IN QUEST OF UNRESTRICTED GROWTH OF BULK CRYSTALS BY LIQUID-PHASE ELECTROEPITAXY

The two different modes of bulk crystal growth by liquid phase electro epitaxy: (i) constant electric current density, and (ii) constant crys tal growth velocity, have been analyzed by employing one dimensional m ass transport model. In a constant current density mode, the growth ve locity as a function of time is found to be of the form: V(t)= V-0 exp (t/t(0)), with a characteristic time constant, t(0), entirely defined by the initial growth conditions. The t(0) parameter can be varied fro m a few days to a few hours, depending on the intensity of convection in the melt and the initial current density. For an extended period of the growth time, while growing bulk crystals by liquid phase electroe pitaxy (LPEE), exponentially increasing growth velocity may result in deteriorated growth interface stability and dendrites, in accordance w ith experimental data. When the growth velocity is expected to remain constant, while growing compositionally uniform bulk crystals by LPEE, the current density should be varied with time in the following manne r: J = J(0)(1 + t/t(0)) In this growth mode, the Joule heat produced i n a growing crystal is gradually decaying with time, thus, bulk crysta ls of virtually unlimited thickness are feasible by LPEE. The above mo del is particularly suitable in optimizing the LPEE growth parameters when rotation of the substrate and/or source material is employed.