Surface Potential Measurements of Organic Thin-Film Transistors by Kelvin-Probe Force Microscopy

Abstract

2017, Accepted August 23, 2017 ) Kelvin-probe force microscopy ( KPFM ) is a surface potential mapping technique based on dynamic-mode atomic force microscopy ( AFM ) . It is useful to visualize carrier injection barriers and trapped charges in operating organic thin-ˆlm transistors ( OTFTs ) . Since it is desirable to perform KPFM experiments in vacuum conditions, frequency modulation ( FM ) technique is often used to oper-ate AFM / KPFM. We review two operating modes of KPFM using FM-AFM in vacuum and demonstrate visualization of the carrier injection barriers and trapped charges in OTFTs. We also introduce a method to visualize the transient distribution of the trapped charges being evacuated from