Study on the amorphous tungsten trioxide ion-sensitive field effect transistor

In this study, the pH-sensitive properties of the amorphous tungsten trioxi de (a-WO3) thin films by the RF sputtering system from a WO3 target have be en investigated. The electrolyte-insulator-semiconductor (EIS) structure wi th a-WO3 thin film can be used to detect the sensitivity of ion and can be explained by the C-V curve in the different acidic buffer solutions (pH = 1 -7) using the C-V measurement. In addition, the tungsten trioxide thin film s were also deposited on the double layer structure of a-WO3/SiO2 gate ion- sensitive field effect transistor (ISFET), and could obtain the shift of th e linear region threshold voltage (Delta V-T) of the ISFET devices in the a cidic solutions. The a-WO3 materials exhibit a fairly high response, and th e sensitivity is obtained at about 50 mV/pH. (C) 2000 Elsevier Science S.A. All rights reserved.