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 cyclotron resonance hydrogen plasma to remove the native oxides, followed by a very brief Cl2 chemical etching of GaAs to further reduce C and Si residues, 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 detection limit. The as-processed GaAs surface, a Ga-stabilized reconstructed (4 X 6), is atomically smooth, and is as clean as a surface of freshly grown GaAs epilayers.