Wide-range (0.33%-100%) 3C-SiC resistive hydrogen gas sensor development

Silicon carbide (SiC) resistive hydrogen gas sensors have been fabricated and tested. NiCr planar ohmic contacts were deposited on both a 4 mum 3C-SiC epitaxial film grown on n-type Si(001) and directly on Si to form the resistive sensor structures. Detection at concentrations as low as 0.33% and as high as 100% (H-2 in Ar) was observed with the 3C-SiC sensor while the Si sensor saturated at 40%. The 3C-SiC sensors show a remarkable range of sensitivity without any saturation effects typically seen in other solid-state hydrogen gas sensors. Under a constant 2 V bias, these sensors demonstrated an increase in current up to 17 mA upon exposure to pure H-2. Preliminary experiments aimed at determining the gas sensing mechanism of these devices have been conducted and are also reported. (C) 2004 American Institute of Physics.