Study of the vibrational states of CdTe and CdHgTe lattices under conditions of the adsorption of ammonia and carbon dioxide

A comparative analysis of the Raman spectra of CdTe and Cd$_{0.2}$Hg$_{0.8}$Te crystals stored in air, ammonia NH$_3$, and carbon dioxide CO$_2$ is performed. It is established that the chemical adsorption of gases causes deformation of the surface of the semiconductors, the signal shape of recombination luminescence varies and hidden vibrational modes of acoustic and optical phonons appear. The variation in the spectrum of lattice vibrations confirms the occurrence of the inverse absorption piezoelectric effect in A$^X$B$^{8-X}$ materials, particularly CdTe and Cd$_{0.2}$Hg$_{0.8}$Te.