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

doi:10.1109/TED.2018.2888598

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 publication › Journal article › Academic research › peer-review

10 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 language	English
Article number	8603764
Pages (from-to)	1107-1112
Number of pages	6
Journal	IEEE Transactions on Electron Devices
Volume	66
Issue number	2
DOIs	https://doi.org/10.1109/TED.2018.2888598
Publication status	Published - 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

More information

10.1109/TED.2018.2888598

Cite this

@article{3fcbfb9d767e47b89171390e1d528f76,

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

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. ",

keywords = "Charged impurity (CI) scattering, high-κ encapsulation, mobility, MoS FET, trapped charges",

author = "Xu, {Jing Ping} and Xie, {Wen Xuan} and Lu Liu and Xinyuan Zhao and Xingjuan Song and Lai, {Pui To} and Tang, {Wing Man}",

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Effects of trapped charges in gate dielectric and high-κ encapsulation on performance of MoS ₂ transistor. / Xu, Jing Ping; Xie, Wen Xuan; Liu, Lu et al.
In: IEEE Transactions on Electron Devices, Vol. 66, No. 2, 8603764, 01.02.2019, p. 1107-1112.

Research output: Journal article publication › Journal article › Academic research › peer-review

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AU - Xu, Jing Ping

AU - Xie, Wen Xuan

AU - Liu, Lu

AU - Zhao, Xinyuan

AU - Song, Xingjuan

AU - Lai, Pui To

AU - Tang, Wing Man

PY - 2019/2/1

Y1 - 2019/2/1

N2 - 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.

AB - 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.

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