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Contact Engineering of Layered MoS 2 via Chemically Dipping Treatments
Author(s) -
Bang Seungho,
Lee Sangyeob,
Rai Amritesh,
Duong Ngoc Thanh,
Kawk Iljo,
Wolf Steven,
Chung ChoongHeui,
Banerjee Sanjay K.,
Kummel Andrew C.,
Jeong Mun Seok,
Park Jun Hong
Publication year - 2020
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202000250
Subject(s) - materials science , ohmic contact , x ray photoelectron spectroscopy , contact resistance , schottky barrier , annealing (glass) , semiconductor , field effect transistor , schottky diode , optoelectronics , nanotechnology , quantum tunnelling , surface modification , transistor , layer (electronics) , chemical engineering , composite material , electrical engineering , diode , voltage , engineering
The performance of electronic/optoelectronic devices is governed by carrier injection through metal–semiconductor contact; therefore, it is crucial to employ low‐resistance source/drain contacts. However, unintentional introduction of extrinsic defects, such as substoichiometric oxidation states at the metal–semiconductor interface, can degrade carrier injection. In this report, controlling the unintentional extrinsic defect states in layered MoS 2 is demonstrated using a two‐step chemical treatment, (NH 4 ) 2 S(aq) treatment and vacuum annealing, to enhance the contact behavior of metal/MoS 2 interfaces. The two‐step treatment induces changes in the contact of single layer MoS 2 field effect transistors from nonlinear Schottky to Ohmic behavior, along with a reduction of contact resistance from 35.2 to 5.2 kΩ. Moreover, the enhancement of I ON and electron field effect mobility of single layer MoS 2 field effect transistors is nearly double for n‐ branch operation. This enhanced contact behavior resulting from the two‐step treatment is likely due to the removal of oxidation defects, which can be unintentionally introduced during synthesis or fabrication processes. The removal of oxygen defects is confirmed by scanning tunneling microscopy and X‐ray photoelectron spectroscopy. This two‐step (NH 4 ) 2 S(aq) chemical functionalization process provides a facile pathway to controlling the defect states in transition metal dichalcogenides (TMDs), to enhance the metal‐contact behavior of TMDs.