The effect of annealing substrates in vacuum, or a Cd-Zn atmosphere, was investigated at 600 to 800C. Fourier infra-red transform spectroscopy, cathodoluminescence and secondary ion mass spectroscopy measurements were performed out before and after annealing. The transmission spectrum, which was dominated by Cd-vacancy absorption and impurity absorption, was modified after annealing due to the filling-up of Cd vacancies and the out-diffusion of impurities. The cathodoluminescence measurements revealed impurity gettering around Te precipitates. The behaviour of Al, K, Na, Zn, Ca, Li, Cr, Fe, O, Br and Cl, as analyzed by means of secondary ion mass spectrometry, showed that non-metallic gaseous impurities diffused out of the substrate, and metallic impurities moved towards the surface, during annealing in Cd-Zn atmospheres. It was suggested that CdZnTe substrates should therefore be annealed before growing epitaxial layers.

Investigation of Effect of Thermal Annealing on CdZnTe Substrate using FTIR, SIMS and Cathodoluminescence. S.Sitharaman, M.Gautam, R.Raman, A.Kapoor, B.R.Chakraborty, Inderpal, F.R.Chavada, V.R.Prakash, S.C.Gupta: Proceedings of the SPIE, 2000, 3975, 112-5