Monte Carlo simulations were used to study the effect of an electric field upon the surface diffusion of adatoms during the measurement of scanning tunnelling microscopy tunnelling-current fluctuations. It was found that the correlation function of the tunnelling-current fluctuations was proportional to the adatom density fluctuation. The diffusion coefficients were inversely proportional to the time constant of the correlation function. The form of the correlation, and the measured time constant, were calculated as a function of the ratio of the temperature to the strength of the electric field. It was noted that the effect of the field was more pronounced when the measurement was carried out in the early non-equilibrium regime in which the adatom density evolved towards its equilibrium distribution under the spatially dependent electrostatic potential that was due to the electric field.

Effect of a STM Tip on the Surface-Diffusion Measurement: a Monte Carlo Study X.Wang, Q.Li, M.C.Tringides: Physical Review B, 1998, 57[12], 7275-80