Fabrication and characterization of surface type Schottky diode hydrogen sensor using polyaniline/porous 3C-SiC

This paper describes the fabrication and characterization of a hydrogen sensor that uses polyaniline (PANI) nanofiber/porous 3C-SiC (PSiC) heterojunctions. In this work, a PSiC with pore diameter of 50 nm was formed from polycrystalline N-type 3C-SiC thin films by electrochemical anodization. PANI nanofibers with an average diameter of 60 nm and length of 300 nm were synthesized in compressed liquid carbon dioxide on PSiC, using the 2-step spin coating method. The electrical characteristics of PANI on PSiC heterojunction diodes were evaluated with current voltage measurements, showing a P–N junction. Hydrogen sensing properties were investigated at various temperatures with H2 concentrations ranging from 30 ppm to 150 ppm. The response decreased as the temperature increased. However, a high linearity response was shown at 100 °C with H2 concentrations. The response and recovery time was decreased at temperatures below 125 °C and unstable sensing properties were shown at 150 °C. The best performance was observed at 100 °C, with fast response and fast recovery times of 10 and 6 s, respectively.