STEP BUNCHING - GENERALIZED KINETICS

Our previous model of the effect of a parallel shear flow and anisotro pic interface kinetics on the onset of (linear) instability during gro wth from a supersaturated solution is extended to allow for a kinetic coefficient which is a nonlinear function of the supersaturation and c rystallographic orientation. The presence of impurities in the binary solution is also treated, although for typical impurity levels there i s no explicit effect of impurities on morphological stability. As prev iously, a shear flow counter to the step motion enhances stability and a shear flow in the direction of the step motion promotes instability . Instability is enhanced when the kinetic coefficient increases rapid ly with supersaturation. Specific calculations are carried out for par ameters appropriate to the growth of ADP and KDP from solution. (C) 19 98 Elsevier Science B.V. All rights reserved.