Origin of Blue Photoluminescence from Naturally Oxidized Porous Silicon

Abstract

Upon the 325 nm excitation from a helium-cadmium laser, the photoluminescence (PL) from aged porous silicon was investigated with fluorescence spectroscopy. Each PL spectrum of the aged porous silicon films contained two luminescent bands, one of the luminescent bands peaked at about 466.7 nm whereas the other luminescent band peaked at about 596.1 nm. The origin of the blue PL from aged porous silicon was discussed, and our results indicated that the blue photoluminescence of porous silicon films originated from the silicon oxide itself.

Anodization Current Density Independent Photoluminescence of Porous Silicon

“…Etch rate increases with current density, since a higher current density provides an increase in the number of charge carriers, and thereby the rate of charge exchange across the interface. The mechanisms on the PL of PS films are still in debate [3][4][5][6][7][8][9][10]. It is safe to conclude at this stage that the PL spectrum of the anodized PS films is independent on the anodization current density for our p-type silicon.…”

“…Fig. 5 has shown that both the silicon nanocrystals (JCPDS file #27-1402) and the silicon dioxide nanocrystals (JCPDS file #38-0360) are present in the PS film [9]. The results in Fig.…”

“…5 indicate that oxidation happens to the silicon nanocrystals because of their large surface area exposed to air. Our previous work has demonstrated that silicon dioxide can give off blue PL under the photo excitation at 325 nm [9]. The orange-red PL of the anodized PS cannot be attributed to the silicon dioxide layer that covers the silicon nanocrystals.…”