Correlation of Raman and photoluminescence spectra of porous silicon

The discovery of luminescence in electrochemically etched porous silicon is an extremely important scientific breakthrough with enormous technological implications. It opens the door for silicon, the most important microelectronic material, as a possible material for optoelectronics applications. Our result, a correlation of Raman and photoluminescence spectra, shows that the observed luminescence is originated from extremely small microstructures. As the luminescent peak increases in photon energy, the Raman feature shifts to lower energy, remaining sharp, and eventually splits, developing into TO and LO modes. No peak at 480 cm−1 is observed, which indicates no substantial contribution from an amorphous region. These data provide strong evidence of the role of microstructures in porous silicon.