Defect studies in as-deposited and processed nanocrystallineSi/SiO2structures

Nanocrystalline silicon ${\mathrm{}(\mathrm{n}\mathrm{c}-\mathrm{S}\mathrm{i})/\mathrm{S}\mathrm{i}\mathrm{O}}_2$ samples formed by varying processing conditions have been examined using electron spin resonance (ESR) and photoluminescence. Results indicate the presence of three ESR centers associated with the oxidized and annealed samples, one of which has been identified as an $E^{\prime }$ defect (O vacancy), a second as an oxygen thermal donor which is most important at low temperatures, and a third as a Si dangling-bond resonance which is more pronounced at higher temperatures. The thermal donor line shows a strong correlation with the 1.5 eV emission exhibited by the oxidized and annealed nc-Si samples. It is suggested that an oxide-related defect similar to that reported in oxidized porous silicon may be the source of this optical emission.