'Thin films & coatings' Roadmap - Nano Mahidol

Optical properties
These include a.o. light emission, trapping, transmission, opaqueness, fluorescence,
waveguides, anti reflection, etc. Some thin films have the ability to emit light without
the need for a backlight; these are applied in displays. Thin films can be designed to
be transparent or opaque (or both depending on the applied voltage or incident light)
and applied, a.o. in windows, displays or solar cells. In some cases multi-layered thin
films are required for achieving the desired properties (e.g. OLEDs use small
molecules in multi-layers for up to full colour displays). Thin films of high refractive
materials could be designed to be planar waveguides for photonics’ applications.
Dielectric thin films could also be used to generate surface plasmons resonance
that’s exploitable in optical modulators or chemical sensors. Nanotechnology enables
a precise knowledge on the exact thickness required for desired optical and/or
electrical properties. The interface between the thin film/layer and the substrate is
crucial for understanding the optical (but also) electrical behaviour at ever decreasing
thicknesses and for optimising the layer thickness.
Mechanical properties
These include a.o. wear/ abrasion resistance, hardness, scratch resistance, dry
lubrication, reduced Strain-to-failure, etc. Surface heterogeneities of either chemical
or morphological origin drastically affect interface phenomena (wetting-adhesionfriction).
Nanotechnology enables the design and production of thin films with the
required thickness and topography.
Electrical (conductivity, insulation, etc.) and magnetic properties:
Highly dependent on the chemical composition, some thin films’ high conductivity
properties are of great importance for CMOS’ wiring materials or for OLEDs. The
dielectric characteristic of some thin films’ material is exploited together with
magnetic properties in high-density storage and non-volatile memory applications.
Nanotechnology in this area enables the preparation of thinner films as well as a
better dispersion of magnetic particles.
Thermal properties
Thin film coatings are applied in windows or more sophisticated applications like
aircraft engines (e.g. Thermal Barrier Coatings based on Zirconia). Nanotechnology
enables the optimisation of thin film thickness and density (incl. pores, if any) to
specific requirements. Application of multi-layered thin films allows, for instance,
blocking the travel of atomic vibrations that produces heat flow whilst still letting the
electrons flow as a current (application in thermoelectric devices).
9 Roadmap report on
Thin films and coatings