Theory of dipole generation at cleaved semiconductor surfaces

We have computed the dipole moments for a range of Si clusters cleaved along both glide and shuffle (111) planes. The moments arise due to the breaking of inversion symmetry by the crack. The values are somewhat sensitive to the cluster size, but there appears to be a clear indication that the dipole moments from glide plane cleavage are some two orders of magnitude greater than for shuffle plane cleavage. This provides a difference between the two kinds of cleavage that may be useful for determining which occurs, and hence decide on surface models.