Name: fabrication of nanopillar-based split ring resonators for displacement current mediated resonances in terahertz metamaterials
Uploaded: 2017-03-23T14:00:00
Description: Watch this Scientific Journal Video about Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials at JoVE.com

This material is based upon work supported by a start-up fund at the University of Minnesota, Twin Cities. Parts of this work were carried out in the Characterization Facility, University of Minnesota, a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org) via the MRSEC program. A portion of this work was also carried out in the Minnesota Nano Center which receives partial support from the NSF through the NNCI program.

Caution: Several of the chemicals used in these syntheses are toxic, highly flammable, and may cause irritation and severe organ damage when touched or inhaled. Please wear appropriate personal protective equipment (PPE) when handling.
1. Preparation of the First Layer of Gold (Au) Nanopillar Arrays (Figure 2a-c and Figure 2e-g)
<ol>
	<li>Preparation of Copper (Cu) Seed layers for Au electroplating (Figure 2a, b and Figure 2e, f)
	<ol>
		<li>Use a 4&#34; high resistivity silicon (Si) wafer (resi...

<ol>
	<li>Xu, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flexible+visible-infrared+metamaterials+and+their+applications+in+highly+sensitive+chemical+and+biological+sensing.">Flexible visible-infrared metamaterials and their applications in highly sensitive chemical and biological sensing.</a> Nano Lett. 11 (8), 3232-3238 (2011).</li><li>Singh, R., Cao, W., Al-Naib, I., Cong, L., Withayachumnankul, W., Zhang, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasensitive+terahertz+sensing+with+high-Q+Fano+resonances+in+metasurfaces.">Ultrasensitive terahertz sensing with high-Q Fano resonances in metasurfaces.</a> Appl. Phys. Lett. 105 (17), 171101 (2014).</li><li>Torun, H., Top, F. C., Dundar, G., Yalcinkaya, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+antenna-coupled+split-ring+resonator+for+biosensing.">An antenna-coupled split-ring resonator for biosensing.</a> J. Appl. Phys. 116 (12), 124701 (2014).</li><li>Chen, T., Li, S., Sun, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metamaterials+application+in+sensing.">Metamaterials application in sensing.</a> Sensors. 12 (3), 2742-2765 (2012).</li><li>Jaruwongrungsee, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic-based+Split-Ring-Resonator+Sensor+for+Real-time+and+Label-free+Biosensing.">Microfluidic-based Split-Ring-Resonator Sensor for Real-time and Label-free Biosensing.</a> Procedia Eng. 120, 163-166 (2015).</li><li>Han, J., Lakhtakia, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Semiconductor+split-ring+resonators+for+thermally+tunable+terahertz+metamaterials.">Semiconductor split-ring resonators for thermally tunable terahertz metamaterials.</a> J. Mod. Optic. 56 (4), 554-557 (2009).</li><li>Melik, R., Unal, E., Perkgoz, N. K., Puttlitz, C., Demir, H. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flexible+metamaterials+for+wireless+strain+sensing.">Flexible metamaterials for wireless strain sensing.</a> Appl. Phys. Lett. 95 (18), 181105 (2009).</li><li>Naqui, J., Dur&#225;n-Sindreu, M., Mart&#237;n, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alignment+and+position+sensors+based+on+split+ring+resonators.">Alignment and position sensors based on split ring resonators.</a> Sensors. 12 (9), 11790-11797 (2012).</li><li>Chiam, S., Singh, R., Gu, J., Han, J., Zhang, W., Bettiol, A. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increased+frequency+shifts+in+high+aspect+ratio+terahertz+split+ring+resonators.">Increased frequency shifts in high aspect ratio terahertz split ring resonators.</a> Appl. Phys. Lett. 94 (6), 064102 (2009).</li><li>Gil, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Varactor-loaded+split+ring+resonators+for+tunable+notch+filters+at+microwave+frequencies.">Varactor-loaded split ring resonators for tunable notch filters at microwave frequencies.</a> Electron. Lett. 40 (21), 1347-1348 (2004).</li><li>Driscoll, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tuned+permeability+in+terahertz+split-ring+resonators+for+devices+and+sensors.">Tuned permeability in terahertz split-ring resonators for devices and sensors.</a> Appl. Phys. Lett. 91 (6), 062511 (2007).</li><li>Liu, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Displacement+Current+Mediated+Resonances+in+Terahertz+Metamaterials.">Displacement Current Mediated Resonances in Terahertz Metamaterials.</a> Adv. Opt. Mater. 4 (8), 1302-1309 (2016).</li><li>Huang, M., Zhao, F., Cheng, Y., Xu, N., Xu, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large+area+uniform+nanostructures+fabricated+by+direct+femtosecond+laser+ablation.">Large area uniform nanostructures fabricated by direct femtosecond laser ablation.</a> Opt. Express. 16 (23), 19354-19365 (2008).</li><li>Broers, A., Molzen, W., Cuomo, J., Wittels, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electron-beam+fabrication+of+80-&#197;+metal+structures.">Electron-beam fabrication of 80-&#197; metal structures.</a> Appl. Phys. Lett. 29 (9), 596-598 (1976).</li><li>Isaacson, M., Muray, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insitu+vaporization+of+very+low+molecular+weight+resists+using+1/2+nm+diameter+electron+beams.">Insitu vaporization of very low molecular weight resists using 1/2 nm diameter electron beams.</a> J. Vac. Sci. Technol. 19 (4), 1117-1120 (1981).</li><li>Yang, J. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Understanding+of+hydrogen+silsesquioxane+electron+resist+for+sub-5-nm-half-pitch+lithography.">Understanding of hydrogen silsesquioxane electron resist for sub-5-nm-half-pitch lithography.</a> J. Vac. Sci. Technol. B. 27 (6), 2622-2627 (2009).</li><li>Duan, H., Yang, J. K., Berggren, K. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlled+Collapse+of+High-Aspect-Ratio+Nanostructures.">Controlled Collapse of High-Aspect-Ratio Nanostructures.</a> Small. 7 (18), 2661-2668 (2011).</li><li>Cord, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Limiting+factors+in+sub-10nm+scanning-electron-beam+lithography.">Limiting factors in sub-10nm scanning-electron-beam lithography.</a> J. Vac. Sci. Technol. B. 27 (6), 2616-2621 (2009).</li><li>Manfrinato, V. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Resolution+limits+of+electron-beam+lithography+toward+the+atomic+scale.">Resolution limits of electron-beam lithography toward the atomic scale.</a> Nano Lett. 13 (4), 1555-1558 (2013).</li><li>Ashraf, M., Sreenath, A., Chollet, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low-cost+mould+for+nano-imprinting+uses+monolayer+of+self-organized+nanospheres.">Low-cost mould for nano-imprinting uses monolayer of self-organized nanospheres.</a> SPIE Newsroom. , (2007).</li><li>Hu, T., Gao, Y., Wang, Z., Tang, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=One-dimensional+self-assembly+of+inorganic+nanoparticles.">One-dimensional self-assembly of inorganic nanoparticles.</a> Front. Phys. China. 4, 487-496 (2009).</li><li>Kitching, H., Shiers, M. J., Kenyon, A. J., Parkin, I. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Self-assembly+of+metallic+nanoparticles+into+one+dimensional+arrays.">Self-assembly of metallic nanoparticles into one dimensional arrays.</a> J. Mater. Chem. A. 1 (24), 6985-6999 (2013).</li><li>Klinkova, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+and+optical+properties+of+self-assembled+chains+of+plasmonic+nanocubes.">Structural and optical properties of self-assembled chains of plasmonic nanocubes.</a> Nano Lett. 14 (11), 6314-6321 (2014).</li><li>Caswell, K., Wilson, J. N., Bunz, U. H., Murphy, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preferential+end-to-end+assembly+of+gold+nanorods+by+biotin-streptavidin+connectors.">Preferential end-to-end assembly of gold nanorods by biotin-streptavidin connectors.</a> J. Am. Chem. Soc. 125 (46), 13914-13915 (2003).</li><li>Liu, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Step-growth+polymerization+of+inorganic+nanoparticles.">Step-growth polymerization of inorganic nanoparticles.</a> Science. 329 (5988), 197-200 (2010).</li><li>Nie, Z., Fava, D., Kumacheva, E., Zou, S., Walker, G. C., Rubinstein, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Self-assembly+of+metal-polymer+analogues+of+amphiphilic+triblock+copolymers.">Self-assembly of metal-polymer analogues of amphiphilic triblock copolymers.</a> Nat. Mater. 6 (8), 609-614 (2007).</li><li>Chen, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atomic+layer+lithography+of+wafer-scale+nanogap+arrays+for+extreme+confinement+of+electromagnetic+waves.">Atomic layer lithography of wafer-scale nanogap arrays for extreme confinement of electromagnetic waves.</a> Nat. Commun. 4 (2361), (2013).</li><li>Nam, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sub-10-nm+nanochannels+by+self-sealing+and+self-limiting+atomic+layer+deposition.">Sub-10-nm nanochannels by self-sealing and self-limiting atomic layer deposition.</a> Nano Lett. 10 (9), 3324-3329 (2010).</li></ol>

This fabrication technique has significant advantages for creating nano-scale structures over existing methods such as E-beam lithography and self-assembly. First, nano-scale structures can be realized over a large area (an entire wafer) using a photomask that features nanopillar arrays, which is not practical with an E-beam lithography process. Second, the fabrication process uses a traditional wafer scale micro fabrication process, which is much faster, simpler, and cheaper compared to E-beam lithography. Third, the at...

Terahertz (THz) metamaterials (MMs) have been developed for biomedical sensors and frequency-agile devices1,2,3,4,5,6,7,8,9,10,11. In order to improve the sensitivity and frequency selectivity of the THz MM sensors, a nanopillar-based split ring resonator (SRR) has been designed using displacement current generated inside gold (Au) nanopillar arrays to excite THz resonances with ultra-high quality factors (Q-factors) (~450) (Figure 1)12. Even though nanopillar-based SRRs show high Q-factors and promising sensing abilities, fabrication of such nanostructures with high aspect ratios (more than 40) and nano-scale gaps (sub-10 nm) over a large area remains challenging13.
The most commonly used technique to fabricate nano-scale structures is electron-beam lithography (EBL)14,15,16,17. However, the resolution of EBL is still limited due to the beam spot size, electron scattering, properties of the resist, and the development process18,19. In addition, it is not practical to fabricate nanostructures using EBL over a large area due to a slow process time and large process costs20. Another strategy to achieve nanostructures is to use a self-assembly technique21,22. By self-assembling metal nanocubes (NCs) in a solution and utilizing the electrostatic interaction and the association of polymer ligands between NCs, a well-organized one-dimensional NC array with nano-scale gaps can be achieved23. The nano-gap size depends on the polymer ligands between the NCs and can be controlled by applying different polymer materials with different molecular weights24,25,26. Self-assembly is a powerful technique for achieving scalable and cost-efficient nanostructures23. However, the fabrication process is more complicated compared to conventional micro and nano fabrication processes, and the control of nano-gap sizes is not precise enough for electronic device applications. In order to successfully fabricate nanopillar-based SRRs, a novel fabrication method should be invented to achieve the following goals: i) the fabrication process is easy to apply and is compatible with conventional micro and nano fabrication processes; ii) fabrication over a large area is applicable; iii) nano-gap sizes can be easily and precisely controlled with a 0.1 nm resolution and can be scaled down to 10 nm or less.
A novel fabrication method is demonstrated using the combination of an electroplating process and an atomic layer deposition (ALD) process to fabricate nanopillar-based SRRs. Since electroplating is a self-filling process with low cost, it is easy to fabricate structures over a large area. ALD is a chemical vapor deposition (CVD) process that can be precisely controlled by the reaction cycle during the process. The resolution of ALD thin film can be 0.1 nm, and the thin film is uniformly coated with a&#160;high quality, which is suitable to create nano-scale gaps27,28. Nanopillar-based SRR array with 10 nm gaps or less can be successfully fabricated over an area of 6 mm &#215; 6 mm. Both simulated and measured THz transmission spectra show resonant behaviors with ultra-high Q-factors and large frequency shifts, which proves the feasibility of the nanopillar-based SRRs mediated by displacement current. The detailed fabrication process is described below in the protocol section, and the video protocol can help practitioners to understand the fabrication process and avoid common mistakes associated with the fabrication of nanopillar-based SRRs.

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			<td height="21" style="height:21px;width:311px;">Silicon Wafer</td>
			<td style="width:295px;">Siltronic AG</td>
			<td style="width:199px;">N/A</td>
			<td style="width:437px;">100mm diameter, N-type, one-side polish, resitivity: 560-840 &#937;&#8226;cm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:311px;">Chromium</td>
			<td style="width:295px;">Kurt J. Lesker Company</td>
			<td style="width:199px;">EVMCR35J</td>
			<td>99.95% pure</td>
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			<td height="21" style="height:21px;width:311px;">Copper</td>
			<td style="width:295px;">Kurt J. Lesker Company</td>
			<td style="width:199px;">EVMCU40QXQJ</td>
			<td>99.99% pure</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:311px;">E-Beam Evaporator System</td>
			<td style="width:295px;">Rocky Mountain Vacuum Tech.</td>
			<td style="width:199px;">N/A</td>
			<td>RME-2000</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:311px;">S1813 Positive Photoresist</td>
			<td style="width:295px;">Microposit</td>
			<td style="width:199px;">10018348</td>
			<td>N/A</td>
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			<td height="21" style="height:21px;width:311px;">Spinner</td>
			<td style="width:295px;">Best Tools</td>
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			<td height="21" style="height:21px;width:311px;">Mask Aligner</td>
			<td style="width:295px;">Midas</td>
			<td style="width:199px;">MDA-400LJ</td>
			<td>N/A</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:311px;">Digital Hot Plate</td>
			<td style="width:295px;">Thermo Scientific</td>
			<td style="width:199px;">HP131725</td>
			<td>Super-Nuvoa series, maximum temperature: 370 degree C</td>
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			<td height="21" style="height:21px;width:311px;">MF319 Developer</td>
			<td style="width:295px;">Microposit</td>
			<td style="width:199px;">10018042</td>
			<td>N/A</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:311px;">Acetone</td>
			<td style="width:295px;">Fisher Chemical</td>
			<td style="width:199px;">A18P-4</td>
			<td style="width:437px;">N/A</td>
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			<td height="21" style="height:21px;width:311px;">Isopropyl Alcohol</td>
			<td style="width:295px;">Fisher Chemical</td>
			<td style="width:199px;">A416-4</td>
			<td>N/A</td>
		</tr>
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			<td height="21" style="height:21px;width:311px;">Gold 25 ES RTU</td>
			<td style="width:295px;">Technic Inc.</td>
			<td style="width:199px;">391427</td>
			<td>N/A</td>
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			<td height="21" style="height:21px;width:311px;">Source Meter</td>
			<td style="width:295px;">Keithley</td>
			<td style="width:199px;">N/A</td>
			<td>2612 System SourceMeter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:311px;">Microscope</td>
			<td style="width:295px;">Omax</td>
			<td style="width:199px;">NJF-120A</td>
			<td>N/A</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:311px;">Profilometer</td>
			<td style="width:295px;">Tencor Instruments</td>
			<td style="width:199px;">N/A</td>
			<td>Alpha-Step 200</td>
		</tr>
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			<td height="21" style="height:21px;width:311px;">APS Copper Etchant 100</td>
			<td style="width:295px;">Transfene Company, Inc.</td>
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			<td style="width:295px;">Transfene Company, Inc.</td>
			<td style="width:199px;">N/A</td>
			<td>N/A</td>
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			<td height="21" style="height:21px;width:311px;">Atomic Layer Deposition System</td>
			<td style="width:295px;">Cambridge Nano Tech inc.</td>
			<td style="width:199px;">N/A</td>
			<td>Savannah series</td>
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			<td height="21" style="height:21px;width:311px;">Ion Mill Etching System</td>
			<td style="width:295px;">Intlvac Thin Film</td>
			<td style="width:199px;">N/A</td>
			<td>Nanoquest series</td>
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			<td height="21" style="height:21px;width:311px;">Ultrasonic Cleaner</td>
			<td style="width:295px;">Crest Ultrasonics</td>
			<td style="width:199px;">N/A</td>
			<td>Powersonic series</td>
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			<td height="21" style="height:21px;width:311px;">Hydrofluoric Acid</td>
			<td style="width:295px;">Sigma-Aldrich</td>
			<td style="width:199px;">244279</td>
			<td>Diluted to 5%</td>
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			<td height="42" style="height:42px;width:311px;">Field Emission Gun Scanning Electron Microscope</td>
			<td style="width:295px;">Jeol Ltd.</td>
			<td style="width:199px;">N/A</td>
			<td>JEOL 6700 series</td>
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</table>

fabrication of nanopillar-based split ring resonators for displacement current mediated resonances in terahertz metamaterials

Terahertz (THz) split ring resonator (SRR) metamaterials (MMs) has been studied for gas, chemical, and biomolecular sensing applications because the SRR is not affected by environmental characteristics such as the temperature and pressure surrounding the resonator. Electromagnetic radiation in THz frequencies is biocompatible, which is a critical condition especially for the application of the biomolecular sensing. However, the quality factor (Q-factor) and frequency responses of traditional thin-film based split ring resonator (SRR) MMs are very low, which limits their sensitivities and selectivity as sensors. In this work, novel nanopillar-based SRR MMs, utilizing displacement current, are designed to enhance the Q-factor up to 450, which is around 45 times higher than that of traditional thin-film-based MMs. In addition to the enhanced Q-factor, the nanopillar-based MMs induce a larger frequency shifts (17 times compared to the shift obtained by the traditional thin-film based MMs). Because of the significantly enhanced Q-factors and frequency shifts as well as the property of biocompatible radiation, the THz nanopillar-based SRR are ideal MMs for the development of biomolecular sensors with high sensitivity and selectivity without inducing damage or distortion to biomaterials. A novel fabrication process has been demonstrated to build the nanopillar-based SRRs for displacement current mediated THz MMs. A two-step gold (Au) electroplating process and an atomic layer deposition (ALD) process are used to create sub-10 nm scale gaps between Au nanopillars. Since the ALD process is a conformal coating process, a uniform aluminum oxide (Al2O3) layer with nanometer-scale thickness can be achieved. By sequentially electroplating another Au thin film to fill the spaces between Al2O3 and Au, a close-packed Au-Al2O3-Au structure with nano-scale Al2O3 gaps can be fabricated. The size of the nano-gaps can be well defined by precisely controlling the deposition cycles of the ALD process, which has an accuracy of 0.1 nm.

Fabrication schemes show each step (Figure 2a-x). Optical images (Figure 2y-ac) and scanning electron microscope (SEM) images (Figure 2ad-ag) were collected for the nanopillar-based SRRs at different fabrication steps. Animations (Figure 2a-c) illustrate the first layer of electroplated Au nanopillars and the second layer of electroplated Au films as well as the nano-gaps created between them. Figure 2d s...

Watch this Scientific Journal Video about Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials at JoVE.com

Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials

A protocol for the design and fabrication of a novel nanopillar-based split ring resonator (SRR) is presented.

Terahertz (THz) split ring resonator (SRR) metamaterials (MMs) has been studied for gas, chemical, and biomolecular sensing applications because the SRR ...

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Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1. They owe ...

Terahertz Microfluidic Sensing Using a Parallel-plate Waveguide Sensor

Refractive index (RI) sensing is a powerful noninvasive and label-free sensing technique for the identification, detection and monitoring of microfluidic ...

Microwave Photonics Systems Based on Whispering-gallery-mode Resonators

Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various ...

Design, Fabrication, and Experimental Characterization of Plasmonic Photoconductive Terahertz Emitters

In this video article we present a detailed demonstration of a highly efficient method for generating terahertz waves. Our technique is based on ...

Evaluating Plasmonic Transport in Current-carrying Silver Nanowires

Plasmonics is an emerging technology capable of simultaneously transporting a plasmonic signal and an electronic signal on the same information ...

Fabrication and Characterization of Superconducting Resonators

Superconducting microwave resonators are of interest for a wide range of applications, including for their use as microwave kinetic inductance detectors ...

Colloidal Synthesis of Nanopatch Antennas for Applications in Plasmonics and Nanophotonics

We present a method for colloidal synthesis of silver nanocubes and the use of these in combination with a smooth gold film, to fabricate plasmonic ...

Stimulated Stokes and Antistokes Raman Scattering in Microspherical Whispering Gallery Mode Resonators

Dielectric microspheres can confine light and sound for a length of time through high quality factor whispering gallery modes (WGM). Glass microspheres ...