Thermal etching of GaAs by hydrogen under arsenic overpressure

Abstract
GaAs was found to react directly with hydrogen at temperatures above 800 °C. This reaction resulted in etching of GaAs. An etching rate of 10–15 Å/min was observed after annealing at 900 °C in a H2/AsH3 ambient. On the other hand, no etching was observed after annealing in an Ar/AsH3 ambient. The etching rate was found to be proportional to the pressure of H2 to the 3/2 power. A smooth mirrorlike surface was obtained under excess As pressure, due to the resulting congruent loss of Ga and As. An Arrhenius plot of the etching rate gives an energy of 2.90 eV, which is in good agreement with the heat of evaporation of Ga, which indicates that the etching rate is determined by the rate of evaporation of Ga atoms at the surface.

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