Phenomenological Theory of Explosive Solid Phase Crystallization of Amorphous Silicon. II. Dynamical Processes

Abstract

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.

Influence of heat conducting substrates on explosive crystallization in thin layers

“…However, only the non-dimensional activation energy of diffusion appears in the first-order results of the asymptotic analysis, whereas the contribution of the activation energy of nuclei turned out to be negligible. Thus, the present results are also valid if the growth velocity is simply modelled with an exponential function of the Arrhenius type, as it is often done [22,23,[26][27][28][29][30][31][32][33][34].…”

“…The result shows that the heat loss from the layer due to the presence of the substrate depends on the history of the process. This is in contrast to descriptions with an apparent heat transfer coefficient [22][23][24][25].…”

“…The rate equation was derived previously [4] from a theory of non-isothermal crystallization that accounts for all essential physical phenomena [13][14][15][16]. The use of semi-empirical laws as in [21][22][23][24], for instance, is thereby avoided. The heat diffusion equation is solved by applying Duhamel's integral.…”

Explosive crystallization of amorphous silicon films by flash lamp annealing

“…There have been a number of experimental reports concerning the EC using several types of pulse light sources such as Q-switched ruby lasers, [12][13][14][15][16][17][18] XeF excimer lasers, 19 frequency doubled or tripled Nd:YAG ͑yttrium aluminum garnet͒ lasers, [20][21][22][23] Nd-glass lasers, 24 and continuous-wave ͑cw͒ Ar ion lasers with scanning, [25][26][27] as well as many theoretical investigations. [28][29][30][31][32] Characteristic periodic surface structures with approximately 1 m pitch spacing have been observed in the poly-Si films formed by FLA, 8,9,33 which may be an indication of the onset of the EC triggered by FLA because similar structures have been observed in the materials crystallized through EC. 18,23 In this study, we have investigated the surface appearances and the microstructures of the poly-Si films in order to clarify the crystallization mechanism of a-Si films by FLA.…”

Crystallization waves in thin amorphous layers on heat conducting substrates

“…As the propagation speed in metals, and other materials of practical importance, is rather large, the process is often called "explosive crystallization".A literature survey shows that the quantitative prediction of explosive crystallization is commonly based on semi-empirical laws, e.g. by assuming a temperature dependent propagation speed of the crystallization front, or by introducing an apparent heat transfer coefficient to describe the heat loss to the substrate [1][2][3][4][5].In the present work, the process of self-sustaining explosive crystallization is analysed on the basis of first principles. Fig.…”