The study of defect removal etching of black silicon for solar cells

To enhance the absorption of incident light of solar cells, multicrystalline black silicon has been successfully fabricated by plasma immersion ion implantation using SF6 and O2. After that a defect removal etching (DRE) process under different conditions has been performed to slow down the surface recombination by decreasing surface area and plasma etching damage. The surface microstructures, reflectance and internal quantum efficiency have been investigated by a field emission scanning electron microscope, a spectrophotometer and a quantum efficiency measurement system, respectively. It is found that the height and density of nanohills on the surface of black silicon decreases with increase in time of DRE, and the surface reflectance decreases with increase in height and density of nanohills. The internal quantum efficiency(IQE) of solar cells with a DRE process shows a large improvement than that without a DRE process, so as the performance of conversion efficiency. The best performance of the solar cells with a DRE process shows the conversion efficiency, open circuit voltage and short circuit current density as high as 17.46%, 623 mV and 35.99 mA/cm2, showing an improvement of conversion efficiency of 0.72% than that of conventional acid textured cells.