TIME-RESOLVED PHOTOLUMINESCENCE STUDY ON A HETERO INTERFACE FORMED BYDIRECT REGROWTH OF GAAS ON AN AL0.3GA0.7AS SURFACE PREPARED BY AN IN-SITU HCL-GAS ETCHING PROCESS

We have studied the quality of Al0.3Ga0.7/GaAs/Al0.3Ga0.7 double heter o (DH) structures, whose lower hetero interface is formed by regrowing GaAs directly on an etched Al0.3Ga0.7As surface, The Al0.3Ga0.7As sur face is prepared by two-step in situ etching, which is comprised of a low temperature treatment and high temperature etching with HCl gas, j ust prior to the regrowth by metalorganic chemical vapor deposition. T ime resolved photoluminescence measurements have revealed that the opt ical quality of the region DH structure is significantly improved by a pplying the two-step HCl gas etching process compared to the wet proce ssed one. The PL decay curve of the in situ processed sample, however, shows a relatively shorter carrier lifetime than that of the continuo usly grown DH sample. An interface reconstruction velocity of 6.8 x 10 (3) cm/s is obtained for the in situ processed AlGaAs interface. This value for the AlGaAs with a high Al content is comparable to the best results for the in situ processed GaAs and InGaAs surfaces reported so far, The relatively high recombination velocity compared to continuou sly grown interfaces is mainly due to residual oxygen at the irt situ processed, interface of concentrations as low as 2.2 x 10(11) cm(-2).