Kelvin Probe Force Microscopy of Semiconductors

Abstract

Due to their technological importance, III–V compound semiconductors have been widely studied. While extensive work has been done on their geometric and electronic structure, Kelvin probe force microscopy (KPFM) in ultrahigh vacuum (UHV) creates the possibility to study the electronic structure of the surfaces on a nanometer scale [1]. The work function is one of the most important values characterizing the property of a surface. Chemical and physical phenomena taking place at the surface are strongly affected by the work function. In turn, the work function variation reflects physical and chemical changes of surface conditions [2]. For example, due to a localized dipole at atomic steps, the averaged work function on a metal surface decreases in proportion to the step density [3]. If molecules or atoms are adsorbed on a surface, the work function changes depending on the magnitude of the electric dipole formed by the adsorbates [2]. Although the work function is defined as a macroscopic concept, it is necessary to consider its microscopic local variations in understanding the details of the formation of semiconductor interfaces and device behavior.