Being capable of sensing broadband infrared (IR) light is vitally important for wide-ranging applications from fundamental science to industrial purposes. Two-dimensional (2D) topological semimetals are being extensively explored for broadband IR detection due to their gapless electronic structure and the linear energy dispersion relation. However, the low charge separation efficiency, high noise level, and on-chip integration difficulty of these semimetals significantly hinder their further technological applications. Here, we demonstrate a facile thermal-assisted tellurization route for the van der Waals (vdW) growth of wafer-scale phase-controlled 2D MoTe₂ layers. Importantly, the type-II Weyl semimetal 1T′-MoTe₂ features a unique orthorhombic lattice structure with a broken inversion symmetry, which ensures efficient carrier transportation and thus reduces the carrier recombination. This characteristic is a key merit for the well-designed 1T′-MoTe₂/Si vertical Schottky junction photodetector to achieve excellent performance with an ultrabroadband detection range of up to 10.6 µm and a large room temperature specific detectivity of over 10⁸ Jones in the mid-infrared (MIR) range. Moreover, the large-area synthesis of 2D MoTe₂ layers enables the demonstration of high-resolution uncooled MIR imaging capability by using an integrated device array. This work provides a new approach to assembling uncooled IR photodetectors based on 2D materials.

There is an emerging need for high-sensitivity solar-blind deep ultraviolet (DUV) photodetectors with an ultra-fast response speed. Although nanoscale devices based on Ga₂O₃ nanostructures have been developed, their practical applications are greatly limited by their slow response speed as well as low specific detectivity. Here, the successful fabrication of two-/three-dimensional (2D/3D) graphene (Gr)/PtSe₂/β-Ga₂O₃ Schottky junction devices for high-sensitivity solar-blind DUV photodetectors is demonstrated. Benefitting from the high-quality 2D/3D Schottky junction, the vertically stacked structure, and the superior-quality transparent graphene electrode for effective carrier collection, the photodetector is highly sensitive to DUV light illumination and achieves a high responsivity of 76.2 mA/W, a large on/off current ratio of ∼ 10⁵, along with an ultra-high ultraviolet (UV)/visible rejection ratio of 1.8 × 10⁴. More importantly, it has an ultra-fast response time of 12 µs and a remarkable specific detectivity of ∼ 10¹³ Jones. Finally, an excellent DUV imaging capability has been identified based on the Gr/PtSe₂/β-Ga₂O₃ Schottky junction photodetector, demonstrating its great potential application in DUV imaging systems.

A self-driven and broadband photodetector based on PdSe₂/SiNWA mixed-dimensional vdW heterojunction is fabricated, which shows a broadband spectrum from 200 nm to 4.6 μm with a high polarization sensitivity and good mid-infrared imaging capability.