Visualization of Charge Injection Processes in Polydiacetylene Thin Film Grains by Dual-Probe Atomic Force Microscopy

Abstract

We have recently developed a dual-probe atomic force microscopy (DP-AFM) system having two AFM cantilever probes whose positions can be independently controlled with a precision on the order of ten nanometers. In this study, we visualized charge injection processes in polydiacetylene thin film grains using the DP-AFM system. One of the two probes was used to apply bias voltages to the grains while the other probe was used to obtain surface potential images of the grains. The surface potential of the polymerized grain changed according to the applied bias voltages. The potential profiles at the edge of the grain were not sharp when negative voltages were applied to the grain, which suggests the existence of an electron injection barrier at the interface. Moreover, it is suggested from the same experiment conducted in vacuum that the p-type semiconductor characteristics of the polydiacetylene is due to the O2 hole doping.