Thermal evolution of H-related defects in H implanted Si: from nano-platelets to micro-cracks

Annealing at moderate temperatures (300-450°C) of H implanted silicon leads to the formation of nano-platelets within minutes and of micro-cracks or blisters within hours. Up to now, the mechanism by which they transform from one to another type of H
₂
filled defect was unknown. We have analyzed the evolution of the characteristics of platelets populations at the onset of micro-cracks formation and found it occurs when and where a group of "large" platelets of 50 nm in diameter are close enough, typically at about 50 nm from each other. In situ TEM confirms that sudden nucleation of micro-cracks in place of groups of platelets occurs. It is concluded that micro-crack nucleation results from elastic interactions between neighboring platelets, favoring the opening of the silicon crystal between them.