Investigation On Controllable Growth And Electronic Transport Properties Of Two-dimensional MoS₂

As a member of semiconducting transition metal dichalcogenides,monolayer MoS2 exhibits good crystallinity,flexibility and stability.Semiconducting MoS2 is one of the most important 2D materials with natural bandgap and has further applications in microelectronics and optoelectronic devices.In this paper,monolayer,bilayer and multilayer MoS2 and monolayer MoS2 with different morphologies were grown by atmospheric chemical vapor deposition(CVD).The growth rhythm of MoS2 was summarized.In addition,a bottom-gate field effect transistor(MOSFET)with monolayer MoS2 channel was fabricated,and its electrical and photoelectric characteristic were characterized.The details are shown as follows:(1)The growth of two-dimensional MoS2 was controlled and optimized,and the growth parameters were studied.The results showed that the seed promoter can greatly promote the lamellar growth of MoS2.The amount of loaded S/Mo source and growth time could affect the number of layers of MoS2.The flow rate of carrier gas had a remarkable effect on the structural stability of MoS2.Early timing of S source could effectively reduce the formation of rhombohedral MoO2.(2)Further study of growth temperature and growth condition(mass ratio of S/Mo source)has been carried out to figure out the growth mechanism of monolayer MoS2 with different morphological and dimensions.The results showed that the increase of temperature promoted the size of MoS2.Different growth conditions affected the growth pattern of MoS2.MoS2 tend to grow to be triangles in S-rich and S-deficient conditions,and tend to be hexagonal in a balanced condition.(3)A bottom-gate field effect transistor(MOSFET)with monolayer MoS2 channel was fabricated.The transfer curves showed that the mobility of monolayer MoS2 was approximately 0.8 cm2V-1s-1,and the on/off ratio was around 103-104.When the device was exposed to 580 nm yellow light,under the negative gate voltage,the current was increased by one order of magnitude compared with the dark condition,indicating that monolayer MoS2 has strong light response characteristics...