Increasing the refractive index of materials via nanolamination: a-IGZO/TiO2 nanolaminates

We investigate nanolamination as a means of increasing the refractive index of materials, with a focus on [amorphous InGaZnO (a-IGZO)/TiO2](i) nanolaminates as composite transparent conducting oxides with a tunable index. We demonstrate that by periodic layering with TiO2 the refractive index of a-IGZO can be increased by up to Delta n approximate to 0.39 while the carrier mobility and conductivity retain 70% of their original values. This is shown to be a result of the alignment of the conduction bands of a-IGZO and TiO2. We also use optical modeling to verify the integral refractive index behavior of the nanolaminates and outline its range of applicability.