Photoluminescence of (111) ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}/\mathrm{GaAs}$ strained-layer quantum wells under hydrostatic pressure

The unexpectedly low values of the hydrostatic pressure coefficients of the band gaps of compressively strained (001) quantum wells are due to nonlinear elasticity effects in the interaction of external pressure and internal coherency strain. In (111)-oriented quantum wells compressive strain lowers the pressure coefficient, in contradiction to our previous report, but in agreement with recent work and in accordance with nonlinear elasticity theory. We compare recent experimental results with the predictions of the theory of the nonlinear elastic effects in strained layers.