Graphene optoelectronic sensor and methods of making, assemblies, and systems thereof

Abstract

The application discloses a graphene photoelectric sensor, a preparation method, an assembly and a system thereof, wherein the photoelectric sensor comprises a source electrode, a drain electrode, a graphene layer and a light-transmitting organic layer with a gradient structure formed on a substrate, the graphene layer is arranged on the upper layer of the source electrode and the drain electrode in a covering manner, and the light-transmitting organic layer is formed on at least the surface of the graphene layer and is formed by at least two layers of organic material layers with different internal stresses. The application optimizes the structural arrangement of the sensitive component of the sensor, effectively utilizes the multilayer film structure with different stresses, sufficiently opens the band gap of the graphene material, improves the photoelectric performance of the product, and realizes the product.

Description

Technical Field

[0001] This invention relates to optoelectronic technology, and in particular to a graphene optoelectronic sensor and its preparation method, components, and system. Background Technology

[0002] Graphene is widely used in optoelectronic devices due to its excellent electrical, thermal, mechanical, and optical properties. Graphene has a zero-bandgap band structure, making it difficult to absorb large amounts of incident light. By adding a force field to graphene, the spatial inversion symmetry of the graphene lattice can be broken, thereby opening the bandgap. Opening the graphene bandgap can improve light absorption, thus enhancing the performance of graphene photodetectors. Currently, methods for applying stress to graphene mainly involve transferring graphene onto a metal sheet or polymer film and applying pressure to the metal sheet or polymer film to generate strain. Alternatively, stress can be applied to graphene using atomic force probes. These methods can effectively apply stress to graphene. However, these methods can easily damage the material. Furthermore, the substrates of graphene optoelectronic devices are generally silicon or silicon dioxide substrates, which are rigid substrates that cannot be directly subjected to tensile, compressive, or bending forces. Moreover, after the graphene photodetector is fabricated, it is inconvenient to add a large external force device to apply stress during use. Therefore, traditional methods of applying force fields cannot add stress to graphene in silicon-based graphene optoelectronic devices.

[0003] Most existing graphene optoelectronic devices employ symmetrical electrode structures, which require a bias voltage to operate. This results in high power consumption. Furthermore, the vast majority of existing graphene photodetectors are fabricated on rigid substrates such as silicon or silicon dioxide. Rigid substrates are inherently brittle and cannot be directly subjected to tensile, compressive, or torsional forces. Moreover, photodetectors are typically packaged after fabrication, making it impractical to apply external force to the graphene during use. Therefore, achieving performance improvement in graphene optoelectronic devices by adding a force field to the graphene on a rigid substrate through external force loading to modulate the graphene bandgap is extremely challenging.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a graphene photoelectric sensor and its preparation method, components and system. By optimizing the structural settings of the sensor's sensitive components, the multilayer thin film structure with different stresses is effectively utilized to fully open the band gap of the graphene material, thereby improving the photoelectric performance of the product and achieving product performance optimization.

[0006] To achieve the above objectives, embodiments of the present invention provide a graphene photoelectric sensor comprising a source electrode, a drain electrode, a graphene layer, and a light-transmitting organic layer with a gradient structure formed on a substrate. The graphene layer is disposed on top of the source and drain electrodes, and the light-transmitting organic layer is formed at least on the surface of the graphene layer and is composed of at least two layers of organic material with different internal stresses. Preferably, the drain electrode formed on the substrate can be a ring electrode structure, while the source electrode can be a columnar structure disposed at the center of the ring electrode structure. There is no direct electrical connection between the source and drain electrodes. Note that the substrate can be a silicon substrate with a silicon dioxide layer formed thereon, and both the source and drain electrodes are formed on the silicon dioxide layer.

[0007] In one or more embodiments of the present invention, the organic material of the organic material layer is selected from PMMA and PC. Preferably, the light-transmitting organic layer comprises three layers. When viewed from a direction away from the graphene layer, the first organic material layer is formed of a solution with a concentration of 1.1-1.5 wt.%, the second organic material layer is formed of a solution with a concentration of 2-3 wt.%, and the third organic material layer is formed of a solution with a concentration of 3.5-4.5 wt.%.

[0008] In one or more embodiments of the present invention, when viewed from a direction away from the graphene layer, the organic material layer constituting the light-transmitting organic layer is formed by coating with organic material slurries of different concentrations.

[0009] In one or more embodiments of the present invention, the light-transmitting organic layer comprises three layers. When viewed from a direction away from the graphene layer, the first organic material layer is formed of a PMMA solution with a concentration of 1.1-1.5 wt.%, the second organic material layer is formed of a PMMA solution with a concentration of 2-3 wt.%, and the third organic material layer is formed of a PMMA solution with a concentration of 3.5-4.5 wt.%.

[0010] In one or more embodiments of the present invention, the source electrode and the drain electrode are highly inconsistent asymmetric electrodes. 。

[0011] In one or more embodiments of the present invention, the height of the source electrode in the asymmetric electrode is 2-10 times that of the drain electrode.

[0012] In one or more embodiments of the present invention, the height of the source electrode in the asymmetric electrode is 200 nm and the height of the drain electrode is 100 nm.

[0013] In one or more embodiments of the present invention, a method for fabricating a graphene photoelectric sensor includes the following steps: A. preparing a substrate and forming a source electrode and a drain electrode on the substrate; B. transferring graphene to the substrate and forming a graphene layer covering the two electrodes above the source electrode and the drain electrode; C. forming at least two organic material layers with different internal stresses on the surface of the graphene layer to construct a light-transmitting organic layer.

[0014] In one or more embodiments of the present invention, the sensor assembly includes a graphene photoelectric sensor as described above and a functional component communicatively connected to the graphene photoelectric sensor, wherein the functional component is at least selected from communication cables and control processors. The component here can be a functional terminal assembly of the graphene photoelectric sensor connected to a cable or optical fiber.

[0015] In one or more embodiments of the present invention, the system (here, "system" can refer to a single-machine system capable of sensor detection, or a parallel / serial system linking multiple single-machine systems to meet multi-point data acquisition requirements) mainly includes a host and sensor devices communicatively connected to the host. The sensor devices include sensor assemblies as described above and / or graphene photoelectric sensors as described above. The host can be a computer, microprocessor, PLC, mobile phone, or other smart terminal, or a remote communication control platform, as long as it meets the communication and data interaction requirements with the sensors. The choice of host depends on factors such as the scale and performance requirements of the system.

[0016] Compared with the prior art, the graphene photoelectric sensor and its preparation method, components and system according to the embodiments of the present invention introduce an internal stress field by forming a gradient film structure on the graphene surface (such as spin coating), apply compressive stress to the graphene to open the graphene band gap, improve the light absorption capacity of graphene, and thus improve the performance of graphene photoelectric devices.

[0017] Gradient film structures can be achieved by coating graphene surfaces with PMMA films of varying concentrations. PMMA solutions of different concentrations are sequentially coated onto the graphene surface. During baking, the PMMA solution forms a polymer film, and the PMMA film shrinks during condensation, introducing internal stress into the graphene. By applying multiple layers of PMMA films with different concentrations, a surface coating layer with a concentration gradient is formed. This introduces significant internal stress while maintaining the light transmittance of the coating layer, thereby opening the graphene bandgap and improving the optoelectronic performance of the device.

[0018] Furthermore, traditional graphene optoelectronic devices typically employ symmetrical electrode structures, requiring a bias voltage during operation. This increases the device's power consumption. In contrast, this invention utilizes an asymmetrical electrode structure with two electrodes of different heights (by a factor of two). This asymmetrical electrode structure enables zero-bias operation, thereby reducing power consumption. Simultaneously, the height difference between the two electrodes creates an umbrella-like structure in the graphene, introducing more internal stress and effectively improving the device's photoelectric performance.

[0019] Meanwhile, the PMMA coating layer formed on the graphene surface in this invention can effectively protect the graphene from problems such as air doping during use, and can further improve the stability of the device. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a sensor according to an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of the manufacturing process of a sensor according to an embodiment of the present invention;

[0022] Figure 3 This is a schematic diagram of the manufacturing process of a sensor according to an embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram of the gradient structure formed by the light-transmitting organic layer according to an embodiment of the present invention. Detailed Implementation

[0024] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0025] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0026] Note that in the present invention, the "upper layer" refers to the view from the observer's perspective. Figure 1 Confirmed in time. Concentrations not specified in this invention are assumed to be mass concentrations.

[0027] PMMA (polymethyl methacrylate) is a high molecular weight polymer. It possesses advantages such as light weight, high specific strength, high light transmittance, and ease of molding. It is soluble in organic solvents such as anisole and can form good thin films with excellent dielectric properties. Its heat distortion temperature is 105℃, and the PMMA solution concentration is adjustable. Therefore, in this invention, PMMA coatings can be applied to the graphene surface via spin coating, followed by heat treatment to obtain PMMA coatings with different stresses.

[0028] Internal stress refers to the stress that remains inside an object after the external load is removed. It is caused by uneven volume changes in the macroscopic or microscopic structure of the material.

[0029] The reason why PMMA film coating causes changes in the internal stress state of graphene is as follows: PMMA solution is spin-coated onto graphene to form a micrometer-thick liquid film, which is then heat-treated (baked) to solidify. During the solidification process of the PMMA solution, shrinkage occurs. Since the thickness of graphene itself is only about 0.4 nm, the shrinkage of the micrometer-thick PMMA film directly leads to a compressive stress state in the graphene. Different concentrations of PMMA solution shrink to different degrees after solidification, resulting in different compressive stresses.

[0030] like Figures 1 to 4 As shown, the graphene photoelectric sensor according to a preferred embodiment of the present invention includes a source electrode, a drain electrode, a graphene layer, and a light-transmitting organic layer having a gradient structure formed on a substrate, wherein the graphene layer is disposed on the upper layer of the source electrode and the drain electrode, and the light-transmitting organic layer is formed on at least the surface of the graphene layer and is formed by at least two layers of organic material with different internal stresses.

[0031] like Figure 1 As shown, one embodiment of the photoelectric sensor of the present invention includes a source electrode 22, a drain electrode 21, a graphene layer 30, and a light-transmitting organic layer with a gradient structure formed on a substrate 1. The graphene layer 30 is disposed on top of the source electrode 22 and the drain electrode 21. The light-transmitting organic layer is formed at least on the surface of the graphene layer 30 and is formed by at least two layers of organic material with different internal stresses. The drain electrode 21 formed on the substrate 1 can be a ring electrode structure, while the source electrode 22 can be a columnar structure disposed at the center of the ring electrode structure. There is no direct electrical connection between the source electrode 22 and the drain electrode 21. Note that the substrate can be a silicon substrate 11 with a silicon dioxide layer 12 formed thereon, and both the source electrode 22 and the drain electrode 21 are formed on the silicon dioxide layer 12. Viewed from a direction away from the graphene layer, the organic material layer constituting the light-transmitting organic layer is formed by coating organic material slurries of different concentrations.

[0032] As a preferred embodiment, the light-transmitting organic layer comprises three layers. When viewed from the direction away from the graphene layer, the first organic material layer 31 is formed of a PMMA solution with a concentration of 1.1-1.5 wt.%; the second organic material layer 32 is formed of a PMMA solution with a concentration of 2-3 wt.%; and the third organic material layer 33 is formed of a PMMA solution with a concentration of 3.5-4.5 wt.%.

[0033] Example 01

[0034] In this embodiment, the silicon substrate is first ultrasonically cleaned using acetone, ethanol, and deionized water. Then, a source electrode with a height of 200 nm is fabricated using photolithography. Next, a drain electrode with a height of approximately 200 nm is fabricated using photolithography. Graphene is then transferred onto the substrate, arranged in an umbrella-like shape on the electrode. A PMMA film is then coated onto the graphene surface. Three layers of PMMA are applied: the first layer has a PMMA solution concentration of 1.1% in contact with the graphene, the second layer has a concentration of 2%, and the third layer has a concentration of 3.5%. After coating, the graphene and PMMA are patterned, completing the device.

[0035] Example 02

[0036] In this embodiment, the silicon substrate is first ultrasonically cleaned using acetone, ethanol, and deionized water. Then, a source electrode with a height of 100 nm is fabricated using photolithography. Next, a drain electrode with a height of approximately 100 nm is fabricated using photolithography. Graphene is then transferred onto the substrate, arranged in an umbrella-like shape on the electrode. A PMMA film is then coated onto the graphene surface. Three layers of PMMA are applied: the first layer has a PMMA solution concentration of 1.3% in contact with the graphene, the second layer has a concentration of 2.5%, and the third layer has a concentration of 4%. After coating, the graphene and PMMA are patterned, completing the device.

[0037] Example 03

[0038] In this embodiment, the silicon substrate is first ultrasonically cleaned using acetone, ethanol, and deionized water. Then, a source electrode with a height of 150 nm is fabricated using photolithography. Next, a drain electrode with a height of approximately 150 nm is fabricated using photolithography. Graphene is then transferred onto the substrate, arranged in an umbrella-like shape on the electrode. A PMMA film is then coated onto the graphene surface. Three layers of PMMA are applied: the first layer has a PMMA solution concentration of 1.5% in contact with the graphene, the second layer has a concentration of 3%, and the third layer has a concentration of 4.5%. After coating, the graphene and PMMA are patterned, completing the device.

[0039] Example 04

[0040] In this embodiment, the silicon substrate is first ultrasonically cleaned using acetone, ethanol, and deionized water. Then, a source electrode with a height of 200 nm is fabricated using photolithography. Next, a drain electrode with a height of approximately 200 nm is fabricated using photolithography. Graphene is then transferred onto the substrate, arranged in an umbrella-like shape on the electrode. A PC film is then coated onto the graphene surface. Three layers of PC film are required: the first layer has a PC solution concentration of 1.2% in contact with the graphene, the second layer has a concentration of 2.3%, and the third layer has a concentration of 3.7%. After coating, the graphene and PC are patterned, completing the device.

[0041] Example 05

[0042] In this embodiment, the silicon substrate is first ultrasonically cleaned using acetone, ethanol, and deionized water. Then, a source electrode with a height of 100 nm is fabricated using photolithography. Next, a drain electrode with a height of approximately 100 nm is fabricated using photolithography. Graphene is then transferred onto the substrate, arranged in an umbrella-like shape on the electrode. A PC film is then coated onto the graphene surface. Three layers of PC film are required: the first layer has a PC solution concentration of 1.4% in contact with the graphene, the second layer has a concentration of 2.6%, and the third layer has a concentration of 4.2%. After coating, the graphene and PC are patterned, completing the device.

[0043] Example 06

[0044] In this embodiment, the silicon substrate is first ultrasonically cleaned using acetone, ethanol, and deionized water. Then, a source electrode with a height of 150 nm is fabricated using photolithography. Next, a drain electrode with a height of approximately 150 nm is fabricated using photolithography. Graphene is then transferred onto the substrate, arranged in an umbrella-like shape on the electrode. A PC film is then coated onto the graphene surface. Three layers of PC film are applied: the first layer has a PC solution concentration of 1.25% in contact with the graphene, the second layer has a concentration of 2.8%, and the third layer has a concentration of 4.4%. After coating, the graphene and PC are patterned, completing the device.

[0045] Example 11

[0046] The only difference between this embodiment and Embodiment 01 is that: the source electrode is fabricated using photolithography, with a height of 200 nm; then, the drain electrode is fabricated using photolithography, with a height of approximately 100 nm. Figure 2 As shown; then graphene is transferred onto the substrate, with the graphene arranged in an umbrella shape on the electrodes. A PMMA film is then coated onto the graphene surface. The device fabrication process is as follows: Figure 3 As shown.

[0047] The electrodes employ an asymmetric structure design, enabling the device to operate under zero bias. Furthermore, the source and drain electrodes have a 100nm height difference, which allows the graphene to form an umbrella-like structure, effectively introducing internal stress and thus improving device performance. The gradient film structure can uniformly apply internal stress within the graphene. Initially, the PMMA film concentration in contact with the graphene is low, resulting in minimal introduced internal stress and preventing defects caused by the large internal stress generated during PMMA film shrinkage. The PMMA solution concentration is then gradually increased, gradually increasing the internal stress. While maintaining the transmittance of the coating layer, a larger internal stress is introduced, placing the entire graphene under significant compressive stress, thereby improving device performance. Simultaneously, the coating layer on the graphene surface effectively improves the device's stability and lifespan during use. (See schematic diagram). Figure 4 This cohesive stress structure enables the optimization and improvement of sensor product performance. The figure shows a schematic diagram of three different PMMA layers providing cohesive stress.

[0048] Example 12

[0049] The only difference between this embodiment and Embodiment 02 is that: the source electrode is prepared by photolithography, with an electrode height of 400nm; and then the drain electrode is prepared by photolithography, with a drain electrode height of approximately 100nm.

[0050] Example 13

[0051] The only difference between this embodiment and embodiment 03 is that the source electrode is prepared by photolithography, with an electrode height of 500 nm; and the drain electrode is prepared by photolithography, with a drain electrode height of approximately 100 nm.

[0052] Example 14

[0053] The only difference between this embodiment and embodiment 04 is that the source electrode is prepared by photolithography, with an electrode height of 800 nm; and then the drain electrode is prepared by photolithography, with a drain electrode height of approximately 100 nm.

[0054] Example 15

[0055] The only difference between this embodiment and embodiment 05 is that: the source electrode is prepared by photolithography, with an electrode height of 800nm; and then the drain electrode is prepared by photolithography, with a drain electrode height of approximately 100nm.

[0056] Example 16

[0057] The only difference between this embodiment and embodiment 06 is that: the source electrode is prepared by photolithography, with an electrode height of 1000nm; and then the drain electrode is prepared by photolithography, with a drain electrode height of approximately 100nm.

[0058] Testing revealed that the average energy consumption of samples from Examples 01-06 was effectively reduced by 10-15% compared to conventional sensors of the same type but with symmetrical electrode structures. Furthermore, the average energy consumption of samples from Examples 11-16 was effectively reduced by 30-60% compared to samples from Examples 01-06, with a significant reduction in sensor heat dissipation of over 15-20% and an increase in sensitivity of 20-30%.

[0059] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A graphene photoelectric sensor, comprising a source electrode, a drain electrode, a graphene layer, and a light-transmitting organic layer having a gradient structure formed on a substrate, wherein the graphene layer is disposed on top of the source electrode and the drain electrode, the light-transmitting organic layer is formed at least on the surface of the graphene layer and is formed of three layers of organic material with different internal stresses, wherein the organic material of the organic material layers is selected from PMMA and PC, and when viewed from a direction away from the graphene layer, the organic material layers constituting the light-transmitting organic layer are formed by coating organic material slurries of different concentrations, the light-transmitting organic layer comprising: The first organic material layer is formed by a solution with a concentration of 1.1-1.5 wt.%, the second organic material layer is formed by a solution with a concentration of 2-3 wt.%, and the third organic material layer is formed by a solution with a concentration of 3.5-4.5 wt.%. The source electrode and the drain electrode are highly inconsistent asymmetric electrodes.

2. The graphene photoelectric sensor as described in claim 1, characterized in that, The height of the source electrode in the asymmetric electrode is 2-10 times that of the drain electrode.

3. The graphene photoelectric sensor as described in claim 2, characterized in that, The height of the source electrode in the asymmetric electrode is 200 nm, and the height of the drain electrode is 100 nm.

4. The method for preparing the graphene photoelectric sensor according to any one of claims 1-3, comprising the following steps: A. Prepare the substrate and form the source and drain electrodes on the substrate; B. Transfer graphene to the substrate to form a graphene layer covering the source and drain electrodes. C. Form at least two organic material layers with different internal stresses on the surface of the graphene layer to construct a light-transmitting organic layer.

5. A sensor assembly comprising a graphene photoelectric sensor as described in any one of claims 1-3 and a functional component communicatively connected to the graphene photoelectric sensor, wherein the functional component is at least selected from a communication cable and a control processor.

6. A system comprising a host computer and sensor devices communicatively connected to the host computer, the sensor devices comprising a sensor assembly as claimed in claim 5 and / or a graphene photoelectric sensor as claimed in any one of claims 1-3.

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