Steady-state structures in composition-modulated alloys: kinetic phase transition between 1D and 2D patterns

摘要

A non-linear continuum theory of self-organized growth of composition-modulated structures in alloys is developed. It is shown that, for a lattice-matched alloy, where compositional and morphological instabilities are uncoupled in the linear regime, the two instabilities are coupled due to non-linear effects. Due to non-linear coupling, composition-induced stresses may lead to an instability of the advancing surface against undulations. A non-planar surface profile favors kinetic phase transition from the growth of a 1D modulated structure to the growth of a 2D one. A steady state phase diagram in variables "temperature—growth velocity" is constructed which contains regions of homogeneous alloy growth, of 1D steady state structures, of 2D steady state structures, and the region where both 1D and 2D structures are possible. For zinc blend semiconductors, the interplay between the anisotropic elasticity and anisotropic surface diffusion may lead to the kinetic phase transition between the growth of a 2D structure modulated in the elastically soft directions [100] and [010] to the growth of a 1D structure modulated in the direction of the fast diffusion [110]. Our theory explains this type of transition observed in the growth of InAlAs/InP.