关键词:
controlled
synthesis
method
high-quality
MoS2
monolayer
growth
parameters
photoresponse
properties
摘要:
Two-dimensional layered materials have attracted significant interest for their potential applications in electronic and optoelectronics devices. Among them, transition metal dichalcogenides(TMDs), especially molybdenum disulfide(MoS_2), is extensively studied because of its unique properties. Monolayer MoS_2 so far can be obtained by mechanical exfoliation or chemical vapor deposition(CVD). However, controllable synthesis of large area monolayer MoS_2 with high quality needs to be improved and their growth mechanism requires more studies. Here we report a systematical study on controlled synthesis of high-quality monolayer MoS_2 single crystals using low pressure CVD. Large-size monolayer MoS_2 triangles with an edge length up to 405 μm were successfully synthesized. The Raman and photoluminescence spectroscopy studies indicate high homogenous optical characteristic of the synthesized monolayer MoS_2 triangles. The transmission electron microscopy results demonstrate that monolayer MoS_2 triangles are single crystals. The back-gated field effect transistors(FETs) fabricated using the as-grown monolayer MoS_2 show typical n-type semiconductor behaviors with carrier mobility up to 21.8 cm^2 V^(-1) s^(-1), indicating excellent electronic property comparing with previously reported CVD grown MoS_2 monolayer. The MoS_2 FETs also show a high photoresponsivity of 7 A W^(-1), as well as a fast photo-response time of 20 ms. The improved synthesis method recommended here, which makes material preparation much easier, may strongly promote further research and potential applications.