Hydrogen-Sensing Characteristics of a Pd/GaN Schottky Diode With a Simple Surface Roughness Approach

Hydrogen-sensing characteristics of a Pd/GaN Schottky diode with a simple surface roughness approach are studied and demonstrated. A high sensing response Sr of 2.05 × 10⁵ and a large Schottky barrier height variation ratio (ΔφB/φ_air) of 36.3% upon exposure to a 1% H₂/air gas at 303 K are found. They could be attributed to the presence of more adsorption sites caused by the employed surface plasma treatment. The increase in series resistance due to the decrease in sensing response under the applied voltage range from 0.5 to 1 V is found. Based on the kinetic analysis and transient-state behavior measurement, at 523 K, the studied device shows a faster adsorption time of 2.9 s and a higher initial rate of 968 μA/s. Consequently, the studied structure provides a promise for high-performance GaN-based Schottky-diode-type hydrogen sensor applications.