ISFET's Using Inorganic Gate Thin Films

Hiroshi Abe, Masayoshi Esashi, Tadayuki Matsuo

Research output: Contribution to journalArticle

153 Citations (Scopus)


The characteristics of various types of ISFET's using inorganic gate films are described. The pH and pNa selectivities are investigated for SiO2, Si3N4, A12O3, alumino-silicate, and sodiumalumino-silicate gate dielectrics. The transient response and device stability are also studied for different values of solution pH. The Al2O3 gate shows a nearly ideal pH response, excellent stability, and selectivity to other cations. On the other hand, the Si3N4 gate is also a good pH sensor, but it is proved by the studies of SiO2 and SiOxNy films that the oxygen content in its surface degrades its properties as a pH sensor. Sodium-alumino-silicate, which is generally known as a material for pNa selective glass electrodes, is utilized as a gate film for the pNa ISFET. The pNa selectivity of this device is comparable to that of the conventional glass electrode. The alumino-silicate gate has also a pNa selectivity, but iti s inferior to the sodium-alumino-silicate gate.

Original languageEnglish
Pages (from-to)1939-1944
Number of pages6
JournalIEEE Transactions on Electron Devices
Issue number12
Publication statusPublished - 1979 Dec

ASJC Scopus subject areas

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

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