High-temperature Characteristic Study of Pt/AlN/SiC SBD Hydrogen Sensor

This paper presents a comprehensive investigation of a novel metal-insulator-silicon carbide Schottky barrier diode (MISiC SBD) hydrogen sensor incorporating an AlN insulating layer. The sensor’s performance was systematically evaluated under varying hydrogen concentrations and elevated temperatures. The results demonstrate that the change in SBH increases rapidly at low hydrogen concentrations but saturates at higher levels due to the limited availability of adsorption sites. Notably, at 573 K, the barrier height change was observed to be 32% higher than that at 773 K, indicating a significant temperature dependence. The current-voltage (I-V) characteristics revealed that the sensor current increases with hydrogen concentration and decreases with both temperature and insulating layer thickness. Specifically, the sensor exhibited a sensitivity ranging from 20% to 80% and a current resolution between 0.4 mA and 2 mA under tested conditions. Furthermore, the thickness of the AlN insulating layer was identified as a critical parameter influencing sensor performance. Optimization studies showed that an AlN layer thickness between 1.45 nm and 2.32 nm offers the best compromise between high sensitivity and sufficient current resolution. Additionally, the sensor displayed excellent linearity in current response for hydrogen concentrations above 200 ppm, with a maximum error of only 4 × 10−3 mA, making it suitable for practical applications such as hydrogen leakage detection. These findings confirm the effectiveness of the proposed Pt/AlN/SiC SBD structure as a highly responsive and reliable hydrogen sensor for high-temperature environments.