ADATOM DIFFUSION CHARACTERISTICS FROM STM NOISE - THEORY

Adatoms moving along the substrate surface under an STM tip cause a random time dependence of the current, J(t). We have obtained simple expressions for the average current [J(t)] and the temporary current correlation function [J(t + tau)J(tau)]tau - [J(t)]2 through the diffusion coefficients of the adatoms and a few parameters of the tunneling gap. The results offer a way to study the local diffusion of adatoms by treatment of experimentally measured J(t) dependencies.