Microwave energy collector based on two-dimensional material and preparation method thereof

Abstract

The invention discloses a microwave energy collector based on a two-dimensional material and a preparation method thereof. The microwave energy collector comprises a substrate (1), an energy conversion layer (2) and two electrodes (3), the energy conversion layer is arranged on the substrate, and the two electrodes are attached to the energy conversion layer; the energy conversion layer is made of a two-dimensional material; grid voltage is loaded between the substrate and the electrodes, and after the microwave energy collector receives microwaves, potential difference can be generated between the two electrodes. According to the microwave energy collector, the energy conversion layer is made of the two-dimensional material, and the microwave energy collector and the energy conversion layer based on the two-dimensional material can achieve the effects of collecting microwave energy and converting the microwave energy into electric potential energy.

Description

Technical Field

[0001] The present invention relates to a microwave energy harvesting device, and particularly to a microwave energy harvester based on two-dimensional materials and a preparation method thereof. Background Art

[0002] Currently, two technical routes are adopted to implement microwave energy harvesters. One is based on the rectifying characteristics of PN junctions, and the other is based on the nonlinear Hall effect.

[0003] However, each of these two technical routes has its own disadvantages. Specifically,

[0004] For the microwave energy harvester based on the rectifying characteristics of PN junctions, its disadvantages are as follows:

[0005] 1) Affected by the working mechanism of the PN junction, it is impossible to harvest low-power microwave energy. The formation of the PN junction will generate a potential barrier in the junction region. Electrons need to obtain sufficient energy to cross this potential barrier. The energy of electrons mainly comes from absorbing the energy of external electromagnetic waves. Therefore, only when the energy of the electromagnetic wave is greater than the energy of the electron transition potential barrier can the energy harvesting and conversion be realized. Affected by the PN junction potential barrier, the device based on the PN junction rectification effect has an almost zero conversion efficiency for electromagnetic waves with a power lower than 100 nW / cm 2 . And the power of the electromagnetic waves around us is generally lower than 10 nW / cm 2 . Therefore, it is very difficult for the energy harvester based on the PN junction rectifying characteristics to have practical applications.

[0006] 2) Affected by the junction capacitance of the PN junction, it cannot work in the high-frequency region. The characteristic of capacitance is that it has no rectifying effect on high-frequency signals. The specific cut-off operating frequency depends on the resistance of the circuit and the specific capacitance of the PN junction. Generally speaking, it cannot effectively harvest high-frequency signals, further limiting its application scenarios.

[0007] For the microwave energy harvester based on the nonlinear Hall effect, its disadvantage is that the working mechanism has too high requirements for materials, requiring the material itself to have a Berry curvature dipole moment, and only when the polarization frequency of the electromagnetic wave is perpendicular to the mirror surface of the material can a Hall signal be generated. Therefore, to a certain extent, it limits its application prospects. Summary of the Invention

[0008] The purpose of the present invention is to provide a microwave energy harvester based on two-dimensional materials and a preparation method thereof, which can harvest microwave energy and convert the microwave energy into electric potential energy.

[0009] To achieve the above technical purpose, the present invention adopts the following technical solutions:

[0010] A microwave energy harvester based on two-dimensional materials, the microwave energy harvester comprising a substrate, an energy conversion layer, and two electrodes;

[0011] The energy conversion layer is disposed on the substrate, and the two electrodes are attached to the energy conversion layer;

[0012] The energy conversion layer is a two-dimensional material.

[0013] Further, a gate voltage is applied between the substrate and the electrode, and after the microwave energy harvester receives microwaves, a potential difference can be generated between the two electrodes.

[0014] Further, a protective coating is provided on the microwave energy harvester.

[0015] Further, the microwave energy harvester is provided with an antenna for receiving microwave energy.

[0016] Further, the material of the substrate is SiO 2 / Si, SiN / Si, Al 2 O 3 / Si, or HfO 2 / Si.

[0017] Further, the material of the protective coating is BN, Al 2 O 3 , SiO 2 , HfO 2 or PMMA.

[0018] Further, the material of the electrode is one or several of titanium, palladium, gold, and chromium; the thickness of the electrode is set in the range of 5-200 nm.

[0019] A method for fabricating a microwave energy harvester, comprising:

[0020] Step 1, providing a substrate;

[0021] Step 2, forming a layer of two-dimensional material on the substrate as the energy conversion layer;

[0022] Step 3, fabricating electrodes on the energy conversion layer to form a microwave energy harvester.

[0023] Further, the fabrication method further comprises:

[0024] Step 4, fabricating a radio wave collection antenna on the substrate.

[0025] Further, the fabrication method further comprises:

[0026] Step 5, covering a protective coating on the microwave energy harvester.

[0027] In the microwave energy harvester of the present invention, the material used for the energy conversion layer is a two-dimensional material. Based on the energy conversion layer of this two-dimensional material, the microwave energy harvester can achieve the effect of "collecting microwave energy and converting the microwave energy into electric potential energy".

[0028] Compared with the traditional radio wave energy harvester with diode rectification, the microwave energy harvester of the present invention has the following advantages:

[0029] 1) Because it is not restricted by the PN junction barrier, the microwave energy harvester can respond to low-power radio waves;

[0030] 2) Because it is not restricted by the PN junction capacitance, the microwave energy harvester can respond to radio waves of all frequencies;

[0031] 3) The microwave energy harvester is not restricted by specific working mechanisms and material types;

[0032] 4) The microwave energy harvester is not restricted by the polarization direction of the incident electromagnetic wave. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 and Figure 2 FIG. is a schematic structural diagram of a microwave energy harvester based on two-dimensional materials according to Embodiment 1 of the present invention. Among them, Figure 1 is a side view, Figure 2 is a top view; Figure 2 The protective cover layer is hidden;

[0034] Figure 3 and Figure 4 FIG. is a schematic structural diagram of a microwave energy harvester based on two-dimensional materials according to Embodiment 2 of the present invention. Among them, Figure 3 is a side view, Figure 4 is a top view;

[0035] Figure 5 FIG. is a graph showing the relationship between the output DC voltage and the microwave power of the microwave energy harvester according to Embodiment 2 of the present invention;

[0036] Figure 6 FIG. is a graph showing the relationship between the output DC voltage and the microwave frequency of the microwave energy harvester according to Embodiment 2 of the present invention;

[0037] Figure 7 FIG. is a graph showing the relationship between the energy conversion efficiency and the microwave power density of the microwave energy harvester according to Embodiment 2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0038] The present invention will be further described below with specific embodiments:

[0039] Embodiment 1:

[0040] Embodiment 1 provides a microwave energy harvester based on two-dimensional materials. The technical route adopted by this microwave energy harvester is completely different from the "microwave energy harvester based on the rectifying characteristics of PN junctions" and the "microwave energy harvester based on the nonlinear Hall effect" mentioned in the background technology, and belongs to a completely new technical route.

[0041] The specific mechanism for implementing the above-mentioned new technical route is as follows:

[0042] Refer to Figure 1 and Figure 2 , the microwave energy harvester of this embodiment includes a substrate 1, an energy conversion layer 2, and two electrodes 3.

[0043] The energy conversion layer 2 is attached to the substrate 1,

[0044] The two electrodes 3 are attached to the energy conversion layer 2, and the electrodes 3 are in direct contact with the energy conversion layer 2.

[0045] The energy conversion layer 2 is located between the electrodes 3 and the substrate 1, that is to say, there is an energy conversion layer 2 between the two electrodes 3 and the substrate 1.

[0046] On the energy conversion layer 2, the two electrodes 3 are separated, and there is a certain distance between the two electrodes 3.

[0047] The most important innovation of the microwave energy harvester of this embodiment is that the energy conversion layer 2 is made of two-dimensional materials, and the crystal structure of the two-dimensional materials does not have mirror symmetry. The material of the energy conversion layer 2 can be polycrystalline two-dimensional materials, single-crystalline two-dimensional materials, or heterostructures of two-dimensional materials.

[0048] The microwave energy harvester of this embodiment can achieve the circuit function of "collecting microwave energy and converting it into electric potential energy". Typical applications in daily life include wireless charging of mobile phones, and it can also directly drive external load devices, such as driving drones to work without interruption, driving micro-robots into the human body to kill diseased cells, etc.

[0049] The working principle of the microwave energy harvester of this embodiment for specifically realizing the function of "wirelessly collecting microwave energy" is as follows:

[0050] A gate voltage V is applied between the substrate 1 and the electrodes 3 BG , and by adjusting V BG the microwave energy harvester is in the state with the highest energy conversion efficiency, that is, the state with the largest ratio of output energy / input energy.

[0051] After receiving the externally incoming microwave, the non-linear effect of the microwave energy collector converts the absorbed microwave signal into a DC signal, generating a potential difference between the two electrodes 3, that is, realizing the conversion of microwave energy to electric potential energy.

[0052] By setting up a power storage system between the two electrodes 3, the generated electric potential energy can be stored. Or a load device can be directly set between the two electrodes 3 to directly drive the operation of an external load device.

[0053] A protective covering layer 4 is also provided on the energy conversion layer 2 and the electrodes 3 to play a protective role.

[0054] In addition, in order to improve the microwave energy collection efficiency, an antenna can be set on the substrate 1, so that the microwave energy collector can receive microwave energy more efficiently.

[0055] The microwave energy collector of this embodiment has the following advantages:

[0056] In the microwave energy collector of Embodiment 1, the material used for the energy conversion layer 2 is a two-dimensional material with low symmetry. Based on the energy conversion layer 2 of this two-dimensional material, the microwave energy collector can achieve the effect of "collecting microwave energy and converting the microwave energy into electric potential energy".

[0057] Compared with the traditional radio wave energy collector with diode rectification, the microwave energy collector of Embodiment 1 also has the following advantages:

[0058] 1) Because it is not restricted by the PN junction barrier, the microwave energy collector can respond to low-power radio waves;

[0059] 2) Because it is not restricted by the PN junction capacitance, the microwave energy collector can respond to radio waves of all frequencies;

[0060] 3) The microwave energy collector is not restricted by specific working mechanisms and material types;

[0061] 4) The microwave energy collector is not restricted by the polarization direction of the incident electromagnetic wave.

[0062] It should be noted that

[0063] The material of the substrate 1 can be SiO 2 / Si, SiN / Si, Al 2 O 3 / Si, HfO 2 / Si, etc.

[0064] The material of the protective covering layer 4 can be BN, Al 2 O 3 、SiO 2, HfO 2 , PMMA, and so on.

[0065] The material of the electrode 3 can be one or several of materials such as titanium, palladium, gold, chromium, etc. The thickness of the electrode 3 is usually between 5 - 200 nm.

[0066] Embodiment 2:

[0067] Embodiment 2 provides a microwave energy harvester. This embodiment 2 embodies the original concept of the present invention.

[0068] The microwave energy harvester provided by Embodiment 2 is a universal microwave energy harvester that does not require the participation of a PN junction. This microwave energy harvester only requires the overall structure of the material to break the central inversion symmetry. In terms of the energy band structure, it means that the energy band structure breaks the central inversion symmetry. The specific working mechanism of the microwave energy harvester is not limited and can be a combination of any one or several microscopic mechanisms that are known to produce nonlinear effects.

[0069] Specifically, since the nonlinear effect of this microwave energy harvester comes from the breaking of the central inversion symmetry of the material itself and does not require the participation of a PN junction, it can not only collect and convert extremely low-power radio wave energy, but is also not limited by the radio wave frequency, having broad application prospects.

[0070] In addition, the microwave energy harvester of this Embodiment 2 is not limited by the specific working mechanism. It only requires the material to break the central inversion symmetry, and the generation of this symmetry breaking can be a characteristic of the material itself or caused by external factors such as stress, interface effect, impurity scattering, etc. This microwave energy harvester has no requirement for the polarization direction of the electromagnetic wave and can be incident on the sample in any direction. The generation of the DC signal is not limited to the Hall signal, and the DC signal can be measured in any direction of the sample.

[0071] Embodiment 2 also provides a preparation method of a microwave energy harvester based on the intrinsic characteristics of two-dimensional materials and proposes a method for regulating the performance of the microwave energy harvester.

[0072] The preparation method of the microwave energy harvester is as follows:

[0073] The microwave energy harvester includes:

[0074] A substrate;

[0075] Two-dimensional material, located above the substrate;

[0076] An electrode, located above the two-dimensional material and in contact with the two-dimensional material;

[0077] An antenna (whether to add it is selected according to the microwave energy harvesting efficiency);

[0078] A protective layer, located above the two-dimensional material and the electrode, for protecting the sample;

[0079] An external circuit.

[0080] The preparation method is as follows:

[0081] Step 1: Provide a substrate, usually SiO 2 / Si substrate. Grow an insulating layer on the conductive Si substrate. The insulating layer can be SiO 2 , SiN, HfO 2 , Al 2 O 3 , or directly use a commercial SiO 2 / Si substrate, SiN / Si substrate, HfO 2 / Si substrate, Al 2 O 3 / Si substrate, etc.

[0082] Step 2: Form a layer of two-dimensional material on the substrate obtained in Step 1 by methods such as chemical vapor deposition, mechanical dissociation, physical transfer, or molecular beam epitaxy. This layer of two-dimensional material serves as the energy conversion layer.

[0083] Step 3: Fabricate electrodes on the two-dimensional material obtained in Step 2 to form a microwave energy collector.

[0084] Step 4: To enhance the efficiency of the microwave energy collector in absorbing wireless signals, a radio wave collecting antenna can be fabricated on the substrate in Step 1.

[0085] Step 5: Cover a protective layer above the sample and the electrodes. The material of the protective layer is usually an insulating layer, which can be BN, Al 2 O 3 , SiO 2 , HfO 2 , PMMA, etc.

[0086] Step 6: Connect a voltmeter to read the DC voltage signal generated by the microwave energy collector.

[0087] The thickness of the two-dimensional material is less than 100 nm. The electrode material is selected from one or more of materials such as titanium, palladium, gold, chromium, etc. The selection principle is to reduce the contact resistance between the metal and the material.

[0088] The regulation method of the microwave energy harvester includes: by regulating the Fermi surface of the two-dimensional material in the microwave energy harvester, the regulation of the band asymmetry of the two-dimensional material is realized, and further the regulation of the collection efficiency of the microwave energy harvester is realized. Specifically, the increase or decrease of the Fermi surface of the two-dimensional material will enhance or weaken the band asymmetry of the two-dimensional material, thereby realizing the enhancement or weakening of the performance of the microwave energy harvester. The enhancement or weakening of the performance of the microwave energy harvester is specifically manifested in the increase or decrease of the collected DC signal.

[0089] The regulation methods of the Fermi surface of the two-dimensional material of the microwave energy harvester include: gate voltage method, ion implantation doping method, chemical doping method, stress application method, etc.

[0090] Compared with the traditional diode rectifier device, because it is not limited by the PN junction barrier, the microwave energy harvester of Embodiment 2 can respond to low-power radio waves.

[0091] Compared with the traditional diode rectifier device, because it is not limited by the PN junction capacitance, the microwave energy harvester of Embodiment 2 can respond to radio waves of all frequencies.

[0092] Compared with the radio wave energy harvester based on the nonlinear Hall effect, the microwave energy harvester of Embodiment 2 is not limited by the specific working mechanism and material type.

[0093] Compared with the radio wave energy harvester based on the nonlinear Hall effect, the microwave energy harvester of Embodiment 2 is not limited by the polarization direction of the incident electromagnetic wave.

[0094] For the microwave energy harvester of Embodiment 2, its key points mainly lie in the following two aspects:

[0095] 1) The microwave energy harvester of Embodiment 2 does not require the existence of PN. The energy conversion relies on the nonlinear effect generated by the breaking of the central inversion symmetry of the material itself.

[0096] 2) The working mechanism of the microwave energy harvester of Embodiment 2 has no specific limitation. As long as the material breaks the central inversion symmetry, it can be one or several of the physical mechanisms of nonlinear effects (Berry curvature dipole moment, quantum metric dipole moment, nonlinear Drude effect, scattering, etc.).

[0097] See Figure 3 and Figure 4 , the microwave energy harvester provided by Embodiment 2 includes a substrate 1, a two-dimensional material 2, a metal electrode 3, and a protective layer 4. It may also include an antenna for improving the microwave energy collection efficiency, etc.

[0098] The substrate is usually SiO 2 / Si substrate; however, it can also be other substrates, such as SiN / Si substrate, HfO 2 / Si substrate Al 2 O 3 / Si substrate, etc. The thickness of the insulating layer SiO 2 , SiN, HfO 2 , Al 2 O 3 etc. on the substrate is not specifically required. The Si in the substrate belongs to the conductive layer and is used to adjust the Fermi level position of the two-dimensional material and the magnitude of the electric field. By regulating the Fermi level of the two-dimensional material in the microwave energy collector, the regulation of the energy band asymmetry of the two-dimensional material is achieved, and then the regulation of the collection efficiency of the microwave energy collector is realized. Specifically, the increase or decrease of the Fermi level of the two-dimensional material will enhance or weaken the energy band asymmetry of the two-dimensional material, thereby enhancing or weakening the performance of the microwave energy collector. The enhancement or weakening of the performance of the microwave energy collector is specifically manifested in the increase or decrease of the collected DC signal.

[0099] See Figure 3 , add a two-dimensional material on the insulating layer of the substrate. The thickness of the two-dimensional material is usually less than 100 nm. The method of adding the two-dimensional material can be chemical vapor deposition, mechanical dissociation, physical transfer, molecular beam epitaxy method, etc. The types of the two-dimensional material can be two-dimensional material single crystal, two-dimensional material heterojunction, two-dimensional material Moiré superlattice, two-dimensional material superstructure, two-dimensional material polycrystal, etc.

[0100] Prepare electrode contacts for the two-dimensional material to read out the DC voltage signal. The shape of the electrode on the sample can be as Figure 4 shown, or two rectangular electrodes can be in direct contact with the sample, etc. The shape of the electrode on the substrate is not required. The thickness of the electrode is usually between 5 - 200 nm.

[0101] In order to enhance the efficiency of the microwave energy collector in absorbing wireless signals, a radio wave collection antenna can be selectively prepared on the insulating layer of the substrate. The shape of the antenna is designed according to the specific absorption frequency band.

[0102] Add a protective layer above the sample and the electrode to protect the two-dimensional material. The protective layer material can be BN, Al 2 O 3 , SiO 2 , HfO 2 , PMMA, etc. The method of adding the protective layer can be growth, evaporation, transfer, spin coating, etc.

[0103] Connect to an external circuit to read out the DC voltage signal generated by the microwave energy collector.

[0104] See Figure 5, which shows the relationship between the DC output voltage and the incident microwave energy.

[0105] See Figure 6 , which shows the relationship between the DC output voltage and the incident microwave frequency.

[0106] See Figure 7 , which shows the relationship between the output power and the incident microwave energy density.

[0107] The above are only the preferred embodiments of the present invention, and are not used to limit the protection scope of the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A microwave energy harvester based on two-dimensional materials, characterized in that: The microwave energy collector comprises a substrate (1), an energy conversion layer (2) and two electrodes (3); The energy conversion layer (2) is arranged on the substrate (1), and the two electrodes (3) are arranged in contact with the energy conversion layer (2); The energy conversion layer (2) is a two-dimensional material.

2. The microwave energy harvester based on two-dimensional materials according to claim 1, characterized in that: A gate voltage is loaded between the substrate (1) and the electrode (3), and after the microwave energy collector receives the microwave, a potential difference can be generated between the two electrodes (3).

3. The microwave energy harvester based on two-dimensional materials according to claim 1, characterized in that: A protective covering layer (4) is arranged on the microwave energy collector.

4. The microwave energy harvester based on two-dimensional materials according to claim 1, characterized in that: The microwave energy collector is provided with an antenna for receiving microwave energy.

5. The microwave energy harvester based on two-dimensional materials according to claim 1, characterized in that: The material of the substrate (1) is SiO2 / Si, SiN / Si, Al2O3 / Si, or HfO2 / Si.

6. The microwave energy harvester based on two-dimensional materials according to claim 3, characterized in that: The material of the protective covering layer (4) is BN, Al2O3, SiO2, HfO2 or PMMA.

7. The microwave energy harvester based on two-dimensional materials according to claim 1, characterized in that: The material of the electrode (3) is one or more of titanium, palladium, gold and chromium; the thickness of the electrode (3) is set in the range of 5-200 nm.

8. A method for preparing a microwave energy collector, characterized in that: include: Step 1, providing a substrate (1); Step 2, forming a layer of two-dimensional material as an energy conversion layer on the substrate (1); Step 3, preparing an electrode (3) on the energy conversion layer to form a microwave energy collector.

9. The method for preparing a microwave energy collector according to claim 8, characterized in that: The preparation method further comprises: Step 4, preparing a radio wave collecting antenna on the substrate (1).

10. The method for preparing a microwave energy collector according to claim 8, characterized in that: The preparation method further comprises: Step 5, covering the microwave energy collector with a protective covering layer (4).

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