Effects of post-thermal annealing on the performance characteristics of Pd/GaN Schottky diodes hydrogen sensors

The Pd/GaN Schottky diode was investigated as the hydrogen gas sensors. The post-thermal annealing was found to improve the Schottky characteristics significantly, i.e., the reverse leakage current was 5.9×10^-11 A at -5 V and the rectification ratio measured at ±1.0 V was 6.8 × 10⁸. The hydrogen sensing characteristics was also significantly improved after thermal annealing, i.e., the maximum sensitivity obtained under reverse bias condition was ~106, which was associated with the reduced Schottky barrier height.