Photoreflectance Studies of InGaAs/GaAs/AlGaAs Single Quantum Well Laser Structures

We report on photoreflectance investigations of strained-layer In$\text{}_{0.2}$Ga$\text{}_{0.8}$As/GaAs/Al$\text{}_{0.3}$Ga$\text{}_{0.7}$As single quantum well laser structures grown by molecular beam epitaxy. All the observed photoreflectance spectral features were assigned to the e-hh transitions with Δn=0. The transition energies were determined and compared to their values calculated within the envelope function approximation. Assuming that one third of the total strain in the central In$\text{}_{0.2}$Ga$\text{}_{0.8}$As layer is relaxed by biaxial deformation of surrounding thin GaAs layers, it is possible to explain reasonably the results of our photoreflectance experiment.