Photoconductive imaging in a photon scanning tunnelling microscope capableof point-contact current sensing using a conductive fibre probe

A photoconductive photon scanning tunnelling microscope was developed to in vestigate the point-contact photoconductive properties of condensed matter. In order to detect the current and the optical signal at a local point on a surface, we coated the edge of a bent type fibre probe with indium tin ox ide. Thus it was possible to measure both photocurrent and optical property with subwavelength resolution. The performance of the novel microscope was evaluated by analysing an organic thin film of copper phthalocyanine (CuPc ), which is known to be an efficient photoconductive material. Photocurrent and current-voltage characteristics were observed at the local point on th e CuPc thin films. Furthermore, photoconductive images were obtained with t opography and near-field optical imaging using this system. The photoconduc tive PSTM shows potential in various areas of future optics and electronics .