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

Alessio Mezzi; Eleonora Bolli; Saulius Kaciulis; Alessandro Bellucci; Barbara Paci; Amanda Generosi; Matteo Mastellone; Valerio Serpente; Daniele Maria Trucchi

doi:10.3390/nano13081430

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

Nanomaterials (Basel). 2023 Apr 21;13(8):1430. doi: 10.3390/nano13081430.

Authors

Alessio Mezzi¹, Eleonora Bolli², Saulius Kaciulis¹, Alessandro Bellucci², Barbara Paci³, Amanda Generosi³, Matteo Mastellone², Valerio Serpente², Daniele Maria Trucchi²

Affiliations

¹ Institute for the Study of Nanostructured Materials, ISMN-CNR, Montelibretti, 00010 Rome, Italy.
² Institute of Structure of Matter, DiaTHEMA Lab, ISM-CNR, Montelibretti, 00010 Rome, Italy.
³ Institute of Structure of Matter, ISM-CNR, 00133 Rome, Italy.

Abstract

Thin films based on scandium oxide (Sc₂O₃) were deposited on silicon substrates to investigate the thickness effect on the reduction of work function. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), energy dispersive X-ray reflectivity (EDXR), atomic force microscopy (AFM), and ultraviolet photoelectron spectroscopy (UPS) measurements were performed on the films deposited by electron-beam evaporation with different nominal thicknesses (in the range of 2-50 nm) and in multi-layered mixed structures with barium fluoride (BaF₂) films. The obtained results indicate that non-continuous films are required to minimize the work function (down to 2.7 eV at room temperature), thanks to the formation of surface dipole effects between crystalline islands and substrates, even if the stoichiometry is far from the ideal one (Sc/O = 0.38). Finally, the presence of BaF₂ in multi-layered films is not beneficial for a further reduction in the work function.

Keywords: AFM; EDXR; UPS; XPS; XRD; electron-beam evaporation; scandium oxide; work function.

Grants and funding

737054/European Commission