Observation of non-radiative de-excitation processes in silicon nanocrystals



We describe the impact of non-radiative de-excitation mechanisms on the optical emission from silicon nanocrystals formed in SiO2. Auger excitation via free carriers deliberately introduced through phosphorus ion implantation, shows a monotonic increase with increasing phosphorus concentration which can be modelled adequately using a simple statistical approach. We also report a reduction in nanocrystal luminescence intensity with increasing exposure to UV radiation and suggest this phenomenon results from the introduction of non-radiative defects in the Si/SiO2 network. The effect of UV radiation varies significantly depending on the sample preparation. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)