Se profiles in CST films formed by annealing CdTe/CdSe bi-layers

Se profiles in CST (CdSe X Te 1-x ) films formed by annealing CdTe/CdSe bilayers has been studied using transmission electron microscopy (TEM) and photoluminescence (PL). The effect of CdSe layer thickness and CdCl 2 annealing conditions on the alloy layer were investigated. The CdSe thickness was varied from 75 to 1,500 Å. All “thick” films (CdSe Å300 Å) exhibited smaller grain structure at the interface compared to the “thin” films (CdSe 75-30 Å), which exhibited large columnar grains that extended through the CST/CdTe film thickness. The alloy layer for “thick” CdSe films appeared as a bilayer with two CST compositions: Se-rich and Te-rich. Photoluminescence measurements revealed Se related defects in the films with thicker CdSe (1,000 and 1,500 Å). The Se compositional profile was found to be greatly dependent on the CdSe thickness and CdCl 2 heat treatment conditions. The formation of voids at the interface for large CdSe thicknesses suggests that this approach may be only suitable for the formation of relatively low Se content CST films.