Layer by layer
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This article may require cleanup to meet Wikipedia's quality standards. Please improve this article if you can. (January 2008) |
Layer-by-Layer (LbL)deposition is a thin film fabrication technique. The films are formed by depositing alternating layers of oppositely charged materials with wash steps in between. A simple representation can be made by defining two oppositely charged polyions as + and -, and defining the wash step as W. To make an LbL film with 5 bilayers one would deposit W+W-W+W-W+W-W+W-W+W-W, which would lead to a film with 5 bilayers, specifically +-+-+-+-+-. The bilayers and wash steps can be performed in many different ways including dip coating, spin-coating, spray-coating and flow based techniques.
LbL offers several advantages over other thin film deposition methods. LbL is extremely simple and cheap. There are a wide variety of materials that can be deposited by LbL; there are many polyions, metals, ceramics, nanoparticles and biological molecules. Another important quality of LbL is the high degree of control over thickness, which comes about due to the linear growth of the films with the number of bi-layers. By the fact that each bilayer can be as thin as 1 nm, this method offers easy control over the thickness with 1 nm resolution.
LbL has found applications in rust control, biomedical applications and much more.
