Achievement of controlled resistive response of nanogapped palladium film to hydrogen

Palladium (Pd) film containing nanogaps of well controlled dimension was fabricated on a Si wafer having a high-aspect-ratio micropillar. The Pd film was arranged to experience hydrogen (H2)-induced volume expansion. (i) If the nanogap is kept open, its width is narrowed down. A discharge current was generated to give a strong, fast, and repeatable on-off type resistive switching response. (ii) If the nanogap is closed, the cross section of the conduction path varies to give continuous H2-concentration dependent resistive response. The influence of stresses and related physical mechanisms are discussed.