Photoluminescence from stain-etched polycrystalline Si thin films

Visible room-temperature photoluminescence (PL) has been observed from stain-etched polycrystalline Si thin films. Poly-Si thin films deposited on oxidized Si and quartz substrates became porous (PoSi) after stain-etching in a 1:3:5 solution of HF:HNO3:H2O. Under UV excitation, the stain-etched doped and undoped poly-Si films produce uniform orange-red (∼650 nm) luminescence very similar to that obtained from stain-etched crystalline Si substrates. Stained amorphous thin films did not exhibit photoluminescence. Luminescent patterns with sub-micrometer (∼0.6 μm) dimensions have been obtained for the first time from PoSi produced from poly-Si films.