OPTICAL-ABSORPTION TAILS IN CD0.97ZN0.03TE AND CDS AT ELEVATED-TEMPERATURES

Low energy optical absorption in Cd0.97Zn0.03Te and CdS has been studi ed at temperatures up to 1014 and 1161 K, respectively, by measurement s of the incandescence spectra of wafers of both materials. Exponentia l absorption (Urbach) tails were observed, characterised by a spreadin g energy which increased exponentially with increasing temperature. Th is contrasts with the inverse temperature dependence widely assumed to be the high temperature limit for this parameter. It may be that defe cts are dominating the absorption tail at high temperatures in these s amples, rather than phonon induced electric fields. (C) 1998 Elsevier Science B.V. All rights reserved.