A layer of SiO2, deposited by sputtering, was used as a diffusion source for Si impurities, as well as a source of Ga vacancies which enhanced impurity diffusion and permitted reductions to be made in the required annealing temperatures and times. A self-aligned native oxide of an AlGaAs cladding layer was used to form a Zn diffusion mask and dielectric layer.

R.S.Burton, T.E.Schlesinger, D.J.Holmgren, S.C.Smith, R.D.Burnham: Journal of Applied Physics, 1993, 73[4], 2015-8