MX2型二维半导体载流子迁移率理论预测

The upper limit of electron and hole mobilities in two dimensional MX_2 semiconductors

为找到未来半导体晶体管合适的沟道材料,计算了14种MX_2(其中M=Mo,W,Sn,Hf,Zr和Pt,X=S,Se和Te)型二维半导体载流子有效质量、带隙以及电子和空穴迁移率。在计算过程中,为了快速对载流子迁移率进行估计,利用形变势的近似电声耦合矩阵元。计算时考虑长波光学声子和声学声子的散射,而在极化晶体中,考虑了极化散射。计算结果表面,WS_2,PtS_2以及PtSe_2具有最高的电子迁移率以及非零的带隙。其中,PtSe_2的电子在室温下的理论迁移率上限为4000 cm^2·V^(-1)·s^(-1),而W,Hf和Zr的二维化合物室温时的空穴迁移率较高,其中含W的化合物理论迁移率上限到2600 cm^2·V^(-1)·s^(-1)。该计算研究为实验合成高迁移率的二维材料提供指导,同时为实验获得高性能以二维材料作为沟道的场效应晶体管提供参考,加速二维材料的应用。

We calculated the electron and hole mobility of 14 two dimensional semiconductors with composition of MX 2,where M(=Mo,W,Sn,Hf,Zr and Pt)is the transition metal,and X is S,Se and Te.We treated the scattering matrix by the deformation potential approximation.Long wave longitudinal acoustical and optical phonon scatterings are included.Piezoelectric scattering in the compounds without inversion symmetry is also taken into account.We found that out of the 14 compounds,WS 2,PtS 2 and PtSe 2,are promising regarding to the possible high electron mobility and finite band gap.The phonon limited mobility in PtSe 2 reaches about 4000 cm^2·V^-1·s^-1 at room temperature which is the highest among the compounds.While WX 2,HfX 2 and ZrX 2,due to the possible high hole mobility and finite band gap,are also promising.The phonon limited mobilities in WX 2 reach about 2600 cm 2·V^-1·s^-1 at room temperature,which is much larger than their electron mobility.Our results can be a guide for experiments to search for better two-dimensional materials for future semiconductor devices.