High-sensitivity room-temperature multi-dimensional infrared (IR) detection is crucial for military and civilian purposes. Recently, the gapless electronic structures and unique optoelectrical properties have made the two-dimensional (2D) topological semimetals promising candidates for the realization of multifunctional optoelectronic devices. Here, we demonstrated the in-situ construction of high-performance 1T’-MoTe₂/Ge Schottky junction device by inserting an ultrathin AlO_x passivation layer. The good detection performance with an ultra-broadband detection wavelength range of up to 10.6 micron, an ultrafast response time of ~ 160 ns, and a large specific detectivity of over 10⁹ Jones in mid-infrared (MIR) range surpasses that of most 2D materials-based IR sensors, approaching the performance of commercial IR photodiodes. The on-chip integrated device arrays with 64 functional detectors feature high-resolution imaging capability at room temperature. All these outstanding detection features have enabled the demonstration of position-sensitive detection applications. It demonstrates an exceptional position sensitivity of 14.9 mV/mm, an outstanding nonlinearity of 6.44%, and commendable trajectory tracking and optoelectronic demodulation capabilities. This study not only offers a promising route towards room-temperature MIR optoelectronic applications, but also demonstrates a great potential for application in optical sensing systems.

As one of the most promising materials for two-dimensional transition metal chalcogenides (2D TMDs), molybdenum diselenide (MoSe₂) has great potential in photodetectors due to its excellent properties like tunable bandgap, high carrier mobility, and excellent air stability. Although 2D MoSe₂-based photodetectors have been reported to exhibit admired performance, the large-area 2D MoSe₂ layers are difficult to be achieved via conventional synthesis methods, which severely impedes its future applications. Here, we present the controllable growth of large-area 2D MoSe₂ layers over 3.5-inch with excellent homogeneity by a simple post-selenization route. Further, a high-quality n-MoSe₂/p-Si van der Waals (vdW) heterojunction device is in-situ fabricated by directly growing 2D n-MoSe₂ layers on the patterned p-Si substrate, which shows a self-driven broadband photoresponse ranging from ultraviolet to mid-wave infrared with an impressive responsivity of 720.5 mA·W⁻¹, a high specific detectivity of 10¹³ Jones, and a fast response time to follow nanosecond pulsed optical signal. In addition, thanks to the inch-level 2D MoSe₂ layers, a 4 × 4 integrated heterojunction device array is achieved, which has demonstrated good uniformity and satisfying imaging capability. The large-area 2D MoSe₂ layer and its heterojunction device array have great promise for high-performance photodetection and imaging applications in integrated optoelectronic systems.

Two-dimensional (2D) layered materials have been considered promising candidates for next-generation optoelectronics. However, the performance of 2D photodetectors still has much room for improvement due to weak light absorption of planar 2D materials and lack of high-quality heterojunction preparation technology. Notably, 2D materials integrating with mature bulk semiconductors are a promising pathway to overcome this limitation and promote the practical application on optoelectronics. In this work, we present the patterned assembly of MoSe₂/pyramid Si mixed-dimensional van der Waals (vdW) heterojunction arrays for broadband photodetection and imaging. Benefited from the light trapping effect induced enhanced optical absorption and high-quality vdW heterojunction, the photodetector demonstrates a wide spectral response range from 265 to 1550 nm, large responsivity up to 0.67 A·W⁻¹, high specific detectivity of 1.84 × 10¹³ Jones, and ultrafast response time of 0.34/5.6 μs at 0 V. Moreover, the photodetector array exhibits outstanding broadband image sensing capability. This study offers a novel development route for high-performance and broadband photodetector array by MoSe₂/pyramid Si mixed-dimensional heterojunction.

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.