Atomic force microscopy images of porous silicon samples prepared with different conditions have been correlated with photoluminescence (PL) and Raman spectra, allowing a clear classification of two types of samples, ‘‘gently’’ etched versus ‘‘heavily’’ etched. The gently etched samples show a significantly improved morphology and uniformity, as well as consistent correlation in PL and Raman results with the quantum confinement model for the light emission.