STRUCTURAL-PROPERTIES AND PHOTOLUMINESCENCE STUDY OF CDSE SI EPILAYERS DEPOSITED BY LASER-ABLATION/

Structural and optical characterization of CdSe thin films deposited b y laser ablation technique on silicon (100)- and (111)-oriented substr ates are reported. The effect of the substrate orientation on the grow th and luminescence features of the two types of epilayers are investi gated. Photoluminescence spectra of CdSe films measured from 10 up to 300 K and as a function of the laser excitation intensity give detaile d information on the extrinsic levels localized in the forbidden gap. Temperature dependence of the energy of the n = 1 exciton line has bee n fitted by the Varshni's equation and by an expression containing the Bose-Einstein occupation factor for phonons. Parameters related to th e electron-phonon interaction have been obtained. Temperature dependen ce of the broadening of exciton linewidth has been studied in terms of an expression containing both exciton-optical phonon and exciton-acou stic phonons coupling constants. Evaluated fitting parameters have sho wn the dominant contribution of optical phonons in mechanism of the ex citon line broadening. (C) 1998 American Institute of Physics.