Laser annealing of silicon nanocrystal films prepared by pulsed-laser deposition

Abstract

We studied the laser annealing effects on the structures and properties of silicon (Si) nanocrystal films fabricated by pulsed-laser deposition in inert argon gas. The as-deposited samples show large particles (i.e., droplets) with size ranging from ∼100 nm to several μm on a uniform background film. The strong photoluminescence (PL) was from the background film rather than from the crystalline droplets. The consistency of the PL and crystal size from the background film supports the quantum confinement effect theory. After KrF excimer laser annealing, nanoparticles (NPs) with sizes of 10–50 nm were formed in the as-deposited films. In the vicinity of the droplets, the NPs were aligned together to form incident-light-angle-dependent cylindrical ripples which were caused by the interference of the incident light and the surface-scattered waves. The threshold fluence of surface melting was also reduced due to the interference. The intensity enhancement and blueshift of PL, the correlation between the indirect transition in optical absorption, and the bonding information in infrared spectra, further reveal the oxidation and ablation during the laser annealing process.