Enhancing light trapping efficiency: Germanium-coated porous silicon structures for optimal antireflection performance

Porous silicon structures are effective in trapping light due to the abundance of pores on their surface, finding widespread use in optical applications like photoelectric conversion, photon collection, and detection. We have successfully created micro-porous silicon with exceptionally high antireflection performance through electrochemical etching using different concentrations of silver catalysts. Results show that this germanium coated porous silicon structure has a smaller range of pore sizes, leading to a reduced reflectivity of 2.6 % under light radiation with wavelengths. To understand the antireflective mechanism further, we explored the surface reflectivity of porous silicon structures by coating the germanium metal on the porous structure. Importantly, germanium coated porous silicon structures with high surface quality and well-preserved pore integrity are identified as beneficial for achieving lower reflectivity in the incident light wavelength range of 300-1200 nm. These findings are significant for the design of porous silicon antireflective materials.