Investigation on the piezoelectrical properties of single layered MoS2 at various temperatures

Single layered MoS2 has been actively studied as a next-generation material to replace Si. Because Single layered MoS2 is a semiconductor unlike graphene and it has the tunable bandgap as decreasing its thickness. Besides,... [ view full abstract ]

Single layered MoS₂ has been actively studied as a next-generation material to replace Si. Because Single layered MoS₂ is a semiconductor unlike graphene and it has the tunable bandgap as decreasing its thickness. Besides, single layered MoS₂ has a charge mobility of 217 cm²/V•S comparable to Si thin film or graphene nanoribbons and its on / off ratio is around 10⁸ with abrupt electrical switching.[1] Also, several researchers reported that single layered MoS₂ had unchanging electrical properties during or after mechanical bending. These papers make MoS₂ a candidate material of the flexible device. However, Wu et al. observed that when odd layered MoS2 was under the strain, its transport behavior showed a strong piezoelectrical characteristics due to strain-induced lattice distortion and the associated ion charge polarization.[2] Also, Jena et al. reported calculated results of the piezoelectric stress and the strain coefficient change under the strain.[3] Therefore, the transport behavior change of single layred MoS₂ during strain is still under debate. In this study, we investigated the electrical properties of single layered MoS₂ grown by CVD method while varying strains. First of all, we checked the temperature dependent resistance change of our MoS₂. As previous other groups reported, we was confirmed that our single layered MoS₂ also followed the variable-range hopping model. After transferring MoS₂ to the flexible substrate, we measured Schottky barrier height of the MoS₂ while varying the strain. Also, we investigated the piezoelectrical property of MoS₂ while sample temperature changed from 270 K to room temperature.