Pressure sensitivity of piezoresistive nickel–carbon Ni:a-C:H thin films

The piezoresistive effects of nickel–carbon thin films, i.e., the sensitivity to hydrostatic pressure and uniform strain, are investigated in this study. Thin films, which were obtained by reactive sputtering processes with thicknesses up to 1200 nm, exhibit pressure sensitivity coefficients (PCR) about −20 ppm/bar and gauge factors up to 30 on Si/SiO2 substrates. A linear change of the thin film's resistance in respect to the applied hydrostatic pressure was observed. Additionally, the temperature coefficients of resistance were determined in the range of −300 to 0 ppm/K, while the temperature coefficient of the PCRs was obtained as good as 0 ppm/K.