Low power hydrogen sensors using electrodeposited PdNi–Si schottky diodes

• Published in: Procedia engineering Vol. 5; pp. 143 - 146
• Main Authors: Usgaocar, A.R., de Groot, C.H., Boulart, Cedric, Castillo, Alain, Chavagnac, Valérie
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 2010
• ISSN: 1877-7058; 1877-7058
• DOI: 10.1016/j.proeng.2010.09.068

The use of electrodeposited PdNi–Si Schottky barriers as low power Hydrogen sensors is investigated. The Palladium content of the film causes the Hydrogen molecules to dissociate and be absorbed by the film, changing the metal work function and Schottky barrier current. Electrodeposited PdNi–Si Schottky barriers exhibit very low reverse bias current and in a back to back configuration form a device that draws extremely low power when idle. The Schottky diodes were fabricated on 0.5–1.5 Ω cm 100 n-type Si by electrodeposition of PdNi followed by evaporation of Aluminium contact pads. Electrical measurements at different Hydrogen pressures were performed on back to back Schottky diodes in a vacuum chamber using pure Nitrogen and a 5% Hydrogen-Nitrogen mixture. Very low currents of ≈1nA were measured in the absence of Hydrogen. Large increases in the currents, upto a factor of 100, were observed upon exposure to different Hydrogen partial pressures. The highest sensitivity was estimated to be 17.27 nA/mbar. The low idle current, simplicity of the fabrication process and ability to easily integrate with conventional electronics proves the suitability of electrodeposited PdNi–Si Schottky barriers as low power Hydrogen sensors.