Biaxially stressed excitons in GaAs/AlGaAs quantum wells grown on Si substrates

Abstract

Photoluminescence and photoluminescence excitation spectroscopies are utilized to study excitons in GaAs/AlGaAs quantum wells (QW’s) fabricated by molecular beam epitaxy on a GaAs buffer layer grown on a Si substrate. The buffer layer was grown by metalorganic vapor phase epitaxy. The experimental results are understood in terms of a uniform biaxial tension of approximately 3 kbar present in the plane of growth for both the QW’s and the GaAs buffer. An important consequence of the biaxial tension is that for QW’s with well widths larger than ≊15 nm the light-hole and heavy-hole subbands cross each other in energy, resulting in a light-hole exciton energy lower than that of the heavy-hole exciton, opposite to the case of QW’s grown on GaAs substrates.