Reduced nonradiative recombination in etched/regrown AlGaAs/GaAs structures fabricated by in situ processing

Abstract

Effectiveness of in situ processing, which combines Cl2 gas etching with subsequent molecular beam epitaxy regrowth in an ultrahigh vacuum environment, is quantitatively evaluated with nonradiative carrier recombination velocity, S, of etched/regrown AlGaAs/GaAs heterointerfaces. When AlGaAs is in situ regrown on Cl2 gas-etched flat GaAs surface, the S value is as low as 1.3×103 cm/s. This value is lower than that of air-exposed/regrown (or ex situ processed) interfaces, thus representing the essential superiority of in situ processing over ex situ. Buried GaAs/AlGaAs multiquantum-well (MQW) mesa-stripes are also fabricated by in situ Cl2 gas-etching/regrowth. The S value at the MQW mesa-sidewall regrown with AlGaAs is 6.0×103 cm/s, which is reduced by more than one order of magnitude from that of a nonburied case.