Research connects the porous structure of silicon and its ability to 'trap' incident light

https://phys.org/news/2022-04-porous-silicon-ability-incident.html

"used the finite time domain difference method (FDTD) to calculate and compare surface reflectivity of porous silicon structures with different pore sizes... porous silicon structure when prepared under optimal corrosion parameters can achieve an average reflectivity as low as 2.3 percent for light in incident wavelength range of 300 to1000 nm... pore sizes of 300 to 700 nm could achieve lower reflectivity,... points the way for design and preparation of future low-reflectivity porous silicon structures"