Efforts toward Forming Ohmic Contact to Monolayer Molybdenum Disulfide
Albert Yen-Po Liu1*, Yu-Ting Lin1, Yen-Hao Huang1, Chia-Wei Chou1, Kuan-Chang Chiu2, Chang-Ning Liao2, Meng-Hsi Chuang2, Yi-Hsien Lee2, Yung-Fu Chen1
1Department of Physics, National Central University, Jhongli, Taiwan
2Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan
* presenting author:彥伯劉, email:ybliu8129@gmail.com
Monolayer molybdenum disulfide (MoS2) is a two-dimensional semiconductor with direct band gap of 1.8 eV. Due to its unique electronic and optoelectronic properties, MoS2-based thin-film devices are fabricated to study novel physical properties in MoS2, such as quantum Hall effect and spin-valley coupling. However, the existence of large metal-MoS2 Schottky barrier results in insulating behaviors at low bias regimes and hinder further electronic studies in MoS2. In this work, we use several metals, such as Ti, Au and Pd, as wetting layer and demonstrate improved metal-MoS2 contacts. In addition, O2 and H2O absorbents are believed to deplete negative charge carriers in MoS2. We find annealing via heating in vacuum environment or injecting large current through metal-MoS2 contacts further improves the contacts owing to absorbent detachment.

Keywords: molybdenum disulfide, Monolayer, Schottky barrier, contact resistance