Initial evaporation rates from GaAs during rapid thermal processing

Abstract

The initial rates of evaporation of Ga and As from the surface of single-crystal GaAs during rapid thermal processing (RTP) have been determined in the temperature range from 600 to 750 °C. Absolute vaporization rates for capless annealing of GaAs were measured by collecting the evaporated species on a copper film, which condenses 50%–100% of the evaporated material. Initial evaporation rates during RTP are shown to be in agreement with the maximum predicted rates based on the Hertz–Knudsen equation. In a second set of experiments, the preferential loss of arsenic for GaAs-GaAs proximity annealing was measured using ion channeling. All experimental results are interpreted in terms of a model which we develop for capless and proximity annealing based on the kinetic theory of gases.