Pulsed laser deposition of Si nanodots for photonic applications

Several growths of Si nanodots on Si and GaAs substrates were conducted by pulsed laser deposition (PLD) using a KrF laser of 248nm, 15ns, 12Hz and a Ti-sapphire laser of 800nm, 130fs, 1kHz at 1x10-5mbar vacuum. The laser fluencies on a Si target were varied from 3 to 32J/cm(2) for the nanosecond (ns) PLD growths and 1-2.75J/cm(2) for the femtosecond (fs) PLD. Wide range of nanodots from 20nm to a few micron size droplets were observed from both the ns and fs PLD. Auger electron spectroscopy of the nanodots was conducted and which indicated that the nanodots were without contamination. A technique using a mask consisting of an array of small holes was used to obtain high density nanodots with uniform size. The array of 100nm diameter holes was created by E-beam lithography. With this technique we have achieved 100nm Si dots with 300nm spacing between them, with few defects. We have observed that laser fluences closer to the ablation threshold work better for deposition using the EBL mask. In summary, we have demonstrated the growth of 100nm Si nanodots in an array with very few defects using the EBL masking technique.