Tip-induced band bending and its effect on local barrier height measurement studied by light-modulated scanning tunneling spectroscopy

Abstract

Local barrier height (LBH) of Si(001) surface was studied using light-modulated scanning tunneling spectroscopy (LM-STS), which enables the observation of the tip-sample-dependent LBH with or without photoillumination simultaneously. The bias voltage and tip-sample distance dependence of LBH were comprehensively understood by the tip-induced band bending (TIBB), which influences the scanning tunneling microscopy and spectroscopy (STM/STS) in measurement of the local electronic structures of semiconductors. A marked decrease in surface photovoltage caused by photocarrier tunneling at shorter tip-sample distance was also shown. On the basis of these results, a method to measure LBH free of TIBB is discussed. [DOI: 10.1380/ejssnt.2006.192]