Giant ultra-broadband photoconductivity in twisted graphene heterostructures

TL;DR

This paper reports a groundbreaking ultra-broadband photoconductivity in twisted double bilayer graphene, covering 2-100 micrometers, with high efficiency and speed, promising for hyperspectral imaging and infrared detection.

Contribution

It introduces twist-decoupled graphene heterostructures as a new, intrinsic infrared-terahertz photoconductor with broad spectral range and high efficiency, compatible with existing technologies.

Findings

Spectral range of 2-100 micrometers achieved

Internal quantum efficiency of ~40% at 100 kHz

Giant photoconductivity due to twist-induced properties

Abstract

The requirements for broadband photodetection are becoming exceedingly demanding in hyperspectral imaging. Whilst intrinsic photoconductor arrays based on mercury cadmium telluride represent the most sensitive and suitable technology, their optical spectrum imposes a narrow spectral range with a sharp absorption edge that cuts their operation to < 25 um. Here, we demonstrate a giant ultra-broadband photoconductivity in twisted double bilayer graphene heterostructures spanning a spectral range of 2 - 100 um with internal quantum efficiencies ~ 40 % at speeds of 100 kHz. The giant response originates from unique properties of twist-decoupled heterostructures including pristine, crystal field induced terahertz band gaps, parallel photoactive channels, and strong photoconductivity enhancements caused by interlayer screening of electronic interactions by respective layers acting as sub-atomic spaced proximity screening gates. Our work demonstrates a rare instance of an intrinsic infrared-terahertz photoconductor that is complementary metal-oxide-semiconductor compatible and array integratable, and introduces twist-decoupled graphene heterostructures as a viable route for engineering gapped graphene photodetectors with 3D scalability.