The Effect Of Hydrogen Passivation On Photoluminescent Properties Of Nc-Si/SiO₂ Superlattice

There is an urgent requirement for an optical emiter that is compatible with standard silicon-based ultra-large-scale integration (ULSI) technology. Bulk silicon has an indirect energy bandage and is therefore highly inefficient as a light source, necessitating the use of other materials for this purpose. So the study on luminescent nanocrystalline Silicon has become the hot point and forehead at the field of agglomeration physics and microelectronics. The most attention has been paid to embedding Si nanocrystals film, mostly because of its high external quantum efficiency of light emission originated from quantum confinement of carriers in silicon crystals of nanometer size.SiO/SiO₂ superlattices samples were prepared on Si substrates by reactive evaporation of SiO powder in vacuum or an oxygen atmosphere. The samples were annealed in nitrogen atmosphere at high temperature subsequently. And then, these samples with formed Si nanocrystals were implanted with H⁺ to dose of 3.0×10¹⁴/cm² and 3.0×10¹⁵/cm² respectively at 20Kev. The PL spectra showed that the PL intensities of Si nanocrystals as-implanted dropped sharply compared with those without H⁺ implanting. The PL intensity increased gradually with the increasing re-annealing temperature; and it even could exceed that of Si nanocrystals without H⁺ implanting if the dose of H⁺ was enough. Our further investigations showed that the varieties of the PL intensities were mainly dependent on the area density of the defects on the surface of Si nanocrystals, and also the area density of the defects were influenced by the dose of H⁺ and further re-annealing temperatures.Basing on analysis of the effect of hydrogen passivation on photoluminescene of the defects in SiO₂, we found that photoluminescene of the defects in SiO2 was greatly ruleless with variety of re-annealing temperatures after ions implanting. It contributed by breakage and recombination on the defects within SiO₂ after H⁺ implanting and re-annealing, perhaps. However with increasing of the re-annealing temperature the PL intensities of nc-Si were more sensitive than those of the structure defects in the samples.