Dynamic force microscopy and Kelvin probe force microscopy of KBr film on InSb(0 0 1) surface at submonolayer coverage

Dynamic force microscopy (DFM) and Kelvin probe force microscopy (KPFM) have been used to study epitaxial growth of KBr film at submonolayer coverage on InSb(0 0 1) surface in UHV. It has been found that the shape of initially formed deposit islands of monatomic-thick reflects the anisotropy of the substrate surface. The work function of KBr film covered InSb(0 0 1) is lower by about 210 meV than the work function of the clean InSb(0 0 1) substrate. It has been demonstrated that such differences allow for application of Kelvin probe force microscopy as a tool for detecting the chemical contrast on surfaces with high resolution. Moreover, it is shown that KPFM technique, despite its inherent limitation of spatial resolution is capable of imaging variations of the electrostatic potential associated with monatomic steps.