Broadband Linear-Dichroic Photodetector in a Black Phosphorus Vertical p-n Junction

TL;DR

This paper introduces a broadband linear-dichroic photodetector based on black phosphorus transistors that exhibits polarization sensitivity across a wide spectral range from visible to infrared, leveraging intrinsic anisotropy and electric field effects.

Contribution

The work demonstrates a novel broadband, polarization-sensitive photodetector using black phosphorus with enhanced performance due to electric field-induced charge separation.

Findings

Operates from 400 nm to 3750 nm wavelength range.

Utilizes intrinsic linear dichroism from black phosphorus anisotropy.

Electric field improves charge separation and device efficiency.

Abstract

The ability to detect light over a broad spectral range is central for practical optoelectronic applications, and has been successfully demonstrated with photodetectors of two-dimensional layered crystals such as graphene and MoS2. However, polarization sensitivity within such a photodetector remains elusive. Here we demonstrate a linear-dichroic broadband photodetector with layered black phosphorus transistors, using the strong intrinsic linear dichroism arising from the in-plane optical anisotropy with respect to the atom-buckled direction, which is polarization sensitive over a broad bandwidth from 400 nm to 3750 nm. Especially, a perpendicular build-in electric field induced by gating in black phosphorus transistors can spatially separate the photo-generated electrons and holes in the channel, effectively reducing their recombination rate, and thus enhancing the efficiency and performance for linear dichroism photodetection. This provides new functionality using anisotropic layered black phosphorus, thereby enabling novel optical and optoelectronic device applications.