Van der Waals integration inch-scale 2D MoSe2 layers on Si for highly-sensitive broadband photodetection and imaging

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.