Temperature-dependent photoluminescence of silicon nanocrystallites prepared by inert-gas-ambient pulsed laser ablation

摘要

The inert-gas-ambient pulsed laser ablation technique is a promising method for preparing Si nanocrystallites. We measured the temperature dependence of photoluminescence (PL) spectra to investigate radiative and nonradiative recombination processes in the nanocrystallites prepared using this method. The Si nanocrystllites showed visible PL bands in the red (1.6 eV) and green (2.1 eV) spectral regions. The intensities of the red and green PL increased with decreasing temperature and then saturated below 80 K. This temperature dependence was compared with that of other photoluminescent Si materials. It was shown that the PL quantum efficiency of the Si nanocrystallites was larger than that of a-Si:H at high temperatures. One of the reasons for the difference in the temeprature dependence between the Si nanocrystallite and a-Si:H is the change in the role of defects in the nonradiative recombination process.