Dissolution of crystalline gallium arsenide in aqueous solutions containing complexing agents

Crystalline gallium arsenide (GaAs) was found to dissolve in an aqueous solution containing the inorganic anions, chloride, sulfate, bicarbonate, monohydrogen phosphate, and dihydrogen phosphate, and the organic anions, acetate and citrate. The aqueous solution was made up to resemble lung fluid (Gamble solution) and was maintained at a pH of 7.4. The concentrations of arsenic (As) and gallium (Ga) in solution and the As-GA ratio on the surface of the GaAs increased continuously as the time of contact with the aqueous solution increased. X-ray photoelectron spectroscopic studies of the GaAs surface, at various time intervals, showed that As migrated to the surface and was oxidized to a species resembling As2O3 and, finally, was dissolved. The zinc present in the crystalline GaAs also migrated to the surface.