SURFACE-REACTIONS OF DIMETHYLAMINOARSINE DURING MOMBE OF GAAS

We present in-situ mass spectroscopy studies of surface reactions of dimethylaminoarsine and tertiarybutylarsine under metalorganic molecular beam epitaxy conditions. The results show that the thermal decomposition of dimethylaminoarsine is completed at 450-degrees-C with the major products being dimethylamine, hydrogen, aziridine and N-methylmethyleneimine. In contrast, tertiarybutylarsine is not fully decomposed even at 550-degrees-C. Co-dosing experiments with trimethylgallium and deuterium labeled trimethylgallium (Ga(CD3)3) show methane and methylarsenic to be major reaction products in addition to nitrogen containing species, specifically aziridine, methylmethyleneimine and dimethylamine. No trimethylamine is detected as a surface reaction product. The generation of methane and methylarsenic from the surface is proposed as a possible mechanism for the reduced carbon incorporation reported for molecular beam epitaxy growth of GaAs with dimethylaminoarsine.