An interesting Pd-AlGaN/GaN Schottky diode-type hydrogen sensor with ultrahigh sensing responses is fabricated and studied. A sensing response (SF) 2.04 × 105 and a widespread Schottky barrier height variation (ΔφB) of 400 meV are observed upon exposure to a 9660 ppm H2/air gas at 150 °C. The high sensing response can be attributed to the catalytic capability of Pd metal with contributions from a high-density 2-D electron gas induced from spontaneous and piezoelectric polarizations. From a Langmuir isotherm, the equilibrium constants are found to be 1.9 and 0.7 torr-1 at 150 °C and 200 °C, respectively. The fast response and recovery times (< 10 s) are found under a 9660 ppm H2/air gas. Consequently, the compatible process of the AlGaN/GaN sensor makes it possible to be integrated into other high-sensing performance sensor for microelectrical and mechanical applications.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering