Effect of surface acoustic waves on single electron tunneling in scanning tunneling microscopes

We study the effect of surface acoustic waves (SAWs) on single electron tunneling (SET) in scanning tunneling microscopes (STMs). SAWs periodically change the distance between STM tips and substrates. Since tunneling rates have an exponential dependence on the tunneling distance, SAWs strongly affect tunneling phenomena, especially SET oscillations, We numerically study the regularity of the SET oscillations through distributions of tunneling events under both current and voltage biases. It is found that the degree of the regularity is associated with the localization of the phase difference between SAW and SET at tunneling.