Optical properties of metal (Al, Ag, Sb, and Sn)-ion-implanted ZnO films have been studied by ultraviolet-visible spectroscopy and spectroscopic ellipsometric techniques. The effects of metal-ion doping on the optical band gap $\left(E_g\right)$ , refractive index $\left(n\right)$ , and extinction coefficient $\left(k\right)$ of nanocrystalline ZnO films have been studied for the similar implantation dose of all the metal ions. The ellipsometric spectra of the ion-implanted samples could be well described by considering an air/roughness/$\mathrm{Zn}\mathrm{O}–M$ (layer 1)/ZnO (layer 2)/glass model. The band gap of ZnO films increases with Al ion doping and decreases with doping of Ag, Sb, and Sn ions. The refractive index of ZnO films in the visible spectral region increases substantially on Sb and Sn ion doping, while it decreases to some extent with Al ion doping.

The optical transmittance of Ge:Sb:Te evaporated thin film alloys with different compositions was measured in the wavelength range from 2.5 to 34 $\mu$ m. The as-deposited films with an amorphous structure were thermally crystallized to achieve the two known crystalline phases: the fcc and the hexagonal at higher treatment temperatures. There are drastic changes in the transmittance spectra of samples with different structural phase, which reflects the differences in their optical constants. For amorphous films, only the frequency independent term in Drude’s formula is required to properly describe their transmittance spectra. For samples in the hexagonal and the fcc structures, the transmittance spectra show a metallic and semimetallic behavior, respectively; therefore, the full Drude expression has been used as the general dispersion relation for the optical constants of the films. The electrical conductivity deduced from the Drude expression shows a dependence on Sb concentration in good agreement with previously reported values measured on bulk single crystals. Furthermore, the n and k spectra obtained in the measured infrared range are in good agreement with the values in the visible-UV region, previously measured using spectroscopic ellipsometry.