2D alloying molybdenum tin-disulfide monolayers with fast photoresponse.

Abstract

Elemental alloying in monolayer, two-dimensional (2D) transition metal dichalcogenides (TMDs) promises unprecedented ability to modulate their electronic structure leading to the unique optoelectronic properties. MoS2 monolayer based photodetectors typically exhibit a high photoresponsivity but suffer from a low response time. Here we develop a new approach for Sn alloying in MoS2 monolayers based on the synergy of the customized chemical vapor deposition (CVD) and the effects of common salt (NaCl) to produce high-quality and large-size Mo1-xSnxS2 (x<0.5) alloy monolayers. The composition difference results in different growth behaviors; Mo dominated alloys (x<0.5) exhibit uniform and large size (up to 100 μm) triangular monolayers, while Sn dominated alloys (x>0.5) present multilayer grains. The Mo1-xSnxS2 (x<0.5) based photodetectors and phototransistors exhibit a maximum responsitivity of 12 mA/W and a minimum response time of 20 ms, which is faster than most reported MoS2 based photodetectors. This work offers new perspectives for precision 2D alloy engineering to improve the optoelectronic performance of TMD-based photodetectors.