Effects of annealing on luminescence properties of Si nanocrystallites prepared by pulsed laser ablation in inert gas

We prepared Si nanocrystallites by pulsed laser ablation in He gas. The photoluminescence (PL) intensity of nanocrystallites increased after annealing by about one order of magnitude. PL spectra depend on annealing process and excitation photon energy. We observed a broad peak around 2 eV in the PL spectra of the as-deposited sample when excited at 2.5 eV. The full width at half-maximum (FWHM) of the PL peak increased with annealing due to an increase in the broad 1.7 eV component. The PL spectrum when excited at 3.8 eV is composed of peaks at 1.7, 2.0 and 3.0 eV. Although the 1.7 eV component was found with both 2.5 and 3.8 eV excitation, the origins of PL differ for these excitations. The electroluminescence (EL) spectra had a peak at 1.7 eV. The peak energy and shape of the EL is similar to the broad 1.7 eV component of the PL when excited at 2.5 eV.