Room temperature hydrogen detection using Pd-coated GaN nanowires

Abstract

Multiple GaN nanowires produced by thermal chemical vapor deposition were employed as gas sensors for detection of hydrogen at concentrations from 200–1500 ppm in N2 at 300 K. Palladium coating of the wires improved the sensitivity by a factor of up to 11 at low ppm concentrations relative to uncoated controls. The GaN nanowires showed relative responses of ∼7.4% at 200 ppm and ∼9.1% at 1500 ppm H2 in N2 after a 10 min exposure. Upon removal of hydrogen from the measurement ambient, ∼90% of the initial GaN conductance was recovered within 2 min. Temperature dependent measurements showed a larger relative response and shorter response time at elevated temperature. The adsorption activation energy of the sensor was 2.2 kcal mol−1 at 3000 ppm H2 in N2. These sensors exhibit low power consumption (<0.6 mW) at 300 K.

Moisture Insensitive PMMA Coated Pt-AlGaN/GaN Diode Hydrogen Sensor and Its Thermal Stability

“…[4][5][6] Among semiconductor-based hydrogen sensors, various types of wide bandgap GaN (3.4 eV) thin film or nanostructured devices contacted with Pt-or Pd-gate metals are attractive for their robustness and wide operating temperature. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] In particular, the availability of piezoelectric AlGaN/GaN heterostructures enables the design of transistor-based sensors with enhanced sensitivity. 8,9,20,[22][23][24] The AlGaN/GaN high electron mobility transistor (HEMT) structure, with its two dimensional electron gas (2DEG) channel induced by piezoelectric and spontaneous polarization at the interface between the AlGaN and GaN layers, shows highly sensitive current changes to surface charges created by catalytic reaction of hydrogen gas on the Pt or Pd sensing layer.…”

Enhanced NO2 sensing characteristics of Pd-functionalized networked In2O3 nanowires

“…On the other hand, nanoscale materials in the form of nanowires, nanotubes, and nanoribbons have great potential for use as highly sensitive chemical sensors [26,27]. Their extremely high surface-to-volume ratios and single crystallinity in regard to onedimensional (1D) nanostructures may explain why the sensors are much more sensitive than those made from conventional materials.…”

Pt-decorated GaN nanowires with significant improvement in H 2 gas-sensing performance at room temperature

“…Likewise, H 2 sensors are needed for the safe take-off of rocket and in-flight safety systems [29,30,34].…”

“…Hydrogen is consumed in rocket fuel [24], which is the main gas evolving under pyrolysis at the initial stage of combustion [34,35]. Another important application of H 2 sensor is in fuel cells [2].…”