Monolayer control of chemical beam etching for regrowth

An etching process with real-time monitoring of each monolayer removed is demonstrated. The etching is accomplished by injecting AsCl ₃ or PCl₃ gas directly into the growth chamber at a temperature comparable to the typical growth temperature in the same system. This method allows instant switching between the etch and the growth modes. The etching rate of GaAs is insensitive to the substrate temperature, which is important for a reproducible etching technology. A roughening mechanism of the etched surface due to a lack of cation diffusion is identified. Using a pulse etching mode and a migration enhanced smoothing, mirror like morphology has been obtained in the etching of InP. A layer-by-layer etching process and a in-situ monitoring technique at atomic scale are essential for a true monolayer etching technology