Effect of thermal annealing on the optical stability of GeTe-doped Sb2Se3 thin films

•GeTe-doped Sb2Se3 thin films have been deposited by magnetron sputtering method.•Films with high refractive index and good stability in the infrared window belong to the 15.7 at.% GeTe doped Sb2Se3 films.•(Sb2Se3)84.3(GeTe)15.7 may be a potential material for photonic device applications. Sb2Se3 thin films have high nonlinear refractive index and high infrared transmittance, but its optical stability is slightly poor. In this work, GeTe-doped Sb2Se3 thin films have been deposited by magnetron sputtering method and studied the optical and thermal properties of the films. The crystallization temperature of thin films gradually increased with the doping of GeTe (less than 15.7 at.%), from 208 ℃ to 284 ℃, and then decreases to 270 ℃ with increasing GeTe from 15.7 to 23.7 at.%. These films were subjected to heat treatment, after annealing for 30 h, the band gap and refractive index of films exhibit the smallest change ratio in terms when the GeTe content was 15.7 at.%. Based on optical band gap and refractive index, (Sb2Se3)84.3(GeTe)15.7 thin film with stable optical and thermal properties was selected for application in optical waveguide devices.