Enhanced H2 Sensing Mechanisms of β-Ga2O3: Electrical Sensitivity and Surface Reactivity

Abstract

Detecting H2 can help prevent explosions caused by H2 leakage. β-Ga2O3 has attracted widespread attention for H2 detection because of its high-temperature stability, excellent H2 sensitivity and selectivity, and ease of device integration. However, the role of different crystal facets and source of the H2 activity in β-Ga2O3 in H2 sensing performance are still not completely understood. In this study, we investigated the role of the most common (−201)/(100)/(010) crystal facets of β-Ga2O3 in H2 sensing performance using density functional theory. The analyses of the adsorption process and density of states reveal that the intrinsic metallic characteristic of the (−201) crystal facet in β-Ga2O3 along with the formation of the thermodynamically favorable Gaδ+–Hδ− adsorption pair on the (−201) crystal facet contribute to its highest conductivity and H2 sensing capability. Furthermore, a (−201)C crystal facet was designed to facilitate the H2 desorption process by increasing the electrostatic force between Hδ+ and Hδ−, which is beneficial for the Ga2O3 sensor recovery. This study provides solid theoretical support to previous experimental and new mechanism insights regarding the H2 sensing electronic components of Ga2O3, paving the way for developing high-temperature H2 sensors for harsh environments.