A study was made of the thermal stability of Al2O3 and MgO on ZnO films by using photoluminescence. It was found that the near interfacial regions of both Al2O3/ZnO and MgO/ZnO degrade significantly upon thermal annealing, which were evident by the decrease in band-edge emission and the increase in deep-level emissions. By using secondary ion mass spectroscopy and diffusion model, the dependence of luminescence on annealing temperature and duration could be simulated and the degradation of oxide/ZnO could be attributed to the out-diffusion of Zn into the oxide layer from ZnO. The activation energies and diffusion constants for the diffusion process occurring in these two systems were determined accordingly.

Study of Interfacial Diffusion in Al2O3/ZnO and MgO/ZnO Heterostructures. Wang, R.S., Ong, H.C.: Journal of Applied Physics, 2008, 104[1], 016108