An in-plane photoelectric effect in two-dimensional electron systems for terahertz detection

TL;DR

This paper reports the discovery of an in-plane photoelectric effect in two-dimensional electron systems, enabling highly efficient terahertz detection with a giant zero-bias photoresponse surpassing existing mechanisms.

Contribution

It introduces a novel in-plane photoelectric effect in 2D electron gases, demonstrating a new quantum-mechanical, scattering-free process for terahertz photodetection.

Findings

Giant zero-bias photoresponse exceeds known mechanisms by over 10 times

In-plane photoelectric effect occurs within a 2D electron gas

Tunable in-situ work function enhances device performance

Abstract

The photoelectric effect consists in the photoexcitation of electrons above a potential barrier at a material interface and is exploited for photodetection over a wide frequency range. This three-dimensional process has an inherent inefficiency: photoexcited electrons gain momenta predominantly parallel to the interface, while to leave the material they have to move perpendicular to it. Here, we report on the discovery of an in-plane photoelectric effect occurring within a two-dimensional electron gas. In this purely quantum-mechanical, scattering-free process, photo-electron momenta are perfectly aligned with the desired direction of motion. The "work function" is artificially created and tunable in-situ. The phenomenon is utilized to build a direct terahertz detector, which yields a giant zero-bias photoresponse that exceeds the predictions by known mechanisms by more than 10-fold. This new aspect of light-matter interaction in two-dimensional systems paves the way towards a new class of highly efficient photodetectors covering the entire terahertz range.