A classification of thin film configurations

Concerning the degree of constraint on deformation, a small structure is said to be unconfined if the boundaries associated with its thin dimensions are free to displace without restriction. On the other hand, it is said to be fully confined if all boundaries associated with its thin dimensions are constrained against deformation. In virtually all cases, the constraint at a boundary is due to another material which shares that boundary as a com- 

The idea of the classification scheme is intended only as a conceptual guide. There are many situations in which the structure exhibits behavior represented by more than one entry in the categorization matrix in Fig- 

When the small dimension of the material structure is comparable to the characteristic microstructural size scale, the film is considered to be a micro structurally thin film. Most metallic thin films used in microelectronic devices and magnetic storage media are examples of microstructurally thin films, where the film thickness is substantially greater than atomic or molecular dimensions. Although the film thickness normally includes only a few 

Atomically thin films constitute layers whose thicknesses are comparable to one or a few atomic layers. An adsorbed monolayer of gas or impurity atoms on a surface is an example of an atomically thin layer. Here the mechanical response of the thin layer is likely to be more influenced by interatomic potentials and surface energy than by macroscopic mechanical properties or by micromechanisms of deformation. 

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