Plasma-assisted pulsed laser deposition of carbon films: Effect of oxygen plasma on amorphous carbon film etching

Amorphous carbon (a-C) films were deposited on Si substrates by oxygen plasma-assisted pulsed laser deposition (oxygen PAPLD) technique and were compared with those deposited by PLD in oxygen gas. The film properties were characterized by spectroscopic ellipsometry and X-ray photoelectron spectroscopy. It was shown that the films obtained by the oxygen PAPLD at a substrate temperature, Tsub ∼150 °C, were “diamond-like”, while those by PLD in oxygen gas at Tsub = 550−625 °C were “graphite-like”. This difference could be explained by a high etching rate of sp2 bond in a-C films in oxygen plasma. In the optical emission spectra obtained from carbon ablation plumes near substrate in the oxygen PAPLD, the strong emission bands of CO and CO+ were observed, which could be a proof of the etched molecules by atomic oxygen produced in oxygen plasma.