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: natur al coal, amorphous hydrogenated carbon, amorphous hydrogenated silicon carb ide, porous silicon, and crystalline silicon nanoparticles. The photolumine scence (PL) behavior of various samples of these materials upon excitation with UV light was studied at room temperature focusing on both the waveleng th dependence of the photoluminescence and the PL yield. For some samples t he yield is by far too low, other samples do not comply with the characteri stic wavelength range of ERE. Only the samples of nanocrystalline silicon ( porous silicon and silicon nanoparticles) reveal PL properties that are com patible with the astronomical observations. Besides this experimental evide nce, we will supply additional arguments leading to the conclusion that sil icon nanoparticles should be seriously considered as an attractive carrier for the Extended Red Emission.