The properties of native oxides on different chemically etched GaAs (100) surfaces were investigated by Auger electron spectroscopy (AES) and x‐ray photoelectron spectroscopy (XPS) analyses. The thickness and composition of native oxides depended not only on the kind but also on the sequence of chemical solutions used, and continuous etching was the most effective method for reducing surface oxide. It was also found that the unetched (just polished) wafer had a Ga‐rich surface, the H 2 SO 4 mixture‐etched wafer had an As rich surface, and the NaOH mixture‐etched and the continuously etched wafer had a nearly stoichiometric surface. All the surfaces of measured wafers were As‐oxide rich. To understand the mechanism of chemical etching and the surface state of differently treated wafers, AES data were combined with XPS data. Thus the surface state was estimated and a model for native oxidation process was proposed. These results were explained by the pH‐dependent solubility of Ga, As, and their oxides, and the reactivity of As in atmosphere after etching.
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Yoon et al. (1992) studied this question.