I. N. Odin

Luminescent properties of CdS crystals doped with gallium and tellurium in cadmium vapor

A technique is devised for vapor-phase doping CdS in the quaternary system Cd–Ga–Te–S. CdS crystals are doped with Ga and Te via four-zone annealing in a vapor phase containing Ga, Te, and Cd (the more volatile component of CdS). The luminescence spectra of the CdS〈Ga,Te〉[Cd] crystals are found to contain orange and red emission bands, in contrast to those of CdS[Cd] crystals, which are dominated by green emission.

Cathodoluminescence of photosensitive CdSe layers grown in a quasi-closed system

We report conditions for the growth of photosensitive CdSe epilayers on mica (muscovite) substrates in a quasi-closed system. At a substrate temperature of 600°C and source evaporation temperature of 680°C, the most perfect photosensitive wurtzite CdSe epilayers can be grown. Such layers show bright free-exciton luminescence at 78 K.

Effect of self-compensation on the electron lifetime in gallium-doped cadmium telluride

Using the methods of microwave photoconductivity and cathodoluminescence, elementary processes with the participation of charged particles in polycrystalline alloys on the basis of cadmium telluride CdTe-GaTe and CdTe-Ga2Te3—promising active media for radiation detectors in low-dose human introscopy—are studied. It is established experimentally that the amplitude, characteristic time, and shape of decay of the photoresponse depend on the doping level, and the characteristic time of the photoresponse increases as the doping level is increased. It is shown that the change in the kinetics of annihilation of photo-generated electrons in doped cadmium telluride (compared with the starting one) is caused by the effect of self-compensation, which leads to redistribution of traps by energies.

Kinetics of electron-ion processes in CdTe-based solid solutions in the CdTe-CdI2 system

Single-crystal and polycrystalline CdTe-CdI2 solid solutions containing 0.016 to 0.350 mol % CdI2 have been studied using microwave photoconductivity measurements. The results demonstrate that the magnitude of their photoresponse and the shape of the photoresponse decay curve depend on the doping level and the degree of dispersion. The observed effect of doping level on the photogenerated electron decay kinetics in cadmium telluride is interpreted in terms of self-compensation, which leads to redistribution of trap energies. The recombination rate constant for free electrons and holes in CdTe is determined to be (3 ± 1) × 10−11 cm3/s, independent of the doping level and the degree of dispersion of the samples.

Influence of conditions of electrochemical deposition on properties of nanocrystalline CuInSe2 films

The influence of the potentials and time of electrochemical deposition from ethanol solutions on the phase composition, structure, optical properties, and adhesion of the nanocrystalline CuInSe2 (CIS) films has been investigated. The range of the potentials in which single-phase CIS thin films form with the best adhesion is defined based on X-ray diffraction (XRD) and atomic force microscopy (AFM). The size of the coherent scattering region is estimated according to XRD as 6 nm. Using AFM measurements, it is revealed that the films consist of conglomerates (∼200 nm) of nanoparticles, and the size (<10 nm) is dependent on time and deposition potential. The band gap width of the synthesized single-phase films, estimated on the optical absorption spectra, is about 1.5 eV.

Luminescence properties of CdTe-based solid solutions in the CdTe-Ga2Te3 and CdTe-GaTe systems

The extent of the cadmium-telluride-based solid solution along the CdTe-GaTe join at 737°C has been determined from the composition dependence of its unit-cell parameter. The cathodoluminescence spectra of CdTe-based solid solutions in the CdTe-GaTe and CdTe-Ga2Te3 systems have been measured. The 895-nm band observed in the 78-K spectrum of the Ga2Te3-containing solid solution is due to the [GaCd·VCd] radiative defect complex. The spectra of the CdTe-GaTe solid solutions seem to show a superposition of two lines close in position, attributable to the [GaCd·VCd] and [GaCd′VTe] defect complexes.

Luminescent properties of Cd-In-Te solid solutions

The composition dependences of the unit-cell parameter for CdTe-based solid solutions in the CdTe-InTe and CdTe-In4Te3 joins have been used to determine the limits of the solid solutions. Magnetic susceptibility data and the measured and X-ray densities of the solid solutions suggest that CdTe doped with In2Te2 or In4Te3 contains In+ and In3+ on the cation site. The cathodoluminescence spectra of CdTe doped with In2Te2, In4Te3, and In2Te3 have been measured, and the effect of mixed heterovalent substitution (In+ and In3+) on the luminescence behavior of CdTe has been analyzed.

Phase Diagram and Luminescent Properties of CdTe–MnTe Solid Solutions

The T–x phase diagram of the CdTe–MnTe system is mapped out. The CdTe–MnTe join is shown to be nonpseudobinary. The system contains an extended series of CdTe-based solid solutions (0–71.4 mol % MnTe at 1070 K). At 1070 K, α-MnTe dissolves up to 0.3 mol % CdTe. Data are presented on the composition dependences of lattice parameters for the solid solutions studied and the luminescent properties of Cd1 – xMnxTe single crystals annealed in cadmium or tellurium vapor.

Cathodoluminescence of Cd4SiS6 , Cd4SiSe6 , and Si-Doped CdS, CdSe, and CdTe Crystals

CdS, CdSe, and CdTe single crystals were vapor-phase-doped with the corresponding silicon chalcogenides under nearly equilibrium conditions. Cathodoluminescence studies revealed that the Si dopant produced new luminescence centers in the crystals. The cathodoluminescence spectra of Cd4SiS6and Cd4SiSe6crystals were measured. Metastable, sphalerite CdS〈Si〉 and CdSe〈Si〉 films were grown under highly nonequilibrium conditions. The maximum of edge emission in their spectra was redshifted as compared to the stable materials. The CdS〈Si〉 and CdSe〈Si〉 crystals were shown to be photosensitive.

Synthesis, structure, and luminescence properties of Cd1–x Mg x Te (0 < x < 0.20) solid solutions

We have synthesized CdTe–MgTe samples in the composition range 0–30 mol % MgTe. The composition dependence of the unit-cell parameter of the Cd1–xMxTe solid solutions has been obtained for the first time. The lattice parameter of cadmium telluride (sphalerite structure) has been shown to decrease almost linearly in the range 0 ≤ x ≤ 0.20. The 78-K cathodoluminescence spectra of the Cd1–xMgxTe (0 < x ≤ 0.15) solid solutions heat-treated under vacuum in order to remove the excess tellurium contain strong lines in the edge emission region, due to a transition from the conduction band to a shallow acceptor level.