Stacked graphene plasma terahertz light emitter and preparation and application thereof

Abstract

The invention discloses a stacked graphene plasma terahertz light emitter and preparation and application thereof. The light emitter is formed by stacking a graphene film on a SiO2 substrate by using the following method: soaking a copper foil deposited with graphene in an etching solution to carry out primary etching on the copper foil; graphene on the lower layer of the copper foil is removed, and the copper foil only covered with the graphene film on the upper layer is obtained; taking a soft material which can float in the etching liquid, making a hole which is equivalent to the copper foil in size in the middle, enabling the soft material to float on the surface of the etching liquid, and putting the copper foil of which the lower-layer graphene is removed into the hole until the copper foil is completely etched and the graphene film exists at the position of the hole; the etching liquid is pumped away, deionized water is used for cleaning the etching liquid, and the soft material floats on the surface of the deionized water; and putting the graphene film into a low-p-doped SiO2 substrate, enabling the graphene film to be located right above the low-p-doped SiO2 substrate, and pumping away the deionized water to obtain the stacked graphene plasma terahertz light emitter.

Description

Technical Field

[0001] The present invention belongs to the field of micro-nano optical control technology, and specifically relates to a stacked graphene plasma terahertz light emitter and a preparation and application thereof. Background Art

[0002] The basic research and devices of terahertz optoelectronics have received widespread attention in recent years and have been used in fields such as light detection, light modulation and light emission. This technology uses precious metals, semiconductors and other materials as raw materials. The surface plasmons in precious metals can directly convert inherent collective charge oscillations into free-space radiation. In terahertz transmitters, the emission material is the core part of the transmitting device, and the properties of the material will have a great impact on the emission capability of the device. Most of the transmitters currently used use precious metals. During use, problems such as untunability and instability caused by high damping are inevitable, which greatly affects the performance and limits the application scenarios. Summary of the invention

[0003] The present invention is made in order to increase the selection space of terahertz light emitters and provide a terahertz light emitter with a more compact structure and higher carrier mobility.

[0004] As one aspect of the present invention, it relates to a stacked graphene plasma terahertz light emitter, which is formed by stacking a graphene film on a SiO2 substrate using the following method:

[0005] (1) immersing the copper foil with the graphene deposited thereon in an etching solution to perform preliminary etching of the copper foil;

[0006] (2) removing the graphene layer under the copper foil to obtain a copper foil covered with a graphene film only on the upper layer;

[0007] (3) taking a soft material that can float in an etching solution, making a hole in the middle of the copper foil of a size comparable to that of the copper foil, so that the soft material floats on the surface of the etching solution, and placing the copper foil with the lower layer of graphene removed into the hole until the copper foil is completely etched and the graphene film exists at the position of the hole;

[0008] (4) extracting the etching liquid, cleaning the etching liquid with deionized water, and allowing the soft material to float on the surface of the deionized water;

[0009] (5) placing a low-p-doped SiO2 substrate, controlling the movement of the soft material so that the graphene film is located directly above the low-p-doped SiO2 substrate, and removing the deionized water so that the graphene film falls onto the low-p-doped SiO2 substrate below, thereby obtaining a stacked graphene plasma terahertz light emitter.

[0010] In certain feasible specific embodiments, the method further comprises continuously increasing the number of layers of graphene films stacked on the low p-doped SiO2 substrate by repeating steps (1) to (5).

[0011] In some feasible specific implementations, the etching solution is prepared from ferric nitrate nonahydrate, concentrated hydrochloric acid and deionized water in a ratio of 1 g: 1 mL: 25 mL.

[0012] In some feasible specific implementations, the copper foil with graphene deposited thereon is made by chemical vapor deposition.

[0013] In some feasible embodiments, the chemical vapor deposition method uses methane or acetylene as a carbon source.

[0014] In some feasible specific embodiments, the soft material is a filter membrane.

[0015] In some feasible specific implementations, the time required for the initial etching of the copper foil is 1 / 4 of the time required for the complete etching of the copper foil.

[0016] In some feasible specific implementations, the thickness of the low p-doped SiO2 substrate is 1 mm.

[0017] As another aspect of the present invention, it relates to a method for preparing a stacked graphene plasma terahertz light emitter, comprising:

[0018] (1) immersing the copper foil with the graphene deposited thereon in an etching solution to perform preliminary etching of the copper foil;

[0019] (2) removing the graphene layer under the copper foil to obtain a copper foil covered with a graphene film only on the upper layer;

[0020] (3) taking a soft material that can float in an etching solution, making a hole in the middle of the copper foil of a size comparable to that of the copper foil, so that the soft material floats on the surface of the etching solution, and placing the copper foil with the lower layer of graphene removed into the hole until the copper foil is completely etched and the graphene film exists at the position of the hole;

[0021] (4) extracting the etching liquid, cleaning the etching liquid with deionized water, and allowing the soft material to float on the surface of the deionized water;

[0022] (5) placing a low-p-doped SiO2 substrate, controlling the movement of the soft material so that the graphene film is located directly above the low-p-doped SiO2 substrate, and removing the deionized water so that the graphene film falls onto the low-p-doped SiO2 substrate below, thereby obtaining a stacked graphene plasma terahertz light emitter.

[0023] As a third aspect of the present invention, it relates to a modulator using the above-mentioned stacked graphene plasma terahertz light emitter.

[0024] As a fourth aspect of the present invention, it relates to a filter using the above-mentioned stacked graphene plasma terahertz light emitter.

[0025] As a fifth aspect of the present invention, it relates to a terahertz imaging device using the above-mentioned stacked graphene plasma terahertz light emitter.

[0026] As a sixth aspect of the present invention, it relates to a wireless terahertz communication device, using the above-mentioned stacked graphene plasma terahertz light emitter.

[0027] As a seventh aspect of the present invention, it relates to a terahertz sensor using the above-mentioned stacked graphene plasma terahertz light emitter.

[0028] The beneficial effects of the above technical solution provided by the embodiment of the present invention include at least:

[0029] The stacked graphene plasma terahertz light emitter provided by the present invention realizes a compact structure through the stacking of graphene, has high radiation intensity, and has excellent isotropic properties, provides significant flexibility and functionality for device applications, and has the advantages of small structure and high carrier mobility.

[0030] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0031] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the preparation process of the stacked graphene plasma terahertz light emitter provided in an embodiment of the present invention.

[0033] Figure 2a Optical photographs of stacked graphene plasma terahertz light emitters with different numbers of stacked graphene layers.

[0034] Figure 2b Schematic diagram of the transmittance results of stacked graphene plasma terahertz light emitters with different numbers of graphene stacking layers.

[0035] Figure 2c Raman spectrum of stacked graphene plasmonic terahertz light emitter for a single layer of stacked graphene.

[0036] Figure 3a and Figure 3b These are the terahertz time domain signals of the tested samples when the number of graphene stacking layers is 1 and 6, respectively.

[0037] Figure 3c This is a graph showing the relationship between graphene with different stacking numbers and the peak intensity of the terahertz time domain signal.

[0038] Figure 3d Schematic diagram of the relationship between the terahertz radiation intensity of a stacked graphene plasma terahertz light emitter with 6 stacked graphene layers and the azimuth angle. DETAILED DESCRIPTION

[0039] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0040] Embodiment 1

[0041] The embodiment of the present invention provides a stacked graphene plasma terahertz light emitter, which is formed by stacking a graphene film on a SiO2 substrate using the following method:

[0042] (1) immersing the copper foil with the graphene deposited thereon in an etching solution to perform preliminary etching of the copper foil;

[0043] (2) removing the graphene layer under the copper foil to obtain a copper foil covered with a graphene film only on the upper layer;

[0044] (3) Take a soft material that can float in the etching solution, make a hole in the middle that is the same size as the copper foil, so that the soft material floats on the surface of the etching solution, and put the copper foil with the lower layer of graphene removed into the hole until the copper foil is completely etched and the graphene film exists at the position of the hole;

[0045] (4) removing the etching liquid, cleaning it with deionized water, and allowing the soft material to float on the surface of the deionized water;

[0046] (5) Place a low-p-doped SiO2 substrate, control the movement of the soft material so that the graphene film is directly above the low-p-doped SiO2 substrate, and remove the deionized water so that the graphene film falls exactly onto the low-p-doped SiO2 substrate below, thereby obtaining a stacked graphene plasma terahertz light emitter.

[0047] In the embodiment of the present invention, the copper foil with graphene deposited thereon can be prepared by a physical vapor deposition method or a chemical vapor deposition method.

[0048] In a specific embodiment, the carbon source used when preparing the copper foil with graphene deposited thereon by chemical vapor deposition method can be methane or acetylene.

[0049] Specifically, acetylene is selected as a carbon source, and argon (Ar) and hydrogen (H2) are used as carrier gases to prepare the copper foil with graphene deposited thereon by chemical vapor deposition. The specific implementation process may include:

[0050] Before chemical vapor deposition, the copper foil is ultrasonically cleaned for 10 minutes using acetone, anhydrous ethanol, and deionized water, respectively. The thickness of the copper foil may be 25 μm.

[0051] The metal substrate after ultrasonic cleaning is placed in a quartz tube, and the quartz tube is placed in a constant temperature zone of a CVD tube furnace.

[0052] Introduce argon gas into the quartz tube and exhaust it at a large flow rate for 20 minutes to ensure that all the air in the tube is exhausted.

[0053] After the exhaust is completed, a mixed gas of 500 sccm of argon and 500 sccm of hydrogen is introduced, the temperature is raised to 1000° C. for 60 minutes, and the temperature is maintained constant for annealing for 30 minutes.

[0054] The hydrogen gas was adjusted to 0.5 sccm and the argon gas to 950 sccm, and maintained for 5 minutes, and then acetylene (C2H2) gas with a flow rate of 1.5 sccm was introduced for 10 minutes of growth. After the growth, the acetylene gas was turned off and the temperature was lowered to room temperature to obtain the copper foil with graphene deposited thereon, and the preparation of the graphene film was completed.

[0055] The preparation of the above graphene film can also be completed by referring to the existing technology. In order to avoid wrinkles or damage to the graphene film on the copper foil, the surface of the copper foil should be as smooth as possible, for example, the surface roughness should be less than Ra3.2. The size of the prepared graphene should generally be greater than 5 square centimeters.

[0056] The physical vapor deposition method is a technology that converts materials from solid to gaseous state through a physical process in a vacuum, and then deposits them on a substrate to form a thin film. The chemical vapor deposition (CVD) method is a technology that deposits materials on the surface of a substrate through a chemical reaction at high temperature. For the application of terahertz light emitters, the electron mobility, number of layers and uniformity of graphene are key factors. The grain size of graphene prepared by the physical vapor deposition method is small, the number of layers is uneven, and it is difficult to control. There is often thicker graphene at the grain boundary, and the few-layer graphene is disordered. When the chemical vapor deposition method deposits graphene on copper foil, methane or other carbon source gas is used, which decomposes at high temperature and forms graphene on the surface of the copper foil. Compared with the physical vapor deposition method, the chemical vapor deposition method can generate larger area and higher quality graphene films, and the number of layers is controllable and the uniformity is good, which makes the chemical vapor deposition method more suitable for terahertz light emitters.

[0057] After graphene is deposited on copper foil, the graphene film is transferred to a low p-doped SiO2 substrate using a polymer-free method to obtain a stacked graphene plasma terahertz light emitter. The graphene transfer operation can be referred to Figure 1 Polymer-free graphene transfer is a graphene transfer technique that does not rely on polymer assistance. This method avoids the problem of leaving polymer residues on the graphene surface, which is critical for applications that require clean graphene surfaces. The specific implementation process may include the following operations:

[0058] The copper foil with graphene deposited thereon was cut into squares with a side length of 1 cm.

[0059] Afterwards, step (1) is performed to immerse the cut copper foil in an etching solution for preliminary etching of the copper foil. Specifically, the cut copper foil is placed in a culture dish containing an etching solution and etched for a period of time. The etching solution is prepared by ferric nitrate nonahydrate, concentrated hydrochloric acid and deionized water in a ratio of 1g:1mL:25mL. If the graphene stays in the etching solution for too long, it may cause damage or over-etching of the graphene, thereby affecting its electronic properties and structural integrity.

[0060] After repeated experiments, the inventors found that controlling the etching time to 1 / 4 of the time required for complete etching can effectively avoid the influence of the etching solution on graphene. Through preliminary etching, part of the copper foil can be removed, but it will not be completely etched away. This can reduce the risk of graphene being damaged due to long-term contact with the etching solution. Preliminary etching allows the operator to monitor the etching process to ensure that it is not over-etched, thereby protecting the integrity and quality of graphene.

[0061] Next, step (2) is performed, and the graphene on the lower layer of the copper foil is blown off with a straw or a syringe to obtain a copper foil covered with a graphene film only on the upper layer. In this step, in order to prevent the removed graphene fragments from sticking to the copper foil again, the copper foil with the lower layer of graphene removed needs to be taken out and the clean etching solution is replaced in the culture dish.

[0062] Next, step (3) is performed to obtain a soft material that can float in the etching solution. The soft material can be a filter membrane. A hole (e.g., Figure 1 As shown in the figure), make it float on the surface of the etching solution, and then put the copper foil with the lower layer of graphene removed into the hole until the copper foil is completely etched and the graphene film exists at the position of the hole.

[0063] The inventors found that during the graphene film transfer process, if the applied force is uneven, the graphene may be subjected to greater force in some areas, causing the graphene in these areas to fold. Folding not only affects the structural integrity of graphene, but also may affect its electronic and optical properties. Moreover, uneven force may cause graphene to be subjected to excessive stress in some areas, causing fracture. The fracture of graphene will seriously affect its performance, especially in applications that require a complete graphene film. In addition, evenly distributed force helps to maintain the flatness of graphene, which is crucial for its performance in many applications, such as electronic devices and optical applications. Based on this, the inventors proposed that the soft material adopts a filter membrane, and the filter membrane is used to assist in the transfer of graphene. The filter membrane can reduce the fluctuation of the liquid surface and provide a point of force during the transfer. The filter membrane can float on the surface of the liquid and provide a uniform support surface, so that the force applied to the graphene during the transfer process is more uniform, ensuring that the force applied to the graphene during the transfer process is evenly distributed, and preventing the graphene from folding and breaking. The graphene film can be moved by touching the edge of the filter membrane.

[0064] In the embodiment of the present invention, by etching the copper foil in stages, the etching process can be effectively controlled, the risk of graphene damage can be reduced, and the graphene can be ensured to be subjected to uniform force during the transfer process, thereby achieving high-quality graphene transfer. The protection of graphene and the precise control of the etching process can be combined to achieve the best transfer effect.

[0065] Next, execute step (4), remove the etching solution in the culture dish and inject deionized water. After standing for a period of time, remove it again and add clean deionized water. Repeat this process several times to ensure that the etching solution is clean and the soft material floats on the surface of the deionized water. Water needs to be added slowly during this process, otherwise bubbles are easily formed under the filter membrane. The bubbles may form uneven forces under the graphene, causing damage to the graphene. Moreover, if the bubbles burst, the graphene will also be damaged. In addition, care must be taken to keep the graphene membrane continuously and stably present in the hole during this process.

[0066] Next, perform step (5) to place the target substrate, i.e., a low-p-doped SiO2 substrate, and use tweezers to control the movement of the filter membrane so that the graphene membrane is directly above the target substrate. Then, remove the deionized water so that the graphene membrane falls exactly on the target substrate below. Then, remove the filter membrane and dry it to obtain a stacked graphene plasma terahertz light emitter. During the water extraction process, the filter membrane will move with it. The filter membrane can be blocked with tweezers or adjusted in position to ensure that the graphene membrane is always directly above the target substrate.

[0067] "Low p-doped SiO2 substrate" generally refers to the introduction of positive charges (p-type doping) on ​​a silicon dioxide substrate by doping to adjust the electronic properties of graphene. "Low p-doping" means that the degree of doping is not high and the concentration of doped holes is low. Generally speaking, the doping concentration can range from 10^11cm-2 to 10^14cm-2. For example, by doping graphene with nitric acid (HNO3) vapor, the graphene carrier concentration can be adjusted over a wide range. In practical applications, low p-doping may mean that the doped graphene still maintains good electron mobility and fewer defects, which is beneficial to the performance of stacked graphene plasma terahertz light emitters. Silicon dioxide doping is a prior art, and the specific doping concentration can be selected according to the needs of specific applications.

[0068] By repeating the above steps (1)-(5), graphene films with different numbers of layers can be stacked on a low p-doped SiO2 substrate.

[0069] In the embodiment of the present invention, when preparing the stacked graphene plasma terahertz light emitter, during the cleaning of the copper foil for removing the lower graphene layer and the graphene film transfer process, it is necessary to ensure that the liquid flows evenly to avoid local flow that is too fast or too slow, which helps to maintain the uniformity of the force exerted on the graphene.

[0070] Figure 2a The graphene plasma terahertz light emitter with different number of graphene layers obtained by transferring the graphene film to the low p-doped SiO2 substrate by the polymer-free method is shown. By observing the graphene plasma terahertz light emitter with 1 to 6 layers of graphene stacked on the low p-doped SiO2 substrate, it can be seen that as the number of graphene layers increases, the color of the graphene also deepens. At the same time, it can also be seen that in the embodiment of the present invention, the edges of the transferred graphene layers are neat and there is no staggered protrusion, which proves that the graphene transfer and stacking method of the embodiment of the present invention can achieve accurate point-to-point transfer of the graphene film.

[0071] Figure 2bThe figure shows the results of testing the transmittance of stacked graphene plasma terahertz light emitters with different numbers of stacked graphene layers in the visible-near infrared band (500-1100nm). Since the single-layer absorption rate of graphene is 2.3%, the transmittance is about 97.7%, and as the number of stacked layers increases, the transmittance of graphene decreases linearly.

[0072] Figure 2c The Raman spectrum of the stacked graphene plasma terahertz light emitter of a single-layer stacked graphene is shown in the figure, where the excitation wavelength is 514nm. From the figure, we can see that our graphene sample has three obvious characteristic peaks, D, G and 2D peaks. The existence of the G peak indicates that there are sp 2 Hybridized carbon atoms, which is a typical feature of graphene. The intensity and width of the G peak can reflect the quality of graphene. The shape and position of the 2D peak can provide information about the number of graphene layers. The G peak and 2D peak intensities are almost the same, further indicating that the sample is a stacked graphene plasma terahertz light emitter of single-layer stacked graphene. The presence and intensity of the D peak can reflect the defect level in graphene. A low intensity D peak usually means fewer defects, which helps to improve the electronic properties of graphene.

[0073] The inventors used a terahertz time-domain spectroscopy test method, using a titanium sapphire femtosecond laser (central wavelength 800nm, pulse width 35fs, repetition frequency 1kHz) to focus the output light on a stacked graphene plasma terahertz light emitter with different numbers of stacked graphene layers under test, radiating terahertz waves and conducting a terahertz wave radiation signal test. Figure 3a and Figure 3b These are the terahertz time domain signals of the tested samples when the number of graphene stacking layers is 1 and 6. Figure 3a In the figure, the sample under test is a stacked graphene plasma terahertz light emitter of a single-layer graphene, and the two dotted lines are two groups of terahertz time-domain signals corresponding to any two azimuth angles obtained before and after a random rotation of an angle around the normal line of the sample. The experiment shows that: the product obtained by the method of the present invention can achieve strict stacking of each layer of graphene film, with neat edges and no protrusions, and the terahertz radiation of graphene is isotropic no matter how many layers of graphene film are stacked.

[0074] Figure 3c The relationship between the peak intensity of the terahertz time-domain signal and the number of graphene layers with different stacking numbers is statistically analyzed. It can be seen that the terahertz radiation intensity of the stacked graphene shows an increasing trend with the increase in the number of layers, and as the number of stacked graphene layers continues to increase, the terahertz radiation intensity begins to flatten out.

[0075] In order to further confirm that graphene terahertz radiation is isotropic, the inventors selected a stacked graphene plasma terahertz light emitter with 6 layers of graphene as a sample, rotated the sample around the normal direction for one circle, and obtained the relationship between the terahertz radiation intensity and the azimuth angle, as shown in Figure 2. Figure 3d As shown. Figure 3d It can be clearly seen that the peak value of the terahertz time domain signal shows a circular trend with the azimuth angle, indicating that stacked multilayer graphene exhibits isotropic terahertz radiation performance. As the number of stacked layers increases, only the intensity increases, and there is no azimuth angle dependence.

[0076] Compared with the prior art, the preparation method of the stacked graphene plasma terahertz light emitter of the present invention adopts a polymer-free method to transfer the graphene film. During the preparation process of the stacked graphene plasma terahertz light emitter, it is not necessary to apply polymers such as polymethyl methacrylate (PMMA) on the surface of the graphene film, which not only saves time but also can obtain a clean graphene surface; at the same time, the graphene can be easily transferred to the target position of the target substrate. Compared with the method of applying polymer, copper foil etching is cleaner and residue-free, and rapid and point-specific transfer of the graphene film can be achieved.

[0077] Compared with the existing technology, this method is more practical in the laboratory, specifically: (1) the filter membrane used is economical and easy to obtain. (2) The filter membrane is easier to cut, and multiple samples can be transferred simultaneously in the laboratory without being restricted by the filter membrane.

[0078] Compared with the traditional single-layer graphene light emitter, in the embodiment of the present invention, the stacked graphene plasma terahertz light emitter prepared has no coupling between the randomly stacked graphene layers, and the electroacoustic coupling will not be reduced as the number of layers increases, so the light traction effect is not greatly affected. In addition, as the number of stacked layers increases, the absorption of light by the multilayer structure is also enhanced, so the phenomenon of terahertz enhancement will be exhibited. As the number of stacked layers increases, the terahertz radiation intensity of graphene is also enhanced, and no matter how many layers are stacked, the intensity of its terahertz emission signal is isotropic with the sample azimuth angle. Through the preparation method of the stacked graphene plasma terahertz light emitter provided by the embodiment of the present invention, the appropriate number of stacked layers of graphene film can be selected according to the radiation intensity requirements to adjust the intensity of terahertz radiation.

[0079] Embodiment 2

[0080] Based on the same inventive concept, an embodiment of the present invention further provides a modulator using the stacked graphene plasma terahertz light emitter prepared in the above-mentioned embodiment 1.

[0081] Embodiment 3

[0082] Based on the same inventive concept, an embodiment of the present invention further provides a filter using the stacked graphene plasma terahertz light emitter prepared in the above-mentioned embodiment 1.

[0083] Embodiment 4

[0084] Based on the same inventive concept, an embodiment of the present invention further provides a terahertz imaging device, using the stacked graphene plasma terahertz light emitter prepared in the above-mentioned embodiment 1.

[0085] Embodiment 5

[0086] Based on the same inventive concept, an embodiment of the present invention further provides a wireless terahertz communication device, using the stacked graphene plasma terahertz light emitter prepared in the above-mentioned embodiment 1.

[0087] Embodiment 6

[0088] Based on the same inventive concept, an embodiment of the present invention further provides a terahertz sensor, which uses the stacked graphene plasma terahertz light emitter prepared in the above-mentioned embodiment 1.

[0089] Unless otherwise stated, any technical solution disclosed in the present invention disclosed above, if it discloses a numerical range, then the disclosed numerical range is a preferred numerical range, and any technician in the field should understand that the preferred numerical range is only a numerical value with a more obvious technical effect or representative value among many implementable numerical values. Since there are too many numerical values ​​to be exhaustive, the present invention discloses some numerical values ​​to illustrate the technical solution of the present invention, and the numerical values ​​listed above should not constitute a limitation on the scope of protection of the present invention.

[0090] If the words "first", "second", etc. are used in this article to limit components, those skilled in the art should know that the use of "first" and "second" is only to distinguish the components for the convenience of description. Unless otherwise stated, the above words have no special meaning.

[0091] In addition, unless otherwise stated, the terms used to indicate positional relationships or shapes in any of the technical solutions disclosed in the present invention include states or shapes that are approximate, similar, or close to them.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. A stacked graphene plasma terahertz light emitter, characterized in that: The graphene film is stacked on the SiO2 substrate using the following method: (1) immersing the copper foil with the graphene deposited thereon in an etching solution to perform preliminary etching of the copper foil; (2) removing the graphene layer under the copper foil to obtain a copper foil covered with a graphene film only on the upper layer; (3) taking a soft material that can float in an etching solution, making a hole in the middle of the copper foil of a size comparable to that of the copper foil, so that the soft material floats on the surface of the etching solution, and placing the copper foil with the lower layer of graphene removed into the hole until the copper foil is completely etched and the graphene film exists at the position of the hole; (4) extracting the etching liquid, cleaning the etching liquid with deionized water, and allowing the soft material to float on the surface of the deionized water; (5) placing a low-p-doped SiO2 substrate, controlling the movement of the soft material so that the graphene film is located directly above the low-p-doped SiO2 substrate, and removing the deionized water so that the graphene film falls onto the low-p-doped SiO2 substrate below, thereby obtaining a stacked graphene plasma terahertz light emitter.

2. The stacked graphene plasma terahertz light emitter according to claim 1, characterized in that: The method also includes, by repeating steps (1) to (5), continuously increasing the number of graphene film layers stacked on the low p-doped SiO2 substrate.

3. The stacked graphene plasma terahertz light emitter according to claim 1, characterized in that: The etching solution is prepared from ferric nitrate nonahydrate, concentrated hydrochloric acid and deionized water in a ratio of 1 g: 1 mL: 25 mL.

4. The stacked graphene plasma terahertz light emitter according to claim 1, characterized in that: The copper foil with graphene deposited thereon is prepared by chemical vapor deposition.

5. A method for preparing a stacked graphene plasma terahertz light emitter, characterized in that: include: (1) immersing the copper foil with the graphene deposited thereon in an etching solution to perform preliminary etching of the copper foil; (2) removing the graphene layer under the copper foil to obtain a copper foil covered with a graphene film only on the upper layer; (3) taking a soft material that can float in an etching solution, making a hole in the middle of the copper foil of a size comparable to that of the copper foil, so that the soft material floats on the surface of the etching solution, and placing the copper foil with the lower layer of graphene removed into the hole until the copper foil is completely etched and the graphene film exists at the position of the hole; (4) extracting the etching liquid, cleaning the etching liquid with deionized water, and allowing the soft material to float on the surface of the deionized water; (5) placing a low-p-doped SiO2 substrate, controlling the movement of the soft material so that the graphene film is located directly above the low-p-doped SiO2 substrate, and removing the deionized water so that the graphene film falls onto the low-p-doped SiO2 substrate below, thereby obtaining a stacked graphene plasma terahertz light emitter.

6. A modulator, characterized in that: Use the stacked graphene plasma terahertz light emitter described in any one of claims 1 to 4.

7. A filter, characterized in that: Use the stacked graphene plasma terahertz light emitter described in any one of claims 1 to 4.

8. A terahertz imaging device, characterized in that: Use the stacked graphene plasma terahertz light emitter described in any one of claims 1 to 4.

9. A wireless terahertz communication device, characterized in that: Use the stacked graphene plasma terahertz light emitter described in any one of claims 1 to 4.

10. A terahertz sensor, characterized in that: Use the stacked graphene plasma terahertz light emitter described in any one of claims 1 to 4.

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