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Radiation-induced effects in Cu(In,Ga)Se2 alloy thin films after implantation with hydrogen ions with energies of 2.5, 5, and 10 keV and a dose of ~3 × 1015 cm–2 are studied. Comparative analysis of the optical characteristics of nonimplanted and hydrogen-implanted Cu(In,Ga)Se2 films is conducted on the basis of photoluminescence spectra and luminescence-excitation spectra recorded at liquid-helium temperature (~4.2 K). The band gap determined for Cu(In,Ga)Se2 alloys by mathematical processing of the luminescence-excitation spectra is ~1.171 eV. In the photoluminescence spectra of nonimplanted and hydrogen-implanted Cu(In,Ga)Se2 films, an intense band is detected, with a maximum at ~1.089 eV. The band is defined by the recombination of free electrons with holes localized in the valence-band tails. It is established that broad bands with maximums at the energies 0.92 and ~0.77 eV are defined by the radiative recombination of nonequilibrium charge carriers at deep energy levels of ion-induced acceptor defects formed in the band gap of Cu(In,Ga)Se2 alloys. The conditions for the effect of the ion passivation of dangling electron bonds at the surface and in the bulk of polycrystalline Cu(In,Ga)Se2 films and the nature of structural point defects and the mechanisms of radiative recombination are discussed.

The results of studying the optical transmission, photoconductivity, photoluminescence, and X-ray diffraction of HgCdTe solid-solution samples with a high content of CdTe (molar fraction 0.7–0.8), grown by molecular-beam epitaxy (MBE) and liquid-phase epitaxy (LPE), are presented. It is shown that the material under study shows a significant degree of disorder of the solid solution, which is greater in structures grown by MBE on GaAs substrates, compared with the LPE-grown films. A study of the photoluminescence reveals states in the band gap, previously considered untypical of HgCdTe films grown on GaAs substrates, but typical only of films grown on Si. On the whole, the high quality of the material with a high CdTe content, grown by MBE and used to create the HgTe/HgCdTe nanostructures currently in high demand, is confirmed.

The emission spectra of thin nanocrystalline films of Cu(In1 – xGax)(SySe1 – y)2 (CIGSSe) direct-gap solid solutions in the structure of solar cells, recorded upon continuous-wave laser excitation (~0.5 W/cm2) and nanosecond pulsed laser excitation with a power density in the range of 0.1–53 kW/cm2 at temperatures ranging from 10 to 300 K, are analyzed. It is found that stimulated emission (SE) occurs in thin CIGSSe films at temperatures from 10 to 90 K in the spectral range hν = 1.062–1.081 eV, with a minimum threshold-pump level of ~1 kW/cm2. It is shown that the spontaneous emission band is blue-shifted with an increase in the excitation intensity. It is also established that, with an increase in temperature, the photoluminescence (PL) band (upon weak excitation) and the stimulated-emission band are blue-shifted, whereas the PL band is red-shifted upon strong excitation. The possible reasons and mechanisms for the influence of temperature and excitation intensity on the spectral positions of the spontaneous and stimulated emission bands for the solid-solution films are discussed.

An ellipsometric procedure developed for noncontact in situ measurement of the CdTe buffer-layer temperature is presented. The procedure is based on the temperature dependence of the energy position of CdTe critical points and is intended for determining the initial temperature of the growth surface before epitaxy of the cadmium–mercury–telluride compound. An express method for determining the position of critical points by the spectra of ellipsometric parameter Ψ is proposed. A series of calibrated experiments is performed. They result in determination of the temperature dependences of the position of critical points. Estimations and the experiment show that the temperature-measurement accuracy is ±3°C.

The stimulated emission of Cu(In,Ga)Se2 alloy thin films formed by magnetron-assisted sputtering onto a sodium-fluoride layer deposited onto a molybdenum layer on a glass substrate is observed. The structural and optical parameters of the films are determined by scanning electron microscopy, local X-ray spectral microanalysis, X-ray structural analysis, and low-temperature luminescence (T = 10 K) measurements in the range of excitation levels of 1.6–75 kW cm–2 provided by nanosecond nitrogen-laser pulses. The stimulated emission threshold corresponds to ~25 kW cm–2. Comparative analysis of the emission of Cu(In,Ga)Se2 thin films suggests that the introduction of sodium results in significant improvement of the structural quality, specifically, in a decrease in the density of energy states in the band tails and in a decrease in the concentration of nonradiative-recombination centers.

The parameters of multilayer CdxHg1–xTe heterostructures for photodetectors operating at wavelengths of up to 5 μm, grown by molecular-beam epitaxy (MBE) on silicon substrates, are studied. The passivating properties of thin CdTe layers on the surface of these structures are analyzed by measuring the C–V characteristics. The temperature dependences of the minority carrier lifetime in the photoabsorption layer after growth and thermal annealing are investigated. Samples of p+–n-type photodiodes are fabricated by the implantation of arsenic ions into n-type layers, doped with In to a concentration of (1–5) × 1015 cm–3. The temperature dependences of the reverse currents are measured at several bias voltages; these currents turn out to be almost two orders of magnitude lower than those for n+–p-type diodes.

Defects in mercury-cadmium-telluride heteroepitaxial structures (with 0.3 to 0.4 molar fraction of cadmium telluride) grown by molecular-beam epitaxy on silicon substrates are studied. The low-temperature photoluminescence method reveals that there are comparatively deep levels with energies of 50 to 60 meV and shallower levels with energies of 20 to 30 meV in the band gap. Analysis of the temperature dependence of the minority carrier lifetime demonstrates that this lifetime is controlled by energy levels with an energy of ∼30 meV. The possible relationship between energy states and crystal-structure defects is discussed.

Heteroepitaxial structures n-CdxHg1 − xTe for the near-infrared spectral range (x ≈ 0.4) are grown by molecular beam epitaxy on Si(310) substrates 72.6 and 100 mm in diameter. High composition homogeneity over the structure area is attained; the variation in x for 100-mm wafers is 0.015–0.025. During growth, the mercury-cadmium telluride (MCT) layers are doped with In with the concentration (0.5–3) × 1015 cm−3. The magnetic-field dependences of the Hall effect are studied in the range of magnetic fields 0.05–1.0 T at liquid-nitrogen and room temperatures. The experimental values of the electron mobility at room temperature are close to the calculated ones, while at liquid-nitrogen temperature, they are lower than the calculated mobilities. The possible causes of this phenomenon such as the influence of the MCT transition layer at the interface with the CdTe buffer layer and lattice defects of MCT are discussed. The variation in the concentration and mobility of charge carriers in MCT structures after activation annealing are studied.

The photoluminescence (PL) of CdHgTe solid solutions subjected to low-energy ion treatment is studied. A blue shift of the peaks in the PL spectra is observed immediately after ion treatment, which is attributed to the formation of a high concentration of donor defects and to the Burstein-Moss effect. The change in the shape of the PL spectra and, in particular, the disappearance of lines associated with transitions to acceptor states indicate that these defects are formed by the interaction of interstitial mercury atoms introduced into the sample during the course of treatment with impurity atoms. As the treatment is terminated, the electron concentration decreases due to the disintegration of defects and the blue shift disappears, but the shape of the spectra remains unchanged. This behavior of the PL spectra can be used for diagnostics of the defect-impurity structure of CdHgTe.

The electrical and optical properties of epitaxial CdHgTe films grown on silicon substrates by molecular-beam epitaxy have been studied. The results of photoluminescence measurements are indicative of the high structural perfection of the films, and Hall data combined with low-energy ion treatment point to a low concentration of residual donors (∼5 × 1014 cm−3). Acceptor states supposedly related to the capture of impurities at structural defects typical of strongly lattice-mismatched heteroepitaxial structures are found in the films.

Microstructure of the CdTe (310) and CdHgTe (310) layers grown by molecular-beam epitaxy on Si substrates has been studied by the methods of transmission electron microscopy and selective etching. It is established that formation of antiphase domains in the CdHgTe/CdTe/ZnTe/Si(310) is determined by the conditions of formation of the ZnTe/Si interface. Monodomain layers can be obtained by providing conditions that enhance zinc adsorption. An increase in the growth temperature and in the pressure of Te2 vapors gives rise to antiphase domains and induces an increase in their density to the extent of the growth of poly-crystals. It is found that stacking faults exist in a CdHgTe/Si(310) heterostructure; these defects are anisotropically distributed in the bulk of grown layers. The stacking faults are predominantly located in one (111) plane, which intersects the (310) surface at an angle of 68°. The stacking faults originate at the ZnTe/Si(310) interface. The causes of origination of stacking faults and of their anisotropic distribution are discussed.

Photoluminescence (PL) of Hg1 − x Cd x Te-based heterostructures grown by molecular-beam epitaxy (MBE) on GaAs and Si substrates has been studied. It is shown that a pronounced disruption of the long-range order in the crystal lattice is characteristic of structures of this kind. It is demonstrated that the observed disordering is mostly due to the nonequilibrium nature of MBE and can be partly eliminated by postgrowth thermal annealing. Low-temperature spectra of epitaxial layers and structures with wide potential wells are dominated by the recombination peak of an exciton localized in density-of-states tails; the energy of this peak is substantially lower than the energy gap. In quantum-well (QW) structures at low temperatures, the main PL peak is due to carrier recombination between QW levels and the energy of the emitted photon is strictly determined by the effective (with the QW levels taken into account) energy gap.

Results of studies of the molecular beam epitaxial growth of HgCdTe alloys on Si substrates as large as 100 mm in diameter are presented. Optimum conditions for obtaining HgCdTe/Si(310) heterostructures of the device quality for the spectral range of 3–5 μm are determined. The results of measurements and discussion of photoelectric parameters of an infrared photodetector of a format of 320 × 256 elements with a step of 30 μm based on a hybrid assembly of a matrix photosensitive cell with a Si multiplexer are presented. A high stability of photodetector parameters to thermocycling from room temperature to liquid-nitrogen temperature is shown.

A hardware-software complex based on a spectroscopic ellipsometer integrated into a molecular beam epitaxy installation and destined to monitor the composition of the Cd1 − zZnzTe alloy at small values of z is described. Methodical features of determination of the composition of growing layers by the spectra of ellipsometric parameters are considered. The procedure of determination of the composition by the absorption edge that allows measuring this parameter accurate to 1.2% is developed. Problems are considered the solutions of which will allow one to increase the resolution by the composition. In particular, maintaining a stable temperature during growth is required for this purpose.

Heterojunctions based on p-CuIn3Se5 crystals are fabricated by magnetron sputtering of an n-ZnO:Al target and by putting naturally cleaved n-GaSe thin wafers onto polished surfaces of p-CuIn3Se5 wafers. The current-voltage characteristics and mechanisms of current flow in the diodes under study are analyzed. The photovoltaic effect revealed in the fabricated structures is discussed. It is shown that the fabricated photosensitive heterojunctions are promising for the development of selective analyzers of linearly polarized radiation.

Anomalous electrical properties have been observed in CdxHg1−xTe films grown on GaAs substrates by MBE at elevated temperature. The anomalies are manifested in the conductivity anisotropy, modifications of the transmission and photoconductivity spectra upon low-temperature annealing, and the existence of a periodic undulatory surface microprofile. The temperature dependence of conductivity along and across the microprofile waves has been studied. It is suggested that a CdxHg1−xTe film with anomalous electrical properties is a spontaneously formed periodic structure in the form of vertical nanowalls of different compositions. Possible mechanisms for the formation of such a structure are discussed.

Homogeneous crystals of CuIn3Se5, CuGa3Se5, and CuGa5Se8 ternary compounds were grown, and their physical and chemical properties were investigated. Photosensitive structures were fabricated for the first time on the basis of these compounds, and the spectral dependence of the relative quantum photoconversion efficiency was measured. The bandgap of these compounds was also estimated, and it was shown that direct interband transitions are typical in them. It was found that the content and chemical nature of atoms forming an elementary cell in a I-IIIn-VIm ternary compound control the relevant band gap.

Growth processes were considered for heteroepitaxial structures based on a mercury-cadmium-telluride (MCT) solid solution deposited on GaAs and Si alternative substrates by molecular-beam epitaxy. Physical and chemical processes of growth and defect-generation mechanisms were studied for CdZnTe epitaxy on atomically clean singular and vicinal surfaces of gallium-arsenide substrates and CdHgTe films on CdZnTe/GaAs surfaces. ZnTe single-crystalline films were grown on silicon substrates. Methods for reducing the content of defects in CdZnTe/GaAs and CdHgTe films were developed. Equipment for molecular-beam epitaxy was designed for growing the heteroepitaxial structures on large-diameter substrates with a highly uniform composition over the area and their control in situ. Heteroepitaxial MCT layers with excellent electrical parameters were grown on GaAs by molecular-beam epitaxy.