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

摘要

This paper presents the results of numerical simulation for 4 over bar 3mcrystals 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 CdxHg1-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 theta and phi turn out to be 1-3 degrees in the GaAs substrates and up to 8 degrees 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 chi(xyz)(omega) of the crystalline structure CdxHg1-xTe significantly exceed those of similar tensor components in CdTe and GaAs.