Autonomous refresh of floating-body cell due to current anomaly of impact ionization

Takashi Ohsawa*, Ryo Fukuda, Tomoki Higashi, Katsuyuki Fujita, Fumiyoshi Matsuoka, Tomoaki Shino, Hironobu Furuhashi, Yoshihiro Minami, Hiroomi Nakajima, Takeshi Hamamoto, Yohji Watanabe, Akihiro Nitayama, Tohru Furuyama

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


Physics of autonomous refresh is presented, which explains the mechanism of a spontaneous recovery of degraded binary states of the floating-body cell (FBC). Input current to the floating body and output current from the body balance to generate an unstable stationary state that is accompanied by two stable stationary ones. The current anomaly of impact ionization is essential for the instability that brings about the bistability and is realized by positive feedback where impact ionization current input increases as the body voltage increases. Experiments with charge pumping current as output show that the autonomous refresh is possible on a single-cell basis. Necessary conditions for a high-density memory to be autonomously refreshed are derived and assessed for state-of-the-art FBCs. FBC is shown in simulation to become an SRAM cell when the autonomous refresh is applied, which uses gate direct tunneling current as output. This is an SRAM cell that is theoretically expected to have the simplest structure ever reported.

Original languageEnglish
Pages (from-to)2302-2311
Number of pages10
JournalIEEE Transactions on Electron Devices
Issue number10
Publication statusPublished - 2009
Externally publishedYes


  • Autonomous refresh
  • Capacitorless 1T-DRAM
  • Charge pumping
  • Data retention current
  • Floating-body cell (FBC)
  • Gate direct tunneling
  • Impact ionization
  • SRAM

ASJC Scopus subject areas

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


Dive into the research topics of 'Autonomous refresh of floating-body cell due to current anomaly of impact ionization'. Together they form a unique fingerprint.

Cite this