Abstract
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.
Highlights
Grain boundary is one kind of defect which usually decreases the electrical and thermal conductivity of the materials
In contrast with the variable-range hopping (VRH) transport at low temperature, Bthe nearest-neighbor hopping (NNH) model at high temperature is reasonable for impeding the electrical transport by twin grain boundary (GB) which serves as the line defects, scattering centers for charge carriers that can decrease the conductivity
In contrast with the VRH transport at low temperature, the NNH model at high temperature is reasonable for impeding the electrical transport by twin GB which serves as the line defects, scattering centers for charge carriers that can decrease the conductivity
Summary
Grain boundary is one kind of defect which usually decreases the electrical and thermal conductivity of the materials. Crystals 2016, 6, 115 twin GB holds a crucial role in tailoring the properties of a semiconducting MoS2 monolayer, the typical layered transition metal dichalcogenides (TMDCs), which shows novel properties, such as valley polarization [4,5,6], valley hall effect [7,8], superconductivity [9,10,11], high on/off ratio [12], metal-insulator transition [12,13], unconventional quantum Hall effect, and a tunable spin Hall effect [14]. Different from the tilt GB of MoS2 that causes strong photoluminescence enhancement and decreases the electrical conductivity [15], it has been reported that one-dimensional mid-gap. The twin GB causes strong photoluminescence increases the electrical conductivity at room crucial role in tailoring the quenching properties of and a semiconducting. 2 is essential.enhancement the electrical conductivity has beentransport reported that one-dimensional mid-gap the twin GBdecreases device and directly examine[15], theitcarrier properties of the twin metallic. Twin GB Synthesis and the Atomistic Model us to elucidate the roles of twin GB of MoS2 in the electrical transport
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