Thin Film Stacks Research Articles

Data-driven investigation of thickness variations in multilayer thin film coatings

Abstract Design and fabrication of multilayer thin film coatings for photonics applications require careful consideration of various parameters such as layer thickness, refractive indices and number of stacks. A growing trend uses machine learning for efficient navigation in the complex parameter space of photonics applications to efficiently extract valuable insights from the extensive datasets and to predict the optical performance. We developed an approach that combines Monte-Carlo and Finite-Difference Time-Domain simulations to model multilayer thin films. After conducting 95 200 runs, the data were analyzed using Neural Network fitting to explore how thickness variations influence the optical performance. An experiment validation on magnetron sputtered coated samples demonstrates the high accuracy of our method in predicting the optical performance of the thin film stacks (R 2 > 0.99), contributing to the understanding and enhancement of photonics stack properties for diverse optical applications using machine learning approaches.

Photocatalytic Edge Growth of Conductive Gold Lines On Microstructured TiO2-ITO Substrates.

Titanium dioxide is well-known for its excellent photocatalytic properties. UV-controlled photodeposition of gold on TiO2 is achieved by photocatalytic reduction of precursor ions from a tetrachloroauric solution. During the growth process on the surface, clusters grow from nucleation centers and coalescence is observed for sufficiently long UV illumination times, resulting in gold structures with complex shapes. Here, we hypothesize and demonstrate that the growth process is altered by employing an ITO sublayer below the TiO2 layer. Photocatalytic gold growth experiments on a microstructured thin film stack of 6 nm ITO and 70 nm TiO2 lead to strongly localized gold growth along the edge of the patterned area. A conductive gold line with a height of 3.8 μm is achieved along the edge of the TiO2-coated region, while gold growth on the surface of TiO2 is effectively suppressed. For substrates coated only with ITO or TiO2, no edge growth is observed. Furthermore, for an 845 nm thick TiO2 layer, either with or without ITO sublayer, gold growth on the TiO2 surface is dominant. Thus, for the effective steering of electrons to the edge, both the ITO sublayer and a sufficiently thin TiO2 layer are necessary. This modified method of photocatalytic deposition─electrons photogeneration in a thin layer, collection in a dedicated conductive sublayer, and growth by reduction at a different position─opens opportunities for localized material deposition. We are in particular aiming at extending the toolbox of neuromorphic engineering by providing a technical implementation of stimulus-controlled dynamic formation of directional conductive interlinks.

Analysis of CeO2/SiO2 double-layer thin film stack with antireflection effect for silicon solar cells

This study introduces CeO2/SiO2 double-layer film stacks and its antireflection coating effect. Optical properties were analyzed by spectrophotometer measurements; surface morphology and cross-sections were observed by Scanning Electron Microscopy (SEM); elemental distributions and crystallographic properties were determined by Energy Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD) measurements. Average reflectance of single-layer 0.3MSiO2, 0.6MSiO2, and 0.3MCeO2 thin films were 30.54%, 20.12%, and 14.23%, respectively. Average reflectance was decreased significantly down to 5.9% by 0.3MCeO2/0.6MSiO2 double-layer thin films comparing to those of the results of single-layer films and bare silicon surface reflection (~40%). Antireflective effect of the films on solar cells was estimated by simulation using the measured reflection data. Simulated solar cells indicate that 0.3MCeO2/0.6MSiO2 double-layer antireflective coatings are capable to increase the efficiency significantly and conversion efficiency of 21.7% could be achieved.

Multifunctional daytime radiative cooler resistant to UV aging

Passive radiative cooling presents a promising approach to mitigate global warming and reduce energy consumption. Existing coolers, however, face challenges in practical prolonged adoption due to their unappealing design, susceptibility to environmental pollutants, as well as degradation of polymers by ultraviolet (UV) irradiation from sunlight. This study introduces a multifunctional daytime radiative cooler (MDRC) with a dual-layered structure, combining practical functionality with aesthetic value. Its base layer consists of an Ag–TiO2–Ag thin film stack, imparting vibrant cyan, magenta, and yellow colors, even maintaining visually appealing from various incident angles, up to 75°, to ensure consistent color display. The top layer, comprising S–SiO2 nanospheres with UV resistance rather than polymers, not only forms a superhydrophobic surface with a contact angle of 155.502°, enhancing the self-cleaning capability of the MDRC against contamination and dust, but also renders the MDRC with extraordinary anti-aging capacity. Outdoor experiments has shown that the MDRC maintains operation at temperatures above ambient under direct solar irradiation, achieving a substantial temperature reduction of 6.82 °C compared to the same colored commercial coating. After three months of outdoor exposure, the MDRC demonstrated minimal degradation in performance, with decreases of only 0.29 °C during the day and 0.12 °C at night, underscoring its superior UV-resistant aging properties. This MDRC represents a robust solution for diverse durable outdoor raidative cooling applications, advancing toward real-world utilization.

Optical intensity figures of merit of insulator-metal-insulator and metal-insulator-metal thin-film stacks

This paper discusses the quality factors Q and the intensity figures of merit (IFoM) evaluating the intensity and leakage of modes of the reflection flux and of the plane-wave and locally excited transmitted fluxes of insulator-metal-insulator (IMI) and metal-insulator-metal (MIM) 2D planar thin-film stacks, here air-Au-glass and air-Au-SiO2-Au-glass stacks respectively. These thin film stacks sustain a single surface plasmon polariton (SPP) and multiple planar waveguide (PWG) modes. The Q and IFoM of the 3D dispersion graph (in-plane wave vector k ρ /k 0 ∈ [0, 1.52]/frequency ω ∈ [0.5, 2.7] eV/observable dispersion) are calculated and analyzed along 2D cuts where either the in-plane wave vector k ρ /k 0 or the frequency ω are varied the other independent variable being kept fixed. Here these two cuts are called spatial (ω fixed) and frequency (k ρ /k 0 fixed) domains. Due to a lower leakage, the Q and IFoM of the IMI and MIM thin film stack modes are significantly larger in the spatial domain than in the frequency domain. In the spatial domain the IMI and MIM stack modes dominate at low and high frequencies respectively. In the frequency domain, the Q and IFoM of a MIM stack mode is always larger than that of an IMI stack. Our results span a large domain of frequencies in the SPP and RPP region and of the in-plane wave vector whereas the results in the literature presented above concern only particular laser frequencies and limited in-plane wave vector values. Our Q and IFoM of the 2D planar thin film stack modes, obtained with optimized independent variables, are larger than those of other planar thin film stacks but smaller than some 2D/3D nano scale samples with an involved geometry. The simplicity of producing these simple IMI and MIM stacks permit their use in the applications.

Terahertz Spin-Conductance Spectroscopy: Probing Coherent and Incoherent Ultrafast Spin Tunneling.

Thin-film stacks | consisting of a ferromagnetic-metal layer and a heavy-metal layer are spintronic model systems. Here, we present a method to measure the ultrabroadband spin conductance across a layer between and at terahertz frequencies, which are the natural frequencies of spin-transport dynamics. We apply our approach to MgO tunneling barriers with thickness d = 0-6 Å. In the time domain, the spin conductance Gs has two components. An instantaneous feature arises from processes like coherent spin tunneling. Remarkably, a longer-lived component is a hallmark of incoherent resonant spin tunneling mediated by MgO defect states, because its relaxation time grows monotonically with d to as much as 270 fs at d = 6.0 Å. Our results are in full agreement with an analytical model. They indicate that terahertz spin-conductance spectroscopy will yield new and relevant insights into ultrafast spin transport in a wide range of spintronic nanostructures.

VO2 thin films: various microstructures for hysteresis manipulations

Vanadium dioxide reveals a phase change transition at 68 °C associated to typical hysteresis curves with strong variations in physico-chemical properties. The study presented here aims to investigate the influence of the structure and the microstructure of VO2 condensed matter on optical transmittance and electrical resistivity hysteresis curves during the metal-insulator transition. The characteristics of VO2 thin films synthesized through conventional laser ablation and of VO2 nanoparticle stacks generated via a laser vaporization cluster source are investigated. This study reveals the capability to modulate the transition temperature by as much as 20 °C, the transition width within the range of 4–30 °C, and the resistivity dynamics across the semiconducting-to-metallic phase transition by more than two orders of magnitude. These effects appear to arise because of the change of microstructure, the physical percolation of nanoparticles and associated collective effects.More complex hysteresis behaviors, taking benefit of the fabrication processes presented in this paper, and coupling the two previous distinct VO2 architectures (thin film and nanoparticles stack) lead to optical transmittance curves with three transition levels. This approach offers flexibility beyond binary responses, facilitating the design of innovative optoelectronic devices with n-stages modulation capabilities. Near room temperature applications of VO2 metal-insulator transition are underscored, highlighting opportunities for tailored architectures to exploit its properties effectively.

Material screening for future diffusion barriers in Cu interconnects: Modeling of binary and ternary metal alloys and detailed analysis of their barrier performance

One of the challenges in the semiconductor industry is to find new barrier materials and copper (Cu) alternative solutions in interconnects. In this work, we focused to find alternative diffusion barrier materials. Different binary (CoMo, CoRu, CoTa, CoW, MoRu, RuTa, RuW) and ternary (CoMoTa, CoRuTa, MoRuTa) metal alloys were evaluated theoretically with the Miedema model to find the amorphous phase composition range. Afterward, thin films of the alloys with various compositions were deposited by magnetron sputtering and theoretical values were compared to the experimental results. From the experimental measurements, which included grazing incidence x-ray diffraction analysis and resistivity measurements, suitable binary and ternary alloys were chosen for diffusion analysis. By annealing thin film stacks at temperatures ranging from 500 to 675°C, diffusion was induced and detected by x-ray photoelectron spectroscopy depth profiles. Seventeen alloys were evaluated by their diffusion barrier effectiveness, and five of those, which include Ru60Ta40, Ru45W55, Mo47Ru53, Mo36Ru50Ta14, and Co40Mo35Ta25, showed excellent barrier properties against copper diffusion. Furthermore, all of the stated materials have a lower resistivity than TaN. Last, the adhesion of the best performing alloys to SiCOH and Cu was evaluated by the modified edge lift-off test. Only Ru45W55 had reasonable adhesion at both interfaces. The other materials showed low adhesion strength to Cu, which would make an adhesion promoter (liner), such as cobalt, necessary for the integration.

Optimizing Ti/TiN Multilayers for UV, Optical and Near-IR Microwave Kinetic Inductance Detectors

Microwave Kinetic Inductance Detectors (MKIDs) combine significant advantages for photon detection like single photon counting, single pixel energy resolution, vanishing dark counts and µs time resolution with a simple design and the feasibility to scale up into the megapixel range. But high quality MKID fabrication remains challenging as established superconductors tend to either have intrinsic disadvantages, are challenging to deposit or require very low operating temperatures. As alternating stacks of thin Ti and TiN films have shown very impressive results for far-IR and sub-mm MKIDs, they promise significant improvements for UV, visible to near-IR MKIDs as well, especially as they are comparably easy to fabricate and control. In this paper, we present our ongoing project to adapt proximity coupled superconducting films for photon counting MKIDs. Some of the main advantages of Ti/TiN multilayers are their good control of critical temperature (Tc) and their great homogeneity of Tc even over large wafers, promising improved pixel yield especially for large arrays. We demonstrate the effect different temperatures during fabrication have on the detector performance and discuss excess phase noise observed caused by surface oxidization of exposed Si. Our first prototypes achieved photon energy resolving powers of up to 3.1 but turned out to be much too insensitive. As the work presented is still in progress, we also discuss further improvements planned for the near future.

Broad table-like magnetocaloric effect in GdFeCo thin-films for room temperature Ericsson-cycle magnetic refrigeration

We demonstrate magnetocaloric entropy change and compensation temperatures in ferrimagnetic Gdx(Fe10Co90)100−x amorphous thin films with transition metal-rich and rare earth-rich configurations. Thin films are sputtered with same Gd/FeCo elemental ratio at different thicknesses and of various Gd/FeCo ratios at a constant thickness to understand the effect of these two parameters on an antiferromagnetically coupled magnetic sub-lattice system. Temperature- and field-dependent magnetic measurements [M(H,T)] and magnetocaloric studies are performed over a broad range of temperature (70–600 K) by applying a magnetic field of ±15 kOe on sputter deposited 90 nm thin films of Gdx(Fe10Co90)1−x(x = 30,40,50,55,70). The compensation temperature is found to increase with increasing Gd concentration for thin films of the same thickness. A high magnetocaloric entropy change around 0.97 J/kg K (ΔH = ± 15 kOe) is observed for thin films having the same Gd/FeCo elemental ratio. Furthermore, we observed a “table-like” magnetocaloric entropy change in GdFeCo thin film stacks with a high operational window (60 K) at a low applied field for an Ericsson magnetic regenerator around room temperature. The studies will provide important insight into magnetocaloric studies for Ericsson-cycle refrigeration in thin films having antiferromagnetically coupled sublattices.

Improved energy storage properties through multilayer stacking of relaxor ferroelectric and antiferroelectric thin films

Abstract Multilayers of relaxor ferroelectric (Pb0.92La0.08Zr0.52Ti0.48O3) and antiferroelectric (Pb0.96La0.04Zr0.98Ti0.02O3) thin films were fabricated on Pt/Ti/SiO2/Si substrates by Chemical Solution Deposition (CSD) method. The properties of the independent relaxor ferroelectric (RFE denoted as R) and antiferroelectric (AFE denoted as A) thin films were compared with their various stack configurations made by alternatively coating the R and A layers in the patterns of R/A, R/A/R, R/A/R/A/R/A, A/R, A/R/A, and A/R/A/R/A/R. The crystallographic studies confirmed the coexistence of both RFE and AFE phases in the multilayer stacks which was further verified by electrical characterizations. The multilayer stack showed improved power density (PD), energy efficiency (η), and reduced dielectric loss compared to individual R and A films. Among all the multilayer configurations, the stack with A/R/A/R/A/R layer exhibited significant improvement in energy efficiency (94%) which is higher than the reported results so far on multilayer structures.

Enhancing dielectric-silicon interfaces through surface electric fields during firing

Minimising charge losses at silicon interfaces is a major development area for highly efficient solar cells. Here we report on the interface improvements achieved by establishing a surface electric field during low-temperature firing of dielectric thin films. By inducing a corona electric field on the surface of a thin film stack, we observe significant modifications to the silicon-dielectric interface upon annealing, which correlate with the characteristics of interface defects. The passivation properties of the interfaces strongly depend on the polarity and strength of the electric field during firing, as well as the dielectric materials in the layer stack. We show that the surface electric fields not only influence surface carrier population but also affect the resulting chemical interface properties post-annealing. It is postulated that hydrogen migration plays a role in these observed effects. Leveraging the corona-induced electric field enables fine-tuning of both the chemical and field-effect passivation in thin film surface dielectrics, resulting in recombination current densities as low as 2.8 fA cm−2 in research-grade float zone silicon, and 14 fA cm−2 in industrial-grade textured silicon. The simplicity and versatility of the thin film electric polarisation enable a new strategy for controlling and exploiting the chemical enhancement of interfaces in solar cell devices, from current TOPCon and PERC devices to future multijunction silicon-based cells.

Extreme Dewetting Resistance and Improved Visible Transmission of Ag Layers Using Sub-Nanometer Ti Capping Layers.

As technology development drives the thickness of thin film depositions down into the nano regime, understanding and controlling the dewetting of thin films has become essential for many applications. The dewetting of ultra-thin Ag (9 nm) films with Ti (0.5 nm) adhesion and capping layers on glass substrates was investigated in this work. Various thin film stacks were created using magnetron sputtering and were analyzed using scanning electron microscopy/energy dispersive X-rays, Vis/IR spectrometry, and four four-point probe resistivity measurements. Upon annealing for 5 h in air at 250 °C, the addition of a 0.5 nm thick Ti capping layer reduced the dewet area by an order of magnitude. This is reflected in film resistivity, which remained 2 orders of magnitude lower than uncapped variants. This Ti/Ag/Ti structure was then deployed in a typical low-emissivity window coating structure with additional antireflective layers of AZO, resulting in a superior performance upon annealing. These results demonstrate an easy, manufacturable process that improves the longevity of devices and products containing thin Ag films.

Fabrication of a piezoelectric micromachined ultrasonic transducer (PMUT) with dual heterogeneous piezoelectric thin film stacking

In this study, a piezoelectric micromachined ultrasonic transducer (pMUT) was developed using dual heterogeneous piezoelectric thin films stacked on top of each other. One piezoelectric layer is specialized for the actuation, while the other is specialized for the reception of the ultrasonic waves. This combined use of two materials promises to realize a pMUT transceiver array with an excellent transmitting and receiving performance and a high fill factor. Taking fabrication feasibility into consideration, AlN/Pb(Mg1/3, Nb2/3)O3-PbTiO3 (PMN-PT) and Pb(Zr, Ti)O3 (PZT)/AlN pMUTs were selected as two candidates for prototyping as the dual-layer pMUTs. The driving tests were performed by actuation of each piezoelectric layer and a resonance frequencies around 265 kHz and 203 kHz were confirmed for AlN/PMN-PT and PZT/AlN pMUT, respectively. The diaphragm of AlN/PMN-PT pMUT has a displacement sensitivity of 3538 nm V−1 and 306 nm V−1 when actuating PMN-PT layer and AlN layer at resonance frequency, respectively. While the diaphragm of PZT/AlN pMUT has a displacement sensitivity of 1036 nm V−1 and 744 nm V−1 when actuating the PZT layer and the AlN layer at the resonance frequency, respectively.

Improvement of fluorine attack induced word-line leakage in 3D NAND flash memory

In this work, the influence of fluorine (F) erosion on tungsten (W) gate process is studied, and the measure to mitigate the word line (WL) leakage resulting from F erosion in 3D NAND flash memory is proposed. As the number of layers in 3D NAND increases, the tungsten (W) gate word line (WL) layer fill process becomes more challenging in the post-gate process. As the fill path length increases, the tungsten gates become more susceptible to voiding during deposition, resulting in the accumulation of fluorine (F) by-products, and causing fluorine attack issues. In particular, under the influence of subsequent high-temperature processes, the by-products containing fluorine can diffuse into the surrounding structure and corrode the surrounding oxide layer. This leads to WL leakage, thereby affecting device yield and reliability. This paper begins by analyzing the microscopic principles of fluorine erosion in 3D NAND. We also propose a low-pressure annealing method to address the issue of fluorine erosion. Then, we conduct the experiments on annealing planar thin film stacks and 3D filled structures under atmospheric condition and low-pressure condition. We use various methods to characterize the concentration and distribution of residual fluorine elements. The experimental results demonstrate that under appropriate conditions, the residual fluorine in the tungsten gate can be effectively released by low-pressure annealing, thus reducing the leakage index of the word line. Additionally, as the outer CH is closer to the fluorine discharge channel, the influence of low-pressure annealing on the outer CH is more pronounced than on the inner CH. The low-pressure annealing can significantly reduce the fluorine content in the tungsten gate. This method can also mitigate the issue of fluorine attack oxides and reducethe WL leakage. Using low-pressure annealing treatment can also enhance the quality of 3D NAND flash technology.

Study on Ag-Ti Thin Film Structure with Compositional Gradient Fabricated by Sputtering Process

In this study, a composition-gradient thin film was applied for the formation of intermediate layer of Ti seed layer for an stable electrode stack Ag metal layer. Various composition of Ag-Ti hetero metal layer were simultaneously deposited by using the sputtering process with Ti and Ag target, respectively. An intermediate layer was deposited at a gradient composition ratio such as 5:5 and 7:3. In addition, the optimal deposition conditions were evaluated by confirming the plasma codition such as density of plasma ion, plasma potential with the Langmuir Probe (Hiden ESPion). Flow rate, power, and composition ratio were optimized as variables for thin film structures of compositional gradient thin films. In addition, thin film samples were heat treated at 200 ℃, 300 ℃, and 400 ℃ to relieve the residual stress between the interface of laminated thin films. Under these conditions, a composition-gradient thin film was evaluated by XRD (X-Ray Diffraction, SmartLab Rigaku 9kW), SEM (Scanning Electron Microscope, Nova NanoSEM 450), and EDS (energy dispersive X-ray spectroscopy). As a result of the measurement, it was confirmed that interfacial diffusion occurred due to the composition gradient thin film. When the composition gradient intermediate layer was applied to thin film stack, the residual stress increased more than that of single thin film stack. However, after stress relief annealing, residual stress was dramatically decreased compared to single stack.

Static and dynamical behaviour of magnetically coupled Co/Cu/CoFeB trilayers

Engineering the magnetic behaviour of stacks of ferromagnetic and non-magnetic thin films is mainly controlled by the anisotropy of individual layers plus the interlayer exchange coupling constant. Then, Co/Cu/CoFeB trilayers with different Cu layer thicknesses, tCu, were fabricated by sputtering. The effects of tCu on the magnetization reversal processes, the interlayer coupling, FMR frequencies and damping parameters were investigated. The analysis of the hysteresis loops have demonstrated how the two ferromagnetic films can be strongly coupled and behave like a single system for tCu ≤ 3 nm, or like two almost independent or uncoupled layers for tCu ≥ 3 nm. It is shown that the interlayer coupling is at the origin of the observed two FMR resonance modes: the acoustic and the optic modes. Particularly, the resonance frequency of the optic mode is very sensitive to the interlayer coupling constant and high resonance frequencies can be achieved (over 25 GHz) for ferromagnetically coupled Co/CoFeB bilayers with interlayer exchange coupling Jeff = (2.7 ± 0.8) erg/cm2. However, the technological application of such high resonance frequencies of the optic mode can be limited by the increase in the damping parameter mainly due to the spin-pumping effect.

VIS-NIR TMOKE enhanced dielectric-metal hybrid structure for high performance dual-channel sensing.

Magneto-plasmon sensors based on the transverse magneto-optical Kerr effect (TMOKE) have been extensively studied in recent years. In this paper, we theoretically propose a hybrid structure composed of a one-dimensional bismuth iron garnet: yttrium iron garnet (BIG: YIG) nanowire arrays and thin film stack, which is grown on an infinite thick silicon wafer. The thin film stack, from top to bottom, consists of the following layers: BIG: YIG, SiO2, and Au. By exciting the magnetic dipole resonance mode between the cylindrical nanowires and the SPP mode on the surface of the Au film, dual-channel sensing has been achieved in both visible and infrared spectra. The results demonstrate that the TMOKE response spectrum of the structure supports ultra-narrow linewidths of 0.03 nm in the visible light range and 1.54 nm in the infrared range. By changing the refractive index of the analyte, the detected sensitivity of the sensor system in visible and infrared bands is 553 nm RIU-1 and 285 nm RIU-1, and the Figure of merit (FOM) can reach up to 69125 RIU-1 and 303 RIU-1, respectively. This work provides a theoretical basis and a feasible approach for the design of dual channel gas sensors.

Spin Pumping in Moderately Perpendicular W/CoFeB/HfOx Thin Films

Large perpendicular magnetic anisotropy (PMA) and spin-orbit torques are two essential requirements for high-density and energy-efficient spintronic devices. Recent advances in magneto-electric and magneto-ionic control of PMA and spin-orbit torques have opened a pathway to explore different oxide materials with large dielectric constant and high ion mobility. Motivated by interesting memristive properties of HfOx, here, using broadband ferromagnetic resonance measurements, we study the spin pumping in-plane to perpendicularly magnetized W(5[Formula: see text]nm)/CoFeB(tCFB) system capped with 4[Formula: see text]nm HfOx thin films. We find a large spin pumping and significant PMA strength for HfOx-based thin films. Using ferromagnetic thickness dependence, we also calculate the spin mixing conductance in the trilayer system which is found to be similar to MgO-based thin film stacks. These results will be highly useful for various spintronic applications with electro-static, ionic and memristive gating.

Co‐sputtering of A Thin Film Broadband Absorber Based on Self‐Organized Plasmonic Cu Nanoparticles

AbstractThe efficient conversion of solar energy to heat is a prime challenge for solar thermal absorbers, and various material classes and device concepts are discussed. One exciting class of solar thermal absorbers are plasmonic broadband absorbers that rely on light absorption thanks to plasmonic resonances sustained in metallic nanoparticles. This work focuses on Cu/Al2O3 plasmonic absorbers, which consist of a thin film stack of a metallic Cu‐mirror, a dielectric Al2O3 spacer, and an Al2O3/Cu‐nanoparticle nanocomposite. This work explores two preparation routes for the Al2O3/Cu‐nanoparticle nanocomposite, which rely on the self‐organization of Cu nanoparticles from sputtered atoms, either in the gas phase (i.e., via gas aggregation source) or on the thin film surface (i.e., via simultaneous co‐sputtering). While in either case, Cu‐Al2O3‐Al2O3/Cu absorbers with a low reflectivity over a broad wavelength regime are obtained, the simultaneous co‐sputtering approach enabled better control over the film roughness and showed excellent agreement with dedicated simulations of the optical properties of the plasmonic absorber using a multi‐scale modeling approach. Upon variation of the thickness and filling factor of the Al2O3/Cu nanocomposite layer, the optical properties of the plasmonic absorbers are tailored, reaching an integrated reflectance down to 0.17 (from 250 to 1600 nm).