Optical Characterization of Pseudomorphic GaAsSb/GaAs-Based Quantum Well Structures Grown by Metal Organic Vapor Phase Epitaxy

Optical characterization of pseudomorphic GaAsSb/GaAs-based quantum well structures grown by metal organic vapor phase epitaxy is carried out by using photoreflectance (PR), surface photovoltage spectroscopy (SPS) and photoluminescence (PL) techniques. The samples investigated include a strained GaAs0.64Sb0.36/GaAs and a strain-compensated GaAs0.64Sb0.36/GaAs/GaAs0.79P0.21 triple quantum well (TQW) structures. For GaAsSb/GaAs TQW, only a very weak PR feature is observed in the vicinity of fundamental transition and larger blue shifts of the peak positions of PL features with increasing of excitation power density has been attributed to a weakly type-II heterojunction formed between GaAsSb and GaAs. The PR and SPS spectra of GaAsSb/GaAs/GaAsP TQW display a series of features originated from interband transitions which is a typical characteristic of type-I QW structure. The results indicate that the energy band of strain-compensated QW structures is significantly influenced by the inserted GaAsP layers, which changes the weakly type-II to a type-I structure. The strain-compensated GaAsSb/GaAs/GaAsP QWs have a larger overlap integral and hence a higher transition probability, providing a possibility for fabricating high efficiency near infrared laser diodes.