Evaluation of hydrogen-sensitive switching device by capacitance-voltage method

Abstract

Abstract To investigate the hydrogen-sensitive switching properties of a device with a Pd-insulator-(n)Si-(p + )Si structure, four devices with different thicknesses of either the Pd electrode or the insulator layer have been fabricated and subjected to measurements of the current-voltage ( I – V ) and capacitance-voltage ( C - V ) characteristics in an atmosphere containing various concentrations of H 2 in air. The I – V characteristics reveal negative-resistance switching properties with the switching voltage being dependent on the hydrogen gas concentration and the device used. The work function of Pd, estimated from the C - V characteristics, decreases with increasing hydrogen concentration, almost independent of the device used. It is shown that the change of Pd work function upon exposure to H 2 can induce an effective decrease in switching voltage when the Pd electrode and the insulator layer are sufficiently thin and thick, respectively. These phenomena are explained by assuming the formation of recombination centres in the insulator layer.