Anti-reflection In2O3 nanocones for silicon solar cells

In2O3 nanocones were synthesized on silicon substrates using thermal evaporation of In2O3 precursor powder followed by annealing in oxygen ambient. The morphology and aspect ratio of the nanocones strongly depend on the thermal budget during processing. The grown structures had tapered morphology as observed from microscopic analysis. The layers showed a minimum reflectance of ∼3% over a wide range of spectrum from 300 nm to 1100 nm with a high transmittance of ∼90%. The material has an energy band gap of 3.93 eV. X-ray diffraction analysis revealed that the annealed layers were crystallized in (2 2 2) plane. Moreover, these layers showed photoluminescence at 464 nm, 481 nm, 487 nm and 558 nm under the excitation wavelength of 325 nm. This frequency (photon) shifting towards more favourable wavelength regime is expected to improve the blue response of the solar cell device.