Optical and Electrical Properties of Cerium Oxide Thin Films

Cerium oxide (CeO₂) thin films exhibit a combination of wide-band-gap semiconducting behaviour, high refractive index and prominent ionic conduction arising from the Ce³⁺/Ce⁴⁺ redox couple. Typically deposited by techniques such as atomic layer deposition, sol–gel, sputtering and spray pyrolysis, these films crystallise in a fluorite lattice that confers robust thermal and chemical stability. Optically, undoped films display a band gap of 3.2–3.6 eV, high transparency in the visible region and an extinction coefficient that can be tuned via vacancy concentration or rare-earth doping. Oxygen vacancies introduce sub-band absorption features and modify the Raman-active F₂g mode, allowing direct monitoring of local defect populations. Electrically, CeO₂ films function as high-κ dielectrics, exhibit moderate electronic conductivity and support fast oxygen-ion mobility, making them attractive for memristive devices, gas sensors and protective passivation layers in metal-oxide-semiconductor structures. The interplay between microstructure, vacancy density and interface chemistry governs both optical loss and leakage currents, underpinning applications in photovoltaics, smart coatings and transparent electronics.

Research from Nature Portfolio

Recent studies have demonstrated precise control of crystallite orientation and surface facets in glass-supported ceria films using ultrasonic spray pyrolysis. By adjusting precursor flow, solution concentration and substrate temperature, researchers achieved preferential texture along the (100) and (111) directions or fully random orientation. This texturing alters the relative exposure of thermodynamically stable facets, modulating optical absorption edges, Raman responses and film morphology. Films with (111)-dominant texture show sharper optical transitions and reduced light scattering, while mixed-facet coatings offer enhanced defect-related absorption useful for photocatalysis and UV filtering. Such scalable, low-cost deposition highlights the importance of facet engineering for tailoring optical and electrical responses in large-area applications.

Optical and Electrical Properties of Cerium Oxide Thin Films publication trend

The graph below shows the total number of articles in optical and electrical properties of cerium oxide thin films across all publications each year (not limited to Nature Index journals).

Technical terms

Optical band gap: Energy difference between valence and conduction bands dictating absorption edge.

Dielectric constant (κ): Measure of a material’s ability to polarise in response to an electric field.

Fluorite structure: Cubic oxide lattice in which each metal ion is coordinated by eight oxygen ions.

Oxygen vacancy: Missing oxygen atom in the lattice that creates defect states and influences conductivity and absorption.

Atomic layer deposition (ALD): Sequential, self-limiting chemical vapour technique for uniform thin-film growth.

Sol–gel method: Wet-chemical process converting molecular precursors into oxide networks via hydrolysis and condensation.

References

1. Effects of Varying Annealing Ambient towards Performance of Ternary GaxCeyOz Passivation Layers for Metal‐Oxide‐Semiconductor Capacitor. International Journal of Energy Research (2024).
2. Raman Study of Nanocrystalline-Doped Ceria Oxide Thin Films. Coatings (2020).
3. Strong texture tuning along different crystalline directions in glass-supported CeO2 thin films by ultrasonic spray pyrolysis. Scientific Reports (2021).
4. Influence of Post-Annealing Treatment on Some Physical Properties of Cerium Oxide Thin Films Prepared by the Sol–Gel Method. Crystals (2024).