Anisotropic coatings

Anisotropic coatings

Anisotropic coatings based on nano / micro pillars

In the process of electron-beam sputtering, the target is irradiated with a high-energy electron beam b the atomic gas phase is formed. These atoms are then deposited onto the desired substrates. Colloidal monolayers can be used as a substrate. In the case of such substrates, the deposited atoms remain on colloidal micro / nanospheres, forming columnar structures, Fig. 1. Various compounds can produce columnar structures, including semiconductor and dielectric materials.

Fig. 1. Nanocolumns formed by vacuum deposition of silicon dioxide (left) and ITO (right) onto a substrate consisting of a 200 nm colloid monolayer.
Atoms, falling on a spherical particle, are forced to settle in the direction of the flow of matter. In a normal (perpendicular to the substrate surface) flow of matter, the columnar structures are perpendicular to the substrate. With beams tilted relative to the substrate, the tilt angle of such structures changes (Fig. 2, left). The method is known and called Glancing Angle Deposition (GLAD).

 

Fig. 2: Deposition of a SiO2 layer at an angle of 45 degrees relative to the substrate (left) and deposition of a multilayer antireflection structure SiO2 / Nb2O5 (right)
The so-called GLAD is a material deposition process in which there is a large angle of incidence between the deposition flow and the normal to the surface. GLAD can form tilted columnar structured arrays, with the shape of the columns controlled by rotating the matte.
It is also possible to grow columnar structures from alternating materials, for example, to form antireflection (Fig. 2b on the right). Two materials with different refractive indices are clearly distinguishable. The image also shows the places of stabilization of the columnar structures, which is quite important for legal applications. Such structures can be used as superhydrophilic surfaces, catalysts, optical elements, such as, for example, waveguides, etc. Izovac Group of Companies can offer both equipment for applying a template on substrates of significant sizes, and installations for subsequent spraying.