Develop a Field-Effect Transistor and Logic Circuits Based on a Monolayer of Tungsten Disulfide

- Published in ACS Nano, a top-tier international journal in the field of materials science (IF: 17.1, JIF ranking: 94.3%) -

 (Left) Sangjun Park, PhD Integrated Program, and Prof. Taejoon Ha

Prof. Taejoon Ha’s research team from Kwangwoon University‘s Department of Electronic Materials Engineering, in collaboration with Prof. Junyoung Kwak’s team from Ewha Womans University and Prof. Jiwon Jang’s team from Yonsei University, successfully developed a field-effect transistor with a low subthreshold swing and high voltage gain. This was achieved using a monolayer of tungsten disulfide (WS₂) grown by chemical vapor deposition as the channel layer, combined with aluminum oxide doping and a dual-gate structure based on hafnium oxide. They also successfully implemented logic circuits. The results of this study were published in ACS Nano (IF: 17.1, JIF ranking: 94.3%), a top-tier international journal in the field of materials science, under the title 'Realization of Extremely High-Gain and Low-Power in nMOS Inverter Based on Monolayer WS₂ Transistor Operating in Subthreshold Regime,' published by the American Chemical Society.

Recently, two-dimensional transition metal dichalcogenide materials, which are much thinner than conventional silicon, have been receiving significant attention as channel layers for scaling field-effect transistors. However, due to their thinness, they suffer from high gate leakage current during operation and poor gate controllability caused by charge scattering effects. In response, Prof. Taejoon Ha’s research team from the Department of Electronic Materials Engineering, in collaboration with Prof. Junyoung Kwak’s team from Ewha Womans University and Prof. Jiwon Jang’s team from Yonsei University, developed a WS₂ field-effect transistor with a low subthreshold swing and high voltage gain using aluminum oxide doping and a dual-gate structure based on hafnium oxide. They successfully implemented an inverter using this approach. The fabricated WS₂ field-effect transistor exhibited a high on/off ratio of approximately 10¹？ and a low subthreshold swing of 88 mV/dec. Additionally, based on this, they successfully implemented an NMOS inverter logic circuit with a high voltage gain of up to 2056 and extremely low power consumption of approximately 2.3 pWm-1.

Meanwhile, this research was conducted as part of the University Innovation Future Challenge Project, with collaborative efforts from the Interactive Display Research Center, led by Prof. Taejoon Ha as the director. It was also supported by the university’s internal academic research funding program at Kwangwoon University. Prof. Taejoon Ha's research team is conducting extensive research not only on the design of next-generation electronic devices based on advanced materials but also on process development. Their work, focused on next-generation semiconductors such as carbon nanotubes, graphene, and two-dimensional transition metal dichalcogenides, has resulted in the publication of over 60 SCI journal articles and the filing of more than 30 international and domestic patents.

WS₂ Field-Effect Transistors Doped with Aluminum Oxide and Analysis of Their Application in Inverters