Two-dimensional spectral distribution of photoluminescence from porous silicon

The two-dimensional spectral distribution of photoluminescence (PL) was analyzed for p-type and n-type porous silicon (PS) prepared under different illumination conditions. In the p-type PS fabricated under strong illumination, the peak position of PL distribution in the depth direction moves inside the PS as the wavelength becomes longer. On the other hand, the PS prepared in the dark has an intensity peak of longer wavelength near surface. In the n-type PS formed under illumination, PL intensity has a peak near the PS surface and the peak position of the PL intensity does not move much. The difference between p-type and n-type PS suggests that the penetration depth of the light becomes greater as the PS layer grows and thus the effect of illumination may extend far inside p-type PS.