Lattice-Mismatch Enhanced Diffusion at a ZnSe/GaAs Interface - Increase of Thermal Stability in a Lattice-Matching System

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Abstract
ZnSe/GaAs interface diffusion, especially at an elevated temperature, was investigated. For ZnSe films of which stoichiometry was not completely maintained at the interface, the enhancement of Zn diffusion into GaAs was observed with an increase of film thickness. With preheating of GaAs substrates prior to growth, ZnSe films are stably deposited on GaAs. However, for thick ZnSe films of 7200 Å, the original n-ZnSe/n-GaAs interface turned out to be converted to p-type at the interface after thermal annealing at 650°C for three hours. These interface diffusions which depend on the film thickness are estimated to be related with the misfit-induced lattice relaxation caused above a critical thickness. This hypothesis was confirmed by the extreme thermal stability found in the lattice-matched ZnS0.06Se0.94/GaAs interface.