SiC-based FET for detection of NOx and O2 using InSnOx as a gate material

We have fabricated depletion-mode 4H–SiC field effect transistors (FETs) for use as gas sensors. To enable sensitivity to NOx and O2 gases, a mixture of indium oxide (InOx) and tin oxide (SnOx) was deposited by rf magnetron reactive sputtering as a gate material. The chemical composition of the deposited film was examined using Auger electron spectroscopy (AES) combined with depth profiling analysis. The response to NOx and O2 gases was investigated as a function of operating temperature for different concentrations of the test gas. The maximal response to NOx and O2 was observed at 350 and 400 °C, respectively.