Errors of Integrated Hydrogen Sensors Based on FETs with Structure Pd (Ag)–Ta2O5–SiO2–Si

Abstract

The object of the study was an integrated sensor’s cell consisting of n-channel FET-sensor element based on Pd(Ag)–Ta2O5–SiO2–Si structure, fabricated on Si-chip together with heater-resistor and temperature sensor by means of conventional n-MOS-technology using laser evaporation Pd(Ag)-films. Estimation of hydrogen concentration measurement’s errors by FET-sensors has been done, using the models based on the experimental data. Proposed models of absolute and relative errors include components that take into account the instrumental errors of measurement units; the random errors associated with dispersions of sensors’ output voltages; fluctuations of chip temperature and electrical circuits’ parameters; additional errors due to the influence of other gases and radiation. It is shown how the errors depend on sensor sensitivity, hydrogen concentrations and total hydrogen dose. Examples of how to estimate the threshold of sensitivity and the operating range of concentration measurements for a given relative error are presented.