Monday, October 5, 2015

Thin Films

A variety of methods are used to create thin film used across many industries. Thin film layers are measured in monolayers (a fraction of a nanometer) to micrometers of thickness. Semiconductors and optical coatings are the primary applications that benefit from thin film constructs.

The oldest method, known as Successive Ionic Layer Absorption-Reaction (SILAR), is needed to create thin film from various substrates to produce a variety of coatings for applications such as semiconductors and solar panels. Other thin film methods include thin film sputtering, sputtered coatings, hard/other sputtered coatings, evaporated coatings, and circuit fabrication.

SILAR Method

The SILAR method was first referred to in a scientific journal in 1985 (Indian Academy of Sciences). SILAR thin films production begins with immersion of film in a special chemical solution above the substrate. The film is immersed and removed from the chemicals multiple times. Finally, purified water is used to rinse the film once the proper coating of the film is achieved.

The SILAR method of coating thin film is advantageous because different materials can be applied to create film for any desired application. For example, temperature-sensitive substrates like polyester can be used.

The SILAR method is performed at room temperature, so damage does not result from extreme variations in temperature used in other thin film approaches. Semiconductors are especially sensitive to extreme temperatures and can be damaged when other thin film production methods are used.

Sputtered Thin Film

Sputtered thin film is made in a vacuum. The sputtering method uses metals. Positive ions are used to strike the metal at the atomic level. Resulting particles are gathered on clear polyester.

This basic film is used in a variety of applications, including window tinting. Sputtered film does not use pigments or dyes, so these materials do not separate. Metals used in the process do not oxidize. Drivers like sputtered film, because it is less reflective. A clearer view is safer and more comfortable.

Conductive Coatings

Conductive coatings are a type of sputtered coating. These coatings are used to coat alumina, diamond, aluminum nitride (AIN), polymers, silicon, and other substrates. The coating is typically applied in multiple layers. Conductive layers are frequently copper, silver, gold, palladium, or platinum. These conductive layers may include an undercoat layer (such as CR, TiW, NiCr, and Ti) and barrier layer (such as Mo, TiN, Ni, Pt, NiV, and others) to reduce diffusion that may occur at high temperatures.

Hard Coatings

The Hollow Cathode Magnetron Sputtering method employs substrate ion bombardment. This method is used to coat three-dimensional rotating parts or flat two-dimensional substrates.

Circuit Fabrication

Components are created according to design using either Au/Cu-based conductors as well as NiCR or TaN resistors if necessary. Circuits with front/back metallizations can be accomplished.

Conclusion

Technologies using thin film are helping solar manufacturers to lower the cost of solar cell production. Since thin film methods are cheaper to manufacture than early solar cell methods, more people can benefit from access to clean and sustainable energy.

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