Analyzing the Potential Barrier via Charge Transfer and the Resulting Transmission Coefficient in 2D Monolayer TMD Nanojunctions

Ken-Ming Lin^1*, Yi-Chen Lin², Tzu-Pei Yang¹, Po-Yu Lin¹, Yu-Chang Chen^1,3

¹Department of Electrophyscis, National Yang Ming Chiao Tung University, Hsinchu city, Taiwan
²Department of Physics, National Taiwan Univeristy, Taipei city, Taiwan
³Center for Theoretical and Computational Physics, National Yang Ming Chiao Tung University, Hsinchu city, Taiwan

* Presenter:Ken-Ming Lin, email:ken.ming.lin@gmail.com

Nanoscale junctions may support both quantum tunneling and semi-classical currents. The competition between them in a two-dimensional field effect transistor with a metal dichalcogenides mono-layer (TMD) channel remains unexplored. To better understand the transition from semiclassical transport to quantum tunneling regimes, we developed a method for calculating the potential profile and currents. The potential, including Schottky barriers, is calculated using the Poisson equation, with charge transfer between aluminum electrodes and WSe2 monolayer as the channel material. The currents are calculated using the Landauer formula in conjunction with transmission functions obtained from the potential using 3D NEGF. Our method can differentiate between contributions from semi-classical thermionic and quantum tunneling currents. The quantum transport regime is expanded by lowering the temperature, decreasing the channel length, increasing the source-drain bias, and adjusting the chemical potential away from the Schottky barrier height through gate voltage manipulation. The classic current is independent of the channel length when the channel length is shorter than that of mean-free path. However, it would be length dependent for a long channel. Our results suggest a possible underlying mechanism that can simultaneously improve source–drain current conduction and mitigate leakage current in nanoscale monolayer TMD field-effect transistors.

Keywords: electronic transport in semiconductors, quantum transport, NEGF, monolayer transition metal dichalcogenides