Ultrafast and Highly Stable Photodetectors Based on p-GeSe/n-ReSe₂ Heterostructures

Two-dimensional transition-metal dichalcogenide (2D-TMD) semiconductors and their van der Waals heterostructures (vdWHs) have attracted great attention because of their tailorable band-engineering properties and provide a propitious platform for next-generation extraordinary performance energy-harvesting devices. Herein, we reported unique and unreported germanium selenide/rhenium diselenide (p-GeSe/n-ReSe₂) 2D-TMD vdWH photodetectors for extremely sensitive and high-performance photodetection in the broadband spectral range (visible and near-infrared range). A high and gate-tunable rectification ratio (RR) of 7.34 × 10⁵ is achieved, stemming from the low Schottky barrier contacts and sharp interfaces of the p-GeSe/n-ReSe₂ 2D-TMD vdWHs. In addition, a noticeably high responsivity (R = 2.89 × 10⁵ A/W) and specific detectivity (D* = 4.91 × 10¹³ Jones), with good external quantum efficiency (EQE = 6.1 × 10⁵) are obtained because of intralayer and interlayer transition of excitations, enabling the broadband photoresponse (λ = 532-1550 nm) at room temperature. Furthermore, fast response times of 16-20 μs are estimated under the irradiated laser of λ = 1550 nm because of interlayer exciton transition. Such a TMD-based compact system offers an opportunity for the realization of high-performance broadband infrared photodetectors.