Inversion of the exciton built-in dipole moment in In(Ga)As quantum dots via nonlinear piezoelectric effect

Piezoelectric effects can strongly affect the position and shape of the electron and hole wave functions in compound semiconductors quantum dots (QDs). From the point of view of theoretical semiconductor physics, this is a well-documented notion. From an experimental point of view, however, the extreme sensitivity of the electronic properties of QDs to tiny variations of their shape, size, and composition makes it very challenging to single out the effect of piezoelectricity, which is often neglected in the analysis of experimental data. Here, the authors demonstrate that externally induced piezoelectric fields can be used for wave function engineering and to even force an inversion of the exciton built-in dipole moment in the very same QD. Detailed calculations based on k.p theory disclose that the inversion of the exciton dipole is driven by the nonlinear terms of the piezoelectric fields. These findings shine new light on the role and the possible exploitation of piezoelectric effects in semiconductor QDs.