Temperature dependence of the optical transitions in CdTe thin film - Investigation with photoresponse spectra

The CdTe thin films have been prepared by electrochemical method from a bat h solution containing cadmium sulfate and tellurium dioxide. Schottky devic es of the type Au/CdTe were prepared and the spectral response of the devic e has been investigated. The direct and indirect transitions in the 1.3-1.6 eV region were calculated from the normalized spectral response data. The temperature dependence of the band gap have been investigated and correlate d with the theory. The band gap of CdTe at absolute zero temperature is est imated as 1.61 eV and that the rate of change of E-g with temperature is ca lculated as -0.4meV/K. The 1.407eV indirect transition involves a trap leve l near the conduction band edge. The indirect transition also exhibits temp erature dependence. (C) 2000 Elsevier Science B.V. All rights reserved.