Photoluminescence study of radiative transitions in ZnTe bulk crystals

This paper focuses on photoluminescence (PL) and selective photoluminescence (SPL) of ZnTe bulk crystals grown by the cold traveling heater method. The crystals exhibit a PL response with a much more intense excitonic zone than the one due to free-to-bound and donor-acceptor bands, denoting a good sample quality. In particular, we have investigated the Y-1 and Y-2 peaks which, in epitaxial layers, have usually been associated with structural defects. On bulk samples they have not been detected so far because of different masked mechanisms. SPL measurements show that the electrons are the most likely involved carriers for this emission. Additionally, the analysis of the PL variation with temperature for the Y-2 peak yields a thermal activation energy of 36 meV. This activation energy and the involved carriers support the fact that these peaks and those appearing at the same energy in epitaxial layers are due to different mechanisms. Finally an emission band in the range of 625-680 nm is analyzed and compared with other results previously reported in the low-energy region. (C) 1998 Elsevier Science B.V. All rights reserved.