Explosive crystallization of amorphous materials is a fascinating phenomenon that has attracted much attention from engineers, physicists, materials scientists and others for over two decades. It manifests itself as a thermally activated, highly exothermic phase transition of a solid material from a metastable amorphous state to a stable crystalline state, that occurs in the form of a self-propagating crystallization front. The front propagation can be triggered by a local heat rise produced mechanically, or by a laser beam. The laser-beam-triggered explosive crystallization of amorphous semiconductor films is a widely used modern technology for producing silicon-on-insulator structures that have many applications in various photovoltaic devices like solar cells or infrared detectors, low-cost, low-power consuming at panel displays, etc.
The objective of the proposed project is to initiate and develop a fruitful collaboration between the theoretical group at Northwestern and the experimental group at Berkeley, to carry out systematic theoretical and experimental investigations of several important aspects of explosive crystallization that have not been previously studied. The collaboration will focus on mathematical modeling and experimental studies of nonlinear dynamics of instabilities exhibited by explosive crystallization fronts and the resulting microstructures. Specifically, we propose to investigate the stability and nonlinear dynamics of explosive crystallization fronts in several different modes of frontal propagation, as well as explosive crystallization in alloys and the effect of dopants on the crystallization dynamics. From the fundamental point of view, the significance of the proposed research is in elucidating such important effects as the instabilities and nonlinear dynamics of explosive crystallization fronts in several modes that provide examples of complex nonlinear behavior in systems far from thermodynamic equilibrium. From the technological point of view, the results will enhance our understanding of the modern technological process of explosive crystallization in thin amorphous films. The established collaboration will allow us to move further in our future joint research to more detailed investigations of microstructure in explosively crystallizing materials which is a necessary prerequisite to control and optimization of the process. The broader impact of the proposed research lies in its interdisciplinary nature, its importance for both scientists and engineers. It will also create a sound basis for training graduate students in future stages of the collaborative research that will provide them with the unique opportunity to participate in important research at the cutting edge of engineering, applied physics and applied mathematics, combining both theoretical and experimental components.
This research has been funded jointly by the Division of Mathematical Sciences in the Mathematics and Physical Sciences Directorate and the Division of Chemical and Transport Systems in the Engineering Directorate. Funding is from the Mathematical Sciences: Innovations at the Interface with the Sciences and Engineering Program, Announcement NSF 04-538.
