Annealing effects on Cd0.96Zn0.04Te crystals with Te inclusions probed by photoluminescence spectroscopy

With effectively improved spectral resolution and signal-to-noise ratio, PL features are well resolved in the Te- and Cd-rich Cd0.96Zn0.04Te crystals and ascribed to the neutral donor-bound exciton ((DX)-X-0), acceptor-bound exciton (A(0)X), A-center, and deep donor-acceptor pair. A detailed analysis indicates that (i) Cd pressure annealing drives the Te inclusions to the surface region of the crystal, destroys the inclusions by excess Cd atoms, and releases abundant donor-like and acceptor-like impurities; (ii) the PL features of the deep energy levels at 1.30-1.55 eV originate in the A-center consisting Cd vacancy and one type shallow donor, and the PL feature at 1.474 eV is the so-called SA luminescence of a donor-acceptor transition between an A center and another shallow donor. A quantitative description of the recombination scheme is established, and by which the effects of the annealing are clarified. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim