Embedded Metal Oxide Plasmonics Using Local Plasma Oxidation of AZO for Planar Metasurfaces

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.

Wafer‐Scale 200 mm Metal Oxide Infrared Metasurface with Tailored Differential Emissivity Response in the Atmospheric Windows

“…For the metasurface, we choose AZO with a carrier density of 6 × 10 20 cm −3 , consistent with our previous works and the highest carrier density achieved in our experimental system. [ 63 ] The metasurface (Figure 1b) is designed as a square array of AZO features with varying sizes and gap spacing between adjacent structures. Figure 1c shows the simulated optical response of the complete design for various feature sizes from 0.94 to 1.74 µm and a fixed gap size of 0.2 µm.…”

“…The Al 2 O 3 was grown at 175 °C using trimethylaluminum (TMA) and water. The Al:ZnO was grown at 250 °C using TMA and diethyl zinc (DEZ) and water with a TMA:DEZ cycle ratio of 4% (detailed in previous works) [18,63] and carrier concentration was measured to be 6 × 10 20 cm −3 . The AZO was subsequently patterned using Nikon NSR-S204B 248 nm DUV system with KrF M91Y photoresist (680 nm thickness after development).…”

“…These are large-bandgap semiconductors with free electrons in the range of 10 19 -10 21 cm −3 . [62,63] Infrared metasurfaces based on conducting oxides have so far been reported to operate in the broadband range [18,64] and it is a challenge to form a multiband infrared metasurface using AZO. We report here a design using a novel 5-layer stack incorporating a thin Ti layer and the AZO metasurface as characteristic features.…”

Functional Nanomaterials from Waste and Low‐Value Natural Products: A Technological Approach Level

“…[ 140,141 ] To date, many types of plasma systems have been designed such as, e.g., DC discharge‐based platforms, [ 142–144 ] microwave systems, [ 145–147 ] inductively coupled plasma (ICP), [ 148–150 ] and capacitively coupled plasma (CCP) [ 151,152 ] systems, radio‐frequency (RF) and magnetrons, [ 153–156 ] and many others. [ 157–160 ]…”

When Ellipsometry Works Best: A Case Study With Transparent Conductive Oxides

“…By manipulating the nanoarchitecture, a wide variety of plasmonic responses have been demonstrated. Such architectures were able to advance applications in nanophotonics, − solar energy harvesting, , biosensing, , optical encoding, photocatalysis, , and waveguiding, as well as the most impactful area of cancer treatment. , …”