Express Characterization of Crystalline Perfection of CdxHg1−xTe Structures by Reflection Second Harmonic Generation of Probing Radiation.

This paper presents the results of numerical simulation for 4 ¯ 3 m crystals and experimental results for azimuthal angular dependences of polarization components of a second harmonic signal reflected from GaAs(013) substrates, CdTe/ZnTe/GaAs buffer layers, and Cd_xHg_1−xTe/CdTe/ZnTe/GaAs structures, sequentially grown on these substrates with normal incidence of probing laser radiation on the sample and azimuthal rotation of its polarization plane. It is revealed from investigating the GaAs(013) substrates and CdTe/ZnTe/GaAs buffer layers that deviations from the base cut (013) relative to angles θ and ϕ turn out to be 1–3° in the GaAs substrates and up to 8° in the CdTe/ZnTe/GaAs buffer layers. The observed asymmetry of the minima of angular experimental dependences of the second harmonic signal in the GaAs substrates is related to stresses. It is assumed on the basis of the experimental data that the values of the components of the nonlinear susceptibility tensor χ_xyz(ω) of the crystalline structure Cd_xHg_1−xTe significantly exceed those of similar tensor components in CdTe and GaAs. [ABSTRACT FROM AUTHOR]