Electrical characteristics of nitrogen-doped ultrananocrystalline diamond/hydrogenated amorphous carbon composite films prepared by coaxial arc plasma deposition

Nitrogen-incorporated ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films were synthesized in nitrogen and hydrogen mixed gas atmospheres by coaxial arc plasma deposition. The temperature dependence of electrical resistivity implies that carriers are transported in hopping conduction. Heterojunctions comprising 3 at.% nitrogen-doped films and p-Si substrates exhibited a typical rectifying action. The expansion of a depletion region into the film side was confirmed from the capacitance-voltage characteristics, and the built-in potential and carrier concentration were estimated to be 0.51 eV and 7.5 ×10¹⁶cm^-3, respectively. It was experimentally demonstrated that nitrogen-doped UNCD/a-C:H is applicable as an n-type semiconductor.