MOS-junction-based nanostructures by thermal oxidation of silicon wires for hydrogen detection

Heavily p-doped monocrystalline silicon wires have been fabricated by employing isotropic Si wet etch and thermal oxidation to achieve a nanometric cross section-a gate-oxide growth and a final palladium evaporation made up the MOS junction able to detect hydrogen concentration in air. Several types of wire dimensions have been designed and fabricated: length ranges from 5 to 70 μm; the smallest widths obtained are around 250-300 nm, while the biggest are up to 7 μm. Preliminary experimental results show a high signal/noise ratio sensor response to 100 ppm concentration of H₂ at room temperature, 1-atm air.