An upright graphene heterojunction, a preparation method, a photodetector and application

Abstract

The present application relates to a kind of vertical graphene heterojunction, preparation method, photodetector and application, including substrate and vertical graphene layer, the vertical graphene layer includes at least two vertical graphene resonant rings arranged on the substrate, and the vertical graphene resonant ring is sequentially spaced from inside to outside.

Description

Technical Field

[0001] The present invention relates to the field of photoelectric detection, and in particular to an upright graphene heterojunction, a preparation method, a photoelectric detector and applications. Background Art

[0002] Photodetectors are key components for the efficient conversion of optical and electrical signals, playing an irreplaceable role in a wide range of fields, including optical communications, environmental monitoring, biomedical imaging, and quantum information processing. This is particularly true in the near-infrared (NIR) band (e.g., 1550 nm), where the wavelength perfectly matches the low-loss transmission window of optical fiber communications. Therefore, the performance of photodetectors in this band directly determines the transmission rate and overall stability of optical communication systems.

[0003] Traditional infrared photodetectors utilize a silicon-based substrate coupled with three-dimensional graphene. 3D graphene, due to its high surface area and porous structure, effectively absorbs light. To achieve optimal infrared detection performance, large areas of 3D graphene are typically grown on silicon substrates. However, this large-scale production of 3D graphene increases the mass of the photodetector, hindering its miniaturization and lightweighting. Summary of the Invention

[0004] Based on this, it is necessary to provide an upright graphene heterojunction, a preparation method, a photodetector and its application to address the problem that the detection capability and lightweight of infrared photodetectors cannot be taken into account at the same time.

[0005] A vertical graphene heterojunction comprises a substrate and a vertical graphene layer, wherein the vertical graphene layer comprises at least two vertical graphene resonant rings arranged on the substrate, and the vertical graphene resonant rings are sequentially spaced from the inside to the outside.

[0006] In one embodiment, the number of the upright graphene resonant rings is two, three or four.

[0007] In one embodiment, the distance between two adjacent upright graphene resonant rings is 155 nm-465 nm.

[0008] In one embodiment, an avoidance gap is provided on the upright graphene resonant ring.

[0009] In one embodiment, the upright graphene layer includes a first upright graphene connecting line, and two ends of the first upright graphene connecting line are respectively located on the two upright graphene resonant rings.

[0010] In one embodiment, a portion of the upright graphene resonant ring and another portion of the upright graphene resonant ring are disconnected within the upright graphene layer.

[0011] A method for preparing a vertical graphene heterojunction, comprising:

[0012] Hollowing out a relief opening on the mask plate that matches the designed shape of the upright graphene layer;

[0013] The mask is placed on the substrate and then the upright graphene layer is grown.

[0014] In one embodiment, the preparation method further comprises:

[0015] The mask plate and substrate are transferred into a quartz tube, evacuated, and then heated. Hydrogen is continuously introduced during the heating process, wherein the flow rate of hydrogen is 0.5 sccm-2 sccm. The material of the mask plate is stainless steel.

[0016] In one embodiment, the growth temperature of the upright graphene layer is 500° C.-600° C., and the mask plate is made of stainless steel.

[0017] A photodetector comprises a power source and the upright graphene heterojunction, wherein the upright graphene layer is connected to the positive electrode of the power source, and the substrate is connected to the negative electrode of the power source.

[0018] An application of the upright graphene heterojunction in infrared signal transmission.

[0019] The beneficial effects of the present invention are:

[0020] The present invention designs the pattern of the upright graphene layer to reduce the area of ​​the upright graphene layer and obtains an upright graphene resonant ring, thereby reducing the weight of the upright graphene heterojunction.

[0021] Furthermore, the upright graphene resonant ring can induce a plasmon effect through geometric curvature, so that the light field energy is localized at the interface between the graphene resonant ring and the substrate, thereby optimizing the carrier transmission path, reducing the probability of carrier recombination while reducing the dark current and noise current in the photodetector, thereby improving the infrared light detection capability of the upright graphene heterojunction.

[0022] In summary, the upright graphene heterojunction of the present invention can further improve its photoelectric detection performance on the basis of reducing the upright graphene content, thereby achieving a balance between lightweight and detection capabilities of the upright graphene heterojunction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the planar structure of the upright graphene heterojunction in Example 1 of the present invention;

[0024] Figure 2This is an optical microscope image of the upright graphene heterojunction in Example 1 of the present invention;

[0025] Figure 3 Schematic diagram of the planar structure of the upright graphene heterojunction in Comparative Example 1 of the present invention;

[0026] Figure 4 Schematic diagram of the planar structure of the upright graphene heterojunction in Comparative Example 2 of the present invention;

[0027] Figure 5 The volt-ampere characteristic curves of the photodetector in Example 1 of the present invention under different wavelengths of light (the light power is uniformly 10mW / cm 2 );

[0028] Figure 6 The volt-ampere characteristic curves of the photodetectors in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention under 1550nm light;

[0029] Figure 7 is the frequency-dependent noise current of the photodetector in Example 1 of the present invention and Comparative Example 1;

[0030] Figure 8 1 is the photocurrent response curve of the photodetector in Example 1 of the present invention and Comparative Example 1;

[0031] Figure 9 The volt-ampere characteristic curves of the photodetector in Example 1 of the present invention under 1550nm light of different powers;

[0032] Figure 10 is a function curve between the photocurrent of the photodetector under 1550 nm light and the 1550 nm light power density in Example 1 of the present invention;

[0033] Figure 11 is the Raman spectrum of the upright graphene heterojunction in Example 1 of the present invention;

[0034] Figure 12 Response curve of the photodetector in Example 1 of the present invention to the change of optical power density of 1550nm wavelength light under 0V bias;

[0035] Figure 13 1 is the light response curve of the photodetector at different switching frequencies in Example 1 of the present invention;

[0036] Figure 14 : is the photocurrent decay curve of the photodetector at different switching frequencies in Example 1 of the present invention;

[0037] Figure 15 Graph showing the optical response of the photodetector in Example 1 of the present invention under 250 switching cycles;

[0038] Figure 16 is the coded output signal of the photodetector in Example 1 of the present invention;

[0039] Figure 17 is a normalized electric field distribution diagram of the upright graphene heterojunction in Example 1 of the present invention;

[0040] Figure 18 is a normalized power loss density distribution diagram of the upright graphene heterojunction in Example 1 of the present invention;

[0041] Figure 19 is a SEM image of the upright graphene heterojunction in Example 1 of the present invention;

[0042] Figure 20 This is an AFM image of the upright graphene heterojunction in Example 1 of the present invention.

[0043] 1. Substrate; 2. Upright graphene resonant ring; 21. Avoidance gap; 201. First upright graphene resonant ring; 202. Second upright graphene resonant ring; 203. Third upright graphene resonant ring; 204. Fourth upright graphene resonant ring; 205. Upright graphene wafer. DETAILED DESCRIPTION

[0044] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0045] Example 1:

[0046] like Figure 1 As shown, this embodiment first provides a vertical graphene heterojunction, which specifically includes a substrate 1 and a vertical graphene layer. The vertical graphene layer includes at least two vertical graphene resonant rings 2 arranged on the substrate 1, and the vertical graphene resonant rings 2 are arranged in sequence from the inside to the outside.

[0047] The shape of the upright graphene resonant ring 2 is not limited to a circular ring, and may also be an elliptical ring or other annular shape. In this embodiment, all upright graphene resonant rings 2 are circular and concentrically arranged. In other embodiments, different upright graphene resonant rings 2 may have different shapes, for example, some upright graphene resonant rings 2 may be circular, while other upright graphene resonant rings 2 may be elliptical.

[0048] This embodiment further provides a method for preparing the upright graphene heterojunction, comprising the following steps:

[0049] Step 101: Hollow out a relief opening on the mask plate that matches the designed shape of the upright graphene layer.

[0050] Specifically, in this embodiment, the substrate 1 for the upright graphene heterojunction is a silicon wafer; in other words, the material of substrate 1 is Si. The mask plate is a 0.3mm thick stainless steel plate. Since substrate 1 measures 1cm x 1cm, the mask plate must first be cut to 1cm x 1cm to match the shape of substrate 1. Laser cutting is then used to create a relief opening in the mask plate that matches the designed shape of the upright graphene layer.

[0051] Step 102: After the mask is placed on the substrate 1, it is transferred into a quartz tube along with the substrate 1 to grow upright graphene.

[0052] In this embodiment, step 102 specifically includes step 102a, step 102b and step 102c.

[0053] Step 102a: First, the quartz tube is evacuated to below 1 Pa, and then the temperature is raised to 550° C. at a heating rate of 10° C. / min. During the heating process, 10 sccm of argon and 1 sccm of hydrogen are continuously introduced as protective gases.

[0054] Step 102b: After the temperature is raised to 550° C., the introduction of argon and hydrogen is turned off, and the system is evacuated again to below 1 Pa.

[0055] Step 102c: After step 102b, 8 sccm of methane was continuously introduced as a carbon precursor, maintaining the pressure within the quartz tube between 10 Pa and 30 Pa. The plasma source was activated, and the RF power was set to 200 W to initiate growth of upright graphene within the avoidance opening. After 60 minutes of growth, the plasma source, heating source, and methane source were turned off, and 10 sccm of argon was continuously introduced, followed by cooling to room temperature.

[0056] It is particularly noteworthy that since upright graphene cannot grow on the surface of the stainless steel mask plate, the growth range of upright graphene is limited to the avoidance port. The upright graphene grown in the avoidance port eventually forms an upright graphene layer, so the final shape of the upright graphene layer is consistent with the shape of the avoidance port.

[0057] Step 103: After taking out the substrate 1, the mask is removed to obtain the upright graphene heterojunction.

[0058] Also, since upright graphene cannot grow on the surface of stainless steel, the upright graphene in the avoidance port will not adhere to the side walls of the avoidance port. Accordingly, when the mask plate is removed, the side walls of the avoidance port will not cause excessive damage to the upright graphene, thereby ensuring the shape integrity of the upright graphene layer.

[0059] The optical microscope image of the upright graphene heterojunction prepared in this example is as follows: Figure 2 As shown, it is not difficult to see that the edges of the upright graphene layer are clear and highly consistent with the designed shape of the upright graphene layer, which further confirms the feasibility and reliability of the method of preparing the upright graphene layer using a mask plate.

[0060] It is particularly important to note that in step 102c, since the mask plate is made of stainless steel, the recrystallization temperature of the mask plate can be higher than the growth temperature of the upright graphene. Therefore, during the growth of the upright graphene, less ions are precipitated in the mask plate, thereby reducing or avoiding the introduction of impurities during the growth of the upright graphene.

[0061] On the other hand, the use of stainless steel for the mask plate further requires that the flow rate of hydrogen gas flowing into the quartz tube in step 102a be effectively controlled. Typically, the hydrogen flow rate is not limited to the 1 sccm in this embodiment; in other embodiments, it can be appropriately relaxed to 0.5 sccm-2 sccm. The flow ratio of hydrogen to argon can be maintained at, for example, 1:10.

[0062] Specifically, if the hydrogen flow rate is too low, the natural oxide layer and attached organic matter on the surface of substrate 1 cannot be effectively removed. If the hydrogen flow rate is too high, it will over-react with the mask and substrate 1. Excessive hydrogen reaction with substrate 1 will cause a rough and porous structure to form on the surface of substrate 1, disrupting the interface between substrate 1 and the upright graphene in step 102c. Excessive hydrogen reaction with the mask will cause iron and chromium ions to precipitate within the mask, affecting the initial growth of upright graphene in step 102c.

[0063] The use of stainless steel for the mask plate not only limits the hydrogen flow rate but also the growth temperature of the upright graphene. In this embodiment, the growth temperature of the upright graphene is 550°C. In other embodiments, the growth temperature of the upright graphene can be relaxed to 500°C-600°C.

[0064] Specifically, if the growth temperature of upright graphene is lower than 500°C, the decomposition rate of methane and the activity of carbon atoms are insufficient, which in turn leads to insufficient growth rate or failure of upright graphene. If the growth temperature of upright graphene is higher than 600°C, on the one hand, it will cause changes in the structure of the silicon substrate 1, affecting the performance of the final upright graphene heterojunction. On the other hand, it will also damage the stainless steel mask plate, prompting the precipitation of ions in the mask plate, affecting the growth of upright graphene and causing an increase in impurities in the upright graphene. In addition, if the growth temperature is higher than 600°C, it will also lead to disordered deposition of carbon atoms, generating a large amount of amorphous carbon impurities, and reducing the quality of the upright graphene.

[0065] See again Figure 1 Preferably, in this embodiment, the upright graphene resonant ring 2 is provided with an avoidance gap 21. In other words, the upright graphene resonant ring 2 in this embodiment is not a complete circular ring, but a C-shaped structure.

[0066] If the upright graphene resonant ring 2 is a complete circular ring, then after the mask plate is hollowed out in step 101, a disc and several concentric rings will be obtained, and the disc and concentric rings are separated from each other and cannot be directly connected. Therefore, during the process of transferring the mask plate to the substrate 1, the disc and concentric rings need to be additionally aligned to re-set the disc and concentric rings concentrically. If the alignment accuracy is insufficient, it will cause a large deviation between the actual shape of the final upright graphene layer and the designed shape, affecting the concentricity between the different upright graphene resonant rings 2 finally prepared, thereby reducing the performance of the final upright graphene heterojunction.

[0067] In this embodiment, the avoidance gap 21 is provided on the upright graphene resonant ring 2 to avoid the separation of the above-mentioned disc and the concentric rings during the hollowing process of the mask plate, thereby ensuring that the shape of the final upright graphene layer actually prepared is highly consistent with the designed shape.

[0068] Further preferably, in this embodiment, there are four upright graphene resonance rings 2, which are, from the inside to the outside, a first upright graphene resonance ring 201, a second upright graphene resonance ring 202, a third upright graphene resonance ring 203 and a fourth upright graphene resonance ring 204.

[0069] Illustratively, the avoidance gap 21 of the fourth upright graphene resonant ring 204 , the avoidance gap 21 of the second upright graphene resonant ring 202 , the avoidance gap 21 of the first upright graphene resonant ring 201 , and the avoidance gap 21 of the third upright graphene resonant ring 203 are sequentially arranged in a straight line.

[0070] The upright graphene layer of this embodiment further includes a plurality of first upright graphene connecting wires 3 and second upright graphene connecting wires 4. The two ends of the first upright graphene connecting wires 3 are respectively located on two different upright graphene resonant rings 2, thereby connecting the two different upright graphene resonant rings 2 in series. One end of the second upright graphene connecting wire 4 is located on the upright graphene resonant ring 2, and the other end is used to electrically connect to an external electrode.

[0071] Specifically in this embodiment, there are two first upright graphene connecting lines 3 and two second upright graphene connecting lines 4 .

[0072] One of the second upright graphene connecting lines 4 is located at the avoidance gap 21 of the fourth upright graphene resonant ring 204 and is spaced apart from the fourth upright graphene resonant ring 204. One end of the second upright graphene connecting line 4 is located on the third upright graphene resonant ring 203, and the other end is located outside the fourth upright graphene resonant ring 204. Another second upright graphene connecting line 4 has one end located on the fourth upright graphene resonant ring 204, and the other end is located outside the fourth upright graphene resonant ring 204.

[0073] One of the first upright graphene connecting lines 3 is located at the avoidance notch 21 of the second upright graphene resonant ring 202 and is spaced apart from the second upright graphene resonant ring 202. The two ends of the first upright graphene connecting line 3 are respectively located on the third upright graphene resonant ring 203 and the first upright graphene resonant ring 201. Another first upright graphene connecting line 3 is located at the avoidance notch 21 of the third upright graphene resonant ring 203 and is spaced apart from the third upright graphene resonant ring 203. The two ends of the first upright graphene connecting line 3 are respectively located on the second upright graphene resonant ring 202 and the fourth upright graphene resonant ring 204.

[0074] With such a design, the first upright graphene resonant ring 201 and the third upright graphene resonant ring 203 can be mutually conductive within the upright graphene layer and electrically connected to one of the second upright graphene connection lines 4. At the same time, the second upright graphene resonant ring 202 and the fourth upright graphene resonant ring 204 can be mutually conductive within the upright graphene layer and electrically connected to another second upright graphene connection line 4.

[0075] It is particularly noteworthy that in this embodiment, the first upright graphene resonant ring 201 and the third upright graphene resonant ring 203 are disconnected from the second upright graphene resonant ring 202 and the fourth upright graphene resonant ring 204 inside the upright graphene layer, that is, they cannot be connected through the first upright graphene connecting line 3 and the second upright graphene connecting line 4.

[0076] In some other embodiments, a portion of the upright graphene resonant ring 2 and another portion of the upright graphene resonant ring 2 can also be kept in a disconnected state inside the upright graphene layer.

[0077] For example, in this embodiment, the outer edge radius of the fourth upright graphene resonant ring 204 is 4250 nm, the radial width of all upright graphene resonant rings 2 is uniformly about 450 nm, and the thickness of all upright graphene resonant rings 2 is uniformly about 1 μm.

[0078] Furthermore, this embodiment also provides a photodetector, comprising a power supply and a standing graphene heterojunction, wherein the standing graphene layer is connected to the positive electrode of the power supply, and the substrate 1 is connected to the negative electrode of the power supply.

[0079] More specifically, in this embodiment, the two second upright graphene connecting lines 4 are connected to the positive electrode of the power supply in parallel through a wire.

[0080] Comparative Example 1:

[0081] like Figure 3 As shown, this comparative example also provides a vertical graphene heterojunction, specifically comprising a substrate 1 and a vertical graphene layer. The growth conditions of the vertical graphene layer are the same as those in Example 1, and will not be repeated in this comparative example.

[0082] Unlike Example 1, the upright graphene layer in this comparative example includes an upright graphene disc 205 and a second upright graphene connecting line 4, but does not include an upright graphene resonant ring 2. The end of the second upright graphene connecting line 4 is located at the edge of the upright graphene disc 205. The upright graphene disc 205 has a radius of 4250 nm and a thickness of approximately 1 μm.

[0083] This comparative embodiment further provides a photodetector, comprising a power supply and an upright graphene heterojunction, wherein the second upright graphene connection line 4 is connected to the positive electrode of the power supply, and the substrate 1 is connected to the negative electrode of the power supply.

[0084] Comparative Example 2:

[0085] like Figure 4 As shown, this comparative example also provides a vertical graphene heterojunction, specifically comprising a substrate 1 and a vertical graphene layer. The growth conditions of the vertical graphene layer are the same as those in Example 1, and will not be repeated in this comparative example.

[0086] Unlike Example 1, the upright graphene layer in this comparative example only includes a fourth upright graphene resonant ring 204 and a second upright graphene connecting line 4. The end of the second upright graphene connecting line 4 is located at the outer edge of the fourth upright graphene resonant ring 204. In this comparative example, the outer edge radius of the fourth upright graphene resonant ring 204 is 4250 nm, the radial width is approximately 450 nm, and the thickness is approximately 1 μm.

[0087] This comparative embodiment further provides a photodetector, comprising a power supply and an upright graphene heterojunction, wherein the second upright graphene connection line 4 is connected to the positive electrode of the power supply, and the substrate 1 is connected to the negative electrode of the power supply.

[0088] like Figure 5 As shown, when the upright graphene layer in Example 1 was illuminated by light of 380 nm, 440 nm, 520 nm, 780 nm, 980 nm, and 1550 nm, corresponding photocurrents were generated in the photodetector. This proves that the detection range of the photodetector in Example 1 covers 380 nm-1550 nm and can be used for infrared detection.

[0089] The spot diameter is 40 μm, the wavelength is 1550 nm, and the power is 20 mW / cm 2 The light beams were irradiated on the upright graphene layers in Example 1, Comparative Example 1 and Comparative Example 2, and the obtained volt-ampere characteristic curves were as follows: Figure 6 As shown, the bias voltage is -3V. Figure 6 The specific data corresponding to each volt-ampere characteristic curve are shown in Table 1. , , P is the light power density (20 mW / cm 2 ), S is the effective illumination area (area of ​​a light spot with a diameter of 40 μm).

[0090] Table 1

[0091]

[0092] like Figure 6 As shown in Table 1, the responsivity R and specific detectivity D* of the photodetector in Example 1 are significantly better than those of the photodetectors in Comparative Example 1 and Comparative Example 2. In addition, it can be found that the responsivity of the photodetector in Comparative Example 2 is significantly lower than that of the photodetector in Comparative Example 1, which shows that a single upright graphene resonant ring 2 cannot guarantee an improvement in the detection capability of the photodetector. In other words, the number of upright graphene resonant rings 2 must be at least two.

[0093] On the other hand, when the number of upright graphene resonant rings 2 exceeds four, the electric field in the upright graphene layer will tend to disperse and interference cancellation will occur, which will cause the performance of the photodetector to deteriorate and gradually approach that of Comparative Example 1. This shows that the number of upright graphene resonant rings 2 contained in the upright graphene layer should preferably be 2-4.

[0094] Moreover, in order to better realize infrared detection, the radial spacing d between the two adjacent upright graphene resonant rings 2 in Example 1 should not be too large or too small. In some other embodiments, the value range of d can be relaxed to 155nm-465nm. If d is less than 155nm, the electric field coupling between the two adjacent upright graphene resonant rings 2 is too strong, resulting in higher losses, causing the light response to be unclear, thereby causing the performance of the photodetector to decline and gradually approach the comparative example 1. If d>465nm, the coupling between the two adjacent upright graphene resonant rings 2 is weak, thereby causing the performance of the photodetector to decline and gradually approach the comparative example 2.

[0095] It is not difficult to find that not only does the photodetector performance of Example 1 outperform that of Comparative Example 1, but the content of upright graphene in the photodetector is also lower than that of Comparative Example 1. It is understandable that generally, the lower the content of upright graphene, the worse the performance of the photodetector. However, the photodetector in Example 1 clearly overcomes this technical bias.

[0096] like Figure 7 As shown, the photodetector of Example 1 has lower dark current and noise current than that of Comparative Example 1, which shows that the upright graphene heterojunction of Example 1 has a better charge transfer path and reduces the recombination of electron-hole pairs.

[0097] like Figure 8 As shown, under 1550nm illumination and a switching frequency of 1000Hz, the photocurrent rise time and fall time of Example 1 are 267μs and 260μs, respectively, which are significantly lower than the 286μs rise time and 271μs fall time in Comparative Example 1. This is due to the shape design of the upright graphene resonant ring 2, which optimizes the charge transfer path and improves the local electric field within the ring, thereby increasing the mobility of photogenerated carriers, enabling faster carrier separation and transmission, and shortening the response time of the photodetector.

[0098] like Figure 9 and Figure 10 As shown, for the photodetector in Example 1, the increase in light power density will cause more photogenerated carriers to pass through the barrier, thereby increasing the photocurrent, and the light power density is 25mW / cm 2 -125mW / cm 2 Within this range, the photocurrent Iph There is a good linear relationship between the power of the optical power density P and 0.9, which proves that even under high light intensity, the photodetector in Example 1 still has good carrier separation efficiency, and also proves that the photodetector in Example 1 has good thermal stability.

[0099] The Raman spectrum of the upright graphene heterojunction in Example 1 is as follows: Figure 11 As shown, we can see that the Si in substrate 1 has a 520 cm -1 peak, and the D peak of upright graphene (1350 cm -1 )、G peak(1580 cm -1 ), D' peak (1610 cm -1 ) and 2D peak (2700 cm -1 Because upright graphene has a large number of exposed edges, it exhibits a more pronounced D peak and a unique D' peak compared to two-dimensional graphene. The high density of edge defects can serve as active sites for carrier transport and induce light scattering, extending carrier lifetime and further increasing optical path length. Figure 11 The inset in Figure 1 shows the water contact angles before and after the standing graphene layer is deposited on substrate 1. In this example, the standing graphene layer exhibits superhydrophobicity (contact angle 135°), while Si exhibits hydrophilicity (contact angle 60°). This demonstrates that the standing graphene heterojunction can effectively suppress water adsorption in the environment and improve the stability of the photodetector.

[0100] like Figure 12 As shown, the bias voltage is 0V, and the photodetector in Example 1 is illuminated by light of 1550nm wavelength. As the light power density increases from 50 W / cm 2 Increased to 100 W / cm 2 Then reduce to 50 W / cm 2 During the process, the photocurrent of the photodetector first increases and then decreases, showing strong reversibility, which proves that the photodetector in Example 1 has good self-power supply capability and response stability.

[0101] like Figure 13 As shown, when the photodetector in Example 1 is illuminated by light of 1550nm wavelength, the switching frequencies are 250Hz, 500Hz and 1000Hz respectively, and the fast response characteristics are maintained, and the waveform is complete, which proves that the photodetector can stably perform repeated detection of high-frequency optical signals. Figure 14 , the 3dB cut-off frequency of the switching frequency is 1300Hz, which further confirms the above conclusion.

[0102] like Figure 15As shown, the photodetector in Example 1 is irradiated with light of 1550 nm wavelength and the switching frequency is 10 Hz. Within 250 switching cycles, the peak value of the photocurrent remains stable without fatigue or degradation. Figure 15 The illustration shows that the device output waveform is highly consistent within 10 switching cycles, further verifying the high stability of the device under repetitive operating conditions.

[0103] like Figure 16 As shown, the "Beyond" ASCII signal is encoded with a 1550nm laser, and the photodetector in Example 1 can well convert it back into an electrical pulse signal, proving that it can be used for infrared communication.

[0104] The excellent performance of the photodetector and the upright graphene heterojunction in Example 1 mainly depends on the shape design of the upright graphene layer, the upright graphene morphology characteristics and the synergistic effect between the two.

[0105] To confirm the above conclusion, we can first refer to Figure 17 and Figure 18 .in Figure 17 and Figure 18 The method for obtaining is as follows: Finite-difference time-domain (FDTD) simulations were used to calculate the normalized electric field and power loss density distribution of the upright graphene heterojunction in Example 1, assuming a light source wavelength of 1550 nm, a refractive index of 2.6 + 1.3i (i is an imaginary unit), a refractive index of substrate 1 of 4.1, and normal incidence of light on the upright graphene layer. In the FDTD simulations, the Lorentz-Druze model was used as the dielectric function, with its parameters matching the refractive indices of substrate 1 and the upright graphene layer.

[0106] Figure 17 It shows that the upright graphene layer in Example 1 exhibits a significant local enhancement effect of the electric field, and the surface plasmon resonance at the local enhancement position can effectively focus the 1550 nm wavelength light field. Figure 18 It shows that the energy dissipation of the upright graphene layer in Example 1 is mainly concentrated at the curved edge of the upright graphene resonant ring 2, which is different from the Figure 17 The electric field enhancement region is highly consistent, which proves that the localized surface plasmon resonance induced by the curved structure of the upright graphene resonant ring 2 can effectively enhance the interaction between the light field and the upright graphene layer.

[0107] based on Figure 17 and Figure 18The following conclusions can be further drawn: the upright graphene resonant ring 2 can induce a plasmon effect through geometric curvature, causing the light field energy to be localized at the interface between the graphene resonant ring 2 and the substrate 1, thereby optimizing the carrier transmission path, reducing the probability of carrier recombination, and reducing the dark current and noise current in the photodetector. In addition, the avoidance gap 21 on the upright graphene resonant ring 2 can further effectively serve as an energy input / output interface, providing a coupling channel for the incident light. If the avoidance gap 21 is removed, the effective coupling path of the incident light may be blocked, reducing the energy residence time and absorption rate within the upright graphene layer.

[0108] Furthermore, if all upright graphene resonant rings 2 are connected in pairs within the upright graphene layer, the charge transfer path becomes complicated and may even form a circulating current, which is not conducive to building a fast, low-noise Schottky barrier. In Example 1, however, since the first upright graphene resonant ring 201 and the third upright graphene resonant ring 203 are disconnected from the second upright graphene resonant ring 202 and the fourth upright graphene resonant ring 204 within the upright graphene layer, an effective carrier collection path can be formed, suppressing the effects of parasitic capacitance and inductance caused by the redundant structure.

[0109] Further Figure 19 and Figure 20 As shown in Figure 2, the nanoscale pores and voids between the layers of upright graphene form a resonant cavity, increasing the specific surface area of ​​the upright graphene layer. This in turn induces multiple reflections and scattering of photons, increasing the optical path and promoting light absorption. Furthermore, the coupling interface between the upright graphene and silicon is free of obvious faults, indicating a high-quality coupling interface. This helps reduce charge recombination at the interface and improves interfacial transfer efficiency. Furthermore, the upright graphene provides a longitudinal charge transfer path, reducing the probability of recombination between photogenerated electron-hole pairs and improving charge collection efficiency.

[0110] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0111] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A photoelectric detector, characterized in that: The invention comprises a power supply and an upright graphene heterojunction, wherein the upright graphene heterojunction comprises a substrate (1) and an upright graphene layer, wherein the upright graphene layer is connected to the positive electrode of the power supply, and the substrate (1) is connected to the negative electrode of the power supply, wherein the upright graphene layer comprises at least two upright graphene resonant rings (2) arranged on the substrate (1), wherein the upright graphene resonant rings (2) are arranged in sequence from the inside to the outside, and an avoidance gap (21) is provided on the upright graphene resonant rings (2), and wherein the upright graphene layer comprises a first upright graphene connecting line (3), wherein both ends of the first upright graphene connecting line (3) are respectively located on the two upright graphene resonant rings (2), and a part of the upright graphene resonant rings (2) and another part of the upright graphene resonant rings (2) are disconnected and arranged in the upright graphene layer.

2. The photodetector according to claim 1, wherein The number of the upright graphene resonant rings (2) is two, three or four.

3. The photodetector according to claim 1, wherein The distance between two adjacent upright graphene resonant rings (2) is 155nm-465nm.

4. The photodetector according to claim 1, 2 or 3, wherein: The preparation method of the upright graphene heterojunction comprises: Hollowing out a relief opening on the mask plate that matches the designed shape of the upright graphene layer; The mask is placed on the substrate and then the upright graphene layer is grown.

5. The photodetector according to claim 4, wherein: The preparation method of the upright graphene heterojunction further includes: The mask plate and substrate are transferred into a quartz tube, evacuated, and then heated. Hydrogen is continuously introduced during the heating process, wherein the flow rate of hydrogen is 0.5 sccm-2 sccm. The material of the mask plate is stainless steel.

6. The photodetector according to claim 4, wherein: The growth temperature of the upright graphene layer is 500° C.-600° C., and the mask plate is made of stainless steel.

7. Use of the photoelectric detector according to any one of claims 1 to 6 in infrared signal transmission.

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