Crystallization Kinetics of Hydrogenated Amorphous Silicon During Pulsed Excimer Laser Annealing

ABSTRACTExplosive crystallization of amorphous silicon (a-Si) during pulsed laser annealing occurs at an intermediate laser energy fluence above the threshold for surface melting. Mediated by a molten silicon layer which is undercooled with respect to crystalline silicon and above the melting point of a-Si, the crystallization interface drives down into the sample, sustaining itself due to the difference in the latent heats of the crystalline and amorphous silicon. Explosive crystallization has been the subject of numerous studies which have for the most part been restricted to ion implanted amorphized layers in silicon bulk samples. In this study we examine the crystallization kinetics of vapor deposited thin films of hydrogenated a-Si for films of differing hydrogen content and substrate temperature. We reevaluate current models of interface and nucleation kinetics qualitatively in light of these results. The fundamental physical mechanisms in these non-equilibrium phase transitions during pulsed laser annealing are discussed.