Capacitance-voltage analysis of electrical properties for WSe2 field effect transistors with high-k encapsulation layer

Seung Pil Ko, Jong Mok Shin, Ho Kyun Jang, Min Youl You, Jun Eon Jin, Miri Choi, Jiung Cho, Gyu-Tae Kim

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Doping effects in devices based on two-dimensional (2D) materials have been widely studied. However, detailed analysis and the mechanism of the doping effect caused by encapsulation layers has not been sufficiently explored. In this work, we present experimental studies on the n-doping effect in WSe2 field effect transistors (FETs) with a high-k encapsulation layer (Al2O3) grown by atomic layer deposition. In addition, we demonstrate the mechanism and origin of the doping effect. After encapsulation of the Al2O3 layer, the threshold voltage of the WSe2 FET negatively shifted with the increase of the on-current. The capacitance-voltage measurements of the metal insulator semiconductor (MIS) structure proved the presence of the positive fixed charges within the Al2O3 layer. The flat-band voltage of the MIS structure of Au/Al2O3/SiO2/Si was shifted toward the negative direction on account of the positive fixed charges in the Al2O3 layer. Our results clearly revealed that the fixed charges in the Al2O3 encapsulation layer modulated the Fermi energy level via the field effect. Moreover, these results possibly provide fundamental ideas and guidelines to design 2D materials FETs with high-performance and reliability.

Original languageEnglish
Article number065703
JournalNanotechnology
Volume29
Issue number6
DOIs
Publication statusPublished - 2018 Jan 10

Keywords

  • Doping effects
  • field effect transistors
  • high-k encapsulation layer (AlO)
  • WSe

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering
  • Electrical and Electronic Engineering

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