Oxidized-monolayer tunneling barrier for strong Fermi-level depinning in layered InSe transistors

Yi Hsun Chen, Chih Yi Cheng, Shao Yu Chen, Jan Sebastian Dominic Rodriguez, Han Ting Liao, Kenji Watanabe, Takashi Taniguchi, Chun Wei Chen, Raman Sankar, Fang Cheng Chou, Hsiang Chih Chiu, Wei Hua Wang

Research output: Contribution to journalArticleResearchpeer-review

18 Citations (Scopus)


In two-dimensional (2D)-semiconductor-based field-effect transistors and optoelectronic devices, metal–semiconductor junctions are one of the crucial factors determining device performance. The Fermi-level (FL) pinning effect, which commonly caused by interfacial gap states, severely limits the tunability of junction characteristics, including barrier height and contact resistance. A tunneling contact scheme has been suggested to address the FL pinning issue in metal–2D-semiconductor junctions, whereas the experimental realization is still elusive. Here, we show that an oxidized-monolayer-enabled tunneling barrier can realize a pronounced FL depinning in indium selenide (InSe) transistors, exhibiting a large pinning factor of 0.5 and a highly modulated Schottky barrier height. The FL depinning can be attributed to the suppression of metal- and disorder-induced gap states as a result of the high-quality tunneling contacts. Structural characterizations indicate uniform and atomically thin-surface oxidation layer inherent from nature of van der Waals materials and atomically sharp oxide–2D-semiconductor interfaces. Moreover, by effectively lowering the Schottky barrier height, we achieve an electron mobility of 2160 cm2/Vs and a contact barrier of 65 meV in two-terminal InSe transistors. The realization of strong FL depinning in high-mobility InSe transistors with the oxidized-monolayer presents a viable strategy to exploit layered semiconductors in contact engineering for advanced electronics and optoelectronics.

Original languageEnglish
Article number49
Number of pages7
Journalnpj 2D Materials and Applications
Issue number1
Publication statusPublished - 13 Dec 2019

Cite this