Influence of Al/Si atomic ratio on optical and electrical properties of magnetron sputtered Al1-xSixOy coatings

Highlights: • The influence of Al/Si atomic ratio on properties of Al_1-xSi_xO_y coatings were studied. • The vol% of Al₂O₃ calculated from dielectric function and composition are different. • The variation of dielectric constant at 1 kHz depends on the vol% of Al₂O₃ phase. -- Abstract: This work presents a study on the influence of the Al/Si atomic ratio in dc magnetron sputtered Al_1-xSi_xO_y amorphous and transparent films upon their chemical composition, films' structure, optical and electrical properties. Increasing silicon in Al_1-xSi_xO_y films, from 0 at.% up to 31.1 at.%, caused an increment of deposition rate and an increment in Al-O-Si energy bonds as confirmed by X-Ray Photoelectron Spectroscopy (XPS) analysis. On other hand, the optical constants (refractive index (n) and extinction coefficient (k)), dielectric constant, loss tangent (tan δ) and ac conductivity (σ_ac) decrease when the amount of silicon in films increased. The results show that the refractive index shows small variations from linearity with vol% of Al₂O₃ (or SiO₂). Dielectric constant and dielectric loss evidenced two dipolar contributions, attributed to defects located one at or near the substrate/oxide interface, and the other in the bulk of the oxide.