Effect of Annealing Time on the Growth, Structure, and Luminescence of Nitride-Passivated Silicon Nanoclusters

Rapid thermal annealing has been used to study the changes in luminescence and structure from silicon-rich silicon nitride films for annealing times ranging from 2 seconds to 1 hour at 600 and 800°C. Silicon nanoclusters formed within the silicon nitride host matrix provided the source of the luminescence in the films through quantum confinement effects. Room temperature photoluminescence spectra exhibited a large, abrupt red-shift in emission after only 2 seconds of annealing, indicating early formation and growth of the silicon nanoclusters occurs through a fast transient diffusion mechanism. This initial shift was followed by a slower but steady growth of the nanoclusters as the annealing time was increased further. X-ray absorption near edge structure at the Si K- and L3,2-edges supported the trends observed in the photoluminescence spectra, providing evidence of silicon nanocluster growth and restructuring of the silicon nitride host matrix over the course of annealing.