Growth of NbC thin film using CH₄ as a carbon source and reducing agent

Transition metal carbides (TMCs) have high melting points, hardness, and chemical stabilities in acidic media. In this work, a chemical vapor deposition method using CH₄ as a carbon source and reducing agent was employed to make an NbC film. NbCl₅ carried by Ar gas was used as an Nb precursor. An NbC thin film, deposited on a c-plane sapphire, exhibited a preferential orientation of the (111) plane, which can be explained by domain-matching epitaxy. A nanoindentation test showed that the NbC film with the preferential orientation of the (111) plane was stronger than that with a random orientation. Moreover, the results showed that H₂, which is conventionally used as a reducing agent in NbC synthesis, degraded the crystallinity and hardness of the fabricated NbC.