Data were presented which showed that the native oxide that could form on AlxGa1-xAs confining layers (where x was greater than 0.7) on AlyGa1-yAs/AlzGa1-zAs superlattices or quantum-well heterostructures (where y was greater than z) served as an effective barrier to Zn impurity diffusion. It thus impeded impurity-induced layer disordering. High-quality native oxide was produced by the conversion of high x-value AlxGa1-xAs confining layers (which could be grown on a variety of heterostructures) via H2O vapor oxidation (at temperatures of more than 400C) in N2 carrier gas.

J.M.Dallesasse, N.Holonyak, N.El-Zein, T.A.Richard, F.A.Kish, A.R.Sugg, R.D.Burnham, S.C.Smith: Applied Physics Letters, 1991, 58[9], 974-6