Backside illuminated InGaAs / InP high-efficiency photoelectric conversion photocell and manufacturing method thereof

Abstract

According to the back-illuminated InGaAs / InP high-efficiency photoelectric conversion photocell and the manufacturing method thereof, a back-illuminated chip structure design is adopted, light enters from the back surface of a substrate, light concentration and uniform distribution are realized through an illumination channel, and photoelectric response is enhanced; the surface of the illuminated fan-shaped area is covered with an antireflection film, so that reflection loss is reduced; a window region adopts an InP material matched with an InGaAs lattice, so that the recombination probability of photon-generated carriers is reduced; the P region and the N region are made of undoped materials, and the thickness of the active region is optimized to improve the photoelectric conversion efficiency; the lightly doped buffer region I and the heavily doped buffer region II realize doping gradient transition and carrier separation efficiency improvement; electrode design is optimized, energy loss is reduced, and contact layout strengthens electric connection; the polyimide insulation protection layer provides electrical isolation and mechanical strength; through collaborative optimization of the structure, the efficiency of light capture, photoelectric conversion and carrier separation and collection is remarkably improved, and excellent photoelectric conversion efficiency can be achieved under the conditions of weak light and high light intensity.

Description

Technical Field

[0001] The invention relates to the technical field of photoelectric conversion, and in particular to a back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell and a manufacturing method thereof. Background Art

[0002] Photoelectric conversion technology is one of the key technologies for converting light energy into electrical energy, and is widely used in the fields of renewable energy utilization, optoelectronic information technology, and optoelectronic detection. In photoelectric conversion technology, photovoltaic cells are core devices, and the optimization of their performance has always been the focus of research.

[0003] At present, although traditional photovoltaic cells such as monocrystalline silicon cells and polycrystalline silicon cells are mature and widely used, their photoelectric conversion efficiency has limited room for improvement and their manufacturing costs are relatively high. With the continuous development of thin-film photovoltaic cell technology, new photovoltaic cells such as dye-sensitized cells, compound cells and silicon-based thin-film cells are gradually emerging. These new photovoltaic cells have the advantages of low manufacturing cost, easy mass production and long service life, but their photoelectric conversion efficiency still needs to be further improved.

[0004] Among thin-film photovoltaic cells, InGaAs / InP photovoltaic cells have become a hot topic of research due to their unique material properties and structural advantages. InGaAs materials have excellent photoelectric conversion performance, while InP materials, as a good substrate material, form a good lattice match with InGaAs, which helps to improve the performance of photovoltaic cells. However, existing InGaAs / InP photovoltaic cells still have some problems in terms of photoelectric conversion efficiency.

[0005] Specifically, traditional InGaAs / InP photovoltaic cells usually adopt a front-incident structure, that is, light is incident from the front of the photovoltaic cell, passes through metal electrodes and other structures, and is then absorbed by the photosensitive material inside the photovoltaic cell. This structure has the problem that the metal electrode blocks part of the incident light, resulting in a decrease in the duty cycle of the photosensitive surface, which in turn affects the photoelectric conversion efficiency. In addition, traditional InGaAs / InP photovoltaic cells also have certain deficiencies in the division of the illumination area, light absorption and conversion efficiency, etc.

[0006] In order to improve the photoelectric conversion efficiency of InGaAs / InP photovoltaic cells, researchers have conducted a lot of exploration and improvement. For example, by optimizing the structural design of photovoltaic cells, improving material selection and preparation process, the performance of photovoltaic cells can be improved. However, these improvement methods often have certain limitations and it is difficult to fundamentally solve the problems of traditional InGaAs / InP photovoltaic cells.

[0007] In summary, the photoelectric conversion efficiency of InGaAs / InP photocells in the prior art still needs to be further improved, especially in terms of photosensitive surface duty cycle, illumination area division, light absorption and conversion efficiency, etc. There are obvious problems and deficiencies. Therefore, a new InGaAs / InP photocell design is urgently needed to solve the problems existing in the prior art, improve the photoelectric conversion efficiency, and promote the further development of photoelectric conversion technology. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell and a manufacturing method thereof, so as to solve the problem of low photoelectric conversion efficiency of InGaAs / InP photovoltaic cells in the field of photoelectric conversion technology, especially the problems of metal electrodes blocking part of the incident light, reduced duty cycle of the photosensitive surface and unreasonable division of the illumination area in traditional front-illuminated structure photovoltaic cells.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is: a back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell, including an illuminated sector-shaped area arranged on a substrate, adopting a back-illuminated structure design, the illuminated sector-shaped area is divided into a number of sector-shaped units by an illumination ditch, the illuminated sector-shaped area is covered with an anti-reflection film, the anti-reflection film is connected to the illuminated sector-shaped area through a number of sector-shaped area connection contacts, a heavily doped buffer II region, a lightly doped buffer I region, an N region, a P region, and a window region are arranged layer by layer below the substrate, each sector-shaped unit is connected through an electrode, and the interior of the battery is filled with a polyimide insulating protective layer to achieve electrical isolation and improve mechanical strength.

[0010] In a preferred solution, the illuminated fan-shaped area is the photosensitive surface of the chip, and the device adopts a back-illuminated chip structure, and light enters from the back of the substrate.

[0011] In a preferred solution, the lighting trench divides the illuminated sector area into a number of sector units, and optimizes the concentration and uniform distribution of light through geometric design.

[0012] In a preferred solution, the geometric design of the lighting trenches includes the depth, width and spacing of the lighting trenches.

[0013] In a preferred solution, the anti-reflection film adopts a multi-layer structure design to enhance the transmission efficiency of light in a wide spectral range and has optical stability. The thickness and refractive index of the anti-reflection film are optimized.

[0014] In a preferred solution, the window region is made of InP material that is lattice-matched to InGaAs.

[0015] In a preferred solution, the P region and the N region are the absorption P region and the N region respectively, which together constitute the active absorption region, and use undoped In0.53Ga0.47As material.

[0016] In a preferred solution, the lightly doped buffer region I is a lightly doped N-type InP layer to achieve doping transition.

[0017] In a preferred embodiment, the heavily doped buffer II region is a heavily doped N-type InP layer, which is used to make the lower electrode contact, realize lateral conduction, and serve as the back surface field of the battery to reduce the recombination rate of photogenerated holes.

[0018] In a preferred embodiment, the electrode is prepared in the heavily doped buffer II region, connected to the window of the fan-shaped unit, providing a conductive channel to collect electrons and transport current.

[0019] The method for manufacturing any one of the above-mentioned back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cells comprises the following steps: Step 1: On the semi-insulating InP substrate, a heavily doped buffer II region, a lightly doped buffer I region, an N region, a P region, and a window region are sequentially grown, and an illuminated fan-shaped region and an illuminated trench are formed by photolithography and etching processes; Step 2: Cover the illuminated sector area with an anti-reflection film; Step 3: Prepare electrodes on the heavily doped buffer II region and achieve physical isolation between unit cells through a wet etching process; Step 4: Apply a polyimide insulating protective layer on the electrode to complete the manufacture of the photovoltaic cell.

[0020] The back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell and the manufacturing method thereof provided by the present invention have the following beneficial effects: 1. Aiming at the problem of low photoelectric conversion efficiency of InGaAs / InP photocells in the field of photoelectric conversion technology, the present invention proposes a back-illuminated InGaAsInP high-efficiency photoelectric conversion photocell. The invention significantly improves the photoelectric conversion efficiency by optimizing the structural design, material selection and preparation process of the photocell, and provides a new solution for the development of photoelectric conversion technology. 2. The present invention adopts a back-illuminated structure, that is, light enters the photovoltaic cell from the back of the substrate, avoiding the shielding of the laser by the metal electrode, thereby improving the duty cycle of the photosensitive surface; at the same time, the P surface on the backlight side can be fully covered by metal to form a good ohmic contact, reducing the internal resistance of the chip and further improving the collection efficiency of the photocurrent; 3. The lighting ditch design in the present invention divides the entire illumination area into multiple fan-shaped areas, and optimizes the light guiding effect to achieve light concentration and uniform distribution. This design not only increases the illumination area, but also improves the photoelectric conversion efficiency. Especially under weak light conditions, the design of the lighting ditch can significantly improve the output performance of the photocell; 4. The present invention uses InP material that matches the InGaAs lattice to prepare the window area, ensuring the efficient transmission and low absorption characteristics of light. At the same time, the material selection and structure of the P area and the N area are optimized, and the undoped In0.53Ga0.47As material is used as the active absorption area to improve the light absorption efficiency. In addition, the design of the lightly doped buffer I area and the heavily doped buffer II area reduces the recombination loss of carriers and further improves the photoelectric conversion efficiency; 5. In terms of electrode preparation and series connection technology, the present invention uses wet etching to separate sub-cells, uses polyimide for insulation protection, and then evaporates metal to achieve series connection between sub-cells, thereby increasing the output voltage of the device. This electrode preparation and series connection technology not only simplifies the process steps, but also improves the stability and reliability of the photovoltaic cell. 6. The present invention solves the problem of low photoelectric conversion efficiency of traditional photovoltaic cells through comprehensive means such as back-illuminated structure, lighting ditch design, material selection and structural optimization. These designs and technological innovations not only improve the absorption and conversion efficiency of light energy, but also enhance the output performance and stability of photovoltaic cells; 7. The back-illuminated structure of the present invention not only avoids the shielding of laser by metal electrodes, improves the duty cycle of the photosensitive surface and the photocurrent collection efficiency, but also makes the layout of the metal electrodes more flexible. Since the metal electrodes no longer shield the laser, the light capture ability of the photocell is significantly improved. At the same time, the back-illuminated structure also helps to reduce the absorption and scattering losses of light in the incident path, further improving the overall performance of the photocell. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below in conjunction with the accompanying drawings and implementation examples: Figure 1 It is a schematic diagram of illumination of the present invention; Figure 2 This is a schematic diagram of the series connection of electrodes of the present invention; Figure 3 is the output power of the photocell under different light intensities of the present invention; Figure 4 The short-circuit current and open-circuit voltage corresponding to different wavelengths of the InGaAsP photocell of the present invention; In the figure: the illuminated sector area 1, the illumination trench 2, the sector area connecting contact 3, the anti-reflection film 4, the window area 5, the P area 6, the N area 7, the lightly doped buffer I area 8, the heavily doped buffer II area 9, the electrode 10, and the polyimide insulating protection layer 11. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments: Example 1 like Figure 1 and Figure 2 As shown, a back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell comprises an illuminated sector-shaped area 1 arranged on a substrate, adopts a back-illuminated structural design, the illuminated sector-shaped area 1 is divided into a plurality of sector-shaped units by an illumination ditch 2, the illuminated sector-shaped area 1 is covered with an anti-reflection film 4, the anti-reflection film 4 is connected to the illuminated sector-shaped area 1 through a plurality of sector-shaped area connection contacts 3, a heavily doped buffer area II 9, a lightly doped buffer area I 8, an N area 7, a P area 6, and a window area 5 are sequentially arranged layer by layer below the substrate, each sector-shaped unit is connected through an electrode 10, and a polyimide insulating protective layer 11 is filled inside the battery to achieve electrical isolation and improve mechanical strength.

[0023] In this embodiment, the lighting trench 2 divides the illuminated sector area 1 into a number of sector units, and optimizes the concentration and uniform distribution of light through geometric design.

[0024] Furthermore, the illuminated sector-shaped area 1 is the photosensitive surface of the chip, and the device adopts a back-illuminated chip structure, and light enters from the back of the substrate.

[0025] Furthermore, the geometric design of the lighting trench 2 includes the depth, width and spacing of the lighting trench 2 .

[0026] Furthermore, the anti-reflection film 4 adopts a multi-layer structure design to enhance the transmission efficiency of light in a wide spectral range and has optical stability. The film thickness and refractive index of the anti-reflection film 4 are optimized.

[0027] Furthermore, the window region 5 is made of InP material that is lattice-matched with InGaAs.

[0028] Furthermore, the P region 6 and the N region 7 are the absorption P region and the N region respectively, and together constitute an active absorption region, using undoped In0.53Ga0.47As material.

[0029] Furthermore, the lightly doped buffer region I 8 is a lightly doped N-type InP layer to achieve doping transition.

[0030] Furthermore, the heavily doped buffer region II 9 is a heavily doped N-type InP layer, which is used to make the lower electrode contact, realize lateral conduction, and serve as the back surface field of the battery to reduce the recombination rate of photogenerated holes.

[0031] Furthermore, the electrode 10 is prepared in the heavily doped buffer II region 9, connected to the window 5 of the fan-shaped unit, providing a conductive channel to collect electrons and transport current.

[0032] Example 2 In another preferred embodiment, based on the above embodiment 1, a method for manufacturing any one of the above back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cells comprises the following steps: Step 1: On a semi-insulating InP substrate, a heavily doped buffer II region 9, a lightly doped buffer I region 8, an N region 7, a P region 6, and a window region 5 are sequentially grown, and an illuminated sector region 1 and an illuminated trench 2 are formed by photolithography and etching processes; Step 2: Covering the illuminated sector area 1 with an anti-reflection film 4; Step 3: Prepare an electrode 10 on the heavily doped buffer II region 9, and achieve physical isolation between unit cells through a wet etching process; Step 4: Apply a polyimide insulating protective layer 11 on the electrode 10 to complete the manufacture of the photovoltaic cell.

[0033] Example 3 In another preferred embodiment, based on the above-mentioned embodiments 1 and 2, the implementation and manufacture of the present invention are described in detail below in conjunction with the accompanying drawings: Back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell structure Figure 1 and Figure 2 As shown, it includes an illuminated fan-shaped area 1, an illumination trench 2, a fan-shaped area connecting contact 3, an anti-reflection film 4, a window area 5, a P area 6, an N area 7, a lightly doped buffer I area 8, a heavily doped buffer II area 9, an electrode 10, and a polyimide insulating protective layer 11.

[0034] The specific implementation process is as follows: S1: The free electron concentration in N region 7 is relatively high, and N region 7 is negatively charged. When the free electron concentration in N region exceeds the equilibrium concentration, these free electrons diffuse from N region 7 to P region 6. At the same time, there are more positive charges (i.e., holes) in P region 6. Since N region 7 loses electrons and diffuses to P region 6, the number of holes in P region will decrease accordingly. Holes also move along the concentration gradient and diffuse from P region 6 to N region 7. The diffused N region 7 loses electrons and gains holes and becomes positively charged, while the P region 6 loses holes and gains electrons and becomes negatively charged. This diffusion process forms an electric field, generates a space charge region, and forms a PN junction between the N region and the P region. The potential difference of the PN junction will further affect the movement of free carriers between N region 7 and P region 6, as well as the recombination process of electrons and holes.

[0035] S2: The light passes through the anti-reflection film 4, which enhances the transmittance of the light. The light does not experience obvious reflection loss, maintains a high brightness and sufficient energy, and illuminates the illuminated sector area 1, so that the illuminated sector area 1 can absorb light energy more effectively and then convert it into electrical energy.

[0036] S3: Light excites the electrons of silicon atoms to produce photogenerated electron-hole pairs. As light continues, more photons are incident on the silicon material, further exciting more electrons and generating many electron-hole pairs. The generated free electrons are attracted by the electric field and move toward the N region 7 of the battery, while the holes move toward the P region 6 of the battery due to the direction of the electric field. This migration process causes the charge inside the battery to separate, causing the electrons and holes to be concentrated at the two ends of the battery respectively. As these charged carriers concentrate, the strength of the internal electric field will be further enhanced, thereby increasing the electromotive force of the battery. The electron and hole pairs will concentrate the charge in the battery at both ends due to the action of the electric field.

[0037] S4: A layer of heavily doped buffer region II 9 is grown on a semi-insulating substrate, the purpose of which is to make a lower electrode contact and realize lateral conduction. Good electrode contact is essential for ensuring the effective collection and extraction of current. The heavily doped buffer region II 9 acts as the back surface field of the battery to reduce the recombination rate of photogenerated holes. Since the combination of electrons and holes will lead to energy loss, the lifetime of photogenerated holes can be effectively prolonged by maintaining the electric field strength in the back area of ​​the battery, thereby improving the photoelectric conversion efficiency. The lightly doped buffer region I 8 realizes the doping transition effect, and the lightly doped buffer region I 8 helps to reduce the diffusion of electrons from the heavily doped area to the absorption area. By providing an intermediate layer, the lightly doped buffer region I 8 can slow down the sudden concentration change of carriers, thereby reducing current leakage and charge recombination. The thickness of the buffer layer is controlled within the minority carrier diffusion length, and the total thickness of the buffer layer is about 1.5μm. During the entire growth process, the thickness of the buffer layer needs to be strictly controlled within the minority carrier diffusion length. Therefore, the total thickness of the buffer layer is controlled at about 1.5μm, which can balance the migration efficiency and recombination rate of photogenerated carriers.

[0038] S5: The InP band gap in window region 5 is relatively wide, usually about 1.34 eV, and it fully transmits light in the 1550 nm band without producing obvious light absorption losses. The band-step barrier of the PP-type heterojunction formed with InGaAs is small, and electrons and holes can be transferred from InP to InGaAs at a lower energy cost, thereby improving the collection efficiency of photogenerated carriers. For P-type InGaAs and InP, when the doping concentration is 1E18 cm-3, the minority carrier diffusion length is about 1.1 μm, and the window layer thickness is controlled within 1 μm.

[0039] S6: Photoelectric conversion efficiency test In order to evaluate the performance of the back-illuminated InGaAsInP photovoltaic cell of the present invention under different light intensities and wavelengths, multiple sets of experimental tests were carried out. The experimental results under different light intensities are as follows: Figure 3 As shown in the figure, as the incident light power increases, the output power of the photocell also increases accordingly, indicating that the photoelectric conversion efficiency of the photocell is proportional to the incident light power; this result verifies the stability and reliability of the back-illuminated InGaAs / InP high-efficiency photoelectric conversion photocell proposed in the present invention under different lighting conditions; the experimental results at different wavelengths are shown in the figure. Figure 4 As shown in the figure, the back-illuminated InGaAsInP photovoltaic cell responds differently to light of different wavelengths, which is related to the band gap energy of the photovoltaic cell material and the wavelength of light; at wavelengths close to the band gap energy of the material, the back-illuminated InGaAsInP photovoltaic cell exhibits a higher photoelectric conversion efficiency; since the incident light of the silicon photovoltaic cell includes visible light and part of the near-infrared light, and the InP material has a wide band gap, the short-circuit current and open-circuit voltage corresponding to different wavelengths of the InGaAsP photovoltaic cell are shown in the figure. Figure 4It can be seen that the photocell fully transmits light in the 1550nm band.

[0040] S7: Material selection and preparation methods: When the transmission distance is more than 1 km or even tens or hundreds of kilometers, medium and long wave lasers should be selected, and correspondingly materials with small bandgap width should be selected to make photoelectric energy cells. Therefore, InAs is selected as the P-level material to reduce losses and ultimately improve conversion efficiency. The lattice of InP matches InAs, so that they can form a high-quality heterojunction, reduce the occurrence of defects and thermally induced dislocations, and improve the efficiency and stability of optoelectronic devices, so InP material is selected as the N-level material.

[0041] To prepare materials such as InGaAs and InP, it is necessary to select high-quality ARS (As) and P (phosphorus) sources and use argon as the carrier gas; through molecular beam epitaxy (MBE) technology, a thin InP buffer layer is first grown on the InP substrate, and then indium and gallium are gradually introduced to grow the InGaAs layer; to prepare single-crystal InP substrates, a (100) orientation is usually selected, with a size of about 2 inches to 4 inches, and the substrate is cleaned to remove oxides and contaminants on the substrate surface. The substrate temperature is set between 500°C and 600°C in a high vacuum environment; the source materials are high-purity indium, gallium, arsenic and phosphorus, which are evaporated from different source materials. The temperature for evaporating indium and gallium is 150~200°C, the temperature for evaporating arsenic source is 500~600°C, and the temperature for evaporating phosphorus source can be 800°C; the InGaAs growth temperature is controlled at 500°C~600°C, maintaining a high vacuum or low-pressure atmosphere, using argon as a carrier gas, and keeping the environment free of oxygen and moisture to prevent the introduction of impurities; after the growth is completed, annealing is performed at a temperature of 400°C to 500°C to improve the crystal quality and electronic properties of the material.

[0042] In the preferred scheme, the illuminated sector-shaped area 1 is the photosensitive surface of the chip, and the device adopts a back-illuminated chip structure, and light enters from the back of the substrate; this design effectively reduces the absorption and scattering losses of light in the incident path, improves the photoelectric conversion efficiency, and the reasonable sector-shaped distribution in the chip structure can effectively even out the distribution of light and further enhance the photoelectric response.

[0043] In the preferred scheme, the lighting ditch 2 divides the illuminated fan-shaped area 1 into a number of fan-shaped units, and optimizes the concentration and uniform distribution of light through geometric design; the above setting enables each fan-shaped unit to obtain appropriate light intensity, avoids the occurrence of blind spots and over-bright areas, achieves concentration and uniform distribution of light, and further enhances the photoelectric response; by optimizing the light guiding effect, light concentration and uniform distribution are achieved, thereby improving the photoelectric conversion efficiency under weak light conditions.

[0044] In the preferred embodiment, the geometric design of the lighting ditch 2 includes the depth, width and spacing of the lighting ditch 2; the above settings, through fine regulation, ensure the reasonable planning of the light path, reduce light loss, and improve the utilization rate of light energy; its geometric design, the depth, width and spacing of the lighting ditch 2 are precisely calculated to ensure the best light capture capability, while effectively reducing the scattering loss of light inside the ditch.

[0045] In the preferred scheme, the design of the fan-shaped area connecting contacts 3 strengthens the electrical connection between the fan-shaped illumination areas, ensuring that the photogenerated carriers can be quickly transmitted to the electrodes, effectively reducing the carrier recombination loss; the optimized contact layout can also reduce the series resistance of the photocell and improve the overall output performance.

[0046] In the preferred embodiment, the anti-reflection film 4 adopts a multi-layer structure design, which enhances the transmission efficiency of light in a wide spectral range and has optical stability. The thickness and refractive index of the anti-reflection film 4 are optimized. The above settings reduce the reflection loss of light at the interface. The multi-layer anti-reflection film 4 structure can significantly enhance the transmission efficiency of light in a wide spectral range and ensure that more light enters the absorption area. In addition, the optimized design of the film thickness and refractive index enables it to have good optical stability.

[0047] In a preferred solution, the window region 5 is made of InP material that is lattice-matched with InGaAs. The above arrangement not only ensures good lattice matching between the window region 5 and the InGaAs layer, reduces interface defects, but also improves the light stability of the device, so that the entire optoelectronic device performs well in high-performance applications. When the doping concentration is 1E18cm -3 The minority carrier diffusion length is about 1.1 μm, so the window layer thickness is controlled within 1 μm to reduce the recombination probability of photogenerated carriers and improve the quantum efficiency.

[0048] In the preferred scheme, the P region 6 and N region 7 are respectively the absorption P region and N region, which together constitute the active absorption region, and use undoped In0.53Ga0.47As material. The optimized active region thickness is 3μm, which is responsible for absorbing light energy and generating photogenerated carriers. When the active region thickness is 3μm, the light entering the active region can be absorbed by nearly 90%, significantly improving the photoelectric conversion efficiency; the above settings can reduce the dark current of the photoelectric device and improve the response speed; at the same time, high aluminum component AlGaAs is used as a blocking layer to effectively limit carrier diffusion and further improve the photoelectric conversion efficiency and stability of the device.

[0049] In a preferred embodiment, the lightly doped buffer region I 8 is a lightly doped N-type InP layer, and an InP semi-insulating substrate is selected to facilitate unit isolation, achieve doping transition, and reduce the diffusion of electrons from the heavily doped InP layer to the absorption region.

[0050] In the preferred embodiment, the heavily doped buffer region II 9 is a heavily doped N-type InP layer, the purpose of which is to make lower electrode contacts, realize lateral conduction, and serve as the back surface field of the battery to reduce the recombination rate of photogenerated holes. The above arrangement improves the photoelectric conversion efficiency of the battery. At the same time, the design of this region also optimizes the electric field distribution, enhances the collection of photogenerated carriers, and further ensures the stable operation of the battery under high light conditions.

[0051] In the preferred embodiment, the electrode 10 is prepared in the heavily doped buffer II region 9, connected to the window 5 of the fan-shaped unit, providing a conductive channel, collecting electrons and transmitting current; the above arrangement enables the electrode 10 to provide a conductive channel, collect electrons and transmit current in the photovoltaic cell; the electrode material is selected from low-resistivity metals, and the thickness design is combined with the conductive requirements of the photovoltaic cell to ensure that it has excellent conductive properties and does not block light from entering the absorption area.

[0052] In the preferred scheme, a semi-insulating material is selected for the substrate, and the electrode 10 is prepared by multiple photolithography processes to achieve the same-side layout of the electrodes; channel isolation is formed between the unit cells by wet etching to the semi-insulating substrate, and then ohmic contact is made by partially etching to the N+ layer; in addition, the setting of the polyimide insulating protection layer 11 provides insulation function and improves the mechanical strength and environmental adaptability of the photocell.

[0053] In summary, the back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell and its manufacturing method proposed in the present invention are intended to solve the long-standing problem of low photoelectric conversion efficiency in the field of photoelectric conversion technology, especially the challenges faced by traditional front-incident structure photovoltaic cells, such as the metal electrode blocking part of the incident light, resulting in a decrease in the duty cycle of the photosensitive surface and unreasonable division of the illumination area. The present invention innovatively adopts a back-illuminated structure to allow light to enter the photovoltaic cell from the back of the substrate. This design not only avoids the shielding of the laser by the metal electrode, significantly improves the duty cycle of the photosensitive surface, but also enhances the photoelectric conversion efficiency. In addition, the photovoltaic cell adopts a fan-shaped distribution structure and an illumination ditch 2 design to scientifically and reasonably divide the illumination area into a number of fan-shaped units, and through the optimization of the geometric design, the concentration and uniform distribution of light are achieved. This structure can greatly improve the photoelectric conversion efficiency under weak light conditions. In terms of material selection, the present invention adopts InGaAsInP as the main material of the photovoltaic cell, and its excellent photoelectric properties provide a solid foundation for achieving efficient photoelectric conversion. At the same time, combined with light The fine structural design of the doped buffer region I 8 and the heavily doped buffer region II 9 further optimizes the photoelectric conversion process and significantly improves the performance of the photovoltaic cell. In particular, the lightly doped buffer region I 8 effectively reduces the reflection loss of light at the interface by constructing a doping gradient transition layer, thereby further improving the photoelectric conversion efficiency. In terms of the design of the electrode 10 and the series-parallel process, the present invention uses a transparent conductive film as the contact layer of the positive electrode, and leads the electrode out through advanced welding technology, while covering it with an anti-reflection film to reduce light loss. In addition, a fine isolation trench is formed on the substrate through a wet etching process, and the series and parallel connection of unit cells is successfully realized, which not only improves the output power and current stability of the photovoltaic cell, but also provides strong support for the flexible configuration and efficient utilization of the photovoltaic cell in practical applications. The comprehensive application of these designs and processes makes the back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell and system proposed in the present invention show significant advantages in terms of photoelectric conversion efficiency, performance stability and application scope, injecting new vitality into the development of photoelectric conversion technology.

Claims

1. Back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell, characterized by: The invention comprises an illuminated sector-shaped region (1) arranged on a substrate, adopting a back-illuminated structural design, wherein the illuminated sector-shaped region (1) is divided into a plurality of sector-shaped units by an illumination ditch (2), the illuminated sector-shaped region (1) is covered with an anti-reflection film (4), the anti-reflection film (4) is connected to the illuminated sector-shaped region (1) through a plurality of sector-shaped region connection contacts (3), a heavily doped buffer region II (9), a lightly doped buffer region I (8), an N region (7), a P region (6), and a window region (5) are arranged layer by layer below the substrate, and the sector-shaped units are connected through electrodes (10), and a polyimide insulating protective layer (11) is filled inside the battery to achieve electrical isolation and improve mechanical strength.

2. The back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell according to claim 1, characterized in that: The lighting ditch (2) divides the illuminated sector-shaped area (1) into a plurality of sector-shaped units, and optimizes the concentration and uniform distribution of light through geometric design.

3. The back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell according to claim 2, characterized in that: The geometric design of the lighting trench (2) includes the depth, width and spacing of the lighting trench (2).

4. The back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell according to claim 3, characterized in that: The anti-reflection film (4) adopts a multi-layer structure design, enhances the transmission efficiency of light in a wide spectral range, and has optical stability. The film thickness and refractive index of the anti-reflection film (4) are optimized.

5. The back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell according to claim 4, characterized in that: The window region (5) is made of InP material that is lattice-matched with InGaAs.

6. The back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell according to claim 5, characterized in that: The P region (6) and the N region (7) are the absorption P region and the N region respectively, and together constitute an active absorption region, using undoped In0.53Ga0.47As material.

7. The back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell according to claim 6, characterized in that: The lightly doped buffer I region (8) is a lightly doped N-type InP layer to achieve doping transition.

8. The back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell according to claim 7, characterized in that: The heavily doped buffer II region (9) is a heavily doped N-type InP layer, which is used to make lower electrode contacts, realize lateral conduction, and serve as the back surface field of the battery to reduce the recombination rate of photogenerated holes.

9. The back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell according to claim 8, characterized in that: The electrode (10) is prepared in the heavily doped buffer II region (9), connected to the window (5) of the fan-shaped unit, and provides a conductive channel to collect electrons and transport current.

10. A method for manufacturing a back-illuminated InGaAs / InP high-efficiency photoelectric conversion photovoltaic cell according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: Step 1: growing a heavily doped buffer II region (9), a lightly doped buffer I region (8), an N region (7), a P region (6), and a window region (5) in sequence on a semi-insulating InP substrate, and forming an illuminated sector region (1) and an illuminated trench (2) by photolithography and etching processes; Step 2: Cover the illuminated sector area (1) with an anti-reflection film (4); Step 3: preparing an electrode (10) on the heavily doped buffer II region (9), and achieving physical isolation between unit cells by a wet etching process; Step 4: Apply a polyimide insulating protective layer (11) on the electrode (10) to complete the manufacture of the photovoltaic cell.

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