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
This paper reports the results of an investigation of the electrical and photoelectrical properties of the Graphite/PEDOT:PSS/n-CdZnTe organic-inorganic heterojunction formed by the deposition of thin films PEDOT:PSS on CdZnTe substrates. The Cd1–xZnxTe solid solution with low Zn content was grown by the Bridgman method at low cadmium vapor pressure and had a low resistivity ρ ≈ 102 Ohm•cm. The values of the series resistance Rs and shunt resistance Rsh of the Graphite/PEDOT:PSS/n-CdZnTe organic-inorganic heterojunction were determined from the dependence of their differential resistance Rdif. The temperature dependencies of the height of the potential barrier of the Graphite/PEDOT:PSS/n-CdZnTe organic-inorganic heterojunction was determined from the I-V characteristics. The dominating current transport mechanisms through the Graphite/PEDOT:PSS/n-CdZnTe organic-inorganic heterojunctions were determined.
Schottky graphite / p-InP diodes were first fabricated by transferring the drawn graphite film to an InP substrate with a hole-type conductivity. As a result of research, the main mechanisms of current transfer through Schottky diodes graphite / p-InP were determined: these are multistage tunneling-recombination processes involving surface states at the graphite / p-InP interface and tunneling, which is described by Newman's formula at direct displacement; tunneling with reverse displacement. The studied heterojunctions have pronounced diode characteristics with a rectification coefficient k ≈ 102 (at V = 1 V). It is shown that the created graphite / p-InP Schottky diodes have a potential barrier height of 0.71 eV
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.
TiN thin films were deposited are deposited by DC reactive magnetron sputtering. The effect of annealing on the electrical and optical properties of the thin films was investigated. Temperature dependences of the resistance R of the TiN films were measured within the temperature range T ÷ 295-420 K. There was established that all samples under investigation had n-type of conductivity. Based on the dependences (αhν)2 = f(hν), the presence of direct allowed interband optical transitions in the TiN thin films is established and the optical band gap values before and after annealing are determined. Annealing in nitrogen atmospheres led to an increase in the optical width of the band gap, which may be due to deviations from the stoichiometric composition of thin TiN films during heat treatment.
The results of investigation of optical and electrical properties of p-Cu2FeSnS4 thin polycrystalline films obtained by spray pyrolysis of aqueous solutions of salts of CuCl2∙2H2O, FeCl3∙6H2O and SnCl4∙5H2O and (NH2)2CS are presented. On the basis of the analysis of the light absorption spectra, the optical band gap of the films Eg ≈ 1.72 eV was determined and the dynamics of its change during thermal treatment under low vacuum conditions (0.1 Pa). The conductivity activation energies (Ea = 0.75 eV) and the height of the energy barriers between the grain boundaries (Eb = 0.07 eV) are determined from the temperature dependences of the electrical conductivity.
Chromium nitride (CrxN) thin films were deposited by DC reactive magnetron sputtering at different ratios between partial pressures of nitrogen. Electrical and optical properties of the thin films were investigated. Temperature dependences of the resistance R of the CrxN films were measured within the temperature range T ÷ 295-420 K. Based on the dependences α2 = f(hν), the presence of direct allowed interband optical transitions in the CrxN thin films is established and the optical band gap values are determined for all sample before and after annealing.
W2N thin films were prepared by DC reactive magnetron sputtering. The optical and electrical properties of the obtained thin films were investigated. The transmission spectra of thin films of tungsten nitride (deposited on glass substrates) were analyzed. The optical band gap is determined. The electrical resistance of the films is analyzed.
p-NiO/n-CdTe-photosensitive heterojunctions were prepared by the deposition of nickel oxide thin films onto n-type single-crystal CdTe substrates by DC reactive magnetron sputtering. The analysis of capacitance-voltage (C−V) characteristics, measured at different frequencies of the small amplitude AC signal and corrected by the effect of the series resistance, provided evidence of the presence of electrically charged interface states, which significantly affect the measured capacitance. The dominant current transport mechanisms in the heterojunctions were determined at forward and reverse biases. Using “light” I−V characteristics, we determined the open-circuit voltage Voc=0.42 V, the short-circuit current Isc=57.5 μA/cm2, and the fill factor FF=0.24 under white light illumination with the intensity of 80 mW/cm2.
MoOx thin films were deposited are deposited by DC reactive magnetron sputtering at different technological conditions. Structural, electrical and optical properties of the thin films were investigated. Temperature dependences of the resistance R of the MoOx films were measured within the temperature range T ÷ 295-420 K. There was established that all samples under investigation had n-type of conductivity. Based on the dependences α2 = f(hν ), the presence of direct allowed interband optical transitions in the MoOx thin films is established and the optical band gap values are determined.
This paper reports optical properties of n-type SnS2 thin films, prepared by spin-coating of a sol-gel based on the lowcost and environmentally friendly solvent dimethyl sulfoxide (DMSO). The effect of a short-term low-temperature treatment in air and final annealing under low vacuum (0.1 Pa) on the synthesis of tin disulfide films was tested and analyzed. The dynamics of changes of optical properties of the films on the parameters of spin-coating and heat treatment was established. The value of the band gap Eg ≈ 2.25 – 2.54 eV for SnS2 and Eg ≈ 1.99 eV for Sn2S3 was determined from the analysis of optical characteristics.
The results of an experimental study of the polarization characteristics of thin films based on aluminum nitride (AlN) are presented. It was found that an increase in the partial pressure of nitrogen (with the appropriate technology for producing the AlN film) leads to a substantial increase in the absorptivity of the film itself and a decrease in its linear dichroism parameter.
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.
MoOx/n-CdTe photosensitive heterostructures were prepared by the deposition of molybdenum oxide thin films onto three different n-type CdTe substrates (ρ1=0.4 Ω⋅cm, ρ2=10 Ω⋅cm, ρ3=40 Ω⋅cm) by DC reactive magnetron sputtering. The height of the potential barrier and series resistance of the MoOx/CdTe heterojunctions were investigated. The dominating current transport mechanisms through the heterojunctions were determined at forward and reverse biases.
Graphite/n-SiC Shottky diodes were prepared by means of the recently proposed technique based on the transferring of drawn graphite films onto the n-SiC single crystal substrate. Current-voltage characteristics were measured and analyzed. High quality ohmic contancts were prepared by the DC magnetron sputtering of Ni thin films onto cleaved n-type SiC single crystal substrates. The height of the potential barrier and the series resistance of the graphite/n-SiC junctions were measured and analysed. The dominant current transport mechanisms through the diodes were determined. There was shown that the dominant current transport mechanisms through the graphite/n-SiC Shottky diodes were the multi-step tunnel-recombination at forward bias and the tunnelling mechanisms at reverse bias.
We report the results of the investigation of morphological, structural, optical and plarimeteric properties of titanium nitride thin films deposited on silicon and glass substrates.
The magnetron sputtered titanium nitride thin films were established to possess crystalline structure with the average grain size about D = 15 nm.
The method of correlation matrix is was applied for the analysis of polarization properties of scattered light by the titanium nitride thin film. The obtained experimental result, can be explained by the presence of the effects of linear and circular dichroism in the material of the titanium nitride thin films under investigations.
We report the results of the investigation of electrical properties of photosensitive anisotype heterojunctions n- TiN/p-Si with different conditions of Si surface treatments. The analysis of the measured I-V characteristics of the heterojunctions under dark conditions has shown that values of the height of the potential barrier and series resistance decreases with the decrease of the thickness of native oxide. The dominating tunnel-recombination mechanism of current transport through the heterojunctions under investigation was determined to be independent on the conditions of surface treatment. We have established that the n-TiN/p-Si heterojunction oxidized in bidistilled water at 70ºC for 30 s possesses the lowest density of interface states and, thus lowest surface recombination velocity.
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