title: Simple Chemical Treatment to n-Dope Transition-Metal Dichalcogenides and Enhance the Optical and Electrical Characteristics.
abstract: The optical and electrical properties of monolayer transition-metal dichalcogenides (1L-TMDs) are critically influenced by two dimensionally confined exciton complexes. Although extensive studies on controlling the optical properties of 1L-TMDs through external doping or defect engineering have been carried out, the effects of excess charges, defects, and the populations of exciton complexes on the light emission of 1L-TMDs are not yet fully understood. Here, we present a simple chemical treatment method for n-dope 1L-TMDs, which also enhances their optical and electrical properties. We show that dipping 1Ls of MoS2, WS2, and WSe2, whether exfoliated or grown by chemical vapor deposition, into methanol for several hours can increase the electron density and also can reduce the defects, resulting in the enhancement of their photoluminescence, light absorption, and the carrier mobility. This methanol treatment was effective for both n- and p-type 1L-TMDs, suggesting that the surface restructuring around structural defects by methanol is responsible for the enhancement of optical and electrical characteristics. Our results have revealed a simple process for external doping that can enhance both the optical and electrical properties of 1L-TMDs and help us understand how the exciton emission in 1L-TMDs can be modulated by chemical treatments.
authors.affiliation: Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 440-746, Republic of Korea.|Department of Energy Science, Sungkyunkwan University (SKKU) , Suwon 440-746, Republic of Korea.
authors.forename: Guru P
authors.initials: GP
authors.lastname: Neupane
authors.affiliation: Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 440-746, Republic of Korea.|Department of Energy Science, Sungkyunkwan University (SKKU) , Suwon 440-746, Republic of Korea.
authors.forename: Minh Dao
authors.initials: MD
authors.lastname: Tran
authors.affiliation: Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 440-746, Republic of Korea.|Department of Energy Science, Sungkyunkwan University (SKKU) , Suwon 440-746, Republic of Korea.
authors.forename: Seok Joon
authors.initials: SJ
authors.lastname: Yun
authors.affiliation: Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 440-746, Republic of Korea.|Department of Energy Science, Sungkyunkwan University (SKKU) , Suwon 440-746, Republic of Korea.
authors.forename: Hyun
authors.initials: H
authors.lastname: Kim
authors.affiliation: Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 440-746, Republic of Korea.|Department of Energy Science, Sungkyunkwan University (SKKU) , Suwon 440-746, Republic of Korea.
authors.forename: Changwon
authors.initials: C
authors.lastname: Seo
authors.affiliation: Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 440-746, Republic of Korea.|Department of Energy Science, Sungkyunkwan University (SKKU) , Suwon 440-746, Republic of Korea.
authors.forename: Jubok
authors.initials: J
authors.lastname: Lee
authors.affiliation: Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 440-746, Republic of Korea.|Department of Energy Science, Sungkyunkwan University (SKKU) , Suwon 440-746, Republic of Korea.
authors.forename: Gang Hee
authors.initials: GH
authors.lastname: Han
authors.affiliation: Department of Physics, Indian Institute of Science , Bangalore 560012, India.
authors.forename: A K
authors.initials: AK
authors.lastname: Sood
authors.affiliation: Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 440-746, Republic of Korea.|Department of Energy Science, Sungkyunkwan University (SKKU) , Suwon 440-746, Republic of Korea.
authors.forename: Jeongyong
authors.identifier: http://orcid.org/0000-0003-4679-0370
authors.initials: J
authors.lastname: Kim
keywords: MoS2; WS2; WSe2; methanol; mobility; n-doping; photoluminescence; transition-metal dichalcogenides