Study of substrate diffusion in epitaxial n-type CdSe films grown on GaAs (001) by pulsed laser ablation

摘要

N-type CdSe films with thicknesses of 470--630 nm were grown on (001) and 2(degree)-miscut GaAs wafers by ArF (193 nm) pulsed laser ablation of stoichiometric CdSe targets at platen temperatures (T(sub p)) of 250--425 C in vacuum and ambient Ar gas. Film-substrate interdiffusion was studied with Auger depth profiling, as well as energy dispersive x-ray fluorescent spectroscopy (EDS). Both techniques showed that extensive interdiffusion took place at the film-substrate interface for CdSe films grown at T(sub p) (ge) 355 C but was greatly reduced at T(sub p) = 250 C. Tilting the substrate to be approximately parallel to the ablation plume as well as decreasing the ambient gas pressure also reduced film-substrate interdiffusion.