Dimensional quantization in GaAs/Al$_x$Ga$_{1-x}$As heterostructures according to photoreflection spectroscopy data

By photoreflection spectroscopy, the epitaxial GaAs/Al$_x$Ga$_{1-x}$As heterostructures with quantum well widths of 10, 20, and 30 nm were studied. At room temperature, in the photoreflection spectra, alongside with lines in the regions of the GaAs (1.4 eV) and Al$_x$Ga$_{1-x}$As (1.74 eV) fundamental transitions, spectral features related to dimensional quantization in the well and to the splitting of the valence band into subbands of heavy and light holes were observed. The experimental level energies agreed well with those calculated under the envelope wave function model.