Next Article in Journal
Anisotropy of Mechanical Properties and Residual Stress in Additively Manufactured 316L Specimens
Next Article in Special Issue
Optimal Design of an Ultrasound Transducer for Efficient Acousto-Optic Modulation of Terahertz Radiation
Previous Article in Journal
Study of an Ecological Cement-Based Composite with a Sustainable Raw Material, Sunflower Stalk Ash
Previous Article in Special Issue
Temperature Effects in an Acousto-Optic Modulator of Terahertz Radiation Based on Liquefied SF6 Gas
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Materials
Volume 14
Issue 23
10.3390/ma14237178
materials-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Optically Transparent and Highly Conductive Electrodes for Acousto-Optical Devices

by
Alexey Osipkov
1,*,
Mstislav Makeev
1,*,
Elizaveta Konopleva
1,
Natalia Kudrina
1,
Leonid Gorobinskiy
1,
Pavel Mikhalev
1,
Dmitriy Ryzhenko
1 and
Gleb Yurkov
1,2
1
Laboratory of EMI Shielding Materials, Bauman Moscow State Technical University, 105005 Moscow, Russia
2
N.N. Semenov Federal Research Center for Chemical Physics Russian Academy of Sciences, 119991 Moscow, Russia
*
Authors to whom correspondence should be addressed.
Materials 2021, 14(23), 7178; https://doi.org/10.3390/ma14237178
Submission received: 1 November 2021 / Revised: 16 November 2021 / Accepted: 18 November 2021 / Published: 25 November 2021
(This article belongs to the Special Issue Acousto-Optical Spectral Technologies)
Browse Figures
Versions Notes

Abstract

:
The study was devoted to the creation of transparent electrodes based on highly conductive mesh structures. The analysis and reasonable choice of technological approaches to the production of such materials with a high Q factor (the ratio of transparency and electrical conductivity) were carried out. The developed manufacturing technology consists of the formation of grooves in a transparent substrate by photolithography methods, followed by reactive ion plasma etching and their metallization by chemical deposition using the silver mirror reaction. Experimental samples of a transparent electrode fabricated using this technology have a sheet resistance of about 0.1 Ω/sq with a light transmittance in the visible wavelength range of more than 60%.

1. Introduction

Electrode element is an indispensable component of modern acousto-optical devices. It defines the shape of the acoustic field induced in the crystalline media [1,2]. Accurate apodization of the electrodes provides diffraction efficiency increase, higher apertures and better acoustic field homogeneity [3].
Transparent electrodes are necessary for acousto-optic devices, where the direction of light propagation coincides with sound wave (Figure 1). Such collinear geometry of acousto-optic interaction is widely used, for example, in acousto-optical tunable filters with high spectral resolution [4], which are necessary for Raman spectroscopy [5] and spectral-domain optical coherence tomography [6]. Propagation of light along ultrasound may be also potentially effective for multi-beam diffraction configurations [7] and other applications. Applying optically transparent electrodes in these devices may simplify its design and reduce its dimensions.
In conventional schemes of such electrodes, an ultrasonic wave may be formed by a transparent piezoelectric transducer based on ceramic materials with a perovskite structure (titanate-zirconate of a divalent metal (for example, lead), etc.) or polymer films (for example, polyvinylidene fluoride and its copolymers) with a thickness up to several tens of micrometers [8,9,10,11,12,13,14].
In addition, transparent electrodes are widely used in solar panels, touch screens, organic and inorganic diodes, etc. [15]. Among the approaches to the creation of such electrodes are the usage of transparent conductive oxides [15], metal nanowires [16,17], carbon nanomaterials [18], and metal micro- and nano-grids [19]. Today, thin films based on tin indium oxide (ITO) are the most widely used [20]. Still, their usage is limited by the low ratio of transparency and electrical characteristics for many current tasks; the best samples of ITO coatings have a surface resistance of about 20 Ω/sq with transparency in the visible range of about 90% [21]. In addition, this material is expensive due to the depletion of global indium reserves [22], and requires high-temperature annealing to obtain a high Q factors ϕs (ϕs = T55010/ρs [23]), which complicate the production of high-quality transparent electrodes on flexible polymer substrates. The latter is relevant due to the recent intensive development of flexible LCD touch screen technology [24,25].
A decrease in the electrode resistance leads to an increasing the transparent piezoelectric transducer efficiency. Additionally, electrodes with high electrical conductivity and transparency are necessary to increase the efficiency of solar cells or to increase electromagnetic protection and compatibility of electronic devices and equipment.
Among the approaches to creating high-electrical-conductivity and transparent structures, ordered metal mesh structures formed on the surface or inside a transparent substrate have considerable potential. The geometry of such systems can be calculated in advance and specified during manufacture. Electrodes based on these structures have the best characteristics at the moment [21] in terms of the ratio of sheet resistance and transparency (3–5 Ω/sq with transparency of more than 85% [19]).
Currently, several approaches are being developed to produce such microgrids [21,26]. One of the general approaches consists of forming microgrooves with a high aspect ratio in an optically transparent material, such as quartz, into which metal, for example, silver or copper, is subsequently deposited [22]. The grooves can be filled with metal by magnetron or electron beam deposition, or chemical deposition from the gas phase. However, due to the high aspect ratio and the small width of the groove, their use is problematic [22]. A rapid blockage of the inlet and the cessation of mental growth inside the grooves may occur during the deposition process. Similar problems are also typical for galvanic metal deposition into structures with a similar aspect ratio [27].
In this paper, the manufacturing technologies for transparent mesh structures are analyzed. A proposed method for filling the grooves produced by lithography methods with silver using the silver mirror reaction is also described. In addition, the article describes the results of studies of the deposited metal morphology and the measurements of transparency, sheet resistance, and the S parameters in the radio and microwave wavelength ranges in the open coaxial waveguide of the obtained structures.

2. The Analysis of the Production Technologies of Transparent Mesh Structures

There are three groups among technological approaches used to obtain ordered mesh structures:
  • Approaches based on the formation of grooves of a specified geometry in a substrate or photoresist and their subsequent filling with metal. The grooves are formed using photolithography methods in combination with liquid or ion plasma etching or laser ablation;
  • Approaches based on the removal of the preliminarily deposited metal layer using the same etching methods;
  • Approaches based on additive processes (electrohydrodynamic printing).
Based on the literature data [27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77], Figure 2 plots of the technological limitations of various approaches to forming grooves in transparent materials or directly forming conductors on the substrate surface. The markers show the values of the width and depth of the groove’s or line’s height, obtained from the literature sources, and the lines show the technological limitations of the approaches.
Two studies [78,79] provide a description of the calculated model and the results of the conductive mesh structures’ calculation, obtaining a screening coefficient SE of more than 50 dB with transparency of more than 90% in the visible range. These calculated values were obtained for a width and height of the mesh conductors of 1.5 and 14 µm, respectively. Per Figure 2, structures with such parameters can be produced by the following methods: forming grooves in a transparent substrate by photolithography followed by reactive ion plasma etching (RIE), nanoimprinting (hot embossing), or multilayer electrohydrodynamic (EHD) printing.
At this stage, the first method was chosen for the practical implementation of the calculated structures due to the wide availability of the necessary technological equipment and verified technological regimes. Notably, the methods of nanoimprinting and EHD printing, with their further development, have considerable potential for creating serial technology for producing large-area, micro-mesh, transparent electrodes.

3. Materials and Methods

Experimental samples were pure quartz wafers with a thickness of 0.5 mm. A system of grooves was formed in the first step of preparation as a network. In the second step, the grooves were filled with silver metal. The topological network was an artificial, disordered mesh with a Voronoi diagram randomly distributed inside a cell of equal probability density (Figure 3).
The technological process of groove formation included these steps: the cleaning of a wafer, the coating of an α–Si:H masking layer with plasmochemical deposition using SPTS APM equipment (SPTS Technologies Ltd., Newport, UK); positive photoresist SPR700-1.0 coating by centrifuge, drying, and exposure with a ASML PAS 5500 stepper (ASML, Veldhoven, The Netherlands); followed by the development and plasmochemical etching of the α–Si:H masking layer with the Bosh process; and plasmochemical etching of grooves on the quartz wafer through the windows (holes) at the masking layer with the help of C4F8. (Figure 4).
A silver mirror reaction (a process of silver salt reduction, for example, silver nitrate) was used for filling the experimental samples with metal. The formation of a silver layer with few defects is possible only with a low rate of chemical reaction [80]. Glucose was used as a weak reducing agent, which increases silver adhesion to a surface [81]. The synthesis was carried out at 25 °C for the same reason.
Two solutions were used. The first solution was prepared by dissolution of 1.25 g of silver nitrate (AgNO3) in 30 mL of deionized water, the addition of 4 mL of 25% water ammonia (NH4OH), and the addition of 30 mL of an alkali solution (1.1 g of NaOH was dissolved in water and diluted until 30 mL of solution was formed). The initial rate of the silver mirror reaction decreased with increasing ammonia concentration; the silver nitrate solution stability and the thickness of the silver layer increased simultaneously [81]. The silver alkali ammonia solution was diluted to 100 mL, and the first solution was prepared. The second solution was prepared by dissolution of 1.1 g of glucose in water and dilution to 100 mL. A higher glucose concentration (higher than 1.3 g/L) decreases the maximal thickness of the silver layer [81] and facilitates silver particle agglomeration [24]. The shelf life of the solutions was less than 10 h. The samples for the metallization were placed into a beaker. The first solution was poured, and then the second solution was added in a volume ratio of 1:1. The reaction time was less than 10 min (usually 3–5 min). The long duration of the silver mirror reaction leads to the morphology of silver particles differing from a sphere [82], which can inhibit groove filling. The silver mirror reaction was repeated several times. The excess metal from the surface was removed after each iteration of silver deposition.
The geometric dimensions and surface morphology of the manufactured grooves and the surface morphology and structure of the deposited silver were studied by scanning electron microscopy (SEM, TESCAN ORSAY HOLDING, Brno, Czech Republic) using a VEGA 3. Imaging was performed at an accelerating voltage of 10 kV and a beam current of 10 A in secondary electron detection mode to obtain images with the highest resolution, and in back-reflected electron mode to obtain a compositional contrast.
Sheet resistance was determined by the four-probe method using a Keithley 2000 multimeter (Tektronix, Inc, Beaverton, OR, USA) and a Mill-Max 854-22-004-10-001101 four-probe head (Mill-Max Mfg. Corp., Oyster Bay, NY, USA).
The transmission coefficient in the visible wavelength range of 380 to 780 nm was determined on a Shimadzu UV-3600i Plus spectrophotometer (SHIMADZU CORPORATION, Kyoto, Japan) with a resolution of 1 nm at normal incidence of light on the sample.
Since the materials under development had considerable potential for application in radio engineering, the shielding efficiency (SE) was measured to evaluate the obtained materials’ radio engineering properties. The measurements were obtained in the frequency range from 10 MHz to 7 GHz on a specialized measuring stand based on a FieldFox N9916A vector circuit analyzer (Keysight Technologies, Santa Rosa, CA, USA) in a coaxial path (type II). The SE value was determined from the S21 transmission coefficient of the path with the sample in relation to the transmission coefficient S21 of the path without the sample. Electro-sealing gaskets composed of dense metalized fabric were used for better electrical contact between the sample and the walls of the coaxial tract. The SE dynamic measurement range of the stand is 80 dB and the measurement error is ±2 dB.

4. Results

A photo of an obtained sample is shown in Figure 5. The geometrical dimensions of the sample were an outer diameter of 16 mm and an inner diameter of 6.95 mm. The sample was fabricated in this shape due to the requirements for SE measurements in the coaxial path.
The grooves in the quartz substrate obtained by lithography and plasma chemical etching were examined by scanning electron microscopy (Figure 6). The groove walls obtained in quartz glass showed vertical deviations up to 10°, which led to distortion of the specified topology (Figure 3). The groove cross-section was trapezoidal with a depth of 16.24 µm and a width of 1.15 (in-depth) to 4.47 µm (at the surface). The deviation from the verticality of the groove walls was caused by lateral subtraction during plasma chemical etching.
The degree of groove filling with silver was evaluated after the metallization process (Figure 7). We found that the silver filled all the grooves throughout the sample, but the silver structure was porous.
The sheet resistance of the manufactured sample was (0.084 ± 0.016) Ω/sq. Measurements were taken at 22 different points on the sample surface (Figure 8a).
The frequency dependence of the SE is shown in Figure 8b. The average SE value in the frequency range of 10 MHz to 7 GHz is 54.6 dB. The horizontal behavior of the SE spectrum indicates the absence of significant metallization defects.
The transmission spectrum measurements were taken at eight different points on the sample surface using a specially designed fixture (Figure 9a). The average, maximum and minimum transmission spectrums of the test sample in the visible wavelength range are shown in Figure 9b. The light transmittance coefficient calculated for the wavelength range from 380 to 780 nm following GOST R 54164-2010 is 64.1%.

5. Discussion

The deviation from the groove walls’ geometry due to the technological peculiarities of quartz etching led to a width increase from 1.5 to 4 µm at the groove entrance. This increased the surface area of the conductive grid paths and decreased the light transmission coefficient from 90% (according to the simulation results) to 64%. In order to increase this parameter, further development of the plasma chemical etching process of a transparent substrate is required. Notably, no such problems are encountered, for example, when forming grooves on Si substrates: it is possible to produce grooves with a high aspect ratio without distorting the geometry using the Bosh process, but such samples are only transparent in the IR range (Figure 10).
Transparency can also be increased by applying antireflective coatings based on metal oxides to the sample surface. These coatings will protect the metal mesh structure from oxidation in addition to improving optical properties.
The values of SE and sheet resistance obtained on the experimental sample were close to the calculated values. The silver synthesized in the grooves using the silver mirror reaction had a porous structure, and its electrical conductivity differed significantly from that of a monolithic material. The low value of the sheet resistance of the resulting microgrid (0.084 ± 0.016 Ω/sq) and, consequently, the high SE coefficient were caused by an increase in the cross-section of the conductors when the geometry of the conducting lines was distorted. Adjustment of the technology used for filling the grooves accompanied by an increase in the density of the formed channel can significantly increase the values of these parameters.

6. Conclusions

We developed a technology for producing transparent conductive electrodes. The technology consists of forming grooves in a transparent wafer by photolithography methods, followed by reactive ion plasma etching and its metallization by chemical deposition with a silver mirror reaction (Tollen′s reagent). This technology was chosen due to the high availability of necessary technological equipment and the verified technological regimes. Notably, methods of nanoimprint lithography and multilayer electrohydrodynamic (EHD) printing have considerable potential with the development of the methods for the creation of serial technology micro-mesh transparent electrodes with a large surface area.
The experimental sample was prepared according to developed technology with a sheet resistance of 0.09 Ω/sq and a visible light transmittance of more than 60%. The development of technology will allow for upgrading the functional characteristics of the prepared samples. In particular, the verticality of the groove wall needs to be improved for transparency improvement. The grade of the metal filling and the density of the metal need to be increased for enhancing the SE and decreasing sheet resistance. The first problem can be solved by reworking the reactive ion plasma etching of transparent wafers. The second task may be achieved using a sintering process for the prepared samples.
The proposed approach to the design of optically transparent electrodes may be effective for multiple scientific and industrial applications including acousto-optics, photoacoustics, lithography, radio shielding applications, etc.

Author Contributions

Conceptualization, M.M. and G.Y.; funding acquisition, D.R. and G.Y.; Investigation, A.O., E.K., N.K. and L.G.; methodology, A.O., M.M., P.M. and D.R.; project administration, P.M.; resources, D.R.; supervision, D.R. and G.Y.; validation, E.K.; writing—original draft, A.O., M.M., E.K. and N.K.; writing—review and editing, A.O., M.M., P.M. and G.Y. All authors have read and agreed to the published version of the manuscript.

Funding

This research work was supported by the Ministry of Education and Science of the Russian Federation under state task No. 0705-2020-0032.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Acknowledgments

This research work was supported by the Ministry of Education and Science of the Russian Federation under state task No. 0705-2020-0032. The authors also express their gratitude to Bauman Moscow State Technical University staff Bibikov S.B. and Damaratskiy I.A. for the shielding coefficients measurement.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Maák, P.; Lenk, S.; Jakab, L.; Barócsi, A.; Richter, P. Optimization of transducer configuration for bulk acousto-optic tunable filters. Opt. Commun. 2004, 241, 87–98. [Google Scholar] [CrossRef]
  2. Dühring, M.B.; Laude, V.; Khelif, A. Improving surface acousto-Optical interaction by high aspect ratio electrodes. J. Appl. Phys. 2009, 106, 113518. [Google Scholar] [CrossRef] [Green Version]
  3. Pannell, C.N.; Ward, J.D.; Wachman, E.S.; Zhang, B.G.; Reed, M.K. A high-Performance passband-Agile hyperspectral imager using a large aperture acousto-Optic tuneable filter. Photonic Instrum. Eng. II 2015, 9369, 936906. [Google Scholar]
  4. Tran, C.D.; Huang, G.C. Characterization of the collinear beam acousto-Optic tunable filter and its comparison with the noncollinear and the integrated acousto-Optic tunable filter. Opt. Eng. 1999, 38, 1143–1148. [Google Scholar] [CrossRef]
  5. Gupta, N.; Fell, N.F., Jr. A compact collinear AOTF Raman spectrometer. Talanta 1997, 45, 279–284. [Google Scholar] [CrossRef]
  6. Viskovatykh, A.; Machikhin, A.; Pozhar, V.; Pustovoit, V.I.; Viskovatykh, D.A. Combined optical-coherence and spectral microscopy based on tunable acousto-optic filters of images. Tech. Phys. Lett. 2014, 40, 157–160. [Google Scholar] [CrossRef]
  7. Machikhin, A.; Batshev, V.; Pozhar, V.; Naumov, A.; Gorevoy, A. Acousto-optic tunable spectral filtration of stereoscopic images. Opt. Lett. 2018, 43, 1087–1090. [Google Scholar] [CrossRef]
  8. Li, Z.; Ilkhechi, A.K.; Zemp, R. Transparent capacitive micromachined ultrasonic transducers (CMUTs) for photoacoustic applications. Opt. Express 2019, 27, 13204–13218. [Google Scholar] [CrossRef]
  9. Chen, X.; Chen, R.; Chen, Z.; Chen, J.; Shung, K.K.; Zhou, Q. Transparent lead lanthanum zirconate titanate (PLZT) ceramic fibers for high-Frequency ultrasonic transducer applications. Ceram. Int. 2016, 42, 18554–18559. [Google Scholar] [CrossRef]
  10. Pala, S.; Lin, L. Fully Transparent Piezoelectric Ultrasonic Transducer with 3D Printed Substrate. In Proceedings of the 20th International Conference on Solid-State Sensors, Actuators and Microsystems and Eurosensors XXXIII (Transducers and Eurosensors XXXIII), Berlin, Germany, 23–27 June 2019; pp. 234–237. [Google Scholar]
  11. Sette, D.; Girod, S.; Godard, N.; Adjeroud, N.; Chemin, J.B.; Leturcq, R.; Defay, E. Transparent piezoelectric transducers for large area ultrasonic actuators. In Proceedings of the IEEE 30th International Conference on Micro Electro Mechanical Systems (MEMS), Las Vegas, NV, USA, 22–26 January 2017; pp. 793–796. [Google Scholar]
  12. Luo, G.L.; Fung, S.; Wang, Q.; Kusano, Y.; Lasiter, J.; Kidwell, D.; Horsley, D.A. High fill factor piezoelectric micromachined ultrasonic transducers on transparent substrates. In Proceedings of the 19th International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers), Kaohsiung, Taiwan, 18–22 June 2017; pp. 1053–1056. [Google Scholar]
  13. Ren, D.; Sun, Y.; Shi, J.; Chen, R. A Review of Transparent Sensors for Photoacoustic Imaging Applications. Photonics. Multidiscip. Digit. Publ. Inst. 2021, 8, 324. [Google Scholar] [CrossRef]
  14. Shehzad, M.; Wang, S.; Wang, Y. Flexible and transparent piezoelectric loudspeaker. npj Flex. Electron. 2021, 5, 1–6. [Google Scholar]
  15. Pasquarelli, R.M.; Ginley, D.S.; O’Hayre, R. Solution processing of transparent conductors: From flask to film. Chem. Soc. Rev. 2011, 40, 5406. [Google Scholar] [CrossRef]
  16. Liu, C.H.; Yu, X. Silver nanowire-Based transparent, flexible, and conductive thin film. Nanoscale Res. Lett. 2011, 6, 1. [Google Scholar] [CrossRef] [Green Version]
  17. Tran, N.H.; Duc, A.N.; Thanh, H.D.; Kim, H.C. Fast and simple fabrication of flexible and transparent electrode based on patterned copper nanowires by mechanical lithography transfer. Thin Solid Film. 2019, 685, 26. [Google Scholar] [CrossRef]
  18. López-Naranjo, E.J.; González-Ortiz, L.J.; Apátiga, L.M.; Rivera-Muñoz, E.M.; Manzano-Ramírez, A. Transparent electrodes: A review of the use of carbon-Based nanomaterials. J. Nanomater. 2016, 2016, 4928365. [Google Scholar] [CrossRef] [Green Version]
  19. Voronin, A.S.; Simunin, M.M.; Fadeev, Y.V.; Ivanchenko, F.S.; Karpova, D.V.; Tambasov, I.A.; Khartov, S.V. Technological basis of the formation of micromesh transparent electrodes by means of a self-Organized template and the study of their properties. Tech. Phys. Lett. 2019, 45, 366. [Google Scholar] [CrossRef]
  20. Lu, H.C.; Mao, J.W.; Chiang, Y.C. Low temperature preparation of ITO thin films by the coating solutions containing solvothermally synthesized ITO nanoparticles. Surf. Coat. Technol. 2013, 231, 526. [Google Scholar] [CrossRef]
  21. Osipkov, A.; Makeev, M.; Garsiya, E.; Filyaev, A.; Sinyagaeva, A.; Kirillov, D.; Ryzhenko, D.; Yurkov, G. Radio-Shielding metamaterials transparent in the visible spectrum: Approaches to creation. IOP Conf. Ser. Mater. Sci. Eng. IOP Publ. 2021, 1060, 012007. [Google Scholar] [CrossRef]
  22. Ye, S.; Rathmell, A.R.; Chen, Z.; Stewart, I.E.; Wiley, B.J. Metal nanowire networks: The next generation of transparent conductors. Adv. Mater. 2014, 26, 6670. [Google Scholar] [CrossRef]
  23. Levy, D.; Castellón, E. Transparent Conductive Materials: Materials. Synth. Charact. Applications, 1st ed.; Wiley-VCH: Weinheim, Germany, 2019; pp. 38–42. [Google Scholar]
  24. Jiang, B.; Li, M.; Bai, F.; Yu, H.; Mwenya, T.; Li, Y.; Song, D. Morphology-Controlled synthesis of silver nanoparticles on the silicon substrate by a facile silver mirror reaction. Aip Adv. 2013, 3, 032119. [Google Scholar] [CrossRef]
  25. Tu, Y.J.; You, C.F.; Chen, Y.R.; Huang, C.P.; Huang, Y.H. Application of recycled iron oxide for adsorptive removal of strontium. J. Taiwan Inst. Chem. Eng. 2015, 53, 92–97. [Google Scholar] [CrossRef]
  26. Lee, H.B.; Jin, W.Y.; Ovhal, M.M.; Kumar, N.; Kang, J.W. Flexible transparent conducting electrodes based on metal meshes for organic optoelectronic device applications: A review. J. Mater. Chem. C 2019, 7, 1087–1110. [Google Scholar] [CrossRef]
  27. Wolf, M.; Dretschkow, T.; Wunderle, B.; Jurgensen, N.; Engelmann, G.; Ehrmann, O.; Uhlig, A.; Michel, B.; Reichl, H. High aspect ratio TSV copper filling with different seed layers. In Proceedings of the 58th Electronic Components and Technology Conference, Lake Buena Vista, FL, USA, 27–30 May 2008; IEEE: Piscataway, NJ, USA; pp. 563–570. [Google Scholar]
  28. Galiker, P.; Schneider, J.; Eghlidi, H.; Kress, S.; Sandoghdar, V.; Poulikakos, D. Direct printing of nanostructures by electrostatic autofocussing of ink nanodroplets. Nat. Commun. 2012, 3, 1–9. [Google Scholar] [CrossRef]
  29. Schneider, J.; Rohner, P.; Thureja, D.; Schmid, M.; Galliker, P.; Poulikakos, D. Electrohydrodynamic nanodrip printing of high aspect ratio metal grid transparent electrodes. Adv. Funct. Mater. 2015, 26, 833–840. [Google Scholar] [CrossRef]
  30. Seong, B.; Yoo, H.; Nguyen, V.D.; Jang, Y.; Ryu, C.; Byun, D. Metal-Mesh based transparent electrode on a 3-D curved surface by electrohydrodynamic jet printing. J. Micromech. Microeng. 2014, 24, 097002. [Google Scholar] [CrossRef]
  31. Jang, Y.; Kim, J.; Byun, D. Invisible metal-Grid transparent electrode prepared by electrohydrodynamic (EHD) jet printing. Appl. Phys. 2013, 46, 155103. [Google Scholar] [CrossRef]
  32. Zhang, B.; Lee, H.; Byun, D. Electrohydrodynamic Jet Printed 3-Dimensional (3-D) Metallic Grid: Towards High-Performance Transparent Electrodes. Adv. Eng. Mater. 2020, 22, 1901275. [Google Scholar] [CrossRef]
  33. Sujaya, K.; Do-Geun, K.; Jihoon, K. Electromagnetic interference shielding effectiveness of invisible metal-Mesh prepared by electrohydrodynamic jet printing. Jpn. Soc. Appl. Phys. 2014, 53, 05HB11. [Google Scholar]
  34. Jang, Y.; Hartarto Tambunan, I.; Tak, H.; Dat Nguyen, V.; Kang, T.; Byun, D. Non-Contact printing of high aspect ratio Ag electrodes for polycrystalline silicone solar cell with electrohydrodynamic jet printing. Appl. Phys. Lett. 2013, 102, 123901. [Google Scholar] [CrossRef]
  35. Kwak, M.K.; Ok, J.G.; Lee, J.Y.; Guo, L.J. Continuous phase-Shift lithography with a roll-Type mask and application to transparent conductor fabrication. Nanotechnology 2012, 23, 344008. [Google Scholar] [CrossRef] [Green Version]
  36. Chen, J.; Cranton, W.; Fihn, M. Handbook of Visual Display Technology; Springer: Berlin/Heidelberg, Germany, 2016. [Google Scholar]
  37. Ok, J.G.; Kwak, M.K.; Huard, C.M.; Youn, H.S.; Guo, L.J. Photo-Roll Lithography (PRL) for Continuous and Scalable Patterning with Application in Flexible Electronics. Adv. Mater. 2013, 25, 6554–6561. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  38. Eckhardt, S.; Müller-Meskamp, L.; Loeser, M.; Siebold, M.; Lasagni, A.F. Fabrication of highly efficient transparent metal thin film electrodes using Direct Laser Interference Patterning. Laser-Based Micro-Nanoprocessing IX 2015, 9351, 935116. [Google Scholar]
  39. Müller-Meskamp, L.; Schubert, S.; Roch, T.; Eckhardt, S.; Lasagni, A.F.; Leo, K. Transparent Conductive Metal Thin-Film Electrodes Structured by Direct Laser Interference Patterning. Adv. Eng. Mater. 2015, 17, 1400454. [Google Scholar] [CrossRef]
  40. Paeng, D.; Yoo, J.H.; Yeo, J.; Lee, D.; Kim, E.; Ko, S.H.; Grigoropoulos, C.P. Low-Cost Facile Fabrication of Flexible Transparent Copper Electrodes by Nanosecond Laser Ablation. Adv. Mater. 2015, 27, 1500098. [Google Scholar] [CrossRef] [PubMed]
  41. Qin, R.; Hu, M.; Zhang, N.; Guo, Z.; Yan, Z.; Li, J.; Liu, J.; Shan, G.; Yang, J. Flexible Fabrication of Flexible Electronics: A General Laser Ablation Strategy for Robust Large-Area Copper-Based Electronics. Adv. Electron. Mater. 2019, 5, 1900365. [Google Scholar] [CrossRef]
  42. Wang, Q.; Li, B.J.; Toor, F.; Ding, H. Novel laser-Based metasurface fabrication process for transparent conducting surfaces. J. Laser Appl. 2019, 31, 022505. [Google Scholar] [CrossRef]
  43. Liu, Y.H.; Xu, J.L.; Gao, X.; Sun, Y.L.; Lv, J.J.; Shen, S.; Chen, L.S.; Wang, S.D. Freestanding transparent metallic network based ultrathin, foldable and designable supercapacitors. Energy Environ. Sci. 2017, 10, 2534–2543. [Google Scholar] [CrossRef]
  44. Li, M.; Zuo, W.W.; Ricciardulli, A.G.; Yang, Y.G.; Liu, Y.H.; Wang, Q.; Wang, K.L.; Li, G.X.; Saliba, M.; Girolamo, D.D.; et al. Embedded Nickel-Mesh Transparent Electrodes for Highly Efficient and Mechanically Stable Flexible Perovskite Photovoltaics: Toward a Portable Mobile Energy Source. Adv. Mater. 2020, 32, 2003422. [Google Scholar] [CrossRef]
  45. Xu, J.L.; Liu, Y.H.; Gao, X.; Sun, Y.; Shen, S.; Cai, X.; Chen, L.; Wang, S.D. Embedded Ag Grid Electrodes as Current Collector for Ultra-Flexible Transparent Solid-State Supercapacitor. ACS Appl. Mater. Interfaces 2017, 9, 27649. [Google Scholar] [CrossRef]
  46. Liu, Y.H.; Xu, J.L.; Shen, S.; Cai, X.L.; Chen, L.S.; Wang, S.D. High-performance, ultra-flexible and transparent embedded metallic mesh electrodes by selective electrodeposition for all-solid-state supercapacitor applications. J. Mater. Chem. A 2017, 5, 9032–9041. [Google Scholar] [CrossRef]
  47. Jiang, Z.Y.; Huang, W.; Chen, L.S.; Liu, Y.H. Ultrathin, lightweight, and freestanding metallic mesh for transparent electromagnetic interference shielding. Opt. Express 2019, 27, 24194–24206. [Google Scholar] [CrossRef]
  48. Bilenberg, B.; Jacobsen, S.; Schmidt, M.S.; Skjolding, L.H.D.; Shi, P.; Bøggild, P.; Tegenfeldt, J.O.; Kristensena, A. High resolution 100 kV electron beam lithography in SU-8. Microelectron. Eng. 2006, 83, 1609–1612. [Google Scholar] [CrossRef]
  49. Taylor, A.B.; Michaux, P.; Mohsin, A.S.; Chon, J.W. Electron-beam lithography of plasmonic nanorod arrays for multilayered optical storage. Opt. Express 2014, 22, 13234–13243. [Google Scholar] [CrossRef] [PubMed]
  50. Rai-Choudhury, P. Handbook of Microlithography, Micromachining, and Microfabrication: Micromachining and Microfabrication; SPIE Press: Washington, DC, USA, 1997; Volume 2, pp. 41–99. [Google Scholar]
  51. Groep, J.; Spinelli, P.; Polman, A. Transparent Conducting Silver Nanowire Networks. Nano Lett. 2012, 12, 3138–3144. [Google Scholar] [CrossRef]
  52. Wang, L.; Xiong, W.; Nishijima, Y.; Yokota, Y.; Ueno, K.; Misawa, H.; Qiu, J.; Bi, G. Spectral properties of nanoengineered Ag/Au bilayer rods fabricated by electron beam lithography. Appl. Opt. 2011, 50, 5600–5605. [Google Scholar] [CrossRef] [PubMed]
  53. DONGJIN Photoresist Products DSAM-3000 Series. Available online: https://www.yumpu.com/en/document/read/29811371/dongjin-photoresist-products-dsam-3000-series (accessed on 31 October 2021).
  54. Zhang, C.; Khan, A.; Cai, J.; Liang, C.; Liu, Y.; Deng, J.; Huang, S.; Li, G.; Li, W.D. Stretchable Transparent Electrodes with Solution-processed Regular Metal Mesh for Electroluminescent Light-emitting Film. ACS Appl. Mater. Interfaces 2018, 10, 21009–21017. [Google Scholar] [CrossRef]
  55. Khan, A.; Lee, S.; Jang, T.; Xiong, Z.; Zhang, C.; Tang, J.; Guo, L.J.; Li, W.D. High-Performance Flexible Transparent Electrode with an Embedded Metal Mesh Fabricated by Cost-Effective Solution Process. Small 2016, 12, 3021–3030. [Google Scholar] [CrossRef]
  56. Wang, W.; Bai, B.; Zhou, Q.; Ni, K.; Lin, H. Petal-shaped metallic mesh with high electromagnetic shielding efficiency and smoothed uniform diffraction. Opt. Mater. Express 2018, 8, 3485–3493. [Google Scholar] [CrossRef]
  57. Zhao, L.; Yu, S.; Li, X.; Wu, M.; Li, L. High-Performance copper mesh transparent flexible conductors based on electroplating with vacuum-Free processing. Org. Electron. 2019, 82, 105511. [Google Scholar] [CrossRef]
  58. Xie, R.; Kava, J.; Siegel, M. Aspect ratio dependent etching on metal etch: Modeling and experiment. J. Vac. Sci. Technol. A Vac. Surf. Film. 1996, 14, 1067–1071. [Google Scholar] [CrossRef]
  59. Blumenstock, K.; Stephani, D. Anisotropic reactive ion etching of titanium. J. Vac. Sci. Technol. B 1989, 7, 627. [Google Scholar] [CrossRef]
  60. Hu, C.; Small, M.; Schadt, M. Reactive Ion Etching of AI(Cu) Alloys. MRS Online Proceeding Libr. Arch. 1986, 76, 191–195. [Google Scholar] [CrossRef]
  61. Howard, B.J.; Wolterman, S.K.; Yoo, W.J.; Gittleman, B.; SteinbrÜchel, C.H. Reactive Ion Etching of Copper with SiCl4 and CCl2F2. MRS Online Proceeding Libr. Arch. 2011, 201, 129–133. [Google Scholar] [CrossRef]
  62. Jin, S.W.; Lee, Y.H.; Yeom, K.M.; Yun, J.; Park, H.; Jeong, Y.R.; Hong, S.Y.; Lee, G.; Oh, S.Y.; Lee, J.H.; et al. Highly Durable and Flexible Transparent Electrode for Flexible Optoelectronic Applications. ACS Appl. Mater. Interfaces 2018, 10, 30706–30715. [Google Scholar] [CrossRef]
  63. Leech, P.; Reeves, G. Reactive ion etching of quartz and glasses for microfabrication. Proc. SPIE 1999, 3680, 341281. [Google Scholar]
  64. Holland, A.; Leech, P.; Reeves, G. Reactive ion etching of organic polymers for application in waveguide trench molds. J. Mater. Sci. 2004, 39, 3505–3508. [Google Scholar] [CrossRef]
  65. Queste, S.; Courjon, E.; Ulliac, G.; Salut, R.; Petrini, V.; Rauch, J.; Besançon Cedex, F. Deep Reactive Ion Etching of quartz, lithium niobate and lead titanate. JNTE Proc. 2008, 1, 1–2. [Google Scholar]
  66. Zhang, C.; Yang, C.; Ding, D. Deep reactive ion etching of PMMA. Appl. Surf. Sci. 2004, 227, 139. [Google Scholar] [CrossRef]
  67. Chapellier, P.; Lavenus, P.; Bourgeteau-Verlhac, B.; Gageant, C.; Le Traon, O.; Dulmet, B. Aspect ratio dependent etching in advanced deep reactive ion etching of quartz. In Proceedings of the 2017 Symposium on Design, Test, Integration and Packaging of MEMS/MOEMS (DTIP), Bordeaux, France, 29 May–1 June 2017; pp. 1–6. [Google Scholar]
  68. Zhong, Y.; Yuen, M. Hard mold UV nanoimprint lithography process. In Proceedings of the 2012 14th International Conference on Electronic Materials and Packaging (EMAP), Hong Kong, China, 13–16 December 2012; pp. 1–5. [Google Scholar]
  69. Nanoimprint Lithography (NIL)-SmartNIL®. Available online: https://www.evgroup.com/technologies/nanoimprint-lithography-smartnil/ (accessed on 26 May 2021).
  70. Fukuhara, M.; Ono, H.; Hirasawa, T.; Otaguchi, M.; Sakai, N.; Mizuno, J.; Shoji, S. UV Nanoimprint Lithography and Its Application for Nanodevices. J. Photopolym. Sci. Technol. 2007, 20, 549–554. [Google Scholar] [CrossRef]
  71. Hashmi, S. Reference Module in Materials Science and Materials Engineering; Elsevier: Oxford, UK, 2016; pp. 1–8. [Google Scholar]
  72. Kawaguchi, Y.; Nonaka, F.; Sanada, Y. Fluorinated materials for UV nanoimprint lithography. Microelectron. Eng. 2007, 84, 973–976. [Google Scholar] [CrossRef]
  73. Jianyun, H.; Changsong, Z.; Fan, Y.; Jinghui, Z.; Jinge, T.; Weimin, Y. UV-Curable micro-imprinting method for the fabrication of microstructure arrays. Microsyst. Technol. 2019, 25, 3311–3316. [Google Scholar] [CrossRef]
  74. Wang, M. Lithography; IntechOpen: London, UK, 2010; pp. 457–494. [Google Scholar]
  75. Tang, A.; He, S.; Lee, M. Fabrication of III–V compound nanowires via hot embossing nanoimprint lithography. Jpn. J. Appl. Phys. 2016, 55, 035001. [Google Scholar] [CrossRef]
  76. Chen, Y. Applications of nanoimprint lithography/hot embossing: A review. Appl. Phys. A 2015, 121, 451–465. [Google Scholar] [CrossRef]
  77. Roos, N.; Luxbacher, T.; Glinsner, T.; Pfeiffer, K.; Schulz, H.; Scheer, H.C. Nanoimprint lithography with a commercial 4-in. bond system for hot embossing. Proc. SPIE 2001, 4343, 427–435. [Google Scholar]
  78. Shiriaev, P.P.; Ryzhenko, D.S.; Makeev, M.O. Simulation of transparent electromagnetic interference shielding materials based on periodic conductive networks. J. Phys. Conf. Series. IOP Publ. 2019, 1410, 012206. [Google Scholar] [CrossRef]
  79. Shiriaev, P.; Makeev, M.; Ryzhenko, D.; Popkov, O. Theoretical study of electromagnetic and optical properties of periodic conductive networks based on Voronoi diagrams. Mater. Today Proc. 2019, 19, 2179–2182. [Google Scholar] [CrossRef]
  80. Vansovskaya, K.M. Metal coatings applied by chemical method. Mashinostroenie 1985, 2, 81–85. [Google Scholar]
  81. Shalkauskas, M.I.; Vashkialis, A.I. Chemical Metallization of Plastics, 3rd ed.; Chimia: Saint-Petersburg, Russia, 1985; pp. 137–142. [Google Scholar]
  82. Shi, Y.; Li, Y.; Zhang, J.; Yu, Z.; Yang, D. Electrospun polyacrylonitrile nanofibers loaded with silver nanoparticles by silver mirror reaction. Mater. Sci. Eng. C 2015, 51, 346–355. [Google Scholar] [CrossRef]
Materials 14 07178 g001 550
Figure 1. Design of a transparent acousto-optic modulator.
Figure 1. Design of a transparent acousto-optic modulator.
Materials 14 07178 g001
Materials 14 07178 g002 550
Figure 2. Technological limitations of various approaches to the formation of ordered mesh structures.
Figure 2. Technological limitations of various approaches to the formation of ordered mesh structures.
Materials 14 07178 g002
Materials 14 07178 g003 550
Figure 3. The topological figure of a conductive mesh.
Figure 3. The topological figure of a conductive mesh.
Materials 14 07178 g003
Materials 14 07178 g004 550
Figure 4. Technological process of micro-mesh formation.
Figure 4. Technological process of micro-mesh formation.
Materials 14 07178 g004
Materials 14 07178 g005 550
Figure 5. Photo of the manufactured sample.
Figure 5. Photo of the manufactured sample.
Materials 14 07178 g005
Materials 14 07178 g006 550
Figure 6. SEM images of the sample after the lithography and plasma chemical etching processes: (a) 2500× magnification; (b) 8000× magnification.
Figure 6. SEM images of the sample after the lithography and plasma chemical etching processes: (a) 2500× magnification; (b) 8000× magnification.
Materials 14 07178 g006
Materials 14 07178 g007 550
Figure 7. SEM images of the sample after metallization: (a) 1000×, (b) 4500×, (c) 7000×, and (d) 7000× magnification.
Figure 7. SEM images of the sample after metallization: (a) 1000×, (b) 4500×, (c) 7000×, and (d) 7000× magnification.
Materials 14 07178 g007
Materials 14 07178 g008 550
Figure 8. Sheet resistance distribution (a) and frequency dependence of the shielding efficiency (b) of the test sample.
Figure 8. Sheet resistance distribution (a) and frequency dependence of the shielding efficiency (b) of the test sample.
Materials 14 07178 g008
Materials 14 07178 g009 550
Figure 9. Photo of measuring equipment (a) and transmission spectrum of the test sample in the visible wavelength range (b).
Figure 9. Photo of measuring equipment (a) and transmission spectrum of the test sample in the visible wavelength range (b).
Materials 14 07178 g009
Materials 14 07178 g010 550
Figure 10. SEM images of the Si sample with grooves formed in its surface using the Bosch process with a high aspect ratio.
Figure 10. SEM images of the Si sample with grooves formed in its surface using the Bosch process with a high aspect ratio.
Materials 14 07178 g010
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Osipkov, A.; Makeev, M.; Konopleva, E.; Kudrina, N.; Gorobinskiy, L.; Mikhalev, P.; Ryzhenko, D.; Yurkov, G. Optically Transparent and Highly Conductive Electrodes for Acousto-Optical Devices. Materials 2021, 14, 7178. https://doi.org/10.3390/ma14237178

AMA Style

Osipkov A, Makeev M, Konopleva E, Kudrina N, Gorobinskiy L, Mikhalev P, Ryzhenko D, Yurkov G. Optically Transparent and Highly Conductive Electrodes for Acousto-Optical Devices. Materials. 2021; 14(23):7178. https://doi.org/10.3390/ma14237178

Chicago/Turabian Style

Osipkov, Alexey, Mstislav Makeev, Elizaveta Konopleva, Natalia Kudrina, Leonid Gorobinskiy, Pavel Mikhalev, Dmitriy Ryzhenko, and Gleb Yurkov. 2021. "Optically Transparent and Highly Conductive Electrodes for Acousto-Optical Devices" Materials 14, no. 23: 7178. https://doi.org/10.3390/ma14237178

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop