Ultra-broadband photoconductivity in twisted graphene heterostructures with large responsivity

The requirements for broadband photodetection are becoming exceedingly demanding in hyperspectral imaging. While 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 μm. Here we demonstrate a large ultra-broadband photoconductivity in twisted double bilayer graphene heterostructures spanning the spectral range of 2–100 μm with internal quantum efficiencies of approximately 40% at speeds of 100 kHz. The large 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 three-dimensional scalability.