Metal-Oxide/GaN based NO2 Gas Detection at Room Temperature: An Experimental and Density Functional Theory Investigation

摘要

In this paper, standard top-down fabrication process has been employed to develop GaN nanowires and functionalize by three different metal oxides, such as- TiO_2, ZnO and SnO_2 for comparative analysis of NO_2 gas detection. The gas sensing results indicated that the HO_2 functionalized GaN exhibited the highest sensing performance toward our target gas at room temperature. The response-recovery process of these metal-oxide/GaN sensor devices has been analyzed here for various gas concentrations. The obtained experimental results were comprehensively explained by modeling with first-principles calculations based on density functional theory (DFT). All the modeling and calculations of metal-oxide/GaN structures in contact with NO2 molecule were performed in BURAI, a GUI of Quantum Espresso software. The adsorption properties and electronic structures (TDOS and PDOS) of these oxide functionalized GaN have been investigated to analyze the charge transfer process of actual sensor devices. In addition, the environmental humidity effect on the TiO_2/GaN device has been investigated experimentally and discussed under the light of DFT calculations.