ZnO-based antireflection layers obtained by the electron beam evaporation

In this work, research was carried out to analyze the possibility to fabricate nanostructured antireflection coatings based on ZnO. The dependence of structural features of the film on the substrate heating temperature during deposition of an aluminum-doped zinc oxide (AZO) has been studied. It is shown that it is impossible to obtain the required structural properties of the film by changing one parameter, the substrate temperature during deposition of the material, in the range of 20–600$^{\circ}$C. For this purpose, an approach has been suggested, which consists in preliminary deposition of a nanometer-thick Sn layer with subsequent substrate heating up to the temperature of deposition of the main material layer. The optimization of coating deposition conditions led to the fabrication of a medium consisting of many whiskers with transverse dimensions of tens of nanometers and a length of hundreds of nanometers, which are oriented mainly perpendicular to the substrate. It is shown that the gradient nature of a change in the material density, and, hence, in the effective refractive index in the direction perpendicular to the substrate plane, provides antireflection properties of the coating over a wide range of wavelengths as well as in different directions of light propagation.