Fabrication of surface textures by ion implantation for antireflection of silicon crystals

We report on a method based on ion implantation and thermal annealing to fabricate silicon surface textures for antireflection purposes. Modification to crystalline Si surfaces by hydrogen ion implantation is a well known phenomenon, but the surface structures generated by H implantation alone, typically of a low packing density and small aspect ratio, are not effective in suppressing light reflection from Si. We show that coimplantation of hydrogen and argon, combined with thermal annealing and oxidation, can result in an interesting surface morphology in Si crystals, yielding the lowest light reflectance of ∼1% over a broad spectral range at various light incident angles. In addition, lattice damage to crystalline Si generated by ion implantation is reduced or completely removed by the annealing processes. Possible mechanisms for the formation of such observed surface textures are discussed.