Zinc Oxide Thin-Film Transistor with Catalytic Electrodes for Hydrogen Sensing at Room Temperature

Abstract

Palladium-Titanium (Pd-Ti)/n-ZnO Schottky contact based thin-film transistor (TFT) was fabricated on a thermally oxidized n-Si substrate with a compatible fabrication process and the hydrogen-sensing response was evaluated under room temperature (RT) without the presence of any heating element which reduces design complexity as well as power consumption significantly. Structural, mechanical, chemical and optical properties of the RF (Radio Frequency) sputtered ZnO thin film with 150 nm thickness as a gas sensing element have been investigated. Electrical characteristics and concentration dependent (500 ppm to 4500 ppm) RT sensor response (in the context of increasing drain current as the Schottky barrier height decreases) of the fabricated device with the maximum sensitivity of 70.8% (at 4500 ppm H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) including a minimum response time of 20 s (at 4500 ppm H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) and recovery time of 40 s (at 500 ppm H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) have been demonstrated. Sufficiently impressive performance of the sensor has been observed with respect to repeatability, selectivity, time-depending stability and humidity analysis at RT.