Elevated Temperature Reactive Ion Etching of GaAs and AIGaAs in C2H6 / H2

The temperature dependence of etch rate, surface morphology and atomic composition, and depth of hydrogen passivation of Si dopants in n-type GaAs and AIGaAs has been measured for reactive ion etching in C2H6 /H2. The etching of GaAs shows an increase of a factor of two between 150 and 250°C, decreasing at higher temperatures, while there is no temperature dependence for the etch rate of AlGaAs over the range 50-350°C. The As-to-Ga ratio in the nearsurface region of GaAs remains unchanged over the whole temperature range investigated and there is no polymer deposition. The etched surface morphology is smooth for both GaAs and AIGaAs for all temperatures while the depth of Si dopant passivation by hydrogen shows an increase with increasing substrate temperature during the etching treatment.