Effects of non-depositing energetic species during the growth of boron nitride and amorphous carbon thin films by sputter deposition

We study the effect of ion irradiation during the growth of boron nitride (BN) and amorphous carbon (a-C) by sputter deposition. We found that the dominant effects for the BN growth are the subplantation of N+ and B+ species. For energies higher than the threshold for Ar+ subplantation, the Ar+ penetrates into BN and disrupts the BN bonds resulting in defective BN. The existence of Ar impurities in such films promotes the stability of C impurities. These effects result in a very narrow window of ion energy (<40 eV width) where successful growth of BN films may be achieved. On the other hand, in a-C films, sp3-bonded C, we found a close correlation between the Ar impurities with the sp3-content, which suggests that Ar impurities promote the formation of sp3-bonded carbon in a-C, in contrast to BN growth.