INFLUENCE OF THE COMPOSITION OF THE RADIO-FREQUENCY SPUTTERING ATMOSPHERE ON THE DENSITY OF STATES AND INTERBAND LIGHT ABSORPTION IN THIN Y2O3 FILMS

The long-wavelength edge of the fundamental absorption band of thin Y2O3 films obtained by radiofrequency ion-plasma sputtering is investigated. The edge of interband absorption after annealing of the films in an atmosphere of argon, oxygen, or a mixture of these gases is shown to be approximated well by the Urbach empirical rule. Diffractograms of the obtained films were studied and a model of a heavily doped or defective semiconductor in the quasi-classical approximation was used to analyze the experimental results. This model allows determining the radius of the basic electronic state, the screening radius, and the rootmean-square potential depending on the sputtering atmosphere.

Effect of Electronic Correlations on the Electronic Structure, Magnetic and Optical Properties of the Ternary RCuGe Compounds with R = Tb, Dy, Ho, Er

In this study, the ab initio and experimental results for RCuGe ternary intermetallics were reported for R = Tb, Dy, Ho, Er. Our theoretical calculations of the electronic structure, employing local spin density approximation accounting for electron–electron correlations in the 4f shell of Tb, Dy, Ho, Er ions were carried in DFT+U method. The optical properties of the RCuGe ternary compounds were studied at a broad range of wavelengths. The spectral and electronic characteristics were obtained. The theoretical electron densities of states were taken to interpret the experimental energy dependencies of the experimental optical conductivity in the interband light–absorption region. From the band calculations, the 4f shell of the rare-earth ions was shown to provide the major contribution to the electronic structure, magnetic and optical properties of the RCuGe intermetallics. The accounting for electron–electron correlations in Tb, Dy, Ho, Er resulted in a good agreement between the calculated and experimental magnetic and optical characteristics.

Оптические свойства соединений YFe-=SUB=-2-=/SUB=- и TbFe-=SUB=-2-=/SUB=-

Ellipsometric investigation of the optical properties of YFe2 and TbFe2 intermetalic compounds have been carried out in wavelength range of 0.22 –15 μm. A number of electronic and spectral characteristic was determined. Nature of interband light absorption in these materials is discussed on base of comparative analyses of experimental and theoretical optical conductivity spectra. Experimental optical conductivities of the compounds are shown to conform qualitatively to spectra calculated from densities of electronic states in the region of quantum electron transitions.

Coefficient of Interband Light Absorption by InAs/GaхIn1-хAs Quantum Dot Superlattice at Low Temperatures

In the paper the InAs/GaxIn1-xAs superlattice system of small size cubic QDs (10 nm) has been considered. Dispersion relations for electron and hole subbands have been calculated for superlattices of different dimensionality. The dependences of the interband absorption coefficient on light frequency, quantum dot size and interdot distance have been researched.It is shown, that the dimension of the superlattice has influence on the shape of the absorption bands and the increasingof the distance between quantum dots is followed by narrowing of the absorption peaks for all three superlatticetypes.