We report the fabrication of a novel hydrogen sensor that utilizes the electrical resistance changes in the palladium thin films with nanometer thicknesses. The sensing mechanism is based on transitory absorption of hydrogen atoms into the palladium layer, which leads to the reversible alteration of the electrical resistance. In concentrated hydrogen ambient, the excess hydrogen absorption process leads to mechanical deformation on the surface of the palladium films, corresponding to the phase transition from α-phase to β-phase. The reversible sensing process results in a hysteresis curve for resistive properties, of which the height (sensitivity) could be controlled by manipulating the thickness of the palladium layers. The peel-off phenomena on the surface of the palladium film were suppressed by decreasing the thickness of the film. At the thickness of 20 nm, a hysteresis curve of resistance was obtained without any structural change in the palladium thin film. These results provide a significant insight to the fundamental understanding of the relationship between the electrical sensitivity of pure Pd thin films and related structural deformation, which is essential to develop robust H-sensors with high sensibility.
Bibliographical noteFunding Information:
This work was supported by the Agency for Defense Development through the Defense Nano Technology Application Center, Priority Research Centers Program ( 2009-0093823 ) through the National Research Foundation of Korea (NRF), the Basic Research Program grant ( R01-2008-000-21078-0 ), Seoul Research and Business Development Program ( 10816 ). T Lee is grateful for the System IC 2010 program of the Ministry of Knowledge Economy, and Republic of Korea ( 10030517-2009-03 , Advanced CMOS image sensor using 3D integration).
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Fuel Technology
- Condensed Matter Physics
- Energy Engineering and Power Technology