Significant strain dependence of piezoelectric constants inInxGa1−xN/GaNquantum wells

Using hydrostatic pressure to modify the strain in ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{N}/\mathrm{G}\mathrm{a}\mathrm{N}$ quantum wells we show an almost twofold increase of the built-in piezoelectric field in the wells from 1.4 MV/cm at atmospheric pressure to 2.6 MV/cm at 8.7 GPa. An analysis in terms of the total strain generated by the pressure suggests that the increase in the field arises from a significant dependence of the piezoelectric constants on strain.