Photoluminescence excitation spectroscopy of as-grown and chemically released ${\mathrm{In}}_{0.05}$${\mathrm{Ga}}_{0.95}$As/GaAs quantum wells

Chemically released and as-grown ${\mathrm{In}}_{0.05}$${\mathrm{Ga}}_{0.95}$As/GaAs single quantum wells were studied with use of low-temperature photoluminescence and photoluminescence excitation spectroscopy. The good quality of the lifted material allowed excellent excitation spectra to be observed, with both allowed and forbidden transitions being evident. The small strains induced in the chemically released layers allowed light-hole- and heavy-hole-related transitions to be easily differentiated. In addition, the layer thicknesses in the chemically released films were inferred from optical-transmission measurements and growth rates. The conduction-band offset ratio was thereby determined to be 0.57±0.05 for these quantum wells, with the light holes being borderline between type-I and type-II alignment.