FET humidity sensors based on titanium oxide film

Humidity sensitive field effect transistors for an integrated humidity sensors have been fabricated using conventional silicon microtechnology and their hygroscopic characteristics have been investigated. We applied the lift-off techniques for 1000 /spl Aring/ TiO/sub 2/ films on gate region. The devices showed typical enhancement characteristics and threshold voltage was about 2.3 V in 60%RH. It can be seen that the threshold voltages of HUSFET decreased from 2.5 V to 2.0 V according to increasing the relative humidities from 30% to 90%. The simulation was carried out for a series of values of relative permittivity (/spl epsiv//sub r/), which was varied between 123 and 223.