Authors: N. Zehfroosh, M. Shahmohammdi, S. Mohajerzadeh
Affilation: University of Tehran, Iran, Islamic Republic of
Pages: 390 - 393
Keywords: ISFET, nanoporous, silicon, threshold voltage
We report the realization of ultra high sensitivity ion-selective field effect transistors (ISFET) devices by means of a nano-porous silicon structures placed on the gate region. Thanks to the presence of a nano-porous polysilicon film on the gate, the effective area of the exposed surface is numerously larger than that of the channel area. The response of such transistors to pH is essentially different from regular ISFETs where a change in threshold voltage is recorded. Depending on the measurement conditions and for a constant transistor current, a high shift in the drain-source voltage of the order of a few volts can be observed. A relative current-based sensitivity can be adopted for such devices. The proposed sensors show a superior sensitivity thanks to their 3-dimantional geometry.