Optimum gate workfunction for v th-Controllable four-terminal-driven double-gate MOSFETs (4T-XMOSFETs) - Band-edge workfunction versus midgap workfunction

Meishoku Masahara, Shin Ichi O'Uchi, Yongxun Liu, Kunihiro Sakamoto, Kazuhiko Endo, Takashi Matsukawa, Toshihiro Sekigawa, Hanpei Koike, Eiichi Suzuki

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

We investigated the optimum gate workfunction (φ m) for four-terminal-driven double-gate MOSFETs (4T-XMOSFETs) using device simulation. Threshold voltage (V th) controllability for the 4T-XMOSFETs was investigated in relation to the initial V th in the double-gate mode (V thDG) based on comprehensible modeling of the devices. It was shown that I-V characteristics for the 4T-XMOSFETs are categorized into two states while V thDG forms a boundary. If V g2 is less than V thDG, i.e., V thSG is larger than V thDG, subthreshold-slope (S) keeps low value. If V g2 is larger than V thDG, i.e., V thSG is less than V thDG, S significantly deteriorates. As a result, setting V thDG, i.e., φ m at a low value and thus using V thSG larger than V thDG, is preferable for improving the 4T-XMOSFET performance. To confirm it, both static and dynamic characteristics for CMOS with low (band-edge) φ mmn = 4.17 eV for NMOS, φ mp = 5.25 eV for PMOS) were compared with that with high (mid-gap) φ mmn= φ mp = 4.71 eV) DGs. It was found that CMOS 4T-XMOSFET with low (band-edge) φ m DGs showed a higher I on and a shorter inverter delay than that with high (midgap) φ m DGs.

Original languageEnglish
Pages (from-to)716-721
Number of pages6
JournalIEEE Transactions on Nanotechnology
Volume5
Issue number6
DOIs
Publication statusPublished - 2006 Nov 1
Externally publishedYes

Keywords

  • Band-edge workfunction
  • CMOS inverter
  • Four-terminal-driven double-gate MOSFET
  • Gate workfunction
  • Midgap workfunction
  • V controllability
  • xMOSFET

ASJC Scopus subject areas

  • Computer Science Applications
  • Electrical and Electronic Engineering

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