Growth of ultrananocrystalline diamond film by DC Arcjet plasma enhanced chemical vapor deposition

► We grew ultrananocrystalline diamond film by DC Arcjet plasma enhanced CVD. ► We found a new morphology, the “pineapple-like” morphology, on the growth surface. ► The dominant surface was (100) in the film with the “pineapple-like” morphology. ► There was nano-structured feature in Raman spectra of the “pineapple-like” film. ► The gradient of the density of the gas phase was different in different growth cases.