Tungsten-oxide thin films for a high-temperature semiconductor hydrogen detector based on a 6H-SiC crystal

Abstract

We demonstrate the possibility of fabricating high-efficiency semiconductor hydrogen detectors based on tangsten-oxide thin films deposited onto silicon-carbide crystals by reactive pulsed-laser deposition. The obtained WO₃/SiC structures ensure a noticeable voltage shift ΔU on the reverse branch of the I−V characteristics without commonly used catalyst layers of platinum-group metals. The ΔU value reached 2.1 V at a detected hydrogen concentration of 0.2% in air at 350°C. The response times to hydrogen inlet and recovery of the WO₃/SiC structure after hydrogen outlet are found to be much shorter than those for the Pt/WO₃/SiC structure. The high performances of the fabricated WO₃/SiC sensor are due to the layered structure of the orthorhombic phase of tungsten oxide, which consists of loosely packed microcrystalline plates containing nanocrystals smaller than 100 nm.