Confinement of light hole valence-band states in pseudomorphic InGaAs/Ga(Al)As quantum wells

Abstract

Pseudomorphic InGaAs/Ga(Al)As multiple quantum well structures with In content ranging from 7% to 25% and barriers with and without Al were grown by molecular beam epitaxy and investigated by optical absorption spectroscopy and photoluminescence excitation spectroscopy with linearly polarized light. A comparison of the absorption spectra between samples with and without Al content in the barriers shows that the light hole state is weakly bound in the InGaAs/GaAs quantum well at least for the lower In concentrations. Photoluminescence excitation with different linear polarization definitely distinguishes between the optical transitions of heavy or light hole to electron transitions. Several weak additional peaks appear in the spectra which are identified as forbidden optical transitions.