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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.

Plasmonic enhancement of the photoluminescence in hybrid structures with SiGe quantum dots and Ag nanoislands was found. Ag nanoislands grown on the top of the multilayer structures with SiGe quantum dots (QDs) support a surface plasmon resonance that can be tuned to the QD emission wavelength by changing of Ag nanoparticle parameters. Photoluminescence measurements of the hybrid metal-semiconductor nanostructures revealed a fourfold increase of the integral intensity of SiGe QD emission in the spectral range from 0.8 to 1 eV.

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.

An approach for the formation of ordered groups of Ge nanoislands (quantum dots, QDs) upon epitaxial growth on the surface of a heterostructure constituted by a Si (100) substrate having preliminarily formed seeds in the form of disk-like SiGe nanomounds is developed. It is found that the observed arrangement of QDs within a group is due to the anisotropic elastic-strain energy distribution on the surface of a SiGe nanomound, namely, to the existence of four local energy minima arranged in an ordered manner along the [100] and [010] directions with respect to the seed center. Multilayer structures with vertically aligned QD groups are grown using the suggested approach. The crystal structure and the elemental composition of the spatially ordered nanostructures are examined by transmission electron microscopy, X-ray diffraction analysis, and Raman spectroscopy.

The results of X-ray diffraction and optical studies of Cu2ZnSnS4 films produced by the flash evaporation of binary sulfide compounds under different technological conditions is reported. It is shown that it is possible to produce Cu2ZnSnS4 films, rather perfect in structural and optical respects, by choosing the optimal annealing temperatures at different Ar vapor pressures. The lattice parameters of the compounds are determined. The systematic shift in the photoluminescence bands under variations in the excitation level is established. It is found that the characteristics of the bands depend to a large extent on the annealing temperature, the Ar pressure during thermal treatment, and the resultant stoichiometry composition of the samples. It is shown that Raman studies and luminescence measurements can be used to assess the quality of the synthesized Cu2ZnSnS4 films and to obtain data on the energy structure of defects in the band gap.

Based on a colloidal solution containing terbium, yttrium, and aluminum metal ions, a powder was synthesized and films of terbium-doped yttrium aluminum garnet Tb0.15Y2.85Al5O12 were grown on single-crystal silicon and porous anodic alumina. Annealing of the sample in a temperature range from 200–1100°C results in an increase in the photoluminescence intensity in the wavelength range from 480–640 nm, which is caused by Tb3+ ion intra-atomic transitions 5D4→7Fj (j = 3, 4, 5, 6). Annealing at 900°C and higher temperatures gives rise to low-intensity photoluminescence bands in the region of 667 and 681 nm, which correspond to transitions 5D4→7F0, 5D4→7F1, and room-temperature Stark term splitting, which suggests the existence of a crystalline environment of Tb3+ ions. The FWHM of spectral lines in the region of 543 nm decreases from ∼10 to ∼(2–3) nm as the xerogel annealing temperature is increased from 700 to 900°C and higher. Three bands with maxima at 280, 330, and 376 nm, which correspond to Tb3+ ion transitions 7F6→5I8, 5L6, 5G6, 5D3, are observed in the photoluminescence excitation spectra of the studied structures for the emission wavelength at 543 nm. X-ray diffraction detected the formation of a crystalline phase for a terbium-doped yttrium aluminum garnet powder after annealing at 1100°C.

Synthetic diamond single crystals were grown by the thermal gradient method in a high-pressure apparatus in the presence of solvent catalysts (nickel, iron). Absorption, luminescence, and photoluminescence excitation measurements were performed in order to determine the nature of impurity-defect complexes in both as-grown crystals and crystals treated at high temperature (T≈2000–2200 K) and high pressure (P≈6.0–6.5 GPa). Different luminescence and absorption bands were assigned to impurity centers containing nitrogen and nickel atoms.

Optical properties of structurally perfect CuInSe2 single crystals were studied in the temperature range of 4.2–300 K with the use of photoluminescence, optical absorption, optical reflection, and wavelength-modulated optical reflection (WMOR). The intense lines of free excitons A (∼1.0414 eV) and B (∼1.0449 eV) with a half-width of ∼0.7 meV at 4.2 K are found to be related to two extrema of valence band split by a crystal field. The excitons emission line C (∼1.2779 eV) in WMOR spectra are related to a lower valence band split-off by spin-orbit interaction. Within the context of the quasi-cubic Hopfield model, the parameters of valence band splitting ΔCF=5.2 meV and ΔSO=234.7 meV defined by the crystal and spin-orbit interaction, respectively, are calculated. In the region of the fundamental absorption edge, the lines of bound excitons are found with a half-width ∼0.3 meV that is indicative of a high quality of grown CuInSe2 crystals.

Erbium-doped aluminum oxide films with embedded Si nanoparticles have been obtained by magnetron puttering of a composite (Al + Er2O3 + Si) target and subsequent electrochemical anodization at room temperature. The photoluminescence (PL) spectra of these films are measured in the temperature range 4.2–300 K. Efficient PL is observed at a wavelength of 1.54 μm without preliminary annealing of the samples, which indicates the possibility of activating Er3+ ions without any high-temperature treatment. The aluminum oxide films with embedded Si nanoparticles were observed to show stronger PL at a wavelength of 1.54 μm than similar films without Si nanoparticles. This effect can be explained by additional pumping of Er-based luminescence centers and energy transfer from the Si nanoparticles.

The luminescence and transmission of zinc diarsenide single crystals near the fundamental absorption edge have been investigated in the temperature range 4.2–300 K. Intense luminescence and absorption lines at 1.0384, 1.0488, and 1.0507 eV, referring to the ground state (n=1) and excited states (n=2, n=3) of a free exciton were observed at low temperatures. The free-exciton binding energy was found to be ∼13.9 meV on the basis of the hydrogen-like model and the direct band gap was found to be 1.0523, 1.0459, and 0.9795 eV at 4.2, 78, and 300 K, respectively.