Surface Science

Chlorine chemisorption on and the onset of etching of cleaved GaAs(110) at room temperature

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Cleaved GaAs(110) surfaces are exposed to Cl2 at room temperature and then examined by surface-sensitive soft X-ray photoelectron spectroscopy of the valence, As 3d, and Ga 3d levels. The results show that AsCl, AsCl2, and GaCl all form on the surface after small exposures, while GaCl2 forms after larger exposures. A detailed analysis of the data shows that, after the initial Cl2 exposures, Ga and As atoms are anisotropically etched from the surface, with Ga being removed first. As a consequence of the etching process, a number of Ga and As atoms are stabilized in sub-surface three-fold sites. After larger exposures, the surface is considerably roughened. © 1994.