A longitudinal photoconductive switch with electrode spreading structure and method of making the same

Abstract

The application provides a longitudinal light guide switch with an electrode expansion structure and a preparation method thereof, and relates to the technical field of semiconductor devices. The longitudinal light guide switch comprises a metal electrode formed on the side surface of the substrate layer at both ends; an aluminum-doped zinc oxide layer formed at the anode position of the substrate layer and symmetrically distributed on part of the light entrance surface and part of the back surface of the substrate layer; and a silicon nitride layer formed at the anode position and the cathode position of the substrate layer and symmetrically distributed on part of the light entrance surface and part of the back surface of the substrate layer, wherein the silicon nitride layer at the anode position is also symmetrically distributed on the aluminum-doped zinc oxide layer. In this way, the aluminum-doped zinc oxide layer and the silicon nitride layer are arranged on the metal electrode and the substrate layer, so that the light guide switch absorption efficiency is improved. Meanwhile, the aluminum-doped zinc oxide is used as the expansion structure, the current density of the metal electrode is dispersed, the silicon nitride layer is used as a passivation layer, the surface flashover between the metal electrodes is inhibited, and the switch withstand voltage capacity is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor devices, and in particular to a longitudinal photoconductive switch with an electrode expansion structure and a preparation method thereof. BACKGROUND

[0002] Pulse power technology is a technology that compresses energy in time and space to obtain high energy density output. With the development of high repetition rate pulse power and semiconductor technology, power semiconductor devices gradually replace or replace traditional switching devices. Compared with other power switches, photoconductive switches have the advantages of fast switching speed, optical isolation, compactness and high breakdown field strength. The photoconductive switch is composed of an ultrafast pulsed laser and a photoelectric semiconductor. Its principle is to use a specific wavelength of laser to control the "on" and "off" of the device, thereby realizing the output of pulses. As the third generation semiconductor material, silicon carbide has the characteristics of wide band gap, high breakdown field strength, high thermal conductivity, large saturated electron velocity, large hardness and chemical corrosion resistance, making silicon carbide suitable as a substrate for photoconductive switches.

[0003] At present, the structure of the photoconductive switch mainly has a lateral photoconductive switch and a longitudinal photoconductive switch. For the lateral photoconductive switch, although the electrode gap, incident light energy and area can be controlled, the electric field is easily concentrated on the side close to the middle of the cathode and the anode, reducing the voltage withstand capability of the switch. For the vertical photoconductive switch, it has a good electric field homogenization capability, but its voltage withstand is limited by the thickness of the substrate, and the single switch is limited in high voltage and high power applications. SUMMARY

[0004] The purpose of the embodiments of the present application is to provide a longitudinal photoconductive switch with an electrode expansion structure and a preparation method thereof, which solves the problem that the voltage withstand of the photoconductive switch in the prior art is limited by the thickness of the substrate, and the single switch is limited in high voltage and high power applications.

[0005] To solve the above technical problems, the embodiments of the present application provide the following technical solutions:

[0006] The first aspect of the present application provides a longitudinal photoconductive switch with an electrode expansion structure, comprising a substrate layer, a metal electrode, an aluminum-doped zinc oxide layer and a silicon nitride layer.

[0007] The metal electrode is formed on the side surface of the two ends of the substrate layer.

[0008] The aluminum-doped zinc oxide layer is formed at the anode position of the substrate layer and is symmetrically distributed on part of the light entrance surface and part of the back surface of the substrate layer. The anode position is a position on one side of the substrate layer.

[0009] The silicon nitride layer is formed at the anode position and the cathode position of the substrate layer and symmetrically distributed on the partial light entrance surface and the partial back surface of the substrate layer. The silicon nitride layer at the anode position is also symmetrically distributed on the aluminum-doped zinc oxide layer. The cathode position is the position on the other side of the substrate layer.

[0010] In some modified embodiments of the first aspect of the present application, the metal electrode comprises a first metal electrode, a second metal electrode and a third metal electrode, which are sequentially stacked on the side surface of the two ends of the substrate layer.

[0011] In some modified embodiments of the first aspect of the present application, the material of the first metal electrode is a nickel material, the thickness of the first metal electrode ranges from 180 nm to 220 nm, the material of the second metal electrode is a titanium material, the thickness of the second metal electrode ranges from 100 nm to 140 nm, and the material of the third metal electrode is a gold material, the thickness of the third metal electrode ranges from 50 nm to 150 nm.

[0012] In some modified embodiments of the first aspect of the present application, the metal electrode, the aluminum-doped zinc oxide layer and the silicon nitride layer at the cathode position all have a rectangular shape.

[0013] In some modified embodiments of the first aspect of the present application, the material of the substrate layer comprises a silicon carbide material, the resistivity of the substrate layer is greater than 10 9 Ω cm, and the thickness of the substrate layer ranges from 1 mm to 2 mm.

[0014] In some modified embodiments of the first aspect of the present application, the edge corner of the aluminum-doped zinc oxide layer is a 90° circular arc.

[0015] In some modified embodiments of the first aspect of the present application, the doping concentration of the aluminum-doped zinc oxide layer ranges from 1x10 14 -1x10 17 cm -3 , the resistivity of the aluminum-doped zinc oxide layer ranges from 10 Ω cm to 100 Ω cm, and the thickness of the aluminum-doped zinc oxide layer ranges from 100 nm to 200 nm.

[0016] In some modified embodiments of the first aspect of the present application, the resistivity of the silicon nitride layer is greater than 10 6 Ω cm, and the thickness of the silicon nitride layer ranges from 100 nm to 200 nm.

[0017] The second aspect of the present application provides a preparation method of a longitudinal type light guide switch with an electrode expansion structure, comprising:

[0018] The substrate layer is cleaned by using the RCA standard cleaning method, and the material of the substrate layer is a silicon carbide material.

[0019] The first metal electrode is prepared on the side surface of the substrate layer at the electrode area of the substrate layer by using a magnetron sputtering method or an electron beam evaporation method, and the material of the first metal electrode is a nickel material;

[0020] The first metal electrode and the substrate layer are formed into a nickel-silicon alloy by using an RTP rapid annealing method;

[0021] The second metal electrode and the third metal electrode are sequentially grown on the first metal electrode after the rapid annealing on both sides by using a magnetron sputtering method or an electron beam evaporation method, the material of the second metal electrode is a titanium material, and the material of the third metal electrode is a gold material;

[0022] The placing direction of the current device after the growth of the third metal electrode is adjusted to be perpendicular to the placing direction of the substrate layer, and the zinc oxide layer doped with aluminum is grown on the surface of the substrate layer at the both sides of the anode position by using a magnetron sputtering method or an electron beam evaporation method, the anode position being the position of one side of the substrate layer;

[0023] The silicon nitride layer is grown on the surface of the substrate layer at the both sides of the anode position, the both sides of the zinc oxide layer doped with aluminum and the both sides of the cathode position of the substrate layer by using a magnetron sputtering method or an electron beam evaporation method, the cathode position being the position of the other side of the substrate layer;

[0024] The nano-silver paste is coated on the third metal electrode and connected with a copper strip, high-temperature sintering is performed under a preset temperature condition, the silver contact is formed by the third metal electrode, the nano-silver paste and the copper strip, the device after the silver contact is encapsulated by using an epoxy resin, and the preparation of the longitudinal light guide switch with the electrode expansion structure is completed.

[0025] In some modified embodiments of the second aspect of the application, the doping concentration of the zinc oxide layer doped with aluminum ranges from 1x10 14 -1x10 17 cm -3 , the resistivity of the zinc oxide layer doped with aluminum ranges from 10Ω cm-100Ω cm, the thickness ranges from 100-200nm, the resistivity of the silicon nitride layer is >10 6 Ω cm, and the thickness ranges from 100-200nm.

[0026] Compared with the prior art, the longitudinal light guide switch with electrode expansion structure and the preparation method thereof provided by the application have the advantages that the longitudinal light guide switch with electrode expansion structure comprises a substrate layer, a metal electrode, an aluminum-doped zinc oxide layer and a silicon nitride layer; the metal electrode is formed on the side surface of the two ends of the substrate layer; the aluminum-doped zinc oxide layer is formed at the anode position of the substrate layer and symmetrically distributed on part of the light entrance surface and part of the back surface of the substrate layer; the silicon nitride layer is formed at the anode position and the cathode position of the substrate layer and symmetrically distributed on part of the light entrance surface and part of the back surface of the substrate layer; the silicon nitride layer at the anode position is also symmetrically distributed on the aluminum-doped zinc oxide layer; and the cathode position is the position on the other side of the substrate layer. In this way, by arranging the aluminum-doped zinc oxide layer and the silicon nitride layer on the metal electrode and the substrate layer, the electrode edge electric field is dispersed, the risk of switch breakdown is reduced, the longitudinal light guide switch with electrode expansion structure can absorb more photons to generate photo-generated carriers, and the light guide switch absorption efficiency is improved; at the same time, the aluminum-doped zinc oxide is used as the expansion structure to disperse the current density of the metal electrode, the silicon nitride layer is used as the passivation layer to inhibit the surface flashover between the metal electrodes, and the switch withstand voltage capacity is improved. BRIEF DESCRIPTION OF DRAWINGS

[0027] The above and other objects, features and advantages of the exemplary embodiments of the present application will be more apparent from the following detailed description read in conjunction with the accompanying drawings, in which several embodiments of the present application are shown by way of example, and wherein the same reference numerals refer to the same or similar components throughout the several views, in which:

[0028] Figure 1 A structure schematic diagram of the longitudinal light guide switch with electrode expansion structure is schematically shown;

[0029] Figure 2 A flow chart of the preparation method of the longitudinal light guide switch with electrode expansion structure is schematically shown;

[0030] Figure 3 A preparation process schematic diagram of the longitudinal light guide switch with electrode expansion structure is schematically shown;

[0031] Figure 4 An electric field intensity distribution diagram of the longitudinal light guide switch with electrode expansion structure under light irradiation is schematically shown;

[0032] Figure 5 An electric field intensity distribution diagram of the transverse heterogeneous light guide switch under light irradiation is schematically shown;

[0033] Figure 6 A comparison diagram of the measured output signals of the longitudinal light guide switch with electrode expansion structure and the transverse heterogeneous light guide switch under the same conditions is schematically shown.

[0034] Reference Signs List

[0035] 1, substrate layer; 2, metal electrode; 21, first metal electrode; 22, second metal electrode; 23, third metal electrode; 3, aluminum-doped zinc oxide layer; 4, silicon nitride layer. DETAILED DESCRIPTION

[0036] Exemplary embodiments of the present application will be described in detail with reference to the drawings. Although exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application can be embodied in various forms without being limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present application to those skilled in the art.

[0037] It should be noted that unless otherwise specified, technical terms or scientific terms used in the present application should be understood as having the same meaning as commonly understood by one of ordinary skill in the art to which the present application pertains.

[0038] The method in the embodiments of the present application will be described in detail below.

[0039] Figure 1 A structure diagram of a longitudinal light guide switch with electrode extension structure is schematically shown, which includes a substrate layer 1, a metal electrode 2, an aluminum-doped zinc oxide layer 3, and a silicon nitride layer 4.

[0040] The metal electrode 2 is formed on the side surfaces of the substrate layer 1 at both ends;

[0041] The aluminum-doped zinc oxide layer 3 is formed at the anode position of the substrate layer 1 and symmetrically distributed on the partial light-incident surface and the partial back surface of the substrate layer 1, and the anode position is the position on one side of the substrate layer 1.

[0042] The silicon nitride layer 4 is formed at the anode position and the cathode position of the substrate layer 1 and symmetrically distributed on the partial light-incident surface and the partial back surface of the substrate layer 1, and the silicon nitride layer 4 at the anode position is also symmetrically distributed on the aluminum-doped zinc oxide layer 3, and the cathode position is the position on the other side of the substrate layer 1.

[0043] Specifically, the aluminum-doped zinc oxide layer 3 and the silicon nitride layer 4 can be referred to as a field plate structure, wherein the field plate structure is located on the upper and lower side surfaces of the metal electrode 2 and on the partial upper and lower surfaces of the substrate layer 1.

[0044] The anode position and the cathode position are located at two opposite positions of the substrate layer 1. The substrate layer 1 is horizontally placed along the longest side of the substrate layer 1, wherein the light-in surface is the upper surface of the substrate layer 1 and the light-out surface is the lower surface of the substrate layer 1. The silicon nitride layer 4 in the anode position completely covers the aluminum-doped zinc oxide layer 3. The metal electrode 2 is symmetrically distributed on the side surfaces at both ends of the substrate layer 1, and the side receiving the laser, i.e., the light-in surface, is located in the middle region between the metal electrodes 2 at both ends.

[0045] The silicon nitride layer 4 is distributed on both sides of the metal electrode 2, which not only can serve as a passivation layer to prevent flashover of the switch surface, but also can play a role in increasing the transmittance and reducing the reflectance, thereby improving the current-carrying capacity of the photoconductive switch.

[0046] As an optional embodiment of the present application, the metal electrode 2 comprises a first metal electrode 21, a second metal electrode 22 and a third metal electrode 23, which are sequentially stacked on the side surfaces at both ends of the substrate layer 1.

[0047] As an optional embodiment of the present application, the material of the first metal electrode 21 is a nickel material, the thickness of the first metal electrode 21 ranges from 180 nm to 220 nm, the material of the second metal electrode 22 is a titanium material, the thickness of the second metal electrode 22 ranges from 100 nm to 140 nm, and the material of the third metal electrode 23 is a gold material, the thickness of the third metal electrode 23 ranges from 50 nm to 150 nm.

[0048] Specifically, the thickness of the first metal electrode 21 is preferably 200 nm, the thickness of the second metal electrode 22 is preferably 120 nm, and the thickness of the third metal electrode 23 is preferably 100 nm. The preferred thicknesses of the first metal electrode 21, the second metal electrode 22 and the third metal electrode 23 make the on-resistance lower.

[0049] As an optional embodiment of the present application, the shapes of the metal electrode 2, the aluminum-doped zinc oxide layer 3 and the silicon nitride layer 4 in the cathode position are all rectangular shapes.

[0050] As an optional embodiment of the present application, the material of the substrate layer 1 comprises a silicon carbide material, the resistivity of the substrate layer 1 is > 10 9 Ω cm, and the thickness of the substrate layer 1 ranges from 1 mm to 2 mm.

[0051] As an optional embodiment of the present application, the edge corner of the aluminum-doped zinc oxide layer 3 is a 90° circular arc.

[0052] As an optional embodiment of the present application, the doping concentration of the aluminum-doped zinc oxide layer 3 ranges from 1x10 14 -1x10 17 cm-3 The resistivity of the aluminum-doped zinc oxide layer 3 is in the range of 10Ω cm-100Ω cm, and the thickness is in the range of 100-200 nm.

[0053] Specifically, the resistivity of the aluminum-doped zinc oxide layer 3 is between the resistivity of the metal electrode 2 and the substrate layer 1, which can play the role of a buffer layer, reducing the influence of the electric field concentrated on the edge of the electrode; at the same time, the aluminum-doped zinc oxide layer 3 as a transparent conductive film can realize the effect of antireflection and transmittance for the incident laser, improving the output capacity of the photoconductive switch.

[0054] As an optional embodiment of the present application, the resistivity of the silicon nitride layer 4 is >10 6 Ω cm, and the thickness is in the range of 100-200 nm.

[0055] The present application uses the silicon nitride layer 4 as a passivation layer to inhibit the surface flashover between the metal electrodes 2, improving the withstand voltage capacity of the switch, and at the same time, uses the silicon nitride layer 4 as an electric field buffer zone to weaken the electric field on the edge of the electrode step by step, realizing the improvement of the withstand voltage performance and the improvement of the life characteristics of the photoconductive switch. In addition, the structure relative to the metal electrode 2 is set to further homogenize the switch electric field distribution, so that the electric field lines pass through the inside of the switch as much as possible, improving the reliability of the switch.

[0056] Based on the above Figure 1 The longitudinal photoconductive switch with electrode extension structure in the embodiment of the present application can absorb more photons to generate photo-generated carriers, improving the absorption efficiency of the photoconductive switch; at the same time, the aluminum-doped zinc oxide is used as an extension structure to disperse the current density of the metal electrode 2, and the silicon nitride layer 4 is used as a passivation layer to inhibit the surface flashover between the metal electrodes 2, improving the withstand voltage capacity of the switch.

[0057] Figure 2 The preparation method of the longitudinal photoconductive switch with electrode extension structure in the embodiment of the present application is schematically shown, which is described in detail as follows.Figure 2 The preparation method of the longitudinal type photoconductive switch with electrode extension structure is shown in the figure, which can include:

[0058] S201, using RCA standard cleaning method to clean the substrate layer 1.

[0059] The material of the substrate layer 1 is silicon carbide material.

[0060] Specifically, by wet chemical cleaning method (Radio Corporation of America, RCA) standard cleaning method, or acetone, ethanol, deionized water is respectively ultrasonic oscillation 5mm, and then high-purity nitrogen is blown dry to obtain clean silicon carbide.

[0061] Before using RCA standard cleaning method to clean the substrate layer 1, it includes: through diamond knife slicing or laser cutting, regular cuboid silicon carbide is obtained. The thickness of silicon carbide is 1-2mm, and the resistivity is greater than >10 9 Ω cm.

[0062] S202, using magnetron sputtering method or electron beam evaporation method, the first metal electrode 21 is prepared on the side surface of the substrate layer 1 at both ends of the electrode area of the substrate layer 1.

[0063] The material of the first metal electrode 21 is nickel material.

[0064] Specifically, Figure 3 The preparation process schematic diagram of the longitudinal type photoconductive switch with electrode extension structure is shown schematically, wherein, Figure 3 (a) is a schematic diagram of preparing the first metal electrode 21 on the side surface of one end of the substrate layer 1 in the electrode area of the substrate layer 1, Figure 3 (b) is a schematic diagram of preparing the first metal electrode 21 on the side surface of the other end of the substrate layer 1 in the electrode area of the substrate layer 1, and the first metal electrode 21 is prepared on the side surface of both ends of the substrate layer 1 in the electrode area of the substrate layer 1 by using magnetron sputtering method or electron beam evaporation method, which specifically includes: shielding by metal mask or photoresist, and preparing the first metal electrode 21 on the side surface of one end of the substrate layer 1 in the electrode area of the substrate layer 1 by using magnetron sputtering method or electron beam evaporation method, then turning over the two ends of the substrate layer 1, placing the side surface of one end of the substrate layer 1 on the side surface of the other end of the substrate layer 1, and preparing the first metal electrode 21 on the side surface of the other end of the substrate layer 1 in the electrode area of the substrate layer 1 in the same way as preparing the first metal electrode 21 on the side surface of one end of the substrate layer 1, to realize double-sided preparation of the first metal electrode 21.

[0065] Specifically, the substrate layer 1 is vertically placed on the metal mask, with one end of the substrate layer 1 facing upwards, and then placed in the magnetic control sputtering device. First, the magnetic control sputtering device is pumped to a low vacuum state, about 10E-1 Torr, and then the molecular pump is opened to pump the magnetic control sputtering device to a high vacuum state, about 5E-6 Torr. The sputtering power is controlled to be 100 W, and the first metal electrode 21, i.e. metal nickel, is obtained with a thickness of 180-220 nm. The magnetic control sputtering device is opened, the device prepared with metal nickel is flipped, and metal nickel is sputtered on the other end of the substrate layer 1 by the same sputtering method.

[0066] S203, by the RTP rapid annealing method, the first metal electrode 21 and the substrate layer 1 form a nickel-silicon alloy.

[0067] Specifically, under the conditions of low vacuum or inert gas protection and rapid high-temperature annealing, the metal nickel and silicon carbide form a nickel-silicon alloy by the rapid thermal processing (RTP) rapid annealing method to obtain a good ohmic contact.

[0068] The device prepared after the first metal electrode 21 is placed on the annealing table. First, the magnetic control sputtering device is pumped to a low vacuum state, and the gas in the cavity is maintained as an inert gas such as nitrogen by air exchange. Then, at 1000°C, it is maintained for 300 s to obtain a nickel-silicon alloy, and the contact resistivity is about 10 -4 Ω cm-10 -5 Ω cm.

[0069] S204, by the magnetic control sputtering method or the electron beam evaporation method, the second metal electrode 22 and the third metal electrode 23 are sequentially grown on the first metal electrode 21 after rapid annealing on both sides.

[0070] Among them, the material of the second metal electrode 22 is titanium material, and the material of the third metal electrode 23 is gold material.

[0071] Specifically, Figure 3 The preparation process of the longitudinal type light guide switch with electrode expansion structure is schematically shown, wherein, Figure 3 (c) is a schematic diagram of sequentially growing the second metal electrode 22 and the third metal electrode 23 on the first metal electrode 21 after rapid annealing on one side, Figure 3(d) is a schematic diagram of growing second metal electrode 22 and third metal electrode 23 on the first metal electrode 21 after rapid annealing on the other side, growing second metal electrode 22 and third metal electrode 23 on the first metal electrode 21 after rapid annealing on one side by using metal mask or photoresist shielding, magnetron sputtering method or electron beam evaporation method; then flip the one side of the device after growing third metal electrode 23, and place the one side of the device after growing third metal electrode 23 on the other side of the device which has not grown third metal electrode 23; grow second metal electrode 22 and third metal electrode 23 on the first metal electrode 21 after rapid annealing on the other side in the same way as growing second metal electrode 22 and third metal electrode 23 on the first metal electrode 21 after rapid annealing on one side, to realize growing second metal electrode 22 and third metal electrode 23 on both sides.

[0072] During the rapid annealing of the first metal electrode 21, place it vertically on the metal mask, and then place it in the magnetron sputtering revolution disc. First, extract the magnetron sputtering device to a low vacuum state, about 10E-1 Torr, then open the molecular pump, and extract the magnetron sputtering device to a high vacuum state, about 5E-6 Torr. Control the sputtering power to be 60W, and obtain 100-140nm second metal electrode 22, i.e. metal titanium. Then, on the basis of metal titanium, control the sputtering power to be 20W, and obtain 50-150nm second metal electrode 22, i.e. metal gold. Open the magnetron sputtering device, flip the device, and sputter metal titanium and metal gold on the other side according to the same sputtering method.

[0073] S205, adjust the placement direction of the current device after growing the third metal electrode 23, so that the placement direction of the current device is perpendicular to the placement direction of the substrate layer 1, and grow the aluminum-doped zinc oxide layer 3 on the surface of the two side parts of the substrate layer 1 in the anode position of the substrate layer 1 by using the magnetron sputtering method or the electron beam evaporation method.

[0074] Wherein, the anode position is the position on one side of the substrate layer 1, the doping concentration of the aluminum-doped zinc oxide layer 3 ranges from 1x10 14 -1x10 17 cm -3 , the resistivity of the aluminum-doped zinc oxide layer 3 ranges from 10Ω cm-100Ω cm, and the thickness ranges from 100-200nm.

[0075] Specifically, Figure 3 The preparation process of the longitudinal type photoconductive switch with electrode expansion structure is schematically shown, wherein, Figure 3 (e) is a schematic diagram of growing aluminum-doped zinc oxide layer 3 on the surface of the upper metal electrode, Figure 3(f) is a schematic view of growing the aluminum-doped zinc oxide layer 3 on the surface of the lower metal electrode, adjusting the placement direction of the current device after growing the third metal electrode 23, so that the placement direction of the current device is perpendicular to the placement direction of the substrate layer 1, and shielding by a metal mask or photoresist, growing the aluminum-doped zinc oxide layer 3 on the surface of the upper part of the substrate layer 1 in the anode position of the substrate layer 1 by a magnetron sputtering method or an electron beam evaporation method; then turning over one side of the device after growing the aluminum-doped zinc oxide layer 3 on the upper side, growing the aluminum-doped zinc oxide layer 3 on the surface of the lower part of the substrate layer 1 in the anode position of the substrate layer 1 in the same way as growing the aluminum-doped zinc oxide layer 3 on the surface of the upper metal electrode.

[0076] Adjusting the placement direction of the current device after growing the third metal electrode 23, placing the current device on a metal mask, and depositing the aluminum-doped zinc oxide layer 3 around the anode of the current device by designing the size. The length of the aluminum-doped zinc oxide layer 3 is controlled to be 100 μm-500 μm, and the thickness is controlled to be 100 nm-200 nm.

[0077] First, the magnetron sputtering device is pumped to a high vacuum state, and then a resistance wire is used to heat the substrate layer 1. It is maintained at 300°C during the coating process, the sputtering power is controlled to be 90W, and the argon flow rate is controlled to be 15-20sccm. At this time, the cavity pressure in the magnetron sputtering device is 7mTorr. After growing one side of the aluminum-doped zinc oxide layer 3, open the magnetron sputtering device, turn over the device after growing one side of the aluminum-doped zinc oxide layer 3, and sputter the other side of the aluminum-doped zinc oxide layer 3 according to the same sputtering method.

[0078] S206, growing a silicon nitride layer 4 on the surface of the two aluminum-doped zinc oxide layers 3, the two parts of the substrate layer 1 in the anode position, and the two parts of the substrate layer 1 in the cathode position of the substrate layer 1 by a magnetron sputtering method or an electron beam evaporation method.

[0079] Wherein, the cathode position is the position on the other side of the substrate layer 1.

[0080] Specifically, Figure 3 The preparation process of the longitudinal type light guide switch with electrode expansion structure is schematically shown, wherein, Figure 3 (g) is a schematic view of growing the silicon nitride layer 4 on the surface of the upper metal electrode, Figure 4(h) is a schematic diagram of growing a silicon nitride layer 4 on the surface of the lower metal electrode, by shielding through a metal mask or photoresist, using a magnetron sputtering method or an electron beam evaporation method, to grow a silicon nitride layer 4 on the surface of the upper aluminum-doped zinc oxide layer 3, the upper part of the substrate layer 1 in the anode position, the surface of the upper part of the substrate layer 1 in the cathode position of the substrate layer 1; then flip one side of the device after growing the silicon nitride layer 4 on the upper side, and grow a silicon nitride layer 4 on the surface of the lower aluminum-doped zinc oxide layer 3, the lower part of the substrate layer 1 in the anode position, the surface of the lower part of the substrate layer 1 in the cathode position of the substrate layer 1 in the same way as growing a silicon nitride layer 4 on the surface of the upper metal electrode.

[0081] Adjust the direction of the device after growing the aluminum-doped zinc oxide layer 3, replace the new metal mask, and deposit a silicon nitride layer 4 around the anode and cathode of the device after growing the aluminum-doped zinc oxide layer 3 by designing the size. The length of the silicon nitride layer 4 is controlled to be 600-1000 μm, and the thickness is controlled to be 50-150 nm. First, the magnetron sputtering device is pumped to a high vacuum state, the sputtering power is controlled to be 70-90 W, the argon flow is 10-15 scccm, and 1-3 sscm of nitrogen is introduced at the same time, at this time the cavity pressure of the magnetron sputtering device is 7 mTorr. After growing a silicon nitride layer 4 on one side, open the magnetron sputtering device, flip the device after growing a silicon nitride layer 4 on one side, and sputter another silicon nitride layer 4 according to the same sputtering method.

[0082] S207, apply nano-silver paste on the third metal electrode 23 and connect a copper strip, sinter at a predetermined temperature, form a silver contact between the third metal electrode 23, the nano-silver paste and the copper strip, and encapsulate the device after forming the silver contact with epoxy resin to complete the preparation of the longitudinal type photoconductive switch with electrode expansion structure.

[0083] The predetermined temperature is 230°C.

[0084] Specifically, nano-silver paste is applied on the first metal electrode 21, the second metal electrode 22 and the third metal electrode 23, and then a copper strip is placed. Under the condition of high-temperature sintering at 230°C and 1h, the organic matter in the solvent evaporates to form a relatively good silver contact. Finally, the device after forming the silver contact is placed in a gum tube shell, and epoxy resin AB glue is filled to prepare a longitudinal type photoconductive switch with electrode expansion structure.

[0085] The application provides a preparation method of a longitudinal photoconductive switch with an electrode extension structure.

[0086] Figure 4 The figure schematically shows the electric field intensity distribution of the longitudinal photoconductive switch with the electrode extension structure under the light condition, and the horizontal and vertical coordinates are both the size of the longitudinal photoconductive switch device, in um, see Figure 5 is the simulation of the two-dimensional electric field intensity distribution of the longitudinal photoconductive switch with the electrode extension structure, the bias voltage is set to 5kV, and the light energy is 18e5 W / cm 2 The color depth represents the electric field intensity. Figure 5 The figure schematically shows the electric field intensity distribution of the transverse heterogeneous photoconductive switch under the light condition, and the horizontal and vertical coordinates are both the size of the longitudinal photoconductive switch device, in um, see Figure 4 is the simulation of the two-dimensional electric field intensity distribution of the transverse heterogeneous photoconductive switch, the bias voltage is set to 5kV, and the light energy is 18e5 W / cm 2 The color depth represents the electric field intensity. Figure 6 The color is relatively balanced, the electric field distribution is further balanced, and the stability and reliability of the photoconductive switch device are improved.

[0087] ​ The figure schematically shows the comparison of the actual output signals of the longitudinal photoconductive switch with the electrode extension structure and the transverse heterogeneous photoconductive switch under the same condition, the horizontal coordinate is time, the vertical coordinate is the output pulse voltage amplitude, the red line represents the output signal of the transverse heterogeneous photoconductive switch, and the black line represents the output signal of the longitudinal photoconductive switch with the electrode extension structure according to the application. The bias voltage of the longitudinal photoconductive switch with the electrode extension structure is 5kV, the output light energy is 17mJ, the load resistance is 100Ω, and the electrode gap of the two switches is 4mm.

[0088] Compared with other prior art, the present application has the following advantages: 1. By rapid annealing, the metal nickel and the silicon carbide substrate layer 1 form a good ohmic contact. 2. The metal titanium well connects the metal gold and the metal nickel, so that the electrode has better stability and adhesion. 3. The aluminum-doped zinc oxide layer 3 is used as the first layer of field plate, which is first used as a transparent conductive film. Under the use of a suitable field plate structure, the electrode edge electric field is dispersed, and the risk of switch breakdown is reduced. Secondly, by selecting a suitable thickness, the laser can be better antireflection, so as to achieve the effect of collecting more photons to generate more photo-generated carriers, thereby improving the laser absorption capacity of the photoconductive switch. 4. The silicon nitride layer 4 is used as the second layer of field plate, which can first be used as a passivation layer to suppress surface flashover between the metal electrodes 2 and improve the withstand voltage capacity of the switch; then it can also be used as an antireflection film to absorb more photons, thereby improving the current-carrying capacity of the photoconductive switch. 5. By setting the longitudinal electrode, the electric field distribution is further balanced, and the stability and reliability of the photoconductive switch device are improved.

[0089] It should be pointed out here that the description of the preparation method of the longitudinal photoconductive switch with electrode expansion structure in the above embodiment is similar to the description of the longitudinal photoconductive switch with electrode expansion structure in the above embodiment, and has similar beneficial effects as the longitudinal photoconductive switch with electrode expansion structure in the above embodiment. For technical details not disclosed in the embodiment of the preparation method of the longitudinal photoconductive switch with electrode expansion structure of the present application, please refer to the description of the longitudinal photoconductive switch with electrode expansion structure of the present application for understanding.

[0090] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A longitudinal photoconductive switch with an electrode extension structure, characterized in that, It includes a substrate layer, metal electrodes, an aluminum-doped zinc oxide layer, and a silicon nitride layer; The metal electrodes are formed on the side surfaces at both ends of the substrate layer; The zinc oxide aluminum-doped layer is formed at the anode position of the substrate and is symmetrically distributed on part of the light-incident surface and part of the back-light surface of the substrate. The anode position is a position on one side of the substrate. The silicon nitride layer is formed at the anode and cathode positions of the substrate and is symmetrically distributed on part of the light-incident surface and part of the back-light surface of the substrate. The silicon nitride layer at the anode position is also symmetrically distributed on the zinc oxide aluminum-doped layer. The cathode position is located on the other side of the substrate.

2. The longitudinal photoconductive switch with an electrode extension structure according to claim 1, characterized in that, The metal electrode includes a first metal electrode, a second metal electrode, and a third metal electrode, which are stacked sequentially on the sides of both ends of the substrate layer.

3. The longitudinal photoconductive switch with an electrode extension structure according to claim 2, characterized in that, The first metal electrode is made of nickel and has a thickness ranging from 180 to 220 nm. The second metal electrode is made of titanium and has a thickness ranging from 100 to 140 nm. The third metal electrode is made of gold and has a thickness ranging from 50 to 150 nm.

4. The longitudinal photoconductive switch with an electrode extension structure according to claim 1, characterized in that, The metal electrode, the aluminum-doped zinc oxide layer, and the silicon nitride layer at the cathode position are all rectangular in shape.

5. The longitudinal photoconductive switch with an electrode extension structure according to claim 1, characterized in that, The substrate layer is made of silicon carbide, and the resistivity of the substrate layer is >10. 9 Ω·cm, with a thickness range of 1mm-2mm.

6. The longitudinal photoconductive switch with an electrode extension structure according to claim 1, characterized in that, The edge corner of the zinc oxide aluminum-doped layer is a 90° arc.

7. The longitudinal photoconductive switch with an electrode extension structure according to claim 1, characterized in that, The doping concentration range of the zinc oxide aluminum-doped layer is 1x10⁻⁶. 14 -1x10 17 cm -3 The resistivity of the zinc oxide aluminum-doped layer ranges from 10 Ω·cm to 100 Ω·cm, and the thickness ranges from 100 to 200 nm.

8. The longitudinal photoconductive switch with an electrode extension structure according to claim 1, characterized in that, The resistivity of the silicon nitride layer is >10. 6 Ω·cm, with a thickness range of 100-200nm.

9. A method for fabricating a longitudinal photoconductive switch with an electrode extension structure, characterized in that, The longitudinal photoconductive switch with an electrode extension structure according to any one of claims 1-8 comprises: The substrate layer, made of silicon carbide, was cleaned using the RCA standard cleaning method. A first metal electrode is fabricated on the sides of both ends of the substrate in the electrode region of the substrate using magnetron sputtering or electron beam evaporation, wherein the material of the first metal electrode is nickel. The first metal electrode and the substrate layer are formed into a nickel-silicon alloy by means of RTP rapid annealing. Using magnetron sputtering or electron beam evaporation, a second metal electrode and a third metal electrode are sequentially grown on the first metal electrode after rapid annealing on both sides. The material of the second metal electrode is titanium, and the material of the third metal electrode is gold. After adjusting the placement direction of the current device after growing the third metal electrode, the placement direction of the current device is perpendicular to the placement direction of the substrate layer. Then, using the magnetron sputtering method or the electron beam evaporation method, a zinc oxide aluminum-doped layer is grown on the surface of the substrate layer on both sides of the anode position of the substrate layer. The anode position is the position on one side of the substrate layer. Using the magnetron sputtering method or the electron beam evaporation method, a silicon nitride layer is grown on the surface of the zinc oxide aluminum-doped layer on both sides, the substrate layer on both sides of the anode position, and the substrate layer on both sides of the cathode position, wherein the cathode position is the position on the other side of the substrate layer; Nano-silver paste is coated on the third metal electrode and connected to a copper strip. The electrode is then sintered at a preset temperature to form a silver contact between the third metal electrode, the nano-silver paste, and the copper strip. The device with the silver contact is then encapsulated with epoxy resin to complete the fabrication of the longitudinal photoconductive switch with an electrode extension structure.

10. The method for fabricating a longitudinal photoconductive switch with an electrode extension structure according to claim 9, characterized in that, The doping concentration range of the zinc oxide aluminum-doped layer is 1x10⁻⁶. 14 -1x10 17 cm -3 The resistivity of the zinc oxide-aluminum-doped layer ranges from 10 Ω·cm to 100 Ω·cm, and the thickness ranges from 100 to 200 nm. The resistivity of the silicon nitride layer is >10 Ω·cm. 6 Ω·cm, with a thickness range of 100-200nm.

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