基底材料对MoS2的应变场影响

The Effect of Substrate Material on Strain Field of MoS2

利用有限元法分析对生长在Au、Cu、Al2O3、SiO2、Ni这5种不同基底上的层状MoS2的应变分布进行模拟仿真.研究结果表明:基底材料的泊松比不同会使得基底和MoS2的y方向形变都不相同;基底的杨氏模量不同会使得不同基底底部与二硫化钼(MoS2)顶部的应变差别不同.在膨胀过程中,y方向底端的拉伸应变大于中间的拉伸应变,这会导致基底与顶端应变高于中间的应变.因此,基底材料的杨氏模量和泊松比与MoS2的应变分布密切相关.根据仿真结果可得,由于MoS2在Au和SiO2基底上所受到的应变较小,导致MoS2的顶端和基底底部应变差较大,因此容易造成剥离脱落;而在Al2O3基底上,由于基底材料具有较高的杨氏模量,且与MoS2比较接近,所以MoS2顶端和基底底部呈现的应变差接近.由此可见,在这些材料当中,Al2O3更适合作为MoS2的基底材料.通过研究基底材料的应变场分布,能更好地对纳米材料进行调控,从而改善器件的相关性能.

The strain distribution of layered MoS2 grown on Au,Cu,Al2O3,SiO2 and Ni was simulated by finite element method.The results show that the deformation of base and MoS2 in y direction is different due to different Poisson′s ratio of base materials.Due to different Young′s modulus of the base,the strain difference between the base bottom and the top of molybdenum disulfide is different.In the expansion process,the tensile strain at the bottom of the y direction is greater than the tensile strain at the middle,which will cause the strain at the base and the top to be higher than that at the middle.Therefore,Young′s modulus and Poisson′s ratio of base material are closely related to the strain distribution of MoS2.According to the simulation results,the strain of MoS2 on the substrate of Au and SiO2 is small.the strain difference between the top of MoS2 and the bottom of the substrate is large,so it was easy for MoS2 to be peeled off.On the substrate of Al2O3,the substrate material has a high Young′s modulus which is close to MoS2.The strain difference from the top of MoS2 is similar than the bottom of the substrate.Therefore,among these materials,Al2O3 is more suitable for MoS2 substrate material.By studying the strain field distribution of the substrate material,the nano materials can be better regulated and the related properties of the device can be improved.