JP2017028059A - Photoelectric conversion element array - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a photoelectric conversion element array in which it is not indispensable to provide a filter of different characteristics for each photoelectric conversion element.SOLUTION: Each photoelectric conversion element 10 includes an active layer 40 on which conversion object light impinges. The active layer 40 of each photoelectric conversion element 10 contains a plasmonic material, causing plasmon resonance by interaction with the conversion object light. A first photoelectric conversion element and a second photoelectric conversion element are included in the plurality of photoelectric conversion elements 10. The resonance wavelength of plasmon resonance generated in a first active layer, i.e., the active layer 40 of the first photoelectric conversion element, is differentiated from the resonance wavelength of plasmon resonance generated in a second active layer, i.e., the active layer 40 of the second photoelectric conversion element.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a photoelectric conversion element array in which a plurality of photoelectric conversion elements are two-dimensionally arranged.

  What was described in Unexamined-Japanese-Patent No. 2013-165216 (patent document 1) is known as a photoelectric conversion element array. In the configuration described in Patent Document 1, a photoelectric conversion element array is used as an imaging element. Here, the plurality of photoelectric conversion elements constituting the photoelectric conversion element array have the same wavelength distribution of photoelectric conversion efficiency. Therefore, a color image is obtained by providing a different color filter (a color filter corresponding to any of blue, green, and red) for each photoelectric conversion element on the light incident side with respect to the photoelectric conversion element.

  As described above, in the configuration described in Patent Document 1, in order to obtain an image reflecting the spectrum (spectral distribution) of incident light like a color image, a filter having different characteristics for each photoelectric conversion element is provided. It is essential to provide it. In addition, since the wavelength distribution of photoelectric conversion efficiency is the same among all the photoelectric conversion elements, characteristics (bandwidth and the like) required for each filter tend to be severe. Therefore, when trying to reduce the pixel size determined according to the size of the photoelectric conversion element, there is a problem that the lower limit value is easily limited by the presence of the filter. In addition, there is a problem in that the sensitivity can be lowered as the transmittance of incident light is reduced by the filter.

JP2013-165216A

  Therefore, it is desired to realize a photoelectric conversion element array in which it is not essential to provide a filter having different characteristics for each photoelectric conversion element.

  In view of the above, the characteristic configuration of the photoelectric conversion element array in which a plurality of photoelectric conversion elements are two-dimensionally arranged is that each of the photoelectric conversion elements receives light to be converted which is light to be subjected to photoelectric conversion. An active layer, and each active layer of the photoelectric conversion element includes a plasmonic material that is a material in which plasmon resonance is generated by interaction with the light to be converted. A photoelectric conversion element and a second photoelectric conversion element are included, the resonance wavelength of plasmon resonance generated in the first active layer that is the active layer of the first photoelectric conversion element, and the active layer of the second photoelectric conversion element The resonance wavelength of plasmon resonance generated in the second active layer is different from each other.

In the plasmon resonance type photoelectric conversion element that converts light energy into electric energy using plasmon resonance as described above, the peak wavelength of the photoelectric conversion efficiency substantially coincides with the resonance wavelength of plasmon resonance generated in the active layer. Therefore, the wavelength distribution of the photoelectric conversion efficiency can be obtained by making the resonance wavelength of the plasmon resonance generated in the first active layer and the resonance wavelength of the plasmon resonance generated in the second active layer different from each other as in the above characteristic configuration. Can be different from each other between the first photoelectric conversion element and the second photoelectric conversion element. That is, the photoelectric conversion element itself can have wavelength selectivity for light absorption. As a result, even if a filter having different characteristics is not provided for each photoelectric conversion element, the electric signal generated by each of the plurality of photoelectric conversion elements constituting the photoelectric conversion element array can be used to generate incident light such as a color image. It is possible to obtain an image in which spectrum information is reflected.
As described above, according to the above characteristic configuration, it is possible to realize a photoelectric conversion element array in which it is not essential to provide filters having different characteristics for each photoelectric conversion element.

It is the schematic which shows an example of the cross-sectional structure of the photoelectric conversion element which concerns on embodiment. It is a flowchart which shows an example of the manufacturing method of the photoelectric conversion element which concerns on embodiment. It is a figure which shows an example of the measurement result of the wavelength dependence of the photoelectric conversion efficiency of the photoelectric conversion element which concerns on embodiment. It is the schematic of an example of the photoelectric conversion element which concerns on embodiment. It is the schematic of an example of the photoelectric conversion element array which concerns on embodiment. It is a figure which shows an example of the wavelength dependence of the photoelectric conversion efficiency of each photoelectric conversion element which comprises the photoelectric conversion element array which concerns on embodiment. It is the schematic which shows an example of the cross-section of the photoelectric conversion element which concerns on other embodiment. It is the schematic which shows an example of the cross-section of the photoelectric conversion element which concerns on other embodiment.

  An embodiment of a photoelectric conversion element array will be described with reference to the drawings. Here, as the photoelectric conversion element, the photoelectric conversion element includes three photoelectric conversion elements (first photoelectric conversion element, different plasmon resonance resonance wavelengths (hereinafter referred to as “plasmon resonance wavelengths”) generated in the active layer. A case where the second photoelectric conversion element and the third photoelectric conversion element are provided will be described as an example. 1, 4, 7, and 8 referred to in the following description, the ratio of the thickness (width in the vertical direction in the figure) of each layer constituting the photoelectric conversion element is not necessarily the actual ratio. It is not reflected in. 1, 4, 7, and 8, the cross-sectional structure (layer configuration) of the photoelectric conversion element is simplified. For example, in this embodiment, the plasmonic layer 40a is a layer containing a plurality of fine particles (nanoparticles), but in FIG. Both non-plasmonic layers 40b are shown as simplified uniform layers of uniform thickness. In the following, the direction in which the layers constituting the photoelectric conversion element are stacked, that is, the vertical direction in FIGS. 1, 4, 7, and 8 is referred to as “stacking direction”.

  As shown in FIG. 5, the photoelectric conversion element array 1 is formed by two-dimensionally arranging a plurality of photoelectric conversion elements 10. The plurality of photoelectric conversion elements 10 are two-dimensionally arranged along a plane orthogonal to the stacking direction. 5 illustrates a case where the outer shape of the photoelectric conversion element 10 in the stacking direction is square, and the plurality of photoelectric conversion elements 10 are arranged in a square lattice shape in the stacking direction. The outer shape of the photoelectric conversion element 10 when viewed in the stacking direction may be a shape other than a square (for example, a rectangle, a polygon other than a rectangle, a circle, or the like). Moreover, the arrangement of the plurality of photoelectric conversion elements 10 in the stacking direction view can be a lattice shape other than the square lattice (for example, a rectangular lattice shape, a hexagonal lattice shape, or the like). In the present embodiment, the photoelectric conversion element array 1 is used for an image sensor (image sensor), and one photoelectric conversion element 10 corresponds to one pixel. Although details are omitted, the imaging device includes, for example, a lens array in which a plurality of lenses are two-dimensionally arranged on the incident side of the conversion target light with respect to the photoelectric conversion element array 1. In this case, the light condensed by the corresponding lens is incident on each of the photoelectric conversion elements 10.

Each of the photoelectric conversion elements 10 has a function of converting light energy into electric energy. As shown in FIG. 1, each of the photoelectric conversion elements 10 includes an active layer 40 on which conversion target light, which is photoelectric conversion target light, is incident. FIG. 1 shows an example in which the active layer 40 is directly supported by the support substrate 70. 4 and 8 show an example in which the active layer 40 is supported indirectly by the support substrates 71 and 72 (that is, via another layer therebetween). Examples of the support substrates 70, 71, 72 include Si substrates, glass substrates (for example, quartz glass substrates), and TiO ₂ single crystal substrates. The TiO ₂ single crystal substrate is, for example, a TiO ₂ single crystal substrate doped with Nb.

  Each active layer 40 of the photoelectric conversion element 10 includes a plasmonic material that is a material in which plasmon resonance occurs due to interaction with light to be converted. In the present embodiment, the photoelectric conversion element array 1 is used as an imaging element for visible light. Therefore, in this embodiment, the conversion target light is light in the wavelength region of visible light. As the plasmonic material, for example, a metal, a metal nitride, or a metal oxide can be used. Examples of the metal used as the plasmonic material include Au, Ag, Al, Cu, Pt, and Pd. TiN can be exemplified as the metal nitride used as the plasmonic material. Examples of the metal oxide used as the plasmonic material include ITO (Indium tin oxide), FTO (Fluorine-doped tin oxide), and ZnO doped with other elements (such as aluminum and gallium). Hereinafter, ZnO doped with ITO, FTO, and other elements may be collectively referred to as “transparent conductive material”. As the plasmonic material, it is also possible to use a composite material obtained by combining a plurality of types of materials. The thickness of the active layer 40 is, for example, a value within a range in which a part of the conversion target light reaches the end of the conversion target light on the active layer 40, in other words, a part of the conversion target light is active. The value is set within a range that transmits through the layer 40. The thickness of the active layer 40 is, for example, a thickness included in a range of 400 nm or less. In the example shown in FIG. 1, the upper side in the figure is the incident side of the conversion target light with respect to the active layer 40, and the lower side in the figure is the outgoing side of the conversion target light (the incident side of the conversion target light and the incident side of the conversion target light). Is the opposite side). In the structure shown in FIG. 1, when the conversion target light is incident on the active layer 40 from the lower side in the drawing, a substrate having transparency with respect to the conversion target light is used as the support substrate 70. And good. “Transparency with respect to light to be converted” will be described later.

  When light having a wavelength capable of generating localized surface plasmon resonance in the active layer 40 is incident on the active layer 40, light is absorbed or scattered by the localized surface plasmon resonance. Assuming that the wavelength at which the absorbance is maximum in the wavelength range of light capable of generating localized surface plasmon resonance in the active layer 40 (the peak wavelength of the absorbance spectrum) is the plasmon resonance wavelength, the plasmon resonance wavelength is the plasmonic resonance wavelength of the plasmonic material. Types, shapes of structures formed of plasmonic materials (plasmonic particles in this embodiment as will be described later), dimensions of structures formed of plasmonic materials, and structures formed of plasmonic materials It is possible to control by the separation distance. For example, as the particle size of plasmonic particles decreases, the plasmon resonance wavelength generally shifts by a short wavelength. For example, as the shape of the plasmonic particle approaches a sphere, the plasmon resonance wavelength generally shifts by a short wavelength.

  The photoelectric conversion element 10 converts the light energy of the light to be converted into electrical energy using surface plasmon resonance (particularly localized surface plasmon resonance) generated in the active layer 40. Specifically, electric energy is generated by causing electron movement between the active layer 40 and a medium around the active layer 40 due to absorption of the conversion target light in the active layer 40. By enhancing the interaction between the conversion target light incident on the active layer 40 and the plasmonic material included in the active layer 40, the ratio of the conversion target light absorbed in the active layer 40 is increased and the photoelectric conversion efficiency is improved. Can be planned.

In this embodiment, as shown in FIG. 1, the active layer 40 is a layer having a structure (stacked body) in which plasmonic layers 40a and non-plasmonic layers 40b are alternately stacked in the stacking direction. Here, the plasmonic layer 40a is a layer formed using a plasmonic material, and the non-plasmonic layer 40b is a layer formed using a material (non-plasmonic material) different from the plasmonic material. is there. Unlike the case where the active layer 40 has only a single plasmonic layer 40a by making the active layer 40 a layer having a structure in which plasmonic layers 40a and non-plasmonic layers 40b are alternately stacked, By utilizing the surface plasmon coupling effect between the different plasmonic layers 40a, it is possible to improve the rate at which the conversion target light is absorbed in the active layer 40. As the non-plasmonic material, for example, a metal oxide can be used. Examples of the metal oxide used as the non-plasmonic material include TiO ₂ , ZnO, SnO ₂ , and SrTiO ₃ . For example, TiO ₂ is preferably used as the non-plasmonic material.

  The thickness of each of the plasmonic layer 40a and the non-plasmonic layer 40b can be, for example, a thickness included in a range of 1 nm to 5 nm. As will be described later, in the present embodiment, the plasmonic layer 40a is a layer including a plurality of plasmonic particles, and the thickness of the plasmonic layer 40a depends on the position in the plane orthogonal to the stacking direction. Can be different. In this case, the thickness of the plasmonic layer 40a can be defined as, for example, the average value or the maximum value of the thickness at each position in the plane orthogonal to the stacking direction. When the sum of the numbers of the plasmonic layer 40a and the non-plasmonic layer 40b constituting the active layer 40 is the number of stacked layers, the number of stacked layers is, for example, that part of the conversion target light is converted into the conversion target light in the active layer 40 It is set to a value within a range reaching the end on the emission side. The number of stacked layers is set to a value included in a range of 20 or less, for example. In the present embodiment, as shown in FIG. 1, the lowermost layer (the layer closest to the conversion target light emission side) constituting the active layer 40 is the plasmonic layer 40 a and also constitutes the active layer 40. The uppermost layer of the laminate (the layer on the most incident side of the conversion target light) is also the plasmonic layer 40a. Therefore, in this embodiment, the number of stacked layers is an odd number. In the example shown in FIG. 1, the number of stacked layers is “15”.

  In the present embodiment, the plasmonic layer 40a is a layer containing a plurality of plasmonic particles in order to increase the interaction between the light to be converted and the plasmonic material included in the active layer 40. Here, the plasmonic particles are fine particles containing a plasmonic material, and are, for example, fine particles made of a plasmonic material. The particle size of the plasmonic particles is, for example, a particle size of nanometer order (1 nm to 100 nm) or a submicron order (100 nm to 1 μm). In the present embodiment, the plurality of plasmonic particles included in the plasmonic layer 40a are two-dimensionally distributed and arranged along a plane orthogonal to the stacking direction. The arrangement of the plurality of plasmonic particles along the surface may be regular or irregular. The plurality of plasmonic particles are basically arranged apart from each other. The plasmonic layer 40a may be formed by using both a plasmonic material and a non-plasmonic material. For example, the plasmonic layer 40a may be formed on the whole or a part of the gap between the plasmonic particles in the plasmonic layer 40a. A configuration in which a monic material exists or a configuration in which plasmonic particles are covered with a non-plasmonic material can be employed.

  Next, a method for manufacturing the photoelectric conversion element according to this embodiment will be described. As shown in FIG. 2, the photoelectric conversion element manufacturing method according to the present embodiment includes a plasmonic material deposition process (step # 01, step # 03), a non-plasmonic material deposition process (step # 02), and an annealing process. (Step # 04). In the present embodiment, after the plasmonic material deposition process (step # 01) is performed, the non-plasmonic material deposition process (step # 02) is repeatedly executed n times, and then the plasmonic material deposition process (step # 01) is performed. # 03) and the annealing step (step # 04) are performed in the order described. The value of “n” is the value of the integer part of half the number of layers described above (half the value obtained by subtracting “1” from the number of layers).

  The plasmonic material deposition step (step # 01, step # 03) is a step of forming a plasmonic layer 40a by depositing a plasmonic material. The plasmonic material deposition step is, for example, a step of depositing plasmonic material by sputtering. Note that the first plasmonic material deposition step (step # 01) is performed on the support substrate (support substrate 70 in the example shown in FIG. 1) or another layer supported by the support substrate (in the example shown in FIG. 4). The plasmonic material is deposited on the two electrodes 32), and the second and subsequent plasmonic material deposition steps (step # 01, step # 03) are the previous non-plasmonic material deposition step (step # 02). The plasmonic material is deposited on the non-plasmonic material deposited by (1). The non-plasmonic material deposition step (step # 02) is a step of depositing a non-plasmonic material to form the non-plasmonic layer 40b. The non-plasmonic material deposition step is, for example, a step of depositing a non-plasmonic material by sputtering. The annealing step (step # 04) is a step of changing the plasmonic layer 40a into a layer containing a plurality of plasmonic particles by annealing to form a thin film deposited by the plasmonic material deposition step.

FIG. 3 shows an example of the measurement result of photoelectric conversion efficiency of the photoelectric conversion element 10 manufactured according to the procedure shown in FIG. 2, that is, IPCE (Incident Photon to Current Conversion Efficiency). FIG. 3 shows that in this example, the peak wavelength of the photoelectric conversion efficiency is approximately 650 nm. The peak wavelength of the photoelectric conversion efficiency substantially coincides with the plasmon resonance wavelength. Note that the photoelectric conversion element 10 used in this measurement was manufactured using a TiO ₂ single crystal substrate as the support substrate 70, using Au as the plasmonic material, and using TiO ₂ as the non-plasmonic material. In this production, the thickness of one layer of the plasmonic layer 40a formed in the plasmonic material deposition process is 2 nm, and the thickness of one layer of the non-plasmonic layer 40b formed in the non-plasmonic material deposition process is 3 nm. Then, the active layer 40 having a stacking number of “15” (n = 7) was formed. Thereafter, as an annealing step, annealing treatment in an argon atmosphere was performed at 800 ° C. for 1 hour to change the plasmonic layer 40a into a layer containing a plurality of plasmonic particles.

  The electrical energy generated by each of the photoelectric conversion elements 10 constituting the photoelectric conversion element array 1 is read out as an electric signal (voltage signal or current signal) by the reading circuit 2. The readout circuit 2 is, for example, a circuit similar to a readout circuit for a CCD (Charge Coupled Device) image sensor or a circuit similar to a readout circuit for a CMOS (Complementary Metal Oxide Semiconductor) image sensor. FIG. 4 shows an example of the structure of the photoelectric conversion element 10 including the electrode 30 for connection to an external circuit (in this example, the readout circuit 2). As shown in FIG. 4, the photoelectric conversion element 10 includes a pair of electrodes 30 including a first electrode 31 and a second electrode 32. In the example shown in FIG. 4, the insulating layer 4 is formed on the surface of the support substrate 71, and the second electrode 32, the active layer 40, and the transparent conductive material are formed on the wiring layer 3 formed so as to be exposed on the surface of the insulating layer 4. The body layer 81 is laminated in the order described. A first electrode 31 is formed on the upper surface of the transparent conductor layer 81. The first electrode 31 is formed only in a part of the upper surface of the transparent conductor layer 81, and most of the upper surface of the transparent conductor layer 81 is not covered with the first electrode 31.

The electrode 30 is formed using a conductive material. As a material (electrode forming material) for forming the electrode 30, for example, a metal or a metal oxide can be used. Examples of the metal used as the electrode forming material include Au, Ag, Cu, Pt, and Pd. Moreover, ITO and FTO can be illustrated as a metal oxide used as an electrode formation material. As an electrode forming material (for example, a material for forming the second electrode 32), TiO ₂ doped with a Group 5 element (Nb or the like), or a metal oxide such as TiO _{2 -X} or the like whose conductivity is improved by oxygen deficiency. May be used. In the example shown in FIG. 4, the transparent conductor layer 81 may also have the function of the first electrode 31.

In the example shown in FIG. 4, the transparent conductor layer 81 has transparency to the conversion target light in addition to the conductivity, and the conversion target light passes through the transparent conductor layer 81 and enters the active layer 40. . As a material for forming the transparent conductor layer 81, for example, a transparent conductive material such as ITO or FTO, or a p-type transparent conductive material such as NiO, CuAlO ₂ , LaCuOS, LaCuOSe, or SrCu ₂ O ₂ can be used. . In the structure shown in FIG. 4, the direction of electron movement induced inside the photoelectric conversion element 10 when the light to be converted enters the active layer 40 is, for example, the direction from the active layer 40 toward the second electrode 32. Become. A potential difference is generated between the first electrode 31 and the second electrode 32 as the electrons move inside the photoelectric conversion element 10, and a voltage signal or a current signal having a magnitude corresponding to the potential difference is detected by the readout circuit 2. .

  As shown in FIG. 5, the plurality of photoelectric conversion elements 10 constituting the photoelectric conversion element array 1 include a first photoelectric conversion element 11 and a second photoelectric conversion element 12. The first photoelectric conversion element 11 and the second photoelectric conversion element 12 have different plasmon resonance wavelengths. That is, the resonance wavelength of plasmon resonance generated in the active layer 40 of the first photoelectric conversion element 11 (hereinafter referred to as “first active layer”) and the active layer 40 of the second photoelectric conversion element 12 (hereinafter referred to as “second active layer”). The resonance wavelength of the plasmon resonance generated in the “active layer” is different from each other. For example, the type of plasmonic material, the shape of a structure formed by the plasmonic material (plasmonic particles in the present embodiment, the same applies hereinafter), the dimensions of the structure formed by the plasmonic material, and the plasmonic material The first active layer and the second active layer are made different from each other in at least one of the separation distances between the structures formed by the plasmon resonance resonance wavelength generated in the first active layer, The resonance wavelength of the plasmon resonance generated in the two active layers can be made different from each other. In addition, when supplementing about the above-mentioned “type of plasmonic material”, when the plasmonic material is a composite material in which a plurality of materials are combined, if the blending ratio of each material is different between the two plasmonic materials, These two plasmonic materials are assumed to have different material types.

  In the present embodiment, as shown in FIG. 5, the plurality of photoelectric conversion elements 10 constituting the photoelectric conversion element array 1 include a third photoelectric conversion element in addition to the first photoelectric conversion element 11 and the second photoelectric conversion element 12. 13 is included. The third photoelectric conversion element 13 has a plasmon resonance wavelength different from that of the first photoelectric conversion element 11 and the second photoelectric conversion element 12. That is, the resonance wavelength of the plasmon resonance generated in the active layer 40 (hereinafter referred to as “third active layer”) of the third photoelectric conversion element 13 is the resonance wavelength of the plasmon resonance generated in the first active layer and the second activity. This is different from the resonance wavelength of the plasmon resonance generated in the layer. For example, the type of plasmonic material, the shape of the structure formed by the plasmonic material, the dimension of the structure formed by the plasmonic material, and the separation distance between the structures formed by the plasmonic material By causing at least one of the first active layer, the second active layer, and the third active layer to be different from each other, the resonance wavelength of plasmon resonance generated in the first active layer and the second active layer are generated. The resonance wavelength of the plasmon resonance and the resonance wavelength of the plasmon resonance generated in the third active layer can be made different from each other.

  The peak wavelength of the photoelectric conversion efficiency of the photoelectric conversion element 10 substantially matches the plasmon resonance wavelength of the photoelectric conversion element 10 (the plasmon resonance resonance wavelength generated in the active layer 40 of the photoelectric conversion element 10). In addition to the peak whose wavelength substantially coincides with the plasmon resonance wavelength of the photoelectric conversion element 10, another peak may appear in the wavelength distribution of the photoelectric conversion efficiency of the photoelectric conversion element 10. In such a case, the peak wavelength that approximately matches the plasmon resonance wavelength among the plurality of peak wavelengths is set as the peak wavelength of the photoelectric conversion efficiency here.

  As described above, the plasmon resonance wavelengths of the first photoelectric conversion element 11, the second photoelectric conversion element 12, and the third photoelectric conversion element 13 are different from each other. Therefore, the peak wavelength of the photoelectric conversion efficiency of the first photoelectric conversion element 11 is set as the first peak wavelength, the peak wavelength of the photoelectric conversion efficiency of the second photoelectric conversion element 12 is set as the second peak wavelength, and the photoelectric conversion of the third photoelectric conversion element 13 is performed. When the peak wavelength of the conversion efficiency is the third peak wavelength, the first peak wavelength, the second peak wavelength, and the third peak wavelength are different from each other.

  In the present embodiment, the first photoelectric conversion element 11, the second photoelectric conversion element 12, so that all of the first peak wavelength, the second peak wavelength, and the third peak wavelength are included in the wavelength region of visible light. And the plasmon resonance wavelength of each of the 3rd photoelectric conversion elements 13 is determined. Specifically, as schematically shown in FIG. 6, the first peak wavelength corresponds to blue (450 nm in the example of FIG. 6), and the second peak wavelength corresponds to green (in the example of FIG. 6). 530 nm), and the third peak wavelength is a wavelength corresponding to red (600 nm in the example of FIG. 6), the first photoelectric conversion element 11, the second photoelectric conversion element 12, and the third photoelectric conversion element 13 respectively. The plasmon resonance wavelength is determined. By setting each peak wavelength in this way, a color image can be obtained using the photoelectric conversion element array 1.

  When the wavelength distribution of the photoelectric conversion efficiency is the same among all the photoelectric conversion elements, different color filters (blue, green) are provided on the incident side of the conversion target light with respect to the photoelectric conversion elements. And a color filter corresponding to any one of red). On the other hand, in the photoelectric conversion element array 1 according to the present embodiment, the first peak wavelength, the second peak wavelength, and the third peak wavelength are different from each other. Therefore, different color filters are used for each photoelectric conversion element. Even if it is not provided, a color image can be obtained. Therefore, it is not always necessary to provide a different color filter for each photoelectric conversion element. For example, such a color filter may not be provided. In this case, compared to the case where a different color filter is provided for each photoelectric conversion element, it becomes easier to reduce the pixel size, and the sensitivity is improved by the amount of absorption or scattering of light to be converted by the color filter. It is also possible to make it. Note that a filter for cutting off light that is not subject to photoelectric conversion (in this embodiment, infrared light or ultraviolet light) may be provided on the incident side of the light to be converted with respect to the photoelectric conversion element 10. Even in this case, by using a filter having a common characteristic for all the photoelectric conversion elements 10, the manufacturing process can be simplified as compared with the case where a filter having a different characteristic is provided for each photoelectric conversion element. There is an advantage that can be.

  In the example shown in FIG. 5, the number of pixels corresponding to green is twice the number of pixels corresponding to blue and the number of pixels corresponding to red, as in the Bayer array which is one of the color filter array methods. The number of second photoelectric conversion elements 12 is twice the number of first photoelectric conversion elements 11 and the number of third photoelectric conversion elements 13. That is, in the example shown in FIG. 5, a plurality of sets are regularly arranged with 2 × 2 4 pixels as one set. Then, when considering a quadrangle having apexes of four pixels constituting one set, the second photoelectric conversion element 12 is arranged in each of the pixels corresponding to the two apexes connected by the diagonal lines, and the remaining 2 The first photoelectric conversion element 11 and the third photoelectric conversion element 13 are arranged in two pixels corresponding to one vertex.

For example, in the plasmonic material deposition step (step # 01, step # 03 in FIG. 2), a plasmonic layer 40a having a thickness of 2 nm is formed using Au as the plasmonic material, and the non-plasmonic material deposition is performed. In the process (step # 02 in FIG. 2), a non-plasmonic layer 40b having a thickness of 2.5 nm is formed using TiO ₂ as a non-plasmonic material, and an annealing process (step # 04 in FIG. 2). Then, by performing annealing treatment in an argon atmosphere at 800 ° C. for 1 hour, the photoelectric conversion element 10 having a peak wavelength of photoelectric conversion efficiency corresponding to red (about 600 nm) can be manufactured. Moreover, the photoelectric conversion element 10 in which the peak wavelength of the photoelectric conversion efficiency is a wavelength corresponding to blue (about 450 nm) can be manufactured by performing the same processes as described above except that Ag is used as the plasmonic material. it can. Further, in the plasmonic material deposition process, a plasmonic layer 40a having a thickness of 1 nm is formed using Au as the plasmonic material, and TiO ₂ is used as the non-plasmonic material in the non-plasmonic material deposition process. The non-plasmonic layer 40b having a thickness of 2.5 nm is formed, and the annealing process in an argon atmosphere is performed at 900 ° C. for 2 hours or more in the annealing step, so that the peak wavelength of photoelectric conversion efficiency is green. The photoelectric conversion element 10 having a wavelength corresponding to (about 530 nm) can be manufactured.

  The peak wavelength of the photoelectric conversion efficiency is adjusted by using another material (for example, Al) as the plasmonic material, changing the thickness of the plasmonic layer 40a, changing the annealing temperature or annealing time, etc. May be. Specifically, as the thickness of the plasmonic layer 40a is reduced, the particle size of the formed plasmonic particles is reduced, and as a result, the peak wavelength of the photoelectric conversion efficiency is shifted to the short wavelength side. Further, as the annealing temperature and annealing time are increased, the shape of the formed plasmonic particles becomes closer to a sphere, and as a result, the peak wavelength of photoelectric conversion efficiency shifts to the short wavelength side. In addition, plasmonic particles may be formed using a fine processing technique such as nanoimprinting or electron beam drawing.

[Other Embodiments]
Other embodiments of the photoelectric conversion element array will be described. Note that the configurations disclosed in the following embodiments can be applied in combination with the configurations disclosed in other embodiments as long as no contradiction arises.

(1) In said embodiment, the photoelectric conversion element array 1 is equipped with the 1st photoelectric conversion element 11, the 2nd photoelectric conversion element 12, and the 3rd photoelectric conversion element 13, ie, the photoelectric conversion element array 1 is equipped. A configuration in which there are three types of photoelectric conversion elements 10 having different plasmon resonance wavelengths is described. However, the present invention is not limited to such a configuration, and the photoelectric conversion device array 1 may have two, four, or more types of photoelectric conversion devices 10 having different plasmon resonance wavelengths. For example, the photoelectric conversion element array can be configured to include a first photoelectric conversion element, a second photoelectric conversion element, a third photoelectric conversion element, and a fourth photoelectric conversion element that have different plasmon resonance wavelengths. In this case, for example, the peak wavelength of the photoelectric conversion efficiency of the first photoelectric conversion element is a wavelength corresponding to cyan, the peak wavelength of the photoelectric conversion efficiency of the second photoelectric conversion element is a wavelength corresponding to magenta, and the third photoelectric conversion element The first photoelectric conversion element, the second photoelectric conversion element, so that the peak wavelength of the photoelectric conversion efficiency is a wavelength corresponding to yellow, and the peak wavelength of the photoelectric conversion efficiency of the fourth photoelectric conversion element is a wavelength corresponding to green, It can be set as the structure by which each plasmon resonance wavelength of a 3rd photoelectric conversion element and a 4th photoelectric conversion element is set.

(2) In the above-described embodiment, the configuration in which the conversion target light is light in the visible wavelength region has been described as an example. However, without being limited to such a configuration, in addition to the light in the visible wavelength region, the light in the infrared wavelength region is also converted into the light to be converted, in addition to the light in the visible wavelength region A configuration in which light in the wavelength region of ultraviolet light is also converted into light, a configuration in which light in the wavelength region of infrared light and light in the wavelength region of ultraviolet light are also converted into light in addition to light in the wavelength region of visible light Can also be done. Alternatively, only light in the infrared wavelength region can be converted into light to be converted, or only light in the ultraviolet wavelength region can be converted into light to be converted.

(3) In the above embodiment, as illustrated in FIG. 4, the configuration in which the active layer 40 and the transparent conductor layer 81 are stacked in the order described on the upper surface of the second electrode 32 has been described as an example. However, without being limited to such a configuration, for example, as in the example shown in FIG. 7, the first intermediate layer 82, the active layer 40, the charge transfer layer 80, and the first electrode 32 are formed on the upper surface of the second electrode 32. The electrode 31 may be stacked in the order described. When the conversion target light passes through the first electrode 31 and the charge transfer layer 80 and is incident on the active layer 40, the first electrode 31 is made of a material having transparency to the conversion target light in addition to conductivity (for example, , A transparent conductive material such as ITO or FTO). Further, when the conversion target light passes through the second electrode 32 and the first intermediate layer 82 and enters the active layer 40, the second electrode 32 has transparency to the conversion target light in addition to conductivity. It is formed using a material. The second electrode 32 may be an electrode formed on a glass substrate. In addition, as a material for forming the second electrode 32, a material having good affinity with the first intermediate layer 82 is preferably used. For example, when the first intermediate layer 82 is formed using TiO ₂ , the material forming the second electrode 32 is preferably Ti.

The charge transfer layer 80 is a layer responsible for charge transfer between the first electrode 31 and the active layer 40 when light energy is converted into electrical energy. The charge transfer layer 80 is, for example, a layer containing an electrolyte containing a redox species (for example, a liquid electrolyte, a gel electrolyte, etc.) or a hole transport layer using a p-type semiconductor. As the redox species, for example, one or both of halogen and metal can be used. Examples of the halogen used as the redox species include Cl, Br, and I, and examples of the metal used as the redox species include Na, K, and Fe. Moreover, CuAlO ₂ and CuNbO can be exemplified as the p-type semiconductor used as the hole transport layer. For example, when the conversion target light passes through the first electrode 31 and the charge transfer layer 80 and enters the active layer 40, the charge transfer layer 80 needs to have transparency with respect to the conversion target light. Therefore, when the light to be converted passes through the first electrode 31 and the charge transfer layer 80 and is incident on the active layer 40 and the charge transfer layer 80 is a hole transport layer, the hole transport layer is, for example, CuAlO _2. Or a p-type semiconductor (p-type transparent conductive oxide) such as CuNbO.

The first intermediate layer 82 has semiconductor characteristics. Here, “having semiconductor characteristics” means that when the categories of “conductor”, “semiconductor”, and “insulator” are set in order from the side with higher conductivity according to the conductivity (electrical conductivity), Meaning having conductivity classified as "semiconductor". For example, it can be said that it has a semiconductor characteristic that electrical conductivity in normal temperature is contained in the range of 10 < ^-6 > S / m or more and 10 < ⁶ > S / m or less. Since the first intermediate layer 82 has semiconductor characteristics, movement of electrons in the first intermediate layer 82 for generating electric energy is enabled. When the conversion target light passes through the second electrode 32 and the first intermediate layer 82 and enters the active layer 40, the first intermediate layer 82 needs to have transparency with respect to the conversion target light. Here, “having transparency with respect to light to be converted” means that the transmittance with respect to light to be converted is 40% or more. Here, the transmittance is a transmittance at a wavelength at which the transmittance is highest in the wavelength range of the light to be converted. When the conversion target light passes through the second electrode 32 and the first intermediate layer 82 and enters the active layer 40, the transmittance of the first intermediate layer 82 with respect to the conversion target light may be 50% or more. Preferably, it is 60% or more. The thickness of the first intermediate layer 82 is, for example, a thickness included in the range of 10 nm to 500 μm.

As a material (first intermediate layer forming material) for forming the first intermediate layer 82, for example, a metal oxide (oxide semiconductor) or a conductive polymer (polymer semiconductor) can be used. Examples of the metal oxide used as the first intermediate layer forming material include TiO ₂ , ZnO, SnO ₂ , NiO, and VO ₂ . For example, TiO ₂ is preferably used as the first intermediate layer forming material. The metal oxide used as the first intermediate layer forming material may be a metal oxide whose conductivity is improved by doping with another element or oxygen deficiency. For example, TiO ₂ doped with a Group 5 element (Nb or the like) can be used as the first intermediate layer forming material. In this case, from the viewpoint of maintaining the semiconductor characteristics of the first intermediate layer 82, the content of the Group 5 element (Nb or the like) is preferably 1% by weight or less. For example, TiO _2-X having oxygen vacancies can be used as the first intermediate layer forming material. In this case, from the viewpoint of maintaining the semiconductor characteristics of the first intermediate layer 82, “X” of TiO _2-X is preferably set to 0.5 or less. As the first intermediate layer forming material, it is also possible to use a composite material in which a plurality of types of materials are combined.

  Further, as shown in FIG. 8, the reflective layer 60, the second intermediate layer 50, and the active layer 40 may be stacked on the support substrate 72 in the order described. In the configuration of FIG. 8, the upper side in the figure with respect to the active layer 40 is the incident side of the conversion target light. In other words, the photoelectric conversion element 10 is opposed to the active layer 40 with the second intermediate layer 50 disposed on the side opposite to the incident side of the conversion target light with respect to the active layer 40 and the second intermediate layer 50 interposed therebetween. And a reflective layer 60 arranged as described above. The second intermediate layer 50 corresponds to an “intermediate layer”.

  The second intermediate layer 50 has both semiconductor characteristics and transparency with respect to light to be converted. The transmittance of the second intermediate layer 50 with respect to the conversion target light is preferably 50% or more, and more preferably 60% or more. The thickness of the second intermediate layer 50 is, for example, a thickness included in the range of 10 nm to 500 μm. As a material (second intermediate layer forming material) for forming the second intermediate layer 50, for example, a metal oxide (oxide semiconductor) or a conductive polymer (polymer semiconductor) can be used. As the second intermediate layer forming material, for example, a material having transparency with respect to light to be converted among the above-described specific examples of the first intermediate layer forming material can be used.

  The reflective layer 60 has reflectivity for conversion target light. In the present embodiment, the reflective layer 60 is a flat layer. Here, “having reflectivity with respect to light to be converted” means that the reflectance with respect to light to be converted is 40% or more. The reflectance here is a reflectance at a wavelength at which the reflectance is highest in the wavelength range of the conversion target light. In addition, it is preferable that the reflectance with respect to the conversion object light of the reflection layer 60 is 60% or more, and it is still more preferable that it is 80% or more. The thickness of the reflective layer 60 is, for example, a thickness included in a range of 10 nm to several μm. As a material for forming the reflective layer 60 (reflective layer forming material), for example, metal or metal nitride can be used. Examples of the metal used as the reflective layer forming material include Au, Ag, Al, Cu, and Pt. Moreover, TiN can be illustrated as a metal nitride used as a reflective layer forming material. The reflective layer forming material may be the same material (for example, Au) as the plasmonic material included in the active layer 40. As the reflective layer forming material, a composite material in which a plurality of materials are combined can be used.

  In the configuration illustrated in FIG. 8, the photoelectric conversion element 10 includes a reflective layer 60 having reflectivity with respect to the conversion target light on the emission side of the conversion target light with respect to the active layer 40. And the 2nd intermediate | middle layer 50 arrange | positioned between the active layer 40 and the reflection layer 60 has transparency with respect to conversion object light. Therefore, the conversion target light transmitted through the active layer 40 can be reflected by the reflection layer 60 and incident again on the active layer 40, and the conversion target light and the plasmonic material included in the active layer 40 can be correspondingly increased. It is possible to strengthen the interaction. As a result, it is possible to improve the photoelectric conversion efficiency by increasing the rate at which the conversion target light is absorbed in the active layer 40. At this time, the intensity of light (reflected light) returning from the active layer 40 to the incident side of the light to be converted is reduced by appropriately setting the thickness of the second intermediate layer 50 in consideration of interference due to multiple reflection of light. Can be suppressed. As a result, it is possible to increase the rate at which the conversion target light transmitted through the active layer 40 is confined in the second intermediate layer 50 until it is absorbed in the active layer 40.

(4) In the above embodiment, the active layer 40 has been described as an example of a configuration having a structure (stacked body) in which the plasmonic layers 40a and the non-plasmonic layers 40b are alternately stacked. However, the configuration is not limited to such a configuration, and the active layer 40 may include only a single plasmonic layer 40a.

(5) In the above embodiment, the lowermost layer (the layer on the most emission side of the conversion target light) constituting the active layer 40 is the plasmonic layer 40a and the laminate constituting the active layer 40 The configuration in which the uppermost layer (the layer on the most incident side of the conversion target light) is also the plasmonic layer 40a has been described as an example. However, the present invention is not limited to such a configuration, and it is also possible to adopt a configuration in which one or both of the lowermost layer and the uppermost layer of the stacked body constituting the active layer 40 are non-plasmonic layers 40b.

(6) In the above embodiment, as an example, the thin film deposited by the plasmonic material deposition step is converted into particles by annealing, and the plasmonic layer 40a is changed to a layer containing a plurality of plasmonic particles. explained. However, without being limited to such a configuration, the plasmonic layer 40a including a plurality of plasmonic particles may be formed by a microfabrication technique, or plasmonics may be formed by arranging colloidal plasmonic particles. The layer 40a may be formed.

(7) In the above embodiment, the configuration in which the plasmonic layer 40a is a layer including a plurality of plasmonic particles has been described as an example. However, without being limited to such a configuration, for example, the plasmonic layer 40a may be a thin film layer formed using a plasmonic material.

(8) Regarding other configurations, it should be understood that the embodiments disclosed herein are merely examples in all respects. Accordingly, those skilled in the art can make various modifications as appropriate without departing from the spirit of the present disclosure.

[Overview of the above embodiment]
Hereinafter, an outline of the photoelectric conversion element array described above will be described.

  A photoelectric conversion element array (1) in which a plurality of photoelectric conversion elements (10) are two-dimensionally arranged, and each of the photoelectric conversion elements (10) receives light to be converted, which is light for photoelectric conversion. An active layer (40) that is incident is provided, and each active layer (40) of the photoelectric conversion element (10) includes a plasmonic material that is a material in which plasmon resonance occurs due to interaction with the light to be converted. The plurality of photoelectric conversion elements (10) include a first photoelectric conversion element (11) and a second photoelectric conversion element (12), and the active layer (40) of the first photoelectric conversion element (11). ) And the resonance wavelength of plasmon resonance generated in the second active layer which is the active layer (40) of the second photoelectric conversion element (12). Different There.

In the plasmon resonance type photoelectric conversion element (10) that converts light energy into electric energy using plasmon resonance as described above, the peak wavelength of photoelectric conversion efficiency is the resonance of plasmon resonance generated in the active layer (40). It almost coincides with the wavelength. Therefore, the wavelength distribution of the photoelectric conversion efficiency can be obtained by making the resonance wavelength of the plasmon resonance generated in the first active layer different from the resonance wavelength of the plasmon resonance generated in the second active layer as in the above configuration. The first photoelectric conversion element (11) and the second photoelectric conversion element (12) can be different from each other. That is, the photoelectric conversion element (10) itself can have wavelength selectivity for light absorption. As a result, even without providing filters with different characteristics for each photoelectric conversion element (10), using the electrical signals generated by each of the plurality of photoelectric conversion elements (10) constituting the photoelectric conversion element array (1), For example, it is possible to obtain an image reflecting information on the spectrum of incident light, such as a color image.
As described above, according to the above configuration, it is possible to realize the photoelectric conversion element array (1) in which it is not essential to provide filters having different characteristics for each photoelectric conversion element (10).

  Here, the kind of the plasmonic material, the shape of the structure formed by the plasmonic material, the dimensions of the structure formed by the plasmonic material, and the structures formed by the plasmonic material By making at least one of the separation distances different between the first active layer and the second active layer, the resonance wavelength of plasmon resonance generated in the first active layer, and the second active layer It is preferable that the generated plasmon resonances have different resonance wavelengths.

  According to this configuration, among the parameters that determine the resonance wavelength of the plasmon resonance, a parameter that is relatively easy to control is selected according to the structure of the active layer, and the resonance wavelength of the plasmon resonance generated in the first active layer The first photoelectric conversion element and the second photoelectric conversion element can be manufactured such that the plasmon resonance resonance wavelengths generated in the second active layer are different from each other.

  The plurality of photoelectric conversion elements (10) include a third photoelectric conversion element (13) in addition to the first photoelectric conversion element (11) and the second photoelectric conversion element (12). The resonance wavelength of the plasmon resonance generated in the active layer (40) of the three photoelectric conversion element (13) is the resonance wavelength of the plasmon resonance generated in the first active layer and the resonance of the plasmon resonance generated in the second active layer. Different from any of the wavelengths, the first peak wavelength which is the peak wavelength of the photoelectric conversion efficiency of the first photoelectric conversion element (11), and the peak wavelength of the photoelectric conversion efficiency of the second photoelectric conversion element (12). It is preferable that both the second peak wavelength and the third peak wavelength, which is the peak wavelength of the photoelectric conversion efficiency of the third photoelectric conversion element (13), are included in the visible light wavelength region.

  According to this configuration, by appropriately setting each of the first peak wavelength, the second peak wavelength, and the third peak wavelength, the plurality of photoelectric conversion elements (10) constituting the photoelectric conversion element array (1). A color image can be generated using the electrical signals generated by each.

  The active layer (40) includes a plasmonic layer (40a) formed using the plasmonic material, and a non-plasmonic layer (40b) formed using a material different from the plasmonic material. However, it is preferable to have a structure in which the layers are alternately stacked.

  According to this configuration, unlike the case where the active layer (40) has only a single plasmonic layer (40a), the surface plasmon coupling effect between different plasmonic layers (40a) is utilized. It becomes possible to increase the interaction between the light to be converted and the plasmonic material contained in the active layer (40). As a result, it is possible to improve the photoelectric conversion efficiency by increasing the rate at which the conversion target light is absorbed in the active layer (40).

  Each of the photoelectric conversion elements (10) includes an intermediate layer (50) disposed on a side opposite to the incident side of the conversion target light with respect to the active layer (40), and the intermediate layer (50). A reflective layer (60) disposed to face the active layer (40) across the substrate, the intermediate layer (50) having both semiconductor characteristics and transparency to the light to be converted The reflective layer (60) preferably has reflectivity for the conversion target light.

  According to this configuration, the reflective layer (60) having reflectivity with respect to the conversion target light is provided on the side opposite to the incident side of the conversion target light (that is, the emission side of the conversion target light) with respect to the active layer (40). The intermediate layer (50) provided and disposed between the active layer (40) and the reflective layer (60) has transparency to the light to be converted. Therefore, the conversion target light transmitted through the active layer (40) can be reflected by the reflective layer (60) and incident again on the active layer (40), and the conversion target light and the active layer (40) are correspondingly increased. It becomes possible to strengthen the interaction with the plasmonic material contained in the. That is, according to said structure, compared with the case where an intermediate | middle layer (50) and a reflection layer (60) are not provided, interaction with the plasmonic material contained in the light to be converted and an active layer (40) is strengthened. As a result, the ratio of the light to be converted absorbed in the active layer (40) can be increased to improve the photoelectric conversion efficiency. In addition, since the intermediate layer (50) has semiconductor characteristics in addition to transparency with respect to light to be converted, even when such an intermediate layer (50) is provided, the intermediate layer (50) is not Electron movement between the active layer (40) and the reflective layer (60) is allowed.

1: photoelectric conversion element array 10: photoelectric conversion element 11: first photoelectric conversion element 12: second photoelectric conversion element 13: third photoelectric conversion element 40: active layer 40a: plasmonic layer 40b: non-plasmonic layer 50: first Two intermediate layers (intermediate layers)
60: Reflective layer

Claims (5)

A photoelectric conversion element array in which a plurality of photoelectric conversion elements are two-dimensionally arranged,
Each of the photoelectric conversion elements includes an active layer on which conversion target light that is light of photoelectric conversion is incident,
Each of the active layers of the photoelectric conversion element includes a plasmonic material that is a material in which plasmon resonance occurs due to interaction with the light to be converted,
The plurality of photoelectric conversion elements include a first photoelectric conversion element and a second photoelectric conversion element,
Resonance wavelength of plasmon resonance generated in the first active layer that is the active layer of the first photoelectric conversion element and resonance wavelength of plasmon resonance generated in the second active layer that is the active layer of the second photoelectric conversion element Is a photoelectric conversion element array different from each other.   The kind of the plasmonic material, the shape of the structure formed by the plasmonic material, the size of the structure formed by the plasmonic material, and the separation distance between the structures formed by the plasmonic material By making at least one of them different between the first active layer and the second active layer, the resonance wavelength of plasmon resonance generated in the first active layer and the plasmon generated in the second active layer The photoelectric conversion element array according to claim 1, wherein resonance wavelengths of resonance are different from each other. The plurality of photoelectric conversion elements include a third photoelectric conversion element in addition to the first photoelectric conversion element and the second photoelectric conversion element,
The resonance wavelength of plasmon resonance generated in the active layer of the third photoelectric conversion element is either the resonance wavelength of plasmon resonance generated in the first active layer or the resonance wavelength of plasmon resonance generated in the second active layer. Are different,
The first peak wavelength which is the peak wavelength of the photoelectric conversion efficiency of the first photoelectric conversion element, the second peak wavelength which is the peak wavelength of the photoelectric conversion efficiency of the second photoelectric conversion element, and the photoelectric conversion of the third photoelectric conversion element 3. The photoelectric conversion element array according to claim 1, wherein all of the third peak wavelengths, which are efficiency peak wavelengths, are included in a visible light wavelength region.   The active layer has a structure in which a plasmonic layer formed using the plasmonic material and a non-plasmonic layer formed using a material different from the plasmonic material are alternately stacked. Item 4. The photoelectric conversion element array according to any one of Items 1 to 3. Each of the photoelectric conversion elements is disposed so as to face the active layer with an intermediate layer disposed on the side opposite to the incident side of the conversion target light with respect to the active layer and the intermediate layer interposed therebetween. A reflective layer;
The intermediate layer has both semiconductor characteristics and transparency to the light to be converted,
The photoelectric conversion element array according to claim 1, wherein the reflective layer has reflectivity with respect to the conversion target light.

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