Femtosecond luminescence spectroscopy of core states in silicon nanocrystals

• Published in: Optics express Vol. 18; no. 24; pp. 25241 - 25249
• Main Authors: Žídek, K, Trojánek, F, Malý, P, Ondič, L, Pelant, I, Dohnalová, K, Šiller, L, Little, R, Horrocks, B R
• Format: Journal Article
• Language: English
• Published: United States 22-11-2010
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.18.025241

We present a study of ultrafast carrier transfer from highly luminescent states inside the core of silicon nanocrystal (due to quasidirect transitions) to states on the nanocrystal-matrix interface. This transfer leads to a sub-picosecond luminescence decay, which is followed by a slower decay component induced by carrier relaxation to lower interface states. We investigate the luminescence dynamics for two different surface passivation types and we propose a general model describing spectral dependence of ultrafast carrier dynamics. Our results stress the crucial role of the energy distribution of the interface states on surface-related quenching of quasidirect luminescence in silicon nanocrystals. We discuss how to avoid this quenching in order to bring the attractive properties of the quasidirect recombination closer to exploitation.