The effect of twin grain boundary tuned by temperature on the electrical transport properties of monolayer MoS₂

Theoretical calculation and experimental measurement have shown that twin grain boundary (GB) of molybdenum disulphide (MoS₂) exhibits extraordinary effects on transport properties. Precise transport measurements need to verify the transport mechanism of twin GB in MoS₂. Here, monolayer molybdenum disulphide with a twin grain boundary was grown in our developed low-pressure chemical vapor deposition (CVD) system, and we investigated how the twin GB affects the electrical transport properties of MoS₂ by temperature-dependent transport studies. At low temperature, the twin GB can increase the in-plane electrical conductivity of MoS₂ and the transport exhibits variable-range hopping (VRH), while at high temperature, the twin GB impedes the electrical transport of MoS₂ and the transport exhibits nearest-neighbor hopping (NNH). Our results elucidate carrier transport mechanism of twin GB and give an important indication of twin GB in tailoring the electronic properties of MoS₂ for its applications in next-generation electronics and optoelectronic devices.