Controlling Piezoelectric Response in Semiconductor Quantum Dots via Impulsive Charge Localization

By direct observation of coherent acoustic phonons, we demonstrate a novel extrinsic piezoelectric response in colloidal CdSe semiconductor quantum dots. This response is driven by the migration of charges to the surface of the quantum dot on a vibrationally impulsive time scale. Surface- and fluence-dependent studies reveal that the observed carrier capture based piezo response is controllable and is at least an order of magnitude larger titan the intrinsic piezo response of wurtzite CdSe.