Photoreflectance studies of lattice-matched and strained InGaAs/InAlAs single quantum wells

Lattice-matched and strained InxGa1−xAs/In0.52Al0.48As single quantum wells with x=0.53 and x=0.60 have been studied by the optical modulation technique of photoreflectance (PR) at room temperature. The measurements have allowed the observation of interband transitions from the heavy- and light-hole valence subbands to the conduction subbands. The PR data have been adjusted with a least-squares fit to the first-derivative functional form. The energetic positions of the optical transitions deduced from the fit have been compared with theoretical values obtained by an envelope function model calculation including strain effects. The best adjustment allowed the determination of the conduction-band offset parameter Qc which is found equal to 0.71±0.07 for the lattice-matched and strained compositions.