Thermal removal of surface carbon from GaAs substrate used in molecular beam epitaxy

Abstract

Chemical etching of GaAs substrates followed by deionized-water rinsing and loading to a molecular beam epitaxy chamber always leaves carbon contamination on the substrate surface. Auger analysis shows that an extensive exposure of the substrate to the Auger beam, especially during the initial substrate heating process below ∠350 °C, strengthens the bonding between surface carbon and the substrate which makes subsequent thermal removal of surface carbon above ∠350 °C very difficult. The effect of substrate surface cleanliness on the initial growth of GaAs is also studied using high-energy electron diffraction.