High Selectivity Hydrogen Gas Sensor Based on WO3/Pd-AlGaN/GaN HEMTs

Abstract

We investigated the hydrogen gas sensors based on AlGaN/GaN high electron mobility transistors (HEMTs) for high temperature sensing operation. The gate area of the sensor was functionalized using a 10 nm Pd catalyst layer for hydrogen gas sensing. A thin WO3 layer was deposited on top of the Pd layer to enhance the sensor selectivity toward hydrogen gas. At 200 °C, the sensor exhibited high sensitivity of 658% toward 4%-H2, while exhibiting only a little interaction with NO2, CH4, CO2, NH3, and H2S. From 150 °C to 250 °C, the 10 ppm hydrogen response of the sensor was at least eight times larger than other target gases. These results showed that this sensor is suitable for H2 detection in a complex gas environment at a high temperature.

A Review of Hydrogen Sensors for ECLSS: Fundamentals, Recent Advances, and Challenges

“…The lack of timely and effective means of hydrogen monitoring will seriously threaten both astronauts' lives and the safety of manned spacecraft cabin equipment. The hydrogen sensor is a sensing device that detects the concentration of hydrogen and generates a response signal, which has the advantages of small size, low cost, online measurement, and short response time compared to traditional detection instruments [1][2][3][4][5][6]. Therefore, the development of hydrogen sensors with a high detection accuracy, a fast response time, a long calibration period, and good stability has become the focus of regenerative life support technology design.…”

Response Surface Modeling of the Steady-State Impedance Responses of Gas Sensor Arrays Comprising Functionalized Carbon Nanotubes to Detect Ozone and Nitrogen Dioxide

“…The predominant gas sensing technologies are conductimetric, capacitive, gravimetric (e.g., quartz crystal microbalance), surface acoustic wave resonators, colorimetric, optical spectroscopy, UV absorbance, photoionization detection, electrochemical (EC), heated metal oxide semiconductors (HMOS), and carbon nanotubes (CNTs) [31][32][33][34]. Of these methods, low-cost commercial gas sensors for environmental monitoring [35][36][37][38] mostly employ EC [39][40][41][42][43][44][45][46][47] and HMOS [48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63] methods.…”

“…Cross-sensitivity to other oxidizing gases remains a major problem in the detection of environmental pollutants, such as O 3 and NO 2 , wherein low levels (below 100 ppb) need to be measured. Ozone and nitrogen dioxide are oxidizing gases with similar chemical affinity and produce nonspecific responses in EC [42][43][44][45][46], HMOS [48][49][50][51][57][58][59], as well as nanotechnology-based [97] sensors. Cross-sensitivity to the interfering gas decreases the selectivity to the target gas.…”