Step bunching: generalized kinetics

Our previous model of the effect of a parallel shear flow and anisotropic interface kinetics on the onset of (linear) instability during growth from a supersaturated solution is extended to allow for a kinetic coefficient which is a nonlinear function of the supersaturation and crystallographic orientation. The presence of impurities in the binary solution is also treated, although for typical impurity levels there is no explicit effect of impurities on morphological stability. As previously, 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 rapidly with supersaturation. Specific calculations are carried out for parameters appropriate to the growth of ADP and KDP from solution. (C) 1998 Elsevier Science B.V. All rights reserved.