REMOVAL OF GAAS SURFACE CONTAMINANTS USING H2 ELECTRON-CYCLOTRON-RESONANCE PLASMA TREATMENT FOLLOWED BY CL2 CHEMICAL ETCHING

We report a novel dry process to remove the surface contaminants C, Si , and 0 from GaAs substrates. This method utilizes an electron cyclotr on resonance hydrogen plasma to remove the native oxides, followed by a very brief Cl2 chemical etching of GaAs to further reduce C and Si r esidues, and a final vacuum anneal. Characterization by secondary ion- mass spectrometry (SIMS) typically reveals the removal of C, Si, and O at the overgrown/processed interface to the levels below the SIMS det ection limit. The as-processed GaAs surface, a Ga-stabilized reconstru cted (4 X 6), is atomically smooth, and is as clean as a surface of fr eshly grown GaAs epilayers.