A survey of the possible autocatalytic crystallization processes called explosive crystallization in liquid and solid states is given. The explosive liquid-phase epitaxy with laterally moving coupled interfaces of melting and crystallization in amorphous silicon layers on insulators is investigated by the use of an experimental equipment consisting of three synchronized lasers supplying the temperature pulses for ignition, spreading, and stopping of the explosive front. The velocity of this explosive crystallization front measured by use of time-resolved reflectivity of a test beam is compared with the results of model calculations. The results are in good agreement. The crystal structure was investigated by optical and transmission electron micrography and represents crystalline laminae grown preferentially in the 〈110〉 direction over a distance of about 100 μm. Areas of some millimeters in diameter can be crystallized by this method.

No abstract

Considering the crystallization in amorphous semiconducting material as a phase transition of first kind a model of a lateral spreading out crystallization process is developed, which takes into account the feed back of the released latent heat to the kinetics of nucleation and growth of crystallites. Deciding between solid and liquid phase crystallization a classification of explosive crystallization phenomena will be given. Model calculations are carried out for lateral moving explosive fronts of solid‐phase epitaxy and solid‐phase nucleation. From the dependence of the velocity of the front on the substrate temperature derived in the case of stationarity it becomes evident, that the explosive solid‐phase epitaxy should be impossible in silicon and the explosive solid‐phase nucleation can initiate explosive liquid‐phase processes.

The autocatalytic or “explosive” solid‐phase crystallization is due to the feed back of the liberated latent heat to the kinetics of the phase transition. The dynamics of the explosive solid‐phase nucleation (ESPN) is studied by use of a model containing phenomenologically the coupling between matter and energy transport in crystallizing amorphous layers of silicon on insulators. The effect of lateral moving explosive crystallization fronts (wave front solution) discussed in part I of this paper is investigated by solving the coupled reaction‐diffusion equations numerically. The evolution of the wave fronts (ignition and dying out) is discussed in dependence on the conditions of the initial temperature distribution, the heat losses and the competitive nucleation processes in the layer. Optimum conditions of ignition and spreading are found.

No abstract