EFFECT OF HYDROGEN ON PSEUDOMORPHIC ZNSE ONTO GAAS BY THE ALTERNATE GAS-SUPPLY OF DIMETHYLZINC AND DIMETHYLSELENIDE IN THE MOMBE SYSTEM

We investigated the pseudomorphic ZnSe on GaAs grown by the alternate gas source supply of dimethylzinc (DMZ) and dimethylselenide (DMSe) in the MOMBE system. We found through the in-situ RHEED monitoring that two-dimensional nucleation occurs from the early stage of growth if the GaAs substrates are pretreated by (NH4)2S(x) solution. A growth rate of about 0.95 ML (monomolecular layer) ZnSe per one operational cycle of gas source supply could be achieved on (NH4)2S(x)-pretreated GaAs substrates at 200-degrees-C under hydrogen gas exposure during growth. This result indicates that nearly complete atomic coverage is successfully proceeded in each step as a result of the termination of alkyl radicals adsorbed on the surface by hydrogen. Crystal qualities were much improved by both the substrate pretreatment and the hydrogen gas supply.