Structural or crystal asymmetry are necessary conditions for emergence of zero-bias photocurrent in light detectors. Structural asymmetry has been typically achieved via p−n doping being a technologically complex process. Here, we propose an alternative approach to achieve zero-bias photocurrent in 2d material flakes exploiting the geometrical non-equivalence of source and drain contacts. As a prototypical example, we equip a square-shaped flake of PdSe2 with mutually orthogonal metal leads. Upon uniform illumination with linearly-polarized light, the device demonstrates non-zero photocurrent which flips its sign upon 90∘ polarization rotation. The origin of zero-bias photocurrent lies in polarization-dependent lightning-rod effect. It enhances the electromagnetic field at one contact from the orthogonal pair, and selectively activates the internal photoeffect at the respective metal-PdSe2 Schottky junction. The proposed technology of contact engineering can be extended to arbitrary 2d materials and detection of both polarized and natural light.
@article{arxiv.2303.16782,
title = {Zero-bias photodetection in 2d materials via geometric design of contacts},
author = {Valentin A. Semkin and Aleksandr V. Shabanov and Dmitry A. Mylnikov and Mikhail A. Kashchenko and Ivan K. Domaratskiy and Sergey S. Zhukov and Dmitry A. Svintsov},
journal= {arXiv preprint arXiv:2303.16782},
year = {2023}
}