Nanometer-Scale Photoelectric Property of Organic Thin Films Investigated by a Photoconductive Atomic Force Microscope

A photoconductive atomic force microscope (AFM), which is a contact mode current-sensing AFM combined with an optical pumping laser, was developed in order to investigate the interaction between light and matter in a nanometer-scale tinny structure. The principle of the photoconductive AFM is the measurement of the photocurrent in an individual nanometer-scale structure, and also two-dimensional mapping of the photoelectric property by scanning the conductive cantilever on the surface of a sample. The photoelectric property of an organic thin film with copper phthalocyanine was demonstrated to test the performance of this system. Nanometer-scale point contact photocurrent, point contact current–voltage characteristics and photoconductive imaging could be attained using the system. Photoconductive AFM has the potential to be of use in various fields of nanometer-scale photonics.