Understanding Coulomb Scattering Mechanism in Monolayer MoS2 Channel in the Presence of h-BN Buffer Layer

Min Kyu Joo, Byoung Hee Moon, Hyunjin Ji, Gang Hee Han, Hyun Kim, Gwanmu Lee, Seong Chu Lim, Dongseok Suh, Young Hee Lee

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

As the thickness becomes thinner, the importance of Coulomb scattering in two-dimensional layered materials increases because of the close proximity between channel and interfacial layer and the reduced screening effects. The Coulomb scattering in the channel is usually obscured mainly by the Schottky barrier at the contact in the noise measurements. Here, we report low-temperature (T) noise measurements to understand the Coulomb scattering mechanism in the MoS2 channel in the presence of h-BN buffer layer on the silicon dioxide (SiO2) insulating layer. One essential measure in the noise analysis is the Coulomb scattering parameter (αSC) which is different for channel materials and electron excess doping concentrations. This was extracted exclusively from a 4-probe method by eliminating the Schottky contact effect. We found that the presence of h-BN on SiO2 provides the suppression of αSC twice, the reduction of interfacial traps density by 100 times, and the lowered Schottky barrier noise by 50 times compared to those on SiO2 at T = 25 K. These improvements enable us to successfully identify the main noise source in the channel, which is the trapping-detrapping process at gate dielectrics rather than the charged impurities localized at the channel, as confirmed by fitting the noise features to the carrier number and correlated mobility fluctuation model. Further, the reduction in contact noise at low temperature in our system is attributed to inhomogeneous distributed Schottky barrier height distribution in the metal-MoS2 contact region.

Original languageEnglish
Pages (from-to)5006-5013
Number of pages8
JournalACS Applied Materials and Interfaces
Volume9
Issue number5
DOIs
StatePublished - 8 Feb 2017

Bibliographical note

Funding Information:
This work was supported by the Institute for Basic Science (IBS-R011-D1) (Y.H.L.) and by the National Research Foundation of Korea (NRF-2016R1A2B2012336) (D.S.), funded by the Ministry of Science, ICT & Future Planning Republic of Korea.

Publisher Copyright:
© 2017 American Chemical Society.

Keywords

  • Coulomb scattering parameter
  • h-BN
  • low-frequency noise
  • MoS
  • Schottky barrier inhomogeneity
  • TMD

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