Abstract:
Growth of vicinal surfaces is typically affected by two types of structural instabilities: meandering and bunching. Here we address bunching in a simple one-dimensional model. The mechanism drivingthe instability is effectively negative Ehlich-Schwoebel barrier. In the long-time behaviour, the distance betweeen bunches grows as a power with universal exponent close to 0.4 and eventually results in a collapse of all steps into a single bunch, for any negative value of the ES barrier. The shape of the stationary bunch is characterised by a logarithmic singularity. Analytic treatment using a coarse-grained Fokker-Planck equation confirms the observed logarithmic profile.