Spectral and dynamical study of nonlinear luminescence from silicon nanocrystals excited by ultrashort pulses

✍ Scribed by K. Žídek; F. Trojánek; B. Dzurňák; P. Malý; I. Pelant

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 255 KB
• Volume: 41
• Category: Article
• ISSN: 1386-9477
• DOI: 10.1016/j.physe.2008.08.004

✦ Synopsis

We report on the spectral and dynamical properties of photoluminescence (PL) under ultrashort (femtosecond and picosecond) laser pulse excitation in Si nanocrystals prepared by Si + -ion implantation into a silica matrix. We concentrate on the luminescence properties that make it possible to distinguish several luminescence bands within a broad luminescence spectrum. In time-integrated luminescence, saturation-related changes suggest a presence of two different recombination channels connected to the nanocrystal volume states and the nanocrystal-SiO 2 interface. The saturation of the luminescence can be explained in terms of Auger recombination. We investigated in detail fast sub-nanosecond luminescence, where significant differences were observed under UV excitation (linear pump-intensity dependence, PL maximum at 450 nm) and for the excitation wavelengths in the visible part of the spectrum (superlinear pump-intensity dependence, broad luminescence band including wavelengths as short as 300 nm). We propose a rate-equations model based on the Auger and radiative/nonradiative recombination to interpret the experimental data.