Improved CO gas detection of Si MOSFET gas sensor with catalytic Pt decoration and pre-bias effect

Abstract

This paper investigates carbon monoxide (CO) gas sensing performance in a silicon metal-oxide semiconductor field effect transistor (Si MOSFET)-based gas sensor having a structure in which a floating-gate (FG) and a control-gate (CG) are interdigitated in a horizontal direction. The sensing material, indium oxide (In2O3) nanoparticles, is formed by an inkjet printing process between the FG covered with an insulator stack and exposed CG. Decorating the sensing layer with catalytic Pt and applying pulsed pre-bias are introduced as a method to improve CO gas sensing characteristics of the MOSFET sensor. First, CO gas sensing performance with Pt concentration and operating temperature is studied. The sensing performance is measured at 200 °C mainly by applying pulses to the CG. The response, response and recovery times of the MOSFET sensor are significantly enhanced with catalytic Pt decoration. In this work, 5% Pt decoration shows the best sensing characteristics. Response and recovery times are improved by 65% and 70%, by applying a pre-bias of 2 V and −2 V to the CG during response and recovery, respectively.