Scalable Fabrication of High-Performance Self-Powered a -MoSe 2 Thin-Film-Based Photodetectors on a-SiO 2 /Si Substrates.

Owing to its high stability, suitable absorption band gap, and fast response time, MoSe 2 has attracted the most attention in transition-metal dichalcogenides (TMDCs) for photodetector (PD) applications. In this study, based on centimeter-scale smooth amorphous MoSe 2 ( a -MoSe 2 ) thin films with thicknesses varying from 6.5 to 62.5 nm on a- SiO 2 /Si substrates prepared by polymer-assisted deposition, metal-semiconductor-metal-structured self-powered a -MoSe 2 PDs are designed and fabricated. Our data show that the PD based on 9.5 nm thick a -MoSe 2 thin film exhibits the highest values of photocurrent ( I ph , 4.60 μA), photo-to-dark current ratio (PDCR, 3067), photoresponsivity ( R λ , 0.94 mA/W), and detectivity ( D *, 4.29 × 10 10 Jones), as well as the lowest values of noise-equivalent power (NEP, 2.33 × 10 -11 W/Hz 1/2 ) and photoresponse rise/decay time (61/58 ms) under a 405 nm laser with 5 mW power at zero bias, which are better than or comparable with those of previously reported PDs based on crystalline MoSe 2 monolayers or other atomically thin 2D materials under bias voltage. The high-performance mechanism can be explained in terms of the energy band theory and volume modulation photoconductive gain model in a -MoSe 2 with a spontaneous built-in electric field. Our work provides a scalable low-cost way for the design and fabrication of high-performance self-powered TMDC PDs.