-ORIENTED GaAs/AlGaAs AND InGaAs/GaAs QUANTUM WELL STRUCTURES FABRICATED BY MOVPE AND THEIR OPTICAL AND STRAIN-INDUCED PIEZOELECTRIC PROPERTIES

We report our recent results on the growth and properties of GaAs/AlGaAs and strained InGaAs/GaAs quantum well (QW) structures grown on (111)A GaAs substrates by atmospheric-pressure metalorganic vapor phase epitaxy. We have fabricated 25-period GaAs/AlGaAs multiquantum well structures with good crystal quality, high photoluminescence (PL) emission intensity and monolayer (ML) well width fluctuation. We also present the optical and piezoelectric properties of strained InGaAs/GaAs single quantum well structures grown on (111)A GaAs. Photoreflectance spectroscopy has been performed to analyze not only the excitonic transitions, but also the Franz-Keldysh oscillations to obtain the electric fields in the well and barriers, which are necessary to determine the actual QW potential profile and, thereby, to properly interpret the properties of the structures. A PL linewidth of 9.7 meV has been also achieved, which corresponds to a 1 ML interfacial roughness for an In0.14Ga0.86As well with a 40 Å width.