Term: thin film
https://doi.org/10.1351/goldbook.T06345

Definition:
A film whose thickness is of the order of a characteristic scale or smaller. Since a film may 'look' operationally thin or thick, according to the procedure applied, it is also recommended that the measurement procedure employed be specified (e.g. ellipsometrically thin film, optically thin film, etc.). It is recommended that the physical specification of the film thickness be used, whenever possible (e.g. thick compared to the electron mean free path, thin compared to the optical wavelength, etc.)

Related Terms:
1) film (<em>in thin films</em>) (http://doi.org/10.1351/goldbook.F02366).
2) characteristic scale (<em>in thin films</em>) (http://doi.org/10.1351/goldbook.C00977).
3) mean free path (<em>in thin films</em>) (http://doi.org/10.1351/goldbook.M03778).
4) wavelength (<em>in thin films</em>) (http://doi.org/10.1351/goldbook.W06659).

Source: PAC, 1994, 66, 1667. 'Thin films including layers: terminology in relation to their preparation and characterization (IUPAC Recommendations 1994)' on page 1672 (https://doi.org/10.1351/pac199466081667)

Citation: 'thin film' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.T06345

License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms.

Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.