Pressure studies in InGaN/GaN quantum wells

In this work we investigate the effect of hydrostatic pressure on the optical properties of InGaN/GaN quantum wells with wurtzite lattice configuration. The photoluminescence from such wells shows anomalously small pressure coefficient, much smaller than that of the bulk materials forming the wells. Our systematic study of quantum wells with different width and with different barrier doping points to the increasing piezoelectric field with pressure across the wells as the mechanism uniquely responsible for such behavior. The increase of the piezoelectric field across the wells is a consequence of nonlinear piezoelectric effect, i.e. variation of the piezoelectric constants of InGaN and GaN with strain.