Substrate-induced thermal residual stress and its influence on the structural, optical and electrical properties of n-CeO2 thin film junctions

CeO2 is one of a key functional material to deposit on different substrates for fabrication of solar cells, fuel cells, and other energy storage applications. The impact of substrate-induced stress on the performance of CeO2 thin films remains poorly understood. This study investigates the deposition of CeO2 on three different substrates p-type silicon (p-Si), fluorine-doped tin oxide (n-FTO), and neutral glass followed by Finite Element Analysis (FEA) for mapping residual stress. The charge carrier separation and recombination at the interfaces between CeO2 and these substrates were analyzed using X-ray diffraction (XRD), ultraviolet-visible (UV), and current-voltage (IV) characteristics. The films were prepared using sol-gel-derived CeO2 precursors and thermal evaporation, followed by microwave treatment to enhance interfacial charge separation and to suppress recombination. Substrate-dependent microstructural and electronic responses were probed; XRD analysis revealed micro-strain values ranging from 1.6 × 10−1 to 2.3 × 10−1 for CeO2/p-Si, with larger strain on CeO2/n-FTO, directly correlated with interfacial defect density and lattice distortion. Additionally, the resistivity of the CeO2/p-Si junction was 9.95 times lower than that of CeO2/n-FTO and 7.87 times lower than CeO2/neutral glass, demonstrating that interfacial charge transport is strongly governed by the underlying substrate. Finite element simulations revealed distinct residual stress profiles 2.67 × 102 MPa for neutral glass, 1.22 × 102 MPa for n-FTO, and 9.49 × 102 MPa for p-Si, correlating with experimental micro strain, conductive, and optical behavior. The results highlight the importance of charge carrier behavior at the substrate interfaces and suggest the potential of CeO2 based junctions for future energy-related applications.