized on ZnO towards the analyte (total cholesterol). The enhanced response is attributed to the development of ZnO thin film based matrix having good electron transport property and nanoporous morphology for effective loading of enzymes with favourable orientation. - Highlights: • Fabrication of a ZnO nanostructured thin film based efficient matrix • Utilizing prepared matrix for detection of total cholesterol (free + esterified) • Cholesterol oxidase and cholesterol esterase are the corresponding selective enzymes. • Vapour phase transport technique, for the fabrication of nanostructured ZnO matrix • The bioelectrode exhibits enhanced response characteristics towards total cholesterol detection.

  17. Influence of multi-hit capability on quantitative measurement of NiPtSi thin film with laser-assisted atom probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kinno, T., E-mail: teruyuki.kinno@toshiba.co.jp [Corporate Research and Development Center, Toshiba Corporation, 8 Shinsugita-cho, Isogo-ku, Yokohama 235-8522 (Japan); Akutsu, H.; Tomita, M. [Corporate Research and Development Center, Toshiba Corporation, 8 Shinsugita-cho, Isogo-ku, Yokohama 235-8522 (Japan); Kawanaka, S. [Center for Semiconductor Research and Development, Toshiba Corporation Semiconductor and Storage Products Company, 8 Shinsugita-cho, Isogo-ku, Yokohama 235-8522 (Japan); Sonehara, T. [Advanced Memory Development Center, Toshiba Corporation Semiconductor and Storage Products Company, 800 Yamano-Isshiki-cho, Yokkaichi, Mie 512-8550 (Japan); Hokazono, A. [Center for Semiconductor Research and Development, Toshiba Corporation Semiconductor and Storage Products Company, 8 Shinsugita-cho, Isogo-ku, Yokohama 235-8522 (Japan); Renaud, L.; Martin, I.; Benbalagh, R.; Salle, B. [Cameca SAS, 29 Quai des Gresillons, 92622 Gennevilliers Cedex (France); Takeno, S. [Corporate Research and Development Center, Toshiba Corporation, 8 Shinsugita-cho, Isogo-ku, Yokohama 235-8522 (Japan)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Laser-assisted atom probe tomography was applied to NiPtSi films on Si substrates. Black-Right-Pointing-Pointer Comparison of depth profiles of single-hit events and those of multi-hit events. Black-Right-Pointing-Pointer {approx}80% of Pt atoms were detected in multi-hit events. Black-Right-Pointing-Pointer Multiple-ion detection is important for Laser-assisted atom probe tomography. - Abstract: Laser-assisted atom probe tomography (LA-APT) was applied to NiPtSi (0, 30, and 50% Pt contents) thin films on Si substrates. Consistent results with those of high-resolution Rutherford backscattering spectrometry (HR-RBS) were obtained. Based on the obtained data sets, the composition profiles from only the signals of single-hit events, meaning detection of one ion by one laser pulse, were compiled. The profiles from only the signals of multi-hit events, meaning detection of multiple ions by one laser pulse, were also compiled. There were large discrepancies with respect to Ni and Pt concentrations among the compiled profiles and the original profiles including the signals of both types of detection events. Additionally, the profiles compiled from single-hit events showed that Si concentration in NiPtSi layer became smaller toward the surface, differing from the original profiles and the multi-hit profiles. These results suggest that capability of simultaneous multiple-ion detection is important for appropriate LA-APT analyses.

  18. GaAs Schottky versus p/i/n diodes for pixellated X-ray detectors

    CERN Document Server

    Bourgoin, J C

    2002-01-01

    We discuss the performances of GaAs p/i/n structures and Schottky barriers for application as photodetectors for high-energy photons. We compare the magnitude of the leakage current and the width of the depleted region for a given reverse bias. We mention the effect of states present at the metal-semiconductor interface on the extension of the space charge region in Schottky barriers. We illustrate this effect by a description of the capacitance behaviour of a Au-GaAs barrier under gamma irradiation.

  19. Electrical transport measurements and degradation of graphene/n-Si Schottky junction diodes

    Energy Technology Data Exchange (ETDEWEB)

    Park, No-Won; Lee, Won-Yong; Lee, Sang-Kwon; Koh, Jung-Hyuk [Chung-Ang University, Seoul (Korea, Republic of); Kim, Dong-Joo; Kim, Gil-Sung; Hyung, Jung-Hwan; Hong, Chang-Hee [Chonbuk National University, Jeonju (Korea, Republic of); Kim, Keun-Soo [Sejong University, Seoul (Korea, Republic of)

    2015-01-15

    We report on the electrical properties, such as the ideality factors and Schottky barrier heights, that were obtained by using current density - voltage (J - V ) and capacitance - voltage (C - V ) characteristics. To fabricate circularly- and locally-contacted Au/Gr/n-Si Schottky diode, we deposited graphene through the chemical vapor deposition (CVD) growth technique, and we employed reactive ion etching to reduce the leakage current of the Schottky diodes. The average values of the barrier heights and the ideality factors from the J .V characteristics were determined to be ∼0.79 ± 0.01 eV and ∼1.80 ± 0.01, respectively. The Schottky barrier height and the doping concentration from the C - V measurements were ∼0.85 eV and ∼1.76 x 10{sup 15} cm{sup -3}, respectively. From the J - V characteristics, we obtained a relatively low reverse leakage current of ∼2.56 x 10{sup -6} mA/cm{sup -2} at -2 V, which implies a well-defined rectifying behavior. Finally, we found that the Gr/n-Si Schottky diodes that were exposed to ambient conditions for 7 days exhibited a ∼3.2-fold higher sheet resistance compared with the as-fabricated Gr/n-Si diodes, implying a considerable electrical degradation of the Gr/n-Si Schottky diodes.

  20. Kinetic and computational study of dissociative substitution and phosphine exchange at tetrahedrally distorted cis-Pt(SiMePh2)2(PMe2Ph)2.

    Science.gov (United States)

    Wendt, O F; Deeth, R J; Elding, L I

    2000-11-13

    The substitution kinetics of Me2PhP in cis-Pt(SiMePh2)2(PMe2Ph)2 (1) by the chelating ligand bis(diphenylphosphino)ethane has been followed at 25.0 degrees C in dichloromethane by stopped-flow spectrophotometry. Addition of the leaving ligand causes mass-law retardation compatible with a dissociative process via a three-coordinate transition state or intermediate. Exchange of Me2PhP in 1 has been studied by variable-temperature magnetization transfer 1H NMR in toluene-d8, giving kex326 = 1.76 +/- 0.12 s-1, delta H++ = 117.8 +/- 2.1 kJ mol-1, and delta S++ = 120 +/- 7 J K-1 mol-1. An exchange rate constant independent of the concentrations of free phosphine, a strongly positive delta S++, and nearly equal exchange and ligand dissociation rate constants also support a dissociative process. Density functional theory (DFT) calculations for a dissociative process give an estimate for the Pt-P bond energy of 98 kJ mol-1 for R = R' = Me, which is in reasonable agreement with the experimental activation energy given the differences between the substituents used in the calculation and those employed experimentally. DFT calculations on cis-Pt(PR3)2(SiR'3)2 (R = H, CH3; R' = H, CH3) are consistent with the experimental molecular structure and show that methyl substituents on the Si donors are sufficient to induce the observed tetrahedral twist. The optimized Si-Pt-Si angle in cis-Pt(SiH3)2(PH3)2 is not significantly altered by changing the P-Pt-P angle from its equilibrium value of 104 degrees to 80 degrees or 120 degrees. The origin of the tetrahedral twist is therefore not steric but electronic. The Si-Pt-Si angle is consistently less than 90 degrees, but the Si-Si distance is still too long to support an incipient reductive elimination reaction with its attendant Si-Si bonding interaction. Instead, it appears that four tertiary ligands introduce a steric strain which can be decreased by a twist of two of the ligands out of the plane; this twist is only possible when two

  1. Polymer/metal hybrid multilayers modified Schottky devices

    Energy Technology Data Exchange (ETDEWEB)

    Torrisi, V.; Isgrò, G.; Li Destri, G.; Marletta, G. [Laboratory for Molecular Surfaces and Nanotechnology (LAMSUN), Department of Chemical Sciences, University of Catania and CSGI, Viale A. Doria 6, 95125 Catania (Italy); Ruffino, F.; Grimaldi, M. G. [Dipartimento di Fisica ed Astronomia-Università di Catania, via S. Sofia 64, 95123 Catania (Italy); MATIS IMM-CNR, via S. Sofia 64, 95123 Catania (Italy); Crupi, I. [MATIS IMM-CNR, via S. Sofia 64, 95123 Catania (Italy)

    2013-11-04

    Insulating, polymethylmethacrylate (PMMA), and semiconducting, poly(3-hexylthiophene) (P3HT), nanometer thick polymers/Au nanoparticles based hybrid multilayers (HyMLs) were fabricated on p-Si single-crystal substrate. An iterative method, which involves, respectively, spin-coating (PMMA and P3HT deposition) and sputtering (Au nanoparticles deposition) techniques to prepare Au/HyMLs/p-Si Schottky device, was used. The barrier height and the ideality factor of the Au/HyMLs/p-Si Schottky devices were investigated by current-voltage measurements in the thickness range of 1–5 bilayers. It was observed that the barrier height of such hybrid layered systems can be tuned as a function of bilayers number and its evolution was quantified and analyzed.

  2. Longitudinal peak detected Schottky spectrum

    CERN Document Server

    Shaposhnikova, E

    2009-01-01

    The "peak detected Schottky" spectrum is a diagnostic used since the late seventies for beam observation in the SPS and now already applied to the LHC. This tool was always believed, however without proof, to give a good picture of the particle distribution in synchrotron frequencies similar to the longitudinal Schottky spectrum of unbunched beam for revolution frequencies.In this paper an analysis of this measurement technique is presented both in a general form and for the particular realisation in the SPS. In addition the limitations of the present experimental set-up are discussed together with possible improvements. The analysis shows that for an optimised experimental set-up the spectrum of the peak detected signal is very close to the synchrotron frequency distribution inside the bunch - much closer than that given by the traditional longitudinal bunched-beam Schottky spectrum.

  3. Highly sensitive enzyme-free immunosorbent assay for porcine circovirus type 2 antibody using Au-Pt/SiO2 nanocomposites as labels.

    Science.gov (United States)

    Wu, Long; Yin, Wenmin; Tang, Kun; Shao, Kang; Li, Qin; Wang, Pan; Zuo, Yunpeng; Lei, Xiaomin; Lu, Zhicheng; Han, Heyou

    2016-08-15

    Improving the performance of conventional enzyme-linked immunosorbent assay (ELISA) is of great importance to meet the demand of early clinical diagnosis of various diseases. Herein, we report a feasible enzyme-free immunosorbent assay (EFISA) system using antibody conjugated Au-Pt/SiO2 nanocomposites (APS NCs) as labels. In this system, Au-Pt/SiO2 nanospheres (APS NPs) were first synthesized by wet chemical method and exhibited intrinsic peroxidase and catalase-like activity with excellent water-solubility. Then APS NCs were utilized as labels to replace HRP conjugated antibody, and Fe3O4 magnetic beads (MBs) to entrap the analyte. To discuss the performance of EFISA system, Human IgG was served as a model analyte, and porcine circovirus type 2 (PCV2) serums as real samples. The system boosted the detection limit of HIgG to 75pgmL(-1) with a RSD below 5%, a 264-fold improvement as compared with conventional ELISA. This is the first time that APS NCs have been used and successfully optimized for the sensitive dilution detection of PCV2 antibody (5:10(7)) in ELISA. Besides, APS NCs have advantages related to low cost, easy preparation, good stability and tunable catalytic activity, which make them a potent enzyme mimetic candidate and may find potential applications in bioassays and clinical diagnostics.

  4. Carrier transport in reverse-biased graphene/semiconductor Schottky junctions

    Science.gov (United States)

    Tomer, D.; Rajput, S.; Hudy, L. J.; Li, C. H.; Li, L.

    2015-04-01

    Reverse-biased graphene (Gr)/semiconductor Schottky diodes exhibit much enhanced sensitivity for gas sensing. However, carrier transport across these junctions is not fully understood yet. Here, Gr/SiC, Gr/GaAs, and Gr/Si Schottky junctions under reverse bias are investigated by temperature-dependent current-voltage measurements. A reduction in barrier height with increasing bias is observed for all junctions, suggesting electric-field enhanced thermionic emission. Further analysis of the field dependence of the reverse current reveals that while carrier transport in Gr/SiC Schottky junctions follows the Poole-Frenkel mechanism, it deviates from both the Poole-Frankel and Schottky mechanisms in Gr/Si and Gr/GaAs junctions, particularly for low temperatures and fields.

  5. Structural and electronic properties and the fermi surface of the new non-centrosymmetric superconductors: 3.6 K CaIrSi3 and 2.3 K CaPtSi3

    Science.gov (United States)

    Bannikov, V. V.; Shein, I. R.; Ivanovskii, A. L.

    2010-09-01

    Ab initio FLAPW-GGA calculations have been performed to investigate structural properties, electronic band structure, and Fermi surface topology of the newly discovered non-centrosymmetric superconductors: 3.6 K CaIrSi3 and 2.3 K CaPtSi3. As a result, the peculiarities of the crystal structure, electronic bands, total and site-projected l-decomposed densities of states, and the shape of the Fermi surface for CaIrSi3 and CaPtSi3 were obtained and analyzed.

  6. Enhancement in performance of polycarbazole-graphene nanocomposite Schottky diode

    Directory of Open Access Journals (Sweden)

    Rajiv K. Pandey

    2013-12-01

    Full Text Available We report formation of polycarbazole (PCz–graphene nanocomposite over indium tin oxide (ITO coated glass substrate using electrochemical technique for fabrication of high performance Schottky diodes. The synthesized nanocomposite is characterized before fabrication of devices for confirmation of uniform distribution of graphene nanosheets in the polymer matrix. Pure PCz and PCz-graphene nanocomposites based Schottky diodes are fabricated of configuration Al/PCz/ITO and Al/PCz-graphene nanocomposite/ITO, respectively. The current density–voltage (J-V characteristics and diode performance parameters (such as the ideality factor, barrier height, and reverse saturation current density are compared under ambient condition. Al/PCz-graphene nanocomposite/ITO device exhibits better ideality factor in comparison to the device formed using pure PCz. It is also observed that the Al/PCz-graphene nanocomposite/ITO device shows large forward current density and low turn on voltage in comparison to Al/PCz/ITO device.

  7. Electrical parameters and current conduction mechanism in Cr/Au/n-InP Schottky structure at different annealing temperatures

    Science.gov (United States)

    Reddy, M. Bhaskar; Padma, R.; Reddy, V. Rajagopal

    2015-06-01

    Cr/Au/n-InP Schottky structures are fabricated and their electrical characteristics are investigated at different annealing temperatures. As-deposited Cr/Au/n-InP Schottky diode exhibits a barrier height of 0.51 eV (I-V) and 0.64 eV (C-V), which increases to 0.63 eV (I-V) and 0.75 eV (C-V) after annealing at 100 °C. A maximum barrier height of 0.71 eV (I-V) and 0.81 eV (C-V) is achieved for the Cr/Au Schottky contacts after annealing at 200 °C. Further, it is observed that the Schottky barrier height slightly decreases upon annealing at temperature of 300 °C and the obtained values are 0.58 eV (I-V), 0.69 eV (C-V). The reverse-bias leakage current mechanism of Cr/Au/n-InP Schottky barrier diode is investigated. Investigations reveal that the Schottky emission is the dominant mechanism and the Poole-Frenkel emission occurs only in the high voltage region.

  8. Structural analysis of SiC Schottky diodes failure mechanism under current overload

    Science.gov (United States)

    León, J.; Berthou, M.; Perpiñà, X.; Banu, V.; Montserrat, J.; Vellvehi, M.; Godignon, P.; Jordà, X.

    2014-02-01

    1.2 kV-10 A tungsten Schottky diodes (W-SBD) have been aged and tested at limit under current overload (surge current pulses) to determine their structural weakest spots. All devices showed no ageing at 40 A amplitudes and a surge current capability higher than 60 A. Infrared lock-in measurements have located the weakest spots on the surface of failed chips and allowed us to non-invasively infer their origin: Schottky barrier modification by metal contact change. After, a focused ion beam coupled with scanning electron microscope has been used to analyse the physical signature at these locations. These inspections have revealed that the destruction mechanism responsible for their failure was the electromigration and thermomigration of tungsten into aluminum, locally modifying the electrical behaviour of the Schottky barrier (loss of blocking capability).

  9. Current Transport in Copper Schottky Contacts to a-Plane/c-Plane n-Type MoSe2

    Institute of Scientific and Technical Information of China (English)

    C. K. Sumesh; K. D. Patel; V. M. Pathak; R. Srivastav

    2011-01-01

    @@ We identically prepared Cu-nMoSe2(a-plane) and Cu-nMoSe2(c-plane) Schottky barrier diodes(SBDs) on the same n-type MoSe2 single crystal.The effective Schottky barrier heights(SBHs) and ideality factors were obtained from the current-voltage-temperature(I-V-T) characteristics.The barrier height and ideality factor,estimated from the conventional thermionic emission model by assuming a Gaussian barrier distribution, are highly dependent on temperature.A notable deviation from the theoretical Richardson constant value is also observed in the conventional Richardson plot.The decrease in the experimental barrier height φBO and an increase in the ideality factor n with a decrease in temperature have been explained on the basis of barrier height inhomogeneities at the metal-semiconductor interface.It is proven that the presence of a distribution of barrier heights is responsible for the apparent decrease of the zero bias barrier height.The voltage dependence of the standard deviation causes the increase of the ideality factor at low temperatures.The value of the Richardson constant obtained without considering the inhomogeneous barrier heights is much closer than the theoretical value.The Cu-nMoSe2(a-plane) Schottky diode shows better results in comparison with the nMoSe2(c-plane)Schottky diode.

  10. Schottky signal analysis: tune and chromaticity computation

    CERN Document Server

    Chanon, Ondine

    2016-01-01

    Schottky monitors are used to determine important beam parameters in a non-destructive way. The Schottky signal is due to the internal statistical fluctuations of the particles inside the beam. In this report, after explaining the different components of a Schottky signal, an algorithm to compute the betatron tune is presented, followed by some ideas to compute machine chromaticity. The tests have been performed with offline and/or online LHC data.

  11. ALD TiO2 thin film as dielectric for Al/p-Si Schottky diode

    Indian Academy of Sciences (India)

    Sefa B K Aydin; Dilber E Yildiz; Hatice Kanbur Çavuş; Recep Şahingöz

    2014-12-01

    Electrical analysis of Al/p-Si Schottky diode with titanium dioxide (TiO2) thin film was performed at room temperature. The forward and reverse bias current–voltage (–) characteristics of diode were studied. Using thermionic emission (TE) theory, the main electrical parameters of the Al/TiO2/p-Si Schottky diode such as ideality factor (), zero bias barrier height (Bo) and series resistance (s) were estimated from forward bias – plots. At the same time, values of , Bo and s were obtained from Cheung’s method. It was shown that electrical parameters obtained from TE theory and Cheung’s method exhibit close agreement with each other. The reverse-bias leakage current mechanism of Al/TiO2/p-Si Schottky barrier diodes was investigated. The – curves in the reverse direction are taken and interpreted via both Schottky and Poole–Frenkel effects. Schottky effect was found to be dominant in the reverse direction. In addition, the capacitance–voltage (–) and conductance–voltage (/–) characteristics of diode were investigated at different frequencies (50–500 kHz). The frequency dependence of interface states density was obtained from the Hill–Coleman method and the voltage dependence of interface states density was obtained from the high–low frequency capacitance method.

  12. Silicide Schottky Contacts to Silicon: Screened Pinning at Defect Levels

    Energy Technology Data Exchange (ETDEWEB)

    Drummond, T.J.

    1999-03-11

    Silicide Schottky contacts can be as large as 0.955 eV (E{sub v} + 0.165 eV) on n-type silicon and as large as 1.05 eV (E{sub c} {minus} 0.07 eV) on p-type silicon. Current models of Schottky barrier formation do not provide a satisfactory explanation of occurrence of this wide variation. A model for understanding Schottky contacts via screened pinning at defect levels is presented. In the present paper it is shown that most transition metal silicides are pinned approximately 0.48 eV above the valence band by interstitial Si clusters. Rare earth disilicides pin close to the divacancy acceptor level 0.41 eV below the conduction band edge while high work function silicides of Ir and Pt pin close to the divacancy donor level 0.21 eV above the valence band edge. Selection of a particular defect pinning level depends strongly on the relative positions of the silicide work function and the defect energy level on an absolute energy scale.

  13. Schottky contact formation on polar and non-polar AlN

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, Pramod; Bryan, Isaac; Bryan, Zachary; Tweedie, James; Kirste, Ronny; Collazo, Ramon; Sitar, Zlatko [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7919 (United States)

    2014-11-21

    The interfaces of m- and c-plane AlN with metals of different work functions and electro-negativities were characterized and the Schottky barrier heights were measured. The Schottky barrier height was determined by measuring the valence band maximum (VBM) with respect to the Fermi level at the surface (interface) before (after) metallization. VBM determination included accurate modeling and curve fitting of density of states at the valence band edge with the XPS data. The experimental behavior of the barrier heights could not be explained by the Schottky-Mott model and was modeled using InterFace-Induced Gap States (IFIGS). A slope parameter (S{sub X}) was used to incorporate the density of surface states and is a measure of Fermi level pinning. The experimental barriers followed theoretical predictions with a barrier height at the surface Fermi level (Charge neutrality level (CNL)) of ∼2.1 eV (∼2.7 eV) on m-plane (c-plane) and S{sub X} ∼ 0.36 eV/Miedema unit. Slope parameter much lower than 0.86 implied a surface/interface states dominated behavior with significant Fermi level pinning and the measured barrier heights were close to the CNL. Titanium and zirconium provided the lowest barriers (1.6 eV) with gold providing the highest (2.3 eV) among the metals analyzed on m-plane. It was consistently found that barrier heights decreased from metal polar to non-polar surfaces, in general, due to an increasing CNL. The data indicated that charged IFIGS compensate spontaneous polarization charge. These barrier height and slope parameter measurements provided essential information for designing Schottky diodes and other contact-based devices on AlN.

  14. Radiation hardness of n-GaN schottky diodes

    Energy Technology Data Exchange (ETDEWEB)

    Lebedev, A. A., E-mail: shura.lebe@mail.ioffe.ru; Belov, S. V.; Mynbaeva, M. G.; Strel’chuk, A. M.; Bogdanova, E. V. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Makarov, Yu. N. [Nitride Crystals Group (Russian Federation); Usikov, A. S. [Nitride Crystals Inc. (United States); Kurin, S. Yu.; Barash, I. S.; Roenkov, A. D. [Nitride Crystals Group (Russian Federation); Kozlovski, V. V. [St. Petersburg State Polytechnic University (Russian Federation)

    2015-10-15

    Schottky-barrier diodes with a diameter of ∼10 µm are fabricated on n-GaN epitaxial films grown by hydride vapor-phase epitaxy (HVPE) on sapphire substrates. The changes in the parameters of the diodes under irradiation with 15 MeV protons are studied. The carrier removal rate was found to be 130–145 cm{sup –1}. The linear nature of the dependence N = f(D) (N is the carrier concentration, and D, the irradiation dose) shows that compensation of the material is associated with transitions of electrons from shallow donors to deep acceptor levels which are related to primary radiation defects.

  15. 1/f noise in forward biased high voltage 4H-SiC Schottky diodes

    Science.gov (United States)

    Shabunina, Eugenia I.; Levinshtein, Michael E.; Shmidt, Natalia M.; Ivanov, Pavel A.; Palmour, John W.

    2014-06-01

    The 1/f noise has been investigated for the first time at 300 and 77 K in high-quality 4H-SiC Schottky diodes. It is shown that, at 77 K, the dependence of the spectral noise density on current, SI(I), differs fundamentally between the cases of the current flowing through the main part of the diode with a comparatively high barrier and the current flowing through the nano-sized patches with a comparatively low barrier.

  16. Effect of CO on Characteristics of AlGaN/GaN Schottky Diode

    Institute of Scientific and Technical Information of China (English)

    FENG Chun; WANG Zhan-Guo; WANG Xiao-Liang; YANG Cui-Bai; XIAO Hong-Ling; ZHANG Ming-Lan; JIANG Li-Juan; TANG Jian; HU Guo-Xin; WANG Jun-Xi

    2008-01-01

    @@ Pt Schottky diode gas sensors for CO are fabricated using AlGaN/GaN high electron mobility transistor (HEMTs) structure. The diodes show a remarkable sensor signal (3 mA, in N2; 2mA in air ambient) biased 2 V after 1% CO is introduced at 50℃. The Schottky barrier heights decrease for 36 meV and 27 meV in the two cases respectively. The devices exhibit a slow recovery characteristic in air ambient but almost none in the background of pure N2, which reveals that oxygen molecules could accelerate the desorption of CO and offer restrictions to CO detection.

  17. Parameter extraction for a Ti/4H-SiC Schottky diode

    Institute of Scientific and Technical Information of China (English)

    王守国; 张义门; 张玉明

    2003-01-01

    Based on the MIS model, a simple method to extract parameters of SiC Schottky diodes is presented using the I-V characteristics. The interface oxide capacitance Ci is extracted for the first time, as far as we know. Parameters of 4H-SiC Schottky diodes fabricated for testing in this paper are: the ideality factor n, the series resistance Rs, the zero-field barrier height φB0, the interface state density Dit, the interface oxide capacitance Ci and the neutral level of interface states φ0.

  18. 1700 V SiC Schottky diodes scaled to 25 A

    Energy Technology Data Exchange (ETDEWEB)

    Peters, D.; Dohnke, K.O.; Hecht, C.; Stephani, D. [SiCED Electronics Development Ltd., Erlangen (Germany)

    2001-07-01

    This paper reports on a study of SiC Schottky diodes focused on high current rating and high blocking voltage: 25 A / 1200 V and 1700V, resp. With an active area of 10 mm{sup 2} we successfully explored new ground for SiC devices. The device concept, fabrication process, yield aspects and measured results of static and dynamic characteristics as well as the temperature behavior are described. The reverse currents are very low (<500 {mu}A) even at 125 C and their temperature dependence is lower than expected by thermionic emission since tunneling mechanisms through the Schottky barrier rule the current transport at high blocking voltages. (orig.)

  19. Fabrication of novel electrolyte-layer free fuel cell with semi-ionic conductor (Ba0.5Sr0.5Co0.8Fe0.2O3-δ- Sm0.2Ce0.8O1.9) and Schottky barrier

    Science.gov (United States)

    Afzal, Muhammad; Saleemi, Mohsin; Wang, Baoyuan; Xia, Chen; Zhang, Wei; He, Yunjuan; Jayasuriya, Jeevan; Zhu, Bin

    2016-10-01

    Perovskite Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) is synthesized via a chemical co-precipitation technique for a low temperature solid oxide fuel cell (LTSOFC) (300-600 °C) and electrolyte-layer free fuel cell (EFFC) in a comprehensive study. The EFFC with a homogeneous mixture of samarium doped ceria (SDC): BSCF (60%:40% by weight) which is rather similar to the cathode (SDC: BSCF in 50%:50% by weight) used for a three layer SOFC demonstrates peak power densities up to 655 mW/cm2, while a three layer (anode/electrolyte/cathode) SOFC has reached only 425 mW/cm2 at 550 °C. Chemical phase, crystal structure and morphology of the as-prepared sample are characterized by X-ray diffraction and field emission scanning electron microscopy coupled with energy dispersive spectroscopy. The electrochemical performances of 3-layer SOFC and EFFC are studied by electrochemical impedance spectroscopy (EIS). As-prepared BSCF has exhibited a maximum conductivity above 300 S/cm at 550 °C. High performance of the EFFC device corresponds to a balanced combination between ionic and electronic (holes) conduction characteristic. The Schottky barrier prevents the EFFC from the electronic short circuiting problem which also enhances power output. The results provide a new way to produce highly effective cathode materials for LTSOFC and semiconductor designs for EFFC functions using a semiconducting-ionic material.

  20. Influence of No on the Reduction of NO2 with CO over Pt/SiO2 in the Presence of O2

    Institute of Scientific and Technical Information of China (English)

    LI,Ming-Shi; SESHAN,K.; LEFFERTS,Leon

    2007-01-01

    Reduction of NO2 with CO in the presence of NO and excess oxygen,a model mixture for flue gas,over a 0.1%Pt/SiO2 catalyst was studied.The related reaction mechanisms,such as oxidation of CO and NO,were discussed.It was found that there was a narrow temperature window(180-190℃)for the reduction of NO2 by CO.When the temperature was lower than the lower limit of the window,the reduction hardly occurred,while when the temperature was higher than the upper limit of the window,the direct oxidation of CO by O2 occurred and thereby NO2 could not be effectively reduced by CO.The presence of NO shifted the window to higher temperatures owing to the inhibition effect of NO on the activation of O2 on Pt,which made it possible to reduce NO2 by CO in flue gas.

  1. Electrical characteristics of Pt-ZnO Schottky nano-contact

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The electrical characteristics of Pt-ZnO Schottky nano-contact have been studied. Well aligned ZnO nanorod arrays were synthesized by two-step wet-chemical method. A Pt-coated conducting probe of atomic force microscope was placed on the head face of the ZnO nanorod, thereby forming a Pt-ZnO nano-contact. The I-V characteristic curve shows that the Pt-ZnO nano-contact exhibits rectifying effect, like a Schottky diode with an ideality factor of 3.2 and a reverse-bias breakdown voltage more than -10 V. The study suggests that a high electric field is induced on the ZnO beneath the contact point when a bias voltage is applied, hence, the Schottky barrier thickness is decreased, and results in easier tunneling across the Pt-ZnO interface and a large ideality factor.

  2. Improved Schottky contacts to InGaN alloys by a photoelectrochemical treatment

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Yin; Cai, Qing; Chen, Dunjun; Lu, Hai; Zhang, Rong; Zheng, Youdou [Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 (China); Yang, Lianhong [Department of Physics, Changji College, Changji, 831100 (China); Xue, Junjun [School of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing, 210093 (China)

    2016-04-15

    We report on improved electrical properties of Schottky contacts to InGaN alloys by introducing a photoelectrochemical treatment. The Schottky barrier height determined by a thermionic-field emission model, a dominating forward-current-transport mechanism, increased by 0.15 eV from 1.02 eV for conventional contacts to 1.17 eV for those with photoelectrochemical treatment at room temperature, while the ideality factors is closer to 1 after photoelectrochemical treatment. Furthermore, the reverse leakage mechanism varies from an ohmic transport mechanism at relatively low voltage and space charge-limited current mechanism at relatively high voltage for conventional contacts to Frenkel-Poole emission for improved Schottky contacts, which is attributed to partly removing surface states by the photoelectrochemical treatment. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Fabrication and characterization of graphene/AlGaN/GaN ultraviolet Schottky photodetector

    Science.gov (United States)

    Kumar, M.; Jeong, H.; Polat, K.; Okyay, A. K.; Lee, D.

    2016-07-01

    We report on the fabrication and characterization of a Schottky ultraviolet graphene/AlGaN/GaN photodetector (PD). The fabricated device clearly exhibits rectification behaviour, indicating that the Schottky barrier is formed between the AlGaN and the mechanically transferred graphene. The Schottky parameters are evaluated using an equivalent circuit with two diodes connected back-to-back in series. The PD shows a low dark current of 4.77  ×  10-12 A at a bias voltage of  -2.5 V. The room temperature current-voltage (I-V) measurements of the graphene/AlGaN/GaN Schottky PD exhibit a large photo-to-dark contrast ratio of more than four orders of magnitude. Furthermore, the device shows peak responsivity at a wavelength of 350 nm, corresponding to GaN band edge and a small hump at 300 nm associated to the AlGaN band edge. In addition, we examine the behaviour of Schottky PDs with responsivities of 0.56 and 0.079 A W-1 at 300 and 350 nm, respectively, at room temperature.

  4. Schottky Noise and Beam Transfer Functions

    Energy Technology Data Exchange (ETDEWEB)

    Blaskiewicz M.; Blaskiewicz M.

    2016-12-01

    Beam transfer functions (BTF)s encapsulate the stability properties of charged particle beams. In general one excites the beam with a sinusoidal signal and measures the amplitude and phase of the beam response. Most systems are very nearly linear and one can use various Fourier techniques to reduce the number of measurements and/or simulations needed to fully characterize the response. Schottky noise is associated with the finite number of particles in the beam. This signal is always present. Since the Schottky current drives wakefields, the measured Schottky signal is influenced by parasitic impedances.

  5. Modification of electrical properties of Au/n-type InP Schottky diode with a high-k Ba0.6Sr0.4TiO3 interlayer

    Science.gov (United States)

    Thapaswini, P. Prabhu; Padma, R.; Balaram, N.; Bindu, B.; Rajagopal Reddy, V.

    2016-05-01

    Au/Ba0.6Sr0.4TiO3 (BST)/n-InP metal/insulator/semiconductor (MIS) Schottky diodes have been analyzed by current-voltage (I-V) and capacitance-voltage (C-V) measurements. The surface morphology of the BST films on InP is fairly smooth. The Au/BST/n-InP MIS Schottky diode shows better rectification ratio and low leakage current compared to the conventional Au/n-InP metal-semiconductor (MS) Schottky diode. Higher barrier height is achieved for the MIS Schottky diode compared to the MS Schottky diode. The Norde and Cheung's methods are employed to determine the barrier height, ideality factor and series resistance. The interface state density (NSS) is determined from the forward bias I-V data for both the MS and MIS Schottky diodes. Results reveal that the NSS of the MIS Schottky diode is lower than that of the MS Schottky diode. The Poole-Frenkel emission is found dominating the reverse current in both Au/n-InP MS and Au/BST/n-InP MIS Schottky diodes, indicating the presence of structural defects and trap levels in the dielectric film.

  6. Instrumentation And Diagnostics Using Schottky Signals

    CERN Document Server

    Nolden, F

    2001-01-01

    Schottky signal measurements are a widely used tool for the determination of longitudinal and transverse dynamical properties of hadron beams in circular accelerators and storage rings. When applied to coasting beams, it is possible to deduce properties as the momentum distribution. the Qx,y-values and the average betatron amplitudes. Scientific applications have been developed in the past few years, as well, namely nuclear Schottky mass spectrometry and lifetime measurements. Schottky signals from a coasting beam are random signals which appear at every revolution harmonic and the respective betatron sidebands. Their interpretation is more or less straightforward unless the signal is perturbed by collective effects in the case of high phase space density. Schottky signals from bunched beams reveal the synchrotron oscillation frequency, from which the effective rf voltage seen by the beam can be deduced. The detection devices can be broad-band or narrowband. The frequency range is usually in the range between...

  7. Graphene-GaN Schottky Photodiodes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Integration of graphene as the top metal on GaN Schottky. This will replace platinum, which is 50% transparent at the desired wavelength, with graphene, which has...

  8. Fabrication and characterization of flexible Ag/ZnO Schottky diodes on polyimide substrates

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, XinAn; Zhai, JunXia; Yu, XianKun; Ding, LingHong; Zhang, WeiFeng, E-mail: wfzhang@henu.edu.cn

    2013-12-02

    In this paper, we report on the fabrication of flexible Ag/ZnO Schottky diodes on polyimide substrates by pulsed laser deposition. The structural and optical properties of the ZnO films were investigated by X-ray diffractometry and spectrophotometry. The current–voltage (I–V) characteristics of flexible Schottky diodes with and without bending were measured at room temperature. The results show that the devices have good rectifying behaviors with an ideality factor of 2.8 and a Schottky barrier height of 0.54 eV according to the I–V characteristics. It was seen that the forward bias current–voltage characteristics at sufficiently large voltages have shown the effect of series resistance. The values of the ideality factor, series resistance and barrier height obtained from Cheung and Norde methods were compared, and it was seen that there was an agreement with each other. The results show that the electrical properties of flexible diodes change little when measured with or without bending condition, indicating that the devices have potential applications in flexible electronics. - Highlights: • Flexible Ag/ZnO Schottky diodes were fabricated. • The electrical parameters of the diodes were obtained and analyzed. • The electrical properties of the diodes with bending were also discussed.

  9. Schottky nanocontact of one-dimensional semiconductor nanostructures probed by using conductive atomic force microscopy

    Science.gov (United States)

    Lee, Jung Ah; Rok Lim, Young; Jung, Chan Su; Choi, Jun Hee; Im, Hyung Soon; Park, Kidong; Park, Jeunghee; Kim, Gyu Tae

    2016-10-01

    To develop the advanced electronic devices, the surface/interface of each component must be carefully considered. Here, we investigate the electrical properties of metal-semiconductor nanoscale junction using conductive atomic force microscopy (C-AFM). Single-crystalline CdS, CdSe, and ZnO one-dimensional nanostructures are synthesized via chemical vapor transport, and individual nanobelts (or nanowires) are used to fabricate nanojunction electrodes. The current-voltage (I -V) curves are obtained by placing a C-AFM metal (PtIr) tip as a movable contact on the nanobelt (or nanowire), and often exhibit a resistive switching behavior that is rationalized by the Schottky (high resistance state) and ohmic (low resistance state) contacts between the metal and semiconductor. We obtain the Schottky barrier height and the ideality factor through fitting analysis of the I-V curves. The present nanojunction devices exhibit a lower Schottky barrier height and a higher ideality factor than those of the bulk materials, which is consistent with the findings of previous works on nanostructures. It is shown that C-AFM is a powerful tool for characterization of the Schottky contact of conducting channels between semiconductor nanostructures and metal electrodes.

  10. Influence of surface cleaning effects on properties of Schottky diodes on 4H-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Kwietniewski, N. [Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, ul. Koszykowa 75, 00-662 Warsaw (Poland)], E-mail: nkwietni@ite.waw.pl; Sochacki, M.; Szmidt, J. [Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, ul. Koszykowa 75, 00-662 Warsaw (Poland); Guziewicz, M.; Kaminska, E.; Piotrowska, A. [Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw (Poland)

    2008-10-15

    Ir/4H-SiC and IrO{sub 2}/4H-SiC Schottky diodes are reported in terms of different methods of surface pretreatment before contact deposition. In order to find the effect of surface preparation processes on Schottky characteristics the SiC wafers were respectively cleaned using the following processes: (1) RCA method followed by buffered HF dip. Next, the surface was oxidized (5.5 nm oxide) using a rapid thermal processing reactor chamber and circular geometry windows were opened in the oxide layer before metallization deposition; (2) the same as sequence (1) but with an additional in situ sputter etching step before metallization deposition; (3) cleaning in organic solvents followed by buffered HF dip. The I-V characteristics of Schottky diodes were analyzed to find a correlation between extracted parameters and surface treatment. The best results were obtained for the sequence (1) taking into account theoretical value of Schottky barrier height. The contacts showed excellent Schottky behavior with ideality factors below 1.08 and barrier heights of 1.46 eV and 1.64 eV for Ir and IrO{sub 2}, respectively. Very promising results were obtained for samples prepared using the sequence (2) taking into account the total static power losses because the modified surface preparation results in a decrease in the forward voltage drop and reverse leakage current simultaneously. The contacts with ideality factor below 1.09 and barrier height of 1.02 eV were fabricated for Ir/4H-SiC diodes in sequence (2)

  11. Theoretical Analysis of Current Crowding Effect in Metal/AlGaN/GaN Schottky Diodes and Its Reduction by Using Polysilicon in Anode

    Institute of Scientific and Technical Information of China (English)

    CHEN Jia-Rong; HAN Qi-Feng; DUAN Cheng-Hong; ZHOU Xiu-Ju; CHEN Wen-Jin; WANG Yu-Qi; QIU Kai; LI Xin-Hua; ZHONG Fei; YIN Zhi-Jun; JI Chang-Jian; CAO Xian-Cun

    2007-01-01

    There exists a current crowding effect in the anode of A1GaN/GaN heteto junction Schottky diodes, causing local overheating when working at high power density, and undermining their performance. The seriousness of this effect is illustrated by theoretical analysis. A method of reducing this effect is proposed by depositing a polysilicon layer on the Schottky barrier metal. The effectiveness of this method is provided through computer simulation.Power consumption of the polysilicon layer is also calculated and compared to that of the Schottky junction to ensure the applicability of this method.

  12. Current-voltage characteristics and charge DLTS spectra of proton-bombarded Schottky diodes on semi-insulating GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Thurzo, I. (Inst. of Physics, Slovak Academy of Sciences, Bratislava (Slovakia)); Hrubcin, L. (Inst. of Electrical Engineering, Slovak Academy of Sciences, Bratislava (Slovakia)); Bartos, J. (Inst. of Physics, Slovak Academy of Sciences, Bratislava (Slovakia)); Pincik, E. (Inst. of Physics, Slovak Academy of Sciences, Bratislava (Slovakia))

    1993-10-01

    Changes in the current-voltage characteristics and charge DLTS spectra of Schottky diodes on semi-insulating GaAs after irradiation by protons at different energies and doses are presented and discussed. Apart from a progressive degradation of the Schottky barriers with enhanced proton energy and dose, there is a threshold, positioned between 10[sup 14] and 10[sup 15] protons/cm[sup 2], for observing trap-limited transients. (orig.)

  13. Modified electrical characteristics of Pt/n-type Ge Schottky diode with a pyronine-B interlayer

    Science.gov (United States)

    Jyothi, I.; Janardhanam, V.; Rajagopal Reddy, V.; Choi, Chel-Jong

    2014-11-01

    The electrical characteristics of a Pt/n-type Ge Schottky diode with a pyronine-B (PYR-B) interlayer prepared by spin coating was investigated by current-voltage (I-V) and capacitance-voltage (C-V) measurements. It was observed that the barrier height of Pt/PYR-B/n-type Ge (0.65 eV) was higher than that of the conventional Pt/n-type Ge Schottky diode (0.58 eV). This is attributed to the fact that the organic interlayer increases the effective barrier height by influencing the space-charge region of Ge. The introduction of the PYR-B interlayer led to a reduction of the interface state density in the Pt Schottky contact to n-type Ge. The electric field dependence of the reverse leakage current revealed that Schottky emission and Poole-Frenkel emission mechanisms dominated the reverse current in the Pt/n-type Ge and Pt/PYR-B/n-type Ge Schottky diodes, respectively.

  14. Characterization technique for inhomogeneous 4H-SiC Schottky contacts: A practical model for high temperature behavior

    Science.gov (United States)

    Brezeanu, G.; Pristavu, G.; Draghici, F.; Badila, M.; Pascu, R.

    2017-08-01

    In this paper, a characterization technique for 4H-SiC Schottky diodes with varying levels of metal-semiconductor contact inhomogeneity is proposed. A macro-model, suitable for high-temperature evaluation of SiC Schottky contacts, with discrete barrier height non-uniformity, is introduced in order to determine the temperature interval and bias domain where electrical behavior of the devices can be described by the thermionic emission theory (has a quasi-ideal performance). A minimal set of parameters, the effective barrier height and peff, the non-uniformity factor, is associated. Model-extracted parameters are discussed in comparison with literature-reported results based on existing inhomogeneity approaches, in terms of complexity and physical relevance. Special consideration was given to models based on a Gaussian distribution of barrier heights on the contact surface. The proposed methodology is validated by electrical characterization of nickel silicide Schottky contacts on silicon carbide (4H-SiC), where a discrete barrier distribution can be considered. The same method is applied to inhomogeneous Pt/4H-SiC contacts. The forward characteristics measured at different temperatures are accurately reproduced using this inhomogeneous barrier model. A quasi-ideal behavior is identified for intervals spanning 200 °C for all measured Schottky samples, with Ni and Pt contact metals. A predictable exponential current-voltage variation over at least 2 orders of magnitude is also proven, with a stable barrier height and effective area for temperatures up to 400 °C. This application-oriented characterization technique is confirmed by using model parameters to fit a SiC-Schottky high temperature sensor's response.

  15. Nickel-gallium arsenide high-voltage power Schottky diodes

    Science.gov (United States)

    Ashkinazi, G.; Hadas, Tz.; Meyler, B.; Nathan, M.; Zolotarevski, L.; Zolotarevski, O.

    1993-01-01

    A power GaAs Schottky diode (SD) with a chemically deposited Ni barrier was designed, fabricated and tested. The diode has a reverse breakdown voltage VBR of 140 V, forward voltage drop VF (at 50 A/cm 2) of 0.7 V at 23°C, 0.5 V at 150°C and 0.3 V at 250°C, and reverse leakage current densities jR (at -50 V) of 0.1 μA/cm 2 at 23°C and 1 mA/cm 2 at 150°C. Calculated forward and reverse I- V characteristics using a simple self-consistent computer model are in good agreement with measured values. Calculated characteristics of a silicon SD with identical structure parameters, using the same model, show much poorer VBR, VF and jR values. The theoretical maximum value of VBR is physically limited by the largest allowed VF. For a V Fof ⋍1.6 V, V BR.maxis ⋍200 V in Si and ⋍800 simple technology allows manufacturing of large area GaAs Schottky diodes with average currents up to V in GaAs SDs. Our relatively 100 A.

  16. Modelling the inhomogeneous SiC Schottky interface

    Science.gov (United States)

    Gammon, P. M.; Pérez-Tomás, A.; Shah, V. A.; Vavasour, O.; Donchev, E.; Pang, J. S.; Myronov, M.; Fisher, C. A.; Jennings, M. R.; Leadley, D. R.; Mawby, P. A.

    2013-12-01

    For the first time, the I-V-T dataset of a Schottky diode has been accurately modelled, parameterised, and fully fit, incorporating the effects of interface inhomogeneity, patch pinch-off and resistance, and ideality factors that are both heavily temperature and voltage dependent. A Ni/SiC Schottky diode is characterised at 2 K intervals from 20 to 320 K, which, at room temperature, displays low ideality factors (n 8), voltage dependent ideality factors and evidence of the so-called "thermionic field emission effect" within a T0-plot, suggest significant inhomogeneity. Two models are used, each derived from Tung's original interactive parallel conduction treatment of barrier height inhomogeneity that can reproduce these commonly seen effects in single temperature I-V traces. The first model incorporates patch pinch-off effects and produces accurate and reliable fits above around 150 K, and at current densities lower than 10-5 A cm-2. Outside this region, we show that resistive effects within a given patch are responsible for the excessive ideality factors, and a second simplified model incorporating these resistive effects as well as pinch-off accurately reproduces the entire temperature range. Analysis of these fitting parameters reduces confidence in those fits above 230 K, and questions are raised about the physical interpretation of the fitting parameters. Despite this, both methods used are shown to be useful tools for accurately reproducing I-V-T data over a large temperature range.

  17. Gate tunable graphene-silicon Ohmic/Schottky contacts

    Science.gov (United States)

    Chen, Chun-Chung; Chang, Chia-Chi; Li, Zhen; Levi, A. F. J.; Cronin, Stephen B.

    2012-11-01

    We show that the I-V characteristics of graphene-silicon junctions can be actively tuned from rectifying to Ohmic behavior by electrostatically doping the graphene with a polymer electrolyte gate. Under zero applied gate voltage, we observe rectifying I-V characteristics, demonstrating the formation of a Schottky junction at the graphene-silicon interface. Through appropriate gating, the Fermi energy of the graphene can be varied to match the conduction or valence band of silicon, thus forming Ohmic contacts with both n- and p-type silicon. Over the applied gate voltage range, the low bias conductance can be varied by more than three orders of magnitude. By varying the top gate voltage from -4 to +4 V, the Fermi energy of the graphene is shifted between -3.78 and -5.47 eV; a shift of ±0.85 eV from the charge neutrality point. Since the conduction and valence bands of the underlying silicon substrate lie within this range, at -4.01 and -5.13 eV, the Schottky barrier height and depletion width can be decreased to zero for both n- and p-type silicon under the appropriate top gating conditions. I-V characteristics taken under illumination show that the photo-induced current can be increased or decreased based on the graphene-silicon work function difference.

  18. Characterization and Reliability of Vertical N-Type Gallium Nitride Schottky Contacts

    Science.gov (United States)

    2016-09-01

    fabricating ultra-pure, large diameter Si wafers has enabled rapid advancement in military technologies and consumer electronics; however, material...difference between the metal work function φM and the semiconductor electron affinity χ equals the Schottky barrier height φB : . (12...bandgap of GaN, approximately 3.3 eV, plus the electron affinity , approximately 1.5 eV. Second, the solubility of metals into gallium was taken into

  19. DC characteristics of the SiC Schottky diodes

    National Research Council Canada - National Science Library

    W Janke; A Hapka; M Oleksy

    2011-01-01

      DC characteristics of the SiC Schottky diodes The isothermal and non-isothermal characteristics of silicon carbide Schottky diodes in the wide range of currents and ambient temperatures are investigated in this paper...

  20. Electron Density and Capacitance at the interface of Au-ZnO Based Schottky Diode

    Science.gov (United States)

    Wu, Chin-Sheng

    ZnO with wide direct band gap (3.37 eV) is a well-known and an interesting compound semiconducting material, which have been used for the fabrication of optical, electrical, and piezoelectric devices such as light emitting diodes, solar cells. Schottky diodes are associated with quicker switching and lower turn on voltages compared to p-n junction diodes. J-V characteristics exhibit nonlinear rectifying behavior with threshold voltage of 2.1 V. The barrier heights were found to be 0.61 eV. The measured capacitance for the Schottky junction depends on the reverse bias potential and frequency. At the lower frequencies the capacitance has the higher values due to the trapping occurred at the interface through the surface roughness and lattice mismatch. We perform model potential calculation with quantum well around the interface. Model potentials allow some degree of freedom in the design of the emitted wavelength through adjustment of the energy levels. We apply the various well width w and barrier height V in order to match the device information made by Willander. Solving the Schrödinger equation with exchange- correlation energy and effective mass of electrons will produce values of the energy levels and states. The variational barrier heights result in the change of the electron density This accounts for the excessive capacitance at the interface of Schottky diode.

  1. Small signal thermal analysis of local multibarrier behaviour in SiC Schottky diodes

    Science.gov (United States)

    León, J.; Perpiñà, X.; Vellvehi, M.; Jordà, X.; Berthou, M.; Godignon, P.

    2014-09-01

    A nickel-based silicon carbide Schottky barrier diode presenting multibarrier behaviour was inspected by Small sIgnal Modulation for Thermal Analysis (SIMTA) to detect the weak spots responsible for this behaviour. SIMTA thermally modulates in frequency such weak spots with a small signal voltage while the device is electrically biased in an operating point of its static I/V curve (20 A-1 kV capability). This allows for quantitative studying of them in a thermal steady state as heat sources by lock-in thermography depending on the device operating regime. Using SIMTA, the barrier height and the area of each weak spot were determined by thermal means, yielding to an electrical model that fits the observed multibarrier behaviour. Results suggest that these spots were caused by surface areas of high density of states (due to 3C-SiC stacking faults) created during the wire bonding process, which locally shifted the Schottky barrier due to Fermi level pinning. Their origin was confirmed by scanning electron microscope inspections after milling these locations with a focused on beam, detecting Schottky metal contact degradation at weak spot locations due to an excessive bonding pressure.

  2. Semi-transparent SiC Schottky diodes for X-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lees, J.E. [Space Research Centre, Department of Physics and Astronomy, Michael Atiyah Building, University of Leicester, Leicester LE1 7RH (United Kingdom)]. E-mail: lee@star.le.ac.uk; Bassford, D.J. [Space Research Centre, Department of Physics and Astronomy, Michael Atiyah Building, University of Leicester, Leicester LE1 7RH (United Kingdom); Fraser, G.W. [Space Research Centre, Department of Physics and Astronomy, Michael Atiyah Building, University of Leicester, Leicester LE1 7RH (United Kingdom); Horsfall, A.B. [Semiconductor Technology Group, School of Electrical, Electronic and Computer Engineering, Merz Court, University of Newcastle, Newcastle NE1 7RU (United Kingdom); Vassilevski, K.V. [Semiconductor Technology Group, School of Electrical, Electronic and Computer Engineering, Merz Court, University of Newcastle, Newcastle NE1 7RU (United Kingdom); Wright, N.G. [Semiconductor Technology Group, School of Electrical, Electronic and Computer Engineering, Merz Court, University of Newcastle, Newcastle NE1 7RU (United Kingdom); Owens, A. [Office of Science Payload and Advanced Concepts, European Space Agency ESTEC SCI-A, Postbus 299, 2200AG Noordwijk (Netherlands)

    2007-07-21

    We describe a novel SiC Schottky diode architecture. The semi-transparent SiC Schottky diode has an 'ultra-thin' (18 nm Ni/Ti) Schottky contact, a gold annular overlayer and a gold corner-contact pad. We show that the new architecture exhibits the same essential characteristics as a more conventional 'thick-contact' Schottky diode ({>=}100 nm). Such diodes will have a higher efficiency for low-energy (<5 keV) X-rays than that of conventional structures combined with minimal self-fluorescence from the electrode materials. We present X-ray spectra from {sup 55}Fe, {sup 109}Cd and {sup 241}Am radioactive sources that show these diodes can be used for spectroscopy with promising energy resolution (1.47 keV FWHM at 22 keV) at room temperature (23 {sup o}C). The reduction in contact thickness, however, does reduce the barrier height of the new diodes in comparison to those fabricated using the conventional process, and requires a trade-off between the low-energy detection threshold and the noise in the detector.

  3. Electrical characterization of MEH-PPV based Schottky diodes

    Energy Technology Data Exchange (ETDEWEB)

    Nimith, K. M., E-mail: nimithkm@gmail.com; Satyanarayan, M. N., E-mail: satya-mn@nitk.edu.in; Umesh, G., E-mail: umesh52@gmail.com [Optoelectronics Laboratory (OEL), Department of Physics, National Institute of Technology Karnataka (NITK),Surathkal, PO Srinivasnagar, Mangalore, DK-575025 (India)

    2016-05-06

    MEH-PPV Schottky diodes with and without Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) have been fabricated and characterized. The highlight of this work is that all the fabrication and characterization steps had been carried out in the ambient conditions and the device fabrication was done without any UV-Ozone surface treatment of ITO anodes. Current Density-Voltage characteristics shows that the addition of hole injection layer (HIL) enhances the charge injection into the polymer layer by reducing the energy barrier across the Indium Tin Oxide (ITO)-Organic interface. The rectification ratio increases to 2.21 from 0.76 at 5V for multilayer devices compared to single layer devices. Further we investigated the effect of an alkali metal fluoride (LiF) by inserting a thin layer in between the organic layer and Aluminum (Al) cathode. The results of these investigations will be discussed in detail.

  4. Electrical characterization of MEH-PPV based Schottky diodes

    Science.gov (United States)

    Nimith, K. M.; Satyanarayan, M. N.; Umesh, G.

    2016-05-01

    MEH-PPV Schottky diodes with and without Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) have been fabricated and characterized. The highlight of this work is that all the fabrication and characterization steps had been carried out in the ambient conditions and the device fabrication was done without any UV-Ozone surface treatment of ITO anodes. Current Density-Voltage characteristics shows that the addition of hole injection layer (HIL) enhances the charge injection into the polymer layer by reducing the energy barrier across the Indium Tin Oxide (ITO)-Organic interface. The rectification ratio increases to 2.21 from 0.76 at 5V for multilayer devices compared to single layer devices. Further we investigated the effect of an alkali metal fluoride (LiF) by inserting a thin layer in between the organic layer and Aluminum (Al) cathode. The results of these investigations will be discussed in detail.

  5. Lateral IBIC analysis of GaAs Schottky diodes

    Energy Technology Data Exchange (ETDEWEB)

    Vittone, E. [Experimental Physics Department, ' Nanostructured interfaces and surfaces' (NIS) Centre of Excellence of the University of Torino, and INFN - Torino (Italy) and INFM, Research Unit of Torino-University, Via P. Giuria 1, 10125 Torino (Italy)]. E-mail: vittone@to.infn.it; Olivero, P. [Experimental Physics Department, ' Nanostructured interfaces and surfaces' (NIS) Centre of Excellence of the University of Torino, and INFN - Torino (Italy) and INFM, Research Unit of Torino-University, Via P. Giuria 1, 10125 Torino (Italy)]. E-mail: p.olivero@physics.unimelb.edu.au; Nava, F. [INFN and Departimento di Fisica, Universita di Modena e Reggio Emilia, Via Campi, 213/A - 41100 Modena (Italy); Manfredotti, C. [Experimental Physics Department, ' Nanostructured interfaces and surfaces' (NIS) Centre of Excellence of the University of Torino, and INFN - Torino (Italy); INFM, Research Unit of Torino-University, Via P. Giuria 1, 10125 Torino (Italy); Lo Giudice, A. [INFM, Research Unit of Torino-University, Via P. Giuria 1, 10125 Torino (Italy); Fizzotti, F. [Experimental Physics Department, ' Nanostructured interfaces and surfaces' (NIS) Centre of Excellence of the University of Torino, and INFN - Torino (Italy); INFM, Research Unit of Torino-University, Via P. Giuria 1, 10125 Torino (Italy); Egeni, G. [INFN - Laboratori Nazionali di Legnaro, Viale dell' Universita 2, 35020 Legnaro (Pd) (Italy)

    2005-04-01

    Charge collection efficiency (CCE) profiles of a semi-insulating (SI) gallium arsenide LEC (Liquid Encapsulated Czochralski) Schottky diode have been investigated by lateral Ion Beam Induced Charge collection (IBIC) technique. A focussed 2.4 MeV proton microbeam was scanned over the cleaved surface of a SI-GaAs diode and the charge collection efficiency was evaluated as a function of the ion beam position at different bias voltages. By fitting the CCE profiles with the equations derived by the Shockley-Ramo-Gunn's theorem, drift lengths of electrons and holes were obtained. Experimental results are consistent with previous OBIC (Optical Beam Induced Current) and SP (Surface Potential) measurements and confirm the model based on the formation of a Mott barrier due to the enhanced electron capture cross section in high field conditions.

  6. SiC polytypes and doping nature effects on electrical properties of ZnO-SiC Schottky diodes

    OpenAIRE

    Rebaoui, Z.; Bouiajra, W.B.; Abboun Abid, M.; Saidane, A.; Jameel, D.; HENINI, M.; Felix, J. F.

    2017-01-01

    Electrical properties of ZnO/SiC Schottky diodes with two SiC polytypes and N and P doping are investigated. Characterization was performed through I–V and C–V–f measurements. Schottky barrier height (Φb), ideality factor (n), and series resistance (Rs) were extracted from forward I–V characteristics. (Φb), carrier’s concentrations (Nd-Na) and (Rs) frequency dependence were extracted from C–V–f characteristics. The extracted n values suggest that current transport is dominated by interface ge...

  7. Simulation and comparative study of tunneling field effect transistors with dopant-segregated Schottky source/drain

    Science.gov (United States)

    Zhang, Yi Bo; Sun, Lei; Xu, Hao; Han, Jing Wen

    2016-04-01

    Dopant-segregated Schottky source/drain tunneling field effect transistors (STFET) are investigated in this paper. The working mechanisms of STFET and the influence of device parameters are studied with Synopsys Sentaurus. Schottky source/drain MOSFETs possess several advantages over conventional MOSFETs, and dopant segregation can be feasibly achieved within current silicidation process. With dopant segregation, highly doped regions can be obtained after silicidation, which is necessary for band-to-band tunneling. With proper parameter setting, STFET can achieve comparable performance as TFET. High segregation doping for STFET is required to increase band-to-band tunneling probability and suppress bipolar behaviors. Increasing the electron barrier height at source side helps to provide larger drive current and higher on/off ratio. It is also found that STFET’s on-state performance is irrelevant to the segregation length when the segregation length is larger than a certain value. Furthermore, STFET is also insensitive to the Schottky barrier at drain side when the Schottky barrier at source side is fixed, which would relax the requirement for source/drain fabrication.

  8. Current Transport Behaviour of Au/n-GaAs Schottky Diodes Grown on Ge Substrate With Different Epitaxial Layer Thickness Over a Wide Temperature Range

    Directory of Open Access Journals (Sweden)

    N. Padha

    2011-01-01

    Full Text Available The work presents temperature dependent forward and reverse current-voltage (I-V analyses of n-GaAs/Au Schottky Diodes grown on n+ Ge substrate with different epitaxial layer thicknesses. While some of the Schottky diodes follow TED mechanism, others exceed significantly from this theory due to existence of patches of reduced barrier height embedded in the Schottky interface. The zero bias barrier heights (φbo increase (0.649 to 0.809 eV while the ideality factors (η decrease (1.514 to 1.052 with increase in epitaxial layer thickness (1-4 μm, thus, indicating similar behaviour to that observed for the I-V characteristics of the undertaken Schottky diodes with decreasing temperature. It all indicated the existence of barrier inhomogenities over the M-S interface. The breakdown behaviour analysis of these diodes showed some interesting results; the breakdown voltage (VBR decreases with temperature and shows ‘Defect Assisted Tunneling’ phenomenon through surface or defect states in the 1 μm thick epitaxial layer Schottky diode while VBR increases with temperature in 3 μm and 4 μm thick epitaxial layer Schottky diodes which demonstrate ‘Avalanche Multiplication’ mechanism responsible for junction breakdown. The reverse breakdown voltage is also seen to increase (2.7-5.9 Volts with the increase in epitaxial layer thickness of the diodes. The undertaken diodes have been observed to follow TFE mechanism at low temperatures (below 200 K in which the tunneling current component increases with epitaxial layer thickness which has been ascribed as an impact of GaAs/Ge hetero-interface over the Au/n-GaAs Schottky barrier.

  9. Evidence of minority carrier injection efficiency >90% in an epitaxial graphene/SiC Schottky emitter bipolar junction phototransistor for ultraviolet detection

    Energy Technology Data Exchange (ETDEWEB)

    Chava, Venkata S. N., E-mail: vchava@email.sc.edu; Omar, Sabih U.; Brown, Gabriel; Shetu, Shamaita S.; Andrews, J.; Sudarshan, T. S.; Chandrashekhar, M. V. S. [Department of Electrical Engineering, University of South Carolina, Columbia, South Carolina 29208 (United States)

    2016-01-25

    In this letter, we report the UV detection characteristics of an epitaxial graphene (EG)/SiC based Schottky emitter bipolar phototransistor (SEPT) with EG on top as the transparent Schottky emitter layer. Under 0.43 μW UV illumination, the device showed a maximum common emitter current gain of 113, when operated in the Schottky emitter mode. We argue that avalanche gain and photoconductive gain can be excluded, indicating minority carrier injection efficiency, γ, as high as 99% at the EG/p-SiC Schottky junction. This high γ is attributed to the large, highly asymmetric barrier, which EG forms with the p-SiC. The maximum responsivity of the UV phototransistor is estimated to be 7.1 A/W. The observed decrease in gain with increase in UV power is attributed to recombination in the base region, which reduces the minority carrier lifetime.

  10. Control of pn-junction turn-on voltage in 4H-SiC merged PiN Schottky diode

    Science.gov (United States)

    Park, Junbo; Park, Kun-Sik; Won, Jong-il; Kim, Ki-hwan; Koo, Sangmo; Kim, Sang-gi; Mun, Jae-Kyoung

    2017-04-01

    We present numerical simulation results and experimental measurements that explain the physical mechanism behind the high critical voltage, Vcrit, required to turn on a pn junction in a merged PiN Schottky (MPS) diode. The 2D simulation of potential distribution within a unit MPS cell demonstrated that the potential gradient set by the Schottky junction raises the potential barrier formed at the pn junction, thereby increasing Vcrit. Based on this knowledge, we propose that changing the ratio of the Schottky contact and the p+ region area, as well as shallow p-doping of the Schottky interface, can be used to control the magnitude of Vcrit. We present simulation and measurement results that demonstrate the feasibility of our approach.

  11. Evidence of minority carrier injection efficiency >90% in an epitaxial graphene/SiC Schottky emitter bipolar junction phototransistor for ultraviolet detection

    Science.gov (United States)

    Chava, Venkata S. N.; Omar, Sabih U.; Brown, Gabriel; Shetu, Shamaita S.; Andrews, J.; Sudarshan, T. S.; Chandrashekhar, M. V. S.

    2016-01-01

    In this letter, we report the UV detection characteristics of an epitaxial graphene (EG)/SiC based Schottky emitter bipolar phototransistor (SEPT) with EG on top as the transparent Schottky emitter layer. Under 0.43 μW UV illumination, the device showed a maximum common emitter current gain of 113, when operated in the Schottky emitter mode. We argue that avalanche gain and photoconductive gain can be excluded, indicating minority carrier injection efficiency, γ, as high as 99% at the EG/p-SiC Schottky junction. This high γ is attributed to the large, highly asymmetric barrier, which EG forms with the p-SiC. The maximum responsivity of the UV phototransistor is estimated to be 7.1 A/W. The observed decrease in gain with increase in UV power is attributed to recombination in the base region, which reduces the minority carrier lifetime.

  12. Fabrication and Characterization of n-AlGaAs/GaAs Schottky Diode for Rectenna Device Application

    Science.gov (United States)

    Parimon, Norfarariyanti; Mustafa, Farahiyah; Manaf Hashim, Abdul; Fadzli Abd Rahman, Shaharin; Rahman, Abdul Rahim Abdul; Nizam Osman, Mohd

    2011-02-01

    Schottky diode was designed and fabricated on n-AlGaAs/GaAs high electron mobility transistor (HEMT) structure for rectenna device application. Rectenna is one of the most potential devices to form the wireless power supply which is really good at converting microwaves to DC. The processing steps used in the fabrication of Schottky diode were the conventional steps used in standard GaAs processing. Current-voltage (I-V) measurements showed that the device had rectifying properties with a barrier height of 0.5468 eV for Ni/Au metallization. The fabricated Schottky diode detected RF signals and the cut-off frequency up to 20 GHz was estimated in direct injection experiments. These preliminary results will provide a breakthrough for the direct integration with antenna towards realization of rectenna device application.

  13. Fabrication and Characterization of n-AlGaAs/GaAs Schottky Diode for Rectenna Device Application

    Energy Technology Data Exchange (ETDEWEB)

    Parimon, Norfarariyanti; Mustafa, Farahiyah; Hashim, Abdul Manaf; Rahman, Shaharin Fadzli Abd; Rahman, Abdul Rahim Abdul [Material Innovations and Nanoelectronics Research Group, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Osman, Mohd Nizam, E-mail: manaf@fke.utm.my [Telekom Research and Development, TM Innovation Centre, 63000 Cyberjaya (Malaysia)

    2011-02-15

    Schottky diode was designed and fabricated on n-AlGaAs/GaAs high electron mobility transistor (HEMT) structure for rectenna device application. Rectenna is one of the most potential devices to form the wireless power supply which is really good at converting microwaves to DC. The processing steps used in the fabrication of Schottky diode were the conventional steps used in standard GaAs processing. Current-voltage (I-V) measurements showed that the device had rectifying properties with a barrier height of 0.5468 eV for Ni/Au metallization. The fabricated Schottky diode detected RF signals and the cut-off frequency up to 20 GHz was estimated in direct injection experiments. These preliminary results will provide a breakthrough for the direct integration with antenna towards realization of rectenna device application.

  14. Sum Frequency Generation Vibrational Spectroscopy of 1,3-Butadiene Hydrogenation on 4 nm Pt@SiO 2 , Pd@SiO 2 , and Rh@SiO 2 Core–Shell Catalysts

    KAUST Repository

    Krier, James M.

    2015-01-14

    © 2014 American Chemical Society. 1,3-Butadiene (1,3-BD) hydrogenation was performed on 4 nm Pt, Pd, and Rh nanoparticles (NPs) encapsulated in SiO2 shells at 20, 60, and 100 °C. The core-shells were grown around polyvinylpyrrolidone (PVP) coated NPs (Stöber encapsulation) prepared by colloidal synthesis. Sum frequency generation (SFG) vibrational spectroscopy was performed to correlate surface intermediates observed in situ with reaction selectivity. It is shown that calcination is effective in removing PVP, and the SFG signal can be generated from the metal surface. Using SFG, it is possible to compare the surface vibrational spectrum of Pt@SiO2 (1,3-BD is hydrogenated through multiple paths and produces butane, 1-butene, and cis/trans-2-butene) to Pd@SiO2 (1,3-BD favors one path and produces 1-butene and cis/trans-2-butene). In contrast to Pt@SiO2 and Pd@SiO2, SFG and kinetic experiments of Rh@SiO2 show a permanent accumulation of organic material.

  15. 2-D Design of Schottky Diodes

    Science.gov (United States)

    2000-09-29

    Schottky diode with- Lb, rse = 2.5 ,im as can be observed in figure 3. 25 ........... ...... ..... Series roi~ttarce for *ý,,,,-io irm. Ii bsai.10in 0...epitaxial layer Wp ( rse < 𔃽 -4), which is typical 4D0 ............. . . for submillimeter varactors. Of course, the influence of the .............. ~ L

  16. Application of superconductor-semiconductor Schottky barrier for electron cooling

    Energy Technology Data Exchange (ETDEWEB)

    Savin, Alexander; Prunnila, Mika; Ahopelto, Jouni; Kivinen, Pasi; Toermae, Paeivi; Pekola, Jukka

    2003-05-01

    Electronic cooling in superconductor-semiconductor-superconductor structures at sub kelvin temperatures has been demonstrated. Effect of the carrier concentration in the semiconductor on performance of the micro-cooler has been investigated.

  17. Electrical Characterization of Defects in SiC Schottky Barriers

    Science.gov (United States)

    Schnabel, C. M.; Tabib-Azar, M.; Raffaelle, R. P.; Su, H. B.; Dudley, M.; Neudeck, P. G.; Bailey, S.

    2005-01-01

    We have been investigating the effect of screw dislocation and other structural defects on the electrical properties of SiC. SiC is a wide-bandgap semiconductor that is currently received much attention due to its favorable high temperature behavior and high electric field breakdown strength. Unfortunately, the current state-of-the-art crystal growth and device processing methods produce material with high defect densities, resulting in a limited commercial viability

  18. Analytical modeling of Schottky tunneling source impact ionization MOSFET with reduced breakdown voltage

    Directory of Open Access Journals (Sweden)

    Sangeeta Singh

    2016-03-01

    Full Text Available In this paper, we have investigated a novel Schottky tunneling source impact ionization MOSFET (STS-IMOS to lower the breakdown voltage of conventional impact ionization MOS (IMOS and developed an analytical model for the same. In STS-IMOS there is an accumulative effect of both impact ionization and source induced barrier tunneling. The silicide source offers very low parasitic resistance, the outcome of which is an increment in voltage drop across the intrinsic region for the same applied bias. This reduces operating voltage and hence, it exhibits a significant reduction in both breakdown and threshold voltage. STS-IMOS shows high immunity against hot electron damage. As a result of this the device reliability increases magnificently. The analytical model for impact ionization current (Iii is developed based on the integration of ionization integral (M. Similarly, to get Schottky tunneling current (ITun expression, Wentzel–Kramers–Brillouin (WKB approximation is employed. Analytical models for threshold voltage and subthreshold slope is optimized against Schottky barrier height (ϕB variation. The expression for the drain current is computed as a function of gate-to-drain bias via integral expression. It is validated by comparing it with the technology computer-aided design (TCAD simulation results as well. In essence, this analytical framework provides the physical background for better understanding of STS-IMOS and its performance estimation.

  19. Weak Fermi Level Pinning Effect in Schottky Junction of α-MoTe2

    Science.gov (United States)

    Nakaharai, Shu; Yamamoto, Mahito; Ueno, Keiji; Tsukagoshi, Kazuhito

    Difficulty in hole injection from metal contacts to transition metal dichalcogenide (TMDC) semiconductors has been one of the most serious issues in the application of these 2D materials to future nanoelectronics, which is caused by the strong Fermi level pinning effect in the metal/TMDC Schottky junction. In this work, we found that the holes can be injected efficiently from a large work function metal of Pt to α-molybdenum ditelluride (α-MoTe2; 2H-type), a TMDC semiconductor. The Schottky barrier height for holes at the Pt/ α-MoTe2 interface was extracted to be 40 meV by the temperature dependence of back-gate modulated currents under the flat band condition at the junction, while the Schottky barrier for electrons in the junction with a small work function metal of Ti was found to be 50 meV. Considering the difference in the work functions of Pt and Ti, the Fermi level pinning effect in α-MoTe2 was found to be much weaker than that in other TMDC semiconductors such as MoS2. These results open a way to the realization of complementary type circuits in the 2D materials for future low-power consumption electronics. This work was supported by JSPS KAKENHI Grant Numbers 15K06006, 25107004.

  20. Performance assessment of nanoscale Schottky MOSFET as resonant tunnelling device: Non-equilibrium Green’s function formalism

    Indian Academy of Sciences (India)

    Zahra Ahangari; Morteza Fathipour

    2013-09-01

    A comprehensive study is performed on the electrical characteristics of Schottky barrier MOSFET (SBMOSFET) in nanoscale regime, by employing the non-equilibrium Green’s function (NEGF) approach. Quantum confinement results in the enhancement of effective Schottky barrier height (SBH). High enough Schottky barriers at the source/drain and the channel form a double barrier profile along the channel that results in the formation of resonance states. We have, for the first time, proposed a resonant tunnelling device based on SBMOSFET in which multiple resonance states are modulated by the gate voltage. Role of essential factors such as temperature, SBH, bias voltage and structural parameters on the feasibility of this device for silicon-based resonant tunnelling applications are extensively studied. Resonant tunnelling appears at low temperatures and low drain voltages and as a result negative differential resistance (NDR) is apparent in the transfer characteristic. Scaling down the gate length to 6 nm increases the peak-to-valley ratio (PVR) of the drain current. As the effective SBH reduces, the curvature of the double barrier profile is gradually diminished. Therefore, multiple resonant states are contributed to the current and consequently resonant tunnelling is smoothed out.

  1. The investigation of nanoscale effects on schottky interfaces and the scattering rates of high resistivity metals

    Science.gov (United States)

    Durcan, Christopher

    Understanding the transport of electrons through materials and across interfaces is fundamental to modern day electronics. As electrons travel, interactions with defects within the crystal lattice induce scattering which gives rise to resistivity. At the interface between two materials, electrostatic barriers exist which can impede the flow of electrons. The work of this thesis is to further the understanding of electron transport by measuring the transport across metal-semiconductor interfaces at the nanoscale and measure scattering phenomena in metals. The measurement technique ballistic electron emission microscopy (BEEM) was used due to its ability to probe the scattering processes within a metal film and across metal semiconductor interfaces with nanoscale resolution. It was discovered that the hot electron transmission of the W/Si(001) Schottky barrier decreases over a period of 21 days with the initial Schottky barrier height of 0.71eV decreasing to 0.62eV. The spatial map changes dramatically from 98% of the spectra able to be fit to only 27%. This is supported by transmission electron microscopy (TEM) showing the formation of a tungsten silicide which increases in thickness. It was discovered that the deposition of tungsten on silicon using electron beam evaporation and RF magnetron sputtering resulted in dramatic differences in the Schottky barrier height and transport of hot electrons. A difference of ˜70meV was measured in the Schottky barrier height's for both p-type and n-type silicon. Spatial maps show a uniform barrier height for the sputter film and varying barrier height for the e-beam film. Histograms show a symmetric gaussian profile for the sputtered film and an asymmetric profile for the evaporated film, arising from an increase in elastic scattering. The hot electron attenuation length of tungsten and chromium thin films were measured on Si(001) and Si(111) substrates. An attenuation length of 2.26nm was measured at 1.0V bias for tungsten

  2. Operation regimes and electrical transport of steep slope Schottky Si-FinFETs

    Science.gov (United States)

    Jeon, Dae-Young; Zhang, Jian; Trommer, Jens; Park, So Jeong; Gaillardon, Pierre-Emmanuel; De Micheli, Giovanni; Mikolajick, Thomas; Weber, Walter M.

    2017-02-01

    In the quest for energy efficient circuits, considerable focus has been given to steep slope and polarity-controllable devices, targeting low supply voltages and reduction of transistor count. The recently proposed concept of the three-independent gated Si-FinFETs with Schottky-barriers (SBs) has proven to bring both functionalities even in a single device. However, the complex combination of transport properties including Schottky emission and weak impact ionization as well as the body effect makes the design of such devices challenging. In this work, we perform a deep electrical characterization analysis to visualize and decouple the different operation regimes and electrical properties of the SB Si-FinFETs using a graphical transport map. From these, we give important guidelines for the design of future devices.

  3. A graphene barristor using nitrogen profile controlled ZnO Schottky contacts.

    Science.gov (United States)

    Hwang, Hyeon Jun; Chang, Kyoung Eun; Yoo, Won Beom; Shim, Chang Hoo; Lee, Sang Kyung; Yang, Jin Ho; Kim, So-Young; Lee, Yongsu; Cho, Chunhum; Lee, Byoung Hun

    2017-02-16

    We have successfully demonstrated a graphene-ZnO:N Schottky barristor. The barrier height between graphene and ZnO:N could be modulated by a buried gate electrode in the range of 0.5-0.73 eV, and an on-off ratio of up to 10(7) was achieved. By using a nitrogen-doped ZnO film as a Schottky contact material, the stability problem of previously reported graphene barristors could be greatly alleviated and a facile route to build a top-down processed graphene barristor was realized with a very low heat cycle. This device will be instrumental when implementing logic functions in systems requiring high-performance logic devices fabricated with a low temperature fabrication process such as back-end integrated logic devices or flexible devices on soft substrates.

  4. Modulation of electrical properties in Cu/n-type InP Schottky junctions using oxygen plasma treatment

    Science.gov (United States)

    Kim, Hogyoung; Cho, Yunae; Jung, Chan Yeong; Kim, Se Hyun; Kim, Dong-Wook

    2015-12-01

    Using current-voltage (I-V) measurements, we investigated the effect of oxygen plasma treatment on the temperature-dependent electrical properties of Cu/n-type indium phosphide (InP) Schottky contacts at temperatures in the range 100-300 K. Changes in the electrical parameters were evident below 180 K for the low-plasma-power sample (100 W), which is indicative of the presence of a wider distribution of regions of low barrier height. Modified Richardson plots were used to obtain Richardson constants, which were similar to the theoretical value of 9.4 A cm-2 K-2 for n-type InP. This suggests that, for all the samples, a thermionic emission model including a spatially inhomogeneous Schottky barrier can be used to describe the charge transport phenomena at the metal/semiconductor interface. The voltage dependence of the reverse-bias current revealed that Schottky emission was dominant for the untreated and high-plasma-power (250 W) samples. For the low-plasma-power sample, Poole-Frenkel emission was dominant at low voltages, whereas Schottky emission dominated at higher voltages. Defect states and nonuniformity of the interfacial layer appear to be significant in the reverse-bias charge transport properties of the low-plasma-power sample.

  5. Schottky diodes from 2D germanane

    Science.gov (United States)

    Sahoo, Nanda Gopal; Esteves, Richard J.; Punetha, Vinay Deep; Pestov, Dmitry; Arachchige, Indika U.; McLeskey, James T.

    2016-07-01

    We report on the fabrication and characterization of a Schottky diode made using 2D germanane (hydrogenated germanene). When compared to germanium, the 2D structure has higher electron mobility, an optimal band-gap, and exceptional stability making germanane an outstanding candidate for a variety of opto-electronic devices. One-atom-thick sheets of hydrogenated puckered germanium atoms have been synthesized from a CaGe2 framework via intercalation and characterized by XRD, Raman, and FTIR techniques. The material was then used to fabricate Schottky diodes by suspending the germanane in benzonitrile and drop-casting it onto interdigitated metal electrodes. The devices demonstrate significant rectifying behavior and the outstanding potential of this material.

  6. Schottky diodes from 2D germanane

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, Nanda Gopal; Punetha, Vinay Deep [Nanoscience and Nanotechnology Centre, Department of Chemistry, Kumaun University, Nainital, 263001 Uttarakhand (India); Esteves, Richard J; Arachchige, Indika U. [Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Pestov, Dmitry [Nanomaterials Core Characterization Center, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); McLeskey, James T., E-mail: JamesMcLeskey@rmc.edu [Department of Physics, Randolph-Macon College, Ashland, Virginia 23005 (United States)

    2016-07-11

    We report on the fabrication and characterization of a Schottky diode made using 2D germanane (hydrogenated germanene). When compared to germanium, the 2D structure has higher electron mobility, an optimal band-gap, and exceptional stability making germanane an outstanding candidate for a variety of opto-electronic devices. One-atom-thick sheets of hydrogenated puckered germanium atoms have been synthesized from a CaGe{sub 2} framework via intercalation and characterized by XRD, Raman, and FTIR techniques. The material was then used to fabricate Schottky diodes by suspending the germanane in benzonitrile and drop-casting it onto interdigitated metal electrodes. The devices demonstrate significant rectifying behavior and the outstanding potential of this material.

  7. Tunable reverse-biased graphene/silicon heterojunction Schottky diode sensor.

    Science.gov (United States)

    Singh, Amol; Uddin, Ahsan; Sudarshan, Tangali; Koley, Goutam

    2014-04-24

    A new chemical sensor based on reverse-biased graphene/Si heterojunction diode has been developed that exhibits extremely high bias-dependent molecular detection sensitivity and low operating power. The device takes advantage of graphene's atomically thin nature, which enables molecular adsorption on its surface to directly alter graphene/Si interface barrier height, thus affecting the junction current exponentially when operated in reverse bias and resulting in ultrahigh sensitivity. By operating the device in reverse bias, the work function of graphene, and hence the barrier height at the graphene/Si heterointerface, can be controlled by the bias magnitude, leading to a wide tunability of the molecular detection sensitivity. Such sensitivity control is also possible by carefully selecting the graphene/Si heterojunction Schottky barrier height. Compared to a conventional graphene amperometric sensor fabricated on the same chip, the proposed sensor demonstrated 13 times higher sensitivity for NO₂ and 3 times higher for NH₃ in ambient conditions, while consuming ∼500 times less power for same magnitude of applied voltage bias. The sensing mechanism based on heterojunction Schottky barrier height change has been confirmed using capacitance-voltage measurements.

  8. Influence of rapid thermal annealing effect on electrical and structural properties of Pd/Ru Schottky contacts to n-type GaN

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, N. Nanda Kumar [Department of Physics, Sri Venkateswara University, Tirupati 517 502 (India); Reddy, V. Rajagopal, E-mail: reddy_vrg@rediffmail.com [Department of Physics, Sri Venkateswara University, Tirupati 517 502 (India); Choi, Chel-Jong [School of Semiconductor and Chemical Engineering, Semiconductor Physics Research Center (SPRC), Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

    2011-11-01

    Highlights: {yields} Annealing effects on the electrical and structural properties of Ru/Pd/n-GaN SBDs are studied. {yields} The optimum annealing temperature for Pd/Ru Schottky contact is 300 deg. C. {yields} Increase in SBH upon annealing at 300 deg. C could be attributed to the formation of gallide phases. {yields} The overall surface morphology of the Pd/Ru Schottky contacts on n-GaN is fairly smooth. - Abstract: Pd/Ru metallization scheme is fabricated on n-GaN as a Schottky contact, and the electrical and structural properties have been investigated as a function of annealing temperature by current-voltage (I-V), capacitance-voltage (C-V), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) measurements. As-deposited Ru/Pd/n-GaN contact yielded Schottky barrier height (SBH) of 0.67 eV (I-V) and 0.79 eV (C-V), respectively. Further, it is observed that the Schottky barrier height increases to 0.80 eV (I-V) and 0.96 eV (C-V) for the contact annealed at 300 deg. C. However, both I-V and C-V measurements indicate that the barrier height slightly decreased when the contacts are annealed at 400 deg. C and 500 deg. C. From the above observations, the optimum annealing temperature for Pd/Ru Schottky contact is 300 deg. C. Norde method is also employed to extract the barrier height of Pd/Ru Schottky contacts which are in good agreement with those obtained by the I-V technique. X-ray photoelectron spectroscopy results shows that the Ga 2p core-level shift towards the low-energy side for the contact annealed at 300 deg. C compared to the as-deposited contact. Based on the XPS and XRD results, the reason for the increase in SBH upon annealing at 300 deg. C could be attributed to the formation of gallide phases at the Ru/Pd/n-GaN interface vicinity. The AFM results showed that the overall surface morphology of the Pd/Ru Schottky contacts on n-GaN is fairly smooth. The above observations reveal that the Pd/Ru Schottky contact is attractive for high

  9. Gallium Nitride Schottky betavoltaic nuclear batteries

    Energy Technology Data Exchange (ETDEWEB)

    Lu Min, E-mail: mlu2006@sinano.ac.c [Su zhou Institute of Nano-technology and Nano-bionics, CAS, Su zhou 215125 (China); Zhang Guoguang [China Institute of Atomic Energy, Beijing 102413 (China); Fu Kai; Yu Guohao [Su zhou Institute of Nano-technology and Nano-bionics, CAS, Su zhou 215125 (China); Su Dan; Hu Jifeng [China Institute of Atomic Energy, Beijing 102413 (China)

    2011-04-15

    Research highlights: {yields} Gallium Nitride nuclear batteries with Ni-63 are demonstrated for the first time. {yields} Open circuit voltage of 0.1 V and conversion efficiency of 0.32% have been obtained. {yields} The limited performance is due to thin effective energy deposition layer. {yields} The output power is expected to greatly increase with growing thick GaN films. -- Abstract: Gallium Nitride (GaN) Schottky betavoltaic nuclear batteries (GNBB) are demonstrated in our work for the first time. GaN films are grown on sapphire substrates by metalorganic chemical vapor deposition (MOCVD), and then GaN Schottky diodes are fabricated by normal micro-fabrication process. Nickel with mass number of 63 ({sup 63}Ni), which emits {beta} particles, is loaded on the GaN Schottky diodes to achieve GNBB. X-ray diffraction (XRD) and photoluminescence (PL) are carried out to investigate the crystal quality for the GaN films as grown. Current-voltage (I-V) characteristics shows that the GaN Schottky diodes are not jet broken down at -200 V due to consummate fabrication processes, and the open circuit voltage of the GNBB is 0.1 V and the short circuit current density is 1.2 nA cm{sup -2}. The limited performance of the GNBB is due to thin effective energy deposition layer, which is only 206 nm to absorb very small partial energy of the {beta} particles because of the relatively high dislocation density and carrier concentration. However, the conversion efficiency of 0.32% and charge collection efficiency (CCE) of 29% for the GNBB have been obtained. Therefore, the output power of the GNBB are expected to greatly increase with growing high quality thick GaN films.

  10. SiC Schottky diode electrothermal macromodel

    OpenAIRE

    Masana Nadal, Francisco

    2010-01-01

    This paper presents a SiC Schottky diode model including static, dynamic and thermal features implemented as separate parameterized blocks constructed from SPICE Analog Behavioral Modeling (ABM) controlled sources. The parameters for each block are easy to extract, even from readily available diode data sheet information. The model complexity is low thus allowing reasonably long simulation times to cope with the rather slow self heating process and yet accurate enough for practical purposes.

  11. Planar Schottky technology for submillimeter wavelengths

    Science.gov (United States)

    Crowe, Thomas W.; Bishop, William L.; Hesler, Jeffrey L.; Marazita, Steven M.; Koh, Philip J.; Porterfield, David W.

    1996-01-01

    Work carried out in relation to the development of planar integrated Schottky diodes with the aim of increasing the sensitivity, reliability and efficiency of spaceborne heterodyne receivers, is reported. The results of this work include a planar diode mixer at 585 GHz with a total receiver noise temperature of 2,380 K double side band, and planar diode multipliers. The prospects for further integration of circuit elements with the GaAs diodes are discussed.

  12. Revised diode equation for Ideal Graphene-Semiconductor Schottky Junction

    OpenAIRE

    Liang, Shi-Jun; Ang, Lay Kee

    2015-01-01

    In this paper we carry out a theoretical and experimental study of the nature of graphene/semiconductor Schottky contact. We present a simple and parameter-free carrier transport model of graphene/semiconductor Schottky contact derived from quantum statistical theory, which is validated by the quantum Landauer theory and first-principle calculations. The proposed model can well explain experimental results for samples of different types of graphene/semiconductor Schottky contact.

  13. Organic modification of metal / semiconductor Schottky contacts

    Energy Technology Data Exchange (ETDEWEB)

    Mendez Pinzon, H.A.

    2006-07-10

    In the present work a Metal / organic / inorganic semiconductor hybrid heterostructure (Ag / DiMe-PTCDI / GaAs) was built under UHV conditions and characterised in situ. The aim was to investigate the influence of the organic layer in the surface properties of GaAs(100) and in the electrical response of organic-modified Ag / GaAs Schottky diodes. The device was tested by combining surface-sensitive techniques (Photoemission spectroscopy and NEXAFS) with electrical measurements (current-voltage, capacitance-voltage, impedance and charge transient spectroscopies). Core level examination by PES confirms removal of native oxide layers on sulphur passivated (S-GaAs) and hydrogen plasma treated GaAs(100) (H+GaAs) surfaces. Additional deposition of ultrathin layers of DiMe-PTCDI may lead to a reduction of the surface defects density and thereby to an improvement of the electronic properties of GaAs. The energy level alignment through the heterostructure was deduced by combining UPS and I-V measurements. This allows fitting of the I-V characteristics with electron as majority carriers injected over a barrier by thermionic emission as a primary event. For thin organic layers (below 8 nm thickness) several techniques (UPS, I-V, C-V, QTS and AFM) show non homogeneous layer growth, leading to formation of voids. The coverage of the H+GaAs substrate as a function of the nominal thickness of DiMe-PTCDI was assessed via C-V measurements assuming a voltage independent capacitance of the organic layer. The frequency response of the device was evaluated through C-V and impedance measurements in the range 1 kHz-1 MHz. The almost independent behaviour of the capacitance in the measured frequency range confirmed the assumption of a near geometrical capacitor, which was used for modelling the impedance with an equivalent circuit of seven components. From there it was found a predominance of the space charge region impedance, so that A.C. conduction can only takes place through the

  14. PtSi红外探测器截止波长延长研究%Study on Extension of Cut-off Wavelength of PtSi Infrared Detectors

    Institute of Scientific and Technical Information of China (English)

    刘爽; 杨家德; 刘飒; 宁永功; 陈艾

    2001-01-01

    The basic theory of the extension of cut-off wavelength of PtSi infrared detectors is discussed.Three methods are introduced including Tl+ and Ir+ doping, MBE growth of P+layer and B+, In+ low-energy ion-implantation.%讨论了将PtSi红外探测器截止波长延长的理论基础,并介绍了采用在衬底掺入Tl+和Ir+,MBE生长P+层以及低能离子注入B+,In+来延长PtSi红外探测器截止波长的三种方法。

  15. Deforming super Riemann surfaces with gravitinos and super Schottky groups

    Energy Technology Data Exchange (ETDEWEB)

    Playle, Sam [Dipartimento di Fisica, Università di Torino and INFN, Sezione di Torino,Via P. Giuria 1, I-10125 Torino (Italy)

    2016-12-12

    The (super) Schottky uniformization of compact (super) Riemann surfaces is briefly reviewed. Deformations of super Riemann surface by gravitinos and Beltrami parameters are recast in terms of super Schottky group cohomology. It is checked that the super Schottky group formula for the period matrix of a non-split surface matches its expression in terms of a gravitino and Beltrami parameter on a split surface. The relationship between (super) Schottky groups and the construction of surfaces by gluing pairs of punctures is discussed in an appendix.

  16. Dual-Functional On-Chip AlGaAs/GaAs Schottky Diode for RF Power Detection and Low-Power Rectenna Applications

    Directory of Open Access Journals (Sweden)

    Abdul Manaf Hashim

    2011-08-01

    Full Text Available A Schottky diode has been designed and fabricated on an n-AlGaAs/GaAs high-electron-mobility-transistor (HEMT structure. Current-voltage (I-V measurements show good device rectification, with a Schottky barrier height of 0.4349 eV for Ni/Au metallization. The differences between the Schottky barrier height and the theoretical value (1.443 eV are due to the fabrication process and smaller contact area. The RF signals up to 1 GHz are rectified well by the fabricated Schottky diode and a stable DC output voltage is obtained. The increment ratio of output voltage vs input power is 0.2 V/dBm for all tested frequencies, which is considered good enough for RF power detection. Power conversion efficiency up to 50% is obtained at frequency of 1 GHz and input power of 20 dBm with series connection between diode and load, which also shows the device’s good potential as a rectenna device with further improvement. The fabricated n-AlGaAs/GaAs Schottky diode thus provides a conduit for breakthrough designs for RF power detectors, as well as ultra-low power on-chip rectenna device technology to be integrated in nanosystems.

  17. Nondestructive imaging of buried interfaces in SiC and GaN Schottky contacts using scanning internal photoemission microscopy

    Science.gov (United States)

    Shiojima, Kenji; Yamamoto, Shingo; Kihara, Yuhei; Mishima, Tomoyoshi

    2015-04-01

    We demonstrate a nondestructive characterization of buried interfaces in metal/wide-bandgap semiconductor contacts by using scanning internal photoemission microscopy. For Ni/n-SiC contacts annealed at temperatures above 400 °C, a reduction of the Schottky barrier height owing to partial interfacial reaction was visualized. In Au/Ni/n-GaN contacts, upon annealing at 400 °C, thermal degradation from a scratch on the dot was observed. Forward current-voltage curves were reproduced by lowering the Schottky barrier height and the area of the reacted regions by using this method. The present imaging method exploits its nondestructive highly sensitive extinction for characterizing the contacts formed on wide-gap materials.

  18. 6H-SiC Schottky diode edge terminated using amorphous SiC by sputtering method

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, K.; Chen, Y.; Kuzmik, J.; Nishino, S. [Kyoto Inst. of Tech. (Japan). Dept. of Electronics and Information Science

    1998-08-01

    In this paper, we describe the experimental methods and the results on the evaluation of the Schottky barrier which is formed by vacuum-evaporation aluminum on chemically etched n-type 6H-SiC. And we report the effects of edge termination of amorphous SiC using reactive ion etching (RIE) and sputtering method. Edge termination was done by amorphous SiC in the trench etched by RIE using CF4 and O2. Amorphous SiC was formed by sputtering poly-SiC. Schottky barrier diodes have higher breakdown voltage at 300 V and lower leakage current than those without the edge termination. (orig.) 4 refs.

  19. Fabrication and Characterization of Al/p-CuInAlSe2 Thin Film Schottky Diodes

    Directory of Open Access Journals (Sweden)

    Usha Parihar

    2013-05-01

    Full Text Available Al/p-CuInAlSe2 polycrystalline schottky diodes fabricated by flash evaporation method were undertaken for their electrical analysis at room temperature. Diode parameters of the undertaken diodes were then derived from the current-voltage (I-V as well as capacitance-voltage (C-V characteristics. It has been observed that the schottky barrier height deduced from the room temperature I-V is lower to that obtained from the C-V characteristics and is attributed to the fact that I-V analysis includes both the image force and dipole lowering effects and is also reduced by the tunneling and leakage currents. The slope variation of the frequency dependent C – 2-V characteristics for the Al/p-CuInAlSe2 Schottky diode at varying frequency values from 50 kHz to 1 MHz suggests a large density of slow traps or interface states at the M-S junction. As emerging from the parameters values energy band diagram of Al and P-CuInAlSe2 has been reconstructed.

  20. Interdigitated Pt-GaN Schottky interfaces for high-temperature soot-particulate sensing

    Science.gov (United States)

    So, Hongyun; Hou, Minmin; Jain, Sambhav R.; Lim, Jongwoo; Senesky, Debbie G.

    2016-04-01

    A microscale soot-particulate sensor using interdigitated platinum-gallium nitride (Pt-GaN) Schottky interfaces was developed to monitor fine soot particles within high-temperature environments (e.g., combustion exhausts and flues). Upon exposure to soot particles (30 to 50 nm in diameter) from an experimental chimney, an increased current (∼43.6%) is observed through the back-to-back Schottky contact to n-type GaN. This is attributed to a reduction in the effective Schottky barrier height (SBH) of ∼10 meV due to the electric field from the charged soot particles in the depletion region and exposed GaN surface. Furthermore, the microfabricated sensor was shown to recover sensitivity and regenerate the sensing response (∼11 meV SBH reduction) after exposure to temperature as high as 550 °C. This study supports the feasibility of a simple and reliable soot sensor to meet the increasing market demand for particulate matter sensing in harsh environments.

  1. The electrical characterization and response to hydrogen of Schottky diodes with a resistive metal electrode-rectifying an oversight in Schottky diode investigation

    Energy Technology Data Exchange (ETDEWEB)

    Dawson, P; Feng, L; Penate-Quesada, L [Centre for Nanostructured Media, School of Maths and Physics, Queen' s University of Belfast, Belfast BT7 1NN (United Kingdom); Hill, G [EPSRC National Centre for III-V Technologies, Mappin Street, University ofSheffield, Sheffield S1 3JD (United Kingdom); Mitra, J, E-mail: P.dawson@qub.ac.uk

    2011-03-30

    Schottky-barrier structures with a resistive metal electrode are examined using the 4-point probe method where the probes are connected to the metal electrode only. The observation of a significant decrease in resistance with increasing temperature (over a range of {approx}100 K) in the diode resistance-temperature (R{sub D}-T) characteristic is considered due to charge carrier confinement to the metal electrode at low temperature (high resistance), with the semiconductor progressively opening up as a parallel current carrying channel (low resistance) with increasing temperature due to increasing thermionic emission across the barrier. A simple model is constructed, based on thermionic emission at quasi-zero bias, that generates good fits to the experimental data. The negative differential resistance (NDR) region in the R{sub D}-T characteristic is a general effect and is demonstrated across a broad temperature range for a variety of Schottky structures grown on Si-, GaAs- and InP-substrates. In addition the NDR effect is harnessed in micro-scaled Pd/n-InP devices for the detection of low levels of hydrogen in an ambient atmosphere of nitrogen.

  2. Electrical properties of silver Schottky contacts to ZnO thin films

    Institute of Scientific and Technical Information of China (English)

    LI Xin-kun; LI Qing-shan; LIANG De-chun; XU Yan-dong

    2009-01-01

    ZnO thin films are deposited on Al/Si substrates by the pulsed laser deposition (PLD) method. The XRD and SEM images of films are examined. Highly c-axis oriented ZnO thin films which have uniform compact surface morphology are fabricated. The size of surface grains is about 30 nm. The Schottky barrier ultraviolet detectors with silver Schottky contacts are made on ZnO thin films. The current-voltage characteristics are measured. The ideality contact factor between Ag and ZnO film is 1.22, while the barrier height is 0.908 e V. After annealing at 600 ℃ for 2h, the ideafity factor is 1.18 and the barrier height is 0.988 eV. With the illumination of 325 nm wavelength UV-light, the photocurrent-to-dark current ratios before and after annealing are 140.4 and 138.4 biased at 5 V, respectively. The photocurrents increase more than two orders of magnitude over the dark currents.

  3. Limitations in THz Power Generation with Schottky Diode Varactor Frequency Multipliers

    DEFF Research Database (Denmark)

    Krozer, Viktor; Loata, G.; Grajal, J.

    2002-01-01

    We discuss the limitations in power generation with Schottky diode and HBV (heterostructure barrier varactor) diode frequency multipliers. It is shown that at lower frequencies the experimental results achieved so far approach the theoretical limit of operation for the employed devices. However......, at increasing frequencies the power drops with f-3 instead of the f-2 predicted by theory. In this contribution we provide an overview of state-of-the-art results. A comparison with theoretically achievable multiplier performance reveals that the devices employed at higher frequencies are operating...

  4. Diameter-dependent electronic transport properties of Au-catalyst/Ge-nanowire Schottky diodes

    Energy Technology Data Exchange (ETDEWEB)

    Picraux, S Thomas [Los Alamos National Laboratory; Leonard, Francois [SNL; Swartzentruber, Brian S [SNL; Talin, A Alee [SNL

    2008-01-01

    We present electronic transport measurements in individual Au-catalyst/Ge-nanowire interfaces demonstrating the presence of a Schottky barrier. Surprisingly, the small-bias conductance density increases with decreasing diameter. Theoretical calculations suggest that this effect arises because electron-hole recombination in the depletion region is the dominant charge transport mechanism, with a diameter dependence of both the depletion width and the electron-hole recombination time. The recombination time is dominated by surface contributions and depends linearly on the nanowire diameter.

  5. Effects of thermal annealing on Cu/6H-SiC Schottky properties

    Energy Technology Data Exchange (ETDEWEB)

    Hatayama, T.; Suezaki, T.; Kawahito, K.; Uraoka, Y.; Fuyuki, T. [Nara Inst. of Science and Technology, Ikoma (Japan). Graduate School of Materials Science

    2001-07-01

    Effects of thermal annealing for copper (Cu) contacts on 6H-SiC (0001) Si-face were analyzed in detail. Cu/6H-SiC structures had good Schottky electrical properties with the ideality factor below 1.1 even after thermal annealing at 500 C. The barrier height of 1.22 V for an as-deposited Cu contact increased to 1.45 V after annealing at 500 C. However, electrical properties were deteriorated after annealing over 500 C, which is caused by the formation of copper silicides at the Cu/6H-SiC interface. (orig.)

  6. Influence of illumination intensity on the electrical characteristics and photoresponsivity of the Ag/ZnO Schottky diodes

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, RuiJuan; Zhang, XinAn, E-mail: xinanzhang@henu.edu.cn; Zhao, JunWei; Li, RuoPing; Zhang, WeiFeng

    2015-05-15

    Highlights: • Ag/ZnO Schottky diodes were fabricated. • The electrical parameters of the diodes were obtained and analyzed. • The electrical properties under UV illuminations were discussed. - Abstract: In this article, the ZnO thin films were grown by RF-magnetron sputtering on ITO glass substrates. The Schottky diodes with the configuration of Ag/ZnO/ITO have been fabricated and it has been observed that the diodes exhibit a good rectification. The structural and optical properties of the ZnO films were investigated by X-ray diffractometry and spectrophotometry. The current–voltage (I–V) characteristics of the Ag/ZnO diode were measured under various illuminations. We use the forward bias current–voltage measurements to determine the electrical parameters such as ideality factor, barrier height and series resistance of the diode. The Ag/ZnO Schottky diode exhibits a non-ideal behavior due to the interfacial layer, the interface states and the series resistance. It is found that the barrier height and ideality factor values are strong functions of illumination intensity. The results show that the ideality factor and the barrier height decrease with increasing illumination intensity. The values of R{sub s} obtained from Cheung and Norde methods are decreased with increasing illumination intensity. Photoresponse characteristics of the diode have been analyzed and it is clear that the diode shows a fast response. It is evaluated that the prepared diodes can be used as optoelectronic devices.

  7. Vertical semiconducting single-walled carbon nanotube Schottky diode

    Science.gov (United States)

    Jung, Sunghwan

    2014-07-01

    This paper presents a vertical semiconducting single-walled carbon nanotube (sSWCNT)-based Schottky device. For the first time, the author successfully demonstrated a vertical s-SWCNT Schottky diode on an anodized aluminum oxide (AAO) template. In the vertical pores of an AAO template s-SWCNTs were vertically grown and aligned. The vertical growth of s-SWCNTs inside the pores was achieved by successfully isolating the catalyst at the bottom of the pores by using redeposition enabled angled ion milling. The ends of the grown s-SWCNTs were coated with palladium and titanium to form Schottky and Ohmic contacts, respectively. The I-V characteristics of the vertical s-SWCNT paths engaging the Schottky and Ohmic contacts well demonstrated Schottky diode rectification.

  8. Thermionic field emission in gold nitride Schottky nanodiodes

    Science.gov (United States)

    Spyropoulos-Antonakakis, N.; Sarantopoulou, E.; Kollia, Z.; Samardžija, Z.; Kobe, S.; Cefalas, A. C.

    2012-11-01

    We report on the thermionic field emission and charge transport properties of gold nitride nanodomains grown by pulsed laser deposition with a molecular fluorine laser at 157 nm. The nanodomains are sandwiched between the metallic tip of a conductive atomic force microscope and a thin gold layer forming thus a metal-semiconductor-metal junction. Although the limited existing data in the literature indicate that gold nitride was synthesized previously with low efficiency, poor stability, and metallic character; in this work, it is shown that gold nitride nanodomains exhibit semiconducting behavior and the metal-semiconductor-metal contact can be modeled with the back-to-back Schottky barrier model. From the experimental I-V curves, the main charge carrier transport process is found to be thermionic field emission via electron tunneling. The rectifying, near symmetric and asymmetric current response of nanocontacts is related to the effective contact area of the gold nitride nanodomains with the metals. A lower limit for the majority charge carriers concentration at the boundaries of nanodomains is also established using the full depletion approximation, as nanodomains with thickness as low as 6 nm were found to be conductive. Current rectification and charge memory effects are also observed in "quite small" conductive nanodomains (6-10 nm) due to stored charges. Indeed, charges near the surface are identified as inversion domains in the phase shift mapping performed with electrostatic force microscopy and are attributed to charge trapping at the boundaries of the nanodomains.

  9. Catalytic-Metal/PdO(sub x)/SiC Schottky-Diode Gas Sensors

    Science.gov (United States)

    Hunter, Gary W.; Xu, Jennifer C.; Lukco, Dorothy

    2006-01-01

    Miniaturized hydrogen- and hydrocarbon-gas sensors, heretofore often consisting of Schottky diodes based on catalytic metal in contact with SiC, can be improved by incorporating palladium oxide (PdOx, where 0 less than or equal to x less than or equal to 1) between the catalytic metal and the SiC. In prior such sensors in which the catalytic metal was the alloy PdCr, diffusion and the consequent formation of oxides and silicides of Pd and Cr during operation at high temperature were observed to cause loss of sensitivity. However, it was also observed that any PdOx layers that formed and remained at PdCr/SiC interfaces acted as barriers to diffusion, preventing further deterioration by preventing the subsequent formation of metal silicides. In the present improvement, the lesson learned from these observations is applied by placing PdOx at the catalytic metal/SiC interfaces in a controlled and uniform manner to form stable diffusion barriers that prevent formation of metal silicides. A major advantage of PdOx over other candidate diffusion-barrier materials is that PdOx is a highly stable oxide that can be incorporated into gas sensor structures by use of deposition techniques that are standard in the semiconductor industry. The PdOx layer can be used in a gas sensor structure for improved sensor stability, while maintaining sensitivity. For example, in proof-of-concept experiments, Pt/PdOx/SiC Schottky-diode gas sensors were fabricated and tested. The fabrication process included controlled sputter deposition of PdOx to a thickness of 50 Angstroms on a 400-m-thick SiC substrate, followed by deposition of Pt to a thickness of 450 Angstroms on the PdOx. The SiC substrate (400 microns in thickness) was patterned with photoresist and a Schottky-diode photomask. A lift-off process completed the definition of the Schottky-diode pattern. The sensors were tested by measuring changes in forward currents at a bias potential of 1 V during exposure to H2 in N2 at temperatures

  10. Transport properties in a monolayer graphene modulated by the realistic magnetic field and the Schottky metal stripe

    Science.gov (United States)

    Lu, Jian-Duo; Li, Yun-Bao; Liu, Hong-Yu; Peng, Shun-Jin; Zhao, Fei-Xiang

    2016-09-01

    Based on the transfer-matrix method, a systematic investigation of electron transport properties is done in a monolayer graphene modulated by the realistic magnetic field and the Schottky metal stripe. The strong dependence of the electron transmission and the conductance on the incident angle of carriers is clearly seen. The height, position as well as width of the barrier also play an important role on the electron transport properties. These interesting results are very useful for understanding the tunneling mechanism in the monolayer graphene and helpful for designing the graphene-based electrical device modulated by the realistic magnetic field and the electrical barrier.

  11. Numerical simulations of the electrical transport characteristics of a Pt/n-GaN Schottky diode

    Science.gov (United States)

    Bouzid, Fayçal; Pezzimenti, Fortunato; Dehimi, Lakhdar; Megherbi, Mohamed L.; Della Corte, Francesco G.

    2017-09-01

    In this paper, using a numerical simulator, we investigated the current-voltage characteristics of a Pt/n-GaN thin Schottky diode on the basis of the thermionic emission (TE) theory in the 300 to 500 K temperature range. During the simulations, the effect of different defect states within the n-GaN bulk with different densities and spatial locations is considered. The results show that the diode ideality factor and the threshold voltage decrease with increasing temperature, while at the same time, the zero-bias Schottky barrier height (Φb0) extracted from the forward current density-voltage (J-V) characteristics increases. The observed behaviors of the ideality factor and zero-bias barrier height are analyzed on the basis of spatial barrier height inhomogeneities at the Pt/GaN interface by assuming a Gaussian distribution (GD). The plot of apparent barrier height (Φb,App) as a function of q/2kT gives a straight line, where the mean zero-bias barrier height (\\overline{Φ \\text{b0}}) and the standard deviation (σ0) are 1.48 eV and 0.047 V, respectively. The plot of the modified activation energy against q/kT gives an almost the same value of \\overline{Φ \\text{b0}} and an effective Richardson constant A* of 28.22 A cm-2 K-2, which is very close to the theoretical value for n-type GaN/Pt contacts. As expected, the presence of defect states with different trap energy levels has a noticeable impact on the device electrical characteristics.

  12. Electrical and structural properties of (Pd/Au) Schottky contact to as grown and rapid thermally annealed GaN grown by MBE

    Energy Technology Data Exchange (ETDEWEB)

    Nirwal, Varun Singh, E-mail: varun.nirwal30@gmail.com; Singh, Joginder; Gautam, Khyati; Peta, Koteswara Rao [Department of Electronic Science, University of Delhi South Campus, Benito Juarez Road, New Delhi-110021 (India)

    2016-05-06

    We studied effect of thermally annealed GaN surface on the electrical and structural properties of (Pd/Au) Schottky contact to Ga-polar GaN grown by molecular beam epitaxy on Si substrate. Current voltage (I-V) measurement was used to study electrical properties while X-ray diffraction (XRD) measurement was used to study structural properties. The Schottky barrier height calculated using I-V characteristics was 0.59 eV for (Pd/Au) Schottky contact on as grown GaN, which increased to 0.73 eV for the Schottky contact fabricated on 700 °C annealed GaN film. The reverse bias leakage current at -1 V was also significantly reduced from 6.42×10{sup −5} A to 7.31×10{sup −7} A after annealing. The value of series resistance (Rs) was extracted from Cheung method and the value of R{sub s} decreased from 373 Ω to 172 Ω after annealing. XRD results revealed the formation of gallide phases at the interface of (Pd/Au) and GaN for annealed sample, which could be the reason for improvement in the electrical properties of Schottky contact after annealing.

  13. Improved surface plasmon enhanced photodetection at an Au-GaAs Schottky junction using a novel molecular beam epitaxy grown Otto coupling structure

    Energy Technology Data Exchange (ETDEWEB)

    Daboo, C.; Baird, M.J.; Hughes, H.P. (PCS Group, Cavendish Lab., Cambridge (UK)); Apsley, N.; Emeny, M.T. (Royal Signals and Radar Establishment, Great Malvern (UK))

    1991-06-05

    Measurements of reflectivity and photocurrent as a function of angle of incidence and wavelength have been made for a GaAs-AlAs-GaAs-Au Schottky structure based on an Otto coupling geometry which allows incident p-polarized radiation to couple to the surface plasmon (SP) mode at the Au-GaAs interface. At resonance, E fields associated with the SP excitation are concentrated at the GaAs-Au Schottky interface itself, enabling strong enhancement of the internal photoemission photocurrent across the Schottky barrier. Enhancement factors of the order of 20 have been achieved. A direct comparison between the resonant effects of exciting the SP at the GaAs-Au Schottky junction itself and at the outer Au-air interface has been made. A simple model for the photocurrent in the device indicates that the excited photocarriers created in the gold film have a very short scattering length {delta}{approx equal}10 nm, which emphasizes the importance of exciting the SP at the Schottky interface. (orig.).

  14. Temperature dependence of current-and capacitance-voltage characteristics of an Au/4H-SiC Schottky diode

    Science.gov (United States)

    Gülnahar, Murat

    2014-12-01

    In this study, the current-voltage (I-V) and capacitance-voltage (C-V) measurements of an Au/4H-SiC Schottky diode are characterized as a function of the temperature in 50-300 K temperature range. The experimental parameters such as ideality factor and apparent barrier height presents to be strongly temperature dependent, that is, the ideality factor increases and the apparent barrier height decreases with decreasing temperature, whereas the barrier height values increase with the temperature for C-V data. Likewise, the Richardson plot deviates at low temperatures. These anomaly behaviors observed for Au/4H-SiC are attributed to Schottky barrier inhomogeneities. The barrier anomaly which relates to interface of Au/4H-SiC is also confirmed by the C-V measurements versus the frequency measured in 300 K and it is interpreted by both Tung's lateral inhomogeneity model and multi-Gaussian distribution approach. The values of the weighting coefficients, standard deviations and mean barrier height are calculated for each distribution region of Au/4H-SiC using the multi-Gaussian distribution approach. In addition, the total effective area of the patches NAe is obtained at separate temperatures and as a result, it is expressed that the low barrier regions influence meaningfully to the current transport at the junction. The homogeneous barrier height value is calculated from the correlation between the ideality factor and barrier height and it is noted that the values of standard deviation from ideality factor versus q/3kT curve are in close agreement with the values obtained from the barrier height versus q/2kT variation. As a result, it can be concluded that the temperature dependent electrical characteristics of Au/4H-SiC can be successfully commented on the basis of the thermionic emission theory with both models.

  15. New type of Schottky diode-based Cu-Al-Mn-Cr shape memory material films

    Science.gov (United States)

    Aksu Canbay, C.; Dere, A.; Mensah-Darkwa, Kwadwo; Al-Ghamdi, Ahmed; Karagoz Genç, Z.; Gupta, R. K.; Yakuphanoglu, F.

    2016-07-01

    Cr-doped CuAlMn shape memory alloys were produced by arc melting method. The effects of Cr content on microstructure and transformation parameters of were investigated. The alloys were characterized by X-ray analysis, optical microscope observations and differential scanning calorimetry measurements. The grain size of the alloys was decreased by the addition of Cr into CuAlMn alloy system. The martensite transformation temperature was shifted both the lower temperature and higher temperature with the addition of chromium. This change was explained on the basis of the change in the thermodynamics such as enthalpy, entropy and activation energy values. The obtained results indicate that the phase transformation temperatures of the CuAlMn alloy system can be controlled by addition of Cr. We fabricated a Schottky barrier diode and observed that ideality factor and barrier height increase with increasing temperature. The diodes exhibited a thermal sensor behavior. This indicates that Schottky diode-based Cu-Al-Mn-Cr shape memory material films can be used as a sensor in high-temperature measurement applications.

  16. Double threshold behaviour of I-V characteristics of CoSi2/Si Schottky contacts

    Institute of Scientific and Technical Information of China (English)

    Zhu Shi-Yang(竺士炀); Ru Guo-Ping(茹国平); Qu Xin-Ping(屈新萍); Li Bing-Zong(李炳宗); R.L.Van Meirhaeghe; C.Detavernier; F.Cardon

    2002-01-01

    The forward current-voltage (I-V) characteristics of polycrystalline CoSi2/n-Si(100) Schottky contacts have beenmeasured in a wide temperature range. At low temperatures (≤200K), a plateau-like section is observed in the I-Vmodel based on thermionic emission (TE) and a Gaussian distribution of Schottky barrier height (SBH). Such a doublethreshold behaviour can be explained by the barrier height inhomogeneity, i.e. at low temperatures the current throughpatches with low SBH dominates at small bias region With increasing bias voltage, the Ohmic effect becomes someimportant and the current through the whole junction area exc eeds the patch current, thus resulting in a plateau-likesection in the I-V curves at moderate bias. For the polycrystalline CoSi2/Si contacts studied in this paper, the apparentideality factor of the patch current is much larger than that calculated from the TE model taking the pinch-off effectinto account. This suggests that the current flowing through these patches is of the tunnelling type, rather than thethermionic emission type. The experimental I-V characteristics can be fitted reasonably well in the whole temperatureregion using the model based on tunnelling and pinch-off.

  17. Monolayer graphene film on ZnO nanorod array for high-performance Schottky junction ultraviolet photodetectors.

    Science.gov (United States)

    Nie, Biao; Hu, Ji-Gang; Luo, Lin-Bao; Xie, Chao; Zeng, Long-Hui; Lv, Peng; Li, Fang-Ze; Jie, Jian-Sheng; Feng, Mei; Wu, Chun-Yan; Yu, Yong-Qiang; Yu, Shu-Hong

    2013-09-09

    A new Schottky junction ultraviolet photodetector (UVPD) is fabricated by coating a free-standing ZnO nanorod (ZnONR) array with a layer of transparent monolayer graphene (MLG) film. The single-crystalline [0001]-oriented ZnONR array has a length of about 8-11 μm, and a diameter of 100∼600 nm. Finite element method (FEM) simulation results show that this novel nanostructure array/MLG heterojunction can trap UV photons effectively within the ZnONRs. By studying the I-V characteristics in the temperature range of 80-300 K, the barrier heights of the MLG film/ZnONR array Schottky barrier are estimated at different temperatures. Interestingly, the heterojunction diode with typical rectifying characteristics exhibits a high sensitivity to UV light illumination and a quick response of millisecond rise time/fall times with excellent reproducibility, whereas it is weakly sensitive to visible light irradiation. It is also observed that this UV photodetector (PD) is capable of monitoring a fast switching light with a frequency as high as 2250 Hz. The generality of the above results suggest that this MLG film/ZnONR array Schottky junction UVPD will have potential application in future optoelectronic devices.

  18. Humidity influenced capacitance and resistance of an Al/DNA/Al Schottky diode irradiated by alpha particles

    Science.gov (United States)

    Al-Ta'Ii, Hassan Maktuff Jaber; Amin, Yusoff Mohd; Periasamy, Vengadesh

    2016-05-01

    Deoxyribonucleic acid or DNA based sensors, especially as humidity and alpha particle sensors have become quite popular in recent times due to flexible and highly optimizable nature of this fundamental biomaterial. Application of DNA electronics allow for more sensitive, accurate and effective sensors to be developed and fabricated. In this work, we examined the effect of different humidity conditions on the capacitive and resistive response of Aluminum (Al)/DNA/Al Schottky barrier structure when bombarded by time-dependent dosages of alpha particles. Based on current-voltage profiles, which demonstrated rectifying behaviours, Schottky diode parameters such as ideality factor, barrier height and series resistance was calculated. Results observed generally pointed towards a decrease in the resistance value from the pristine to the radiated structures. It was also demonstrated that under the effect of humidity, the capacitance of the DNA thin film increased from 0.05894 to 92.736 nF, with rising relative humidity level. We also observed the occurrence of the hypersensitivity phenomena after alpha irradiation between 2 to 4 min by observing a drop in the series resistance, crucial in the study of DNA damage and repair mechanisms. These observations may also suggest the exciting possibility of utilizing Al/DNA/Al Schottky diodes as potentially sensitive humidity sensors.

  19. Au nanoparticles embedded at the interface of Al/4H-SiC Schottky contacts for current density enhancement

    Science.gov (United States)

    Gorji, Mohammad Saleh; Cheong, Kuan Yew

    2015-01-01

    Nanostructured contacts, comprised of nanoparticles (NPs) embedded at the interface of contact/semiconductor, offer a viable solution in modification of Schottky barrier height (SBH) in Schottky contacts. The successful performance of devices with such nanostructured contacts requires a feasible selection of NPs/contact material based on theoretical calculations and a cost effective and reproducible route for NPs deposition. Acidification of commercially available colloidal Au NPs solution by HF has been selected here as a simple bench-top technique for deposition of Au NPs on n- and p-type 4H-SiC substrates. Theoretical calculations based on the model of inhomogeneity in SBH (ISBH) were used to make a more appropriate selection of NPs type (Au) and size (5 and 10 nm, diameter) with respect to contact metal (Al). Al/Au NPs/SiC Schottky barrier diodes were then fabricated, and their electrical characteristics exhibited current density enhancement due to the SBH lowering. The source of SBH lowering was determined to be the local electric field enhancement due to NPs effect, which was further investigated using the models of ISBH and tunneling enhancement at triple interface.

  20. Tracking the Effect of Adatom Electronegativity on Systematically Modified AlGaN/GaN Schottky Interfaces.

    Science.gov (United States)

    Reiner, Maria; Pietschnig, Rudolf; Ostermaier, Clemens

    2015-10-21

    The influence of surface modifications on the Schottky barrier height for gallium nitride semiconductor devices is frequently underestimated or neglected in investigations thereof. We show that a strong dependency of Schottky barrier heights for nickel/aluminum-gallium nitride (0001) contacts on the surface terminations exists: a linear correlation of increasing barrier height with increasing electronegativity of superficial adatoms is observed. The negatively charged adatoms compete with the present nitrogen over the available gallium (or aluminum) orbital to form an electrically improved surface termination. The resulting modification of the surface dipoles and hence polarization of the surface termination causes observed band bending. Our findings suggest that the greatest Schottky barrier heights are achieved by increasing the concentration of the most polarized fluorine-gallium (-aluminum) bonds at the surface. An increase in barrier height from 0.7 to 1.1 eV after a 15% fluorine termination is obtained with ideality factors of 1.10 ± 0.05. The presence of surface dipoles that are changing the surface energy is proven by the sessile drop method as the electronegativity difference and polarization influences the contact angle. The extracted decrease in the Lifshitz-van-der-Waals component from 48.8 to 40.4 mJ/m(2) with increasing electronegativity and concentration of surface adatoms confirms the presence of increasing surface dipoles: as the polarizability of equally charged anions decreases with increasing electronegativity, the diiodomethane contact angles increase significantly from 14° up to 39° after the 15% fluorine termination. Therefore, a linear correlation between increasing anion electronegativity of the (Al)GaN termination and total surface energy within a 95% confidence interval is obtained. Furthermore, our results reveal a generally strong Lewis basicity of (Al)GaN surfaces explaining the high chemical inertness of the surfaces.

  1. Using Atom-Probe Tomography to Understand Zn O ∶Al /SiO 2/Si Schottky Diodes

    Science.gov (United States)

    Jaramillo, R.; Youssef, Amanda; Akey, Austin; Schoofs, Frank; Ramanathan, Shriram; Buonassisi, Tonio

    2016-09-01

    We use electronic transport and atom-probe tomography to study Zn O ∶Al /SiO 2/Si Schottky diodes on lightly doped n - and p -type Si. We vary the carrier concentration in the ZnO ∶Al films by 2 orders of magnitude, but the Schottky barrier height remains nearly constant. Atom-probe tomography shows that Al segregates to the interface, so that the ZnO ∶Al at the junction is likely to be metallic even when the bulk of the ZnO ∶Al film is semiconducting. We hypothesize that the observed Fermi-level pinning is connected to the insulator-metal transition in doped ZnO. This implies that tuning the band alignment at oxide/Si interfaces may be achieved by controlling the transition between localized and extended states in the oxide, thereby changing the orbital hybridization across the interface.

  2. Destructive Single-Event Failures in Schottky Diodes

    Science.gov (United States)

    Casey, Megan C.; Lauenstein, Jean-Marie; Gigliuto, Robert A.; Wilcox, Edward P.; Phan, Anthony M.; Kim, Hak; Chen, Dakai; LaBel, Kenneth A.

    2014-01-01

    This presentation contains test results for destructive failures in DC-DC converters. We have shown that Schottky diodes are susceptible to destructive single-event effects. Future work will be completed to identify parameter that determines diode susceptibility.

  3. Study of Reduced Graphene Oxide for Trench Schottky Diode

    Science.gov (United States)

    Samihah Khairir, Nur; Rofei Mat Hussin, Mohd; Nasir, Iskhandar Md; Mukhter Uz-Zaman, A. S. M.; Fazlida Hanim Abdullah, Wan; Sabirin Zoolfakar, Ahmad

    2015-11-01

    This paper presents the study of reduced Graphene Oxide (RGO) for trench Schottky diode by replacing conventional metal layer that forms schottky contact with a nanostructured carbon thin film via Reduced Graphene Oxide (RGO) technique. The RGO was synthesis by chemical exfoliation in which modified Hummer's method was approached. It was then deposited on the trench schottky pattern substrate by pressurized spray coating. The sample was then characterized by FESEM, Raman Spectroscopy and I-V test. The results of FESEM and Raman showed good characteristics and well deposited nanostructures of RGO flakes. The two-point I-V test showed that the samples have a low turn-on voltage and a higher break-down voltage, which is better than the conventional schottky diode used in the market.

  4. Failure Analysis of Heavy-Ion-Irradiated Schottky Diodes

    Science.gov (United States)

    Casey, Megan C.; Lauenstein, Jean-Marie; Wilcox, Edward P.; Topper, Alyson D.; Campola, Michael J.; Label, Kenneth A.

    2017-01-01

    In this work, we use high- and low-magnitude optical microscope images, infrared camera images, and scanning electron microscope images to identify and describe the failure locations in heavy-ion-irradiated Schottky diodes.

  5. Summary of LHC MD:377: Schottky pick-up

    CERN Document Server

    Betz, Michael; Lefevre, Thibaut; CERN. Geneva. ATS Department

    2015-01-01

    The main objective of this MD was to record Schottky spectra under well known machine conditions. In summary, 7 set-points for the chromaticity and 8 for the emittance have been established and Schottky spectra have been recorded for each setting. The data will be used to benchmark and develop different fitting algorithms. This note presents the initial attempt of curve-fitting and discusses its shortcomings.

  6. Temperature dependent electrical characterisation of Pt/HfO{sub 2}/n-GaN metal-insulator-semiconductor (MIS) Schottky diodes

    Energy Technology Data Exchange (ETDEWEB)

    Shetty, Arjun, E-mail: arjun@ece.iisc.ernet.in; Vinoy, K. J. [Electrical Communication Engineering, Indian Institute of Science, Bangalore, India 560012 (India); Roul, Basanta; Mukundan, Shruti; Mohan, Lokesh; Chandan, Greeshma; Krupanidhi, S. B. [Materials Research Centre, Indian Institute of Science, Bangalore, India 560012 (India)

    2015-09-15

    This paper reports an improvement in Pt/n-GaN metal-semiconductor (MS) Schottky diode characteristics by the introduction of a layer of HfO{sub 2} (5 nm) between the metal and semiconductor interface. The resulting Pt/HfO{sub 2}/n-GaN metal-insulator-semiconductor (MIS) Schottky diode showed an increase in rectification ratio from 35.9 to 98.9(@ 2V), increase in barrier height (0.52 eV to 0.63eV) and a reduction in ideality factor (2.1 to 1.3) as compared to the MS Schottky. Epitaxial n-type GaN films of thickness 300nm were grown using plasma assisted molecular beam epitaxy (PAMBE). The crystalline and optical qualities of the films were confirmed using high resolution X-ray diffraction and photoluminescence measurements. Metal-semiconductor (Pt/n-GaN) and metal-insulator-semiconductor (Pt/HfO{sub 2}/n-GaN) Schottky diodes were fabricated. To gain further understanding of the Pt/HfO{sub 2}/GaN interface, I-V characterisation was carried out on the MIS Schottky diode over a temperature range of 150 K to 370 K. The barrier height was found to increase (0.3 eV to 0.79 eV) and the ideality factor decreased (3.6 to 1.2) with increase in temperature from 150 K to 370 K. This temperature dependence was attributed to the inhomogeneous nature of the contact and the explanation was validated by fitting the experimental data into a Gaussian distribution of barrier heights.

  7. Characterization of AlGaN-based metal-semiconductor solar-blind UV photodiodes with IrO{sub 2} Schottky contacts

    Energy Technology Data Exchange (ETDEWEB)

    Schalkwyk, L. van, E-mail: Louwrens.VanSchalkwyk@up.ac.za [Department of Physics, University of Pretoria, Private bag X20, Hatfield 0028 (South Africa); Meyer, W.E.; Auret, F.D.; Nel, J.M.; Ngoepe, P.N.M.; Diale, M. [Department of Physics, University of Pretoria, Private bag X20, Hatfield 0028 (South Africa)

    2012-05-15

    Intrinsically solar-blind ultraviolet (UV) AlGaN-based Schottky photodiodes were fabricated using Iridium oxide (IrO{sub 2}) as the Schottky barrier material. The Ir Schottky contacts were annealed at 700 Degree-Sign C under O{sub 2} ambient and the photodiodes characterized with an optoelectronic system. The main parameters extracted from I-V measurements were an average ideality factor of 1.38, a Schottky barrier height of 1.52 eV, a reverse leakage current density at -1 V bias of 5.2 nA/cm{sup 2} and series resistance of 250{Omega}. After spectral characterization, it was found that annealing, alone, of the Ir contact to form the more UV transmissive IrO{sub 2} does not always improve the responsivity. The deposition of a Au probe contact on the IrO{sub 2} contact increased the responsivity from 40 mA/W to 52 mA/W at 275 nm with respect to the annealed Ir contact. However, the ideality factor degraded to 1.57, Schottky barrier height lowered to 1.19 eV, reverse leakage current density increased to 49 nA/cm{sup 2} and series resistance decreased to 100{Omega} with the addition of the Au contact. The radiation hardness of AlGaN was also confirmed after studying the effects of 5.4 MeV He-ion irradiation using {sup 241}Am for a total fluence of 3 Multiplication-Sign 10{sup 13} cm{sup -2}.

  8. High Voltage GaN Schottky Rectifiers

    Energy Technology Data Exchange (ETDEWEB)

    CAO,X.A.; CHO,H.; CHU,S.N.G.; CHUO,C.-C.; CHYI,J.-I.; DANG,G.T.; HAN,JUNG; LEE,C.-M.; PEARTON,S.J.; REN,F.; WILSON,R.G.; ZHANG,A.P.

    1999-10-25

    Mesa and planar GaN Schottky diode rectifiers with reverse breakdown voltages (V{sub RB}) up to 550V and >2000V, respectively, have been fabricated. The on-state resistance, R{sub ON}, was 6m{Omega}{center_dot} cm{sup 2} and 0.8{Omega}cm{sup 2}, respectively, producing figure-of-merit values for (V{sub RB}){sup 2}/R{sub ON} in the range 5-48 MW{center_dot}cm{sup -2}. At low biases the reverse leakage current was proportional to the size of the rectifying contact perimeter, while at high biases the current was proportional to the area of this contact. These results suggest that at low reverse biases, the leakage is dominated by the surface component, while at higher biases the bulk component dominates. On-state voltages were 3.5V for the 550V diodes and {ge}15 for the 2kV diodes. Reverse recovery times were <0.2{micro}sec for devices switched from a forward current density of {approx}500A{center_dot}cm{sup -2} to a reverse bias of 100V.

  9. Schottky Heterodyne Receivers With Full Waveguide Bandwidth

    Science.gov (United States)

    Hesler, Jeffrey; Crowe, Thomas

    2011-01-01

    Compact THz receivers with broad bandwidth and low noise have been developed for the frequency range from 100 GHz to 1 THz. These receivers meet the requirements for high-resolution spectroscopic studies of planetary atmospheres (including the Earth s) from spacecraft, as well as airborne and balloon platforms. The ongoing research is significant not only for the development of Schottky mixers, but also for the creation of a receiver system, including the LO chain. The new receivers meet the goals of high sensitivity, compact size, low total power requirement, and operation across complete waveguide bands. The exceptional performance makes these receivers ideal for the broader range of scientific and commercial applications. These include the extension of sophisticated test and measurement equipment to 1 THz and the development of low-cost imaging systems for security applications and industrial process monitoring. As a particular example, a WR-1.9SHM (400-600 GHz) has been developed (see Figure 1), with state-of-the-art noise temperature ranging from 1,000-1,800 K (DSB) over the full waveguide band. Also, a Vector Network Analyzer extender has been developed (see Figure 2) for the WR1.5 waveguide band (500 750 GHz) with 100-dB dynamic range.

  10. Single Schottky junction FETs based on Si:P nanowires with axially graded doping

    Science.gov (United States)

    Barreda, Jorge; Keiper, Timothy; Zhang, Mei; Xiong, Peng

    2015-03-01

    Si nanowires (NWs) with a systematic axial increase in phosphorus doping have been synthesized via a vapor-liquid-solid method. Silane and phosphine precursor gases are utilized for the growth and doping, respectively. The phosphorous doping profile is controlled by the flow ratio of the precursor gases. After the as-grown product is ultrasonically agitated into a solution, the Si NWs are dispersed on a SiO2 substrate with a highly doped Si back gate. Individual NWs are identified for the fabrication of field-effect transistors (FETs) with multiple Cr/Ag contacts along the NW. Two-probe and four-probe measurements are taken systematically under vacuum conditions at room temperature and the contribution from each contact and each NW section between adjacent contacts is determined. The graded doping level, produced by a systematic reduction in dopant density along the length of the NWs, is manifested in the regular increases in the channel and contact resistances. Our Si NWs facilitate the fabrication of asymmetric FETs with one ohmic and one Schottky contact. A significant increase in gate modulation is obtained due to the single Schottky-barrier contact. Characterization details and the applicability for sensing purposes will be discussed.

  11. A sensitive ultraviolet light photodiode based on graphene-on-zinc oxide Schottky junction

    Directory of Open Access Journals (Sweden)

    Zhang Teng-Fei

    2016-11-01

    Full Text Available In this study, we present a simple ultraviolet (UV light photodiode by transferring a layer of graphene film on single-crystal ZnO substrate. The as-fabricated heterojunction exhibited typical rectifying behavior, with a Schottky barrier height of 0.623 eV. Further optoelectronic characterization revealed that the graphene-ZnO Schottky junction photodiode displayed obvious sensitivity to 365-nm light illumination with good reproducibility. The responsivity and photoconductive gain were estimated to be 3×104 A/W and 105, respectively, which were much higher than other ZnO nanostructure-based devices. In addition, it was found that the on/off ratio of the present device can be considerably improved from 2.09 to 12.1, when the device was passivated by a layer of AlOx film. These results suggest that the present simply structured graphene-ZnO UV photodiode may find potential application in future optoelectronic devices.

  12. X-ray detection with zinc-blende (cubic) GaN Schottky diodes.

    Science.gov (United States)

    Gohil, T; Whale, J; Lioliou, G; Novikov, S V; Foxon, C T; Kent, A J; Barnett, A M

    2016-01-01

    The room temperature X-ray responses as functions of time of two n type cubic GaN Schottky diodes (200 μm and 400 μm diameters) are reported. The current densities as functions of time for both diodes showed fast turn-on transients and increases in current density when illuminated with X-ray photons of energy up to 35 keV. The diodes were also electrically characterized: capacitance, implied depletion width and dark current measurements as functions of applied bias at room temperature are presented. At -5 V reverse bias, the capacitances of the diodes were measured to be (84.05 ± 0.01) pF and (121.67 ± 0.02) pF, respectively. At -5 V reverse bias, the dark current densities of the diodes were measured to be (347.2 ± 0.4) mA cm(-2) and (189.0 ± 0.2) mA cm(-2), respectively. The Schottky barrier heights of the devices (0.52 ± 0.07) eV and (0.63 ± 0.09) eV, respectively, were extracted from the forward dark current characteristics.

  13. Hot carrier multiplication on graphene/TiO2 Schottky nanodiodes

    Science.gov (United States)

    Lee, Young Keun; Choi, Hongkyw; Lee, Hyunsoo; Lee, Changhwan; Choi, Jin Sik; Choi, Choon-Gi; Hwang, Euyheon; Park, Jeong Young

    2016-06-01

    Carrier multiplication (i.e. generation of multiple electron–hole pairs from a single high-energy electron, CM) in graphene has been extensively studied both theoretically and experimentally, but direct application of hot carrier multiplication in graphene has not been reported. Here, taking advantage of efficient CM in graphene, we fabricated graphene/TiO2 Schottky nanodiodes and found CM-driven enhancement of quantum efficiency. The unusual photocurrent behavior was observed and directly compared with Fowler’s law for photoemission on metals. The Fowler’s law exponent for the graphene-based nanodiode is almost twice that of a thin gold film based diode; the graphene-based nanodiode also has a weak dependence on light intensity—both are significant evidence for CM in graphene. Furthermore, doping in graphene significantly modifies the quantum efficiency by changing the Schottky barrier. The CM phenomenon observed on the graphene/TiO2 nanodiodes can lead to intriguing applications of viable graphene-based light harvesting.

  14. Optoelectronic properties of Zn 0.52Se 0.48/Si Schottky diodes

    Science.gov (United States)

    Venkatachalam, S.; Kumar, Rajendra; Mangalaraj, D.; Narayandass, Sa. K.; Kim, Kyunghae; Yi, Junsin

    2004-12-01

    Zn0.52Se0.48/Si Schottky diodes are fabricated by depositing zinc selenide (Zn0.52Se0.48) thin films onto Si(1 0 0) substrates by vacuum evaporation technique. Rutherford backscattering spectrometry (RBS) analysis shows that the deposited films are nearly stoichiometric in nature. X-ray diffractogram of the films reveals the preferential orientation of the films along (1 1 1) direction. Structural parameters such as crystallite size (D), dislocation density (δ), strain (ε), and the lattice parameter are calculated as 29.13 nm, 1.187 × 10-15 lin/m2, 1.354 × 10-3 lin-2 m-4 and 5.676 × 10-10 m respectively. From the I-V measurements on the Zn0.52Se0.48/p-Si Schottky diodes, ideality and diode rectification factors are evaluated, as 1.749 (305 K) and 1.04 × 104 (305 K) respectively. The built-in potential, effective carrier concentration (NA) and barrier height were also evaluated from C-V measurement, which are found to be 1.02 V, 5.907 × 1015 cm-3 and 1.359 eV respectively.

  15. Structural, morphological, optical and electrical properties of Schottky diodes based on CBD deposited ZnO:Cu nanorods

    Science.gov (United States)

    Mwankemwa, Benard S.; Legodi, Matshisa J.; Mlambo, Mbuso; Nel, Jackie M.; Diale, Mmantsae

    2017-07-01

    Undoped and copper doped zinc oxide (ZnO) nanorods have been synthesized by a simple chemical bath deposition (CBD) method at a temperature of 90 °C. Structural, morphological, optical and electrical properties of the synthesized ZnO nanorods were found to be dependent on the Cu doping percentage. X-ray diffraction (XRD) patterns revealed strong diffraction peaks of hexagonal wurtzite of ZnO, and no impurity phases from metallic zinc or copper. Scanning electron microscopy (SEM) images showed changes in diameter and shape of nanorods, where by those doped with 2 at.% and 3 at.% aggregated and became compact. Selected area electron diffraction (SAED) patterns indicates high quality, single crystalline wurtzite structure ZnO and intensities of bright spots varied with copper doping concentration. UV-visible absorption peaks of ZnO red shifted with increasing copper doping concentration. Raman studies demonstrated among others, strong and sharp E2 (low) and E2 (high) optical phonon peaks confirming crystal structure of ZnO. Current-voltage measurements based on the gold/ZnO nanorods/ITO showed good rectifying behavior of the Schottky diode. The predicted Schottky barrier height of 0.60 eV was obtained which is not far from the theoretical Schottky-Mott value of 0.80 eV.

  16. Schottky diode characteristics and 1/f noise of high sensitivity reduced graphene oxide/Si heterojunction photodetector

    Science.gov (United States)

    Zhu, Miao; Li, Xinming; Li, Xiao; Zang, Xiaobei; Zhen, Zhen; Xie, Dan; Fang, Ying; Zhu, Hongwei

    2016-03-01

    Reduced graphene oxide (RGO)/Si Schottky diode has been reported nowadays to show excellent performances in photodetection and other photoelectrical devices. Different from pure graphene, there are large amounts of function groups and structural defects left on the base plane of RGO, which may influence the interfacial properties of RGO/Si Schottky diode. Herein, the barrier inhomogeneity and junction characteristics were systematically investigated to help to describe the interface of RGO/Si diode. From the perspective of its applications, the influences of gas molecule and noise properties are considered to be important. Thus, the photovoltaic performance of RGO/Si devices in air and vacuum is investigated to analyze their effects. Meanwhile, 1/f noise of RGO/Si diodes is investigated under air/vacuum conditions and varied temperatures. It is found that the devices in vacuum and under higher power incident light show much lower 1/f noise. These results are meaningful to the noise control and performance improvement in the development of Schottky diode based devices.

  17. Influence of annealing temperature on the electrical and structural properties of palladium Schottky contacts on n-type 4H-SiC

    Science.gov (United States)

    Ramesha, C. K.; Rajagopal Reddy, V.

    2014-12-01

    We have investigated the electrical and structural properties of Pd/4H-SiC Schottky diodes as a function of annealing temperature using I-V, C-V, AES and XRD measurements. The barrier height (BH) of the as-deposited Pd/4H-SiC Schottky diode is found to be 0.71 eV (I-V) and 1.18 eV (C-V), respectively. When the Pd/4H-SiC Schottky diode is annealed at 300 °C, a maximum BH is achieved and corresponding values are 0.89 eV (I-V) and 1.30 eV (C-V). Further, an increase in annealing temperature up to 400 °C, the BH decreases to 0.81 eV (I-V) and 1.20 eV (C-V). Using Cheung's functions, the barrier height (ϕb), ideality factor (n), and series resistance (Rs) are also calculated. Experimental results clearly indicate that the optimum annealing temperature for the Pd Schottky contact to 4H-SiC is 300 °C. According to the Auger electron spectroscopy (AES) and X-ray diffraction (XRD) results, the formation of interfacial phases at the Pd/4H-SiC interface could be the reason for the increase or decrease in BH upon annealing at elevated temperatures. The overall surface morphology of the Pd/4H-SiC Schottky diode is fairly smooth upon annealing temperatures.

  18. Effects of 5.4 MeV alpha-particle irradiation on the electrical properties of nickel Schottky diodes on 4H-SiC

    Science.gov (United States)

    Omotoso, E.; Meyer, W. E.; Auret, F. D.; Paradzah, A. T.; Diale, M.; Coelho, S. M. M.; Janse van Rensburg, P. J.; Ngoepe, P. N. M.

    2015-12-01

    Current-voltage, capacitance-voltage and conventional deep level transient spectroscopy at temperature ranges from 40 to 300 K have been employed to study the influence of alpha-particle irradiation from an 241Am source on Ni/4H-SiC Schottky contacts. The nickel Schottky barrier diodes were resistively evaporated on n-type 4H-SiC samples of doping density of 7.1 × 1015 cm-3. It was observed that radiation damage caused an increase in ideality factors of the samples from 1.04 to 1.07, an increase in Schottky barrier height from 1.25 to 1.31 eV, an increase in series resistance from 48 to 270 Ω but a decrease in saturation current density from 55 to 9 × 10-12 A m-2 from I-V plots at 300 K. The free carrier concentration of the sample decreased slightly after irradiation. Conventional DLTS showed peaks due to four deep levels for as-grown and five deep levels after irradiation. The Richardson constant, as determined from a modified Richardson plot assuming a Gaussian distribution of barrier heights for the as-grown and irradiated samples were 133 and 151 A cm-2 K-2, respectively. These values are similar to literature values.

  19. Effects of 5.4 MeV alpha-particle irradiation on the electrical properties of nickel Schottky diodes on 4H–SiC

    Energy Technology Data Exchange (ETDEWEB)

    Omotoso, E. [Department of Physics, University of Pretoria, Private Bag X20, Hatfield 0028 (South Africa); Department of Physics, Obafemi Awolowo University, Ile-Ife 220005 (Nigeria); Meyer, W.E.; Auret, F.D.; Paradzah, A.T.; Diale, M.; Coelho, S.M.M.; Janse van Rensburg, P.J.; Ngoepe, P.N.M. [Department of Physics, University of Pretoria, Private Bag X20, Hatfield 0028 (South Africa)

    2015-12-15

    Current–voltage, capacitance–voltage and conventional deep level transient spectroscopy at temperature ranges from 40 to 300 K have been employed to study the influence of alpha-particle irradiation from an {sup 241}Am source on Ni/4H–SiC Schottky contacts. The nickel Schottky barrier diodes were resistively evaporated on n-type 4H–SiC samples of doping density of 7.1 × 10{sup 15} cm{sup −3}. It was observed that radiation damage caused an increase in ideality factors of the samples from 1.04 to 1.07, an increase in Schottky barrier height from 1.25 to 1.31 eV, an increase in series resistance from 48 to 270 Ω but a decrease in saturation current density from 55 to 9 × 10{sup −12} A m{sup −2} from I–V plots at 300 K. The free carrier concentration of the sample decreased slightly after irradiation. Conventional DLTS showed peaks due to four deep levels for as-grown and five deep levels after irradiation. The Richardson constant, as determined from a modified Richardson plot assuming a Gaussian distribution of barrier heights for the as-grown and irradiated samples were 133 and 151 A cm{sup −2} K{sup −2}, respectively. These values are similar to literature values.

  20. High-performance single CdS nanowire (nanobelt) Schottky junction solar cells with Au/graphene Schottky electrodes.

    Science.gov (United States)

    Ye, Yu; Dai, Yu; Dai, Lun; Shi, Zujin; Liu, Nan; Wang, Fei; Fu, Lei; Peng, Ruomin; Wen, Xiaonan; Chen, Zhijian; Liu, Zhongfan; Qin, Guogang

    2010-12-01

    High-performance single CdS nanowire (NW) as well as nanobelt (NB) Schottky junction solar cells were fabricated. Au (5 nm)/graphene combined layers were used as the Schottky contact electrodes to the NWs (NBs). Typical as-fabricated NW solar cell shows excellent photovoltaic behavior with an open circuit voltage of ∼0.15 V, a short circuit current of ∼275.0 pA, and an energy conversion efficiency of up to ∼1.65%. The physical mechanism of the combined Schottky electrode was discussed. We attribute the prominent capability of the devices to the high-performance Schottky combined electrode, which has the merits of low series resistance, high transparency, and good Schottky contact to the CdS NW (NB). Besides, a promising site-controllable patterned graphene transfer method, which has the advantages of economizing graphene material and free from additional etching process, was demonstrated in this work. Our results suggest that semiconductor NWs (NBs) are promising materials for novel solar cells, which have potential application in integrated nano-optoelectronic systems.

  1. Plasmonic silicon Schottky photodetectors: The physics behind graphene enhanced internal photoemission

    Science.gov (United States)

    Levy, Uriel; Grajower, Meir; Gonçalves, P. A. D.; Mortensen, N. Asger; Khurgin, Jacob B.

    2017-02-01

    Recent experiments have shown that the plasmonic assisted internal photoemission from a metal to silicon can be significantly enhanced by introducing a monolayer of graphene between the two media. This is despite the limited absorption in a monolayer of undoped graphene (˜π α =2.3 % ). Here we propose a physical model where surface plasmon polaritons enhance the absorption in a single-layer graphene by enhancing the field along the interface. The relatively long relaxation time in graphene allows for multiple attempts for the carrier to overcome the Schottky barrier and penetrate into the semiconductor. Interface disorder is crucial to overcome the momentum mismatch in the internal photoemission process. Our results show that quantum efficiencies in the range of few tens of percent are obtainable under reasonable experimental assumptions. This insight may pave the way for the implementation of compact, high efficiency silicon based detectors for the telecom range and beyond.

  2. Electrical characterization of the organic semiconductor Ag/CuPc/Au Schottky diode

    Institute of Scientific and Technical Information of China (English)

    Mutabar Shah; M. H. Sayyad; Kh. S. Karimov

    2011-01-01

    This paper reports on the fabrication and investigation of a surface-type organic semiconductor copper phthalocyanine (CuPc) based diode. A thin film of CuPc of thickness 100 nm was thermally sublimed onto a glass substrate with preliminary deposited metallic electrodes to form a surface-type Ag/CuPc/Au Schottky diode. The current-voltage characteristics were measured at room temperature under dark conditions. The barrier height was calculated as 1.05 eV. The values of mobility and conductivity was found to be 1.74 x l0-9 cm2/(V.s) and 5.5 x 10-6 Ω-1. cm-1, respectively. At low voltages the device showed ohmic conduction and the space charge limited current conduction mechanisms were dominated at higher voltages.

  3. Stacked mechanical nanogenerator comprising piezoelectric semiconducting nanostructures and Schottky conductive contacts

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhong L [Marietta, GA; Xu, Sheng [Atlanta, GA

    2011-08-23

    An electric power generator includes a first conductive layer, a plurality of semiconducting piezoelectric nanostructures, a second conductive layer and a plurality of conductive nanostructures. The first conductive layer has a first surface from which the semiconducting piezoelectric nanostructures extend. The second conductive layer has a second surface and is parallel to the first conductive layer so that the second surface faces the first surface of the first conductive layer. The conductive nanostructures depend downwardly therefrom. The second conductive layer is spaced apart from the first conductive layer at a distance so that when a force is applied, the semiconducting piezoelectric nanostructures engage the conductive nanostructures so that the piezoelectric nanostructures bend, thereby generating a potential difference across the at semiconducting piezoelectric nanostructures and also thereby forming a Schottky barrier between the semiconducting piezoelectric nanostructures and the conductive nanostructures.

  4. Analysis of Reverse-Bias Leakage Current Mechanisms in Metal/GaN Schottky Diodes

    Directory of Open Access Journals (Sweden)

    P. Pipinys

    2010-01-01

    Full Text Available Temperature-dependent reverse-bias current-voltage characteristics obtained by other researchers for Schottky diodes fabricated on GaN are reinterpreted in terms of phonon-assisted tunneling (PhAT model. Temperature dependence of reverse-bias leakage current is shown could be caused by the temperature dependence of electron tunneling rate from traps in the metal-semiconductor interface to the conduction band of semiconductor. A good fit of experimental data with the theory is received in a wide temperature range (from 80 K to 500 K using for calculation the effective mass of 0.222 me. and for the phonon energy the value of 70 meV. The temperature and bias voltages dependences of an apparent barrier height (activation energy are also explicable in the framework of the PhAT model.

  5. Schottky contacts in germanium nanowire network devices synthesized from nickel seeds

    Science.gov (United States)

    Gouveia, R. C.; Rodrigues, A. D.; Leite, E. R.; Chiquito, A. J.

    2016-10-01

    This paper presents reliable process to the synthesis of germanium nanowires by the vapor-liquid-solid method using nickel as an alternative catalyst to gold, the most commonly used metal, without toxic gas precursors. The structural study showed single-crystalline germanium nanowires with diamond structure, lengths of tens of microns and diameters smaller than 40 nm. The reduced dimensions of the nanowires led to phonons localization effect, with correlation lengths of the same order of the nanowires diameters. Additionally, the analysis of electronic properties of metal-nanowire-metal devices indicated the presence of Schottky barriers, whose values depend linearly on temperature. This linear dependence was assigned to the tunneling process through an insulator layer (mostly GeOx) at the metal-semiconductor interface. These results point to the existence of another channel for electrons transference from metal to semiconductor being very significant to electronic devices fabrication.

  6. Plasmonic silicon Schottky photodetectors: The physics behind graphene enhanced internal photoemission

    Directory of Open Access Journals (Sweden)

    Uriel Levy

    2017-02-01

    Full Text Available Recent experiments have shown that the plasmonic assisted internal photoemission from a metal to silicon can be significantly enhanced by introducing a monolayer of graphene between the two media. This is despite the limited absorption in a monolayer of undoped graphene ( ∼ π α = 2.3 % . Here we propose a physical model where surface plasmon polaritons enhance the absorption in a single-layer graphene by enhancing the field along the interface. The relatively long relaxation time in graphene allows for multiple attempts for the carrier to overcome the Schottky barrier and penetrate into the semiconductor. Interface disorder is crucial to overcome the momentum mismatch in the internal photoemission process. Our results show that quantum efficiencies in the range of few tens of percent are obtainable under reasonable experimental assumptions. This insight may pave the way for the implementation of compact, high efficiency silicon based detectors for the telecom range and beyond.

  7. High performance visible-near-infrared PbS-quantum-dots/indium Schottky diodes for photodetectors

    Science.gov (United States)

    Mi, Longfei; Wang, Hui; Zhang, Yan; Yao, Xudong; Chang, Yajing; Li, Guopeng; Li, Guohua; Jiang, Yang

    2017-02-01

    Here we fabricate self-powered photodetectors based on PbS-quantum-dots/indium Schottky barrier diodes successfully. These devices exhibit excellent repeatability and stability at a high frequency (up to1 MHz), and show a typical fast rise time/fall time of ˜0.8 μs/3.2 μs. They also show excellent rectification ratios up to 104 with bias from -0.5 V to +0.5 V in the dark and a pronounced photovoltaic performance under light illumination. Moreover, the devices demonstrate high sensitivity in weak light illumination detection (detectivity) approaching 1012 Jones and low noise currents <1 pAHz-1/2. These findings suggest great application potential of PbS-quantum-dots for advanced fast response, low noise current, high detectivity and high stability photodetectors.

  8. Bunch Length Monitoring at the A0 Photoinjector Using a Quasi-Optical Schottky Detector

    Energy Technology Data Exchange (ETDEWEB)

    Kazakevich, G.; Davidsaver, M.; Edwards, H.; Fliller, R.; Koeth, T.; Lumpkin, A.; Nagaitsev, S.; Ruan, J.; Thurman-Keup, R.; /Fermilab; Jeong, Y.U.; /KAERI, Taejon; Kubarev, V.; /Novosibirsk, IYF

    2009-05-01

    Noninvasive bunch duration monitoring has a crucial importance for modern accelerators intended for short wavelength FEL's, colliders and in some beam dynamics experiments. Monitoring of the bunch compression in the Emittance Exchange Experiment at the A0 Photoinjector was done using a parametric presentation of the bunch duration via Coherent Synchrotron Radiation (CSR) emitted in a dipole magnet and measured with a wideband quasi-optical Schottky Barrier Detector (SBD). The monitoring resulted in a mapping of the quadrupole parameters allowing a determination of the region of highest compression of the bunch in the sub-picosecond range. The obtained data were compared with those measured using the streak camera. A description of the technique and the results of simulations and measurements are presented and discussed in this report.

  9. Surface-plasmon-enhanced photodetection in planar Au-GaAs Schottky junctions

    Energy Technology Data Exchange (ETDEWEB)

    Daboo, C.; Baird, M.J.; Hughes, H.P. (PCS Group, Cavendish Lab., Cambridge (UK)); Apsley, N. (Royal Signals and Radar Establishment, Great Malvern (UK)); Jones, G.A.C.; Frost, J.E.F.; Peacock, D.C.; Ritchie, D.A. (Semiconductor Physics Group, Cavendish Lab., Cambridge (UK))

    1990-08-01

    Surface plasmon resonances have been used to enhance the quantum efficiency in a gold on n-type GaAs Schottky barrier on a suitable prism coupler in the Kretschmann-Raether attenuated total reflection geometry. We have investigated the gold thickness dependence of reflectivity and quantum efficiency for p-polarized and s-polarized light of a wavelength 1152 nm, below the GaAs band gap. Theoretical modelling of the reflectivity and quantum efficiency has been carried out. Both the experimental data and modelling indicate that optimum coupling to the surface plasmon, evidenced by a minimum in reflectivity with a corresponding peak in quantum efficiency for p-polarized light only, occurs for a gold thickness of about 40 nm. (orig.).

  10. Electromechanical resistive switching via back-to-back Schottky junctions

    Science.gov (United States)

    Li, Lijie

    2015-09-01

    The physics of the electromechanical resistive switching is uncovered using the theory of back-to-back Schottky junctions combined with the quantum domain space charge transport. A theoretical model of the basic element of resistive switching devices realized by the metal-ZnO nanowires-metal structure has been created and analyzed. Simulation results show that the reverse biased Schottky junction and the air gap impedance dominate the current-voltage relation at higher external voltages; thereby electromechanically varying the air gap thickness causes the device exhibit resistive tuning characteristics. As the device dimension is in nanometre scale, investigation of the model based on quantum mechanics has also been conducted.

  11. SiC-based Schottky diode gas sensors

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, G.W.; Neudeck, P.G.; Chen, L.Y. [National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center; Knight, D. [Cortez/NASA Lewis Research Center, Cleveland, OH (United States); Liu, C.C.; Wu, Q.H. [Electronics Design Center, Case Western Reserve Univ., Cleveland, OH (United States)

    1998-08-01

    Silicon carbide based Schottky diode gas sensors are being developed for high temperature applications such as emission measurements. Two different types of gas sensitive diodes will be discussed in this paper. By varying the structure of the diode, one can affect the diode stability as well as the diode sensitivity to various gases. It is concluded that the ability of SiC to operate as a high temperature semiconductor significantly enhances the versatility of the Schottky diode gas sensing structure and will potentially allow the fabrication of a SiC-based gas sensor array for versatile high temperature gas sensing applications. (orig.) 6 refs.

  12. SiC-Based Schottky Diode Gas Sensors

    Science.gov (United States)

    Hunter, Gary W.; Neudeck, Philip G.; Chen, Liang-Yu; Knight, Dak; Liu, Chung-Chiun; Wu, Quing-Hai

    1997-01-01

    Silicon carbide based Schottky diode gas sensors are being developed for high temperature applications such as emission measurements. Two different types of gas sensitive diodes will be discussed in this paper. By varying the structure of the diode, one can affect the diode stability as well as the diode sensitivity to various gases. It is concluded that the ability of SiC to operate as a high temperature semiconductor significantly enhances the versatility of the Schottky diode gas sensing structure and will potentially allow the fabrication of a SiC-based gas sensor arrays for versatile high temperature gas sensing applications.

  13. Modelling the inhomogeneous SiC Schottky interface

    OpenAIRE

    Gammon, P. M.; Pérez-Tomás, Amador; Shah, V A; Vavasour, O.; Donchev, E.; J.S. Pang; Myronov, Maksym; Fisher, Craig A.; Jennings, M. R.; Leadley, D. R.; Mawby, P. A. (Philip A.)

    2013-01-01

    For the first time, the I-V-T dataset of a Schottky diode has been accurately modelled, parameterised, and fully fit, incorporating the effects of interface inhomogeneity, patch pinch-off and resistance, and ideality factors that are both heavily temperature and voltage dependent. A Ni/SiC Schottky diode is characterised at 2 K intervals from 20 to 320 K, which, at room temperature, displays low ideality factors (n  8), voltage dependent ideality factors and evidence of the so-called "thermio...

  14. Effects of Annealing on Electrical Characteristics and Current Transport Mechanisms of the Y/ p-GaN Schottky Diode

    Science.gov (United States)

    Reddy, V. Rajagopal; Asha, B.; Choi, Chel-Jong

    2016-07-01

    This study investigates the effects of annealing on the electrical properties and current transport mechanism of Y/ p-GaN Schottky barrier diodes (SBDs). We found no significant change in the surface morphology of the Y Schottky contacts during the annealing process. The Schottky barrier height (SBH) of the as-deposited Y/ p-GaN SBD was estimated to be 0.95 eV ( I- V)/1.19 eV ( C- V). The SBH increased upon annealing at 400°C and 500°C, and then decreased slightly with annealing at 600°C. Thus the maximum SBH of the Y/ p-GaN SBD was achieved at 500°C, with values of 1.01 eV ( I- V)/1.29 eV ( C- V). In addition, the SBH values were estimated by Cheung's, Norde, and Ψs- V plots and were found to be in good agreement with one another. Series resistance ( R S) values were also calculated by I- V, Cheung's, and Norde functions at different annealing temperatures, with results showing a decrease in the interface state density of the SBD with annealing at 500°C, followed by a slight increase upon annealing at 600°C. The forward-bias current transport mechanism of SBD was investigated by the log I-log V plot at different annealing temperatures. Our investigations revealed that the Poole-Frenkel emission mechanism dominated the reverse leakage current in Y/ p-GaN SBD at all annealing temperatures.

  15. Electric field breakdown of lateral-type Schottky diodes formed on lightly doped homoepitaxial diamond

    Science.gov (United States)

    Teraji, Tokuyuki; Koizumi, Satoshi; Koide, Yasuo; Ito, Toshimichi

    2008-07-01

    The reverse current of lateral-type Schottky diodes fabricated on p-type homoepitaxial diamond was analyzed by changing the distance between Schottky and Ohmic electrodes and the metal materials in the Schottky electrodes. The maximum electric field at breakdown was 0.56 MV cm -1 for the Au Schottky contact and less than 0.26 MV cm -1 for the Al Schottky contact. The breakdown voltage depended on the electrode distance when the diamond surface was revealed in vacuum, whereas the Schottky diodes sustained the applied voltage of 500 V, corresponding to 0.69 MV cm -1, after covering of the diamond surface with an insulating liquid. Diamond surface protection is an indispensable technique for fabrication of high-voltage Schottky diodes based on diamond.

  16. A double barrier memristive device

    Science.gov (United States)

    Hansen, M.; Ziegler, M.; Kolberg, L.; Soni, R.; Dirkmann, S.; Mussenbrock, T.; Kohlstedt, H.

    2015-09-01

    We present a quantum mechanical memristive Nb/Al/Al2O3/NbxOy/Au device which consists of an ultra-thin memristive layer (NbxOy) sandwiched between an Al2O3 tunnel barrier and a Schottky-like contact. A highly uniform current distribution for the LRS (low resistance state) and HRS (high resistance state) for areas ranging between 70 μm2 and 2300 μm2 were obtained, which indicates a non-filamentary based resistive switching mechanism. In a detailed experimental and theoretical analysis we show evidence that resistive switching originates from oxygen diffusion and modifications of the local electronic interface states within the NbxOy layer, which influences the interface properties of the Au (Schottky) contact and of the Al2O3 tunneling barrier, respectively. The presented device might offer several benefits like an intrinsic current compliance, improved retention and no need for an electric forming procedure, which is especially attractive for possible applications in highly dense random access memories or neuromorphic mixed signal circuits.

  17. A detailed study of the effect of Schottky barrier on the dark current density-voltage characteristics of CdS/CdTe solar cells*%肖特基势垒对CdS/CdTe薄膜电池J-V 暗性能的影响*

    Institute of Scientific and Technical Information of China (English)

    赵守仁; 黄志鹏; 孙雷; 孙朋超; 张传军; 邬云华; 曹鸿; 王善力; 褚君浩

    2013-01-01

      采用数学模拟方法分析了不同背接触势垒高度(ϕb )对于CdS/CdTe薄膜电池的J-V (电流密度-电压)方程的影响,得出了势垒高度与roll-over的变化对应关系。采用相应Cu/Mo背电极的CdS/CdTe薄膜电池在220-300 K的变温J-V 曲线的数值分析与理论分析相对照,分析了背势垒对于J-V 曲线拟合参数的影响。修正了ϕb与反向饱和电流(Jb0)关系式,理论与实验符合得非常好。%Numerical modeling is used to obtain insight into the details of the effect of back contact barrier height (ϕb ) on the dark current density-voltage characteristics of CdS/CdTe solar cell. And relation between the roll-over and the barrier height is obtained. Analytic simulations are fitted to the measured current density-voltage curve in a temperature range from 220 to 300 K. And the influence of barrier height on J-V of the CdS/CdTe thin film solar cell with Cu/Mo back contact fitted parameters is discussed. The equation between back contact barrier height (ϕb) and the reverse saturation current density (Jb0) is revised and the experimental data are consistent with the simulation results very well.

  18. Current-conduction mechanisms in Au/n-CdTe Schottky solar cells in the wide temperature range

    Energy Technology Data Exchange (ETDEWEB)

    Fiat, Songuel, E-mail: songulfiat@yahoo.com [Physics Department, Faculty of Arts and Sciences, Gaziosmanpasa University, 60240 Tokat (Turkey); Merdan, Ziya [Physics Department, Faculty of Arts and Sciences, Gazi University, 06500 Ankara (Turkey); Memmedli, Tofig [Physics Department, Faculty of Arts and Sciences, Gazi University, 06500 Ankara (Turkey); National Academy of Science, Institute of Physics, Baku (Azerbaijan)

    2012-07-01

    The current-conduction mechanisms in Au/n-CdTe Schottky solar cells have been investigated by considering the series resistance (R{sub s}) effect in the temperature range 120-380 K. The obtained values of main electrical parameters such as zero-bias barrier height ({Phi}{sub bo}), ideality factor (n) and R{sub s} were found strongly function of temperature. While the {Phi}{sub bo} increases, the n decreases with the increasing temperature. Such behavior can be explained on the basis of the thermionic emission (TE) theory with the Gaussian distribution (GD) of the barrier height (BH) being related to inhomogeneities at the metal/semiconductor (M/S) interface. The results show that the conduction mechanism in Au/n-CdTe Schottky solar cells can be successfully explained on the basis of the TE mechanism with a GD of the BHs. In addition, the capacitance-voltage (C-V) characteristics of Au/n-CdTe solar cells have been investigated at room temperature and 1 MHz.

  19. Highly sensitive wide bandwidth photodetector based on internal photoemission in CVD grown p-type MoS2/graphene Schottky junction.

    Science.gov (United States)

    Vabbina, PhaniKiran; Choudhary, Nitin; Chowdhury, Al-Amin; Sinha, Raju; Karabiyik, Mustafa; Das, Santanu; Choi, Wonbong; Pala, Nezih

    2015-07-22

    Two dimensional (2D) Molybdenum disulfide (MoS2) has evolved as a promising material for next generation optoelectronic devices owing to its unique electrical and optical properties, such as band gap modulation, high optical absorption, and increased luminescence quantum yield. The 2D MoS2 photodetectors reported in the literature have presented low responsivity compared to silicon based photodetectors. In this study, we assembled atomically thin p-type MoS2 with graphene to form a MoS2/graphene Schottky photodetector where photo generated holes travel from graphene to MoS2 over the Schottky barrier under illumination. We found that the p-type MoS2 forms a Schottky junction with graphene with a barrier height of 139 meV, which results in high photocurrent and wide spectral range of detection with wavelength selectivity. The fabricated photodetector showed excellent photosensitivity with a maximum photo responsivity of 1.26 AW(-1) and a noise equivalent power of 7.8 × 10(-12) W/√Hz at 1440 nm.

  20. Behavior of temperature dependent electrical properties of Pd/Au Schottky contact to GaN grown on Si substrate by MBE

    Science.gov (United States)

    Singh Nirwal, Varun; Rao Peta, Koteswara

    2016-12-01

    We investigated the effect of temperature on the behavior of electrical properties of Pd/Au Schottky contact to GaN/Si (111) in the temperature range of 125-325 K in steps of 25 K using current-voltage (I-V) and capacitance-voltage (C-V) analysis. The Schottky barrier height (ϕ I-V ) and ideality factor is calculated using standard thermionic emission theory. The value of ϕ I-V was found to increase from 0.41 ± 0.002 eV to 0.79 ± 0.008 eV when temperature varied from 125 to 325 K. The ideality factor of diodes also decreased from 5.91 ± 0.01 to 1.03 ± 0.05 with increase in temperature. The series resistance (R s) is calculated using Cheung’s method and it is observed that the value of R s decreased from 74.40 ± 0.32 Ω to 58.59 ± 0.11 Ω when the temperature increased from 125 to 325 K. Barrier height (ϕ C-V ) and effective carrier concentration (Nd ) is also reported from C-V characteristics as a function of temperature and the value of ϕ C-V was found to decrease with increase in temperature. The behavior of barrier heights obtained from I-V and C-V characteristics is different due to difference in the nature of measurement techniques. The deviation of conventional Richardson’s constant from theoretical value of GaN is due to unusual behavior of temperature dependent electrical properties and barrier inhomogeneity. This is successfully explained by assuming the double Gaussian distribution of inhomogeneous barrier heights of Au/Pd/GaN/Si Schottky diode.

  1. On the electrical behavior of V2O5/4H-SiC Schottky diodes

    Science.gov (United States)

    Bellone, S.; Di Benedetto, L.; Rubino, A.

    2013-06-01

    A complete analysis of the rectifying behavior of V2O5/4H-SiC (divanadium pentoxide/4H polytype of silicon carbide) junction is reported. The analysis of forward and reverse JD-VD curves of samples fabricated with 5 nm-thick V2O5 films shows that the carrier transport across junction is dominated by the field enhanced thermionic emission mechanism. All the physical and electrical parameters, such as Schottky barrier height, ideality factor, and series resistance, have been evaluated from temperature behavior of JD-VD curves in the range 100-425 K and from CD-VD measurements. It is shown that the barrier height extracted from measurements can be justified in terms of inhomogeneities localized at the interface.

  2. Accurate surface potential determination in Schottky diodes by the use of a correlated current and capacitance voltage measurements.Application to n-InP

    Institute of Scientific and Technical Information of China (English)

    Ali Ahaitouf; Abdelaziz Ahaitouf; Jean Paul Salvestrini; Hussein Srour

    2011-01-01

    Based on current voltage (I-Vg) and capacitance voltage (C-Vg) measurements,a reliable procedure is proposed to determine the effective surface potential Vd (Vg) in Schottky diodes.In the framework of thermionic emission,our analysis includes both the effect of the series resistance and the ideality factor,even voltage dependent.This technique is applied to n-type indium phosphide (n-InP) Schottky diodes with and without an interfacial layer and allows us to provide an interpretation of the observed peak on the C-Vg measurements.The study clearly shows that the depletion width and the flat band barrier height deduced from C-Vg,which are important parameters directly related to the surface potential in the semiconductor,should be estimated within our approach to obtain more reliable information.

  3. ON-state characteristics of proton irradiated 4H-SiC Schottky diode: The calibration of model parameters for device simulation

    Science.gov (United States)

    Vobecký, J.; Hazdra, P.; Záhlava, V.; Mihaila, A.; Berthou, M.

    2014-04-01

    4H silicon carbide Schottky diodes were irradiated by 550 keV protons with the aim to place the ion range into the low-doped n-type epitaxial layer. The diodes were characterized using DLTS, C-V profiling and forward I-V curves. Calibration procedure of model parameters for device simulation has been carried out. It is based on modeling the doping compensation of the n-type epitaxial layer caused by the deep acceptor levels resulting from radiation damage. It is shown that the agreement of simulated and measured forward I-V curves of proton irradiated diodes can be achieved, if the profiles of deep levels are calibrated with respect to irradiation dose, the degradation of electron mobility due to charged deep levels is accounted of and the Schottky barrier height is properly adjusted. The proposed methodology introduces a starting point for exact calibration of ion irradiated SiC unipolar devices.

  4. 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

  5. Extracted Electronic Parameters of a Novel Ag/SnO2:In/Si/Au Schottky Diode for Solar Cell Application

    Directory of Open Access Journals (Sweden)

    Mostefa Benhaliliba

    2015-06-01

    Full Text Available The effect of indium on the characteristics of Ag / SnO2 : In / Si / Au Schottky diode (SD is studied. The electronic parameters, ideal factor, the effective barrier, flat band barrier height, the series resistance, the saturation current density of the diodes were extracted from the current voltage (I-V and capacitance voltage (C-V characteristics. The series resistance (Rs determined by Cheung method increases (508-534 Ω with In doping level while the barrier height still constant around 0.57 V. Norde approximation gives a similar barrier height values of 0.69 V but the series resistance reaches higher values of 5500 Ω.

  6. Measuring the Electronic Properties of DNA-Specific Schottky Diodes Towards Detecting and Identifying Basidiomycetes DNA

    Science.gov (United States)

    Periasamy, Vengadesh; Rizan, Nastaran; Al-Ta'Ii, Hassan Maktuff Jaber; Tan, Yee Shin; Tajuddin, Hairul Annuar; Iwamoto, Mitsumasa

    2016-07-01

    The discovery of semiconducting behavior of deoxyribonucleic acid (DNA) has resulted in a large number of literatures in the study of DNA electronics. Sequence-specific electronic response provides a platform towards understanding charge transfer mechanism and therefore the electronic properties of DNA. It is possible to utilize these characteristic properties to identify/detect DNA. In this current work, we demonstrate a novel method of DNA-based identification of basidiomycetes using current-voltage (I-V) profiles obtained from DNA-specific Schottky barrier diodes. Electronic properties such as ideality factor, barrier height, shunt resistance, series resistance, turn-on voltage, knee-voltage, breakdown voltage and breakdown current were calculated and used to quantify the identification process as compared to morphological and molecular characterization techniques. The use of these techniques is necessary in order to study biodiversity, but sometimes it can be misleading and unreliable and is not sufficiently useful for the identification of fungi genera. Many of these methods have failed when it comes to identification of closely related species of certain genus like Pleurotus. Our electronics profiles, both in the negative and positive bias regions were however found to be highly characteristic according to the base-pair sequences. We believe that this simple, low-cost and practical method could be useful towards identifying and detecting DNA in biotechnology and pathology.

  7. Gold nanoparticles deposited on linker-free silicon substrate and embedded in aluminum Schottky contact.

    Science.gov (United States)

    Gorji, Mohammad Saleh; Razak, Khairunisak Abdul; Cheong, Kuan Yew

    2013-10-15

    Given the enormous importance of Au nanoparticles (NPs) deposition on Si substrates as the precursor for various applications, we present an alternative approach to deposit Au NPs on linker-free n- and p-type Si substrates. It is demonstrated that, all conditions being similar, there is a significant difference between densities of the deposited NPs on both substrates. The Zeta-potential and polarity of charges surrounding the hydroxylamine reduced seeded growth Au NPs, are determined by a Zetasizer. To investigate the surface properties of Si substrates, contact angle measurement is performed. Field-emission scanning electron microscope is then utilized to distinguish the NPs density on the substrates. Finally, Al/Si Schottky barrier diodes with embedded Au NPs are fabricated, and their structural and electrical characteristics are further evaluated using an energy-filtered transmission electron microscope and current-voltage measurements, respectively. The results reveal that the density of NPs is significantly higher on n-type Si substrate and consequently has more pronounced effects on the electrical characteristics of the diode. It is concluded that protonation of Si-OH group on Si surface in low pH is responsible for the immobilization of Au NPs, which eventually contributes to the lowering of barrier height and enhances the electrical characteristics.

  8. PEDOT:PSS Schottky contacts on annealed ZnO films

    Institute of Scientific and Technical Information of China (English)

    Zhu Ya-Bin; Hu Wei; Na Jie; He Fan; Zhou Yue-Liang; Chen Cong

    2011-01-01

    Polycrystalline ZnO and ITO films on Si02 substrates are prepared by radio frequency (RF)reactive magnetron sputtering. Schottky contacts are fabricated on ZnO films by spin coating with a high conducting polymer, poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate)(PEDOT:PSS)as the metal electrodes. The current-voltage measurements for samples on unannealed ZnO films exhibit rectifying behaviours with a barrier height of 0.72 eV(n=1.93).The current for the sample is improved by two orders of magnitude at I V after annealing ZnO film at 850℃, whose barrier height is 0.75 eV with an ideality factor of 1.12. X-ray diffraction, atomic force microscopy and scanning electron microscopy are used to study the properties of the PEDOT:PSS/ZnO/ITO/SiO2. The results are useful for applications such as metal-semiconductor field-effect transistors and UV photodetectors.

  9. Ambient organic molecular passivation of Si yields near-ideal, Schottky-Mott limited, junctions

    Directory of Open Access Journals (Sweden)

    Rotem Har-Lavan

    2012-03-01

    Full Text Available We report near-perfect transfer of the electrical properties of oxide-free Si surface, modified by a molecular monolayer, to the interface of a junction made with that modified Si surface. Such behavior is highly unusual for a covalent, narrow bandgap semiconductor, such as Si. Short, ambient atmosphere, room temperature treatment of oxide-free Si(100 in hydroquinone (HQ/alkyl alcohol solutions, fully passivates the Si surface, while allowing controlled change of the resulting surface potential. The junctions formed, upon contacting such surfaces with Hg, a metal that does not chemically interact with Si, follow the Schottky-Mott model for metal-semiconductor junctions closer than ever for Si-based junctions. Two examples of such ideal behavior are demonstrated: a Tuning the molecular surface dipole over 400 mV, with only negligible band bending, by changing the alkyl chain length. Because of the excellent passivation this yields junctions with Hg with barrier heights that follow the change in the Si effective electron affinity nearly ideally. b HQ/ methanol passivation of Si is accompanied by a large surface dipole, which suffices, as interface dipole, to drive the Si into strong inversion as shown experimentally via its photovoltaic effect. With only ∼0.3 nm molecular interlayer between the metal and the Si, our results proves that it is passivation and prevention of metal-semiconductor interactions that allow ideal metal-semiconductor junction behavior, rather than an insulating transport barrier.

  10. Effect of nanopatches on electrical behavior of Ni/n-type Si Schottky diode

    Science.gov (United States)

    Rahmatallahpur, Sh.; Yegane, M.

    2011-04-01

    Topological surface measurement of thin metal film using a conducting probe atomic force microscope (C-AFM) shows that thin metal film deposited on Ni/n-Si Schottky diode (SD) consists of patches. These patches are sets of parallel connected and electrically cooperating nano-contacts of size between 50 and 100nm. Every individual patch acts as an individual diode with different I- V curve, barrier height (BH) and ideality factor ( n). Between these diodes or patches, there are spot field distributions; the patches with different local work functions are in direct electric contact with surrounding patches. As a result, a potential difference between surfaces of patches, the so-called electrostatic spot field Ef, is formed. It is shown that in real metal-semiconductor (MS) contacts, patches with quite different configurations, various geometrical sizes and local work functions are randomly distributed on the surface of metal; hence direction and intensity of spot field are non-uniformly distributed along the surface of metal. There is a linear dependence between barrier height and ideality factor, which is the consequence of reduction of distance of the maximum of BH from the interface. This dependency is the sign of reduction of contribution of a peripheral current.

  11. Electromechanical resistive switching via back-to-back Schottky junctions

    Directory of Open Access Journals (Sweden)

    Lijie Li

    2015-09-01

    Full Text Available The physics of the electromechanical resistive switching is uncovered using the theory of back-to-back Schottky junctions combined with the quantum domain space charge transport. A theoretical model of the basic element of resistive switching devices realized by the metal-ZnO nanowires-metal structure has been created and analyzed. Simulation results show that the reverse biased Schottky junction and the air gap impedance dominate the current-voltage relation at higher external voltages; thereby electromechanically varying the air gap thickness causes the device exhibit resistive tuning characteristics. As the device dimension is in nanometre scale, investigation of the model based on quantum mechanics has also been conducted.

  12. Monte Carlo modelling of Schottky diode for rectenna simulation

    Science.gov (United States)

    Bernuchon, E.; Aniel, F.; Zerounian, N.; Grimault-Jacquin, A. S.

    2017-09-01

    Before designing a detector circuit, the electrical parameters extraction of the Schottky diode is a critical step. This article is based on a Monte-Carlo (MC) solver of the Boltzmann Transport Equation (BTE) including different transport mechanisms at the metal-semiconductor contact such as image force effect or tunneling. The weight of tunneling and thermionic current is quantified according to different degrees of tunneling modelling. The I-V characteristic highlights the dependence of the ideality factor and the current saturation with bias. Harmonic Balance (HB) simulation on a rectifier circuit within Advanced Design System (ADS) software shows that considering non-linear ideality factor and saturation current for the electrical model of the Schottky diode does not seem essential. Indeed, bias independent values extracted in forward regime on I-V curve are sufficient. However, the non-linear series resistance extracted from a small signal analysis (SSA) strongly influences the conversion efficiency at low input powers.

  13. Simulation and measurement of the resonant Schottky pickup

    Institute of Scientific and Technical Information of China (English)

    ZANG Yong-Dong; XIAO Guo-Qing; F.Nolden; P.Hülsmann; Yu. A. Litvinov; C. Peschke; P.Petri; M.S.Sanjari; M. Steck; WU Jun-Xia; ZHAO Tie-Cheng; ZHANG Sheng-Hu; MAO Rui-Shi; XU Hu-Shan; SUN Zhi-Yu; MA Xin-Wen; TU Xiao-Lin

    2011-01-01

    A resonant Schottky pickup with high sensitivity,built by GSI,will be used for nuclear mass and lifetime measurement at CSRe.The basic concepts of Schottky noise signals,a brief introduction of the geometry of the detector,the transient response of the detector,and MAFIA simulated and perturbation measured results of characteristics are presented in this paper.The resonant frequency of the pickup is about 243 MHz and can be slightly changed at a range of 3 MHz.The unloaded quality factor is about 1072 and the shunt impedance is 76 kΩ.The measured results of the characteristics are in agreement with the MAFIA simulations.

  14. ITON Schottky contacts for GaN based UV photodetectors

    Science.gov (United States)

    Vanhove, N.; John, J.; Lorenz, A.; Cheng, K.; Borghs, G.; Haverkort, J. E. M.

    2006-12-01

    Lateral Schottky ultraviolet detectors were fabricated in GaN using indium-tin-oxynitride (ITON) as a contact metal. The GaN semiconductor material was grown on 2 in. sapphire substrate by metal-organic chemical vapor deposition (MOCVD). The Schottky contact has been realized using ITON that has been deposited using sputter techniques. I- V characteristics have been measured with and without UV illumination. The device shows photo-to-dark current ratios of 10 3 at -1 V bias. The spectral responsivity of the UV detectors has been determined. The high spectral responsivity of more than 30 A/W at 240 nm is explained by a high internal gain caused by generation-recombination centers at the ITON/GaN interface. Persistent photocurrent effect has been observed in UV light (on-off) switching operation, time constant and electron capture coefficient of the transition has been determined.

  15. Interdigitated planar Schottky varactor diodes for tunable MMIC applications

    OpenAIRE

    Lucyszyn, Stepan; Green, Ged; Robertson, Ian D.

    1992-01-01

    Techniques are presented for scale modelling interdigitated Planar Schottky Varactor Diodes (PSVDs) using an equivalent circuit model. A selection of low cost GaAs devices, with variations in the finger width and number of anode fingers, have been fabricated, measured and accurately characterized - well into the millimetric frequency range. From the results, a number of useful design rules are presented for the optimal choice of interdigitated PSVD topography. With the use of these rules, a 2...

  16. Examinations of Selected Thermal Properties of Packages of SiC Schottky Diodes

    Directory of Open Access Journals (Sweden)

    Bisewski Damian

    2016-09-01

    Full Text Available This paper describes the study of thermal properties of packages of silicon carbide Schottky diodes. In the paper the packaging process of Schottky diodes, the measuring method of thermal parameters, as well as the results of measurements are presented. The measured waveforms of transient thermal impedance of the examined diodes are compared with the waveforms of this parameter measured for commercially available Schottky diodes.

  17. Silver nanowires-templated metal oxide for broadband Schottky photodetector

    Science.gov (United States)

    Patel, Malkeshkumar; Kim, Hong-Sik; Park, Hyeong-Ho; Kim, Joondong

    2016-04-01

    Silver nanowires (AgNWs)-templated transparent metal oxide layer was applied for Si Schottky junction device, which remarked the record fastest photoresponse of 3.4 μs. Self-operating AgNWs-templated Schottky photodetector showed broad wavelength photodetection with high responsivity (42.4 A W-1) and detectivity (2.75 × 1015 Jones). AgNWs-templated indium-tin-oxide (ITO) showed band-to-band excitation due to the internal photoemission, resulting in significant carrier collection performances. Functional metal oxide layer was formed by AgNWs-templated from ITO structure. The grown ITO above AgNWs has a cylindrical shape and acts as a thermal protector of AgNWs for high temperature environment without any deformation. We developed thermal stable AgNWs-templated transparent oxide devices and demonstrated the working mechanism of AgNWs-templated Schottky devices. We may propose the high potential of hybrid transparent layer design for various photoelectric applications, including solar cells.

  18. Study on the spectral response of the Schottky photodetector of GaN

    Institute of Scientific and Technical Information of China (English)

    He Zheng; Kang Yong; Tang Ying-Wen; Li Xue; Fang Jia-Xiong

    2006-01-01

    The Schottky photodetector was fabricated on GaN epilayers grown by metalorganic chemical vapour deposition(MOCVD). The spectral response of the Schottky photodetector was characterized. A new model is proposed to interpret the characteristic of the spectral response curve of the Schottky photodetectors by introducing a penetrating distance of an incident light at a certain wavelength in the current continuity equation and the interface recombination at the metal-semiconductor rectifying contact. The expressions for the spectral response of the Schottky photodetector are deduced and used successfully to fit the experimental data.

  19. Influence of temperature on Al/p-CuInAlSe2 thin-film Schottky diodes

    Science.gov (United States)

    Parihar, Usha; Ray, Jaymin; Panchal, C. J.; Padha, Naresh

    2016-06-01

    Al/p-CuInAlSe2 Schottky diodes were fabricated using the optimized thin layers of CuInAlSe2 semiconductor. These diodes were used to study their temperature-dependent current-voltage (I-V) and capacitance-voltage (C-V) analysis over a wide range of 233-353 K. Based on these measurements, diode parameters such as ideality factor ( η), barrier height (ϕbo) and series resistance ( R s) were determined from the downward curvature of I-V characteristics using Cheung and Cheung method. The extracted parameters were found to be strongly temperature dependent; ϕbo increases, while η and R s decrease with increasing temperature. This behavior of ϕbo and η with change in temperature has been explained on the basis of barrier inhomogeneities over the MS interface by assuming a Gaussian distribution (GD) of the ϕbo at the interface. GD of barrier height (BH) was confirmed from apparent BH (ϕap) versus q/2 kT plot, and the values of the mean BH and standard deviation (σs) obtained from this plot at zero bias were found to be 1.02 and 0.14 eV, respectively. Also, a modified ln ( {J_{{s}} /T2 } ) - q2 σ_{{s}}2 /2k2 T2 versus q/ kT plot for Al/p-CuInAlSe2 Schottky diodes according to the GD gives ϕbo and Richardson constant ( A ** ) as 1.01 eV and 26 Acm-2 K-2, respectively. The Richardson constant value of 26 Acm-2 K-2 is very close to the theoretical value of 30 Acm-2 K-2. The discrepancy between BHs obtained from I-V and C-V measurements has also been interpreted.

  20. Investigation of current transport parameters of Ti/4H-SiC MPS diode with inhomogeneous barrier

    Institute of Scientific and Technical Information of China (English)

    Song Qing-Wen; Zhang Yu-Ming; Zhang Yi-Men; Chen Feng-Ping; Tang xiao-Yan

    2011-01-01

    The current transport parameters of 4H-SiC merged PiN Schottky (MPS) diode are investigated in a temperature range of 300-520 K. Evaluation of the experimental current-voltage (Ⅰ-Ⅴ) data reveals the decrease in Schottky barrier height φb but an increase in ideality factor n, with temperature decreasing, which suggests the presence of an inhomogeneous Schottky barrier. The current transport behaviours are analysed in detail using the Tung's model and the effective area of the low barrier patches is extracted. It is found that small low barrier patches, making only 4.3% of the total contact, may significantly influence the device electrical characteristics due to the fact that a barrier height of 0.968 eV is much lower than the average barrier height 1.39 eV. This shows that ion implantation in the Schottky contact region of MPS structure may result in a poor Ti/4H-SiC interface quality. In addition, the temperature dependence of the specific on-resistance (Ron-sp), T2.14, is determined between 300 K and 520 K, which is similar to that predicted by a reduction in electron mobility.

  1. 60Co gamma irradiation effects on the the capacitance and conductance characteristics of Au/PMI/n-Si Schottky diodes

    Science.gov (United States)

    Tuğluoğlu, N.; Karadeniz, S.; Yüksel, Ö. F.; Şafak, H.; Kuş, M.

    2015-08-01

    In this work, the perylene-monoimide/n-Si (100) Schottky structures have been fabricated by spin coating process. We have studied the capacitance-voltage ( C- V) and conductance-voltage ( G- V) characteristics of the Au/perylene-monoimide/n-Si diodes at 500 kHz before and after 60Co γ-ray irradiation. The effects of 60Co γ -ray irradiation on the electrical characteristics of a perylene-monoimide/n-Si Schottky diode have been investigated. A decrease both in the capacitance and conductance has been observed after 60Co γ -ray irradiation. This has been attributed to a decrease in the net ionized dopant concentration that occurred as a result of 60Co γ-ray irradiation. Some contact parameters such as barrier height (Φ B ) interface state density ( N ss ) and series resistance ( R s ) have been calculated from the C- V and G- V characteristics of the diode before and after irradiation. It has been observed that the Φ B and N ss values are decreased after the applied radiation, while the R s value is increased.

  2. Solid State Reaction and Operational Stability of Ruthenium Schottky Contact-on-6H-SiC Under Argon Annealing

    Science.gov (United States)

    Munthali, Kinnock V.; Theron, Chris; Auret, F. Danie; Coelho, Sergio M. M.; Njoroge, Eric

    2015-10-01

    Thin films of ruthenium-on-6-hexagonal silicon carbide (6H-SiC) were analysed by Rutherford backscattering spectroscopy (RBS) at various annealing temperatures. Some thin film samples were also analysed by scanning electron microscope (SEM). RBS analysis indicated minimal element diffusion, and formation of ruthenium oxide after annealing at 500°C. Large-scale diffusion of ruthenium (Ru) was observed to commence at 700°C. The SEM images indicated that the as-deposited Ru was disorderly and amorphous. Annealing of the thin film improved the grain quality of Ru. The fabricated Ru-6H-SiC Schottky barrier diodes (SBD) with nickel ohmic contacts showed excellent rectifying behaviour and linear capacitance-voltage characteristics up to an annealing temperature of 900°C. The SBDs degraded after annealing at 1000°C. The degradation of the SBDs is attributed to the inter-diffusion of Ru and Si at the Schottky-substrate interface.

  3. Magnetic tunnel transistor with a perpendicular Co/Ni multilayer sputtered on a Si/Cu(1 0 0) Schottky diode

    Science.gov (United States)

    Vautrin, C.; Lu, Y.; Robert, S.; Sala, G.; Lenoble, O.; Petit-Watelot, S.; Devaux, X.; Montaigne, F.; Lacour, D.; Hehn, M.

    2016-09-01

    We have studied a magnetic tunnel transistor (MTT) structure based on a MgO tunnelling barrier emitter and a [Co/Ni]5/Cu multilayer base on a Si (0 0 1) substrate. Evident links between the Schottky barrier preparation techniques and the properties of perpendicular magnetic anisotropy (PMA) in the [Co/Ni] multilayer have been revealed by combined x-ray diffraction and magnetometry analyses. The Si surface treated by hydrofluoric acid (HF) is found to favour a Cu [1 0 0] texture growth which is detrimental to the [Co/Ni]5 PMA properties. However, a Ta layer insertion can restore the [1 1 1] texture required for the PMA appearance. By carefully engineering the base crystallographic texture structure, we obtain both a good quality of Schottky barrier and PMA property; a magneto-current ratio of 162% has been measured for MTTs with a spin-valve base composed of one magnetic layer having in-plane anisotropy and another one with out-of-plane anisotropy.

  4. An Ultra-Wideband Schottky Diode Based Envelope Detector for 2.5 Gbps signals

    DEFF Research Database (Denmark)

    Cimoli, Bruno; Valdecasa, Guillermo Silva; Granja, Angel Blanco

    2016-01-01

    In this paper an ultra-wideband (UWB) Schottky diode based envelope detector is reported. The detector consists of an input matching network, a Schottky diode and wideband output filtering network. The output network is tailored to demodulate ultra-wideband amplitude shift keying (ASK) signals up...

  5. Transformation of polycrystalline tungsten to monocrystalline tungsten W(100) and its potential application in Schottky emitters

    NARCIS (Netherlands)

    Dokania, A.K.; Hendrikx, R.; Kruit, P.

    2009-01-01

    The electron sources in electron microscopes and electron lithography machines often consist of small diameter W(100) wires, etched to form a sharp tip. The electron emission is facilitated by the Schottky effect, thus the name Schottky emitter. The authors are investigating the feasibility of array

  6. Au/n-InP Schottky diodes using an Al2O3 interfacial layer grown by atomic layer deposition

    Science.gov (United States)

    Kim, Hogyoung; Kim, Min Soo; Yoon, Seung Yu; Choi, Byung Joon

    2017-02-01

    We investigated the effect of an Al2O3 interfacial layer grown by atomic layer deposition on the electrical properties of Au Schottky contacts to n-type InP. Considering barrier inhomogeneity, modified Richardson plots yielded a Richardson constant of 8.4 and 7.5 Acm-2K-2, respectively, for the sample with and without the Al2O3 interlayer (theoretical value of 9.4 Acm-2K-2 for n-type InP). The dominant reverse current flow for the sample with an Al2O3 interlayer was found to be Poole-Frenkel emission. From capacitance-voltage measurements, it was observed that the capacitance for the sample without the Al2O3 interlayer was frequency dependent. Sputter-induced defects as well as structural defects were passivated effectively with an Al2O3 interlayer.

  7. Interface behaviour and electrical performance of ruthenium Schottky contact on 4H-SiC after argon annealing

    Indian Academy of Sciences (India)

    Kinnock V munthali; Chris Theron; F Danie Auret; Sergio M M Coelho

    2015-06-01

    Rutherford backscattering spectrometry (RBS) analysis, carried out at various annealing temperatures, of a thin film of ruthenium on n-type four-hexagonal silicon carbide (4H-SiC) showed the evidence of ruthenium oxidation, ruthenium silicide formation and diffusion of ruthenium into silicon carbide starting from an annealing temperature of 400° C. Ruthenium oxidation was more pronounced, and ruthenium and silicon interdiffusion was very deep after annealing at 800° C. Raman analysis of some samples also showed ruthenium silicide formation and oxidation. The Schottky barrier diodes showed very good linear capacitance–voltage characteristics and excellent forward current–voltage characteristics, despite the occurrence of the chemical reactions and interdiffusion of ruthenium and silicon at ruthenium–silicon–carbide interface, up to an annealing temperature of 800° C.

  8. 4H-SiC Schottky diode arrays for X-ray detection

    Science.gov (United States)

    Lioliou, G.; Chan, H. K.; Gohil, T.; Vassilevski, K. V.; Wright, N. G.; Horsfall, A. B.; Barnett, A. M.

    2016-12-01

    Five SiC Schottky photodiodes for X-ray detection have been electrically characterized at room temperature. One representative diode was also electrically characterized over the temperature range 20°C to 140 °C. The performance at 30 °C of all five X-ray detectors, in both current mode and for photon counting X-ray spectroscopy was investigated. The diodes were fabricated in an array form such that they could be operated as either a 2×2 or 1×3 pixel array. Although the devices showed double barrier heights, high ideality factors and higher than expected leakage current at room temperature (12 nA/cm2 at an internal electric field of 105 kV/cm), they operated as spectroscopic photon counting soft X-ray detectors uncooled at 30 °C. The measured energy resolution (FWHM at 17.4 keV, Mo Kα) varied from 1.36 to 1.68 keV among different diodes.

  9. Spin-dependent electrical conduction in a pentacene Schottky diode explored by electrically detected magnetic resonance

    Science.gov (United States)

    Fukuda, Kunito; Asakawa, Naoki

    2017-02-01

    Reported is the observation of dark spin-dependent electrical conduction in a Schottky barrier diode with pentacene (PSBD) using electrically detected magnetic resonance at room temperature. It is suggested that spin-dependent conduction exists in pentacene thin films, which is explored by examining the anisotropic linewidth of the EDMR signal and current density-voltage (J-V) measurements. The EDMR spectrum can be decomposed to Gaussian and Lorentzian components. The dependency of the two signals on the applied voltage was consistent with the current density-voltage (J-V) of the PSBD rather than that of the electron-only device of Al/pentacene/Al, indicating that the spin-dependent conduction is due to bipolaron formation associated with hole polaronic hopping processes. The applied-voltage dependence of the ratio of intensity of the Gaussian line to the Lorentzian may infer that increasing current density should make conducting paths more dispersive, thereby resulting in an increased fraction of the Gaussian line due to the higher dispersive g-factor.

  10. Correlation Between Morphological Defects, Electron Beam Induced Current Imaging, and the Electrical Properties of 4H-SiC Schottky Diodes

    Energy Technology Data Exchange (ETDEWEB)

    Wang,Y.; Ali, G.; Mikhov, M.; Vaidyanathan, V.; Skromme, B.; Raghothamachar, B.; Dudley, M.

    2005-01-01

    Defects in SiC degrade the electrical properties and yield of devices made from this material. This article examines morphological defects in 4H-SiC and defects visible in electron beam-induced current (EBIC) images and their effects on the electrical characteristics of Schottky diodes. Optical Nomarski microscopy and atomic force microscopy were used to observe the morphological defects, which are classified into 26 types based on appearance alone. Forward and reverse current-voltage characteristics were used to extract barrier heights, ideality factors, and breakdown voltages. Barrier heights decrease about linearly with increasing ideality factor, which is explained by discrete patches of low barrier height within the main contact. Barrier height, ideality, and breakdown voltage all degrade with increasing device diameter, suggesting that discrete defects are responsible. Electroluminescence was observed under reverse bias from microplasmas associated with defects containing micropipes. EBIC measurements reveal several types of features corresponding to recombination centers. The density of dark spots observed by EBIC correlates strongly with ideality factor and barrier height. Most morphological defects do not affect the reverse characteristics when no micropipes are present, but lower the barrier height and worsen the ideality factor. However, certain multiple-tailed defects, irregularly shaped defects and triangular defects with 3C inclusions substantially degrade both breakdown voltage and barrier height, and account for most of the bad devices that do not contain micropipes. Micropipes in these wafers are also frequently found to be of Type II, which do not run parallel to the c axis.

  11. All-back-Schottky-contact thin-film photovoltaics

    Science.gov (United States)

    Nardone, Marco

    2016-02-01

    The concept of All-Back-Schottky-Contact (ABSC) thin-film photovoltaic (TFPV) devices is introduced and evaluated using 2D numerical simulation. Reach-through Schottky junctions due to two metals of different work functions in an alternating, side-by-side pattern along the non-illuminated side generate the requisite built-in field. It is shown that our simulation method quantitatively describes existing data for a recently demonstrated heterojunction thin-film cell with interdigitated back contacts (IBCs) of one metal type. That model is extended to investigate the performance of ABSC devices with bimetallic IBCs within a pertinent parameter space. Our calculations indicate that 20% efficiency is achievable with micron-scale features and sufficient surface passivation. Bimetallic, micron-scale IBCs are readily fabricated using photo-lithographic techniques and the ABSC design allows for optically transparent surface passivation layers that need not be electrically conductive. The key advantages of the ABSC-TFPV architecture are that window layers, buffer layers, heterojunctions, and module scribing are not required because both contacts are located on the back of the device.

  12. Numerical simulation of InGaN Schottky solar cell

    CERN Document Server

    Hamady, Sidi Ould Saad; Fressengeas, Nicolas

    2016-01-01

    The Indium Gallium Nitride (InGaN) III-Nitride ternary alloy has the potentiality to allow achieving high efficiency solar cells through the tuning of its band gap by changing the Indium composition. It also counts among its advantages a relatively low effective mass, high carriers’ mobility, a high absorption coefficient along with good radiation tolerance.However, the main drawback of InGaN is linked to its p-type doping, which is difficult to grow in good quality and on which ohmic contacts are difficult to realize. The Schottky solar cell is a good alternative to avoid the p-type doping of InGaN. In this report, a comprehensive numerical simulation, using mathematically rigorous optimization approach based on state-of-the-art optimization algorithms, is used to find the optimum geometrical and physical parameters that yield the best efficiency of a Schottky solar cell within the achievable device fabrication range. A 18.2% efficiency is predicted for this new InGaN solar cell design.

  13. Temperature dependent simulation of diamond depleted Schottky PIN diodes

    Science.gov (United States)

    Hathwar, Raghuraj; Dutta, Maitreya; Koeck, Franz A. M.; Nemanich, Robert J.; Chowdhury, Srabanti; Goodnick, Stephen M.

    2016-06-01

    Diamond is considered as an ideal material for high field and high power devices due to its high breakdown field, high lightly doped carrier mobility, and high thermal conductivity. The modeling and simulation of diamond devices are therefore important to predict the performances of diamond based devices. In this context, we use Silvaco® Atlas, a drift-diffusion based commercial software, to model diamond based power devices. The models used in Atlas were modified to account for both variable range and nearest neighbor hopping transport in the impurity bands associated with high activation energies for boron doped and phosphorus doped diamond. The models were fit to experimentally reported resistivity data over a wide range of doping concentrations and temperatures. We compare to recent data on depleted diamond Schottky PIN diodes demonstrating low turn-on voltages and high reverse breakdown voltages, which could be useful for high power rectifying applications due to the low turn-on voltage enabling high forward current densities. Three dimensional simulations of the depleted Schottky PIN diamond devices were performed and the results are verified with experimental data at different operating temperatures

  14. Schottky Diode Applications of the Fast Green FCF Organic Material and the Analyze of Solar Cell Characteristics

    Science.gov (United States)

    Çaldiran, Z.; Aydoğan, Ş.; İncekara, Ü.

    2016-05-01

    In this study, a device applications of organic material Fast Green FCF (C37H34N2Na2O10S3Na2) has been investigated. After chemical cleaning process of boron doped H-Si crystals, Al metal was coated on the one surface of crystals by thermal evaporation and fast green organic materials were coated on other surface of crystals with spin coating method (coating parameters; 800 rpm for 60 s). Finally, Ni metal was coated on Fast Green by sputtering and we obtained the Ni/Fast Green FCF/n-Si/Al Schottky type diode. And then we calculated the basic diode parameters of device with current-voltage (I-V) and capacitance- voltage (C-V) measurements at the room temperature. We calculated the ideality factory (n), barrier height (Φb) of rectifing contact from I-V measurements using thermionic emission methods. Furthermore, we calculated ideality factory (n), barrier height (Φb) and series resistance (Rs) of device using Cheung and Norde functions too. The diffusion potential, barrier height, Fermi energy level and donor concentration have been determined from the linear 1/C2-V curves at reverse bias, at room temperature and various frequencies. Besides we measured the current-voltage (I-V) at under light and analyzed the characteristics of the solar cell device.

  15. Schottky bipolar I-MOS: An I-MOS with Schottky electrodes and an open-base BJT configuration for reduced operating voltage

    Science.gov (United States)

    Kannan, N.; Kumar, M. Jagadesh

    2017-04-01

    In this paper, we have proposed a novel impact ionization MOS (I-MOS) structure, called the Schottky bipolar I-MOS, with Schottky source and drain electrodes and utilizing the open-base bipolar junction transistor (BJT) configuration for achieving reduction in the operating voltage of the I-MOS transistor. We report, using 2-D simulations, a low operating voltage (∼1.1 V) and a low subthreshold swing (∼3.6 mV/Decade). For the corresponding p-i-n I-MOS, the operating voltage is ∼5.5 V. The operating voltage of the Schottky bipolar I-MOS is the lowest reported operating voltage for silicon based I-MOS transistors. The nearly 80% reduction in the operating voltage of the Schottky bipolar I-MOS makes it suitable for applications requiring low operating voltages. The Schottky bipolar I-MOS is also expected to have an improved reliability over the p-i-n I-MOS since high energy carriers, induced by impact ionization near the drain, do not have to pass under the gate region in the channel. The use of Schottky contacts instead of heavily doped source and drain regions and the low channel doping level reduces the required thermal budget for device fabrication. The low operating voltage, low subthreshold swing and possibly improved reliability of the Schottky bipolar I-MOS, makes it a potential solution for applications where steep subthreshold slope transistors are being explored as alternative to the conventional MOS transistor.

  16. Carrier-transport mechanism of Er-silicide Schottky contacts to strained-silicon-on-insulator and silicon-on-insulator.

    Science.gov (United States)

    Jyothi, I; Janardhanam, V; Kang, Min-Sung; Yun, Hyung-Joong; Lee, Jouhahn; Choi, Chel-Jong

    2014-11-01

    The current-voltage characteristics and the carrier-transport mechanism of the Er-silicide (ErSi1.7) Schottky contacts to strained-silicon-on-insulator (sSOI) and silicon-on-insulator (SOI) were investigated. Barrier heights of 0.74 eV and 0.82 eV were obtained for the sSOI and SOI structures, respectively. The barrier height of the sSOI structure was observed to be lower than that of the SoI structure despite the formation of a Schottky contact using the same metal silicide. The sSOI structure exhibited better rectification and higher current level than the SOI structure, which could be associated with a reduction in the band gap of Si caused by strain. The generation-recombination mechanism was found to be dominant in the forward bias for both structures. Carrier generation along with the Poole-Frenkel mechanism dominated the reverse-biased current in the SOI structure. The saturation tendency of the reverse leakage current in the sSOI structure could be attributed to strain-induced defects at the interface in non-lattice-matched structures.

  17. Schottky barrier detection devices having a 4H-SiC n-type epitaxial layer

    Science.gov (United States)

    Mandal, Krishna C.; Terry, J. Russell

    2016-12-06

    A detection device, along with methods of its manufacture and use, is provided. The detection device can include: a SiC substrate defining a substrate surface cut from planar to about 12.degree.; a buffer epitaxial layer on the substrate surface; a n-type epitaxial layer on the buffer epitaxial layer; and a top contact on the n-type epitaxial layer. The buffer epitaxial layer can include a n-type 4H--SiC epitaxial layer doped at a concentration of about 1.times.10.sup.15 cm.sup.-3 to about 5.times.10.sup.18 cm.sup.-3 with nitrogen, boron, aluminum, or a mixture thereof. The n-type epitaxial layer can include a n-type 4H--SiC epitaxial layer doped at a concentration of about 1.times.10.sup.13 cm.sup.-3 to about 5.times.10.sup.15 cm.sup.-3 with nitrogen. The top contact can have a thickness of about 8 nm to about 15 nm.

  18. The Surface Structure, Scattering Losses and Schottky Barrier Model of III-V Compound Semiconductors.

    Science.gov (United States)

    1982-12-21

    CEN,CS2,CS4,CDS2,CDS4,CNi2 COMPLEX CN3 ,CN4 ,CN , CBETA, CMPLX, CATAN PRI-3. 14159625 CN1-CMPLX(3 .4700,-a .0005) CN2-1 .0 CN3-3.42 CN4-3.4 CN5-3.42 RK...CN1**2-CN5**2) *R**2...**2) CDS3-(- ) *CKX*CN3**2/CN1**2/CS3 CDS5-(-1) *CK*CN45**2/CNl**2/CS5 CFEMCKX=*A-P*PHI+ CATAN (-GUS 3) + CATAN (-GUS 5...0.002) 45 CS2-CSQRT(C(CN1**2-CGN2**2) *RJ**2...=**2) CS4-CSQRT ((CN1**2-CN4**2) *R**2-CCY**2) CDS2-(-.) *CKY/CS2 CDS4u(.)*K/CS4 CFKY-CX!*B-Q*PHI+ CATAN

  19. Photoelectrochemical etching of ZnSe and nonuniform charge flow in Schottky barriers

    Science.gov (United States)

    Tenne, R.; Flaisher, H.; Triboulet, R.

    1984-05-01

    Photoelectrochemical etching of ZnSe, similar to that which was employed for cadmium chalcogenides, is found to decrease electron-hole recombinations upon photoexcitation considerably and to change the morphology of the semiconductor surface. Thus the photocurrent of a single-crystal ZnSe electrode in various electrolytes increases considerably (up to 100%) after such treatment. A unique morphology consisting of a dense pattern (109 cm-2) of etch pits is revealed after photoetching. This pattern is believed to reflect the dopant distribution close to the surface. Onset potential measurements show an anodic shift in the flat-band potential after photoetching which may arise from reduced pinning of the Fermi level associated with elimination of surface states. These measurements also indicate that the average dopant density close to the semiconductor surface is reduced after photoetching in accordance with our model of nonuniform hole flow in the space-charge region.

  20. A 200 GHz tripler using a single barrier varactor

    Science.gov (United States)

    Choudhury, Debabani; Frerking, Margaret A.; Batelaan, Paul D.

    1993-01-01

    The GaAs Schottky varactor diode is the nonlinear device most commonly used for submillimeter wave harmonic generation. Output power adequate to serve as a local oscillator source for SIS tunnel junctions has been demonstrated with whisker-contacted GaAs Schottky varactor multipliers in waveguide mounts up to about 800 GHz. In this paper, we present results for a tripler to 200 GHz using a new multiplier device, the single barrier varactor (SBV). This new varactor has potential advantages such as stronger nonlinearities or special symmetry, which make it attractive for submillimeter wave frequency multiplication. The performance of a tripler using a SBV over a output frequency range from 186 to 207 GHz has been measured in a crossed waveguide mount. The theoretical performance of the device has been calculated using large signal analysis. A comparison of theoretical and measured results and a discussion of various losses in the mount and the varactor have also been presented.

  1. A 200 GHz tripler using single barrier varactor

    Science.gov (United States)

    Choudhury, Debabani; Frerking, Margaret A.; Batelaan, Paul D.

    1992-01-01

    The GaAs Schottky varactor diode is the nonlinear device most commonly used for submillimeter wave harmonic generation. Output power adequate to serve as a local oscillator source for SIS tunnel junctions has been demonstrated with whisker-contacted GaAs Schottky varactor multipliers in waveguide mounts up to about 800 GHz. In this paper, we present results for a tripler to 200 GHz using a new multiplier device, the single barrier varactor (SBV). This new varactor has a potential advantages such as stronger nonlinearities or special symmetry, which make it attractive for submillimeter wave frequency multiplication. The performance of a tripler using a SBV over a output frequency range from 186 to 207 GHz has been measured in a crossed waveguide mount. The theoretical performance of the device has been calculated using large signal analysis. A comparison of theoretical and measured results and a discussion of various losses in the mount and the varactor have also been presented.

  2. Neutron irradiation effects on gallium nitride-based Schottky diodes

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chung-Han; Katz, Evan J.; Zhang, Zhichun [Department of Electrical and Computer Engineering, The Ohio State University, Columbus Ohio 43210 (United States); Qiu, Jie; Cao, Lei [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Mishra, Umesh K. [Departments of Electrical and Computer Engineering and Materials Science and Engineering, University of California, Santa Barbara, California 93106 (United States); Brillson, Leonard J. [Department of Electrical and Computer Engineering, The Ohio State University, Columbus Ohio 43210 (United States); Department of Physics and Center for Materials Research, The Ohio State University, Columbus, Ohio 43210 (United States)

    2013-10-14

    Depth-resolved cathodoluminescence spectroscopy (DRCLS), time-resolved surface photovoltage spectroscopy, X-ray photoemission spectroscopy (XPS), and current-voltage measurements together show that fast versus thermal neutrons differ strongly in their electronic and morphological effects on metal-GaN Schottky diodes. Fast and thermal neutrons introduce GaN displacement damage and native point defects, while thermal neutrons also drive metallurgical reactions at metal/GaN interfaces. Defect densities exhibit a threshold neutron fluence below which thermal neutrons preferentially heal versus create new native point defects. Scanning XPS and DRCLS reveal strong fluence- and metal-dependent electronic and chemical changes near the free surface and metal interfaces that impact diode properties.

  3. Graphene-Based Reversible Nano-Switch/Sensor Schottky Diode

    Science.gov (United States)

    Miranda, Felix A.; Meador, Michael A.; Theofylaktos, Onoufrios; Pinto, Nicholas J.; Mueller, Carl H.; Santos-Perez, Javier

    2010-01-01

    This proof-of-concept device consists of a thin film of graphene deposited on an electrodized doped silicon wafer. The graphene film acts as a conductive path between a gold electrode deposited on top of a silicon dioxide layer and the reversible side of the silicon wafer, so as to form a Schottky diode. By virtue of the two-dimensional nature of graphene, this device has extreme sensitivity to different gaseous species, thereby serving as a building block for a volatile species sensor, with the attribute of having reversibility properties. That is, the sensor cycles between active and passive sensing states in response to the presence or absence of the gaseous species.

  4. The properties of transparent TiO2 films for Schottky photodetector

    Directory of Open Access Journals (Sweden)

    Sung-Ho Park

    2017-08-01

    Full Text Available In this data, the properties of transparent TiO2 film for Schottky photodetector are presented for the research article, entitled as “High-performing transparent photodetectors based on Schottky contacts” (Patel et al., 2017 [1]. The transparent photoelectric device was demonstrated by using various Schottky metals, such as Cu, Mo and Ni. This article mainly shows the optical transmittance of the Ni-transparent Schottky photodetector, analyzed by the energy dispersive spectroscopy and interfacial TEM images for transparency to observe the interface between NiO and TiO2 film. The observation and analyses clearly show that no pinhole formation in the TiO2 film by Ni diffusion. The rapid thermal process is an effective way to form the quality TiO2 film formation without degradation, such as pinholes (Qiu et al., 2015 [2]. This thermal process may apply to form functional metal oxide layers for solar cells and photodetectors.

  5. Tension assisted metal transfer of graphene for Schottky diodes onto wafer scale substrates.

    Science.gov (United States)

    Lee, Jooho; Lee, Su Chan; Kim, Yongsung; Heo, Jinseong; Lee, Kiyoung; Lee, Dongwook; Kim, Jaekwan; Lee, Sunghee; Lee, Chang Seung; Nam, Min Sik; Jun, Seong Chan

    2016-02-19

    We developed an effective graphene transfer method for graphene/silicon Schottky diodes on a wafer as large as 6 inches. Graphene grown on a large scale substrate was passivated and sealed with a gold layer, protecting graphene from any possible contaminant and keeping good electrical contact. The Au/graphene was transferred by the tension-assisted transfer process without polymer residues. The gold film itself was used directly as the electrodes of a Schottky diode. We demonstrated wafer-scale integration of graphene/silicon Schottky diode using the proposed transfer process. The transmission electron microscopy analysis and relatively low ideality factor of the diodes indicated fewer defects on the interface than those obtained using the conventional poly(methyl methacrylate)-assisted transfer method. We further demonstrated gas sensors as an application of graphene Schottky diodes.

  6. Tension assisted metal transfer of graphene for Schottky diodes onto wafer scale substrates

    Science.gov (United States)

    Lee, Jooho; Lee, Su Chan; Kim, Yongsung; Heo, Jinseong; Lee, Kiyoung; Lee, Dongwook; Kim, Jaekwan; Lee, Sunghee; Lee, Chang Seung; Nam, Min Sik; Jun, Seong Chan

    2016-02-01

    We developed an effective graphene transfer method for graphene/silicon Schottky diodes on a wafer as large as 6 inches. Graphene grown on a large scale substrate was passivated and sealed with a gold layer, protecting graphene from any possible contaminant and keeping good electrical contact. The Au/graphene was transferred by the tension-assisted transfer process without polymer residues. The gold film itself was used directly as the electrodes of a Schottky diode. We demonstrated wafer-scale integration of graphene/silicon Schottky diode using the proposed transfer process. The transmission electron microscopy analysis and relatively low ideality factor of the diodes indicated fewer defects on the interface than those obtained using the conventional poly(methyl methacrylate)-assisted transfer method. We further demonstrated gas sensors as an application of graphene Schottky diodes.

  7. SiC merged p-n/Schottky rectifiers for high voltage applications

    Energy Technology Data Exchange (ETDEWEB)

    Held, R.; Kaminski, N.; Niemann, E. [Daimler-Benz AG, Frankfurt am Main (Germany). Forschung und Technik

    1998-08-01

    A method of reducing reverse currents and increasing breakdown voltages without inducing negative effects on switching behavior in silicon carbide Schottky diodes is proved successfully. Implantation of p-regions in the surface of the n-drift region below the Schottky metal form face to face p-n junctions which screen the Schottky contact from high electrical fields. This results in a reduction of the reverse current and an increase of the breakdown voltage to the limit of a `pure` SiC p-n diode. It is shown, that in contrast to silicon based devices, SiC merged p-n/Schottky (MPS) rectifier preserve their excellent unipolar switching behavior. (orig.) 5 refs.

  8. Simulation of a perfect CVD diamond Schottky diode steep forward current–voltage characteristic

    Energy Technology Data Exchange (ETDEWEB)

    Kukushkin, V.A., E-mail: vakuk@appl.sci-nnov.ru [Institute of Applied Physics of the Russian Academy of Science, 46 Ulyanov St., 603950 Nizhny Novgorod (Russian Federation); Nizhny Novgorod State University named after N.I. Lobachevsky, 23 Gagarin pr., 603950 Nizhny Novgorod (Russian Federation)

    2016-10-01

    The kinetic equation approach to the simulation of the perfect CVD diamond Schottky diode current–voltage characteristic is considered. In result it is shown that the latter has a significantly steeper forward branch than that of perfect devices of such a type on usual semiconductors. It means that CVD diamond-based Schottky diodes have an important potential advantage over analogous devices on conventional materials.

  9. Simulation of a perfect CVD diamond Schottky diode steep forward current-voltage characteristic

    Science.gov (United States)

    Kukushkin, V. A.

    2016-10-01

    The kinetic equation approach to the simulation of the perfect CVD diamond Schottky diode current-voltage characteristic is considered. In result it is shown that the latter has a significantly steeper forward branch than that of perfect devices of such a type on usual semiconductors. It means that CVD diamond-based Schottky diodes have an important potential advantage over analogous devices on conventional materials.

  10. Nanocrystalline Zn{sub 1−x}Mn{sub x}O thin film based transparent Schottky diodes

    Energy Technology Data Exchange (ETDEWEB)

    Gayen, R.N. [Department of Physics, Presidency University, Kolkata 700073 (India); Paul, R., E-mail: rajiv2008juniv@gmail.com [Birck Nanotechnology Center, Purdue University, IN 47907 (United States)

    2016-04-30

    Highly transparent and nanocrystalline Zn{sub 1−x}Mn{sub x}O (x = 0, 0.008, 0.017, 0.046) thin films have been synthesized by sol–gel spin coating technique on glass and SnO{sub 2} coated glass substrates. The microstructural and compositional analyses confirm the incorporation of Mn in hexagonal ZnO lattice without affecting its structure. Zn{sub 1−x}Mn{sub x}O thin films are highly transparent in the visible region of electromagnetic spectrum. The optical band gap, estimated from the transmittance spectra, decreases from 3.32 to 3.21 eV with the increase in Mn content in ZnO films. Photoluminescence study reveals that Mn introduces more defects in ZnO suppressing the excitonic recombination by the defect center (oxygen vacancy) induced recombination. The non-linear current–voltage characteristics at room temperature reveal Schottky barrier junction formation of Zn{sub 1−x}Mn{sub x}O films with Ag. The diode parameters, extracted from the thermionic emission model, vary with Mn incorporation in ZnO. Both the ideality factor and potential barrier height decrease from 6.5 and 0.63 for pure ZnO to 4.7 and 0.54 respectively, for Zn{sub 0.954}Mn{sub 0.046}O film. The series resistance that arises from the defect distributions at the interface and effects the charge transport through the junction, also decreases for higher percentage of Mn in Zn{sub 1−x}Mn{sub x}O thin films. - Highlights: • Mn doped transparent ZnO thin film synthesis using sol–gel spin coating • Particle size and optical band-gap decreases with increasing Mn doping. • Absence of any secondary phase upto 4.6 at.% of Mn which substitutes Zn sites in ZnO lattice • Interesting Schottky diode characteristics with Ag contact • Ideality factor and barrier height decreases with increasing Mn content.

  11. Effects of Pt diffusion barrier layer on the interface reaction and electric properties of PZT film/Si ( 111 ) sample

    Institute of Scientific and Technical Information of China (English)

    ZHU, Yong-Fa(朱永法); CAO, Li-Li(曹立礼); YAN, Pei-Yu(阎培渝); LI, Long-Tu(李龙土); YI, Tao(易涛)

    2000-01-01

    The effects of the Pt diffusion barrier layer on the interface diffusion and reaction, crystallization, dielectric and ferroelectric properties of the PZT/Si(111) sample have been studied using XPS, AES and XRD techniques. The results indicate that the Pt diffusion barrier layer between the PZT layer and the Si substrate prohibits the formation of TiCx, TiSix and SiO2 species in the PZT layer. The Pt barrier layer also completely interrupts the diffusion of Si from the Si substrate into the PZT layer and impedes the diffusion of oxygen from air to the Si substrate greatly. Although the Pt layer can not prevent completely the diffusion and reaction between oxygen and silicon, it can prevent the formation of a stable SiO2 interface layer on the interface of PZT/Si. The Pt layer reacts with silicon to form PtSix species on the interface of Pt/Si, which can intensify the chemical binding strength between the Pt layer and the Si substrate. To play a good role as a diffusion barrier layer, the Pt barrier layer must be not thinner than 140 nm. The existence of the Pt layer not only promotes the crystallization of PZT layer to form a perovskite phase but also improves dielectric and ferroelectric performances of the PZT layer.

  12. Oxygen modulation of flexible PbS/Pb Schottky junction PEC cells with improved photoelectric performance

    Science.gov (United States)

    Wang, Peng; Fan, Libo; Guo, Qiuquan; Shi, Hongcai; Wang, Liwen; Liu, Yujian; Li, Ming; Zhang, Chunli; Yang, Jun; Zheng, Zhi

    2016-09-01

    Flexible photoelectric devices are emerging as a new class of photovoltaic cells. In this study, lead (Pb) foil was used as a flexible substrate to grow in situ lead sulfide (PbS) film with good uniformity and adhesion by a solvothermal elemental direct reaction, resulting in a PbS/Pb Schottky junction formed naturally between the PbS film and underlying Pb foil. We found that the photocurrent response of the photoelectrochemical (PEC) cell was greatly improved through a facile oxygen (O2)-modulation-based post-processing technique. O2 could decompose the organic residue and oxidize the Pb at the interface between the PbS film and Pb foils. Different characterization techniques, including thermogravimetric analysis, differential scanning calorimetry, x-ray diffraction, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, the change in transient photocurrent density (J p) with time (t), dark current-voltage (I-V) and absorption spectra were applied to get a full understanding of the O2 modulation effect. The oxidization treatment of the PbS film could regulate the flow of charge carriers to reduce their recombination, leading to photoresponse enhancement for the PEC cells. In particular, the process could modulate the tunneling current and interface states to optimize dark I-V characteristics. In addition, the magnitude of the barrier height can be tuned by O2 modulation, which was explained by theoretical analysis and calculation. We also demonstrated that the in situ formed PbS film has outstanding adhesion on the flexible Pb substrate. Our film synthesis method and post O2-modulation design as well as the corresponding device assembly may provide a novel perspective to the flexible PCE-cell-related research.

  13. Analysis of Schottky Contact Formation in Coplanar Au/ZnO/Al Nanogap Radio Frequency Diodes Processed from Solution at Low Temperature.

    Science.gov (United States)

    Semple, James; Rossbauer, Stephan; Anthopoulos, Thomas D

    2016-09-01

    Much work has been carried out in recent years in fabricating and studying the Schottky contact formed between various metals and the n-type wide bandgap semiconductor zinc oxide (ZnO). In spite of significant progress, reliable formation of such technologically interesting contacts remains a challenge. Here, we report on solution-processed ZnO Schottky diodes based on a coplanar Al/ZnO/Au nanogap architecture and study the nature of the rectifying contact formed at the ZnO/Au interface. Resultant diodes exhibit excellent operating characteristics, including low-operating voltages (±2.5 V) and exceptionally high current rectification ratios of >10(6) that can be independently tuned via scaling of the nanogap's width. The barrier height for electron injection responsible for the rectifying behavior is studied using current-voltage-temperature and capacitance-voltage measurements (C-V) yielding values in the range of 0.54-0.89 eV. C-V measurements also show that electron traps present at the Au/ZnO interface appear to become less significant at higher frequencies, hence making the diodes particularly attractive for high-frequency applications. Finally, an alternative method for calculating the Richardson constant is presented yielding a value of 38.9 A cm(-2) K(-2), which is close to the theoretically predicted value of 32 A cm(-2) K(-2). The implications of the obtained results for the use of these coplanar Schottky diodes in radio frequency applications is discussed.

  14. States of the Schottky defect in uranium dioxide and other fluorite type crystals: Molecular dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Kovalenko, M.A., E-mail: akm_max@mail.ru; Kupryazhkin, A. Ya, E-mail: a.ya.kupryazhkin@urfu.ru

    2015-10-05

    Highlights: • We derived the degree of vacancy association in Schottky defects from temperature. • At high temperatures cation vacancy forms complexes with anion vacancies. • Point defects model in the presence of complexes was considered. • The presence of anion vacancies around cation vacancy lowers its migration energy. • The formation of nanovoids at high cation vacancy concentrations was shown. - Abstract: Mass transfer processes in fluorite-type systems are determined by the diffusion of cations via vacancies from Schottky defects. To predict diffusion coefficients of cations and other parameters based on it the Lidiard and Matzke approximation of the point defects model, namely the assumption of isolated vacancies, is widely used. States of the Schottky defect were studied with the high-speed molecular dynamics method in a wide temperature range, with six different interaction potentials. Schottky vacancies were dynamically detected during the simulation. It is shown that contrary to the Lidiard and Matzke model, the Schottky cation vacancy is always associated with anion vacancies. The degree of the Schottky defect association depends on the temperature, at high temperatures near the cation vacancy two or more anion vacancies are located. It is shown that the calculated formation energy of Schottky defects in the form of the trivacancy (5.8–7.4) eV for all potentials are close to the experimental value (6–7) eV, in contrast to the formation energy of Schottky defects in the form of isolated vacancies that exceeds 10 eV. Point defects model of the simulated system in the presence of an artificially created Schottky defect was constructed and compared with calculation results. According to our study the point defects model is applicable only at low temperatures less than half of the melting temperature. It is shown that the presence of anion vacancies near the cation vacancy reduces the migration energy of cations. However, for systems with

  15. Millimeter and Submillimeter-Wave Integrated Horn Antenna Schottky Receivers.

    Science.gov (United States)

    Ali-Ahmad, Walid Youssef

    1993-01-01

    Fundamental Schottky-diode mixers are currently used in most millimeter-wave receivers above 100GHz. The mixers use either a whisker-contacted diode or a planar Schottky diode suspended in a machined waveguide with an appropriate RF matching network. However, waveguide mounts are very expensive to machine for frequencies above 200GHz. Also, the whisker-contacted structure is not compatible with integrated mixers which represent the leading technology used for millimeter- and submillimeter-wave applications such as plasma diagnostics imaging arrays, radiometers, and anti-collision radars. In this work, a novel quasi-integrated horn antenna has been used for the receiver antenna. This antenna has a high gain and a high Gaussian coupling efficiency (97%), similar to machined scalar feed horns, but with the advantage of being easily fabricated up to at least 1.5THz. The quasi-integrated horn antenna is based on the integrated horn antenna structure. The integrated horn antenna consists of a pyramidal cavity with a 70^circ flare angle etched anisotropically in silicon. The cavity focuses the incoming energy on dipole-probe suspended on a membrane inside the horn. The integrated horn antenna does not suffer from dielectric losses or substrate mode losses since the feeding dipole antenna is integrated on a very thin dielectric layer. The mixer circuit, along with the feed dipole, are both integrated on the membrane wafer. The mixer diode is the University of Virginia surface channel planar diode which has a low parasitic capacitance. The diode is epoxied directly at the dipole apex without the need for an RF matching network, and with no mixer tuning required. At 92GHz,the DSB antenna-mixer conversion loss and noise temperature are 5.5dB and 770K, respectively. This represents the best reported results to this date for a quasi-optical mixer with a planar diode, at room temperature. At 335GHz, the DSB antenna-mixer noise temperature is 1750K and it is within 1dB of the

  16. Performance of the resonant Schottky pickup at CSRe

    CERN Document Server

    Wua, J X; Nolden, F.; Sanjari, M.S.; Hülsmann, P.; Caspers, F.; Zhao, T.C.; Li, M.; Zhang, J.Z.; Li, J.; Zhang, Y.; Zhu, G.Y.; Zhang, S.H.; Ma, X.W.; Xu, H.S.; Yang, J.C.; Xia, J.W.; Mao, R.S.; Petri, P.

    2013-01-01

    For a bunched beam, the signals on pickups are coherent, providing a signal power proportional to the square of the number of particles. For a coasting beam the individual particle signals have a random phase; therefore, the overall signal is proportional to the particle number N. As a consequence, Schottky signals are often relatively weak and have to compete with many noise sources. For a small number of particles, the S/N is always a problem. To achieve a high signal-to-noise ratio and better temporal resolution, which could yield important physical information about fast processes, a resonant pickup was developed at GSI (Nolden et al., 2011 [1]), and a similar device is now installed in the CSRe [2] at IMP. This device will be used for nuclear mass and lifetime measurement, as well as other uses. The final goal of the pickup is to detect single particles. In Dec 2012, we performed an experiment with a 112Sn50+ beam with an energy of 253 MeV/u, and the single particle sensitivity of the pickup was successf...

  17. A Strained Silicon Cold Electron Bolometer using Schottky Contacts

    CERN Document Server

    Brien, T L R; Barry, P S; Dunscombe, C; Leadley, D R; Morozov, D V; Myronov, M; Parker, E H C; Prest, M J; Sudiwala, R V; Whall, T E; Mauskopf, P D

    2014-01-01

    We describe optical characterisation of a Strained Silicon Cold Electron Bolometer (CEB), operating on a $350~\\mathrm{mK}$ stage, designed for absorption of millimetre-wave radiation. The silicon Cold Electron Bolometer utilises Schottky contacts between a superconductor and an n++ doped silicon island to detect changes in the temperature of the charge carriers in the silicon, due to variations in absorbed radiation. By using strained silicon as the absorber, we decrease the electron-phonon coupling in the device and increase the responsivity to incoming power. The strained silicon absorber is coupled to a planar aluminium twin-slot antenna designed to couple to $160~\\mathrm{GHz}$ and that serves as the superconducting contacts. From the measured optical responsivity and spectral response, we calculate a maximum optical efficiency of $50~\\%$ for radiation coupled into the device by the planar antenna and an overall noise equivalent power (NEP), referred to absorbed optical power, of $1.1 \\times 10^{-16}~\\math...

  18. Alternative current source based Schottky contact with additional electric field

    Science.gov (United States)

    Mamedov, R. K.; Aslanova, A. R.

    2017-07-01

    Additional electric field (AEF) in the Schottky contacts (SC) that covered the peripheral contact region wide and the complete contact region narrow (as TMBS diode) SC. Under the influence of AEF is a redistribution of free electrons produced at certain temperatures of the semiconductor, and is formed the space charge region (SCR). As a result of the superposition of the electric fields SCR and AEF occurs the resulting electric field (REF). The REF is distributed along a straight line perpendicular to the contact surface, so that its intensity (and potential) has a minimum value on the metal surface and the maximum value at a great distance from the metal surface deep into the SCR. Under the influence of AEF as a sided force the metal becomes negative pole and semiconductor - positive pole, therefore, SC with AEF becomes an alternative current source (ACS). The Ni-nSi SC with different diameters (20-1000 μm) under the influence of the AEF as sided force have become ACS with electromotive force in the order of 0.1-1.0 mV, which are generated the electric current in the range of 10-9-10-7 A, flowing through the external resistance 1000 Ohm.

  19. Investigation of nanostructured Pd-Ag/n-ZnO thin film based Schottky junction for methane sensing

    Science.gov (United States)

    Roy, S.; Das, S.; Sarkar, C. K.

    2016-07-01

    Undoped nanocrystalline n-type ZnO thin film was deposited by chemical deposition technique on a thermally oxidized p-Si (~5 Ω cm resistivity and orientation) substrate. Formation of stable zinc oxide thin film was confirmed by two-dimensional X-Ray Diffraction (XRD) and EDX analysis. The average crystallite size of the ZnO sample was evaluated as ~50 nm. The surface was characterized by Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM) that confirm the formation of nanocrystalline (grain size ~50 nm) ZnO thin film with surface roughness of ~100 nm. Good conversion of precursor into ZnO thin film in the chemical deposition method was evident by Fourier Transform Infrared Spectroscopy (FTIR). A small peak at 479 cm-1was observed in the FTIR spectrum confirming the formation of quartzite structure of the ZnO. The band gap (~3.44 eV) of the material was calculated from the optical absorption spectroscopy. To prepare Pd-Ag/n-ZnO Schottky junction, Pd-Ag contacts were taken by electron beam evaporation method. I-V characteristics of the junction were studied at different temperatures in inert and reducing ambient (N2 and N2 + CH4) with turn on voltage of around 0.2 V. The parameters like ideality factor ( η), saturation current ( I 0), series resistance ( Rs), and barrier height ( Φ BO) of the junction were calculated in the temperature range 50-200 °C in N2 as well as in 1 % CH4 + N2 ambient. It was observed that the ideality factor decreases in the temperature range 50-200 °C ( η = 12.34 at 50 °C and η = 1.52 at 200 °C) in N2 ambient and η = 1.18 in N2 +CH4 ambient at 200 °C. Schottky Barrier Height ( Φ BO) of the Pd-Ag/n-ZnO junction was found to increase with temperature. A close observation of Pd-Ag/n-ZnO junction in the presence of methane was performed to appreciate its application as methane sensor. The sensing mechanism was illustrated by a simplified energy band diagram.

  20. Low-Resistance Spin Injection into Silicon Using Graphene Tunnel Barriers

    Science.gov (United States)

    2012-11-01

    generate high local magnetoresistance. Reducing the resistance–area product also has a positive effect on the electrical properties of the spin device, as...injection through an Fe/ AlGaAs Schottky barrier. Appl. Phys. Lett. 82, 4092–4094 (2003). 14. Motsnyi, V. F. et al. Electrical spin injection in a ferromagnet...37. Sze, S. M. Physics of Semiconductor Devices 29 (Wiley, 1981). 38. Dery, H., Cywinski, L. & Sham, L. J. Lateral diffusive spin transport in