We have prepared free-standing porous silicon (FPS) samples with various
porosities using electrochemical etching. The result of a study combining
absorption and photoluminescence (PL) from FPS samples with porosities in
the range 53–76% is presented. A blue shift of the PL peak position and
an increase of the PL intensity with enhancing porosity have been observed.
Furthermore, the PL peak and intensity of porous silicon (PS) samples are
compared with FPS samples. Our results show that the PL peak intensity
reduces 1.5–2.5 times from PS to FPS. However, no notable shift of the PL
peak position from PS to FPS has been observed.