Abstract
New methods for achieving high-quality conducting oxide metasurfaces are of great importance for a range of emerging applications from infrared thermal control coatings to epsilon-near-zero nonlinear optics. This work demonstrates the viability of plasma patterning as a technique to selectively and locally modulate the carrier density in planar Al-doped ZnO (AZO) metasurfaces without any associated topographical surface profile. This technique stands in strong contrast to conventional physical patterning which results in nonplanar textured surfaces. The approach can open up a new route to form novel photonic devices with planar metasurfaces, for example, antireflective coatings and multi-layer devices. To demonstrate the performance of the carrier-modulated AZO metasurfaces, two types of devices are realized using the demonstrated plasma patterning. A metasurface optical solar reflector is shown to produce infrared emissivity equivalent to a conventional etched design. Second, a multiband metasurface is achieved by integrating a Au visible-range metasurface on top of the planar AZO infrared metasurface. Independent control of spectral bands without significant cross-talk between infrared and visible functionalities is achieved. Local carrier tuning of conducting oxide films offers a conceptually new approach for oxide-based photonics and nanoelectronics and opens up new routes for integrated planar metasurfaces in optical technology.
Highlights
Thermal control coatings to epsilon-near-zero nonlinear optics
The field of Transparent conducting oxides (TCOs) as advanced materials for photonics applicaphotonics and nanoelectronics and opens up new routes for integrated planar tions has emerged to exploit their unique metasurfaces in optical technology
We demonstrate that local patterning of carrier density in Al-doped ZnO (AZO) films through an O2 plasma treatment enables the formation of planar IR metasurfaces that lack any associated surface topography
Summary
For both meta-OSRs, the FTIR absorption spectrum shows a significantly broader absorption at around 7 and 12 μm than that of the OSR stack without metasurface patterning (labeled as film) This effect is attributed to the broadband plasmonic enhancement in this spectral range as detailed in the previous work and resulting in an increased blackbody emissivity.[24] The slight discrepancy in spectra between plasma patterning and etch meta-OSRs can be attributed to the optical difference between low carrier AZO and air. The IR emissivity is a radiation cooling performance indicator of an OSR and further detail on IR emissivity definition and calculation is available in our previous work.[24] The excellent agreement between plasma-patterned and etch patterned reflector spectra unambiguously shows that plasma-patterning technique can be used as an alternative route to form metasurface whilst maintaining a physically planar film This is highly advantageous for further device processing such as the addition of an antireflective coating stack. We believe that plasma patterning techniques have broad potentials for electronic and photonic applications to achieve novel structures once unimaginable or beyond the existing manufacture capability
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
