Pt-AlGaN/GaN HEMT-based hydrogen gas sensors with and without SiNx post-passivation

Abstract

GaN-based sensors have been widely investigated thanks to its potential in detecting the presence of hydrogen. In this study, we fabricated hydrogen gas sensors with AlGaN/GaN heterojunction and investigated how thesensing performance to be affected by SiN surface passivation. The gas sensor employed a high electron mobilitytransistors (HEMTs) with 30 nm platinum catalyst as a gate to detect the hydrogen presence. SiN layer wasdeposited by inductively-coupled chemical vapor deposition as post-passivation. The sensors with SiN passivationexhibited hydrogen sensing characteristics with various gas flow rates and concentrations of hydrogen in inertbackground gas at 200 oC similar to the ones without passivation. Aside from quick response time for bothsensors, there are differences in sensitivity and recovery time because of the existence of the passivation layer. The results also confirmed the dependence of sensing performance on gas flow rate and gas concentration.