Plasmon electrode photodetector suitable for non-polarized light

Abstract

Provided is an annular interdigital array plasmon electrode photodetector suitable for non-polarized light. The device comprises: a bottom substrate; a semiconductor layer, disposed above the substrate; annular interdigital electrode arrays, disposed above the semiconductor layer, the annular interdigital array electrodes being electrically connected by means of electrode connecting lines among the arrays; and rectangular electrodes, arranged on the left and right sides of the annular interdigital array electrodes, the rectangular electrodes on both sides respectively constituting a positive electrode and a negative electrode of the detector and being used for applying a bias voltage to the detector, the positive and negative electrodes on both sides being connected to the annular interdigital array electrodes by means of the electrode connecting lines, and the annular electrode arrays and the electrode connecting lines forming an annular interdigital electrode array structure. By means of adjusting the radii and the arrangement form of the inner and outer circles of annular electrodes, the effect of the device being insensitive to polarization of incident light is achieved, and the absorption efficiency for the incident light and the bandwidth of the detector are improved.

Description

Plasmonic electrode photodetector for unpolarized light Technical Field

[0001] The present invention belongs to the technical field of optoelectronic devices, and mainly relates to a plasmon electrode photodetector structure suitable for non-polarized light. Background Art

[0002] Photodetectors are devices that convert light signals into electrical signals using the photoelectric effect and have a wide range of applications. Based on their operating wavelengths, they can be categorized into three categories: infrared, visible light, and ultraviolet. Infrared detectors, the most common, are widely used in critical fields such as infrared imaging, night vision devices, space exploration, security detection, and biomedicine. Consequently, research on these detectors is extremely active. A variety of materials are available for infrared detectors, including HgCdTe, InGaAs, GaAs, and Si. GaAs semiconductor materials offer advantages such as a direct band gap, high electron mobility, high-temperature resistance, low power consumption, and a broad absorption spectrum from the ultraviolet to the near-infrared. InGaAs materials, by modifying the InP composition, can detect incident light in the 1-3μm range. These materials, with their mature process technology and compact size, are widely used in the field of light detection. However, these photodetectors still suffer from several drawbacks, including low absorption efficiency of the semiconductor material itself, low photoelectric conversion efficiency, and a narrow device bandwidth.

[0003] Recent research has shown that surface plasmons, generated by metallic nanostructures under illumination, can localize light fields on the metal surface, achieving significant field enhancement. This can effectively improve the response performance of photodetectors. However, photodetectors based on interdigitated and grating structures have a strong dependence on the polarization of the incident light, which is a major limitation to their development.

[0004] For example, external environmental stimulation can cause polarization changes in semiconductor lasers and fiber lasers. In addition, when the optical fiber is coupled with an ordinary single-mode fiber, the polarization cannot remain consistent. In addition, millimeter-wave noise can be obtained by shaping and filtering the ASE broadband light source through an optical filter and then inputting the filtered spectrum into a high-speed photodetector. The polarization direction of the light output by the broadband light source is difficult to control. Detectors suitable for incident light with different polarizations can increase the absorption efficiency of the incident light and improve the output power.

[0005] Therefore, it is very important to develop a photodetector suitable for non-polarized light.

[0006] Summary of the Invention

[0007] The purpose of the present invention is to provide a circular interdigital array electrode photodetector structure suitable for unpolarized light. The circular interdigital array electrode can stimulate the localized surface plasmon effect independently of the polarization of the incident laser, thereby solving the problems of photodetectors using grating structure electrodes being sensitive to the polarization of the incident light and having low absorption efficiency. At the same time, under the same transmission distance, the capacitance of the active region of the device is reduced, the dark current is reduced, and the RC bandwidth of the device is increased, thereby increasing the total bandwidth of the detector.

[0008] Based on the above objectives, the present invention adopts the following technical solutions:

[0009] A plasmon electrode photodetector suitable for unpolarized light comprises: a substrate, a semiconductor layer, an electrode layer, and an anti-reflection layer; the electrode layer comprises a circular interdigitated array electrode, left and right positive and negative electrodes; the circular interdigitated array electrode comprises a circular electrode and a circular electrode connecting wire.

[0010] Furthermore, the circular interdigital array electrodes are connected by circular electrode connecting lines and placed between the positive and negative electrodes. The circular electrode array can be divided into two types according to different arrangements: a staggered distribution type and an aligned distribution type.

[0011] Furthermore, an ohmic contact or a Schottky contact is formed between the electrode layer and the semiconductor layer. When the circular interdigitated array electrode structure is subjected to the incident light field, the free electrons on the surface of the metal electrode will be excited. When the plasmon resonance conditions are met, a local electric field enhancement will be generated around the metal electrode, thereby increasing the absorption efficiency of the semiconductor layer to the incident light and improving the responsiveness.

[0012] Furthermore, the circular interdigitated array electrode electrically connects the circular electrode structure to the left and right positive and negative electrodes through circular electrode connecting lines. The polarity of each adjacent row of circular electrodes is opposite. When the device is irradiated with incident light of different polarization directions, the absorption rate of the semiconductor layer remains stable.

[0013] Furthermore, for the staggered distribution structure, the minimum spacing between any ring and its adjacent rings is equal; by reducing the distance between adjacent rings, the transport distance is shortened and the carrier transport bandwidth of the detector is improved; for the aligned distribution structure, the rings are arranged in a regular rectangular array, and the transport distance is shortened and the transport bandwidth is improved by reducing the spacing between each row.

[0014] Furthermore, the electrode layer is made of Ti, Al, Ni, Ge, Au, Ag or alloys thereof.

[0015] Furthermore, the semiconductor layer is made of GaAs, InGaAs, InGaAs / InAlAs superlattice material, ErAs:In(Al)GaAs, etc.

[0016] Furthermore, the antireflection film is made of SiNx, SiOx, etc.

[0017] In addition, the present invention also proposes a method for preparing a circular interdigital array plasmon electrode photodetector suitable for unpolarized light, comprising the following steps:

[0018] Step 1: growing an epitaxial layer on a temporary substrate using metal organic chemical vapor deposition or molecular beam epitaxy;

[0019] Step 2: Photolithography, metal evaporation, and metal stripping are performed on the surface of the epitaxial layer to form a circular array electrode, electrode connecting lines, and left and right positive and negative electrodes;

[0020] Step 3: performing photolithography and etching on the above structure to form a mesa structure, thereby obtaining a mesa semiconductor epitaxial layer, wherein the upper surface of the semiconductor epitaxial layer is covered with the metal electrode layer obtained in step 2;

[0021] Step 4: Photolithography and metal evaporation to form a coplanar waveguide electrode that contacts the left and right positive and negative electrodes to form an electrical connection for subsequent packaging wire bonding.

[0022] The present invention provides a plasmon electrode photodetector structure suitable for unpolarized light. The structure comprises, from bottom to top, a substrate placed at the bottom, which can be a semiconductor material with high thermal conductivity, such as Si, InP, or GaAs; a semiconductor layer placed above the substrate. When the semiconductor layer is irradiated by light, when the incident light energy is greater than the band gap width of the semiconductor layer material, the semiconductor absorbs the photon energy to generate electron-hole pairs, and transports the photogenerated carriers to electrodes on both sides under an external bias electric field, thereby collecting the photocurrent at the electrodes. It is further specified that the semiconductor layer material can be GaAs, InGaAs, InGaAs / InAlAs superlattice material, ErAs:In(Al)GaAs, or other semiconductor materials.

[0023] The electrode layer placed above the semiconductor layer includes a circular electrode array, left and right positive and negative electrodes, and electrode connecting lines. The electrode layer forms an ohmic contact or a Schottky contact with the semiconductor layer. The circular electrode array and the electrode connecting lines are placed between the left and right positive and negative electrodes. The circular electrode array is arranged according to a specific period, and the number of circular ring structures in each row is the same, which can form two distribution types, namely: aligned distribution type, that is, the circular electrodes in each row are aligned; staggered distribution type, that is, the circular electrodes between each row are staggered with each other, and the circular electrodes in each row are connected by electrode connecting lines and connected to the positive electrode or negative electrode on one side, and the circular electrodes between adjacent rows are connected to square electrodes on different sides.

[0024] When incident light strikes the metal nanostructure, the free electrons on its surface are excited. When the frequencies of the light and free electrons coincide, resonance occurs. This phenomenon, in which surface plasmons are localized on the surface surrounding the metal nanostructure, is called localized surface plasmon (LSPR). The circular ring structure can localize incident light of different polarization directions on its internal metal surface and generate field enhancement, which can significantly improve the semiconductor layer's absorption of incident light.

[0025] In order to improve the device bandwidth performance, the detector bandwidth is mainly determined by two variables, namely the carrier transport time and the RC time constant. The detector bandwidth formula can be expressed as:

[0026] Among them, τ trans is the carrier transport time, τ RC is the RC time constant.

[0027] For the same material, the carrier transport time is determined by the transport distance. When the electrode transport distance decreases, the carrier transport time will be shortened. However, the reduction in electrode distance will lead to an increase in the capacitance of the device active area, resulting in an increase in the RC time constant. Therefore, there is a restrictive relationship between the reduction in transport distance and the increase in bandwidth.

[0028] The RC time constant is related to the capacitance of the active area of ​​the detector. For a detector with interdigital electrodes, the capacitance formula can be expressed as follows:

[0029] Among them, ε r is the relative dielectric constant of the semiconductor, A is the detection area of ​​the detector, P is the period of the interdigitated electrodes, K(k) is the complete elliptic integral of the first kind,

[0030] Among them, w is the electrode width, and the ratio of w to P is the duty cycle of the interdigitated electrode. According to the formula, when the other variables are constant, the larger the duty cycle, the greater the capacitance of the detector.

[0031] Compared with the traditional interdigital electrode structure, the circular interdigital array electrode proposed in the present invention has an average duty cycle smaller than that of the interdigital electrode when the interdigit length and transmission distance are the same, thereby obtaining a smaller active area capacitance and increasing the bandwidth of the detector.

[0032] The electrode layer material can be one or a combination of high conductivity metals such as Ti, Al, Ni, Ge, Au, Cr, etc.

[0033] The left and right positive and negative electrodes are connected to an external positive electrode on one side and a negative electrode on the other side for applying a bias voltage to the detector;

[0034] The antireflection film covers the semiconductor and electrode layers, and the antireflection film is made of dielectric materials such as silicon nitride and silicon dioxide.

[0035] The present invention has the following advantages and beneficial technical effects:

[0036] 1) The present invention proposes a plasmon electrode photodetector suitable for unpolarized light, which achieves stable absorption of the photodetector semiconductor layer under different incident light polarization directions, thereby improving the absorptivity and enhancing the detector response bandwidth.

[0037] 2) The present invention proposes a circular array electrode structure, in which each row of circular ring structures is connected by electrode connecting wires, and adjacent rows are electrically connected to the positive and negative electrodes alternately, thereby forming a positive-negative-positive electrode arrangement; compared with traditional interdigitated electrodes, by shortening the spacing between each row of circular ring electrodes, the carrier transport distance is reduced, the carrier transit time is reduced, and the transport bandwidth of the detector is improved; however, the reduction in electrode spacing will lead to an increase in the active area capacitance, thereby affecting the RC bandwidth. The circular array structure can effectively reduce the electrode length at the shortest transport distance, avoid the reduction of the RC bandwidth under the same active area, and improve the response bandwidth of the detector.

[0038] 3) The circular array electrodes proposed in the present invention are arranged according to a certain periodicity. After simulation verification, the circular array electrodes have the advantage of being insensitive to the polarization of the incident light; and under the action of the light field, a local field enhancement is formed at the electrode-semiconductor layer interface, which increases the semiconductor layer's absorption efficiency of the incident light, allowing the electrode to collect more photogenerated carriers and improve the detector's photoelectric conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0040] FIG1 is a schematic diagram of a central cross-section of a unit structure in the non-polarized light photodetector structure proposed in the present invention.

[0041] FIG2 is a top view of a unit structure in the non-polarized light photodetector structure proposed in the present invention.

[0042] FIG3 is a top view of the staggered distribution structure of the non-polarized light photodetector structure proposed in the present invention.

[0043] FIG4 is a top view of the aligned distributed structure of the non-polarized light photodetector structure proposed in the present invention.

[0044] FIG5 is a graph showing how the light absorption rate of the semiconductor layer of the non-polarized light photodetector structure and the interdigitated electrode structure proposed in the present invention changes with the polarization direction.

[0045] FIG6 is a schematic diagram of the electric field of a cross section of a unit structure in the non-polarized light photodetector structure proposed in the present invention.

[0046] FIG7 shows the effect of the bandwidth of the non-polarized light photodetector structure proposed in the present invention on the carrier transport time, as well as the relationship between the bandwidth difference Δf of the two detector structures and the carrier transport time.

[0047] The figure marks are: 1: the transmittance-enhancing layer of the non-polarized light photodetector structure; 2: the electrode layer of the non-polarized light photodetector structure; 3: the semiconductor layer of the non-polarized light photodetector structure; 4: the substrate of the non-polarized light photodetector structure; 5: the circular electrode in the electrode layer of the non-polarized light photodetector structure; 6: the electrode connecting line in the electrode layer of the non-polarized light photodetector structure. DETAILED DESCRIPTION

[0048] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0049] The present invention discloses a plasmon electrode photodetector structure suitable for unpolarized light and a preparation method thereof. The device structure includes a substrate at the bottom; a semiconductor layer placed above the substrate; a circular interdigital electrode array placed above the semiconductor layer, the circular interdigital array electrodes being electrically connected via electrode connecting lines between the arrays; rectangular electrodes placed on the left and right sides of the circular interdigital array electrodes, the square electrodes on both sides respectively constituting the positive and negative electrodes of the detector, and being used to apply a bias voltage to the detector, the positive and negative electrodes on both sides being connected to the circular interdigital array electrodes via electrode connecting lines, and the circular electrode array and the electrode connecting lines constituting a circular interdigital electrode array structure.

[0050] The non-polarized light photodetector structure based on the circular interdigital array electrode proposed in the present invention achieves the polarization insensitivity of the device to the incident light by adjusting the inner and outer circle radii and the arrangement of the circular electrodes, thereby improving the absorption efficiency of the incident light and the bandwidth of the detector.

[0051] FIG1 is a schematic diagram of a central cross-section of a unit structure in a non-polarized light photodetector structure proposed according to an exemplary embodiment. Referring to FIG1 , an embodiment of the present invention provides a non-polarized light photodetector structure, comprising: a transmittance-enhancing layer 1 of the non-polarized light photodetector structure, an electrode layer 2 of the non-polarized light photodetector structure, a semiconductor layer 3 of the non-polarized light photodetector structure, a substrate 4 of the non-polarized light photodetector structure, a circular electrode 5 in the electrode layer of the non-polarized light photodetector structure, and an electrode connection line in the electrode layer of the non-polarized light photodetector structure. The transmittance-enhancing layer 1 of the non-polarized light photodetector structure is placed on the electrode layer 2 and the semiconductor layer 3 to increase the transmission of incident light and reduce reflection; the electrode layer 2 is placed between the transmittance-enhancing layer 1 and the semiconductor layer 3, and includes a circular interdigitated array electrode, left and right positive and negative electrodes, and the circular interdigitated electrode array includes the circular electrode 5 and the electrode connection line 6.

[0052] The semiconductor layer 3 is placed between the annular interdigitated array electrode 2 and the substrate 4, and is used to absorb incident light and generate photogenerated electron-hole pairs inside it. Under the action of an external bias voltage, electrons drift toward the positive electrode and holes drift toward the negative electrode, which are collected by the electrodes and form photocurrent output.

[0053] FIG2 is a top view of a unit structure in a non-polarized light photodetector structure proposed in the present invention.

[0054] FIG3 is a top view of a staggered distribution structure of a non-polarized light photodetector structure proposed in the present invention.

[0055] FIG4 is a top view of an aligned distributed structure of a non-polarized light photodetector structure proposed in the present invention.

[0056] FIG5 is a graph showing the variation of light absorption rate of the semiconductor layer of a non-polarized light photodetector structure and an interdigitated electrode structure as the polarization direction is changed in the present invention.

[0057] FIG6 is a schematic diagram of an electric field cross-section of a unit structure of a non-polarized light photodetector structure proposed in the present invention.

[0058] FIG7 shows the effect of carrier transport time on the bandwidth of a non-polarized light photodetector structure proposed in the present invention, as well as the effect of bandwidth difference and carrier transport time when the active region capacitance of the detector is different.

[0059] The structure of the non-polarized light photodetector in the present invention is described with reference to FIG1 , FIG2 , FIG3 , FIG4 , FIG5 , FIG6 and FIG7 .

[0060] As can be seen from the above embodiments, the circular interdigitated array electrode structure proposed by the present invention uses a circular interdigitated electrode structure to achieve a certain absorption efficiency of the semiconductor layer for incident light of different polarization directions. A specific circular structure period is obtained through simulation. Under the action of the light field, the metal-semiconductor surface will produce local field enhancement, thereby improving the photoelectric conversion efficiency of the detector. Adjacent rows of the circular interdigitated array electrode structure are in contact with the positive and negative electrodes respectively. For the staggered structure, shortening the distance between the circular structures in the same row can shorten the distance of carrier transport, thereby improving the carrier transport bandwidth of the device. The circular interdigitated array electrode can reduce the area between the positive and negative electrodes at the shortest transport distance. Under the same active area, the capacitance of the active area of ​​the device is reduced, avoiding the problem of capacitance increase due to distance shortening, and increasing the RC bandwidth of the detector. In this way, the bandwidth of the detector is improved.

[0061] Among them, by shortening the distance between the circular ring structures in the same row, the distance of carrier transport can be shortened, and by designing the spacing between adjacent circular ring structures, the plasmon resonance enhancement of adjacent circular rings at a specific wavelength can be achieved.

[0062] In this embodiment, the semiconductor material can be indium gallium arsenide (InGaAs) or gallium arsenide (GaAs). GaAs and InGaAs semiconductor materials have the characteristics of short carrier lifetime, high mobility, high resistivity, and coverage of the communication frequency band, and are therefore used as the semiconductor layer of the photodetector.

[0063] In this embodiment, FIG1 is a schematic diagram of a central cross-section of a unit structure in a non-polarized light photodetector structure proposed according to an exemplary embodiment.

[0064] Specifically, the photoelectric detection response wavelength designed in this embodiment is in the C band. The substrate thickness b is typically greater than 50 microns, the semiconductor layer thickness c is set to 1 to 3 microns, the electrode layer thickness h1 is 200-270 nanometers, the inner diameter w of the annular electrode is 0.4-0.5 microns, and the difference r between the outer and inner radii of the annular electrode is 0.65-0.7 microns (i.e., the annular wall thickness is 0.65-0.7 microns).

[0065] Preferably, taking 1550nm InGaAs as the semiconductor layer as an example, the electrode layer material used is Au, the substrate material used is InP, the anti-reflection layer material used is Si3N4, and the parameters are a=3.34μm, c=1μm, d=0.5μm, h1=0.25μm, h2=0.164μm, w=0.98μm, r=0.68μm, and the simulated incident light wavelength is selected as lambda=1550nm.

[0066] Figure 5 shows the light absorption rate curves of the semiconductor layer of an unpolarized light photodetector structure and an interdigitated electrode structure for incident light at different polarization angles, according to exemplary embodiments. The light absorption rate of the semiconductor layer varies with the polarization angle of the incident light, as shown in Figure 5. Compared to the interdigitated electrode structure, the structure of the present invention achieves an absorption rate exceeding 70% for incident light from all directions, significantly enhancing the device's absorption efficiency for incident light of varying polarization directions and improving light utilization.

[0067] Figure 6 is a schematic diagram of the electric field of a unit structure cross section of a non-polarized light photodetector structure proposed according to an exemplary embodiment. As can be seen from the figure, in the structure, the local electric field inside the ring is significantly enhanced compared to the interdigitated electrode structure. This is because the incident light irradiates the metal nano-ring structure, and the conduction band free electrons on the metal surface undergo collective motion, causing the surface electron cloud to deviate from the nucleus. At this time, the curved surface of the metal structure exerts an effective restoring force on the collectively moving free electrons, resulting in collective oscillation of electrons near the nucleus, generating a localized surface plasmon resonance (LSPR) phenomenon, causing the light field to be localized at the ring electrode-semiconductor interface and producing a very strong field enhancement effect.

[0068] The bandwidth advantage of the detector structure of the present invention is demonstrated by comparison with a photodetector with an interdigitated electrode structure. When simulating capacitance, with the same minimum transport distance between the positive and negative electrodes and the same electrode finger length, the capacitance values ​​for the two structures were 19.41fF for the interdigitated electrode structure and 11.11fF for the detector structure of the present invention. The capacitance of the unpolarized light photodetector structure is approximately 40% lower than that of the conventional interdigitated electrode structure.

[0069] The device bandwidth for different structures was calculated using the formula, showing that the bandwidth increase for the unpolarized light photodetector compared to the interdigitated electrode structure varies with carrier transport time. At a carrier transport time of 0.6 ps, the bandwidth increase corresponds to Δf = 55 GHz. Figure 7 shows the effect of carrier transport time on the bandwidth of a proposed unpolarized light photodetector structure, as well as the effect of the bandwidth difference Δf between the two structures on carrier transport time.

[0070] According to the absorption spectrum of the incident light at different polarization angles and the cross-sectional electric field enhancement diagram of the above non-polarized light photodetector structure, it can be seen from the results that the designed structure greatly improves the light absorption efficiency of the semiconductor layer, shortens the carrier transport distance, and avoids the decrease of RC bandwidth, thereby achieving the purpose of improving the detector conversion efficiency and increasing the bandwidth.

[0071] Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included in the scope of protection of the claims of the present invention.

Claims

1. A circular interdigital array plasmon electrode photodetector suitable for unpolarized light, characterized in that: include: A substrate, a semiconductor layer, an electrode layer, and an anti-reflection layer; the electrode layer includes a circular interdigital array electrode, left and right positive and negative electrodes; the circular interdigital array electrode includes a circular electrode and a circular electrode connecting wire.

2. A circular interdigital array plasmon electrode photodetector suitable for unpolarized light, characterized in that: include: A substrate, a semiconductor layer, an electrode layer, and an anti-reflection layer; the electrode layer includes a circular interdigital array electrode, left and right positive and negative electrodes; the circular interdigital array electrode includes a circular electrode and a circular electrode connecting wire; The circular interdigital array electrode electrically connects the circular electrode structure to the left and right positive and negative electrodes through circular electrode connecting wires, and each row of adjacent circular electrodes has opposite polarities; An ohmic contact is formed between the electrode layer and the semiconductor layer, and the annular interdigital array electrode meets the plasmon resonance condition.

3. A circular interdigital array plasmon electrode photodetector suitable for unpolarized light, characterized in that: include: Substrate, semiconductor layer, electrode layer, anti-reflection layer; the electrode layer includes a circular interdigital array electrode, left and right positive and negative electrodes; the circular interdigital array electrode includes a circular electrode and a circular electrode connecting line; the circular interdigital array electrode is connected by the circular electrode connecting line and is placed between the positive and negative electrodes; InGaAs with a response wavelength of 1550nm is used as the semiconductor layer, the electrode layer material is Au, the substrate material is InP, and the anti-reflection layer material is Si3N4; the thickness b of the substrate is greater than 50 microns, the thickness c of the semiconductor layer is set to 1-3 microns, the thickness h1 of the electrode layer is 200-270 nanometers, the inner circle diameter w of the circular electrode is 0.4-0.5 microns, and the difference r between the outer circle and the inner circle radius of the circular electrode is 0.65-0.7 microns.

4. The circular interdigital array plasmon electrode photodetector suitable for non-polarized light according to claim 1, characterized in that: The circular interdigital array electrodes are connected by circular electrode connecting lines and are placed between the positive and negative electrodes. The circular electrode array can be divided into two types according to different arrangement modes: staggered distribution type and aligned distribution type.

5. The circular interdigital array plasmon electrode photodetector suitable for non-polarized light according to claim 1, characterized in that: An ohmic contact or a Schottky contact is formed between the electrode layer and the semiconductor layer. When the incident light field occurs, free electrons on the surface of the metal electrode are excited. When the plasmon resonance condition is met, a local electric field enhancement is generated around the metal electrode, thereby increasing the absorption efficiency of the semiconductor layer to the incident light and improving the responsiveness.

6. The circular interdigital array plasmon electrode photodetector suitable for non-polarized light according to claim 1, characterized in that: The circular interdigitated array electrode electrically connects the circular electrode structure to the left and right positive and negative electrodes through circular electrode connecting lines. Each adjacent row of circular electrodes has opposite polarity. When incident light of different polarization directions irradiates the device, the absorption rate of the semiconductor layer remains stable.

7. The circular interdigital array plasmon electrode photodetector suitable for non-polarized light according to claim 1, characterized in that: For the staggered distribution structure, the minimum spacing between any ring and its adjacent rings is equal; by reducing the distance between adjacent rings, the transport distance is shortened and the carrier transport bandwidth of the detector is improved; for the aligned distribution structure, the rings are arranged in a regular rectangular array, and the transport distance is shortened and the transport bandwidth is improved by reducing the spacing between each row.

8. The circular interdigital array plasmon electrode photodetector suitable for non-polarized light according to claim 1, characterized in that: The electrode layer is made of Ti, Al, Ni, Ge, Au, Ag or their alloys.

9. The circular interdigital array plasmon electrode photodetector suitable for non-polarized light according to claim 1, characterized in that: The semiconductor layer is made of GaAs, InGaAs, InGaAs / InAlAs superlattice material, ErAs:In(Al)GaAs, etc.

10. The circular interdigital array plasmon electrode photodetector suitable for non-polarized light according to claim 1, characterized in that: The antireflection film is made of SiNx, SiOx, etc.

11. A method for preparing a circular interdigital array plasmon electrode photodetector suitable for non-polarized light, characterized in that: The following steps are involved: Step 1: growing an epitaxial layer on a temporary substrate using metal organic chemical vapor deposition or molecular beam epitaxy; Step 2: Photolithography, evaporation of metal, and stripping of metal on the surface of the epitaxial layer to form a circular array electrode, electrode connecting wires, and left and right positive and negative electrodes; Step 3: performing photolithography and etching on the above structure to form a mesa structure, thereby obtaining a mesa semiconductor epitaxial layer, wherein the upper surface of the semiconductor epitaxial layer is covered with the metal electrode layer obtained in step 2; Step 4: Photolithography and metal evaporation to form a coplanar waveguide electrode in contact with the left and right positive and negative electrodes to form an electrical connection for subsequent packaging wire bonding.

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