Charge-Separation Kinetics of Photoexcited Oxygen Vacancies in ZnO Nanowire Field-Effect Transistors

Shining light on a semiconductor can create electron-hole pairs---the well known basis of all photovoltaic cells. However, the processes behind photogeneration and recombination of pairs remain unclear at the nanoscale, where Coulombic attraction becomes quite strong. The authors use FET structures to control the surface electric field and study charge separation in photoexcited ZnO nanowires Their results aid our understanding of the physics behind the responses of phototransistors and photosensors, the quantum efficiencies of solar cells, and the reactivities of photocatalytic and photochemical systems at the nanoscale.