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

Abstract

We report the laser annealing effects on the structures and properties of silicon nanocrystal films fabricated by pulsed-laser deposition in inert argon gas. The surface morphology of the as-deposited films is greatly determined by the angle relative to the laser ablation spot. Photoluminescence (PL) peaked at 620 nm corresponding to 2.0 eV is observed in the as-deposited films. After single-pulse laser annealing, better crystallinity and increased PL intensity are obtained. The PL peak remains at 620 nm. High laser fluence causes damage to the films and the threshold fluence for laser ablation is around 100 mJ/cm2. Multiple-pulse laser annealing with increasing pulse number at fluences below the threshold of laser ablation can provide better crystallization and property improvement than single-pulse annealing. There are a certain number of pulses for the best multiple-pulse annealing effect before damage or laser ablation occur.