Performance of Pt/Ga2O3/GaN Schottky-diode ammonia sensor covered with thermally evaporated Pt nanoparticles

Abstract

A Schottky-diode ammonia sensor utilizes a platinum (Pt)/Ga2O3/GaN structure coated with thermally evaporated Pt nanoparticles. Inserting a Ga2O3 sensing metal oxide with wide energy gap between the Pt catalytic metal and GaN layer can substantially reduce the metal-semiconductor Schottky barrier height upon detecting ammonia gas. Additionally, the thermally evaporated Pt nanoparticles on the Pt metal layer enhance surface roughness and the ratio of sensing surface area to volume, thereby improving ammonia adsorption efficiency. In experimental tests, the device achieves a high sensing response ratio (SR) of 733 at room temperature when exposed to 1000 ppm NH3/air while maintaining a forward voltage of 0.7 V. As the ammonia concentration decreases from 1000 ppm to 100 ppb NH3/air at 300 K, the SR decreases from 337 to 10.52 with a bias of 0.4 V. Due to its simple structure, ease of fabrication, excellent sensing performance, and durability at room temperature, this device stands as a strong candidate for application on ammonia sensing circuits.