Saturation of Photoluminescence Intensity from Si Nanocrystals Exposed to Atomic Hydrogen

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Saturation of Photoluminescence Intensity from Si Nanocrystals Exposed to Atomic Hydrogen Hyun-Ji Cho and Jong-Hwan Yoon Department of Physics, College of Natural Sciences, Kangwon National University, Chuncheon 200-701 R. G. Elliman and A. R. Wilkinson Department of Electronic Materials Engineering, Research School of Physical Sciences and Engineering, The Australian National University, Canberra, ACT 0200, Australia (Received 22 July 2008) Si nanocrystals embedded in silicon dioxide lms are exposed to an atomic hydrogen plasma at di erent temperatures in the range from 100 C to 350 C. The photoluminescence (PL) from the nanocrystals is shown to increase in intensity with increasing exposure time before saturating at a level that depends on the exposure temperature. The saturation level depends on the nal exposure temperature and shows no dependence on the thermal history of exposure. This behavior is shown to be consistent with a model in which the steady-state passivation level is determined by a balance between defect passivation and depassivation by hydrogen. Modelling suggests that the di erence in activation energies for the passivation and depassivation reactions is 0.2 eV, with the activation energy for the passivation reaction being larger than that for the depassivation reaction. PACS numbers: 81.65.Rv, 78.67.Bf, 78.55.Ap, 61.72.Cc