Optical characterization of (GaIn)(NAs)/GaAs MQW structures

(GaIn)(NAs)/GaAs multiple quantum well (MQW) structures with high structura l perfection as determined from high-resolution x-ray diffraction (XRD) ana lysis have been deposited by low-temperature metal organic vapor phase epit axy (MOVPE) at 525 degrees C using triethylgallium (TEGa) and trimethylindi um (TMIn) in combination with I,l-dimethylhydrazine (UDMHy) and tertiarybut ylarsine (TBAs). The optical characteristics of as-grown MQW structures as a function of quaternary composition and of well width are established by P L spectroscopy at 300 K. With increasing N-content a reduction in PL effici ency and an increase in PL linewidth is observed. This behavior might be co rrelated to an increase in defect density with increasing N-content and/or to a bandstructure effect in this novel material system. For an increase in In-concentration the tendency for a reduction in the extreme bowing of the band gap is detected. Strong quantization effects are observed for well wi dths below 5 nm only in this novel MQW system, which indicates significantl y larger electron masses as compared to N-free (GaIn)As.