Size dependence of Pb-type photoluminescence quenching defects at the Si nanocrystal interface
Department of Physics, and INPAC-Institute for Nanoscale Physics and Chemistry, University of Leuven Celestijnenlaan 200D, B-3001 Leuven, Belgium, EU
2 IMTEK, Faculty of Engineering, Albert-Ludwigs-University Freiburg - Georges-Köhler-Allee 103, D-79110 Freiburg, Germany, EU
Accepted: 29 August 2011
Size-controlled Si nanocrystals (nc's) of ∼ 2 to 5 nm diameter embedded in amorphous (a-)SiO2 are extensively studied by electron spin resonance (ESR) and photoluminescence (PL). The PL quenching Pb-type (Si dangling bond) interface defects ––Pb(0) and Pb1 centers–– are investigated as a function of Si nc's size and effective interface area with the embedding SiO2. It is shown that the effective areal Pb-type defect density at the nc-Si/SiO2 interface remains approximately constant, indifferent of the nc size. While Si nc's larger than ≈3.5 nm are found to house, on average, at least one PL quenching Pb-type defect, about 75% of the as-annealed 2 nm Si nc's appear Pb-free. Additional study on the effect of heat treatment in H2 indicates this step to be more efficient in inactivating Pb(0) than Pb1 for all Si nc sizes.
PACS: 78.67.BF – Nanocrystals, nanoparticles, and nanoclusters / 61.72.Hh – Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.) / 68.35.Dv – Composition, segregation; defects and impurities
© EPLA, 2011