Si texturing with sub-wavelength structures

Si surface reflection has been investigated with textured structures smaller than the optical wavelengths. This physical optics approach relies on absorption through a wave-guide mechanism, and has been realized for both uniform and random structures. Laser interferometric techniques have been lithography combined with conventional wet and reactive ion etching of Si to form a wide range of nanoscale 1-D & 2-D structures in both single & poly-crystalline Si substrates. Maskless reactive ion etching of Si has also been employed to form highly absorptive nanoscale structures. For identically etched structures, uniform structures showed an order of magnitude smaller reflectance than random structures.