Characterization of an Acetone Detector Based on a Suspended WO3-Gate AlGaN/GaN HEMT Integrated With Microheater

A suspended AlGaN/GaN high electron mobility transistor (HEMT) sensor with a tungsten trioxide (WO₃) nanofilm modified gate was microfabricated and characterized for ppm-level acetone gas detection. The sensor featured a suspended circular membrane structure and an integrated microheater to select the optimum working temperature. High working temperature (300°C) increased the sensitivity to up to 25.7% and drain current change I_DS to 0.31 mA for 1000-ppm acetone in dry air. The transient characteristics of the sensor exhibited stable operation and good repeatability at different temperatures. For 1000-ppm acetone concentration, the measured response and recovery times reduced from 148 and 656 to 48 and 320 s as the temperature increased from 210 °C to 300 °C. The sensitivity to 1000-ppm acetone gas was significantly greater than the sensitivity to ethanol, ammonia, and CO gases, showing low cross-sensitivity. These results demonstrate a promising step toward the realization of an acetone sensor based on the suspended AlGaN/GaN HEMTs.

I. Introduction

Acetone as a volatile, flammable, and irritant odor organic solvent has been extensively used in industrial applications, particularly in the pharmaceutical industry and for pesticide preparation. In addition, long-term exposure to high concentrations of acetone (more than 1000 ppm) may endanger human health, causing headache, fatigue, coma, and even death [1]. Therefore, the detection of acetone concentration is an urgent and crucial matter, especially in view of public safety and human health.