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

TL;DR

This paper demonstrates the generation and control of pure valley-orbit currents in (111)-oriented silicon MOSFETs using polarized light, revealing how valley flux imbalance leads to measurable electric currents.

Contribution

It introduces a method to generate and manipulate pure valley currents in silicon MOSFETs through optical excitation and structural disorientation, supported by theoretical analysis.

Findings

Pure valley currents can be generated with circularly polarized light.

Imbalance of valley fluxes results in measurable electric currents.

Valley currents are controllable via polarization and structural orientation.

Abstract

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.