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Photodiodes based on solid solutions in the GaSb–InAs system are for the first time applied to study the spectral characteristics of single and coupled whispering-gallery-mode (WGM) lasers emitting in a range of 2.2–2.3 μm. The capacity of photodiodes with a photosensitive area 2.0 mm in diameter is C = 520 pF at U = –2 V, which corresponds to a time constant of τ = 53 ns. It is shown that the parameters of the fabricated photodiodes make it possible to detect the emission of quantum-sized disc lasers at room temperature not using cryogenic cooling.

ZnS thin films have been successfully deposited with the same production parameters using thermionic vacuum arc technique on glass and silicon substrates. UV–Vis absorbance spectra and photoluminescence measurements were performed for the optical characterization of ZnS/glass thin film and ZnS/p-Si heterojunction device, respectively. The optical band gap is found approximately 3.78 eV. Further, electrical parameters of the device were determined for the current-voltage (I-V) measurements in dark and under illumination conditions. The open-circuit voltage and the short-circuit current values have been obtained related to illumination I-V measurements. Also, we have utilized photocurrent measurements to investigate the wavelength dependent to photosensitivity of the ZnS/p-Si heterojunction device.

ZnS/p-Si heterojunction diode has been successfully fabricated by depositing the ZnS thin films on p-type Si substrates using thermionic vacuum arc technique (TVA). The structural analysis was performed with X-ray diffraction (XRD) and Atomic force microscopy (AFM). The results revealed that ZnS thin film demonstrates nano-crystalline behavior with very smooth and homogeneous surface properties. The type was determined as n-type and the carrier concentration was found approximately 3.1 +/- 10(17) cm(-3) of the ZnS thin film by means of Hall Effect measurement. The dark current-voltage (I-V) and the capacitance- voltage (C-V) measurements with different frequencies were performed to determine the characteristics of the ZnS/p-Si heterojunction diode at room temperature. I-V results show that the diode has a good rectifying characteristic with excellent rectification ratio. The electrical parameters of the diode have been obtained by using current transport mechanism. It was found that the barrier height calculated from dark I-V measurements is in good agreement with the value obtained from C-V measurements at a frequency of 1.5 MHz. The series resistance and the built in potential of the fabricated diode were calculated as 3.6 k Omega and 0.7 V using Cheung and Cheung's equation and C-V measurement, respectively. The low cost and effective film production method were utilized to fabrication of heterojunction diode and to investigate characteristics.

The Au88Ge12 alloy/n-type GaAs(100)/Graphene Oxide (GO)/Au Schottky barrier diode has been fabricated. GO has been prepared by Hummers method and deposited on the GaAs substrate by spraying method. Schottky diode was investigated under dark and light intensity by the current-voltage (I-V) characteristics of the heterojunction. Thermionic current mechanism above the barrier has been detected by current-voltage measurements. It was found that the barrier height increases and the ideality factor decreases with light intensity. The obtained results indicate that GaAs/GO diode can be used as a photosensor in optoelectronic applications. Also, Schottky diode has been measured by capacitance-voltage (C-V) and conductance-voltage (G-V) in the frequency range from 10 kHz to 1 MHz at room temperature.

Photodiodes developed in the GaSb-InAs system were first used for investigation the spectral characteristics of single and coupled disk lasers emitting on whispering gallery modes at 2.2–2.3 µm. The capacity of the photodiodes with a diameter of photosensitive area of 2.0 mm was C=520 pF at U=−2 V, which corresponds to a time constant of tau=53 ns. It is shown that the parameters of the developed photodiodes make it possible to detect the emission of quantum-sized disk lasers at room temperature and not to use cryogenic cooling.

s Poly (ethylene glycol dimethacrylate-1-vinyl-1H-pyrrole-2-carboxylic acid)/carbon nanotube, single-walled)/n-Si ([P(EGDMA-VPCA)-SWCNT]/n-Si) photodiode structures was fabricated by using surface polymerization method. While electrical properties were measured at different temperatures, optical properties were measured at room temperatures. Dark and light current characteristics were investigated. Spectral photoresponse measurements of the structure were realized at room temperature. They showed that the fabricated structure exhibited rectification behavior, which makes it a good nominee for optoelectronic implementation area.

Bu çalışma, 14-19 Ekim 2015 tarihlerinde Kemer[Türkiye]’düzenlenen 2. International Conference on Computational and Experimental Science and Engineering (ICCESEN) Kongresi‘nde bildiri olarak sunulmuştur. Poly(ethylene glycol dimethacrylate-co-1-vinyl-1,2,4-triazole/carbon nanotube, single-walled)/n-GaAs ([P(EGDMA-VTAZ)-CNSW]/n-GaAs) diode was fabricated by using surface polymerization method. Electrical properties were carried out at several temperatures. Dark current mechanisms were investigated by using current-voltage (I-V) measurements. It was shown that the fabricated structure exhibited rectification behaviour that makes it a good candidate for electronic device applications.

In this paper, electrical characterization of low bandgap GaInAsSb based thermophotovoltaic (TPV) diodes were investigated, as well as the temperature dependence of photovoltaic parameters such as short circuit current (Isc) and open circuit voltage (Voc). Investigation of the dark current mechanisms of the structure was carried out at several temperatures. The effect of light intensity on current-voltage characteristics was also investigated.

The photovoltaic characteristics of a type II staggered heterojunction in the GaSb/GaInAsSb/GaAlAsSb system were studied. The dark current and R 0 A product were investigated at different temperatures. The current–voltage characteristics of n -GaSb/ n -GaInAsSb/ p -GaAlAsSb heterostructures were investigated at room temperature in the photovoltaic mode under illumination by light with wavelength of 0.95–1.0 μm and different intensities. A short-circuit current and an open circuit voltage as a function of intensity of incident light in photovoltaic mode were studied.

GaInAsSb/GaSb/GaAlAsSb double heterostructures are attractive for optoelectronic devices working in the 1.5 4.8 μm wavelength region. In this paper, the current mechanisms of liquid phase epitaxy grown GaInAsSb based double heterostructures with 100 μm diameter were investigated in the temperature range 77 350 K. It was found that di usion current dominates at the high temperature (> 240 K) and small forward bias region, while generation-recombination current dominates at intermediate temperatures (242 171 K). At low temperature region (< 171 K), the tunneling mechanism of the current ow dominates in both forward and reverse biases.

Bu çalışma, 4-8 Şubat 2010 tarihlerinde İstanbul[Türkiye]'da düzenlenen 2. World Conference on Educational Sciences (WCES-2010)'da bildiri olarak sunulmuştur. The paper describes liquid phase epitaxial growth and characterization of the GaSb- and InAs-related materials for the photodiodes and thermophotovoltaic applications. It was shown that doping of the melt with holmium results in obtaining the high purity GaInAsSb and InAs layers. The passivation with the 1 M Na2S aqueous solution makes it possible to prepare flat growth surfaces of GaSb(1 0 0) and InAs(1 0 0) substrates after annealing. A reproducible technique has been developed for fabrication of the high-efficiency GaInAsSb/GaAlAsSb and InAs/InAsSbP photodiodes with the long-wavelength photosensitivity edge of 2.4 and 3.8 mu m, respectively. Room temperature detectivity in the spectral peak reaches D* = (0.8-1.0) x 10(11) W-1 cm Hz(1/2) for the GaInAsSb/GaAlAsSb photodiodes and D* = (3.0-5.0) x 109 W-1 cm Hz(1/2) for the InAs/InAsSbP devices. We have adapted the technology for thermophotovoltaic cells operating at an emitter temperature of 1000-1700 degrees

The electrical end optical characteristics of a type II double heterojunction (DH) in the GaSb/GaInAsSb/GaAlAsSb system with staggered band alignment were studied. An analysis of the photodiodes performance through the investigation into electrical and optical characteristics was carried out. The dark current mechanisms in the heterostructures were investigated at several temperatures. The experimental results show that at the low temperature region, the tunneling mechanism of the current flow dominates in both forward and reverse biases. At high temperatures region and in the range of voltage from 0.1 V to 1 V, the reverse current was defined by generation of carriers in the depletion region. Have been estimated the temperature coefficient of the shift of the long-wavelength edge of the spectral sensitivity at half-maximum as Delta lambda/Delta T = 1.6 nm/K. Quantum efficiency of 0.6-0.7 for the investigated photodiodes was reached without any antireflection coating. For GaSb/GaInAsSb/GaAlAsSb TPV cells, the internal quantum efficiency of 90% was achieved at wavelengths between 1.2 and 1.6 mu m. (C) 2010 Elsevier B.V. All rights reserved. Russian Foundation for Basic Research (RFBR) (07-02-01359) Russian Foundation of Basic Research (RFBR) (09-08-91224)

Radio-frequency (HF) quasi-potential Φ in the field of the space charge region of contact of a metal–semiconductor is explored. At the frequency, ω, greater frequency plasma fluctuations ω0 HF quasi-potential is positive, but at frequencies ω < ω0 quasi-potential Ph is negative. VAC and Schottky barrier with provision for HF quasi-potential are calculated. It is shown that HF gives an essential contribution on EMF hot carriers when frequency of wave is less in electronic gas fluctuations in layer potential barrier.

We have studied the electrical characteristics of photodiodes based on p-GaSb/p-GaInAsSb/N-GaAlAsSb heterojunctions and investigated the mechanisms of current transfer in these heterostructures at various temperatures. A comparison of the theoretical results and experimental data showed that the tunneling charge transfer mechanism dominates at low temperatures (T < 150 K) under both forward and reverse bias conditions. The tunneling current becomes a determining factor at an electric field strength in the p-n junction of no less that 105 V/cm, which is related to a small bandgap width of the materials studied and low effective masses of electrons and holes.

The electrical characteristics of Cr / p – Si (100) Schottky barrier diodes have been measured in the temperature range of 100–300 K. The I-V analysis based on thermionic emission (TE) theory has revealed an abnormal decrease of apparent barrier height and increase of ideality factor at low temperature. The conventional Richardson plot exhibits non-linearity below 200 K with the linear portion corresponding to activation energy 0.304 eV and Richardson constant (A*) value of 5.41×10-3 Acm-2 K -2 is determined from the intercept at the ordinate of this experimental plot, which is much lower than the known value of 32 Acm-2 K -2 for p-type Si . It is demonstrated that these anomalies result due to the barrier height inhomogeneities prevailing at the metal-semiconductor interface. Hence, it has been concluded that the temperature dependence of the I-V characteristics of the Cr/p – Si Schottky barrier diode can be successfully explained on the basis of TE mechanism with a Gaussian distribution of the barrier heights. Furthermore, the value of the Richardson constant found is much closer than that obtained without considering the inhomogeneous barrier heights.

Current flow mechanisms have been studied for liquid phase epitaxy grown isotype heterostructures lattice-matched to GaSb substrates. The dark current mechanisms in the N-n isotype heterostructures were investigated in detail at several temperatures. It is shown that both the type II staggered and misaligned heterojunctions can behave as Schottky diodes and the dark current–voltage characteristics of this isotype hetero-structures were rectifying over the whole temperature range 90–300 K. These measurements establish that the reverse current in both (staggered and misaligned) investigated structures are determined mainly by tunneling mechanism. The theoretical relations for reverse dark current in staggered lineup isotype heterostructures have been developed.

Band diagrams and current-voltage and capacitance-voltage characteristics of isotype N +-GaSb/n0-GaInAsSb/N +-GaAlAsSb heterostructures have been studied. Dark-current flow mechanisms have been analyzed. It is shown that a staggered type-II heterojunction can behave as a Schottky diode and its current-voltage characteristics exhibit rectifying properties over the entire temperature range 90–300 K. The thermionic-emission current predominates at high temperatures and low voltages. This current is due to thermal excitation of electrons from GaInAsSb to GaSb over the barrier at the heterointerface. A comparison of the relevant theoretical and experimental data confirmed that the tunneling charge transport mechanism plays the key role at low temperatures under both forward and reverse biases.

The predominant failure modes in stamping of sheet metal parts (deep drawing and stretch forming) are wrinkling and fracture. In many cases these defects may be eliminated by appropriate control of the Blank Holding Force (BHF). This paper summarizes the results of a recent study on the formability of rectangular parts from aluminum alloy 2008-T4. Wrinkling and fracture limits have been determined and BHF control methods have been developed to eliminate defects, improve part quality, and increase the draw depth.

Köçkar, Hakan (Balikesir Author), In this paper we report the electrical characteristics of the Schottky diodes formed by surface polymerization of the Poly(ethylene glycol dimethanylate-n-vinyl imidazole)/Single Walled Carbon Nanotubes on n-Si The Single Walled Carbon Nanotubes were synthesized by CVD method. The main electrical properties of the Poly(ethylene glycol dimethanylate-n-vinyl imidazole)/Single Walled Carbon Nanotubes/n-Si have been investigated through the barrier heights, the ideality factors and the impurity density distribution, by using current-voltage and reverse bias capacitance voltage characteristics. Electrical measurements were carried out at room temperature. Poly(ethylene glycol dimethacrylate-n-vinyl imidazole)/Single Walled Carbon Nanotubes/n-Si Schottky diode current-voltage characteristics display low reverse-bias leakage currents and average barrier heights of 0.61 +/- 0.02 eV and 0.72 +/- 0.02 eV obtained from both current-voltage and capacitance-voltage measurements at room temperature, respectively.

The electrical end optical characteristics of InAs/InAs0.7Sb0.1P0.2 heterojunctions were studied. The dark current mechanisms in the heterostructures were investigated at several temperatures. The experimental results shows that, the low temperature region the tunneling mechanism of the current flow dominates in both, forward and reverse biases. At high temperatures region and in the range of voltage from 0.1 V to 1 V. the reverse current was defined by diffusion mechanism. Russian Foundation for Basic Research (RFBR) - 07-02-01359 / 09-08-91224

The Cr/n-GaAs/Cr and Ag/p-GaAs/Ag metal–semiconductor–metal (MSM) Schottky contacts have been fabricated by reactive radio frequency (RF) sputtering system. The current–voltage ðI—VÞ and capacitance–voltage ðC—VÞ characteristics of the devices have been investigated in the temperature range of 80–316 K for the back-to-back switched Schottky barrier contacts. These measurements establish that the room temperature barrier height determined from reverse branch of the current–voltage characteristics is close to the value obtained from capacitance–voltage measurements.

This paper briefly presents some important aspects of the GaSb‐based material growth, as well as the performance of photodiodes and TPV devices for the 0.9–2.55 μm spectral range. A reproducible technique has been developed for the production of high‐speed and high‐efficiency GaSb/GaInAsSb/GaAlAsSb photodiodes. The detectivity of the photodiodes, estimated from the measured noise level and monochromatic current sensitivity, in the spectral peak reaches D*(λmax, 1000, 1)=(0.8–1.0)×1011 W−1×cm×Hz1/2 at room temperature. Recently, we have adapted the technology for creating GaInAsSb (0.52–0.53 eV band gap) TPV devices. Based on the our results we believe a 0.5 eV band gap GaSb‐based TPV cell with an open‐circuit voltage well over 300 mV at current 2–3 A is a realistic near‐term goal.

The dependence of reverse-biased leakage current on both voltage and temperature for InP - In x Ga 1-x As y P 1-y DH (double heterostructures) has been analyzed. We find that at the whole of the temperature range and at a wide range of reverse bias voltages, the reverse current varies exponentially with applied voltage, indicating that the band-to-band tunneling current mechanism prevails. An agreement is obtained between theory and experimental results. The tunneling current becomes substantial at peak junction electric fields as low as 105 V/m due to the small direct energy gaps and small effective masses of the structures tested. The process of breakdown in the investigated structures was of the avalanche type. The impact ionization coefficients in In x Ga 1-x As y P 1-y have been experimentally determined for composition x=0.68.

Bu çalışma, 19-24 Haziran tarihlerinde Beaune[Fransa]'da düzenlenen 4. International Conference on New Developments in Photodetection'da bildiri olarak sunulmuştur. We have developed a zinc sulfide-silicon (ZnS-Si) isotype heterojunction avalanche photodiode (APD) structure that has high quantum efficiency and low excess noise factor for photons of wavelength in the region from 340 to 800 nm. The dependence of quantum efficiency, mean signal and its fluctuation on incident photons wavelength are calculated in a well-defined device geometry by a Single Particle Monte Carlo simulation technique. Based on this work, we offer a new APD structure for scintillation light detection.

Hamamatsu S8148 silicon avalanche photodiode (APD) working in proportional mode has been chosen as readout device for the PbWO4 crystals in the barrel of the CMS electromagnetic calorimeter (ECAL). High hadron fluences strongly affect the main parameters of both the scintillation crystals and the silicon detectors. In this work, we offer a new zinc sulfide–silicon (ZnS–Si) isotype heterojunction APD structure that is able to operate in high-radiation levels. A Monte Carlo simulation code has been performed in order to compare the Hamamatsu S8148 and the ZnS–Si APD structures for the photons emitting from PbWO4 crystal during 10 years of CMS operation. Based on this work, the performance of these two APD structures has been investigated.