Optical characterization of porous silicon by synchrotron radiation reflectance spectra analyses

The electronic structure of porous Si(PS) has been characterized by optical reflectance spectra analyses. The reflectance spectra of PS were measured in the photon energy range of 2–27 eV using a synchrotron radiation source. The reflectance at the low energy region was calibrated by the corresponding absolute value which was separately determined from spectroscopic ellipsometry. The spectral response of optical constants were calculated by the Kramers–Kronig analysis. Our results indicate that PS retains some of the characteristic optical features of crystalline Si, and that a blue shift in the absorption edge occurs in PS.