Phi versaprobe 2

The crystal structure of N-TiO₂ was studied by powder X-ray diffraction (XRD) (PANalytical Model X’Pert PRO diffractometer, PANalytical, Almelo, The Netherlands) with Cu Kα radiation (λ = 1.54 Å) by scanning at a rate of 2° (2θ) min⁻¹. X-ray photoelectron spectroscopy (XPS) was utilized to study the nitrogen doping of N-TiO₂. XPS was conducted by a Phi Versaprobe II, Ulvac-PHI, Kanagawa, Japan utilizing monochromatic source Mg Ka.

The thickness and refractive index (R.I.) of AlN thin films were measured by spectroscopic ellipsometry (SE, M-2000DI, J.A. Woolam, Lincoln, NE, USA) and the values were fit using the spectra measured at 3 different angles (55°, 65°, and 75°). The chemical composition and bonding states of AlN thin films were characterized by X-ray photoelectron spectroscopy (XPS). XPS analysis was performed using a PHI VersaProbe II (ULVAC-PHI, Chigasaki, Kanagawa, Japan) equipped with a monochromatic Al Kα X-ray source (E_Photon = 1486.6 eV). To remove surface contaminants, Ar gas cluster ion beam (GCIB) sputtering with a beam energy of 1 kV and the cluster size of 2500 atoms was employed. The elemental composition of the films was calculated based on the peak area and atomic sensitivity factor [23 ]. Surface roughness of AlN films was determined by atomic force microscope (AFM) (Veeco Multimode V. Non-contact AFM, Veeco, Plainview, NY, USA).

The chemical surface compositions were analyzed by high-resolution X-ray photoelectron spectroscopy (XPS) using a PHI VersaProbe II (Ulvac-phi, Inc., Chigasaki, Japan) with a monochromatic Al-Kα source, and photon energy of 1486.6 eV. The X-ray source used had a power of 100 W, whereby the sample surface was scanned with a beam size of 100 µm over an area of 1400 × 200 µm². High-resolution spectra of the coated and uncoated samples (n = 6) were recorded with a pass energy of 46.95 eV and a step size of 0.1 eV, with a constant electron take off angle of 45°. The spectrometer was calibrated to the copper and gold reference lines (932.62 eV and 83.96 eV), whereas the minimum detector resolution measured at the silver peak Ag (3d5/2) was 0.6 eV, with a pass energy of 23.5 eV. The measurements were obtained at room temperature and a base pressure of 2 × 10⁻⁶ Pa. To avoid charging effects, all measurements were carried out with charge compensation by utilizing a cold cathode electron flood source and low-energy argon ions. All spectra were shifted to the carbon peak (C1s) to 284.6 eV. The data analyses were performed using the software MultiPak (version 9.9.0.8, Ulvac-phi, Inc., Chigasaki, Japan).