Thermally robust optical properties of the wafer-scale α-Sb₂O₃ films

As a molecular crystal, the wafer-scale Sb₂O₃ films were deposited successfully by standard thermal evaporation deposition and their optical behaviours have been investigated in detail. XRD reveals that the as-deposited Sb₂O₃ films have a cubic phase (α-Sb₂O₃) with a lattice constant of about 11.16 Å. In a further step, the thermal stability of lattice vibrations and optical constants of the as-deposited α-Sb₂O₃ films have been investigated by Raman and ellipsometric spectra at various temperatures from 200 to 600 K. The temperature-dependent frequencies, intensities, and widths of the first-order Raman-active modes have a linear trend without phase transitions in the temperature range, which is confirmed by the temperature-dependence of optical constants (ϵ_r and ϵ_i) and optical band gap (E_g = 4.3∼ 4.4 eV) extracted from the ellipsometric spectra. In addition, theoretical calculations were performed to clarify the physical mechanisms of dielectric constants and electronic transitions. The thermally robust crystalline structure and optical properties are very helpful for the α-Sb₂O₃ based (opto)electronic devices.