Carrier injection from VO₂ into MoS₂ and WSe₂

Mahito Yamamoto^1*, 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, email:mahito.yamamoto@sanken.osaka-u.ac.jp

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