Electronic parameters and interfacial properties ofGaAs/AlxGa1−xAsmultiquantum wells grown on(111)AGaAs by metalorganic vapor phase epitaxy

We report a comprehensive study of the optical and interfacial properties of GaAs/Al x Ga 1 - x As multiquantum wells grown on (111)A GaAs substrates by metalorganic vapor phase epitaxy which allowed the determination of the electronic parameters appropriate for such quantum wells. High-resolution x-ray diffractometry studies indicate an excellent crystal quality and good periodicity for the multiquantum wells and provided their structural parameters accurately. The photoreflectance spectra exhibit all the allowed and almost all the weakly allowed optical transitions between the confined hole and electron states. From an analysis of the photoreflectance spectra it is shown that the quantum well interfaces have an abruptness better than ′ 1 ML. Photoluminescence spectroscopy was also performed to evaluate independently the roughness of the interfaces and multiquantum well period reproducibility. For a 25-period multiquantum well structure with a well width of 55 A, a photoluminescence linewidth of 12.5 meV, which corresponds to a combined well-width fluctuation and interface roughness of less than ′ 1 monolayer over the 25 periods, proves the achievement of heterointerfaces with excellent interfacial quality. From a detailed analysis of the high-order transitions observed in the photoreflectance spectra we determined key quantum well electronic parameters, such as, the heavy-hole valence-band offset Q v =0.33′0.02, the transverse GaAs heavy-hole effective mass m h h =(0.95′0.02)m 0 , and the light-hole effective mass m l A =0.08m 0 in (111) directions, for (111)-oriented GhAs/Al x Ga 1 - x As quantum well structures.