Carrier injection from VO₂ into MoS₂ and WSe₂
Mahito Yamamoto1*, Ryo Nouchi2, Teruo Kanki1, Azusa N. Hattori1, Shu Nakaharai3, Kenji Watanabe3, Takashi Taniguchi3, Yutaka Wakayama3, Keiji Ueno4
1Osaka University, Osaka, Japan
2Osaka Prefecture University, Osaka, Japan
3National Institute for Materials Science, Ibaraki, Japan
4Saitama University, Saitama, Japan
* Presenter:Mahito Yamamoto,
Transition metal oxides have much potential as “active contacts” for 2D semiconductor devices because they show a rich variety of properties such as metal-insulator transitions (MITs) and ferromagnetism. However, carrier injection properties from such “correlated oxides” into 2D semiconductors have remained elusive. Here we investigate carrier injection from VO₂, which is an archetypal correlated oxide that shows a MIT at ~340 K, into 2D MoS₂ and WSe₂ in the transistor configurations. We fabricated transistors based on MoS₂ and WSe₂ with both the drain and source electrodes being made of VO₂ microwires. We found that the VO₂-contacted MoS₂ transistor shows the n-type transport both below and above the critical temperature of the MIT. However, the barrier at the VO₂/MoS₂ contact was observed to increase by about 0.1 eV across the MIT, which is close to the previously observed work function differences between the metallic and insulating VO₂. Additionally, we observed the ambipolar transport in the transistor based on VO₂-contacted WSe₂, which has the lower electron affinity than MoS₂. These observations suggest that the carrier injection from VO₂ into the 2D semiconductors can be understood based on band theory.

Keywords: 2D semiconductors, Transition metal dichalcogenides, Transition metal oxides