A hard graphitelike hydrogenated amorphous carbon grown at high deposition rate (>15 nm/s)

Hard graphitelike hydrogenated amorphous carbon with distinct infrared absorption spectra in the C–Hx stretching region is reported. These spectra are characterized by two separated peaks corresponding predominantly to sp3 CH and sp2 CH stretching modes and reveal a distinct absence of endgroups (sp2 CH2 and sp3 CH3). The relatively dense films (~2.1 g/cm3) have low hydrogen content (~20%), high refractive index (~2.4 at 3 µm), nanohardness exceeding 16 GPa, and a characteristic optical dispersion relation. These films are deposited at growth rates >15 nm/s, in the absence of high-energy ion bombardment, indicating the importance of the specific Ar–C2H2 chemistry of the remote plasma used.