Thick film Au-gate field-effect devices sensitive to NO2

Screen printed thick film gold gate MOS capacitors are selectively sensitive to the presence of NO2 in air. Metallo-organic gold inks produce open gate structures, with positive flat-band-voltage shifts of 2.72 mV/ppm at 140 ppm of NO2 in air, comparable to PVD deposited thin film devices. Standard gold pastes are denser, coarser grained thick films of alloyed composition, which reverse the polarity of the flat-band-voltage shift. No cross sensitivity to H2 or NO is apparent.