Measurement of porous silicon dielectric constant by VUV laser harmonic radiation

By combining the use of laser harmonic radiation as vacuum ultraviolet (VUV ) light source with that of a standard NIR-VIS-UV spectrometer, the reflect ance of porous silicon over a wide en ergy spectral range from 1 to 16 eV w as measured. Reflected intensity modulation due to interference effects ari sing from the finite thickness of the porous layer in the visible range was also taken into account and reduced by fringe fitting. Porous silicon diel ectric constant was then deduced from reflectance measurements by Kramers-K ronig analysis. Data are found to be in good agreement with those reported in literature, thus showing that laser harmonics represent a new alternativ e and suitable VUV source for optical characterisation of materials.