Piezoresistivity and Strain-induced Band Gap Tuning in Atomically Thin MoS2
Piezoresistivity and Strain-induced Band Gap Tuning in Atomically Thin MoS2
复制标题
DOI：
10.1021/acs.nanolett.5b01689
复制
发表时间：
2015-08-01
期刊：
影响因子：
10.8
通讯作者：
Kis, Andras
中科院分区：
文献类型：
--
作者：
Manzeli, Sajedeh;Allain, Adrien;Kis, Andras
材料性能的连续调节在广泛的应用中是非常理想的，应变工程是实现这一点的一种有趣的方式。然而，由于存在缺陷和位错，传统的块体材料可能会受到塑性和低断裂极限的影响，因此调节范围有限。另一方面，诸如MoS 2的原子薄膜表现出高的杨氏模量和断裂强度，这使得它们成为通过应变改变其性质的可行候选者。MoS 2的带隙是高度应变可调的，这导致其电导率的调制，并表现为压阻效应，而压电效应也观察到在奇数层的MoS 2与破缺的反转对称。这种电性能和机械性能之间的耦合使得MoS 2成为纳米机电系统（NEMS）非常有前途的材料。在这里，我们将单层，双层和三层二硫化钼在纳米机电膜配置。我们通过电导率测量检测应变诱导的带隙调谐，并证明了在二硫化钼的压阻效应的出现。有限元法（FEM）模拟被用来量化的带隙变化，并获得一个全面的图片上的膜的空间变化的带隙分布。对于单层、双层和三层MoS 2，压阻应变计因子分别计算为-148 +/-19、-224 +/-19和-43.5 +/-11，这与现有技术的硅应变传感器相当，并且比基于悬浮石墨烯的应变传感器高2个数量级。使用应变诱导带隙调谐的2D纳米材料中电阻率的可控调制为实现一类重要的NEMS换能器、柔性和可穿戴电子器件、可调谐光电器件和光电探测提供了一种新方法。
Continuous tuning of material properties is highly desirable for a wide range of applications, with strain engineering being an interesting way of achieving it. The tuning range, however, is limited in conventional bulk materials that can suffer from plasticity and low fracture limit due to the presence of defects and dislocations. Atomically thin membranes such as MoS2 on the other hand exhibit high Young's modulus and fracture strength, which makes them viable candidates for modifying their properties via strain. The bandgap of MoS2 is highly strain-tunable, which results in the modulation of its electrical conductivity and manifests itself as the piezoresistive effect, whereas a piezoelectric effect was also observed in odd-layered MoS2 with broken inversion symmetry. This coupling between electrical and mechanical properties makes MoS2 a very promising material for nanoelectromechanical systems (NEMS). Here, we incorporate monolayer, bilayer, and trilayer MoS2 in a nanoelectromechanical membrane configuration. We detect strain-induced band gap tuning via electrical conductivity measurements and demonstrate the emergence of the piezoresistive effect in MoS2. Finite element method (FEM) simulations are used to quantify the band gap change and to obtain a comprehensive picture of the spatially varying bandgap profile on the membrane. The piezoresistive gauge factor is calculated to be -148 +/- 19, -224 +/- 19, and -43.5 +/- 11 for monolayer, bilayer, and trilayer MoS2, respectively, which is comparable to state-of-the-art silicon strain sensors and 2 orders of magnitude higher than in strain sensors based on suspended graphene. Controllable modulation of resistivity in 2D nanomaterials using strain-induced bandgap tuning offers a novel approach for implementing an important class of NEMS transducers, flexible and wearable electronics, tunable photovoltaics, and photodetection.