Formation of Si nanoclusters in amorphous silicon thin films by excimer laser annealing

It is shown that an Si nanocluster is formed in an amorphous silicon (a-Si) thin film following irradiation using a pulsed KrF excimer laser. The photoluminescence spectrum of the irradiated 70 nm thick a-Si film at a power density of 180 mJ/cm2 at one shot shows two luminescence bands centred at approx. 1.31 and 1.76eV. The peak emission wavelength depends on the silicon nanocluster size, which is approx. 3-4 nm. A mechanism for the formation of Si nanoclusters is also proposed.