Lateral Averaging Effects on Surface Potential Measurements on InAs Dots Studied by Kelvin Probe Force Microscopy

Abstract

Surface potential measurements on InAs quantum dots (QDs) were performed using Kelvin probe force microscopy (KFM) based on noncontact-mode atomic force microscopy. By the KFM measurements, the potential distribution well corresponding to the topography was successfully observed, and the observed potential difference between the InAs QD region and the surrounding wetting layer region was nearly proportional to the QD diameter. From two-dimensional simulations, in which we calculated the appropriate tip bias to minimize the electrostatic force working between the tip and the sample, we considered that the real dependence of the potential on the QD size still existed, although lateral averaging effects on the potential measurements should be considered to explain the potential observed by the actual KFM measurements. We also pointed out that a lateral averaging effect made the observed potential contrast indistinct, particularly when the size of the nanostructure was smaller than the tip radius.