X-ray analysis of GaAs surface reconstructions in H2 and N2 atmospheres

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Abstract
In this work, we demonstrate the first in situ study of GaAs using grazing incidence x-ray scattering during processing at 100 Torr prior to epitaxial film growth. Our results indicate that the native oxide is removed and a well-ordered surface reconstruction is established at temperatures as low as 500 °C in hydrogen. In contrast, no surface reconstruction is observed when the substrate is heated in nitrogen at temperatures as high as 585 °C while comparable heating in hydrogen causes surface degradation in the form of liquid Ga droplets. These results suggest that a chemically induced surface transformation occurs rather than oxide evaporation during thermal treatment.