High-quality spatially-resolved measurements of electric fields are critical to understanding charge injection, charge transport, and charge trapping in semiconducting materials. Here, we report a variation of frequency-modulated Kelvin probe force microscopy (FM-KPFM) that enables spatially-resolved measurements of the electric field. We measure electric field components along multiple directions simultaneously by employing position modulation and lock-in detection in addition to numeric differentiation of the surface potential. We demonstrate the technique by recording linescans of the in-plane electric field vector in the vicinity of a patch of trapped charge in a DPh-BTBT organic field-effect transistor. This technique is simple to implement and should be especially useful for studying electric fields in spatially inhomogeneous samples like organic transistors and photovoltaic blends.
@article{arxiv.1710.06927,
title = {Vector Electric Field Measurement via Position-Modulated Kelvin Probe Force Microscopy},
author = {Ryan P. Dwyer and Louisa M. Smieska and Ali Moeed Tirmzi and John A. Marohn},
journal= {arXiv preprint arXiv:1710.06927},
year = {2017}
}