Time-Resolved Photoluminescence Study on a Hetero Interface Formed by Direct Regrowth of GaAs on an Al_<0.3>Ga_<0.7>As Surface Prepared by an In Situ HCl Gas Etching Process

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We have studied the quality of Al_<0.3>Ga_<0.7>/GaAs/Al_<0.3>Ga_<0.7> double hetero (DH) structures, whose lower hetero interface is formed by regrowing GaAs directly on an etched Al_<0.3>Ga_<0.7> surface. The Al_<0.3>Ga_<0.7> surface is prepared by two-step in situ etching, which is comprised of a low temperature treatment and high temperature etching with HCl gas, just prior to the regrowth by metalorganic chemical vapor deposition. Time resolved photoluminescence measurements have revealed that the optical quality of the regrown DH structure is significantly improved by applying the two-step HCl gas etching process compared to the wet processed one. The PL decay curve of the in situ processed sample, however, shows a relatively shorter carrier lifetime than that of the continuously grown DH sample. An interface recombination velocity of 6.8×10^3 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 continuously grown interfaces is mainly due to residual oxygen at the in situ processed interface of concentrations as low as 2.2×10^<11> cm^<-2>.
社団法人応用物理学会の論文
1997-10-15