Optical properties of gallium oxide thin films

The optical functions of β-Ga2O3 thin films have been determined by ellipsometry from 0.74–5 eV. Several electron-beam evaporated and rf magnetron sputtered films of different thicknesses were investigated using a multisample technique. Refractive index values comparable to those of bulk material are found. Cauchy dispersion model fits yield a high-frequency dielectric constant ε∞ of 3.57. Above 4.7 eV a direct absorption edge is observed.