Crystallographic properties of the HgCdTe layers grown by MBE on CdZnTe(211)B substrates

Abstract

A review of the specificity of the growth Hg_1-xCd_xTe layers by molecular beam epitaxy (MBE) and results of experimental studies of several Hg_1-xCd_xTe layers grown on Cd_yZn_1-yTe (CZT) substrates are presented. It is well known that the performance of Hg_1-xCd_xTe -based detectors strongly depends on the substrate material and its orientation. CZT substrates are among the most commonly used due to their very good lattice match with Hg1-xCdxTe absorber material with different Cd content. In the present work, the authors focused on optimizing the MBE growth parameters in order to obtain the best possible crystalline quality of Hg_1-xCd_xTe layers grown on CZT substrates with (211)B orientation, in particular in terms of minimizing the number of defects. Experimental results of the selected structures showed that the obtained undoped Hg_1-xCd_xTe layers of different x have high crystallographic and optical quality, as well as good surface morphology. In particular, high-resolution X-ray diffraction (HRXRD) measurements and their analysis showed that the best structure has a full width at half maximum of rocking curve (FWHM_RC) as low as 21.5 arcsec, and that the intensity distribution of diffraction peaks does not indicate the influence of mosaicisity and dislocation density.