Semiconductor light-trapping structure preparation method

Abstract

The application provides a semiconductor light-trapping structure preparation method, which comprises the following steps: forming a first interference light field on a material to be processed by using two lasers, wherein the fringes of the first interference light field are distributed along a first direction, so that a concave structure distributed along the first direction is formed on the surface of the material to be processed; forming a second interference light field on the material to be processed by using two lasers, wherein the fringes of the second interference light field are distributed along a second direction, so that a concave structure distributed along the second direction is formed on the surface of the material to be processed, and the first concave structure and the second concave structure intersect to form a conical structure arrayed on the surface of the material to be processed; and laser induction is performed on the conical structure on the surface of the material to be processed by using a Gaussian light spot, so that a nano-scale structure is formed on the surface of the conical structure. The semiconductor light-trapping structure preparation method provided by the application can efficiently complete the preparation of large-scale light-trapping structures.

Description

Technical Field

[0001] This invention relates to the field of laser processing technology, and in particular to a method for preparing a semiconductor light-trapping structure. Background Technology

[0002] Currently, there are two main approaches to reducing optical losses on the surface of solar cells: one is to utilize antireflective films, and the other is to utilize antireflective light-trapping structures on the solar cell surface. Utilizing antireflective films refers to employing antireflective coatings that exhibit resonant structures within a limited spectral range and specific incident angle, and are effective in this regard. However, these coatings also have some unavoidable drawbacks, such as thermal mismatch, adhesion, and stability. Utilizing antireflective light-trapping structures on the solar cell surface refers to directly fabricating antireflective light-trapping structures on the surface of the solar cell material using various physical and chemical methods. Fabricating light-trapping structures on the surface of solar cell materials can produce structures randomly distributed on the silicon surface with relatively simple processes. Laser-induced fabrication is commonly used for light-trapping structures; however, laser-induced fabrication is limited to small-scale production and cannot yet be applied to large-scale light-trapping structure fabrication. Summary of the Invention

[0003] The semiconductor light-trapping structure fabrication method provided by this invention can efficiently complete the fabrication of large-scale light-trapping structures.

[0004] This invention provides a method for fabricating a semiconductor light-trapping structure, comprising:

[0005] Two laser beams are used to form a first interference light field on the material to be treated. The fringes of the first interference light field are distributed along a first direction, so that a recessed structure distributed along the first direction is formed on the surface of the material to be treated.

[0006] Two laser beams are used to form a second interference light field on the material to be treated. The fringes of the second interference light field are distributed along a second direction, so that the surface of the material to be treated forms a recessed structure distributed along the second direction. The first recessed structure and the second recessed structure intersect to form an array of conical structures on the surface of the material to be treated.

[0007] A Gaussian spot is used to laser-induce the conical structure on the surface of the material to be treated, so that a nanoscale structure is formed on the surface of the conical structure.

[0008] Optionally, the two laser beams are incident at an angle of 0.5-30° on the surface of the material to be treated.

[0009] Optionally, when using a Gaussian spot to laser-induce the conical structure on the surface of the material to be treated, the interval between two adjacent processing paths is 40%-80% of the diameter of the Gaussian spot.

[0010] Optionally, when using a Gaussian spot to laser-induce the conical structure on the surface of the material to be treated, the spot energy density is 1-2 J / cm2 and the scanning speed is 20-70 mm / s.

[0011] Optionally, the diameters of the first and second interference light fields are 5-10 mm, and the interference periods are 300 nm-20 μm.

[0012] Optionally, the angle between the interference fringes of the first interference light field and the second interference light field is 90°.

[0013] Optionally, the diameter of the Gaussian spot is 40-150 μm.

[0014] Optionally, the material to be processed is placed in an air atmosphere.

[0015] Optionally, using two laser beams to form a first interference field or a second interference field on the material to be treated includes:

[0016] A laser beam is split into two laser beams using a beam splitter;

[0017] Two laser beams are irradiated at the same location on the surface of the material to be treated to form a first interference light field or a second interference light field.

[0018] Optionally, when the first interference field, the second interference field, and the Gaussian spot are formed, the laser wavelength used does not exceed 600nm and the output power does not exceed 5W.

[0019] In the technical solution provided by this invention, a large-area cone structure is prepared using a two-stage laser interference method, enabling the efficient and low-cost fabrication of large-scale cone structures. Furthermore, the distribution of the cone structure during laser interference is highly controllable, allowing for control over aspects such as the array's arrangement period, the cone's characteristic dimensions, and its shape. After the laser interference process, a Gaussian spot is applied again, forming a nanoscale three-dimensional structure on the cone's surface, significantly enhancing the semiconductor material's light absorption capacity. Attached Figure Description

[0020] Figure 1 This is a flowchart of a method for fabricating a semiconductor light-trapping structure according to an embodiment of the present invention;

[0021] Figure 2 A scanning electron microscope image of a light-trapping structure prepared by a semiconductor light-trapping structure preparation method according to another embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] This invention provides a method for fabricating a semiconductor light-trapping structure, such as... Figure 1 As shown, it includes:

[0024] Step 100: Two laser beams are used to form a first interference light field on the material to be processed. The fringes of the first interference light field are distributed along a first direction, so that a recessed structure distributed along the first direction is formed on the surface of the material to be processed.

[0025] In some embodiments, when two laser beams interfere, a fringe-like interference light field is formed; that is, higher energy is present at the bright fringes, and lower energy is present at the dark fringes. Simultaneously, using two laser beams for interference allows for the production of extremely small bright and dark fringes, resulting in a dense and fine-grained recessed structure, which is beneficial for improving the absorption of light by the semiconductor material. An etching process is then performed on the material to be processed at the bright fringes of the first interference light field.

[0026] Step 200: Two laser beams are used to form a second interference light field on the material to be processed. The fringes of the second interference light field are distributed along a second direction, so that the surface of the material to be processed forms a recessed structure distributed along the second direction. The first recessed structure and the second recessed structure intersect to form an array of conical structures on the surface of the material to be processed.

[0027] In some embodiments, the fringe direction of the second interference light field should be different from that of the first interference light field, and the fringe directions of the two interference light fields should intersect to form an array of conical structures. Etching will occur at the bright fringes of the second interference light field. The deepest recess is located at the intersection of the bright fringes of the second and first interference light fields. The top of the conical structure is located at the intersection of the dark fringes of the second and first interference light fields. The recess depth at the intersection of the dark fringes of the second and first interference light fields is the same as the depth after the first interference light field processing. Ideally, the recess depth at the intersection of the bright and dark fringes of the second and first interference light fields should be the same as that formed in step 100.

[0028] Step 300: A Gaussian spot is used to laser-induce the conical structure on the surface of the material to be treated, so that a nanoscale structure is formed on the surface of the conical structure.

[0029] In some embodiments, a Gaussian spot is used to laser-induce the material to be treated. In this case, the surface of the conical structure is exposed in the Gaussian spot. After laser induction, a nanoscale microstructure is formed on the surface of the conical structure, which can further enhance the absorption of light by the semiconductor material.

[0030] In the technical solution provided by this invention, a large-area cone structure is prepared using a two-stage laser interference method, which enables the efficient and low-cost fabrication of large-scale cone structures. Furthermore, the distribution of the cone structure is highly controllable during laser interference, allowing for control over aspects such as the array's arrangement period, cone feature size, and cone shape. After the laser interference process, a Gaussian spot is applied again to form a nanoscale three-dimensional structure on the cone structure surface, significantly enhancing the semiconductor material's light absorption capacity.

[0031] As an optional implementation, the two laser beams are incident at an angle of 0.5-30° on the surface of the material to be treated. In some embodiments, adjusting the angle of the two laser beams can change the fringe size of the interference light field, that is, it can change the size and spacing of the conical structure.

[0032] As an optional implementation, when using a Gaussian spot to laser-induce the conical structure on the surface of the material to be treated, the interval between two adjacent processing paths is 40%-80% of the diameter of the Gaussian spot. In some embodiments, since the energy is higher at the center of the Gaussian spot and lower at the edge, in this embodiment, the interval between two adjacent processing paths is set to a portion of the diameter of the Gaussian spot, so that all conical structures can be processed with higher energy, forming a more uniform and better nanoscale structure.

[0033] As an optional implementation, when using a Gaussian spot to laser-induce the conical structure on the surface of the material to be treated, the spot energy density is 1-2 J / cm2 and the scanning speed is 20-70 mm / s.

[0034] As an optional implementation, the diameters of the first and second interference light fields are 5-10 mm, and the interference periods are 300 nm-20 μm.

[0035] As an optional implementation, the angle between the interference fringes of the first interference light field and the second interference light field is 90°. In some embodiments, when the angle between the interference fringes of the two interference light fields is 90 degrees, the arrangement of the conical structure can be more regular, and the shape of the conical structure can also be more regular. At the same time, it is also more beneficial for determining the direction when laser-induced by the Gaussian spot.

[0036] As an optional implementation, the diameter of the Gaussian spot is 40-150 μm.

[0037] As an optional implementation, the material to be processed is placed in an air atmosphere. In some embodiments, the etching process using an interference light field is a process of forming a conical structure, during which impurities inevitably accumulate. A Gaussian spot is used for laser induction, during which some of the accumulated impurities are removed, and some are reconstituted with the conical structure to form the microstructure of the conical surface. Because the accumulated impurities are removed or utilized during laser induction, processing can be achieved in an air atmosphere without the need for a special protective atmosphere, reducing processing costs.

[0038] As an optional implementation, using two laser beams to form a first interference field or a second interference field on the material to be processed includes:

[0039] A laser beam is split into two laser beams using a beam splitter;

[0040] Two laser beams are irradiated at the same location on the surface of the material to be treated to form a first interference light field or a second interference light field.

[0041] In some embodiments, light interference is sensitive to frequency, vibration direction and phase. In this embodiment, the method of splitting the same laser beam into two beams can more smoothly complete the interference of the two laser beams.

[0042] As an optional implementation, when the first interference light field, the second interference light field and the Gaussian spot are formed, the laser wavelength used does not exceed 600nm and the output power does not exceed 5W.

[0043] The technical solution of the present invention will be described in detail below with reference to an exemplary embodiment:

[0044] This embodiment provides a method for fabricating a semiconductor light-trapping structure. An ultrafast laser with a wavelength of 515 nm and a pulse width of 600 fs is used to process a silicon wafer region. The laser incident angle is 2.3°, the diameter of the interference light field distribution is 10 mm, and the interference period is 5 μm; a nanostructure depth of 267 nm is formed. Subsequently, a laser-induced circular Gaussian spot with a diameter of 100 μm is used, with a row spacing of 50 μm, a spot energy density of 1.2 J / cm², and a scanning speed of 30 mm / s. After processing, the morphology of the light-trapping structure is observed using a scanning electron microscope, such as... Figure 2 As shown in the magnified image, nanoscale structures can be seen growing on the pointed, micron-sized structure.

[0045] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for fabricating a semiconductor light-trapping structure, characterized in that, include: Two laser beams are used to form a first interference light field on the material to be treated. The fringes of the first interference light field are distributed along a first direction, so that a recessed structure distributed along the first direction is formed on the surface of the material to be treated. Two laser beams are used to form a second interference light field on the material to be treated. The fringes of the second interference light field are distributed along a second direction, so that the surface of the material to be treated forms a recessed structure distributed along the second direction. The recessed structure distributed along the first direction and the recessed structure distributed along the second direction intersect to form an array of conical structures on the surface of the material to be treated. A Gaussian spot is used to laser-induce the conical structure on the surface of the material to be treated, so that a nanoscale structure is formed on the surface of the conical structure. The two laser beams are incident at an angle of 0.5-30° on the surface of the material to be treated. When using a Gaussian spot to laser-induce the conical structure on the surface of the material to be processed, the interval between two adjacent processing paths is 40%-80% of the diameter of the Gaussian spot.

2. The method according to claim 1, characterized in that, When using a Gaussian spot to laser-induce the conical structure on the surface of the material to be treated, the spot energy density is 1-2 J / cm². 2 The scanning speed is 20-70 mm / s.

3. The method according to claim 1, characterized in that, The diameters of the first and second interference light fields are 5-10 mm, and the interference periods are 300 nm-20 µm.

4. The method according to claim 1, characterized in that, The angle between the interference fringes of the first interference light field and the second interference light field is 90°.

5. The method according to claim 1, characterized in that, The diameter of the Gaussian spot is 40-150µm.

6. The method according to claim 1, characterized in that, The material to be processed is placed in an air atmosphere.

7. The method according to claim 1, characterized in that, Using two laser beams to form a first or second interference field on the material to be processed includes: A laser beam is split into two laser beams using a beam splitter; Two laser beams are irradiated at the same location on the surface of the material to be treated to form either the first interference light field or the second interference light field.

8. The method according to claim 1, characterized in that, When the first interference light field, the second interference light field, and the Gaussian spot are formed, the laser wavelength used does not exceed 600nm and the output power does not exceed 5W.

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