Schottky Electric Field Induced Circular Photogalvanic Effect in Cd3As2 Nanobelts

TL;DR

This study demonstrates that Schottky electric fields can induce a circular photogalvanic effect in Cd3As2 nanobelts by breaking symmetry, enabling helicity-dependent photocurrent control at room temperature.

Contribution

It reveals a novel mechanism where Schottky electric fields induce CPGE in Dirac semimetals, expanding understanding of symmetry breaking in topological materials.

Findings

CPGE observed near metal contacts at room temperature

Schottky electric fields break symmetry, enabling CPGE

First principles calculations show topological phase transition

Abstract

Dirac semimetals are expected to forbid the manifestation of the circular photogalvanic effect (CPGE) because of their crystal inversion symmetry. Here, we report the observation of the CPGE in Cd3As2 nanobelt field effect transistors, when the photoexcitation is focused in the vicinity of the metal contacts up to room temperature. We attribute the CPGE to the Schottky electric field induced symmetry breaking, which results in the photocurrent modulation by circularly polarized photoexcitation via spin-momentum locking. The hypothesis is supported by a suite of experiments including spatially and angularly resolved helicity dependent photocurrent, Kelvin probe force microscopy, and gate voltage dependence. First principles calculations confirmed a topological phase transition upon field induced structural distortion. This work provides key insights on the electrically controlled helicity dependent optoelectronics in Dirac materials.