Open AccessTip-Based Cleaning and Smoothing Improves Performance in Monolayer MoS2 Devices
Author(s) -
Sihan Chen,
Jangyup Son,
Siyuan Huang,
Kenji Watanabe,
Takashi Taniguchi,
Rashid Bashir,
Arend M. van der Zande,
William P. King
Publication year - 2021
Publication title -
acs omega
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.779
H-Index - 40
ISSN - 2470-1343
DOI - 10.1021/acsomega.0c05934
Subject(s) - heterojunction , monolayer , materials science , optoelectronics , photoluminescence , transistor , nanotechnology , field effect transistor , electron mobility , voltage , electrical engineering , engineering
Two-dimensional (2D) materials and heterostructures are promising candidates for nanoelectronics. However, the quality of material interfaces often limits the performance of electronic devices made from atomically thick 2D materials and heterostructures. Atomic force microscopy (AFM) tip-based cleaning is a reliable technique to remove interface contaminants and flatten heterostructures. Here, we demonstrate AFM tip-based cleaning applied to hBN-encapsulated monolayer MoS 2 transistors, which results in electrical performance improvements of the devices. To investigate the impact of cleaning on device performance, we compared the characteristics of as-transferred heterostructures and transistors before and after tip-based cleaning using photoluminescence (PL) and electronic measurements. The PL linewidth of monolayer MoS 2 decreased from 84 meV before cleaning to 71 meV after cleaning. The extrinsic mobility of monolayer MoS 2 field-effect transistors increased from 21 cm 2 /Vs before cleaning to 38 cm 2 /Vs after cleaning. Using the results from AFM topography, photoluminescence, and back-gated field-effect measurements, we infer that tip-based cleaning enhances the mobility of hBN-encapsulated monolayer MoS 2 by reducing interface disorder. Finally, we fabricate a MoS 2 field-effect transistor (FET) from a tip-cleaned heterostructure and achieved a device mobility of 73 cm 2 /Vs. The results of this work could be used to improve the electrical performance of heterostructure devices and other types of mechanically assembled van der Waals heterostructures.