Processes in phase boundary region during liquid phase growth

Abstract

Key words liquid phase growth, phase boundary region.The behavior of components within the phase boundary region during liquid phase growth is the subject of the present article. Based on the supposition that the phase boundary is a structured region, repeating the periodicity of the substrate, the distribution of different components within the phase boundary is considered. Assuming that the value of the supersaturation at the upper end of the phase boundary defines the growth rate of the compound, a relation has been derived, concerning the extension of the phase boundary. The case of liquid phase epitaxial growth of GaAs is considered and an effort for evaluation of the phase boundary extension is undertaken. The linear dependence of the stationary growth rate on the cooling rate, predicted previously, is proved experimentally.

Theory and experiments of liquid phase epitaxial growth Part 1

“…The present paper is in fact a continuation of references [32,33]. Two kinds of components have been distinguished: the i-components and the j-components [32][33][34][35][36][37][38]. The i-components are the dilute components of the process -their concentration in the liquid phase is smaller than that in the solid phase:…”

“…The consequence of this fact is that their concentration decreases with time permanently, dC L i /dt < 0, and the liquid phase becomes increasingly deficient in these components [32][33][34][35][36][37][38]. The j-components have a high content in the liquid phase: their concentration in the liquid phase is higher than that in the solid one: C L j > C S j and therefore it increases with time permanently dC L j /dt > 0, the liquid phase becomes more and more abundant of j-components.…”

“…The mass transport of i-components occurs always toward the crystal surface but for the j-components it is in the opposite direction. That is the reason why the liquid phase is supersaturated with respect to the i-components and superheated with respect to the j-components [32][33][34][35][36][37][38].…”

“…The LPE growth is a strongly correlated process -the deposition of the components onto the crystal surface occurs in proportions, subjected to the stoichiometry of the grown compound [32][33][34][35][36][37]. This requirement is always fulfilled and does not depend on the crystallization mechanism, on the intensity of the diffusion mass transport or the process growth regime, i.e.…”

“…During this period the deviation from the stationary conditions is very strong and the growth rate v gr is much larger than the stationary growth rate v * gr . The stationary growth conditions are observed at greater durations of the process [32,33] and the value of the growth rate v * gr is determined by the intensity of the diffusion mass transport -the growth is dominated by the diffusion.…”