Valley-Orbit Photocurrents in (111)-oriented Si-MOSFETs

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We demonstrate the injection of pure valley-orbit currents in multi-valley semiconductors and present the theory of this effect. We studied photo-induced transport in n-doped (111)-oriented silicon metal-oxide-semiconductor field effect transistors at room temperature. By shining circularly polarized light on exact oriented structures with six equivalent valleys, non-zero 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, in this work by applying linearly polarized radiation as well as by introducing a nonequivalence of the valleys by disorientation, we approve that the pure valley currents can be converted into a measurable electric current.