High-performance double-gate α-InGaZnO ISFET pH sensor using a HfO2 gate dielectric

Chih Hung Lu, Tuo-Hung Hou, Tung Ming Pan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


In this paper, we present a high-performance double-gate (DG) amorphous indium-gallium-zinc-oxide (α-InGaZnO) ion-sensitive field-effect transistor (ISFET) using three HfO2 gate dielectric thicknesses as a top gate (TG). The DG structure α-InGaZnO TFTs with a 40-nm TG HfO2 dielectric exhibited a small threshold voltage of 50 mV, a low subthreshold swing of 144.1 mV/decade, and a high ION/IOFF current ratio of 4.5×107. The α-InGaZnO ISFET prepared at the 40-nm HfO2 sensing membrane in the DG mode showed a pH sensitivity of 937 mV/pH, which is far more than the Nernst limit. The hysteresis and drift behaviors of DG ISFET fabricated with the 40-nm condition also showed relatively better chemical stability compared with other conditions.

Original languageEnglish
Pages (from-to)237-242
Number of pages6
JournalIEEE Transactions on Electron Devices
Issue number1
StatePublished - Jan 2018


  • Double-gate (DG)
  • HfO
  • Indium-gallium- zinc-oxide (InGaZnO)
  • Ion-sensitive field-effect transistor (ISFET)
  • Top gate (TG)
  • pH sensitivity


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