(Invited) Poly-Si TFT Based Technologies and Circuits for Multipurpose Sensors

Abstract

Many works were performed to develop CMOS like circuits with both types (NMOS and PMOS) thin film transistors (TFT), by improving the deposition techniques, the doping control and the crystallization of the deposited films to reach the highest performances and reliability. These results opened the spectrum of applications of large area electronics, on glass substrate. Among them, sensors are the most concerned. This paper presents several approaches involving TFT that lead to specific sensors. The first one concerned a dedicated TFT including two Hall contacts, a MAGFET. The second one consists to suppress the deposited gate oxide and to leave a free space that can store charges permanently or temporary. Thus, polysilicon TFTs with a suspended gate (SGTFT) were fabricated, the airgap under the gate bridge accepting charges in a very small volume. On the base of this generic structure, several sensors were developed more especially pH-meter, proteins and DNA sensors.