Suppression of nucleation during crystallization of amorphous thin Si films

Abstract

The ability to selectively suppress crystal nucleation during the crystallization of amorphous Si films is often desirable, but is not generally possible. We demonstrate that a periodic two-step process−involving intermediate temperature ion irradiation followed by high-temperature isothermal annealing−can suppress nucleation in amorphous regions without destroying existing crystals or inhibiting crystal growth. When interpreted in the context of transient nucleation theory, our results indicate that the size distribution of critical and subcritical-sized clusters is modified by exposure to intermediate temperature high-energy ion irradiation. The reduction in the population of critical-sized clusters, which presumably occurs via an interfacial amorphization process, in turn leads to a prolonged incubation period in the subsequent thermal annealing step during which nucleation is negligible but crystal growth is substantial.