Hydrogen Fluoride Gas Sensor by Silicon Nanosheet Field-Effect Transistor

Abstract

Chemical sensors are an essential part of modern society to ensure safety, from preventing pollution to saving lives. Especially, the demand for real-time monitoring of hydrogen fluoride (HF) increases continuously due to its high toxicity, contrary to its wide use in industries. In addition, compact size and low cost are favorable to utilize the sensor in wide spreading applications in industries. Herein, we present a compact HF gas sensor with high sensitivity and selectivity. The HF sensors, fabricated in the form of field-effect transistors (FETs) using a cost-effective and mass-production friendly conventional semiconductor process, are shown to possess good electrical characteristics enabled by a silicon nanosheet (SiNS) current channel. High sensitivity on gas phase HF is achieved by the unique catalytic sensing membrane -- platinum/polycrystalline lanthanum fluoride (Pt/poly-LaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ). The high responsivity ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</sub> ) of 3,071% at 25 ppm and the low limit of detection (LOD) of 219 ppb were achieved at room temperature (RT), along with a quick response time of 5.56 minutes which are crucial for the workplace environmental safety. The developed HF sensor can be a potential candidate for the industrial mobile sensor platform.