Metal-Assisted Chemical Etching of Mesoporous Silicon - Optical Properties

In this research, a mesoporous silicon sample is fabricated by noble metal-assisted chemical etching that p-type silicon is used. The characteristics and morphology of the sample is examined by EDX and FESEM. The optical properties are investigated by PL, UV, Raman and FTIR spectroscopy. The purity of silicon is determined using EDX analysis. The size of pores is examined by FESEM and found to be in the range of 19 to 67 nm. PL in both pure and mesoporous silicon shows a peak at 727 nm wavelength equal 1.7 eV energy. UV reflectance and absorbance have a peak at 381 nm in mesoporous and 369 nm in pure silicon. PL and UV analysis are used to estimate the value of energy band for mesoporous silicon which was found to be 1.7 eV. Raman analysis is performed on pure and mesoporous silicon samples and the results of this experiment show a peak for both samples of silicon at the same wavelength of 519 cm-1, but revealed a higher intensity for mesoporous silicon than that of pure silicon. FTIR results indicate an absence of bonding between the silicon surface and the noble metal in mesoporous silicon, all observed peaks are attributed to the bonding between silicon and elements present in the surrounding air. The optical analysis together with the value of the energy band gap obtained for mesoporous silicon indicate that it could potentially be a suitable candidate for solar cells.