On the voltage dependence of sensitivity for Schottky-type gas sensor

The voltage dependence of sensitivity for Schottky-diode gas sensor is theoretically studied and experimentally verified in this work. The study is based on the forward current-voltage (I-V) characteristics of the device and benefits from its power exponent parameter α (V) = [d(ln I)]/[d(ln V)]. This proposed analytical method (1) provides an easier way to identify the current-flow mechanisms at different bias levels, (2) demonstrates the exponential relation between the device sensitivity and the voltage at low bias level, (3) allows easy and accurate calculation of the Schottky barrier-height change, and (4) lays the groundwork for investigating the maximum sensitivity and the corresponding bias voltage. This analytical method is verified by using a Pd/WO3/SiC diode under exposure to hydrogen gas with different concentrations at 150 °C and 225 °C. Based on the proposed method, the parameters (barrier-height change, maximum sensitivity and corresponding bias voltage) of the sensor can be easily extracted and show excellent consistence with those obtained by conventional method.