Carbon films with relatively high conductivity

The pyrolysis of organic dianhydrides (e.g., 3,4,9,10‐perylenetetracarboxylic dianhydride) in an evacuated system results in the loss of hydrogen, CO, and CO2 and the deposition of a chemically inert, metallic‐appearing mirrolike film. The films are highly conducting (σRT250 Ω−1 cm−1) and can evidence either metallic or semiconducting behavior, depending on the preparation temperature. Superconducting films are obtained when niobium is used as a dopant. Preparation of films on doped silicon semiconductor chips results in the formation of p‐n junctions. ESR spectra exhibit a moderately strong line at g=2.0025. The resonance intensity remains almost constant to 20 °K, characteristic of a highly delocalized spin system.