Reduction of interface contamination in regrown GaAs on AlGaAs using a novel two-step HCl gas etching process

Abstract

A two-step HCl gas etching process followed by regrowth using metalorganic chemical vapor deposition (MOCVD) has been developed. Two-step HCl gas etching involves a low-temperature HCl gas treatment (LTT) followed by high-temperature HCl gas etching. Upon using this process, no carbon accumulation was detected at the interface between the etched Al0.48Ga0.52As 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 results of carrier lifetime measurements in GaAsAlGaAs regrown double-hetero (DH) structures indicated the excellent quality of both the regrown GaAs layer and the regrowth interface. It was thus demonstrated that by using this newly developed two-step HCl gas etching process, the crystalline quality of a regrown GaAs layer on AlGaAs can be sufficiently improved to be used as an active layer of optical devices.