Photoexcitation of valley-orbit currents in (111)-oriented silicon metal-oxide-semiconductor field-effect transistors

We demonstrate the injection of pure valley-orbit currents in multivalley semiconductors and present the phenomenological theory of this effect. We studied photoinduced transport in (111)-oriented silicon metaloxide-semiconductor field effect transistors at room temperature. By shining circularly polarized light on exact oriented structures with six equivalent valleys, nonzero electron fluxes within each valley are generated, which compensate each other and do not yield a net electric current. By disturbing the balance between the valley fluxes, we demonstrate that the pure valley-orbit currents can be converted into a measurable electric current.