Nano Express

Nanoscale Research Letters

, Volume 3, Issue 9, pp 315-320

Open Access This content is freely available online to anyone, anywhere at any time.

Surface-Related States in Oxidized Silicon Nanocrystals Enhance Carrier Relaxation and Inhibit Auger Recombination

  • Andreas OthonosAffiliated withDepartment of Physics, Research Center of Ultrafast Science, University of Cyprus Email author 
  • , Emmanouil LioudakisAffiliated withDepartment of Physics, Research Center of Ultrafast Science, University of Cyprus
  • , A. G. NassiopoulouAffiliated withIMEL/NCSR Demokritos, Terma Patriarchou Grigoriou

Abstract

We have studied ultrafast carrier dynamics in oxidized silicon nanocrystals (NCs) and the role that surface-related states play in the various relaxation mechanisms over a broad range of photon excitation energy corresponding to energy levels below and above the direct bandgap of the formed NCs. Transient photoinduced absorption techniques have been employed to investigate the effects of surface-related states on the relaxation dynamics of photogenerated carriers in 2.8 nm oxidized silicon NCs. Independent of the excitation photon energy, non-degenerate measurements reveal several distinct relaxation regions corresponding to relaxation of photoexcited carriers from the initial excited states, the lowest indirect states and the surface-related states. Furthermore, degenerate and non-degenerate measurements at difference excitation fluences reveal a linear dependence of the maximum of the photoinduced absorption (PA) signal and an identical decay, suggesting that Auger recombination does not play a significant role in these nanostructures even for fluence generating up to 20 carriers/NC.

Keywords

Silicon nanocrystals Carrier dynamics Ultrafast spectroscopy Surface-related states Auger recombination