Laser polycrystalline silicon surface texturing is the process of using a continuous or pulsed laser to ablate the surface of silicon wafers through the photothermal or photochemical effect (under short wavelengths) to remove material. In this process, the outcome of the texturing varies depending on the processing environment. Based on the characteristics of the laser used, laser texturing technology can be broadly divided into the following categories.
Vindiunas uses direct laser ablation technology, as shown in Figure 2, to texturize the surface of
polycrystalline silicon solar cells. Direct laser ablation technology is the most commonly used laser processing method. It relies on a tightly focused laser beam to locally ablate the material and uses a mobile platform or galvanometer scanning to directly texturize the entire surface of the sample. The texturing effect is not influenced by external environmental factors, only by the laser’s processing parameters.

Figure 2 The direct Laser ablation technology
In addition to the aforementioned single laser direct texturing method, some scholars have considered environmental factors and developed laser composite texturing methods for various environments. In the multi-environment composite texturing method, different environments can have varying effects on the texturing outcome. Xu and others found that during the laser texturing process, adding a specific gas to the surface of the silicon-based material can significantly improve the etching effect. They used a nanosecond infrared laser to irradiate silicon wafers and studied the effect of auxiliary gases on the microstructure morphology with different types of gases (SF6, N2). The laser beam is focused by a mirror and then processes the workpiece surrounded by the auxiliary gas, which provides a schematic of laser ablation technology assisted by environmental gases, as shown in Figure 3a. The experimental results show that the type of auxiliary gas significantly influences the microstructure morphology of the material surface. As shown in Figure 3b, the surface roughness of the material microstructure prepared in SF6 gas is greater than that prepared in N2 gas; however, the number and density of the surface microstructures are higher in the material prepared with SF6 gas. The reason is that at room temperature, SF6 gas does not react with silicon-based materials. However, during laser etching, which generates instantaneous high temperatures, SF6 gas corrodes the surface of silicon-based materials (reacting when temperatures exceed 1000°C), thereby assisting in laser texturing.
Figure 3 (a) Processing diagram of Laser ablation assisted by ambient gas
(b) Microstructure formed by SF6 background
Esther and others studied the effect of annealing an a-Si amorphous silicon film and then recrystallizing it to form p-Si using different beam profiles of a second harmonic pulse Ndlaser in an underwater environment. The experimental results show that the roughness of the specimen processed in air is higher, while the processing effect is improved underwater.
In addition to using auxiliary gas (liquid) and ring competition, some scholars have also explored the possibility and effects of combining laser processing with other methods. As shown in Figure 4, Chen and others studied the effects of different water jet injection angles and speeds on the depth and width of laser-etched grooves. The results show that the depth and width of the laser-etched grooves gradually increase with increasing water jet speed. At the same speed, using injection angles that increase the impact force of the water jet results in slightly larger groove depth and width.
Figure 4 Water jet assisted laser technology
Hua Zhang and others used a laser electrochemical composite method to texture the surface of polycrystalline silicon solar cells. The principle, shown in Figure 5, involves using a laser to texture the surface of polycrystalline silicon wafers while simultaneously using an electrolyte to electrochemically corrode the surface for improved texturing. The results show that, within an electrochemical processing voltage range of 10–15 V, the textured surface produced by the laser electrochemical composite method with 30 mJ laser pulse energy can reduce overall reflectivity to less than 10%. Hua Zhang and others also analyzed the differences between the surfaces produced by single laser texturing and laser electrochemical composite texturing by comparing their surface morphology. The results show that, under the same laser pulse energy, using the laser electrochemical composite method subjects the multicrystalline silicon wafer to both laser processing and anode electrochemical dissolution. This combination effectively removes the cladding layer and damaged layer during texturing, resulting in micro-pits with generally larger entrance apertures compared to those processed by single laser texturing.

Figure 5 The laser electrochemical composite velvet processing area of polycrystalline silicon solar cells
In summary, the common laser texturing process involves using a laser as the primary method to texture the surface of polycrystalline silicon wafers. While the methods may vary, the goal of each texturing technique is to create various types of more uniform and dense microstructures on the surface of polycrystalline silicon wafers.