Absorption and photoluminescence under pressure in InGaAs/GaAs strained quantum wells

Abstract

The interband absorption of strained InGaAs/GaAs multiple quantum wells has been studied at 300 K and at 20 K for pressures up to 6 GPa. Three absorption lines have been attributed to the excitonic transitions hh1-e1, 1h1-e1 and hh2-e2. At 20 K we also measured a photoluminescence line which showed a small Stokes shift with respect to the hh1-e1 transition. The lines were visible until the Γ-X crossover pressures. At 300 K the lines disappeared around 5 GPa while at 20 K this happened around 4.5 GPa. The possible explanation could be that the Γ-X energy separation varies substantially with temperature. The pressure coefficients of the lines are the same at both temperatures and are close to the pressure coefficient of the GaAs band gap.