Luminescent nanoclusters array fabricated by pulsed laser beam irradiation

Ordered luminescent nanoclusters array in the form of grating structures are fabricated on silicon (1 0 0) surface by Q-switched Nd:YAG laser beam irradiation of second harmonic wavelength (532 nm) in vacuum. Blue-green photoluminescence (PL) spectrum from the ordered nanoclusters array exhibits two asymmetrical peaks at 2.58 eV and 2.88 eV in the blue-green region corresponding to the bimodal distribution of nano size clusters. The size of the nanoclusters is estimated from the three dimensional quantum-confined model incorporating Gaussian size distribution. When subjected to rapid thermal annealing at 710 °C for 10 min in N₂ atmosphere there is an enhancement of the PL intensity without any change in the peak emission energy and broadening suggesting that the origin of PL is related to quantum confinement effect in Si nanocrystallite. The surface morphology of the irradiated surface varies considerable with the number of laser shots, laser fluence and ambient conditions.