Clean BN-Encapsulated 2D FETs with Lithography-Compatible Contacts

Binxi Liang; Anjian Wang; Jian Zhou; Shihao Ju; Jian Chen; Kenji Watanabe; Takashi Taniguchi; Yi Shi; Songlin Li

doi:10.1021/acsami.2c02956

Clean BN-Encapsulated 2D FETs with Lithography-Compatible Contacts

ACS Appl Mater Interfaces. 2022 Apr 27;14(16):18697-18703. doi: 10.1021/acsami.2c02956. Epub 2022 Apr 18.

Authors

Binxi Liang^{1

2}, Anjian Wang^{1

2}, Jian Zhou^{1

2}, Shihao Ju^{1

2}, Jian Chen^{1

2}, Kenji Watanabe³, Takashi Taniguchi³, Yi Shi^{1

2}, Songlin Li^{1

2}

Affiliations

¹ National Laboratory of Solid-State Microstructures and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, Jiangsu 210023, China.
² School of Electronic Science and Engineering, Nanjing University, Nanjing, Jiangsu 210023, China.
³ National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan.

PMID: 35436083
DOI: 10.1021/acsami.2c02956

Abstract

Device passivation through ultraclean hexagonal BN encapsulation has proven to be one of the most effective ways of constructing high-quality devices with atomically thin semiconductors that preserve the ultraclean interface quality and intrinsic charge transport behavior. However, it remains challenging to integrate lithography-compatible contact electrodes with flexible distributions and patterns. Here, we report the feasibility of a straightforward integration of lithography-defined contacts into BN-encapsulated two-dimensional field-effect transistors (2D FETs), giving rise to overall device quality comparable to the state-of-the-art results from the painstaking pure dry transfer processing. The electronic characterization of FETs consisting of WSe₂ and MoS₂ channels reveals an extremely low scanning hysteresis of ∼2 mV on average, a low density of interfacial charged impurities of ∼10¹¹ cm^-2, and generally high charge mobilities over 1000 cm² V^-1 s^-1 at low temperatures. The overall high device qualities verify the viability of directly integrating lithography-defined contacts into BN-encapsulated devices to exploit their intrinsic charge transport properties for advanced electronics.

Keywords: 2D semiconductors; boron nitride; charge mobility; electronic transport; field-effect transistors; nanoelectronics; scattering mechanism; transition-metal chalcogenides.