Band offset in elastically strained InGaAs/GaAs multiple quantum wells determined by optical absorption and electronic Raman scattering

Abstract

Pseudomorphic InGaAs/GaAs multiple quantum well structures with In contents ranging from 18 to 25% were grown by molecular beam epitaxy and investigated by optical absorption, photoluminescence, and electronic Raman scattering. Sharp exciton peaks with linewidths of ∼3 meV for the first electron to heavy hole transition are observed in the absorption spectra. The electron subband structure was investigated independently by electronic Raman scattering. The transition energies are analyzed using a four-band effective mass Schrödinger equation taking strain into account. A conduction-band offset ratio ΔEc/ΔEg=0.6 is found for all samples independent of In content.