Selective-hydrogen sensing at room temperature with Pt-coated InN nanobelts

The hydrogen sensing characteristics of multiple InN nanobelts grown by metalorganic chemical vapor deposition were investigated. Pt-coated InN sensors could selectively detect hydrogen at the tens of ppm level at 25 degrees C, while uncoated InN showed no detectable change in current when exposed to hydrogen under the same conditions. Upon exposure to various concentrations of hydrogen (20-300 ppm) in N-2 ambient, the relative resistance change increased from 1.2% at 20 ppm H-2 to 4% at 300 ppm H-2. Approximately 90% of the initial InN resistance was recovered within 2 min by exposing the nanobelts to air. Temperature-dependent measurements showed larger resistance change and faster response at high temperature compared to those at room temperature due to increase in catalytic dissociation rate of H-2 as well as diffusion rate of atomic hydrogen into the Pt/InN interface. The Pt-coated InN nanobelt sensors were operated at low power levels (similar to 0.5 mW).