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

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.

Automated summary

Thin films of scandium oxide (Sc2O3) were deposited on silicon substrates to study the effect of thickness on work function reduction. Various measurements, including X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), energy dispersive X-ray reflectivity (EDXR), atomic force microscopy (AFM), and ultraviolet photoelectron spectroscopy (UPS), were performed on the films of different nominal thicknesses (ranging from 2-50 nm) and in multi-layered mixed structures with barium fluoride (BaF2) films. The results showed that non-continuous films were necessary to minimize the work function, even with a stoichiometry far from ideal (Sc/O = 0.38), due to the formation of surface dipole effects between crystalline islands and substrates. Furthermore, the presence of BaF2 in multi-layered films did not contribute to further work function reduction.