Chung Yun-Fang, Chang Shu-Tong
Department of Electrical Engineering, National Chung Hsing University, Taichung 402202, Taiwan.
Nanomaterials (Basel). 2024 Aug 30;14(17):1420. doi: 10.3390/nano14171420.
For semiconducting two-dimensional transition metal dichalcogenides (TMDs), the carrier transport properties of the material are affected by strain engineering. In this study, we investigate the carrier mobility of monolayer hafnium disulphide (HfS) under different biaxial strains by first-principles calculations combined with the Kubo-Greenwood mobility approach and the compact band model. The decrease/increase in the effective mass of the conduction band (CB) of monolayer HfS caused by biaxial tensile/compressive strain is the major reason for the enhancement/degradation of its electron mobility. The lower hole effective mass of the valence bands (VB) in monolayer HfS under biaxial compressive strain improves its hole transport performance compared to that under biaxial tensile strain. In summary, biaxial compressive strain causes a decrease in both the effective mass and phonon scattering rate of monolayer HfS, resulting in an increase in its carrier mobility. Under the biaxial compressive strain reaches 4%, the electron mobility enhancement ratio of the CB of monolayer HfS is ~90%. For the VB of monolayer HfS, the maximum hole mobility enhancement ratio appears to be ~13% at a biaxial compressive strain of 4%. Our results indicate that the carrier transport performance of monolayer HfS can be greatly improved by strain engineering.
对于半导体二维过渡金属二硫属化物（TMDs），材料的载流子输运特性受应变工程的影响。在本研究中，我们通过结合久保 - 格林伍德迁移率方法和紧束缚能带模型的第一性原理计算，研究了不同双轴应变下单层二硫化铪（HfS₂）的载流子迁移率。双轴拉伸/压缩应变导致单层HfS₂导带（CB）有效质量的减小/增加，是其电子迁移率增强/退化的主要原因。与双轴拉伸应变相比，双轴压缩应变下单层HfS₂价带（VB）较低的空穴有效质量改善了其空穴输运性能。总之，双轴压缩应变导致单层HfS₂的有效质量和声子散射率均降低，从而导致其载流子迁移率增加。当双轴压缩应变达到4%时，单层HfS₂导带的电子迁移率增强率约为90%。对于单层HfS₂的价带，在双轴压缩应变为4%时，最大空穴迁移率增强率似乎约为13%。我们的结果表明，通过应变工程可以极大地改善单层HfS₂的载流子输运性能。
