Orbital photogalvanic effects in quantum-confined structures

TL;DR

This paper investigates the orbital origin of photogalvanic effects in silicon quantum structures, demonstrating how polarization, wavelength, and temperature influence photocurrents, supported by experimental data and theoretical models.

Contribution

It provides a detailed microscopic and phenomenological theory explaining the orbital nature of circular photogalvanic effects in silicon-based quantum-confined structures.

Findings

Circular photocurrent is of pure orbital origin.

Photocurrent depends on polarization, wavelength, and temperature.

Theoretical models align with experimental observations.

Abstract

We report on the circular and linear photogalvanic effects caused by free-carrier absorption of terahertz radiation in electron channels on (001)-oriented and miscut silicon surfaces. The photocurrent behavior upon variation of the radiation polarization state, wavelength, gate voltage and temperature is studied. We present the microscopical and phenomenological theory of the photogalvanic effects, which describes well the experimental results. In particular, it is demonstrated that the circular (photon-helicity sensitive) photocurrent in silicon-based structures is of pure orbital nature originating from the quantum interference of different pathways contributing to the absorption of monochromatic radiation.