Enkellags

Enkellags is a term used in materials science and surface engineering to denote a coating or film that consists of a single molecular layer in thickness. The designation is particularly common in Swedish-language literature and is often used interchangeably with monolayer or single-layer coatings.

Typical thicknesses for enkellags are on the order of 0.2 to 2 nanometers, depending on the film-forming molecules and the deposition method. The film is usually highly uniform and continuous, but pinholes and defects can occur, especially on imperfect substrates. Because it is only one molecule thick, enkellags provide precise control over surface properties and can serve as functional interfaces.

Formation methods include self-assembled monolayers (SAMs) on reactive metal or oxide surfaces, Langmuir-Blodgett deposition to transfer preassembled monolayers, and specialized deposition techniques tuned for monolayer thickness control, such as adaptations of atomic layer deposition. The choice of molecule dictates surface chemistry, wettability, and electrical or optical behavior.

Properties and limitations of enkellags include exceptional surface conformity and tunable functionality, enabling roles as barrier layers, chemical passivation, or interface modifiers. Their mechanical robustness is typically limited compared with thicker films, and performance can be dominated by defects or environmental sensitivity.

Applications span corrosion protection, microelectronics passivation, biosensing, and surface functionalization for biocompatible or selective interfaces. Common examples include alkanethiol SAMs on gold and organosilane monolayers on silicon oxide. Enkellags sit between bare surfaces and multilayer coatings, offering thin, controllable surface modification with trade-offs in durability and defect tolerance.

See also: monolayer, thin film, self-assembled monolayer, Langmuir-Blodgett film.