Multi-Technique Approach for Work Function Exploration of Sc₂O₃ Thin Films.

Area of Science:

• Materials Science
• Surface Science
• Nanotechnology

Background:

• Work function reduction is crucial for advanced electronic devices.
• Scandium oxide (Sc₂O₃) is a promising material for modifying surface properties.
• Understanding film morphology's impact on work function is essential.

Purpose of the Study:

• To investigate the effect of scandium oxide (Sc₂O₃) thin film thickness on work function reduction.
• To explore the role of film continuity and stoichiometry in work function modification.
• To assess the influence of barium fluoride (BaF₂) in multi-layered structures.

Main Methods:

• Deposition of Sc₂O₃ thin films with varying thicknesses (2-50 nm) using electron-beam evaporation.
• Fabrication of multi-layered Sc₂O₃/BaF₂ films.
• Characterization using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), energy dispersive X-ray reflectivity (EDXR), atomic force microscopy (AFM), and ultraviolet photoelectron spectroscopy (UPS).

Main Results:

• Non-continuous Sc₂O₃ films minimize work function, reaching as low as 2.7 eV at room temperature.
• Surface dipole effects between crystalline islands and silicon substrates are responsible for work function reduction.
• Stoichiometry (Sc/O = 0.38) deviates from ideal, yet effective work function reduction is achieved.
• Incorporation of BaF₂ in multi-layered films did not enhance work function reduction.

Conclusions:

• Optimizing thin film morphology, specifically achieving non-continuous structures, is critical for effective work function reduction.
• Surface dipole formation is the primary mechanism for work function lowering in these Sc₂O₃ films.
• Barium fluoride is not beneficial for further work function reduction in Sc₂O₃-based multi-layered systems.