Growth and microstructural study of In2O3 single-crystalline thin films via low-pressure chemical vapor deposition

Abstract

Epitaxial In2O3 thin films with well-defined (111), (100), and (110) crystallographic orientations were successfully grown on yttria-stabilized zirconia substrates via low-pressure chemical vapor deposition. Heteroepitaxial alignment of In2O3 films with a body-centered cubic structure was confirmed by x-ray diffraction Φ-scan analysis. Comprehensive characterizations included optical absorption spectroscopy, photoluminescence, surface morphological analysis using scanning electron microscopy, atomic force microscopy, and ambient-temperature scanning tunneling microscopy. Optical measurements reveal strong ultraviolet absorption peaks, consistent with the expected wide bandgap semiconductor nature of In2O3. Orientation-dependent surface morphologies were observed: (111) films exhibit striped patterns with dislocation networks, (100) surfaces feature pyramidal terraces, and (110) films show stripe-like structures aligned along specific crystallographic axes. Significantly, ultrahigh vacuum scanning tunneling microscopy enabled atomic-resolution imaging of sputter-annealed In2O3 (111) surfaces, revealing localized atomic ordering despite the presence of pervasive defects like vacancies and lattice distortions.