Nearly Ideal WS2 Diode with a Unipolar Gate Control via van der Waals Stacking Techniques

Meng-Zhan Li^1*, Jyun-Yan Siao¹, Yu-Hsun Chu¹, Minn-Tsong Lin^1,2,3

¹Department of Physics, National Taiwan University, Taipei, Taiwan
²Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
³Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan

* Presenter:Meng-Zhan Li, email:abcc102072@gmail.com

In this work, we present nearly ideal Schottky diode characteristics under electrical gating, based on multi-layer WS₂, few-layer graphene and pre-patterned Au electrodes. Our stacking approach can create asymmetric vdW contacts and an edge suspension at one-side that locally shield the gate-field, which provides decent rectification ratio (> 10⁵), near-unity ideality factor (< 1.1), and asymmetric gate-control. The gate-field effectively modulates the forward-bias current while maintaining ultralow reverse leakage currents in the picoampere range. The consistent nearly-ideal diode characteristics over the gate-sweep window are characterized by fitting the modified diode equation, and the asymmetric Schottky barrier height are obtained by temperature-dependent measurement. Furthermore, a successful implementation of edge suspension at one-side of contacts is demonstrated on a CVD-grown mono-layer WS₂ film with a PMMA supporting layer, recreating asymmetric gate-control behavior. Our results experimentally demonstrate an intriguing design that allows the applications of current rectification and gate modulation at the same time with ultrathin two-dimensional materials.
This project is financially sponsored by National Science and Technology Council (NSTC 112-2112-M-002-046-MY3)

Keywords: Ideal Schottky diode, van der Waals Stacking, Schottky barrier height