Comparative Optical Properties of Amorphous and Crystalline MoO₃ Films by Spectroscopic Ellipsometry Study

This paper presents a comprehensive study of the optical properties of amorphous and crystalline MoO 3 thin films using spectroscopic ellipsometry. MoO 3 films were deposited on SiO 2 /Si substrates with varying oxide thicknesses using the atomic layer deposition (ALD) method. The study utilized various optical oscillator models, including Lorentz, Tauc–Lorentz and Harmonic, to analyze the dielectric functions and identify midgap states resulting from oxygen deficiencies. The findings highlight significant differences in the optical properties between amorphous and crystalline MoO 3 films, demonstrating the impact of structural phases and substrate conditions. Specifically, amorphous films exhibited lower broadening and energy peaks compared to crystalline films, which showed distinct midgap states indicative of higher oxygen vacancy concentrations. These results enhance the understanding of the optical behavior of MoO 3 films and their potential applications in advanced optoelectronic devices.