In this paper, we investigate the antiband instability on vicinal Si(111) surfaces with different angles of misorientation. It is known that prolonged direct current–annealing of Si(111) results in the formation of antibands; i.e., the step bunches with the opposite slope to the primary bunches. We provide a theoretical description of antiband formation via the evolution of the atomic steps' shape. We also derive a criterion for the onset of the antiband instability under the conditions of sublimation controlled by slow adatom surface diffusion. We examine this criterion experimentally by studying the initial stage of the antiband formation at a constant temperature of 1270 °C while systematically varying the applied electromigration field. The experiment strongly supports the validity of the derived theoretical criterion and indicates the importance of accounting for the factor of critical field in the theoretical modeling of step bunching or antiband instabilities. Deduced from the comparison of theory and experiment, the Si surface atoms' effective charge cannot exceed double the elementary charge, set by the lower limit of kinetic characteristic length $d_s=0.3$ nm. Using $d_s=1.7-4.5$ nm draws values of the effective charge in line with the values reported in earlier studies.

• Received 17 June 2012

DOI:https://doi.org/10.1103/PhysRevB.86.195317