Effects of trapped charges in gate dielectric and high-κ encapsulation on performance of MoS 2 transistor

Jing Ping Xu, Wen Xuan Xie, Lu Liu, Xinyuan Zhao, Xingjuan Song, Pui To Lai, Wing Man Tang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

3 Citations (Scopus)

Abstract

The effects of trapped charges in gate dielectric and high-k encapsulation layer on the performance of MoS 2 transistor are investigated by using SiO 2 with different thicknesses as the gate dielectric and HfO 2 as the encapsulation layer of the MoS 2 surface. Results indicate that the positive trapped charges in SiO 2 can increase the electrons in MoS 2 for screening the scattering of charged impurity (CI) in SiO 2 and at the SiO 2 /MoS 2 interface to increase the carrier mobility. However, the CI scattering becomes stronger for thicker gate dielectric with more trapped charges and can dominate the electron screening effect to reduce the mobility. On the other hand, with the HfO 2 encapsulation, the OFF-currents of the devices greatly increase and their threshold voltages shift negatively due to more electrons induced by more positive charges trapped in HfO 2 . Moreover, the screening effect of these electrons on the CI scattering results in a mobility increase, which increases with the magnitude of the CI scattering. A 51% improvement in mobility is obtained for the sample suffering from the strongest CI scattering, fully demonstrating the effective screening role of high-k dielectric on the CI scattering.

Original languageEnglish
Article number8603764
Pages (from-to)1107-1112
Number of pages6
JournalIEEE Transactions on Electron Devices
Volume66
Issue number2
DOIs
Publication statusPublished - 1 Feb 2019

Keywords

  • Charged impurity (CI) scattering
  • high-κ encapsulation
  • mobility
  • MoS FET
  • trapped charges

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

Cite this