Study of nature of lattice vibration variations depending on a spatial distribution of zinc on depth of Cd_xHg_(1-x)Te epitaxial layers grown on Cd_(1-x)Zn_yTe substrates

摘要

In this paper we report on the results of the study of optical properties of Cd_xHg_(1-x)Te epitaxial layers (EL), grown by the LPE method on Cd_(1-y)Zn_yTe substrates. The values of the band gap of the solid solution forming EL have been obtained from the optical absorption spectra (FTIR) taken in the spectral region of the interband absorption at step-by-step decrease of EL thickness as a result of a chemical etching. In bridge with it the distribution and character of variations in the intensity of lattice vibrations over the layer depth of Cd_xHg_(1-x)Te / CdZnTe epitaxial structures was investigated. Longitudinal and transverse lattice vibration frequencies of Cd_xHg_(1-x-y)Zn_yTe have been evaluated from the experimental spectra and compared with the theoretically calculated ones within a unit cell version of the random element isodisplacement model. From the comparing of the experimental and theoretical results it is possible to draw a conclusion that in immediate neighborhood of the Cd_xHg_(1-x)Te/Cd_(1-y)Zn_yTe interface the Cd_xHg_(1-x-y)Zn_yTe thin layer is formed under the certain conditions during the EL growth process, i.e., zinc atoms in given EL area is necessary to consider not as an impurity atoms, but as the components of the cationic sublattice.