Optimizing the power output of a ZnO photocell by piezopotential.

Using a metal-semiconductor-metal back-to-back Schottky contacted ZnO microwire device, we have demonstrated the piezoelectric effect on the output of a photocell. An externally applied strain produces a piezopotential in the microwire, which tunes the effective height of the Schottky barrier (SB) at the local contact, consequently changing the transport characteristics of the device. An equivalent circuit model together with the thermionic emission theory has explained the four kinds of relationships observed between the photocurrent and the applied strain. Our study shows the possibility of maximizing the output of a photocell by controlling strain in the device.