X-RAY-ANALYSIS OF GAAS SURFACE RECONSTRUCTIONS IN H2 AND N2 ATMOSPHERES

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.