Estimation of tunneling-barrier width in scanning tunneling microscope from noise characteristics

A method is proposed for estimation of the potential-barrier width of the tunneling junction of a scanning tunneling microscope (STM). The method is based on measurement of the fluctuations of the tunneling-barrier height and their correlation with the flicker noise of the tunneling current. Measurements with the STM feedback enabled and disabled are considered. Experimental results are presented for a tunneling junction formed by a platinum-iridium tip and a graphite specimen. The principal sources of experimental error are examined.