High temperature sensors based on silicon carbide (SiC) devices

SiC devices´ electrical properties used as sensing mechanisms are demonstrated for two types of sensors. A Schottky barrier diode (SBD) is proposed as a temperature sensor while a MOS capacitor is used for gas (hydrogen) detection. A layout with different active contacts, having 200, 300 and 400μm diameters and similar technology is designed and used for fabricating both sensors. An automatic high temperature system is developed to test the sensors up to 450°C. The main electrical parameters of the SiC devices designed to operate as sensors are extracted using dedicated programs. The temperature detection sensitivity of the SBD is in range of 1.52-2.13mV/°C. For the gas sensor, a sensitivity peak of 120% is achieved for a H₂ concentration over 1000 ppm. An industrial temperature probe based on SiC SBD was tested to monitor furnace temperature in the 100-400°C range in a cement factory.