Photoconductive switch of comb-shaped electrode

Abstract

The invention provides a photoconductive switch of a comb electrode, which comprises a semi-insulating gallium arsenide substrate layer, a low-temperature gallium arsenide layer and an insulating protective layer, and is characterized in that the low-temperature gallium arsenide layer is formed on the semi-insulating gallium arsenide substrate layer, and the insulating protective layer is arranged on the low-temperature gallium arsenide layer; a switch anode and a switch cathode are respectively formed on the inner side of the low-temperature gallium arsenide layer surface insulation protection layer; a comb-shaped electrode is arranged on the surface of the low-temperature gallium arsenide layer and located at the switch anode. According to the invention, by arranging the comb-shaped electrode structure, a plurality of comb-tooth electrodes which are distributed in a staggered manner are formed in the electrode region, so that the action area of incident light and a semiconductor active region is increased under an illumination condition, and generation and collection of photon-generated carriers are facilitated; meanwhile, the distribution state of an electric field near the electrode is improved, and the possibility of local electric field concentration is reduced; in addition, a low-temperature gallium arsenide material is adopted as the photoconductive layer, the service life of a current carrier is short, and the device is suitable for photoelectric trigger application scenes with requirements for response speed and stability.

Description

Technical Field

[0001] This invention belongs to the field of photoconductive switch technology, and specifically relates to a photoconductive switch with comb-shaped electrodes. Background Technology

[0002] A photoconductive switch is a semiconductor device that uses light signals to trigger and control the switching of high voltage and high current. It features low jitter, good electromagnetic isolation, and the ability to operate at high repetition rates, and has been widely used in pulse power systems and ultra-high-speed electronics.

[0003] Existing photoconductive switches typically employ a parallel electrode structure, which has the following drawbacks in practical applications: The uneven electric field distribution at the electrode edge can easily lead to local electric field concentration, which can cause premature breakdown and affect the reliability of the device. The electrode structure has limited utilization of incident light and low efficiency in generating photogenerated carriers, resulting in high on-resistance and limited response speed.

[0004] Therefore, there is still a need in the prior art to provide a photoconductive switch with improved structure to improve light utilization conditions and optimize the electric field distribution in the electrode region.

[0005] Based on this, a photoconductive switch with comb-shaped electrodes is proposed. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a photoconductive switch with comb-shaped electrodes to address the shortcomings of the prior art mentioned above.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a photoconductive switch with comb-shaped electrodes, comprising: a semi-insulating gallium arsenide substrate layer, a low-temperature gallium arsenide layer, and an insulating protective layer. The low-temperature gallium arsenide layer is formed on the top surface of the semi-insulating gallium arsenide substrate, and the insulating protective layer is disposed on the low-temperature gallium arsenide layer; A switching anode and a switching cathode are formed on the inner side of the insulating protective layer on the surface of the low-temperature gallium arsenide layer; a comb-shaped electrode is also provided on the surface of the low-temperature gallium arsenide layer at the switching anode.

[0008] As a further illustration of the present invention, the insulating protective layer is made of silicon nitride.

[0009] As a further illustration of the present invention, the switching anode, switching cathode, and comb-shaped electrode are all made of alloy materials.

[0010] As a further explanation of the present invention, the alloy material is specifically an Au / Ge / Ni alloy.

[0011] As a further explanation of the present invention, the comb-shaped electrode has 150 comb teeth electrodes, and the ratio of the width of the comb teeth electrode to the gap width between adjacent comb teeth electrodes is 1:1.

[0012] Compared with the prior art, the present invention has the following advantages: This invention utilizes a comb-shaped electrode structure at the switching anode on the surface of a low-temperature gallium arsenide layer. This structure creates multiple staggered comb-shaped electrodes within the electrode region, thereby increasing the interaction area between the incident light and the active region of the semiconductor under illumination, which is beneficial for the generation and collection of photogenerated carriers. Simultaneously, the comb-shaped electrode structure helps improve the electric field distribution near the electrodes, reducing the possibility of local electric field concentration. Furthermore, the use of low-temperature gallium arsenide material as the photoconductive layer results in a shorter carrier lifetime, making it suitable for obtaining photoconductive switching devices with fast response times. This is applicable to photoelectric triggering applications where response speed and stability are required. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a front view of the overall structure of the present invention; Figure 3 This is a top view of the overall structure of the invention; Figure 4 This is a schematic diagram of the state used in the experimental examples of this invention; Figure 5 This is a test diagram from an experimental example of the present invention.

[0014] Explanation of reference numerals in the attached figures: 1. Semi-insulating gallium arsenide substrate; 2. Low-temperature gallium arsenide layer; 3. Insulating protective layer; 4. Switch anode; 5. Switch cathode; 6. Comb electrode; 7. Laser beam; 8. Adjustable high-voltage power supply; 9. Protective resistor; 10. Capacitor; 11. Switch body; 12. Coaxial transmission line; 13. Attenuator; 14. Oscilloscope. Detailed Implementation

[0015] To make the technical problems, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the described embodiments are only a part of the embodiments of this application, not all of them. The specific embodiments described herein are only used to explain the invention and are not intended to limit the invention. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0016] like Figure 1-3As shown, the present invention provides a technical solution: a photoconductive switch with comb-shaped electrodes, comprising: a semi-insulating gallium arsenide substrate 1, a low-temperature gallium arsenide layer 2, and an insulating protective layer 3, wherein the low-temperature gallium arsenide layer 2 is formed on the top surface of the semi-insulating gallium arsenide substrate 1, and the insulating protective layer 3 is disposed on the low-temperature gallium arsenide layer 2, and the insulating protective layer 3 is made of silicon nitride. In this embodiment, the resistivity of both the semi-insulating gallium arsenide layer 1 and the low-temperature gallium arsenide layer 2 is 1×10⁻⁶. 8 The thickness of the semi-insulating gallium arsenide layer 1 is 597 μm, and the thickness of the low-temperature gallium arsenide layer 2 is 2 μm.

[0017] A switching anode 4 and a switching cathode 5 are formed on the inner side of the insulating protective layer 3 on the surface of the low-temperature gallium arsenide layer 2; a comb-shaped electrode 6 is also provided on the surface of the low-temperature gallium arsenide layer 2 at the location of the switching anode 4.

[0018] Specifically, the switching anode 4, the switching cathode 5, and the comb-shaped electrode 6 are all made of alloy material, specifically Au / Ge / Ni alloy.

[0019] Specifically, a nickel layer with a thickness of 50 nm, a gold layer with a thickness of 400 nm, and a germanium layer with a thickness of 200 nm are sequentially deposited on the low-temperature gallium arsenide layer 2 by electron beam evaporation. Then, a rapid thermal annealing process is performed, which is held at a constant temperature of 300°C for 60 seconds to form an ohmic contact between the alloy mixture and the low-temperature gallium arsenide layer 2, thereby forming a switching anode 4, a switching cathode 5, and a comb-shaped electrode 6.

[0020] The comb-shaped electrode 6 has 150 comb teeth electrodes, and the ratio of the width of the comb teeth electrode to the gap width between adjacent comb teeth electrodes is 1:1. Specifically, each comb electrode has a width of 10 μm, and the gap width between adjacent comb electrodes is 10 μm.

[0021] Experimental examples, such as Figure 4 As shown, the adjustable high voltage power supply 8 adopts a 0~3kV adjustable high voltage power supply, the protection resistor 9 is 1MΩ, the capacitor 10 is 50pF, the power attenuation of the attenuator 13 is 60dB, and the bandwidth of the oscilloscope 14 is 33GHz. The aforementioned comb-shaped electrode photoconductive switch first uses an adjustable high-voltage power supply 8 (0-3kV), which charges the capacitor 10 through a protective resistor 9. Secondly, a wire connects the switch anode 4 and the switch cathode 5.

[0022] In the dark state, the switch has no output because the resistance of the photoconductive switch on the comb electrode 6 is on the order of GΩ. When the switch body 11 is excited by the laser beam 7, a large number of photogenerated carriers are generated, and the circuit is turned on. The switch output is connected to the attenuator 13 via the coaxial transmission line 12 and captured by the oscilloscope 14.

[0023] The results are as follows Figure 5 As shown, when the bias voltages of the adjustable high-voltage power supply 8 are 1.2kV, 1.8kV and 2.2kV, the peak voltages of the output electrical pulses are 0.44kV, 0.60kV and 0.85kV, respectively, and the pulse widths are 36.557ps, 35.062ps and 34.002ps, respectively.

[0024] As the bias voltage increases, the electric field strength inside the device also increases. The greater the kinetic energy of the photogenerated carriers, the higher the amplitude of the output electric pulse.

[0025] When the bias voltage is 2.2 kV and the optical pulse energy is 193 μJ, the output electrical pulse amplitude reaches 0.85 kV, and the pulse width is 34 ps. The comb-electrode photoconductive switch is made of low-temperature gallium arsenide, with a carrier lifetime of approximately 4 ps. In linear mode, the rise time of the switch's output electrical pulse is determined by the rise time of the optical pulse, which is on the order of ps, while the fall time is determined by the carrier lifetime. Therefore, the switch can output electrical pulses on the order of ps. This electrical pulse can be better applied to fields such as ultra-wideband microwave sources and electronic countermeasures.

[0026] It should be further noted that the accompanying drawings and embodiments of the present invention mainly describe the concept of the present invention. Based on this concept, some specific forms and arrangements of connection relationships, positional relationships, power mechanisms, power supply systems, hydraulic systems and control systems may not be fully described. However, under the premise that those skilled in the art understand the concept of the present invention, they can implement the above-mentioned specific forms and arrangements in a well-known manner.

[0027] When a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0028] The directional terms "inner" and "outer" refer to the inner and outer sides relative to the outline of each component itself. The terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," or "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0029] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways, and the spatial relative descriptions used herein will be interpreted accordingly.

[0030] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, and "several" means one or more, unless otherwise explicitly specified.

[0031] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0032] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A photoconductive switch with comb-shaped electrodes, characterized in that, include: Semi-insulating gallium arsenide substrate (1); A low-temperature gallium arsenide layer (2) is formed on the top surface of the semi-insulating gallium arsenide substrate layer (1); An insulating protective layer (3) is disposed on the low-temperature gallium arsenide layer (2); A switching anode (4) and a switching cathode (5) are formed on the inner side of the insulating protective layer (3) on the surface of the low-temperature gallium arsenide layer (2); a comb-shaped electrode (6) is also provided on the surface of the low-temperature gallium arsenide layer (2) at the location of the switching anode (4).

2. The photoconductive switch with comb-shaped electrodes according to claim 1, characterized in that, The insulating protective layer (3) is made of silicon nitride.

3. The photoconductive switch with comb-shaped electrodes according to claim 1, characterized in that, The switching anode (4), switching cathode (5), and comb electrode (6) are all made of alloy material.

4. A photoconductive switch with comb-shaped electrodes according to claim 3, characterized in that, The alloy material is specifically an Au / Ge / Ni alloy.

5. A photoconductive switch with comb-shaped electrodes according to claim 4, characterized in that, The switching anode (4), switching cathode (5), and comb electrode (6) are formed by sequentially depositing a nickel layer with a thickness of 50 nm, a gold layer with a thickness of 400 nm, and a germanium layer with a thickness of 200 nm on a low-temperature gallium arsenide layer (2) by electron beam evaporation. Then, rapid thermal annealing is performed to make the alloy mixture form an ohmic contact with the low-temperature gallium arsenide layer (2) to form the switching anode (4), switching cathode (5), and comb electrode (6).

6. A photoconductive switch with comb-shaped electrodes according to claim 1, characterized in that, The comb-shaped electrode (6) has 150 comb teeth electrodes, and the ratio of the width of the comb teeth electrode to the gap width between adjacent comb teeth electrodes is 1:1.

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