Abstract: The conductivity of a wide range of carbon-containing materials is substantially increased by irradiation with particles having an atomic mass of at least 1. Both polymeric and nonpolymeric, organic and inorganic, materials can be used. The particulate irradiation, for example an ion beam, substantially breaks down the material to a form that includes amorphous carbon having unusually high conductivity. Resistivities of less than 10.sup.-3 ohm-cm are possible. When applied as a film on a substrate, the irradiated material can be used for device interconnects. Conducting lines can be produced in the film, as well as vertical contacts through the film.