comment on this article

Plasma patterning technique can form new optical metasurfaces

Researchers from the University of Southampton have demonstrated a new patterning technology that makes it possible to create high-quality nanostructured surfaces for infrared thermal control coatings and nonlinear optics.

Metasurfaces are man-made structures that are designed to control light and other forms of radiation using very small elements, typically with sub-micrometer dimensions.

Conventional methods of producing theses advanced material coatings typically require specialist cleanroom facilities capable of etching patterns into materials or deposit separated structures on the surface by a process called lift-off lithography. The resulting surface topography, however, is not always suitable and can strongly limit the device performance when embedded into a stack of many independent layers.

The researchers explored a new technology that locally and selectively modulates optical properties without changing the flatness of the material surface. The research was based on new technique and the discovery that an oxygen plasma can greatly reduce the electron concentration of certain metal oxides, which hold unique properties for integrated circuits, solar cells, chemical sensing and catalysis.

The plasma patterning technique has been demonstrated by fabricating two devices, a planar metasurface-based optical solar reflector for satellite radiant cooling and a multiband metasurface with different operation ranges.

The research involved close collaboration between Southampton University and physicists and Sustainable Electronic Technologies experts in Electronics and Computer Science (ECS). The Southampton team, led by Physics and Astronomy’s Professor Otto Muskens and ECS’s Professor Kees De Groot, have published the research in Advanced Materials.

According to Dr Kai Sun, lead author, “Plasma patterning provides a completely new route to form electrical and optical devices with structures beyond existing manufacturing limitations. Here, we have shown for the first time that a planar metasurface, based on aluminum-doped zinc oxide, can be achieved with an optical metasurface function but physically flat.

“The metasurface devices in this work are only a start of this new technique’s applications and its full potential impact is still to be seen.”

Transparent conductive oxides such as aluminium-doped zinc oxide (Al:ZnO) have a high electron density, making it dielectric in visible range but metallic in infrared (IR) range. This electron density of Al:ZnO is critical for its material electrical and optical properties. To achieve an optical property contrast, which is required for optical metasurface formations, parts of the Al:ZnO film need to be removed, leaving a non-planar structure.

The study found that oxygen plasma can reduce Al:ZnO electron density by up to five orders of magnitude. This led the team to propose the new fabrication technique that forms a metasurface by selectively modulating the electron density using oxygen plasma, made possible by accurate location control through a lithography definition.

The fabricated device achieves its metasurface function for its optical property contrast but maintains a planar topological surface profile. This metasurface is highly desirable for its compatibility with any added functional layers.

Southampton scientists have applied to file the plasma patterning technique as a UK patent. Research was funded by the Dstl MultiMeta project, which has currently entered its second phase of development.

Neil Tyler

Comment on this article

This material is protected by MA Business copyright See Terms and Conditions. One-off usage is permitted but bulk copying is not. For multiple copies contact the sales team.

What you think about this article:

Add your comments


Your comments/feedback may be edited prior to publishing. Not all entries will be published.
Please view our Terms and Conditions before leaving a comment.

Related Articles

Automotive displays

​Smartphones, tablets, televisions: touch displays are ubiquitous and are ...

CES 2021

The first ever all-digital CES took place last month and below we consider some ...

NI Trend Watch 2014

This report from National Instruments summarises the latest trends in the ...

Capactive sensing

This whitepaper looks at a number of capacitive sensing applications to ...

UWB antennas

The Antenna Company, a specialist in the design of high-performance embedded ...

Spurring on the IoT

A team of Stanford engineers has built a radio the size of an ant – a device so ...

Digital consciousness

​Would you consider uploading your brain to the cloud if it meant you could ...

Data privacy concerns

Professor Antonio Capone of the Politecnico di Milano University talks to Neil ...

A connected vision

Jamie Hayes, Mobile Network Operators Director at BT Wholesale, talks to Neil ...