Piezoelectric polarization of semipolar and polar GaInN quantum wells grown on strained GaN templates

Piezoelectric polarization in GaInN/GaN quantum well (QW) structures is not only dependent on the strain in the pseudomorphically grown QWs but also severely influenced by the strain already present in the underlying template. Here, we investigate the influence of template strain on the piezoelectric polarization of QWs grown in the polar [0001] and in semipolar off-[0001] directions. We find that an efficient strain-engineering can be used to decrease polarization fields or even cancel them out completely. Even a change of sign of the built-in polarization fields within QWs can be achieved in certain strain-situations. Our results shed light on recent ambiguous results concerning the piezoelectric tensor component e15 and are able to explain unexpected differences in device performance of polar and semipolar QW devices.