Gas-phase and film analysis of hydrogenated amorphous carbon films: Effect of ion bombardment energy flux on sp(2) carbon structures

摘要

Hydrogenated amorphous carbon (a-C:H) films comprise nanoclustering graphites (nc-G), fused aromatic rings (nR), and olefinic chain clusters (nC) of sp(2)-bonded carbons in an sp a matrix. In this study, the sp(2) composition of the nc-G, nR and nC in a-C:H films is found to be determined by the ion bombardment energy flux (Gamma(Ei)), which can be estimated as the product of ion bombardment energy and ion flux onto the deposited surface, in plasma-enhanced chemical vapor deposition using a plasma mixture of H-2 and CH4 gases with the H radical injection method. The sp(2) composition is analyzed using Raman spectroscopy and near-edge X-ray absorption structure spectroscopy. a-C:H becomes increasingly graphitized with increasing Gamma(Ei). The precise control of the sp(2) C structure composition can be achieved by controlling the very-high-frequency input power and radio frequency input bias power via the ion flux and ion bombardment energy.