Optical and microstructural characterization of amorphous-like Al₂O₃, SnO₂ and TiO₂ thin layers deposited using a pulse gas injection magnetron sputtering technique

In this study, thin Al₂O₃, SnO₂ and TiO₂ films (37–58 nm) were deposited by means of a recently developed pulse gas injection magnetron sputtering method. The deposition rates are in the range from 1.7 nm/min (for Al₂O₃) to 24.4 nm/min (for SnO₂). Atomic force microscopy measurements show that the thus prepared layers are very smooth. The results obtained using scanning electron microscopy and Raman spectroscopy techniques revealed their amorphous-like nature. Optical properties of the dielectrics were examined by means of spectroscopic ellipsometry and show the red-shift of their band-gap energy and lower values of the refractive index compared to corresponding values determined for dense films and/or bulk materials. The microstructural and optical properties of examined oxides are directly associated with specific growth conditions (the impulse injection of the reactive gas) in the pulse gas injection magnetron sputtering process carried out in the low pressure oxygen plasma. - Highlights: • Dielectric films were deposited by means of the GIMS process. • Dielectric films are exceptionally smooth. • The refractive index of the oxide layers is relatively low. • Band-gap energy values are slightly lower than those presented in other studies.