Evolution of Structure and Electrical Characteristics of Pt/WOx/6H-SiC Sensor Upon Exposure to H2 Gas at High Temperature

The bilayer film Pt/WOx was deposited by pulsed laser ablation on a silicon carbide monocrystal plate (6H-SiC) to form an H2 sensor for high temperature application. The study demonstrates high sensitivity of the Pt/WOx/SiC structure to a low H2 concentration. For 0.2 H2% in air at 350 °C, the shift of voltage on the reverse branch of the current-voltage characteristic reached 6.5 V at a current of 0.4 μA. After the high temperature interaction with H2, the sample can confine hydrogen atoms in the WOх layer at room temperature for a long time. The study explores the influence of operation conditions as well as the H2 action on the structure and electrical characteristics of the layers in the system. Phase transformation of the crystalline structure of the WOx film due to hydrogen penetration was detected and this process initiated pronounced electrical properties changes.