JP5867810B2 - Vertically stacked plasmon metal disk array for capturing broadband light - Google Patents

Description

  The present invention relates to a vertically stacked plasmon metal (eg, Au) disk array for capturing broadband light utilizing surface plasmon resonance, and a method of making such a disk array.

  Photovoltaic (PV) cells for converting sunlight into electric power are one of the most promising options for solving the energy and environmental problems we are facing this century. In promoting the spread of Si solar cells, light in the spectral band of 600 to 1100 nm in the solar spectrum is particularly important from the viewpoint of energy conversion efficiency and silicon (Si) consumption, which are major problems to be considered. This is because, in the sunlight spectrum, Si absorbs less light in this spectral band. As well described in a recent paper by Atwater et al. (See Non-Patent Documents 1 and 2), conventional Si solar cells are 200-300 μm thick to capture light of wavelength 600-1100 nm. A Si thin film was required. On the other hand, the remaining part of the solar spectrum can be absorbed even through a Si film as thin as approximately 2 μm. In order to produce a high-efficiency solar cell at a low cost, a solar cell that requires a thick Si thin film is impractical.

  Methods for combining plasmonic metal nanostructures with solar cells to increase light absorption and minimize Si thickness have been extensively studied in the past few years (see Non-Patent Documents 1-6). The increase in light absorption by the metal nanostructure is induced by hybridization (binding) of “light” known as surface plasmon polariton and “collective vibration of free electrons on the metal surface”. Because this plasmon interaction is greatly influenced by dimensional resonance between the metal nanostructure and the specific wavelength of the excitation light, a single nanostructure with a specific shape, such as a sphere, disk, or rod, It has its own surface plasmon resonance wavelength (or surface plasmon resonance frequency). Thus, an object composed only of a single type of nanostructure (ie, a single shape, size, and material) is effective for capturing light having a wavelength in the vicinity of a single resonance wavelength. In general, an increase in light absorption is mainly observed at wavelengths longer than the resonance wavelength. Its spectral width is approximately 100 nm (see Non-Patent Documents 7-9).

  It is an object of the present invention to provide improved nanostructures using surface plasmon resonance that captures light in a wider wavelength range with higher incident light utilization efficiency than similar types of nanostructures, and a method for producing the same Is to provide.

In accordance with one aspect of the present invention, a stack of a plurality of different sized disks disposed on a substrate is provided. These discs are made of metal. Spaces are respectively arranged between two adjacent disks.
The metal disk may be selected from the group consisting of Au, Ag, Al, Cu, and Pt.
The space may be at least partially filled with an insulating material.
The insulating material may be a SiO _2.
One layer may be placed at each interface between the disk and the insulating material to increase the adhesion between them.
The layer may be composed of Cr.
The diameter of the disk may be 1 nm to 1000 nm.
The disc may have a thickness of 1 nm to 500 nm.
A separation distance between adjacent disks may be 1 nm to 500 nm.
In accordance with another aspect of the present invention, an array of a stack of discs of different sizes as shown above is provided.
This stack may be between 1 nm and 10,000 nm.
In accordance with another aspect of the present invention, a method is provided for making a stack of discs of different sizes by inserting spacers. This manufacturing method includes the following steps.
(A) placing a polymer film with one hole on the substrate;
(B) repeatedly depositing on the thin film until a predetermined number of the disks and spacers are sputtered by sputtering and / or vapor-depositing the disk material and the spacer material;
(C) The thin film is peeled off to leave a stack of discs of different sizes with spacers deposited in the holes.
The material of the disk may be a metal, and the material of the spacer may be an insulating material.
The metal may be selected from the group consisting of Au, Ag, Al, Cu, and Pt.
The insulating material may be a SiO _2.
The method further includes depositing a layer at each interface between the disk and the spacer and sputtering and / or evaporating other materials to increase adhesion between them. But you can.
The material of the disk may be Au, the material of the spacer may be SiO ₂ , and the other material may be Cr.
The method may further include depositing a hard mask material for subsequent ion milling.
The ion milling may be Ar ion milling.
The material of the hard mask may be Cr.
The method may further include the step of partially removing the spacer by isotropic etching.
The spacer can be made of SiO ₂ and the isometric etching can be a wet etching using diluted hydrofluoric acid.

  According to the present invention, it is possible to provide a highly efficient solar cell with a smaller amount of Si consumption. More specifically, the present invention realizes a light-enhancing material that can concentrate in an extremely thin area below the nanometer range. By incorporating the material of the present invention into a solar cell, for example, a highly efficient solar cell can be obtained while using a smaller amount of raw materials. Furthermore, the thickness of the solar cell using the material of the present invention can be reduced. Such devices tend to be flexible. A further advantage of the present invention is that it can provide a photoelectric device, such as a highly sensitive CCD device, by utilizing the light enhancement of the material according to the present invention.

(A) 3D finite difference time domain method for normalized absorption (dashed line), scattering (dotted line), and dissipation (solid line) cross sections in a single Au disk with diameters of 80, 140, and 200 nm and 20 nm As a result of simulation by (FDTD), (b) Corresponding result in vertically laminated Au disk having the same size and 20 nm thick SiO ₂ intermediate layer, (c) Incident light at wavelengths of 590 nm (left) and 820 nm (right) FDTD simulation results on the distribution of the square strength of the local electric field amplitude in a three-layer Au disk for The directions of incident light and polarized light are represented by a one-way arrow and a two-way arrow, respectively. (A) A schematic diagram of a fabrication process according to the present invention. Multiple layers of Cr, Au, and SiO ₂ were deposited onto the lithographically patterned array of polymer holes. After peeling, the metal residue remaining on the end face of the disk was ion milled by Ar plasma. Next, Cr on the top surface and SiO _{2 on the} disk periphery were etched with a wet chemical solution. (B)-(f) Diameter is (b) 250 (bottom) / 170 (intermediate) / 90 (top) nm, (c) 200/140/80 nm, (d) 180/110/40 nm, (e) SEM image of 160/90 / <10 nm tri-layer Au disk. (F) Low magnification image of FIG. The pitch of the Au disk is 1 μm. (A) A diagram showing the scattering intensity ratio of the three-layer Au disk array of FIG. 2 (f) in comparison with a bare Si wafer. The continuous thick line is a visual guide, and the inset shows the beam path for analyzing the scattering properties. (B) A diagram showing simulated scattering spectra for three-layer, two-layer, and single-layer discs on a Si substrate. All are values divided by the simulated scattering spectrum of a bare Si wafer. The specifications of the three-layer Au disk are the same as in FIG. The same component of a three-layer disc was used to model the other two nanostructures. That is, for a single layer Au disk, it is a bottom Au layer, and for a double layer disk, it is a lower SiO ₂ layer having two adjacent Au layers. (C) The figure which shows the absorption loss per unit volume with respect to incident light with a wavelength of 620 nm (top) and 890 nm (bottom). The directions of incident light and polarized light are represented by a one-way arrow and a two-way arrow, respectively. The left and right images show three-layer and single-layer Au disks on a Si substrate, respectively. The figure which shows the topography image of the 3 layer Au disk obtained from the atomic force microscope (AFM) of the tapping mode. The scale bars in the AFM image are 1 μm (left) and 200 nm (right). The figure which shows the process which produces the lamination | stacking of the Au disk of a different size arrange | positioned at right angles to three layers. Such a stack is easily generated by single electron beam lithography followed by sputtering deposition. Now, the spectral window for plasmon excitation is obtained by merging the individual spectral windows of the internal disks with close single resonant wavelengths into one broadband window that encompasses multiple resonant wavelengths. Expanding. The lower part of FIG. 5 shows a stack of various sizes produced by the process shown in the upper part of FIG.

  The present invention provides a simple structure that expands the spectral window for plasmon excitation from an adjacent single resonance wavelength to one that includes multiple resonance wavelengths. This is made by creating plasmon nanostructures composed of several discs made from metals that exhibit all kinds of plasmon resonance, including Au, Ag, Al, Cu, and Pt, and arranged slightly spaced apart Done. In the following, only Au is referred to as the plasmonic metal, but it should be noted that Au is merely a typical example of a plasmonic metal and can be replaced by any other plasmonic metal. In the present invention, it should be noted that the “disk” is not limited to a circular disk, and may have any shape. As far as the inventor knows, instead of adopting the commonly used two-dimensional form, the present invention arranges vertical stacks of Au disks of different sizes for broadband interaction with incident sunlight. It is new in that it has been. The present invention is illustrated without loss of generality by a specific stack with three Au disks.

A simulation result by a three-dimensional finite difference time domain method (FDTD) performed as a first step for evaluating the effect of stacking Au disks is shown. The tools and setup used for this simulation are described near the end of the specification. FIG. 1 (a) shows the normalized absorption (dashed line), scattering (dotted line), and dissipated (solid line) cross sections for single Au disks with diameters of 80, 140, and 200 nm and 20 nm thickness. As clearly seen by the sharp peaks shown in FIG. 1 (a), the plasmon interaction between the incident light and the single Au disk is limited to the vicinity of their resonant wavelength. In the present invention, by placing such single disks in close proximity to each other, the windows of each individual spectrum are merged into one broadband window. The inset in FIG. 1B illustrates a laminated Au multi-layer disc. The specifications of the individual internal disk are the same as the single disk shown in FIG. Adjacent disks are separated by spacers such as a 20 nm thick SiO ₂ interlayer. Materials other than SiO ₂ can also be used as spacers as long as they are transparent to light and have electrical insulating properties. The extinction curve of the three-layer Au disk of FIG. 1 (b) clearly shows three prominent peaks at wavelengths 580, 680 and 840 nm. Due to the near-field electromagnetic coupling of the closely stacked disks, the position of the three scattering peaks is slightly shifted to the red side from the initial position in the isolated single disk. For the same reason, two absorption peaks appear at wavelengths 580 and 820 nm. In the map of | E / E ₀ | ² shown in FIG. 1 (c), E ₀ and E represent the amplitudes of the incident electric field and the enhanced electric field, respectively, but this map is adjacent to the local enhanced electric field. It is shown that there is between Au disks. This may be useful for applications in plasmon enhancement sensors (see Non-Patent Documents 10-13). It will also be useful for applications in the generation of plasmon-assisted photocurrents by organic molecules (see Non-Patent Documents 14 and 15).

Plasmon coupling between Au disks can be adjusted by changing the space between adjacent disks. By increasing the thickness of the SiO ₂ layer, the coupling between the Au disks is gradually disconnected. Along with this, as shown in Table 1, both the intensity of the absorption peak and the shift of the scattering peak decrease. This table shows the position of the scattering peak in a three-layer Au disk having various intermediate SiO ₂ layers. The thickness of the intermediate SiO ₂ layer varied from 15 to 40 nm. The specifications of the Au disk itself have not been changed (diameter = 80 (top), 140 (intermediate), 200 (bottom) nm, all thickness = 20 nm). Table 1 is inserted to understand why the scattering peaks shift. This phenomenon can be used to adjust the spectral range in light absorption. Desirable ranges for disk diameter, disk thickness, and disk separation would be 1 nm to 1000 nm, 1 nm to 500 nm, and 1 nm to 500 nm, respectively.

  Based on such simulation results, the three-layer Au disk is expected to interact with light in a wider spectral band than a single disk. In addition, with respect to the area density of the metal nanostructures on the surface of the solar cell, the vertically stacked Au disk is more desirable than the disk dispersed in the lateral direction. This is because a shadowing problem occurs when too many metal nanostructures are provided on a solar cell (see Non-Patent Document 8).

In order to form a multi-layer Au nanostructure, the fabrication process shown in FIG. 2 (a) can be used. As shown in FIG. 2 (a), an overhang structure always develops around the patterned polymer hole in thin film deposition by sputtering process. This is because some of the sputtered atoms are scattered in the middle and enter from directions other than the vertical direction. For this reason, electron beam or thermal evaporation is generally used in metal stripping processes instead of sputtering processes. This is to maintain the original shape and size of the pattern formed by lithography. In the present invention, in order to form a vertical stack of Au disks having different sizes, continuous shrinkage of pattern forming holes by an overhang structure was intentionally employed. For this purpose, multiple layers of Au, SiO ₂ and Cr were deposited by sputtering, as shown in FIG. 2 (a). 20 nm thick Au and SiO ₂ were alternately deposited without vacuum break. In order to improve the adhesion of Au, a 2 nm thick Cr layer was also incorporated into each interface between the Au and SiO ₂ layers. Since Cr is known to degrade the optical properties of the metal nanostructure (see Non-Patent Documents 16 and 17), the thickness of the interface Cr was minimized. However, 10 nm thick Cr was deposited on the top surface. This is for use as a hard mask for subsequent Ar ion milling. This Ar ion milling is performed to remove metal residues remaining around the Au disk after sputtering deposition and further peeling. During sputtering deposition, metal residues are produced in the form of thin film deposition by scattering and surface diffusion in the vapor phase of the atoms deposited by sputtering. It extends beyond the patterned nominal diameter (see Non-Patent Documents 13 and 18). Details of this process are described near the end of the specification.

  Needless to say, the substrate shown in FIG. 2A is depicted as a simple substrate having no special structure, but this is merely for the sake of simplicity. If the Au disk stack of the present invention is applied to a solar cell, the substrate should have a structure suitable for the solar cell. If the Au disk stack is used for other purposes, the substrate will have a structure for such use. In addition, while in the above description a sputtering process is used to deposit the layer, other processes such as vapor deposition can be used as long as an overhang structure as shown in FIG. Can also be used instead of or in combination with the sputtering process.

Scanning electron microscope (SEM) images shown in FIGS. 2B to 2F are observed after Ar ion milling and further wet chemical etching of Cr and SiO ₂ . This image shows that a stepped and terraced three-layer Au disk was successfully produced. The periphery of the intermediate SiO ₂ is scraped off by etching using diluted hydrofluoric acid (HF) acid (1% aqueous solution). This is as confirmed by the fact that the end face of the Au disk appears clearly. However, as long as the sample is not etched for a long time (greater than 30 minutes), the central portion of SiO ₂ remains and maintains a predetermined separation between adjacent Au disks. It is believed that such partial etching of the intermediate SiO ₂ may be because the SiO ₂ layer is so thin that exposure to HF acid is limited and the etching rate is reduced.

  In addition, while FIG. 2 (a) shows only one disk, the low magnification SEM image shown in FIG. 2 (f) shows that an array of many vertically stacked disks is on one substrate. It shows where it is arranged. A preferred range of free space between the laminated disks is 0.1 to 10 times the lateral width of the laminated disks. In the specific example shown in FIG. 2 (c), the preferred space setting range is 20 nm to 2000 nm. More generally stated, a desirable space setting range is 1 nm to 10,000 nm.

As shown in FIG. 4, the topography data obtained from the atomic force microscope (AFM) shows that the steps in each layer are well matched with the total thickness of the Au, SiO ₂ , and Cr layers. Is shown. In the manufacturing process proposed here, the central axis of each internal disk is self-aligned. In this respect, it is very different from the general electron beam lithography process, which requires careful steps to align all substrate patterns.

Further, as shown in a series of SEM images in FIGS. 2B to 2E, the specifications of the Au nanostructure are changed, for example, insertion of an Si ₃ N ₄ antireflection layer into a Si solar cell, etc. It is possible to adapt the resonance frequency to changes in the surrounding dielectric conditions such as It can be done simply by adjusting the size of the resist holes that define the diameter of the bottom disk.

  In order to demonstrate the usefulness of a three-layer Au disk array for wide area interaction with incident light, the scattering spectrum obtained from the nanostructured sample shown in FIG. 2 (f) was analyzed. Scattering intensity was observed using a confocal microscope using a UV-NIR light source. As shown in the inset of FIG. 3A, the sample was mounted obliquely (approximately 30 °) with respect to the direction of the incident light in order to exclude excessively strong reflected light. In order to isolate the effect of the Au nanostructure, the scattering spectrum obtained from the three-layer Au disk array was weighted with the Au disk area ratio (about 4% of the total surface area) and then from the bare Si surface. Divided by the scattering spectrum. The result is as shown in FIG.

  First, FIG. 3 (a) clearly shows that stronger scattering is obtained over a wider wavelength range in Au nanostructures according to the present invention compared to bare Si. In addition, the three prominent peaks shown in FIG. 3 (a) correspond to the three maxima in the scattering spectrum from the simulation shown in FIG. 1 (b). However, there is a considerably large shift toward the red side because the Si substrate has a high index. The influence of the surrounding dielectric conditions was confirmed by another FDTD simulation that models an array of three-layer Au disks on a Si substrate (simulation details are given in the experimental section). As shown in FIG. 3 (b), the scattering curve obtained from the three-layered Au disk on the Si substrate is divided into three characteristics when divided by the scattering spectrum of the bare Si surface. It shows a peak. The position of such a peak is very close to the experimental data of FIG. The other two curves in FIG. 3 (b) represent the scattering spectra obtained by simulation for two-layer and single-layer Au disks on the Si substrate. It indicates that the number and position of the peaks are determined by the number and specifications of the internal Au disk. It is also noteworthy that the scattering intensity of the two-layer and three-layer discs is greatly improved compared to a single disc.

The residual differences between the experimental and simulation data seen in FIGS. 3 (a) and 3 (b) are probably due to the effects of residual Cr, metal surfaces roughened by the ion milling process, and inaccurate SiO ₂ content. It is believed that this is due to estimates. In the model of FDTD simulations it was assumed diameter of SiO ₂ is 45% of the diameter of the Au disk that is immediately above the said SiO ₂ layer. None of the possible effects of residual Cr and roughened surfaces were considered in the model. This is to limit complexity and reduce the number of excess tuning parameters.

  Finally, the measured and calculated scatter intensities shown in FIGS. 3 (a) and 3 (b) are both monitored in air and represent only a small portion of all scatter. It should be noted that This is because the photons scattered by the plasmon-type nanostructure are selectively redirected toward the high index substrate (see Non-Patent Documents 1 and 4). This is unquestionably advantageous for efficient absorption of light energy. As a visible example, a two-dimensional plot of absorption loss per unit volume is shown in FIG. This is calculated from the divergence of the pointing vector (see Non-Patent Document 19) and demonstrates that incident light is intensively absorbed into Si under the Au nanostructure. doing. Furthermore, since the multi-layer structure (the image on the left side of FIG. 3C) sends light to a larger range than the single-layer plasmon structure (the image on the right side of FIG. 3C), the light energy It is clear that it is more effective for absorption. This is also consistent with the scattering intensity discussed above in connection with FIG. 3 (b). Such a fact clearly points to the advantage of using a three-dimensional stacked plasmon structure over traditional two-dimensional patterns. Specific design elements, such as the area density and specifications of Au nanostructures, or the positions where they are placed in practical solar cells can be further optimized to collect light with high efficiency. Let's go.

An example of this fabrication process for making a three-layer Au disk by taking the simple steps of lithography and sputtering deposition is described below. Sputter deposition of multiple layers of Au / SiO ₂ and the structure that it is overhanging allows self-tuning of the diameter of the Au disk. It also enables self-alignment of their central axes. Compared to a single plasmon-type nanostructure, a three-layer Au disk exhibits a strong interaction with light having a broad spectral band. This has been verified by numerical electromagnetic simulation. It has also been verified by direct observation of relative scattering properties as shown in FIGS. In view of such results, the Au nanostructure according to the present invention is expected to be useful for high-efficiency Si solar cells through harvesting broadband light.

[Production of three-layer Au disk]
To make a bilayer resist stack, 100 nm thick polymethylglutarimide (PMGI, MicroChem) was spin coated onto a Si substrate and baked at 180 ° C. for 3 minutes. Next, a 50 nm thick resist called ZEP (ZEP520A, Nippon Zeon Co., Ltd.) was spin-coated on the PMGI and baked at 180 ° C. for 3 minutes. Electron beam exposure was performed with a beam acceleration voltage of 50 KeV. After this ZEP resist (ZED-N50, Nippon Zeon Co., Ltd.) was developed by a commercial development company, the sample was immersed in an aqueous alkaline solution (NMD-3, JSR Micro) for 5 seconds, where PMGI An undercut cross-sectional shape was formed. Then, 10 nm Cr (top) / to _{(20nm Au / 2nm Cr / 20nm} SiO 2 / 2nm Cr) x2 / 20nm Au / 2nm Cr plurality of layers having the structure of (bottom) is, on the template polymer that is patterned, Deposited by magnetron sputtering with a base pressure below 10 ⁻⁷ Pa. After peeling off in acetone and removing PMGI in NMD-3, the metal residue near the Au disk was etched with Ar plasma. Finally, the Cr layer and the SiO 2 layer were formed using a Cr etching solution (mixed solution of HClO ₄ and (NH ₄ ) ₂ [Ce (NO ₃ ) ₆ ]) and diluted hydrofluoric acid (1% HF aqueous solution). Chemically removed. The Au disk array fabricated on the Si substrate was confirmed with a scanning microscope (SU-8000, Hitachi) and a tapping mode atomic force microscope (L-tracell, Sill NanoTechnology Inc.).

[Analysis of scattering spectra]
The measurement of the scattering spectrum was performed using a confocal microscope (alpha300S, WItec), a UV-NIR light source (DH-2000-BAL, Ocean Optics), and a spectrometer (Acton SP2300, Princeton Instruments). The intensity of scattered light from the sample was accumulated for 1 second. This was repeated 120 times to obtain an average value.

[Electromagnetic simulation]
The electromagnetic simulation was performed using 3D finite difference time domain method software (Lumeral FDTD solution 6.5). For the absorption and scattering simulations shown in FIG. 1, the grid was set to a 1.0 nm cubic lattice. Perfectly matched layers (PML) were used as boundary conditions. Isolated nanostructures were placed in a uniform medium of air and irradiated from above using linearly polarized plane waves. A three-dimensional monitor box enclosing the Au nanostructure was used to calculate the scattering and absorption power. In order to calculate the absorption loss and scattering spectra from the Au nanostructure on the Si substrate shown in FIG. 3, the periodic boundary conditions were used in the lateral direction to model the array structure. PML conditions were used in the vertical direction. The same light source as the above model was used, and a two-dimensional monitor device for obtaining scattering power from the sample into the air was disposed 200 nm above the Si surface.

As described in detail, the vertical plasmon type disk stack of the present invention can be used in a wide variety of devices including, but not limited to:
(1) Flexible thin film type solar cell;
(2) a photoelectric device such as an image sensor using a CCD (charge-coupled device);
(3) A sensor based on SERS (surface enhanced Raman scattering);
(4) SEIRA (Surface-Enhanced Infrared Absorption) sensor.

H. A. Atwater, A .; Polman, Nat. Mater. 2010, 9, 205-213. V. E. Ferry, J. et al. N. Munday, H.M. A. Atwater, Adv. Mater. 2010, 22, 4794-4808. S. -S. Kim, S .; -L. Na, J. et al. Jo, D.C. -Y. Kim, Y .; -C. Nah, Appl. Phys. Lett. 2008, 93, 073307. K. R. Catchpole, A.M. Polman, Appl. Phys. Lett. 2008, 93, 19113. R. A. Pala, J.A. White, E .; Barnard, J .; Liu, M .; L. Brongersma, Adv. Mater. 2009, 21, 3504-3509. A. Aubury, D.C. Y. Lei, A .; I. Fernndez-Dom? nguez, Y.M. Sonnefrad, S.M. A. Maier, J .; B. Pendry, NanoLett. 2010, 10, 2574-2579. S. H. Urn, W .; Mar, P.M. Mathew, D.M. Derkacs, E .; T. T. et al. Yu, J .; Appl. Phys. 2007, 101, 14309. C. Rockstuhl, S.M. Fahr, F .; Lederer, J. et al. Appl. Phys. 2008, 104, 123102. C. Rockstuhl, F.M. Lederer, Appl. Phys. Lett. 2009, 94, 213102. J. et al. N. Anker, W.M. P. Hall, O .; Lyandres, N.M. C. Shah, J .; Zhao, R.A. P. Van Duyne, Nat. Mater. 2008, 7, 442-453. S. Nie, S .; R. Emory, Science 1997, 275, 1102-1106. J. et al. F. Li, Y. F. Huang, Y. et al. Ding, Z. L. Yang, S .; B. Li, X. S. Zhou, F.A. R. Fan, W.M. Zhang, Z .; Y. Zhou, D.C. Y. Wu, B.B. Ren, Z. L. Wang, Z .; Q. Tian, Nature 2010, 464, 392-395. J. et al. -S. Wi, E .; S. Barnarad, R.A. J. et al. Wilson, M.M. Zhang, M .; Tang, M.M. L. Brongersma, S .; X. Wang, ACS Nano 2011, 5, 6449-6457. M.M. D. Brown, T.W. Suthewong, R.A. S. S. Kumar, V .; Dlnnocenzo, A.D. Petrozza, M.M. M.M. Lee, U. Wiesner, H.C. J. et al. Snaith, Nano Lett. 2011, 11, 438-445. K. Ikeda, K .; Takahashi, T .; Masuda, K .; Uosaki, Angew. Chem. Int. Ed. 2011, 50, 1280-1284. X. Jiao, J .; Goeckeritz, S .; Blair, M.M. Oldham, Plasmonics 2009, 4, 37-50. H. Aouani, J. et al. Wenger, D.W. Gerard, H.C. Rigneault, E .; Devaux, T .; W. Ebesen, F.M. Mahdavi, T .; Xu, S .; Blair, ACS Nano 2009, 3, 2043-2048. W. Hu, R.A. J. et al. Wilson, L.M. Xu, S .; -J. Han, S .; X. Wang, J .; Vac. Sci. Technol. B 2007, 25, 1294-1297. http: // docs. luminous. com / en / fdtd / user_guide_loss_per_unit_volume. html

Claims (20)

A stack of disks having different surface plasmon resonance frequencies by having a plurality of different sizes, wherein the disks are arranged on a substrate, the disk is made of plasmon metal , and the disk size decreases as it moves away from the substrate And the substrate is stacked vertically, and the disks are stacked vertically with each other , and a spacer made of an insulating material is provided between adjacent pairs of the disks.   The stack of claim 1, wherein the plasmonic metal is selected from the group consisting of Au, Ag, Al, Cu, and Pt. The laminate according to claim 1, wherein the insulating material is SiO ₂ . 4. Laminate according to any of claims 1 to 3, wherein one layer is disposed at each interface between the disk and the spacer to increase the adhesion between them . The laminate according to claim 4 , wherein the layer is made of Cr . The lamination according to any one of claims 1 to 5, wherein the disk has a diameter of 1 nm to 1000 nm . The lamination according to any one of claims 1 to 6, wherein the disc has a thickness of 1 nm to 500 nm . The lamination according to any one of claims 1 to 7, wherein a separation distance between adjacent disks among the disks is 1 nm to 500 nm . 9. An array comprising a stack of the plurality of different sized disks according to any one of claims 1-8 . The array according to claim 9, wherein the stacking pitch is 1 nm to 10,000 nm . A method for producing a stack of disks made of a plurality of different sized plasmon metals by inserting spacers made of an insulating material and having different surface plasmon resonance frequencies by having the plurality of different sizes, comprising the following steps: Method.
(A) placing a polymer film with one hole on the substrate;
(B) Sputtering and / or evaporating the disk material and the spacer material until the predetermined number of disks and spacers are sputtered on the thin film and to the edge of the hole, and the hole. Repeatedly depositing on the substrate via;
(C) The thin film is peeled off, and a spacer is inserted to leave behind a stack of a plurality of discs of different sizes deposited in the holes. The method of claim 11, wherein the plasmonic metal is selected from the group consisting of Au, Ag, Al, Cu, and Pt . The method according to claim 11, wherein the insulating material is SiO ₂ . 12. The method further comprises depositing one layer at each interface between the disk and the spacer and sputtering and / or evaporating other materials to increase adhesion between them. 14. The method according to any one of 13 to 13 . The method of claim 14 , wherein the material of the disk is Au, the material of the spacer is SiO ₂ , and the other material is Cr . The method according to claim 11, further comprising depositing a hard mask material for subsequent ion milling . The method of claim 16 , wherein the ion milling is Ar ion milling . The method according to claim 16 or 17, wherein the material of the hard mask is Cr . The method according to claim 11, further comprising a step of partially removing the spacer by a method called isotropic etching . The spacer is made of SiO _2, the isotropic etching is a wet etching using hydrofluoric acid diluted method of claim 19.