Detection Sensitivities of Photoluminescence Spectroscopy and Polariscopy to Residual Strains in a (110)-oriented ZnTe Single Crystal: Explore of Strain-sensitivity Inspection Techniques

We demonstrate that sensitivity of polariscopy to residual strains is higher than that of the photoluminescence spectroscopy in a (110)-oriented ZnTe single crystal. We carried out x-ray topography and micro θ-2θ x-ray diffraction measurements in order to thoroughly clarify the crystal quality connecting with the residual strains. The two x-ray analyses revealed that there is misalignment from the [110] direction in some regions of the present sample. We found the following main results: The polariscopic analysis detects the residual strain formed by the misalignment, whereas the photoluminescence measurement cannot detect the residual strain. Thus, we conclude that polariscopy has the sensitivity to the residual strain higher than that of the photoluminescence spectroscopy. We confirmed that the polariscopic analysis can detect the internal strain less than 0.02% in the ZnTe crystal. In addition, we discuss the applicability of polariscopic analysis to other compound semiconductors.