Tailoring the refractive index of aluminum doped zinc oxide thin films by co-doping with titanium

► The Al-Ti co-doped zinc oxide (ATZO) thin films with different Ti doping concentration were deposited on glass substrates by radio frequency magnetron sputtering. ► The refractive index of aluminum doped zinc oxide was modulated through titanium co-doping. ► The refractive index of the thin films (at λ0 = 550 nm) increased from 1.91 to 2.05 as the TiO2 content increased from 0 wt% to 3 wt%. ► Tailoring the refractive index of aluminum doped zinc oxide thin films was important for applications in designing the integrated optoelectronic devices such as a-Si thin film solar cells.