NOVEL TUNNELING EXPERIMENTS ON ORGANIC HETEROSTRUCTURES

In analogy to inorganic semiconductor devices tunnel junctions consist ing of organic heterostructures incorporated between two gold electrod es are built. Molecular layers are formed by using Langmuir-Blodgett f ilms of two different molecules, a phthalocyanine- and a perylene-deri vative. Tunnel characteristics at 4.2 K of junctions incorporating two different molecular layers exhibit rectifying behaviour and show equi distant steps in the current, reminiscent of single electron charging phenomena. At higher temperatures the tunneling current is superceded by thermal hopping processes through defect states which over-ride the steplike structure in the curves. The absolute tunneling current thro ugh the junction roughly scales with the active junction area.