Optical Spectra of Residual Porous Silicon

The spectra of absorption (μ), reflection (R), ε2, and E2ε2 of residual silicon (r-Si) were calculated using the R spectra of porous silicon in the range from 0 to 20 eV and with ε2(E) in the range 2.5–5.0 eV of porous silicon specimens with P = 0.57, 0.66, and 0.77. The ε2 spectra of r-Si were decomposed into elemental components. We calculated their main parameters: the energies of maxima Ei and halfwidths Hi of bands, their areas Si, and heights Ii, and oscillator strengths fi. The two-phase Bruggeman model of effective dielectric function and Kramers–Kronig analysis were applied in the calculations. The essential differences between the optical spectra of the residual and cubic silicon were established. They are at least partially attributed to the quantum dimensional effects. The data obtained are compared with the known theoretical spectra of silicon clusters.