Optical characterization of the annealing effect on Ge5Te20Se75 thin films by variable angle of-incidence spectroscopic ellipsometry

摘要: Abstract Ternary Ge 5 Te 20 Se 75 thin films deposited by thermal evaporation were annealed at different temperatures below the crystallization temperature for 15 min under vacuum. The annealing effect on optical properties of was studied means variable angle spectroscopic ellipsometry (VASE) in spectral range from 245 to 1700 nm. measured VASE spectra examined using individual Tauc–Lorentz (TL) and Cody–Lorentz (CL) dispersion models, linear combinations TL or CL model with multiple Gaussian functions ( G ). It is demonstrated that models are not appropriate characterization films. Moreover, it shown both CL + 3G TL + 3G satisfactory ones these found energy gap E g ) obtained Tauc method decreases 1.2 0.86 eV increasing room 150 °C. This result can be interpreted chemical bond arrangement approach. On other hand, maximum value refractive index n shifted toward long wavelength temperature.