Carbon Ion Implantation Effects on Morphology, Bandgap, and Urbach Tailing in ZnO Thin Films

K. Suchaneka, K. Wojtasika, O. Lośa, M. Mitura-Nowakb, S. Kącc aCracow University of Technology, Faculty of Materials Engineering and Physics, Department of Physics, Podchorążych 1, 30-084 Kraków, Poland bInstitute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków, Poland cAGH University of Science and Technology, Department of Surface Engineering and Materials Characterisation, Faculty of Metals Engineering and Industrial Computer Science, al. A. Mickiewicza 30, 30-059 Kraków, Poland

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Zinc oxide (ZnO) is a wide-bandgap semiconductor with diverse applications in optoelectronics and sensing. In this study, we examine how 20 keV C+ ion implantation affects the morphology and optical properties of ZnO thin films. Using atomic force microscopy and ultraviolet-visible spectroscopy, we observe that ion implantation leads to a reduction in grain size, increased morphological disorder, and a fluence-dependent increase in both the optical bandgap and Urbach energy. Simulations using the Transport of Ions in Matter code indicate that implanted ions penetrate the ZnO layer to an average depth of around 41 nm, generating near-surface structural damage. Post-implantation annealing at 500° partially restores the optical properties, indicating some level of defect recovery. These findings demonstrate that low-energy carbon ion implantation enables controlled tuning of the properties of ZnO thin film without structural degradation.

DOI:10.12693/APhysPolA.148.89 topics: ion irradiation, zinc oxide, thin films, ultraviolet-visible (UV-Vis) spectroscopy