A novel approach to fabricate a PPy/p-type Si heterojunction

In this paper, we report an innovative method to generate a polypyrrole (PPy)/p-type Si junction. This method includes three fabrication steps. First, a PPy thin film is coated on a polymethylmethacrylate (PMMA) sheet. Second, a microstructure-formed p-type Si mold is inserted into the PMMA sheet. Finally, after separation of the mold and the substrate, the part of the PPy right underneath convex mold structures is removed from the PMMA sheet and attached to the convex mold structures, which form a PPy–Si junction. This junction has demonstrated diode-like characteristics. Compared with existing lithographic approaches, the developed method is simple and does not involve aggressive chemistry in patterning conducting polymers. Although this approach was employed here to particularly generate a PPy–Si junction, it can also be potentially applied to fabricate many other types of conducting polymer based devices, like light emitting diodes, light sensing arrays, transistors, and capacitors.