Plasmon enhanced detector and manufacturing method thereof

Abstract

The invention discloses a plasmon enhanced detector and a manufacturing method thereof. The plasmon enhanced detector comprises a semiconductor substrate, a graphene layer, a metal particle array and an electrode group, the graphene layer is formed on the surface of the semiconductor substrate and exposes a part of the semiconductor substrate; the metal particle array is formed on the surface of the graphene layer; and the electrode group is arranged on the exposed surface of the semiconductor substrate and partially extends to the surface of the metal particle array. According to the plasmon enhanced detector, the strong coupling plasmon is combined with the graphene layer, so that the plasmon resonance performance of the metal nanoparticle structure is completely released, and the overall performance of the detector is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of detectors and semiconductor devices, and in particular to a plasmon-enhanced detector and a manufacturing method thereof. Background Art

[0002] Metal plasmon is a coupled resonance mode generated by the collective oscillation of incident electromagnetic waves and free electrons on the surface or inside metal nanoparticles, which can enhance the interaction between light and matter. It is a quasiparticle, and the electromagnetic field can be localized in the subwavelength range, resulting in the enhancement of light energy in the subwavelength range. Therefore, the metal plasmon effect is widely used in nonlinear optics, surface enhanced Raman and photoelectric sensing. Metal plasmons can be divided into surface plasmon resonance propagated on the surface and localized surface plasmon resonance localized around metal nanoparticles. The resonance characteristics of metal plasmons are related to the free electron concentration, mobility and carrier transition of the material. Metals are common plasmon materials, such as gold, silver, and aluminum, involving resonance frequencies ranging from near-infrared to ultraviolet wavelengths. Localized surface plasmons cannot propagate freely, and they usually gather around metal nanoparticles, causing the resonant electromagnetic field coupled to the metal nanoparticles to be strongly enhanced compared to the incident optical field. Therefore, the introduction of localized plasmon resonance effect in photodetectors can improve the light absorption efficiency of light detection materials, and the light scattering enhancement effect of metal nanoparticles can also enhance the light conversion efficiency of detection materials. The relevant characteristics have shown broad application prospects in LEDs and solar cells. In addition, photodetectors based on plasmon effects can not only enable us to further reduce the size of devices while breaking through the optical diffraction limit, but also provide an effective method to improve the photoelectric conversion efficiency in a specific wavelength region without sacrificing the detection response speed and bandwidth.

[0003] At present, a large number of research reports have used the metal plasmon effect to improve the detector structure based on semiconductor materials, emphasizing that the local electromagnetic field enhances absorption and scattering to cause the generation of additional electron-hole pairs, and using strong local electric fields to accelerate the separation of electron-hole pairs. YenTaJen et al. used the surface plasmon and supertransmission characteristics of Al nanohole arrays and metal aluminum as electrodes to improve carrier transport performance, and prepared a coupled ultraviolet enhanced detector with extremely high response rate and detection sensitivity. The above-mentioned use of metal nanohole arrays as electrodes and plasmon carriers to enhance the detection effect and reduce the carrier transport distance in the photoelectric conversion process, but the plasmon resonance performance of metal nanoholes is still subject to certain limitations.

[0004] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0005] In view of the deficiencies in the prior art, an object of the present invention is to provide a plasmon-enhanced detector and a method for manufacturing the same.

[0006] To achieve the above-mentioned objectives, an embodiment of the present invention provides a plasmon enhanced detector, comprising: a semiconductor substrate, a graphene layer, a metal particle array and an electrode group; the graphene layer is formed on the surface of the semiconductor substrate and exposes a portion of the semiconductor substrate; the metal particle array is formed on the surface of the graphene layer; the electrode group is arranged on the exposed surface of the semiconductor substrate and partially extends over the surface of the metal particle array.

[0007] In one or more embodiments of the present invention, the graphene layer is a single-layer graphene.

[0008] In one or more embodiments of the present invention, the electrode group includes a first electrode and a second electrode, the first electrode is formed on the exposed surface of the semiconductor substrate, and the second electrode extends from the surface of the semiconductor substrate to the surface of the metal particle array.

[0009] In one or more embodiments of the present invention, the first electrode and the second electrode are tooth electrodes, the first electrode has a first tooth group, the second electrode has a second tooth group, the first tooth group and the second tooth group are staggered and arranged opposite to each other, the second tooth group is arranged on the surface of the metal particle array, and the projection of the second tooth group in a direction perpendicular to the surface of the semiconductor substrate on which it is located completely falls into the graphene layer.

[0010] In one or more embodiments of the present invention, a Schottky contact is formed between the electrode group and the semiconductor substrate.

[0011] In one or more embodiments of the present invention, one of the electrode groups forms a Schottky contact with the semiconductor substrate, and the other electrode group forms an Ohmic contact with the semiconductor substrate.

[0012] In one or more embodiments of the present invention, the electrode group is selected from nickel / gold electrodes and / or titanium / gold electrodes.

[0013] In one or more embodiments of the present invention, the metal particle array includes a plurality of metal particles arranged in an array, and the metal particle array satisfies the following relationship: pd≦10nm, 10nm≦p≦100nm, 20nm≦d≦200nm, 20nm≦h≦90nm, wherein p is the periodic distance between the centers of any two adjacent metal particles, d is the diameter of each metal particle, and h is the thickness of each metal particle.

[0014] In one or more embodiments of the present invention, the material of the metal particles is selected from any one or a combination of two or more of aluminum, silver, zinc and gallium.

[0015] In one or more embodiments of the present invention, the material of the semiconductor substrate is selected from direct bandgap semiconductor materials.

[0016] An embodiment of the present invention provides a method for manufacturing the above-mentioned plasmon-enhanced detector, comprising:

[0017] forming a graphene layer on a surface of a semiconductor substrate;

[0018] forming an array of metal particles on the surface of the graphene layer;

[0019] An electrode group is formed on the surface of the semiconductor substrate and the surface of the metal particle array.

[0020] Compared with the prior art, the plasmon-enhanced detector according to the embodiment of the present invention is based on a strongly coupled metal particle array placed on a graphene layer structure. The single-layer graphene layer does not affect the coupling between the metal particle array and the semiconductor substrate, and the light transmittance of the single-layer graphene layer can be as high as 98%. Graphene has a strong carrier transport capability and can be used as a metal electrode. This structure uses the plasmon field enhancement effect of the metal particle array to improve the carrier generation and separation capabilities, and also uses the graphene layer to improve the carrier transport capability, thereby regulating the overall performance of the detector's photoelectric conversion process and achieving overall performance improvement of the detector.

[0021] The plasmon-enhanced detector according to the embodiment of the present invention fully considers the three steps of photoelectric conversion, optimizes the three steps, and thus improves the detector response. First, in the carrier generation process, the plasmon effect of the metal particle array enhances the absorption of the photosensitive area, and the scattering effect of the metal particle array allows more light to enter the semiconductor substrate; secondly, in the carrier separation process, the local electric field is conducive to the separation of electron-hole pairs, and hot carriers overcome the Schottky barrier to enter the semiconductor substrate, promoting the transport of carriers; thirdly, the strongly coupled metal particle array is placed on a single-layer graphene layer structure, and the single-layer graphene layer does not affect the coupling between the metal particle array and the semiconductor substrate. At the same time, the single-layer graphene layer has a transmittance of up to 98%, and at the same time, it acts as an electrode to improve the carrier transport characteristics and enhance the overall performance of the semiconductor detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a front view of a plasmon-enhanced detector according to an embodiment of the present invention;

[0023] Figure 2 is a cross-sectional view of a plasmon-enhanced detector according to an embodiment of the present invention.

[0024] Figure 3 is a process flow chart of manufacturing a plasmon-enhanced detector according to one embodiment of the present invention;

[0025] Figure 4a and Figure 4b Schematic diagram of the manufacturing process structure steps of a plasmon-enhanced detector according to one embodiment of the present invention; DETAILED DESCRIPTION

[0026] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0027] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0028] Generally speaking, the photoelectric conversion process based on semiconductor photodetectors is divided into three steps. First, the generation of carriers in the active area of ​​the device under the excitation of incident light; second, the separation process of carriers; third, the conversion of carrier transport into electrical signals. Therefore, based on plasmon-coupled detection devices, in addition to improving the device photoelectric detection response rate, how to further realize a detector with fast detection speed and high sensitivity is very important for improving the characteristics of the plasmon-coupled semiconductor photoelectric conversion process.

[0029] As mentioned in the background technology, a large number of research reports have used metal plasmon effects, such as metal nanoparticle structures such as gold, silver and aluminum, to improve the photoelectric detection performance of semiconductor materials such as zinc oxide and wide-bandgap nitrides. There are also literature reports that use the surface plasmon resonance effect and super-transmission characteristics of metal aluminum nanohole arrays to prepare aluminum gallium nitride ultraviolet detection devices with high detection responsiveness and high sensitivity. However, in the detector structure involved in the above-mentioned use of the plasmon resonance effect of metal nanoholes, the plasmon resonance performance of metal nanoholes is still subject to certain limitations.

[0030] In order to solve the above technical problems, the present invention proposes a plasmon-enhanced detector and a method for manufacturing the plasmon-enhanced detector, which fully releases the plasmon resonance performance of the metal nanoparticle structure by utilizing strongly coupled plasmons combined with a graphene layer, thereby improving the overall performance of the detector.

[0031] like Figure 1 and Figure 2As shown, a plasmon-enhanced detector according to an embodiment of the present invention includes: a semiconductor substrate 10, a graphene layer 20, a metal particle array 30 and an electrode group 40. The graphene layer 20 is formed on the surface of the semiconductor substrate 10 and exposes a portion of the semiconductor substrate 10. The metal particle array 30 is formed on the surface of the graphene layer 20. The electrode group 40 is arranged on the exposed surface of the semiconductor substrate 10 and partially extends on the surface of the metal particle array 30. The present invention improves the carrier generation and separation capabilities by utilizing the plasmon field enhancement effect of the metal particle array 30, and also utilizes the graphene layer 20 to improve the carrier transport capability, thereby regulating the overall performance of the detector's photoelectric conversion process and achieving overall performance improvement of the detector.

[0032] In a more specific implementation case, the material of the semiconductor substrate 10 is selected from direct bandgap semiconductor materials. Exemplary, for example: GaN, ZnO, Ga2O3, etc. The graphene layer 20 is a single layer of graphene. The single layer of graphene does not affect the coupling between the metal particle array 30 and the semiconductor substrate 10, and the light transmittance of the single layer of graphene can be as high as 98%. The metal particle array 30 can be a periodic metal particle array, and each layer of graphene layer 20 is provided with a metal particle array 30. Preferably, the metal particle array 30 includes a plurality of metal particles arranged in an array, and the metal particle array satisfies the following relationship: pd≦10nm, 10nm≦p≦100nm, 20nm≦d≦200nm, 20nm≦h≦90nm, wherein p is the periodic distance between the centers of any two adjacent metal particles, d is the diameter of each metal particle, and h is the thickness of each metal particle.

[0033] The plasmon effect of the metal particle array in the present invention can enhance the absorption of the photosensitive area of ​​the semiconductor substrate, and the scattering effect of the metal particle array allows more light to enter the semiconductor substrate, thereby improving the detection performance of the detector. The metal particle array is formed on the graphene layer, and the graphene layer is used to fully release the plasmon resonance performance of the metal particle array, thereby improving the overall performance of the detector.

[0034] In a more specific implementation case, the material of the metal particles is selected from any one or a combination of two or more of aluminum, silver, zinc and gallium, preferably metal aluminum particles, but not limited thereto. The shape of the metal particles includes any one or a combination of two or more of spheres, columns, pyramids and polyhedrons, etc., preferably columns, but not limited thereto.

[0035] The electrode group 40 includes a first electrode 41 and a second electrode 42 . The first electrode 41 is formed on the exposed surface of the semiconductor substrate 10 , and the second electrode 42 extends from the surface of the semiconductor substrate 10 to the surface of the metal particle array 30 .

[0036] In a more specific implementation case, the first electrode 41 and the second electrode 42 are both tooth electrodes, and the first electrode 41 includes a first connection electrode 412 and a first tooth group 411 connected to the first connection electrode 412, and the first tooth group 411 includes a plurality of first teeth arranged in parallel. The first connection electrode 412 is arranged on the same side of the plurality of first teeth. The second electrode 42 includes a second connection electrode 422 and a second tooth group 421 connected to the second connection electrode 422, and the second tooth group 421 includes a plurality of second teeth arranged in parallel. The second connection electrode 422 is arranged on the same side of the plurality of second teeth. The number of the second teeth is consistent with the number of the graphene layer 20. The number of the first teeth is consistent with the number of the second teeth. The first tooth group 411 and the second tooth group 421 are staggered and arranged opposite to each other. The second connection electrode 422 partially covers and connects the graphene layer 20. The second tooth group 421 is arranged on the surface of the metal particle array 30 located on the graphene layer 20, and the projection of the second tooth group 421 in a direction perpendicular to the surface of the semiconductor substrate 10 on which it is located falls completely into the graphene layer 20, that is, each second tooth in the second tooth group 421 has a size smaller than the size of the corresponding graphene layer 20.

[0037] In a more specific implementation case, a Schottky contact is formed between the electrode group 40 and the semiconductor substrate 10. In this case, the material of the electrode group is selected from nickel / gold. In another more specific implementation case, a Schottky contact is formed between one of the electrode groups 40 and the semiconductor substrate 10, and the material of the electrode group 40 is selected from nickel / gold; another of the electrode groups 40 forms an ohmic contact with the semiconductor substrate 10, and the material of the electrode group 40 is selected from titanium / gold.

[0038] like Figure 3 As shown, an embodiment of the present invention also provides a method for manufacturing the above-mentioned plasmon enhanced detector, including: s1: forming a graphene layer on the surface of a semiconductor substrate; s2: forming a metal particle array on the surface of the graphene layer; s3: forming an electrode group on the surface of the semiconductor substrate and the surface of the metal particle array.

[0039] The following is combined with Figure 4a-4b A schematic diagram of the manufacturing process structure steps of the plasmon enhanced detector is provided to further clearly and completely explain the technical solution of the present invention.

[0040] refer to Figure 4a As shown, a semiconductor substrate 10 is provided, wherein the material of the semiconductor substrate 10 is selected from direct bandgap semiconductor materials, such as GaN, ZnO, Ga2O3, etc. Graphene a is transferred or grown on the surface of the semiconductor substrate 10. The graphene a is a large-area single-layer graphene. The single-layer graphene layer does not affect the coupling between the metal particle array 30 and the semiconductor substrate 10, and the light transmittance of the single-layer graphene layer can be as high as 98%.

[0041] refer to Figure 4b As shown, glue is applied on the graphene a and ultraviolet lithography is performed, and the graphene in the area on the semiconductor substrate 10 that does not need to be covered by the graphene layer is etched away, leaving the graphene in the required area to form a graphene layer 20. In this embodiment, there are two graphene layers 20, and the two graphene layers 20 are arranged side by side. Each graphene layer 20 is preferably arranged as a rectangular structure. Glue is continued to be applied on the graphene layer 20 and ultraviolet lithography is performed to expose the area where the graphene layer 20 is located. Then, an anodic aluminum oxide (AAO) mask is transferred on the graphene layer 20; metal particles are grown by electron beam evaporation, preferably aluminum particles here, and the AAO mask is removed by high-temperature tape to obtain a metal particle array with a periodic structure-Al particle array.

[0042] Exemplarily, the metal particle array 30 may be a periodic metal particle array, and a metal particle array 30 is disposed on each graphene layer 20. Preferably, the metal particle array 30 includes a plurality of metal particles arranged in an array, and the metal particle array satisfies the following relationship: pd≦10nm, 10nm≦p≦100nm, 20nm≦d≦200nm, 20nm≦h≦90nm, wherein p is the periodic distance between the centers of any two adjacent metal particles, d is the diameter of each metal particle, and h is the thickness of each metal particle.

[0043] The plasmon effect of the metal particle array in the present invention can enhance the absorption of the photosensitive area of ​​the semiconductor substrate, and the scattering effect of the metal particle array allows more light to enter the semiconductor substrate and enhance the local field, thereby improving the detection performance of the detector. More importantly, the metal particle array is formed on the graphene layer, utilizing the high mobility and light transmittance of the graphene layer, and compared with other metals, it has good thermal conductivity, so the plasmon resonance performance of the metal particle array can be fully released to improve the overall performance of the detector.

[0044] Exemplarily, the material of the metal particles is selected from any one or a combination of two or more of aluminum, silver, zinc and gallium, preferably metal aluminum particles, but not limited thereto. The shape of the metal particles includes any one or a combination of two or more of sphere, column, pyramid and polyhedron, etc., preferably columnar, but not limited thereto.

[0045] refer to Figure 1 As shown, an electrode is grown by electron beam evaporation to form a Schottky contact or an Ohmic contact, and an electrode group 40 is prepared on the semiconductor substrate 10, the graphene layer 20 and the metal particle array 30 by photolithography. The electrode group 40 includes a first electrode 41 and a second electrode 42, wherein the first electrode 41 is formed on the exposed surface of the semiconductor substrate 10, and the second electrode 42 extends from the surface of the semiconductor substrate 10 to the surface of the metal particle array 30.

[0046] Exemplarily, the first electrode 41 and the second electrode 42 are both tooth electrodes, and the first electrode 41 includes a first connecting electrode 412 and a first tooth group 411 connected to the first connecting electrode 412, and the first tooth group 411 includes a plurality of first teeth arranged in parallel. The first connecting electrode 412 is arranged on the same side of the plurality of first teeth. The second electrode 42 includes a second connecting electrode 422 and a second tooth group 421 connected to the second connecting electrode 422, and the second tooth group 421 includes a plurality of second teeth arranged in parallel. The second connecting electrode 422 is arranged on the same side of the plurality of second teeth. The number of the second teeth is consistent with the number of the graphene layer 20. The number of the first teeth is consistent with the number of the second teeth. The first tooth group 411 and the second tooth group 421 are staggered and arranged opposite to each other. The second connecting electrode 422 partially covers and connects the graphene layer 20. The second tooth group 421 is arranged on the surface of the metal particle array 30 located on the graphene layer 20, and the projection of the second tooth group 421 in a direction perpendicular to the surface of the semiconductor substrate 10 on which it is located falls completely into the graphene layer 20, that is, each second tooth in the second tooth group 421 has a size smaller than the size of the corresponding graphene layer 20.

[0047] In a more specific implementation case, a Schottky contact is formed between the electrode group 40 and the semiconductor substrate 10. In this case, the material of the electrode group is selected from nickel / gold. In another more specific implementation case, a Schottky contact is formed between one of the electrode groups 40 and the semiconductor substrate 10, and the material of the electrode group 40 is selected from nickel / gold; another of the electrode groups 40 forms an ohmic contact with the semiconductor substrate 10, and the material of the electrode group 40 is selected from titanium / gold.

[0048] Finally, connect the wires to the PCB board electrodes and test to complete the preparation of the detector.

[0049] Compared with the prior art, the plasmon-enhanced detector according to the embodiment of the present invention is based on a strongly coupled metal particle array placed on a graphene layer structure, and a single-layer graphene layer does not affect the coupling between the metal particle array and the semiconductor substrate, and the light transmittance of the single-layer graphene layer can be as high as 98%. Graphene has a strong carrier transport capability, and this structure uses the plasmon field enhancement effect of the metal particle array to improve the carrier generation and separation capabilities, and also uses the graphene layer to improve the carrier transport capability, reducing the heat loss generated by the direct contact between the metal and the semiconductor, thereby regulating the overall performance of the detector's photoelectric conversion process and achieving overall performance improvement of the detector.

[0050] The plasmon-enhanced detector according to the embodiment of the present invention fully considers the three steps of photoelectric conversion, optimizes the three steps, and thus improves the detector response. First, in the carrier generation process, the plasmon effect of the metal particle array enhances the absorption of the photosensitive area, and the scattering effect of the metal particle array allows more light to enter the semiconductor substrate; secondly, in the carrier separation process, the local electric field is conducive to the separation of electron-hole pairs, and hot carriers overcome the Schottky barrier to enter the semiconductor substrate, promoting the transport of carriers; thirdly, the strongly coupled metal particle array is placed on a single-layer graphene layer structure, and the single-layer graphene layer does not affect the coupling between the metal particle array and the semiconductor substrate. At the same time, the single-layer graphene layer has a transmittance of up to 98%, and at the same time, it acts as an electrode to improve the carrier transport characteristics and enhance the overall performance of the semiconductor detector.

[0051] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A plasmon-enhanced detector, characterized in that: include: Semiconductor substrate; A graphene layer formed on the surface of the semiconductor substrate and exposing a portion of the semiconductor substrate; A metal particle array is formed on the surface of the graphene layer; as well as The electrode group is arranged on the exposed surface of the semiconductor substrate and partially extends on the surface of the metal particle array.

2. The plasmon-enhanced detector according to claim 1, characterized in that: The graphene layer is a single-layer graphene.

3. The plasmon-enhanced detector according to claim 1, characterized in that: The electrode group includes a first electrode and a second electrode. The first electrode is formed on the exposed surface of the semiconductor substrate, and the second electrode extends from the surface of the semiconductor substrate to the surface of the metal particle array.

4. The plasmon-enhanced detector according to claim 3, characterized in that: The first electrode and the second electrode are tooth electrodes, the first electrode has a first tooth group, the second electrode has a second tooth group, the first tooth group and the second tooth group are staggered and arranged opposite to each other, the second tooth group is arranged on the surface of the metal particle array, and the projection of the second tooth group in a direction perpendicular to the surface of the semiconductor substrate on which it is located completely falls into the graphene layer.

5. The plasmon-enhanced detector according to claim 3, characterized in that: A Schottky contact is formed between the electrode group and the semiconductor substrate; or, One of the electrode groups forms a Schottky contact with the semiconductor substrate, and the other electrode group forms an Ohmic contact with the semiconductor substrate.

6. The plasmon-enhanced deep ultraviolet detector according to claim 5, characterized in that: The electrode group is selected from nickel / gold electrodes and / or titanium / gold electrodes.

7. The plasmon-enhanced detector according to claim 1, characterized in that: The metal particle array includes a plurality of metal particles arranged in an array, and the metal particle array satisfies the following relationship: pd≦10nm, 10nm≦p≦100nm, 20nm≦d≦200nm, 20nm≦h≦90nm, wherein p is the periodic distance between the centers of any two adjacent metal particles, d is the diameter of each metal particle, and h is the thickness of each metal particle.

8. The plasmon-enhanced detector according to claim 7, characterized in that: The material of the metal particles is selected from any one of aluminum, silver, zinc and gallium, or a combination of two or more thereof.

9. The plasmon-enhanced detector according to claim 1, characterized in that: The material of the semiconductor substrate is selected from direct bandgap semiconductor materials.

10. A method for manufacturing a plasmon-enhanced detector according to any one of claims 1 to 9, characterized in that: include: forming a graphene layer on a surface of a semiconductor substrate; forming an array of metal particles on the surface of the graphene layer; An electrode group is formed on the surface of the semiconductor substrate and the surface of the metal particle array.

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