Photoluminescence and X-ray analysis of laser deposited II-VI thin films and multilayered structures

This work aims to determine the best buffer layer for the deposition of II-VI heterostructures on silicon. The results obtained from laser ablated films (1 μm thick) of CdSe, CdS and CdTe at different substrate temperatures are presented. A Nd:YaG laser (λ=532 nm) was used to ablate and deposit II-VI compounds in a vacuum chamber pumped down to 10/sup -6/ Torr. X-ray spectra were analysed and grain dimensions were calculated accordingly to Debye Sherrer formula. Photoluminescence experiments were carried out to study radiative transition and emission efficiency of the laser ablated films. A detailed study of linewidth and spectral position of the exciton line versus temperature T was performed. Broad PL bands due to extrinsic luminescence are present both in CdS and CdSe films. This PL feature is related to impurity levels localized in the energy gaps of the films. Recombination of donor acceptor pairs occurs and they are studied as a function of T and laser power.