Fig. 1. Fitting results of Ψ and Δ for fresh Ge_27.4Ga_7.3S_65.3 film by the Cauchy model. Two test angles (65° and 75°) are employed here.

Fig. 2. Linear refractive index at 1550 nm wavelength for the as-deposited films as a function of MCN.

Fig. 3. The relationship between refractive index variation of Ge–Ga–S film and annealing time.

Fig. 4. Optical band-gap energy for as-deposited films as a function of MCN.

Fig. 5. Relationship between optical band-gap variation and annealing time of Ge–Ga–S films.

Fig. 6. Film thickness variation as a function of annealing time.