Interfacial-reaction-driven carbon removal and phase evolution in ALD-grown SrO thin films

초록

Strontium oxide (SrO) deposited by atomic layer deposition (ALD) serves as a key building block for the fabrication of Sr-based compound oxides for next-generation electronic devices. In this work, nanoscale SrO thin films were systematically investigated in terms of their chemical composition, crystallinity, and post-deposition annealing behavior. X-ray photoelectron spectroscopy (XPS) depth profiling revealed the presence of carbon throughout the films, indicating the formation of SrCO3 originating from residual precursor ligands. Notably, the carbon concentration exhibited substrate-dependent behavior at the interface region. Upon annealing, a significant reduction in carbon concentration was observed, accompanied by the crystallization of SrO and the formation of substrate-dependent Sr-based compounds, as confirmed by X-ray diffraction (XRD). Combined interfacial chemical analysis and thermodynamic considerations reveal that the removal of SrCO3 is primarily governed by reactions with interfacial oxides rather than simple thermal decomposition. These findings provide a systematic understanding of the growth behavior and thermal evolution of ALD SrO thin films, offering practical guidelines for controlling interfacial chemistry in the fabrication of Sr-based compound oxides for advanced electronic applications.

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