Fifteenth International Conference on Correlation Optics
The defects structure, charge collection, and detection efficiency of the Ni(NiO)/p-CdTe/Au/Cu Sc... more The defects structure, charge collection, and detection efficiency of the Ni(NiO)/p-CdTe/Au/Cu Schottky-diode detector have been investigated. The spectroscopic properties of the obtained heterostructures have been studied experimentally and analyzed theoretically. The optimal reverse bias voltage for higher performance of the detectors under study was determined. The reasons of poor charge collection in the detectors and low detection efficiency of photons emitted by an 241Am (59.5 keV) radioisotope have been established and discussed. The techniques of increasing the functional parameters of Ni(NiO)/p-CdTe/Au/Cu Schottky diodes have the investigated and the optimal ways for improvement of the detector performance have been formulated.
Fifteenth International Conference on Correlation Optics
The defect structure of p-CdTe:Cl single crystals and MoOx/p-CdTe/MoOx heterostructures based on ... more The defect structure of p-CdTe:Cl single crystals and MoOx/p-CdTe/MoOx heterostructures based on them were investigated by high-resolution X-ray diffractometry methods. Different models of dislocation systems were applied, according to which the densities of dislocations were estimated from the Wilson-Hall plot. It is shown that the application of the MoOx layer significantly affects the density of dislocations and their influence on the electrical and spectroscopic properties of heterostructures is estimated
Abstract-The charge transport mechanism and spectrometric properties of the Х/-ray detectors, ... more Abstract-The charge transport mechanism and spectrometric properties of the Х/-ray detectors, fabricated by the deposition of molybdenum oxide thin films onto semi-insulating p-CdTe crystals were studied. The current transport processes in the Mo-MoO x /р-CdTe/MoO x-Mo structure are well described in the scope of the carriers generation in the space-charge region and the space charge limited current models. The life time of charge carriers, the energy of holes traps and density of discrete trapping centers were determined from the comparison of the experimental data and calculations. Spectrometric properties of Mo-MoO x /р-CdTe/MoO x-Mo structures were also investigated. It is shown that the investigated heterojunctions have demonstrated promising characteristics for practical application in X/radiation detector fabrication.
This chapter deals with (i) the charge transport mechanisms in X-and gamma-ray detectors both Ohm... more This chapter deals with (i) the charge transport mechanisms in X-and gamma-ray detectors both Ohmic and Schottky types based on CdTe and its alloys with an almost intrinsic conductivity (the peculiarities of the formation of self-compensated complexes due to the doping of Cd(Zn)Te crystals with elements of III or V groups (In, Cl) are taken into account); (ii) the reasons of insufficient energy resolution in the X-and gamma-ray spectra taken with the detectors under study; (iii) the quantitative model which describes the spectral distribution of the detection efficiency of Cd(Zn)Te crystals with Schottky diodes; (iv) a correlation between the concentration of uncompensated impurities in the Cd(Zn)Te crystals and collection efficiency of photogenerated charge carriers in the detectors with a Schottky contact; (v) the possibility of applications of CdTe thin films with a Schottky contact as an alternative to the existing X-rays image detectors based on a-Se.
This paper reports on the possible applications of molybdenum oxide (Mo/MoO x) contacts in combin... more This paper reports on the possible applications of molybdenum oxide (Mo/MoO x) contacts in combination with semi-insulating CdTe crystals. The electrical contacts to p-type Cl-doped CdTe crystals were formed by the deposition of molybdenum oxide and pure molybdenum thin films by the DC reactive magnetron sputtering. Electrical properties of the prepared Mo-MoO x /р-CdTe/MoO x-Mo surface-barrier structures were investigated at different temperatures. It is shown that the rapid growth of the reverse current with increasing bias voltage higher than 10 V is caused by the space-charge limited currents. Spectrometric properties of the Mo-MoO x /р-CdTe/MoO x-Mo structures have been also analyzed. It is revealed that the developed heterojunction has shown promising characteristics for its practical application in X-and γ-ray radiation detector fabrication.
ABSTRACT In this paper we report on the strong impact of the concentration of uncompensated impur... more ABSTRACT In this paper we report on the strong impact of the concentration of uncompensated impurities on the detection efficiency of CdTe and Cd 0.9 Zn 0.1 Te Schottky diodes. The results of our study explain the observed poor detection properties of some Cd 0.9 Zn 0.1 Te detectors with resistivity and lifetime of carriers comparable to those of good CdTe detectors. We show that the concentration of uncompensated impurities in a highly efficient CdTe Schottky diode detector is several orders of magnitude higher than that of a CdZnTe, which does not register the gamma spectra of commonly used isotopes (59–662 keV) by using photoelectric measurements. The significant difference of the concentration of uncompensated impurities between CdTe and Cd 0.9 Zn 0.1 Te crystals is confirmed by our study of the temperature change of the resistivity and of the Fermi level energy. The degree of compensation of the donor complex, responsible for the electrical conductivity of the material, is much lower in the CdTe crystal compared to that in the Cd 0.9 Zn 0.1 Te crystal. The calculations of the detection efficiency of x/γ -radiation by a Schottky diode result in a dependence on the concentration of uncompensated impurities described by a curve with a pronounced maximum. The position of this maximum occurs at a concentration of uncompensated impurities which ranges from 3 × 10 10 to 3 × 10 12 cm −3 depending on the registered photon energy of x/γ -rays and on the lifetime of the charge carriers. Our measurements and calculations lead to the conclusion that the concentration of uncompensated impurities in this range is a necessary condition for the effective operation of x-and γ -ray Schottky diode detectors based on CdTe and Cd 1−x Zn x Te crystals.
2016 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room-Temperature Semiconductor Detector Workshop (NSS/MIC/RTSD)
Transport properties of the CdTe X/γ-ray detectors prepared by the deposition of molybdenum oxide... more Transport properties of the CdTe X/γ-ray detectors prepared by the deposition of molybdenum oxide thin films by DC reactive magnetron sputtering onto semi-insulating p-type single-crystal CdTe were studied. Current-voltage characteristics of both detectors with two Ohmic contacts and barrier structure were investigated at different temperatures. The conduction mechanism in the MoOx/p-CdTe/MoOx heterojunction is dominated by generation-recombination in the space-charge region. The Schottky barrier height, concentration of uncompensated impurities and charge carrier lifetime were determined from the comparison of the experimental and calculated results. Finally, the spectra of the Am isotope measured by the detectors are presented. It is shown that the MoMoOx/p+/p-CdTe/p+/MoOx-Mo structures can be used as X/γ-ray detector in the spectrometric mode.
The degree of structural perfection of CdTe:Cl single crystals was estimated by methods of high-r... more The degree of structural perfection of CdTe:Cl single crystals was estimated by methods of high-resolution Xray diffractometry. Two possible systems of dislocations that consists of two sets of complete 60-degree dislocations and Frank partial dislocations were investigated with the use of Krivoglaz kinematic theory and Monte Carlo method. The density of dislocations that provides correspondence between experimental and simulated reciprocal space maps is determined.
The present paper analyzes the сharge transport mechanisms and spectrometric properties of In/CdT... more The present paper analyzes the сharge transport mechanisms and spectrometric properties of In/CdTe/MoOx heterojunctions prepared by magnetron sputtering of indium and molybdenum oxide thin films onto semi-insulating p-type single-crystal CdTe semiconductor, produced by Acrorad Co. Ltd. Current-voltage characteristics of the detectors at different temperatures were investigated. The charge transport mechanisms in the heterostructures under investigation were determined: the generation-recombination in the space charge region (SCR) at relatively low voltages and the space charge limited currents at high voltages. The spectra of 137Cs and 241Am isotopes taken at different applied bias voltages are presented. It is shown that the In/CdTe/MoOx structures can be used as X/γ-ray detectors in the spectrometric mode.
2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2017
Electrical characteristics of the Mo-MoO<inf>x</inf>/p-CdTe/MoO<inf>x</inf&g... more Electrical characteristics of the Mo-MoO<inf>x</inf>/p-CdTe/MoO<inf>x</inf>-Mo, Ti-TiO<inf>x</inf>/p-CdTe/MoO<inf>x</inf>-Mo and Ti-TiN/p-CdTe/MoO<inf>x</inf>-Mo structures, manufactured by magnetron sputtering of the thin films on CdTe semi-insulating crystals, produced by Acrorad Co. Ltd were studied. The optimization of conditions of the substrate pretreatment and the contacts deposition allowed to reduce the dark current of the Mo-MoO<inf>x</inf>/p-CdTe/MoO<inf>x</inf>-Mo detectors compared to earlier analogs and, consequently, to improve its spectrometric characteristics. There was shown that the structure Mo-MoO<inf>x</inf>/p-CdTe/MoO<inf>x</inf>-Mo, TiTiO<inf>x</inf>/p-CdTe/MoO<inf>x</inf>-Mo and Ti-TiN/p-CdTe/MoO<inf>x</inf>-Mo can be used for practical applications in the X- and γ-ray detectors.
2019 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2019
Cadmium telluride (CdTe) is a technologically important II–VI compound semiconductor with a wide ... more Cadmium telluride (CdTe) is a technologically important II–VI compound semiconductor with a wide range of applications which require high-quality and defect-free substrates. Microstructural defects in cadmium telluride crystals can affect performance of CdTe-based semiconductor devices. To study this, the methods of high-resolution X-ray diffraction were used. The Krivoglaz kinematic theory was applied for interpreting experimental data. Evaluation of dislocation density obtained from the analysis values of half-widths rocking curves are presented.
The principle feature limiting spectrometric performance of CdTe and CdMnTe-based X/γ-ray detecto... more The principle feature limiting spectrometric performance of CdTe and CdMnTe-based X/γ-ray detectors is the impossibility to increase the operating voltage to provide sufficient collection of charge carriers because of raising leakage current. We have carried out the detailed analysis of electrical characteristics of CdTe and CdMnTe-based detectors with two Ohmic contacts. It is shown that a rapid increase in leakage current at applying high bias voltage in the CdTe and CdMnTe crystals is caused by the current limited by space charge (SCLC). The same activation energy for the current of equilibrium holes and the current caused by nonequilibrium holes at high voltages confirms the fact that SCLC in the Ni/CdMnTe/Ni detector formed by injection of majority carriers (holes) due to lowering the barrier at an imperfect Ohmic contacts. This fact distinguishes Ni/CdMnTe/Ni detector from Pt/CdTe/Pt detector where SCLC formed by tunnel transitions of minority carriers from the Fermi level in ...
The structure and electrical properties of CdTe Schottky diode X/γ-rays detectors fabricated by D... more The structure and electrical properties of CdTe Schottky diode X/γ-rays detectors fabricated by DC reactive magnetron sputtering of Ti on the surface of semi-insulating p-like CdTe single crystals have been investigated. At relatively low voltages, the current transport processes in the Ti-TiOx/р-CdTe/MoOx-Mo structure are well described in the scope of the carrier generation in the space-charge region and space-charge limited current models. The charge carrier lifetime, energies of generation-recombination centers and hole traps, and density of discrete trapping centers were determined by comparing the experimental and calculation data. Because of the presence of a thin intermediate insulator layer in the р-CdTe/MoOx-Mo contact, a rapid increase in the reverse current due to the Poole-Frenkel emission is observed. The results obtained from the measurements of the I-V characteristics and model of space-charge limited current incorporating the Poole-Frenkel effect are compared and di...
thickness and to use semi-insulating material to provide low leakage current. I-V characteristics... more thickness and to use semi-insulating material to provide low leakage current. I-V characteristics of such type of detectors have unusual view. Most commonly, rectification at low voltages is not observed and forward current steeply increases starting from a few volts rather than at voltage lower than built-in potential. In our contribution we show that electrical characteristics of diodes based on semi-insulating CdTe can be improved using electrode metals with high work functions (Au, Pt, Ni) instead of commonly used In. Both rectifying and near-ohmic contacts were obtained by vacuum deposition of Ni on the opposite crystal surfaces pre-treated by Ar ion bombardment. Ohmic contacts were obtained at the ion beam density 10-15 mA/cm and ion energy 400-500 eV, while Schottky contacts were formed at the ion beam density 2-5 mA/cm and ion energy 700-800 eV. The fabricated Ni/CdTe/Ni detectors exhibit pronounced rectification in the low-voltage region where the I-V characteristics are qu...
2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)
In this paper, the transformations of the morphology and surface structure of CdTe crystals under... more In this paper, the transformations of the morphology and surface structure of CdTe crystals under the action of pulsed laser radiation and the properties of laser-optimized Schottky diode X/γ-ray detectors developed by Ni and NiO deposition onto commercially available (111) oriented CdTe:Cl wafers has been investigated. Using scanning electron and atomic force microscopy, it was shown that, depending on the energy density and laser pulse duration, the morphology, phase composition and distribution of the system of defects and inclusions in the surface areas of CdTe crystals can be optimized. The analysis of the effect of laser treatment on the electrical and spectrometric properties CdTe X/γ-ray detectors under study was also carried out.
Fifteenth International Conference on Correlation Optics
The defects structure, charge collection, and detection efficiency of the Ni(NiO)/p-CdTe/Au/Cu Sc... more The defects structure, charge collection, and detection efficiency of the Ni(NiO)/p-CdTe/Au/Cu Schottky-diode detector have been investigated. The spectroscopic properties of the obtained heterostructures have been studied experimentally and analyzed theoretically. The optimal reverse bias voltage for higher performance of the detectors under study was determined. The reasons of poor charge collection in the detectors and low detection efficiency of photons emitted by an 241Am (59.5 keV) radioisotope have been established and discussed. The techniques of increasing the functional parameters of Ni(NiO)/p-CdTe/Au/Cu Schottky diodes have the investigated and the optimal ways for improvement of the detector performance have been formulated.
Fifteenth International Conference on Correlation Optics
The defect structure of p-CdTe:Cl single crystals and MoOx/p-CdTe/MoOx heterostructures based on ... more The defect structure of p-CdTe:Cl single crystals and MoOx/p-CdTe/MoOx heterostructures based on them were investigated by high-resolution X-ray diffractometry methods. Different models of dislocation systems were applied, according to which the densities of dislocations were estimated from the Wilson-Hall plot. It is shown that the application of the MoOx layer significantly affects the density of dislocations and their influence on the electrical and spectroscopic properties of heterostructures is estimated
Abstract-The charge transport mechanism and spectrometric properties of the Х/-ray detectors, ... more Abstract-The charge transport mechanism and spectrometric properties of the Х/-ray detectors, fabricated by the deposition of molybdenum oxide thin films onto semi-insulating p-CdTe crystals were studied. The current transport processes in the Mo-MoO x /р-CdTe/MoO x-Mo structure are well described in the scope of the carriers generation in the space-charge region and the space charge limited current models. The life time of charge carriers, the energy of holes traps and density of discrete trapping centers were determined from the comparison of the experimental data and calculations. Spectrometric properties of Mo-MoO x /р-CdTe/MoO x-Mo structures were also investigated. It is shown that the investigated heterojunctions have demonstrated promising characteristics for practical application in X/radiation detector fabrication.
This chapter deals with (i) the charge transport mechanisms in X-and gamma-ray detectors both Ohm... more This chapter deals with (i) the charge transport mechanisms in X-and gamma-ray detectors both Ohmic and Schottky types based on CdTe and its alloys with an almost intrinsic conductivity (the peculiarities of the formation of self-compensated complexes due to the doping of Cd(Zn)Te crystals with elements of III or V groups (In, Cl) are taken into account); (ii) the reasons of insufficient energy resolution in the X-and gamma-ray spectra taken with the detectors under study; (iii) the quantitative model which describes the spectral distribution of the detection efficiency of Cd(Zn)Te crystals with Schottky diodes; (iv) a correlation between the concentration of uncompensated impurities in the Cd(Zn)Te crystals and collection efficiency of photogenerated charge carriers in the detectors with a Schottky contact; (v) the possibility of applications of CdTe thin films with a Schottky contact as an alternative to the existing X-rays image detectors based on a-Se.
This paper reports on the possible applications of molybdenum oxide (Mo/MoO x) contacts in combin... more This paper reports on the possible applications of molybdenum oxide (Mo/MoO x) contacts in combination with semi-insulating CdTe crystals. The electrical contacts to p-type Cl-doped CdTe crystals were formed by the deposition of molybdenum oxide and pure molybdenum thin films by the DC reactive magnetron sputtering. Electrical properties of the prepared Mo-MoO x /р-CdTe/MoO x-Mo surface-barrier structures were investigated at different temperatures. It is shown that the rapid growth of the reverse current with increasing bias voltage higher than 10 V is caused by the space-charge limited currents. Spectrometric properties of the Mo-MoO x /р-CdTe/MoO x-Mo structures have been also analyzed. It is revealed that the developed heterojunction has shown promising characteristics for its practical application in X-and γ-ray radiation detector fabrication.
ABSTRACT In this paper we report on the strong impact of the concentration of uncompensated impur... more ABSTRACT In this paper we report on the strong impact of the concentration of uncompensated impurities on the detection efficiency of CdTe and Cd 0.9 Zn 0.1 Te Schottky diodes. The results of our study explain the observed poor detection properties of some Cd 0.9 Zn 0.1 Te detectors with resistivity and lifetime of carriers comparable to those of good CdTe detectors. We show that the concentration of uncompensated impurities in a highly efficient CdTe Schottky diode detector is several orders of magnitude higher than that of a CdZnTe, which does not register the gamma spectra of commonly used isotopes (59–662 keV) by using photoelectric measurements. The significant difference of the concentration of uncompensated impurities between CdTe and Cd 0.9 Zn 0.1 Te crystals is confirmed by our study of the temperature change of the resistivity and of the Fermi level energy. The degree of compensation of the donor complex, responsible for the electrical conductivity of the material, is much lower in the CdTe crystal compared to that in the Cd 0.9 Zn 0.1 Te crystal. The calculations of the detection efficiency of x/γ -radiation by a Schottky diode result in a dependence on the concentration of uncompensated impurities described by a curve with a pronounced maximum. The position of this maximum occurs at a concentration of uncompensated impurities which ranges from 3 × 10 10 to 3 × 10 12 cm −3 depending on the registered photon energy of x/γ -rays and on the lifetime of the charge carriers. Our measurements and calculations lead to the conclusion that the concentration of uncompensated impurities in this range is a necessary condition for the effective operation of x-and γ -ray Schottky diode detectors based on CdTe and Cd 1−x Zn x Te crystals.
2016 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room-Temperature Semiconductor Detector Workshop (NSS/MIC/RTSD)
Transport properties of the CdTe X/γ-ray detectors prepared by the deposition of molybdenum oxide... more Transport properties of the CdTe X/γ-ray detectors prepared by the deposition of molybdenum oxide thin films by DC reactive magnetron sputtering onto semi-insulating p-type single-crystal CdTe were studied. Current-voltage characteristics of both detectors with two Ohmic contacts and barrier structure were investigated at different temperatures. The conduction mechanism in the MoOx/p-CdTe/MoOx heterojunction is dominated by generation-recombination in the space-charge region. The Schottky barrier height, concentration of uncompensated impurities and charge carrier lifetime were determined from the comparison of the experimental and calculated results. Finally, the spectra of the Am isotope measured by the detectors are presented. It is shown that the MoMoOx/p+/p-CdTe/p+/MoOx-Mo structures can be used as X/γ-ray detector in the spectrometric mode.
The degree of structural perfection of CdTe:Cl single crystals was estimated by methods of high-r... more The degree of structural perfection of CdTe:Cl single crystals was estimated by methods of high-resolution Xray diffractometry. Two possible systems of dislocations that consists of two sets of complete 60-degree dislocations and Frank partial dislocations were investigated with the use of Krivoglaz kinematic theory and Monte Carlo method. The density of dislocations that provides correspondence between experimental and simulated reciprocal space maps is determined.
The present paper analyzes the сharge transport mechanisms and spectrometric properties of In/CdT... more The present paper analyzes the сharge transport mechanisms and spectrometric properties of In/CdTe/MoOx heterojunctions prepared by magnetron sputtering of indium and molybdenum oxide thin films onto semi-insulating p-type single-crystal CdTe semiconductor, produced by Acrorad Co. Ltd. Current-voltage characteristics of the detectors at different temperatures were investigated. The charge transport mechanisms in the heterostructures under investigation were determined: the generation-recombination in the space charge region (SCR) at relatively low voltages and the space charge limited currents at high voltages. The spectra of 137Cs and 241Am isotopes taken at different applied bias voltages are presented. It is shown that the In/CdTe/MoOx structures can be used as X/γ-ray detectors in the spectrometric mode.
2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2017
Electrical characteristics of the Mo-MoO<inf>x</inf>/p-CdTe/MoO<inf>x</inf&g... more Electrical characteristics of the Mo-MoO<inf>x</inf>/p-CdTe/MoO<inf>x</inf>-Mo, Ti-TiO<inf>x</inf>/p-CdTe/MoO<inf>x</inf>-Mo and Ti-TiN/p-CdTe/MoO<inf>x</inf>-Mo structures, manufactured by magnetron sputtering of the thin films on CdTe semi-insulating crystals, produced by Acrorad Co. Ltd were studied. The optimization of conditions of the substrate pretreatment and the contacts deposition allowed to reduce the dark current of the Mo-MoO<inf>x</inf>/p-CdTe/MoO<inf>x</inf>-Mo detectors compared to earlier analogs and, consequently, to improve its spectrometric characteristics. There was shown that the structure Mo-MoO<inf>x</inf>/p-CdTe/MoO<inf>x</inf>-Mo, TiTiO<inf>x</inf>/p-CdTe/MoO<inf>x</inf>-Mo and Ti-TiN/p-CdTe/MoO<inf>x</inf>-Mo can be used for practical applications in the X- and γ-ray detectors.
2019 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2019
Cadmium telluride (CdTe) is a technologically important II–VI compound semiconductor with a wide ... more Cadmium telluride (CdTe) is a technologically important II–VI compound semiconductor with a wide range of applications which require high-quality and defect-free substrates. Microstructural defects in cadmium telluride crystals can affect performance of CdTe-based semiconductor devices. To study this, the methods of high-resolution X-ray diffraction were used. The Krivoglaz kinematic theory was applied for interpreting experimental data. Evaluation of dislocation density obtained from the analysis values of half-widths rocking curves are presented.
The principle feature limiting spectrometric performance of CdTe and CdMnTe-based X/γ-ray detecto... more The principle feature limiting spectrometric performance of CdTe and CdMnTe-based X/γ-ray detectors is the impossibility to increase the operating voltage to provide sufficient collection of charge carriers because of raising leakage current. We have carried out the detailed analysis of electrical characteristics of CdTe and CdMnTe-based detectors with two Ohmic contacts. It is shown that a rapid increase in leakage current at applying high bias voltage in the CdTe and CdMnTe crystals is caused by the current limited by space charge (SCLC). The same activation energy for the current of equilibrium holes and the current caused by nonequilibrium holes at high voltages confirms the fact that SCLC in the Ni/CdMnTe/Ni detector formed by injection of majority carriers (holes) due to lowering the barrier at an imperfect Ohmic contacts. This fact distinguishes Ni/CdMnTe/Ni detector from Pt/CdTe/Pt detector where SCLC formed by tunnel transitions of minority carriers from the Fermi level in ...
The structure and electrical properties of CdTe Schottky diode X/γ-rays detectors fabricated by D... more The structure and electrical properties of CdTe Schottky diode X/γ-rays detectors fabricated by DC reactive magnetron sputtering of Ti on the surface of semi-insulating p-like CdTe single crystals have been investigated. At relatively low voltages, the current transport processes in the Ti-TiOx/р-CdTe/MoOx-Mo structure are well described in the scope of the carrier generation in the space-charge region and space-charge limited current models. The charge carrier lifetime, energies of generation-recombination centers and hole traps, and density of discrete trapping centers were determined by comparing the experimental and calculation data. Because of the presence of a thin intermediate insulator layer in the р-CdTe/MoOx-Mo contact, a rapid increase in the reverse current due to the Poole-Frenkel emission is observed. The results obtained from the measurements of the I-V characteristics and model of space-charge limited current incorporating the Poole-Frenkel effect are compared and di...
thickness and to use semi-insulating material to provide low leakage current. I-V characteristics... more thickness and to use semi-insulating material to provide low leakage current. I-V characteristics of such type of detectors have unusual view. Most commonly, rectification at low voltages is not observed and forward current steeply increases starting from a few volts rather than at voltage lower than built-in potential. In our contribution we show that electrical characteristics of diodes based on semi-insulating CdTe can be improved using electrode metals with high work functions (Au, Pt, Ni) instead of commonly used In. Both rectifying and near-ohmic contacts were obtained by vacuum deposition of Ni on the opposite crystal surfaces pre-treated by Ar ion bombardment. Ohmic contacts were obtained at the ion beam density 10-15 mA/cm and ion energy 400-500 eV, while Schottky contacts were formed at the ion beam density 2-5 mA/cm and ion energy 700-800 eV. The fabricated Ni/CdTe/Ni detectors exhibit pronounced rectification in the low-voltage region where the I-V characteristics are qu...
2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)
In this paper, the transformations of the morphology and surface structure of CdTe crystals under... more In this paper, the transformations of the morphology and surface structure of CdTe crystals under the action of pulsed laser radiation and the properties of laser-optimized Schottky diode X/γ-ray detectors developed by Ni and NiO deposition onto commercially available (111) oriented CdTe:Cl wafers has been investigated. Using scanning electron and atomic force microscopy, it was shown that, depending on the energy density and laser pulse duration, the morphology, phase composition and distribution of the system of defects and inclusions in the surface areas of CdTe crystals can be optimized. The analysis of the effect of laser treatment on the electrical and spectrometric properties CdTe X/γ-ray detectors under study was also carried out.
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Papers by O. Maslyanchuk