A diamond photoconductive switch with high output power and its preparation method

Abstract

The present invention relates to a high-output power diamond photoconductive switch and a preparation method thereof, comprising: a diamond layer; a dielectric layer, the dielectric layer comprises a plurality of dielectric sublayers, all dielectric sublayers are arrayed on the diamond layer, and the spacing between two adjacent dielectric sublayers is greater than zero; a first ohmic contact electrode, the first ohmic contact electrode is located on the diamond layer not covered by the dielectric layer, and the upper surface of each dielectric sublayer is partially covered with the first ohmic contact electrode to form a field plate structure, wherein the first ohmic contact electrode covered on the dielectric sublayer and the first ohmic contact electrode disposed on the diamond layer at the same end of the dielectric sublayer are continuously arranged; a second ohmic contact electrode, the second ohmic contact electrode is located on the lower surface of the diamond layer. The photoconductive switch of the present invention can obtain a larger light receiving area, thereby reducing the on-resistance of the device and improving the output power of the diamond photoconductive switch.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and particularly relates to a diamond photoconductive switch with high output power and a preparation method thereof. Background Art

[0002] Pulse power technology is a technology that releases the energy of energy storage elements to a load through a high-speed switch in an extremely short time, thereby obtaining extremely high instantaneous output power. It can be applied to fields such as high-power pulse power supplies, DC induction accelerators, impulse radars, high-energy ignition devices, and electromagnetic drives. Traditional gas and semiconductor electronic control switches are restricted in further development in this field due to problems such as limited power capacity and switching speed, susceptibility to electromagnetic interference, severe random jitter, and low repetition frequency.

[0003] A photoconductive switch is a device that uses a pulsed laser light source to excite non-equilibrium carriers inside a semiconductor, thereby instantaneously changing the conductive characteristics of the semiconductor and realizing the control of the switch to close. Compared with traditional switches, it has the advantages of simple structure, fast conduction speed, immunity to electromagnetic interference, small jitter, and the ability to achieve high repetition frequency and high power output, making it a key device for developing the next generation of pulse power technology.

[0004] In order to enable the photoconductive switch to obtain a greater instantaneous output power, the breakdown voltage and conduction characteristics of the photoconductive switch are the key points in device research and development. According to the electric power formula, the instantaneous output power obtained on the load is determined by its conduction voltage and current. This means that the higher the off-state breakdown voltage of the photoconductive switch, the smaller the on-state conduction resistance, the larger the conduction current, and the faster the speed, the greater the power obtained by the load. Currently, photoconductive switches prepared from materials such as Si and GaAs are difficult to be competent in ultra-high power and high repetition frequency application fields due to low breakdown voltage, low carrier mobility, and phenomena such as persistent photoconductivity and thermal runaway. Although photoconductive switches prepared from SiC and GaN materials have good switching characteristics, they still have problems such as current filaments that affect the reliability of the switch, and their output power still does not meet the requirements of high power and high repetition frequency applications. With the continuous development of technology and the increasingly strong demand for higher-performance photoconductive switches, it has urged people to research and develop higher-performance photoconductive switches.

[0005] Diamond has an extremely high theoretical breakdown field strength (10 MV / cm), high carrier mobility (electron 4500 cm 2 / Vs, hole 3800 cm 2 / Vs) and saturation drift velocity (3×10 7cm / s), a relatively small dielectric constant (5.7), an extremely high thermal conductivity (2200 W / mK), and extremely strong survivability in harsh environments (strong radiation resistance and chemical inertness). This enables the photoconductive switch made of diamond to have a higher breakdown voltage and output current, and its response speed will also be faster. Its extremely high thermal conductivity also greatly alleviates the thermal failure problem of the device, having stronger performance advantages compared to the above materials. However, according to the current research results, the following problems still exist in improving the output power of diamond photoconductive switches:

[0006] On the one hand, the off-state breakdown voltage of diamond photoconductive switches is still much lower than its theoretical value. This is because the peak electric field of the device is mainly concentrated at the electrode edge, far greater than the internal electric field of the device, resulting in premature breakdown of the device at the electrode, thus reducing the switch peak voltage. Developing technologies to improve the breakdown voltage of the device remains a key factor.

[0007] On the other hand, how to reduce the on-resistance and increase the output current during conduction is another key factor. From the device working mechanism, the avalanche multiplication effect can be triggered by using a high operating voltage, the photosensitive area of the device can be enhanced to increase the number of photo-generated carriers, and the carrier transport characteristics can be improved to achieve the above goals. Currently, diamond electronic devices are usually fabricated using diamond plates, which are blocks with a length and width of several millimeters each and a thickness of micrometer level. Therefore, most current traditional device structures adopt interdigitated coplanar electrodes or opposite sandwich structure electrodes. For the traditional interdigitated coplanar electrode structure, the incident light enters from the front (as Figure 1 shown), and its electrodes are fabricated at the largest area of the material to obtain the largest light-receiving area and excite more non-equilibrium carriers. However, due to the small spacing between the interdigitated electrodes, the surface electric field strength is very high, making it difficult to obtain an absolute high breakdown voltage, and surface flashover is also likely to occur, easily causing device failure. If the electrode spacing is increased, the on-resistance is increased. Additionally, since the electric field lines are arc-shaped, it is not conducive to the transport of non-equilibrium carriers. For the traditional opposite sandwich structure electrode structure (as Figure 2 shown), since the incident light cannot penetrate the front metal electrode region, the side incident method is usually adopted, and the side area is small. Therefore, the light-receiving area of the device with this structure is small, the number of excited carriers is low, the on-resistance is high, and due to the limited incident depth of light, the utilization rate of the conduction region of the entire switch is limited, further restricting the output current.

[0008] The above problems limit the performance of current diamond photoconductive switches and hinder their further application in pulsed power technology. Summary of the Invention

[0009] To solve the above problems existing in the prior art, the present invention provides a diamond photoconductive switch with high output power and a preparation method thereof. The technical problems to be solved by the present invention are realized through the following technical solutions:

[0010] An embodiment of the present invention provides a diamond photoconductive switch with high output power, and the diamond photoconductive switch includes:

[0011] A diamond layer;

[0012] A dielectric layer, the dielectric layer includes a plurality of dielectric sub-layers, all the dielectric sub-layers are arranged in an array on the diamond layer, and the distance between two adjacent dielectric sub-layers is greater than zero;

[0013] A first ohmic contact electrode, the first ohmic contact electrode is located on the diamond layer not covered by the dielectric layer, and the upper surface of each dielectric sub-layer is partially covered with the first ohmic contact electrode to form a field plate structure, wherein the first ohmic contact electrode covering the dielectric sub-layer and the first ohmic contact electrode arranged on the diamond layer at the same end of this dielectric sub-layer are continuously arranged;

[0014] A second ohmic contact electrode, the second ohmic contact electrode is located on the lower surface of the diamond layer.

[0015] In an embodiment of the present invention, the diamond layer and the dielectric sub-layers are square, the dielectric sub-layers are respectively arranged at the four corners of the diamond layer, and the edge of the outermost dielectric sub-layer is flush with the edge of the diamond layer. The peripheral surfaces of the remaining dielectric sub-layers except those located at the four corners of the diamond layer are all covered with the first ohmic contact electrode, and the middle area of the dielectric sub-layer is exposed. The end surfaces of the two other ends of the dielectric sub-layers located at the four corners of the diamond layer except the ones flush with the edge of the diamond layer are all covered with the first ohmic contact electrode.

[0016] In an embodiment of the present invention, the ratio of the width d2 of the upper part electrode strip of the first ohmic contact electrode to the distance d3 between the upper part electrode strips of the two first ohmic contact electrodes is 1:4 to 1:5; the ratio of the width d1 of the lower part electrode strip of the first ohmic contact electrode to the width d2 of the upper part electrode strip of the first ohmic contact electrode is 1:4 to 1:5.

[0017] In an embodiment of the present invention, the band gap width of the dielectric layer is greater than that of the diamond layer.

[0018] In an embodiment of the present invention, the material of the dielectric layer includes SiO 2 Or Al 2 O 3 .

[0019] In one embodiment of the present invention, the thickness of the dielectric layer is 100 - 300 nm.

[0020] In one embodiment of the present invention, the diamond includes single-crystal diamond or polycrystalline diamond.

[0021] In one embodiment of the present invention, the structures of the first ohmic contact electrode and the second ohmic contact electrode include a multi-layer metal structure or a hydrogen termination / metal electrode regulation structure.

[0022] In one embodiment of the present invention, the multi-layer metal structure includes a Ti / Pt / Au multi-layer metal structure.

[0023] One embodiment of the present invention further provides a method for preparing a diamond photoconductive switch with high output power. The preparation method is used to prepare the diamond photoconductive switch described in any of the above embodiments, and the preparation method includes:

[0024] Step 1: Select a diamond layer and clean the surface of the diamond layer.

[0025] Step 2: Deposit a dielectric layer material on the upper surface of the diamond layer;

[0026] Step 3: Perform a first photolithography on the surface of the dielectric layer material to prepare a pattern of the ohmic contact electrode region, etch away the dielectric layer material in the ohmic contact electrode region pattern, expose the surface of the diamond layer, and form a dielectric layer including a plurality of dielectric sub-layers arranged in an array;

[0027] Step 4: Deposit an electrode material on the upper surface of the diamond layer, the upper surface of a part of the dielectric layer, and the lower surface of the diamond layer, and form a second ohmic contact electrode on the lower surface of the diamond layer;

[0028] Step 5: Perform photolithography on the electrode materials on the upper surface of the diamond layer and the upper surface of the dielectric layer, etch away the electrode materials in the light-transmitting region, and retain the electrode materials in contact with the diamond surface and the electrode materials above a part of the dielectric layer to form a first ohmic contact electrode, thus completing the preparation of the diamond photoconductive switch.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] The diamond photoconductive switch with a mesh electrode and a field plate structure provided by the present invention has a sandwich-structured device electrode. The upper surface electrode (i.e., the first ohmic contact electrode) is a mesh electrode with a field plate structure, which can obtain a larger light-receiving area, thereby reducing the on-resistance of the device and increasing the output current. At the same time, since the peak electric field at the electrode edge is reduced, the breakdown voltage of the device is increased and the off-state leakage of the device is reduced, ultimately improving the output power of the diamond photoconductive switch.

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0032] Figure 1 is a structural diagram of a common photoconductive switch provided by an embodiment of the present invention;

[0033] Figure 2 is a structural diagram of another common photoconductive switch provided by an embodiment of the present invention;

[0034] Figure 3 is a top view of the structure of a diamond photoconductive switch with high output power provided by an embodiment of the present invention;

[0035] Figure 4 is provided by an embodiment of the present invention Figure 3 schematic cross-sectional structure diagram of the diamond photoconductive switch along A-A;

[0036] Figure 5a - Figure 5f is a process flow chart of a preparation method of a diamond photoconductive switch with high output power provided by an embodiment of the present invention;

[0037] Figure 6 is an optimized effect diagram of the peak electric field along B-B of a diamond photoconductive switch with high output power provided by an embodiment of the present invention.

[0038] Symbol Explanation:

[0039] 1 - diamond layer, 2 - dielectric layer, 3 - first ohmic contact electrode, 4 - second ohmic contact electrode, 5 - photoresist. Detailed Embodiments

[0040] The present invention will be further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0041] It should be noted that the "upper", "lower", "left", and "right" mentioned in this embodiment refer to the positional relationship when the diamond photoconductive switch is in the illustrated state, the "width" refers to the horizontal dimension when the diamond photoconductive switch is in the illustrated state, and the "thickness" refers to the longitudinal dimension when the diamond photoconductive switch is in the illustrated state.

[0042] Please refer to Figure 3And Figure 4 , Figure 3 is a top view of the structure of a diamond photoconductive switch with high output power provided by an embodiment of the present invention, Figure 4 is provided by an embodiment of the present invention Figure 3 Schematic cross-sectional structure diagram of the diamond photoconductive switch along A-A. The present invention provides a diamond photoconductive switch with high output power. The diamond photoconductive switch includes:

[0043] Diamond layer 1;

[0044] Dielectric layer 2. The dielectric layer 2 includes a plurality of dielectric sub-layers. All the dielectric sub-layers are arranged in an array on the diamond layer 2, and the distance between two adjacent dielectric sub-layers is greater than zero;

[0045] First ohmic contact electrode 3. The first ohmic contact electrode 3 is located on the diamond layer 1 not covered by the dielectric layer 2, and the upper surface of each dielectric sub-layer is partially covered with the first ohmic contact electrode 3 to form a field plate structure. Among them, the first ohmic contact electrode 3 covering the dielectric sub-layer and the first ohmic contact electrode 3 arranged at the same end of the dielectric sub-layer on the diamond layer 1 are continuously arranged;

[0046] Second ohmic contact electrode 4. The second ohmic contact electrode 4 is located on the lower surface of the diamond layer 1.

[0047] Thus, the incident light is incident from above the mesh-shaped first ohmic contact electrode on the upper surface of the diamond photoconductive switch to trigger the on and off of the device.

[0048] Furthermore, the diamond layer 1 and the dielectric sub-layers are square, such as square or rectangular. Dielectric sub-layers are respectively arranged at the four corners of the diamond layer 1, and the edges of the outermost dielectric sub-layers are flush with the edges of the diamond layer 1. The peripheral surfaces of the remaining dielectric sub-layers except those located at the four corners of the diamond layer 1 are all covered with the first ohmic contact electrode 3, and the middle regions of the dielectric sub-layers are exposed. The end surfaces of the two other ends of the dielectric sub-layers located at the four corners of the diamond layer 1 except those flush with the edges of the diamond layer 1 are all covered with the first ohmic contact electrode 3, that is, there are also partially exposed areas of the dielectric sub-layers located at the four corners of the diamond layer 1 that are not covered by the first ohmic contact electrode 3. In addition, the diamond layer 1 and the dielectric sub-layers can also be circular, etc., and those skilled in the art can adjust according to the actual situation.

[0049] Therefore, the diamond photoconductive switch of the present invention is prepared by using a face-to-face sandwich structure. Among them, a dielectric layer 2 is inserted between the diamond layer 1 and the first ohmic contact electrode 3, and the first ohmic contact electrode 3 is a mesh electrode with a field plate structure. Thus, a larger light-receiving area can be obtained, thereby reducing the on-resistance of the device and increasing the output current. And the present invention forms a field plate structure by covering the first ohmic contact electrode 3 at the edge of the dielectric sub-layer. This structure can reduce the peak electric field at the electrode edge, thereby increasing the breakdown voltage of the device and enhancing the maximum voltage obtained by the load. In addition, the insulating dielectric field plate structure formed by introducing the dielectric layer 2 on the surface of the diamond photoconductive switch of the present invention can also prevent the movement of surface charges and the entry of external mobile charges, reduce the off-state leakage current of the device under high bias voltage, reduce the off-state power loss, and further suppress the air breakdown problem, improving the reliability of the device.

[0050] In the face-to-face sandwich electrode structure adopted by the present invention, ohmic contact electrodes are made on the two largest surfaces (upper and lower surfaces) of the diamond layer. Among them, the upper electrode (the first ohmic contact electrode 3) is the light-receiving surface, that is, the incident surface for triggering light, and the lower electrode (the second ohmic contact electrode 4) is connected to the bottom plate of the package housing. The upper electrode adopts a mesh electrode structure, and the field plate dielectric does not absorb the ultraviolet light that triggers the device to conduct. Therefore, the incident light energy can be maximally utilized, the light-receiving area can be increased, thereby exciting more non-equilibrium carriers, reducing the on-resistance, and enhancing the output current. Further, compared with the traditional coplanar interdigital electrode structure, the electric field lines of the present invention are linearly distributed from the upper electrode to the lower electrode. After the non-equilibrium carriers are generated on the surface of the upper electrode, the carrier transport is the shortest path, and the best transport effect can be obtained.

[0051] In a specific embodiment, in order to ensure that the light-receiving area can reach more than 80% of the upper surface area of the diamond and ensure sufficient light-receiving area, the ratio of the width d2 of the upper part electrode strip of the first ohmic contact electrode 3 to the distance d3 between the upper part electrode strips of the two first ohmic contact electrodes 3 is set to 1:4 to 1:5. In order to reduce the peak electric field at the electrode edge by more than one time and make the electric field evenly and continuously distributed inside the device, the ratio of the width d1 of the lower part electrode strip of the first ohmic contact electrode 3 to the width d2 of the upper part electrode strip of the first ohmic contact electrode 3 is set to 1:4 to 1:5. Among them, the lower part electrode strip of the first ohmic contact electrode 3 is the part located between the two dielectric sub-layers, and the upper part electrode strip of the first ohmic contact electrode 3 is the part located above the dielectric sub-layer.

[0052] In a specific embodiment, the band gap width of the dielectric layer 2 is greater than that of the diamond layer 1 to avoid the absorption of the triggering light by the dielectric layer 2.

[0053] Optionally, the material of the dielectric layer 2 includes SiO 2 Or Al2 O 3 。

[0054] Optionally, since a too thick dielectric layer thickness will increase the manufacturing costs of the dielectric layer and the electrode manufacturing process, and a too thin dielectric layer is not conducive to improving the surface breakdown voltage, when the thickness of the dielectric layer 2 is 100-300 nm, it can not only improve the surface breakdown voltage, but also will not excessively increase the manufacturing costs of the dielectric layer and the electrode manufacturing process.

[0055] In a specific embodiment, the structures of the first ohmic contact electrode 3 and the second ohmic contact electrode 4 include a multi-layer metal structure or a hydrogen termination / metal electrode regulation structure, which can form an ohmic contact with the diamond layer 1, thereby reducing the switch electrode contact impedance, facilitating the reduction of the switch on-state impedance, and improving the output power.

[0056] Optionally, the multi-layer metal structure includes a Ti / Pt / Au multi-layer metal structure, and Ti / Pt / Au is a stacked arrangement of Ti, Pt, and Au from bottom to top.

[0057] Optionally, the diamond includes single crystal diamond or polycrystalline diamond.

[0058] The diamond photoconductive switch with a mesh electrode and a field plate structure provided by the present invention has a sandwich structure for the device electrodes, wherein the upper surface electrode (i.e., the first ohmic contact electrode) is a mesh electrode with a field plate structure, which can obtain a larger light-receiving area, thereby reducing the device on-state resistance and increasing the output current; at the same time, since the peak electric field at the electrode edge is reduced, the device breakdown voltage is increased and the device off-state leakage current is reduced, ultimately improving the output power of the diamond photoconductive switch.

[0059] The diamond photoconductive switch structure provided by the present invention combines more non-equilibrium carriers generated by a large light-receiving area on the basis of improving the breakdown voltage, which can more effectively trigger the avalanche multiplication effect, further reduce the on-state resistance, increase the output current, and thus enhance the instantaneous output power of the device.

[0060] Embodiment 2

[0061] On the basis of Embodiment 1, the present invention further provides a manufacturing method for a diamond photoconductive switch with high output power. This manufacturing method is used to manufacture the diamond photoconductive switch with high output power described in Embodiment 1. Please refer to Figure 5a - Figure 5f , Figure 5a - Figure 5f is the process flow chart of a manufacturing method for a diamond photoconductive switch with high output power provided by an embodiment of the present invention. The manufacturing method for a diamond photoconductive switch with high output power provided by the present invention includes:

[0062] Step 1, as shown in Figure 5a , select the diamond layer 1 and clean the surface of the diamond layer 1.

[0063] Specifically, the diamond layer 1 is placed in an HNO 3 :H 2 SO 4 (1:1) solution for 20 minutes, and then successively placed in an acetone solution, absolute ethanol, and deionized water for ultrasonic cleaning for 15 minutes.

[0064] Step 2, as Figure 5b shown, deposit a dielectric layer material on the upper surface of the diamond layer.

[0065] Specifically, if Al 2 O 3 is used as the dielectric layer material, then radio frequency sputtering technology is adopted, and a mixed gas of O 2 and Ar is used to deposit a 200-nm-thick Al 2 O 3 layer on the upper surface of the diamond layer 1 as the dielectric layer under the conditions of a radio frequency power of 200 W and a gas pressure of 2 - 3 Pa.

[0066] If SiO 2 is used as the dielectric layer material, then SiH 4 and N 2 O are used as raw materials, and a 200-nm-thick SiO 2 dielectric layer is deposited on the upper surface of the diamond layer 1 by PECVD method.

[0067] Step 3, as Figure 5c shown, perform a photolithography on the surface of the dielectric layer material to prepare a pattern of the ohmic contact electrode region, etch away the dielectric layer material in the ohmic contact electrode region pattern, expose the surface of the diamond layer, and form a dielectric layer 2 including a plurality of dielectric sub-layers arranged in an array.

[0068] Specifically, spin-coat a photoresist on the surface of the dielectric layer, use a photomask with a pattern of a mesh-shaped ohmic contact region as a mask, expose it with a lithography machine, and remove the photoresist above this region to expose the surface of the dielectric layer.

[0069] If the dielectric layer uses Al 2 O 3 material, then etch for 3 minutes under the conditions of a radio frequency power of 200 W, a working gas of BCl 3 , a gas flow rate of 30 sccm, and a gas pressure of 1 Pa to remove the Al 2 O 3 dielectric layer material in the ohmic contact region, expose the surface of the diamond layer in this region, and remove the photoresist.

[0070] If the insulating dielectric layer uses SiO 2For the material, under the conditions of a radio frequency power of 400 W, a working gas of CHF 3 , a gas flow rate of 20 sccm, and a pressure of 5 Pa, etch for 3 min to remove the SiO 2 dielectric layer material in the ohmic contact region, expose the surface of the diamond layer in this region, and remove the photoresist.

[0071] Step 4: As shown in Figure 5d , deposit electrode material on the upper surface of the diamond layer, the upper surface of part of the dielectric layer 2, and the lower surface of the diamond layer, and form a second ohmic contact electrode 4 on the lower surface of the diamond layer.

[0072] Specifically, deposit electrode layers on the upper and lower surfaces of the diamond photoconductive switch and form ohmic contacts with the diamond layer 1.

[0073] If the ohmic contact electrode adopts a multi-layer metal structure, use electron beam evaporation technology to deposit Ti / Pt / Au multi-layer metals on the upper and lower surfaces of the diamond layer 1 in sequence, with thicknesses of 50 / 150 / 50 nm respectively. Perform heat treatment in a nitrogen atmosphere, with the heat treatment temperature being 750 - 850 °C and the heat treatment time being 20 - 30 seconds to form the ohmic contact electrode.

[0074] If the ohmic contact electrode adopts a hydrogen termination / metal electrode regulation structure, place the device in a microwave plasma chemical vapor deposition (MPCVD) system, and under the conditions of a hydrogen flow rate of 500 - 700 sccm, a temperature of 600 - 900 °C, a pressure of 100 - 200 mbar, a methane concentration of 0.1%, and a microwave power of 1 - 2 kW, treat for 10 - 15 min to form a hydrogen-terminated diamond surface. Then use electron beam evaporation to deposit a 250 nm thick Au layer on the upper and lower surfaces of the diamond to form an ohmic contact.

[0075] Step 5: Perform photolithography on the electrode materials on the upper surface of the diamond layer and the upper surface of the dielectric layer 2, etch away the electrode materials in the light-transmitting region, and retain the electrode materials in contact with the diamond surface and part of the electrode materials above the dielectric layer 2 to form a first ohmic contact electrode 3, thus completing the preparation of the diamond photoconductive switch.

[0076] Specifically, as shown in Figure 5eAs shown in the figure, a photoresist 5 is spin-coated on the surface of the first ohmic contact electrode 3. Using a photomask with a light-transmitting area pattern as a mask, it is exposed using a photolithography machine, and the photoresist above this area is removed. The exposed metal is etched, and the electrodes in the contact area with the diamond layer surface and the field plate area above the dielectric layer are retained. The cross-section of the first ohmic contact electrode 3 has a T-shaped structure, and when viewed from the front, it has a mesh structure. Then, the device is placed in a reactive ion etching (RIE) equipment and processed for 10 minutes in an environment where the oxygen flow rate, pressure, and power are 80 sccm, 8 Pa, and 150 W respectively. Then, the sidewalls of the device are insulated, as Figure 5f shown. Finally, the photoresist is removed, and the device fabrication is completed.

[0077] To illustrate the diamond photoconductive switch prepared by the present invention, please refer to Figure 6 , Figure 6 which shows the optimization effect of the surface peak electric field of the device using the structure of the present invention under the same applied bias voltage condition. Among them, for each electrode strip of the mesh electrode, the width of the lower part of the first ohmic contact electrode is 0.05 mm, the width of the upper part of the first ohmic contact electrode is 0.25 mm, and the distance between the upper part electrode strips of the two first ohmic contact electrodes is 1 mm. It can be seen that the highest surface peak electric field of the traditional field plate structure without a dielectric layer can reach 6 MV / cm, while the structure proposed by the present invention can reduce the peak electric field at the surface electrode edge to 3 MV / cm (SiO 2 dielectric) and 1.5 MV / cm (Al 2 O 3 dielectric) or less, which can effectively increase the breakdown voltage of the device and improve the output power of the device.

[0078] Due to the small breakdown voltage and light-receiving area, it is difficult for the traditional photoconductive switch structure to obtain a large output power. The photoconductive switch of the present invention adopts a mesh electrode with a field plate structure on the device surface, which can obtain a large light-receiving area, thereby reducing the on-resistance of the device and increasing the output current. At the same time, the implementation of the present invention significantly reduces the peak electric field at the edge of the device electrode, thereby increasing the breakdown voltage of the device and ultimately increasing the output power of the diamond photoconductive switch.

[0079] In the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0080] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0081] Although the present invention has been described herein in connection with various embodiments, however, in the process of implementing the claimed invention, those skilled in the art can understand and achieve other variations of the disclosed embodiments by viewing the accompanying drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "one" does not exclude a plurality. A single processor or other unit can implement several functions recited in the claims. Certain measures are recited in mutually different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

[0082] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, any modifications made without departing from the concept of the present invention should be regarded as falling within the protection scope of the present invention.

Claims

1. A diamond photoconductive switch with high output power, Characterized in that, The diamond photoconductive switch includes: A diamond layer (1); A dielectric layer (2), the dielectric layer (2) includes a plurality of dielectric sub-layers, all the dielectric sub-layers are arranged in an array on the diamond layer (1), and the distance between adjacent two dielectric sub-layers is greater than zero; A first ohmic contact electrode (3), the first ohmic contact electrode (3) is located on the diamond layer (1) not covered by the dielectric layer (2), and the upper surface of each dielectric sub-layer is partially covered with the first ohmic contact electrode (3) to form a field plate structure, wherein the first ohmic contact electrode (3) covering the dielectric sub-layer and the first ohmic contact electrode (3) arranged at the same end of the diamond layer (1) of this dielectric sub-layer are continuously arranged; A second ohmic contact electrode (4), the second ohmic contact electrode (4) is located on the lower surface of the diamond layer (1).

2. The diamond photoconductive switch with high output power according to claim 1, Characterized in that, The diamond layer (1) and the dielectric sub-layer are square, the dielectric sub-layers are respectively arranged at the four corners of the diamond layer (1), and the edge of the outermost dielectric sub-layer is flush with the edge of the diamond layer (1), and the peripheral surfaces of the remaining dielectric sub-layers except those located at the four corners of the diamond layer (1) are all covered with the first ohmic contact electrode (3) and the middle area of the dielectric sub-layer is exposed, and the end surfaces of the other two ends of the dielectric sub-layers located at the four corners of the diamond layer (1) except those flush with the edge of the diamond layer (1) are all covered with the first ohmic contact electrode (3).

3. The diamond photoconductive switch with high output power according to claim 2, Characterized in that, The ratio of the width d2 of the upper part electrode strip of the first ohmic contact electrode (3) to the distance d3 between the upper part electrode strips of the two first ohmic contact electrodes (3) is 1:4 to 1:5; the ratio of the width d1 of the lower part electrode strip of the first ohmic contact electrode (3) to the width d2 of the upper part electrode strip of the first ohmic contact electrode (3) is 1:4 to 1:

5.

4. The diamond photoconductive switch with high output power according to claim 1, Characterized in that, The band gap width of the dielectric layer (2) is greater than that of the diamond layer (1).

5. The diamond photoconductive switch with high output power according to claim 4, Characterized in that, The material of the dielectric layer (2) includes SiO 2 or Al 2 O 3 .

6. The diamond photoconductive switch with high output power according to claim 1, Characterized in that, The thickness of the dielectric layer (2) is 100 - 300 nm.

7. The diamond photoconductive switch with high output power according to claim 1, Characterized in that, The diamond includes single crystal diamond or polycrystalline diamond.

8. The diamond photoconductive switch with high output power according to claim 1, Characterized in that, The structures of the first ohmic contact electrode (3) and the second ohmic contact electrode (4) include a multi-layer metal structure or a hydrogen termination / metal electrode regulation structure.

9. The diamond photoconductive switch with high output power according to claim 8, characterized in that, the multi-layer metal structure includes a Ti / Pt / Au multi-layer metal structure.

10. A method for preparing a diamond photoconductive switch with high output power, characterized in that, the preparation method is used to prepare the diamond photoconductive switch according to any one of claims 1 to 9, and the preparation method includes: Step 1: Select the diamond layer (1) and clean the surface of the diamond layer (1); Step 2: Deposit a dielectric layer material on the upper surface of the diamond layer (1); Step 3: Perform a first photolithography on the surface of the dielectric layer material to prepare a pattern of the ohmic contact electrode region, etch away the dielectric layer material in the ohmic contact electrode region pattern, expose the surface of the diamond layer, and form a dielectric layer (2) including a plurality of dielectric sub-layers arranged in an array; Step 4: Deposit an electrode material on the upper surface of the diamond layer (1), the upper surface of a part of the dielectric layer (2), and the lower surface of the diamond layer, and form a second ohmic contact electrode (4) on the lower surface of the diamond layer (1); Step 5: Perform photolithography on the electrode materials on the upper surface of the diamond layer and the upper surface of the dielectric layer (2), etch away the electrode materials in the light-transmitting region, and retain the electrode materials in contact with the diamond surface and the electrode materials above a part of the dielectric layer (2) to form a first ohmic contact electrode (3), thus completing the preparation of the diamond photoconductive switch.

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