SELECTIVE METALORGANIC CHEMICAL-VAPOR-DEPOSITION GROWTH OF GAAS ON ALGAAS COMBINED WITH IN-SITU HCL-GAS ETCHING

Selective metalorganic chemical vapor deposition (MOCVD) growth of GaAs on Al0.48Ga0.52As combined with in situ HCI gas etching was investigated. In the case that AlGaAs surface was oxidized prior to the in situ HCI gas etching, accumulation of both oxygen and chlorine were found at the GaAs/AlGaAs regrowth interface. The dislocation density in the regrown GaAs layer was also increased to over 1 x 10(8) cm-2 by the existence of the accumulated oxygen and chlorine. The high quality GaAs regrown layer on AlGaAs with low dislocation density of 4.2 x 10(4) cm-2 was obtained by using the GaAs cap layer to prevent the oxidation of AlGaAs surface, and by the adequate AsH3 flow rate during the HCI gas etching. It was also found that the complete removal of surface oxide on the GaAs cap layer just prior to the HCl gas etching makes perfect reduction of the accumulation of oxygen and chlorine at the GaAs/AlGaAs regrowth interface. The buried ridge waveguide laser fabrication was successfully demonstrated by the selective MOCVD growth combined with the in situ HCl gas etching.