Defect control during CVD-growth for high performance MoS$lt;sub$gt;2$lt;/sub$gt;-based self-powered photodetector

Two-dimensional (2D) transition-metal dichalcogenides (TMDs) materials have unique band structure as well as excellent electrical and optical properties, which exhibit great advantages in optoelectronic devices. Chemical vapor deposition (CVD), a method to realize the synthesis of large-scale 2D TMDs materials, will inevitably introduce defects in the growth process, thus decreasing the performance of 2D TMDs-based optoelectronic devices. In order to fundamentally address this issue, we proposed a method to gradually regulate the reaction concentration of precursor during growth. As a result, the suitable concentration of precursor can effectively enhance the probability of covalent binding of X−M (X: S, Se, etc.; M: Mo, W, etc.), thus suppressing the generation of vacancy defects. Furthermore, we explored sulfur vacancy (VS) on the performance of 2D molybdenum disulfide-based (MoS2-based) self-powered devices through constructing p-type silicon/MoS2 (p-Si/MoS2) based p–n heterojunction. The photodetector composed of optimized MoS2 nanosheets exhibited high responsivity (330.14 A·W−1), fast response speed (40 μs/133 μs), and excellent photovoltage stability. This method of regulating the low temperature region during CVD growth can realize the preparation of high-quality TMDs films and be applied in high-performance optoelectronic devices.