Thin films of Pd/Ni alloys for detection of high hydrogen concentrations

Abstract

Thin alloy films of Pd and Ni (8%<Ni<20% in at. %) formed by dual-electron-beam evaporation techniques have been found to give durable and quickly reversible detectors of high H2 concentrations (pH2 0.1%–100%, 0.7–700 Torr) near 1 atm and 300 K, including accurate determinations of pH2 around the lower explosive limit of 4% in air. The addition of Ni suppresses the α to β phase transition found in pure Pd under these conditions. The measurement of resistivity changes in the thin films along with flatband shifts of metal-oxide-semiconductor capacitors on the same Si wafer gives accurate values of pH2 over more than six decades.