Crystalline silicon nanoparticles as carriers for the Extended Red Emission

In an attempt to determine the carrier of the Extended Red Emission (ERE), we have investigated a series of amorphous and crystalline materials: natural coal, amorphous hydrogenated carbon, amorphous hydrogenated silicon carbide, porous silicon, and crystalline silicon nanoparticles. The photoluminescence (PL) behavior of various samples of these materials upon excitation with UV light was studied at room temperature focusing on both the wavelength dependence of the photoluminescence and the PL yield. For some samples the yield is by far too low, other samples do not comply with the characteristic wavelength range of ERE. Only the samples of nanocrystalline silicon (porous silicon and silicon nanoparticles) reveal PL properties that are compatible with the astronomical observations. Besides this experimental evidence, we will supply additional arguments leading to the conclusion that silicon nanoparticles should be seriously considered as an attractive carrier for the Extended Red Emission.