Effect of hydrostatic pressure on GaAs-Ga1−xAlxAs microstructures

Some detailed experimental studies of the effect of hydrostatic pressure on the energy levels of GaAs-${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Al}}_{\mathrm{x}}$As quantum-well heterostructures have been recently published. The heterostructures used are grown by molecular-beam epitaxy and consist of several single GaAs wells with different widths separated by wide ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Al}}_{\mathrm{x}}$As barriers. Photoluminescence measurements at low temperature and up to 70 kbar show that all the peaks move to higher energy as the pressure is applied. The pressure coefficients of the heavy- and light-hole excitonic transitions appear to be different. On the other hand these coefficients decrease with decreasing well widths. In this paper we present a theoretical calculation of these pressure coefficients and of their well-width and barrier-height dependence, which quantitatively fits the experimental results.