Various dielectric caps were deposited on the GaAs/AlGaAs quantum-well structures followed by rapid thermal annealing to generate different degrees of interdiffusion. Deposition of a layer of GaxOy on top of these dielectric caps resulted in significant suppression of interdiffusion. In these samples, it was found that although the deposition of GaxOy and subsequent annealing caused additional injection of Ga into the SiO2 layer, Ga atoms were still able to out-diffuse from the GaAs quantum-well structure during annealing, to generate excess Ga vacancies. The suppression of interdiffusion with the presence of Ga vacancies was explained by the thermal stress effect which suppressed Ga vacancy diffusion during annealing. It suggests that GaxOy may therefore be used as a mask material in conjunction with other dielectric capping layers in order to control and selectively achieve impurity-free vacancy disordering.

Suppression of Interdiffusion in GaAs/AlGaAs Quantum-Well Structure Capped with Dielectric Films by Deposition of Gallium Oxide. L.Fu, J.Wong-Leung, P.N.K.Deenapanray, H.H.Tan, C.Jagadish, B.Gong, R.N.Lamb, R.M.Cohen, W.Reichert, L.V.Dao, M.Gal: Journal of Applied Physics, 2002, 92[7], 3579-83