REDUCTION OF INTERFACE CONTAMINATION IN REGROWN GAAS ON ALGAAS USING A NOVEL 2-STEP HCL-GAS ETCHING PROCESS

A two-step HCl gas etching process followed by regrowth using metalorg anic chemical vapor deposition (MOCVD) has been developed. Two-step HC l gas etching involves a low-temperature HCl gas treatment (LTT) follo wed by high-temperature HCl gas etching. Upon using this process, no c arbon accumulation was detected at the interface between the etched Al 0.48Ga0.52As layer and the regrown GaAs layer. Oxygen accumulation at the regrowth interface was reduced to less than one fifth by applying LTT. The dislocation density in the regrown GaAs layer was shown to be comparable to that found in the usual GaAs homoepitaxial layer. The r esults of carrier lifetime measurements in GaAs/AlGaAs regrown double- hetero (DH) structures indicated the excellent quality of both the reg rown GaAs layer and the regrowth interface. It was thus demonstrated t hat by using this newly developed two-step HCl gas etching process, th e crystalline quality of a regrown GaAs layer on AlGaAs can be suffici ently improved to be used as an active layer of optical devices.