The stability of an isolated macrostep under a temperature gradient is
discussed theoretically for the growth of III-V-semiconductors from a
metallic solution, such as liquid phase epitaxy (LPE) and the travell
ing heater method (THM). To find the distribution of solute at the sur
face of one macrostep, the two-dimensional diffusion equation is solve
d, taking into account anisotropic interface kinetics as an important
boundary condition. By analyzing the influence of growth rates and add
itional temperature gradients at the growth face it is found for the b
ehavior of a macrostep, that for decreasing growth rates and for incre
asing temperature gradients the macrostep gets unstable and disappears
. Details about the calculation and a comparison with experimental res
ults from space grown crystals are presented.