Fabrication and Microstructural Analysis of ZnO and In2O3 MOS Thin Film Sensors with Embedded Microheaters for Methane Sensing
Year: 2026
Type: preprint
Abstract: Methane detection is essential for both environmental monitoring and industrial safety due to its greenhouse impact and explosive potential. Conventional sensing approaches, such as electrochemical, infrared, and catalytic bead sensors, are limited by stability and sensitivity constraints. Metal oxide semiconductor (MOS) sensors, particularly those based on ZnO and In2O3, provide an attractive alternative owing to their stability, high sensitivity, compactness, and fabrication compatibility. In this work, compact MOS chip sensors were developed using a six-layer architecture that integrates a microheater for localized thermal control. Thin films of ZnO and In2O3 were deposited via magnetron sputtering with photolithographically defined geometries, followed by annealing under inert gas conditions. Microstructural and surface morphological characterization was performed using atomic force microscopy (AFM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Results revealed that ZnO films undergo significant surface restructuring upon annealing, exhibiting increased roughness, grain coarsening, and oxygen vacancy formation, whereas In2O3 retained compact morphology and stoichiometric stability. These findings establish a sensitivity–stability trade-off between the two materials, with ZnO showing higher surface activity favourable for methane adsorption, and In2O3 offering reproducibility and long-term stability.
Source: ChemRxiv
Authors: D.Lalitha Manaswini, Aroba Saleem
Institution: University of Florida
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7223111006