Effect of sensing film thickness on sensing characteristics of dual-gate poly-si ion-sensitive field-effect-transistors

Li Chen Yen*, Ming Tsyr Tang, Chia Ying Tan, Tung Ming Pan, Tien-Sheng Chao

*Corresponding author for this work

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

We investigate the effect of sensing film thickness on the sensing characteristics of dual-gate (DG) poly-Si ion-sensitive field-effect transistors (ISFETs). The pH sensitivity (from 37.57 to 9.32 mV/pH) of the DG poly-Si ISFET device degrades with the increase in the sensing film thickness (from 20 to 120 nm), whereas hysteresis voltage (from 6.7 to 1.12 mV for a neutral to acid to alkaline to neural loop) and drift rate (from 13.47 to <3 mV/h at pH 7) improve accordingly. An improved hysteresis and drift phenomena are attributed to the reduction in top-gate capacitance of the sensing membrane, causing a smaller capacitive-coupling ratio (top-gate capacitance of sensing membrane to bottom-gate capacitance of tetraethylorthosilicate oxide).

Original languageEnglish
Article number6954697
Pages (from-to)1302-1304
Number of pages3
JournalIEEE Electron Device Letters
Volume35
Issue number12
DOIs
StatePublished - 1 Dec 2014

Keywords

  • Drift, dual-gate (DG)
  • hysteresis
  • ion-sensitive field-effect transistor (ISFET)
  • poly-Si
  • sensitivity

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