Electrical and hydrogen sensing characteristics of Pd/ZnO Schottky diodes grown on GaAs

Current-voltage measurements were used to study the electrical and hydrogen sensing characteristics of Pd Schottky contacts fabricated on ZnO. The ZnO films were grown on doped GaAs by MOCVD. By utilizing the GaAs substrate as a low resistance contact to the ZnO film, a remarkably low series resistance of the diodes was achieved. After exposure of the Schottky diodes to a hydrogen ambient, the current at reverse bias increased, indicating the sensitivity to hydrogen gas. In contrast to previous reports, the contacts are able to recover fully at room temperature. Annealing studies in hydrogen ambient show stability of these contacts up to temperatures of 150 degrees C.