Vertical photoconductive switch and preparation method thereof

Abstract

The invention discloses a vertical photoconductive switch and a preparation method thereof, and belongs to the technical field of semiconductors, and the vertical photoconductive switch comprises a substrate, an upper surface electrode disposed on the upper surface of the substrate, and a lower surface electrode disposed on the lower surface of the substrate. The projection of the upper surface electrode on the substrate and the projection of the lower surface electrode on the substrate do not completely coincide, and the upper surface electrode and the lower surface electrode are both of an asymmetric structure. An electric field vector generated by the upper surface electrode and an electric field vector generated by the lower surface electrode are subjected to interference superposition in different directions to form a staggered electric field. According to the vertical photoconductive switch, the upper electrode and the lower electrode which are of an asymmetric structure are adopted, so that current is uniformly diffused in the radial direction and the vertical direction, overdense local current, incomplete superposition of projections of the upper electrode and the lower electrode and breaking of symmetry of an electric field are avoided, the local electric field intensity is effectively reduced, and the overall voltage endurance capability of a device is improved.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor technology, and more particularly, relates to a vertical photoconductive switch and a preparation method thereof. Background Art

[0002] Gallium nitride (GaN), a representative material of third-generation semiconductors, possesses exceptional physical and chemical properties, making it an ideal choice for high-frequency, high-power, and optoelectronic devices. This provides the material foundation for the reliability of photoconductive switches under extreme operating conditions. Photoconductive switches are semiconductor switching devices that are triggered by lasers of a specific wavelength. They offer advantages such as small size, low energy consumption, high output power, fast response speed, and high repetition rate. They hold broad application prospects in high-end fields such as medicine, military, and aerospace. Depending on the device structure, photoconductive switches are primarily categorized as vertical and planar. The vertical structure is more suitable for high-voltage, high-current environments.

[0003] The main structure of a vertical photoconductive switch consists of a substrate and electrodes arranged on either side of the substrate. In existing technology, the two electrodes are typically mounted symmetrically on either side of the substrate, typically in a circular or rounded rectangular configuration. Other structures are then introduced to improve device performance. Common approaches include: using insulating materials on the upper and lower surfaces of the substrate to reduce the electric field strength at the electrode edges; or, creating concentric ring-shaped grooves of varying diameters around the electrodes, topped with a passivation layer to extend the electrode's distance from the wafer edge and reduce the field strength at the electrode edges; or, applying a dense insulating oxide layer around the electrodes.

[0004] Existing vertical photoconductive switches suffer from the following drawbacks: First, the current density is unevenly distributed, with the current often concentrated in the center of the device or in specific channels, leading to severe localized heating and prone to thermal breakdown. Second, the electric field is concentrated, increasing the risk of breakdown. Symmetrical or point-shaped electrodes make it difficult to effectively control the electric field distribution, leading to electric field peaks at edges or contact areas, reducing the device's withstand voltage. Therefore, addressing the current concentration, localized overheating, and insufficient withstand voltage issues inherent in existing vertical photoconductive switches is of great research significance. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides a vertical photoconductive switch and a method for preparing the same, which aims to solve the problems of current concentration, local overheating and insufficient voltage resistance in the prior art vertical photoconductive switches.

[0006] According to one aspect of the present invention, a vertical photoconductive switch is provided, comprising: a substrate, an upper surface electrode arranged on the upper surface of the substrate, and a lower surface electrode arranged on the lower surface of the substrate; the projection of the upper surface electrode on the substrate does not completely overlap with the projection of the lower surface electrode on the substrate, and both the upper surface electrode and the lower surface electrode have asymmetric structures; the electric field vector generated by the upper surface electrode and the electric field vector generated by the lower surface electrode interfere and superimpose in different orientations to form an interlaced electric field.

[0007] Preferably, the upper surface electrode and the lower surface electrode include: a spiral electrode, a curved staggered electrode and a radial grid electrode; and the upper surface electrode and the lower surface electrode are the same electrode.

[0008] Preferably, the upper surface electrode and the lower surface electrode are both spiral electrodes; the upper surface electrode and the lower surface electrode rotate in opposite directions, and the current flowing into the upper surface electrode has the same direction as the current flowing into the lower surface electrode.

[0009] Preferably, the projection of the upper surface electrode on the substrate and the projection of the lower surface electrode on the substrate are concentrically nested with each other.

[0010] Preferably, the upper surface electrode and the lower surface electrode are both spiral electrodes; the upper surface electrode and the lower surface electrode have the same rotation direction, and the projection of the upper surface electrode on the substrate is not concentric with the projection of the lower surface electrode on the substrate, and the current passed through the upper surface electrode is opposite to the direction of the current passed through the lower surface electrode.

[0011] Preferably, the distance between the projection of the center of the upper surface electrode on the substrate and the projection of the center of the lower surface electrode on the substrate is 300-800 μm.

[0012] Preferably, the electrode line width of the spiral electrode is 100-200 μm; and / or the pitch of the spiral electrode is 400-800 μm.

[0013] Preferably, the outer diameter of the spiral electrode is 5-8 mm; and / or the inner diameter of the spiral electrode is 2.5-4 mm.

[0014] Preferably, the material of the substrate includes semi-insulating iron-doped gallium nitride single crystal material, and the vertical photoconductive switch includes a vertical gallium nitride photoconductive switch.

[0015] According to one aspect of the present invention, a method for preparing a vertical photoconductive switch is provided, which is used to prepare the vertical photoconductive switch as described above, and the preparation method includes: providing a substrate; preparing an upper surface electrode on the upper surface of the substrate; and preparing a lower surface electrode on the lower surface of the substrate; wherein the projection of the upper surface electrode on the substrate does not completely overlap with the projection of the lower surface electrode on the substrate, and the upper surface electrode and the lower surface electrode are both asymmetric structures; the electric field vector generated by the upper surface electrode and the electric field vector generated by the lower surface electrode interfere and superimpose in different directions to form an interlaced electric field.

[0016] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects: a vertical photoconductive switch is provided, in which the projection of the upper surface electrode on the substrate does not completely overlap with the projection of the lower surface electrode on the substrate, and both the upper surface electrode and the lower surface electrode are asymmetric structures; the electric field vector generated by the upper surface electrode and the electric field vector generated by the lower surface electrode interfere and superimpose in different directions to form an interlaced electric field, breaking the central electric field superposition and edge field strength concentration phenomenon, breaking the electric field symmetry, effectively reducing the local electric field strength, making full use of the advantages of the substrate, and improving the overall voltage resistance of the device; the electrode adopts an asymmetric structure, and the asymmetric pattern makes the current extend a longer path in the plane, and is "twisted and diffused" before entering the lower electrode, forming a larger power consumption area and a smaller unit heat accumulation, avoiding local current over-density, and improving device reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A front view of a vertical light guide switch provided by an embodiment of the present invention; Figure 2 A top view of a vertical light guide switch provided by one embodiment of the present invention; Figure 3 for Figure 2 A top view of the upper surface electrode in the vertical photoconductive switch; Figure 4 for Figure 2 A top view of the lower surface electrode in the vertical photoconductive switch shown; Figure 5 、 Figure 6 、 Figure 7 The electric field intensity distribution simulation diagrams of the planar structure photoconductive switch, the traditional vertical structure photoconductive switch, and the vertical photoconductive switch of the present invention under bias voltage conditions are shown respectively; Figure 8 、 Figure 9 、 Figure 10 Comparison diagrams of current expansion paths under bias voltage conditions for a planar structure photoconductive switch, a conventional vertical structure photoconductive switch, and the vertical photoconductive switch of the present invention; Figure 11A comparison chart of the breakdown voltage of photoconductive switches with different structures.

[0018] Explanation of reference numerals: 1 is a substrate, 2 is an upper surface electrode, 3 is a lower surface electrode, and 4 is an incident laser. DETAILED DESCRIPTION

[0019] In view of the shortcomings of the prior art, the inventors of this case, after long-term research and extensive practice, have proposed the technical solution of the present invention. The following will further explain this technical solution, its implementation process and principles.

[0020] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0021] In addition, in the description of the present invention, it should be understood that the terms "upper", "lower", "inside", "outside", "horizontal", "vertical", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0022] Throughout this specification, references to "one embodiment," "an embodiment," "the embodiment," and the like indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. Throughout this specification, the schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0023] The first aspect of the present invention provides a vertical photoconductive switch. Figure 1 , comprising: a substrate 1, an upper surface electrode 2 disposed on the upper surface of substrate 1, and a lower surface electrode 3 disposed on the lower surface of substrate 1. The projection of the upper surface electrode 2 on substrate 1 does not completely overlap with the projection of the lower surface electrode 3 on substrate 1, and both the upper surface electrode 2 and the lower surface electrode 3 have an asymmetric structure. The electric field vectors generated by the upper surface electrode and the electric field vectors generated by the lower surface electrode interfere and superimpose in different directions, forming an interlaced electric field.

[0024] The projection of the upper surface electrode 2 on the substrate 1 does not completely overlap with the projection of the lower surface electrode 3 on the substrate 1 . Here, the incomplete overlap means that the projections of the two do not overlap or partially overlap. The incident laser 4 is incident from the side of the substrate 1 .

[0025] In the vertical photoconductive switch provided by the embodiment of the present invention, both the upper and lower surface electrodes adopt an asymmetric structure, and the projections of the upper and lower surface electrodes on the substrate do not overlap, forming an asymmetric structure; on the one hand, the asymmetrically arranged electrode structure destroys the symmetry of the electric field, and can achieve a more uniform electric field and current distribution in the vertical direction, effectively regulating the electric field distribution, thereby reducing the peak electric field intensity, improving the anti-breakdown capability, reducing local heat accumulation, and effectively improving the stability and voltage resistance of the device under high voltage and high power working conditions. It is suitable for high voltage and high power energy storage converter applications, while improving the conductive uniformity, maintaining the switching response speed and current carrying capacity; on the other hand, the current is expanded simultaneously in the vertical direction and the radial direction, avoiding excessive current density concentrated in a certain central area, further enhancing the current expansion effect; on the other hand, the non-overlapping projections of the upper and lower surface electrodes on the substrate can avoid dislocations penetrating the upper and lower electrodes, which can further reduce the risk of device breakdown.

[0026] Preferably, the top and bottom electrodes include spiral electrodes, curved interlaced electrodes, and radial grid electrodes; and the top and bottom electrodes are the same type. For example, both the top and bottom electrodes may be spiral electrodes, curved interlaced electrodes, or radial grid electrodes. These specific electrode structures are consistent with the technical concepts of the present invention and can achieve the goals of breaking electric field concentration, expanding current paths, and optimizing heat distribution.

[0027] Curved interleaved electrodes utilize one or more electrodes arranged in a wavy, S-shaped, or arc-shaped pattern. The staggered arrangement of the upper and lower electrodes creates a staggered distribution or gradient transition zone within the device, breaking the electric field concentration along a single axis. The asymmetric arrangement of the wavy, S-shaped, or arc-shaped electrodes on the upper and lower surfaces enables multipath current diffusion in both vertical and horizontal directions, effectively reducing local current density.

[0028] The curved staggered electrodes have the following advantages: breaking the upper and lower symmetry and forming asymmetric electric field interference in the vertical direction; the current expands along the curved extension path to avoid excessive current density in the center; the manufacturing process is compatible with traditional masks and is suitable for lithography of more complex electrode patterns; it is particularly suitable for energy storage converters designed with linear laser irradiation or long strip photosensitive areas.

[0029] The radial grid electrode consists of multiple "radial electrode strips" radiating outward from the center or edge of the electrode, with the electrodes on the upper and lower surfaces arranged in a non-completely corresponding (i.e., asymmetrical) pattern. The electrodes can be solid strips or a grid structure, creating a non-uniform electric field strength distribution with significant regional variations. By arranging the electrode strips at non-uniform angles or lengths and staggering the upper and lower layers, a dispersed electric field distribution pattern is formed, further improving voltage resistance and thermal balance.

[0030] Radial grid electrodes have the following advantages: the gradient expansion of current density can be achieved by changing the spacing, width and angle of the radial strips; the upper and lower grids are staggered to avoid complete overlap of the electric field and increase the breakdown threshold; they are suitable for circular or polygonal device shapes, especially for large-area lighting applications; the high coverage of the grid structure is used to improve current conduction efficiency while dispersing hot spots.

[0031] In one embodiment of the present invention, both the upper surface electrode 2 and the lower surface electrode 3 are spiral electrodes; the upper surface electrode 2 and the lower surface electrode 3 rotate in opposite directions, and the current flowing into the upper surface electrode has the same direction as the current flowing into the lower surface electrode. Figure 3 As shown, the shape of the lower surface electrode is Figure 4 shown.

[0032] Further preferably, the projection of the upper surface electrode 2 on the substrate 1 and the projection of the lower surface electrode 3 on the substrate 1 are concentrically nested with each other, such as Figure 2 It should be noted that the projection of the upper surface electrode 2 on the substrate 1 and the projection of the lower surface electrode 3 on the substrate 1 may also be non-concentric.

[0033] In another embodiment of the present invention, both the upper surface electrode 2 and the lower surface electrode 3 are spiral electrodes; the upper surface electrode 2 and the lower surface electrode 3 rotate in the same direction, and the projection of the upper surface electrode 2 on the substrate 1 is not concentric with the projection of the lower surface electrode 3 on the substrate 1, and the current passing through the upper surface electrode is in the opposite direction to the current passing through the lower surface electrode. Further preferably, the distance between the projection of the center of the upper surface electrode on the substrate and the projection of the center of the lower surface electrode on the substrate is 300-800 μm. The distance between the projection of the center of the upper surface electrode on the substrate and the projection of the center of the lower surface electrode on the substrate is, for example, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm or 800 μm.

[0034] Preferably, both the upper surface electrode 2 and the lower surface electrode 3 are spiral electrodes, and the electrode line width of the spiral electrode is 100-200 μm; the pitch of the spiral electrode is 400-800 μm; the outer diameter of the spiral electrode is 5-8 mm; and the inner diameter of the spiral electrode is 2.5-4 mm. The electrode line width of the spiral electrode is, for example, 100 μm, 120 μm, 140 μm, 150 μm, 160 μm, 180 μm, or 200 μm; the pitch of the spiral electrode is, for example, 400 μm, 500 μm, 550 μm, 600 μm, 700 μm, or 800 μm; the outer diameter of the spiral electrode is, for example, 5 mm, 6 mm, 6.5 mm, 7 mm, or 8 mm; and the inner diameter of the spiral electrode is, for example, 2.5 mm, 3 mm, 3.5 mm, or 4 mm.

[0035] The spiral electrode structure used in the embodiments of the present invention has excellent current expansion capability and geometric scalability, and is suitable for the design and manufacture of large-area, high-voltage photoconductive switching devices. The current flows in a diffuse manner in the spiral path, forming a multi-path shunt, which not only effectively reduces the current density concentration phenomenon, but also significantly improves the local thermal management performance of the device. At the same time, the asymmetric arrangement between the upper and lower electrodes can break the electric field superposition effect caused by the traditional symmetrical structure, making the electric field distribution more uniform and further reducing the local electric field peak. In addition, the asymmetric spiral structure can prevent dislocations from penetrating the upper and lower electrodes, which can further reduce the risk of device breakdown.

[0036] Preferably, substrate 1 is made of a semi-insulating iron-doped gallium nitride single crystal material, and the vertical photoconductive switch comprises a vertical gallium nitride photoconductive switch. Semi-insulating iron-doped gallium nitride can serve as an electrical isolation layer between devices to increase the overall breakdown voltage, and can also serve as a substrate material for high-performance devices. It exhibits excellent performance in the photoconductive state (low on-resistance), dark state (low leakage current), and light-to-dark conversion (short carrier lifetime), making it one of the most promising semiconductor materials for high-frequency, high-power photoconductive switching.

[0037] The second aspect of the present invention provides a method for preparing a vertical photoconductive switch, which is used to prepare the above-mentioned vertical photoconductive switch, and the preparation method includes: providing a substrate; preparing an upper surface electrode on the upper surface of the substrate; preparing a lower surface electrode on the lower surface of the substrate; wherein the projection of the upper surface electrode on the substrate does not completely overlap with the projection of the lower surface electrode on the substrate, and the upper surface electrode and the lower surface electrode are both asymmetric structures; the electric field vector generated by the upper surface electrode and the electric field vector generated by the lower surface electrode interfere and superimpose in different directions to form an interlaced electric field.

[0038] Exemplarily, the specific process of the vertical photoconductive switch preparation method includes the following steps 1 to 8.

[0039] Step 1: Organic cleaning: Immerse the sample in acetone, isopropyl alcohol, and deionized water, washing for 5 minutes in each solution. Repeat two cycles to remove organic contaminants on the sample surface.

[0040] Step 2: Inorganic cleaning: Immerse the sample in a mixture of hydrochloric acid and deionized water at a volume ratio of 1:2 for 5 minutes to remove the oxide layer on the sample surface.

[0041] Step 3: Pattern transfer of the top surface electrode: Using standard photolithography processes (including coating, exposure, development, and hardening), the top surface electrode pattern is accurately transferred from the mask to the sample top surface.

[0042] Step 4: Deposit the top surface electrode. Use magnetron sputtering to sequentially deposit Ti / Al / Ti / Al multilayer metals (thicknesses of 20 nm / 130 nm / 50 nm / 50 nm) on the sample surface to form an ohmic contact electrode.

[0043] Step 5: Metal stripping: Immerse the sample in N-methylpyrrolidone (NMP) solution to dissolve the photoresist layer, selectively remove the metal in the non-patterned area, and retain the electrode pattern on the top surface.

[0044] Step 6: Transfer of bottom surface electrode pattern: After flipping the sample, repeat the standard photolithography process to transfer the bottom surface electrode pattern to the bottom surface of the sample.

[0045] Step 7: Deposit the bottom surface electrode. Use magnetron sputtering to sequentially deposit Ti / Al / Ti / Al multilayer metals (thicknesses of 20 nm / 130 nm / 50 nm / 50 nm) on the sample surface to form an ohmic contact electrode.

[0046] Step 8: Metal stripping: The sample is placed in NMP solution again to remove excess metal and complete the formation of the lower surface electrode pattern.

[0047] The structure of the vertical light-conductive switch prepared in the embodiment of the present invention is the same as that of the vertical light-conductive switch in the above embodiment, and will not be described in detail here.

[0048] The technical solution of the present invention is further described in detail below in conjunction with several preferred embodiments and the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The test methods in the following examples where specific conditions are not specified are generally based on conventional conditions.

[0049] by Figure 2 The structure shown is taken as an example to illustrate the vertical photoconductive switch in the embodiment of the present invention.

[0050] In the vertical photoconductive switch, the substrate material is semi-insulating Fe-doped GaN single crystal, the substrate thickness is about 550 μm, and the Fe doping concentration is about 5×10 18 cm -3 , the substrate resistivity at room temperature (300 K) is 1×10 8 Ω·cm, and the carrier concentration is 6.2×10 8 cm -3 The laser is incident from the side of the substrate, and GaN-based photoconductive switches are usually excited by 532 nm laser.

[0051] The top (Ga) surface electrode is formed by alternating layers of Ti / Al / Ti / Au, with thicknesses of 20 nm / 130 nm / 50 nm / 50 nm, and a spiral structure. The bottom (N) surface electrode is formed by alternating layers of Ti / Al / Ti / Au, with thicknesses of 20 nm / 130 nm / 50 nm / 50 nm, also in a spiral structure. When viewed from above, the top and bottom electrodes are concentrically nested, but with opposite rotational directions, and the patterns do not overlap, forming an asymmetric spiral electrode structure.

[0052] Figure 5 、 Figure 6 、 Figure 7 The figure shows the simulation results of the electric field intensity distribution of photoconductive switches with different structures under bias voltage conditions. Figure 5 is the electric field distribution diagram of the planar structure photoconductive switch, Figure 6 This is the electric field distribution diagram of the traditional vertical structure photoconductive switch. Figure 7 This is the electric field distribution diagram of the vertical asymmetric double-helix electrode structure photoconductive switch proposed by the present invention.

[0053] In order to verify the advantages of the structure of the present invention in electric field control, the electric field intensity distribution of the three different structures of the photoconductive switch devices was simulated by numerical simulation method. The results show that: Figure 5 In the planar structure shown, the peak electric field is mainly concentrated in the electrode edge area, with a maximum value of up to 1.88×10 5 V / cm, there is a significant risk of breakdown; Figure 6 In the traditional vertical structure shown in the figure, the upper and lower electrodes are arranged symmetrically, and the electric field is still concentrated in the edge area of ​​the electrodes, with a peak electric field of 1.48×10 5 V / cm, the local electric field is still high, which poses a certain safety hazard; Figure 7 In the structure of the present invention shown in FIG, an asymmetric double-helix electrode arrangement is adopted. By means of the difference in the rotation direction and pattern morphology, the electric field is effectively guided to expand uniformly in the vertical and radial directions, and the electric field is dispersed into multiple parts. The electric field peak is significantly suppressed, and the peak electric field is significantly reduced to 1.15×10 5 V / cm, which is about 29.29% lower than the traditional vertical structure and about 38.82% lower than the planar structure.

[0054] It can be seen that the present invention effectively breaks the symmetrical concentration effect of the electric field through the asymmetric electrode structure, reduces the local electric field strength and the risk of heat accumulation caused by it, and significantly improves the breakdown tolerance and thermal stability of the device under high voltage and high power working conditions, providing it with higher reliability guarantees in actual engineering applications.

[0055] Figure 8 、 Figure 9 、 Figure 10 The figure shows the simulation results of the current expansion path of photoconductive switches with different structures under bias voltage conditions. Figure 8 is the current expansion path of the planar structure photoconductive switch, Figure 9 It is the current expansion path of the traditional vertical structure photoconductive switch. Figure 10 This is the current expansion path of the vertical asymmetric double-helix electrode structure photoconductive switch proposed by the present invention.

[0056] See Figures 8-10 It can be seen that the current is highly concentrated in the planar structure, with a peak current density of 0.0121 A / cm 2 ; The vertical structure has improved, but the peak is still as high as 0.00781 A / cm 2 In the spiral structure of the present invention, the current expands along multiple radial paths, and the peak current density is significantly reduced to 0.00663 A / cm 2 , a 15.10% reduction compared to traditional vertical structures and a 45.21% reduction compared to planar structures. Simulation results show that this structure effectively suppresses local current density peaks, significantly reducing the risk of heat accumulation and electrical breakdown. This advantage fundamentally solves the thermal stability problem of existing structures in high-power energy storage converter applications.

[0057] It should be noted that the above Figures 8-10 The simulation results are derived from the simulation tool. Under the simulation conditions, normalized laser power, simplified electrode area and initial carrier concentration settings are used. The simulation results are mainly used to compare and analyze the current distribution trends and relative peak changes of different structures. Although the current density value in the simulation is 10 -2 ~10 -3 A / cm 2 This figure represents an order of magnitude, but it reflects the physical behavior of typical semi-insulating GaN materials under weak excitation conditions and does not represent the absolute current output during actual device operation. In experiments, under intense 532 nm laser excitation, actual currents reached levels exceeding μA, with current densities far exceeding simulation values. Therefore, the results in this figure are intended only to demonstrate the comparative advantages of the structural design in suppressing current path distribution and density peaks, and should not be used as a direct indicator of the device's on-current performance.

[0058] In order to further verify the voltage resistance performance of the structure of the present invention, the same materials and process conditions were used to prepare the planar structure, the traditional vertical structure and the asymmetric double spiral electrode structure photoconductive switch device of the present invention, and the breakdown voltage test was carried out under the same conditions. The test results are as follows: Figure 11 As shown. Figure 11As can be seen from the results, the asymmetric double-helix electrode structure of the present invention significantly improves the device's breakdown capability, reaching a breakdown voltage of 14-16 kV. This result further demonstrates the remarkable effectiveness of the present structure in optimizing electric field distribution, reducing local stress concentration, and improving device withstand voltage performance, demonstrating its significant engineering application value.

[0059] This embodiment achieves uniform expansion of current in radial and vertical directions through an asymmetric, counter-rotating double helix structure, and the two are arranged asymmetricly, thereby destroying the electric field symmetry and current channel concentration at the geometric level, and thus achieving device operating characteristics with uniform electric field, less heat accumulation, and strong current expansion. Specifically, the upper and lower electrodes rotate in opposite directions, causing the electric field vectors to interfere with and superimpose each other in multiple directions, forming an "interlaced" electric field interference distribution, which naturally breaks the central electric field superposition and edge field strength concentration phenomenon; the asymmetric pattern allows the current to extend a longer path in the plane and be "twisted and diffused" before entering the lower electrode, forming a larger power consumption area and smaller unit heat accumulation; the three-coupling optimization of current-electric field-thermal stress achieves the advantages of "reducing electric field peak → avoiding local current concentration → suppressing local temperature rise → improving breakdown voltage and device life".

[0060] It should be understood that the above embodiments are merely illustrative of the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent variations or modifications made in accordance with the spirit and substance of the present invention are intended to be encompassed within the scope of protection of the present invention.

Claims

1. A vertical optical switch, characterized in that: include: A substrate, an upper surface electrode disposed on the upper surface of the substrate, and a lower surface electrode disposed on the lower surface of the substrate; The projection of the upper surface electrode on the substrate does not completely overlap with the projection of the lower surface electrode on the substrate, and both the upper surface electrode and the lower surface electrode have an asymmetric structure; The electric field vector generated by the upper surface electrode and the electric field vector generated by the lower surface electrode interfere and overlap in different directions to form an interlaced electric field.

2. The vertical optical switch according to claim 1, wherein: The upper surface electrode and the lower surface electrode include: a spiral electrode, a curved staggered electrode and a radial grid electrode; and the upper surface electrode and the lower surface electrode are the same electrode.

3. The vertical optical switch according to claim 1, wherein: The upper surface electrode and the lower surface electrode are both spiral electrodes; The upper surface electrode and the lower surface electrode rotate in opposite directions, and the current flowing into the upper surface electrode has the same direction as the current flowing into the lower surface electrode.

4. The vertical optical switch according to claim 3, wherein: The projection of the upper surface electrode on the substrate and the projection of the lower surface electrode on the substrate are concentrically nested with each other.

5. The vertical optical switch according to claim 1, wherein: The upper surface electrode and the lower surface electrode are both spiral electrodes; The upper surface electrode and the lower surface electrode rotate in the same direction, and the projection of the upper surface electrode on the substrate is not concentric with the projection of the lower surface electrode on the substrate. The current passing through the upper surface electrode is in the opposite direction to the current passing through the lower surface electrode.

6. The vertical optical switch according to claim 5, wherein: The distance between the projection of the center of the upper surface electrode on the substrate and the projection of the center of the lower surface electrode on the substrate is 300-800 μm.

7. The vertical optical switch according to any one of claims 3 to 6, wherein: The electrode line width of the spiral electrode is 100-200 μm; And / or, the pitch of the spiral electrode is 400-800 μm.

8. The vertical optical switch according to any one of claims 3 to 6, wherein: The outer diameter of the spiral electrode is 5-8 mm; And / or, the inner diameter of the spiral electrode is 2.5-4 mm.

9. The vertical optical switch according to claim 1, wherein: The substrate is made of semi-insulating iron-doped gallium nitride single crystal material, and the vertical photoconductive switch comprises a vertical gallium nitride photoconductive switch.

10. A method for preparing a vertical photoconductive switch, for preparing the vertical photoconductive switch according to any one of claims 1 to 9, characterized in that: The preparation method comprises: providing a substrate; preparing an upper surface electrode on the upper surface of the substrate; preparing a lower surface electrode on the lower surface of the substrate; Among them, the projection of the upper surface electrode on the substrate does not completely overlap with the projection of the lower surface electrode on the substrate, and the upper surface electrode and the lower surface electrode are both asymmetric structures; the electric field vector generated by the upper surface electrode and the electric field vector generated by the lower surface electrode interfere and superimpose in different directions to form an interlaced electric field.

Images