Substrate chemical etching prior to molecular-beam epitaxy: An x-ray photoelectron spectroscopy study of GaAs {001} surfaces etched by the H2SO4-H2O2-H2O solution

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Abstract
X‐ray photoelectron spectroscopy has been performed in order to investigate the effects of the chemical etching of GaAs {001} surfaces by the H2SO4/H2O2/H2O solution used following the procedure currently practiced in the molecular‐beam‐epitaxy technique. It is demonstrated that, in contrast to what is generally believed, rinsing in running deionized water after etching does not produce any passivating oxide film on the surface. The surface‐oxidized phases are only due to the sample manipulation in air after etching. This oxidation process is enhanced by the sample heating for indium soldering on the sample holder. It is shown that the surface‐oxidized phases can be avoided by handling the sample under an inert atmosphere. Results of thermal desorption of the surface‐oxidized phases are also given.