Preparation of carbon nanoparticles by plasma-assisted pulsed laser deposition method : size and binding energy dependence on ambient gas pressure and plasma condition

摘要

Nanometer-size carbon particles were prepared on a Si substrate using pulsed laser deposition (PLD) assisted by radio frequency (RF) Ar plasma and were compared with ones prepared by PLD in vacuum and Ar gas. In both the plasma and gas ambiences, experiments were carried out in Ar pressure pAr ranging from 0.13 to 13 Pa. The particle size increased as pAr increased. However, the size obtained in the RF Ar plasma was approximately 1.5 times larger than that prepared in the Ar gas. An X-ray photoelectron spectroscopy (XPS) analysis revealed that the carbon film covered by the particles was in an amorphous state. The sp3/sp2 carbon ratio of the film was evaluated by deconvolution of XPS carbon (1s) spectra into three components, which are attributed to diamond (sp3), graphite (sp2) and carbon oxide components. The highest sp3/sp2 ratio was 0.4 in the Ar gas and Ar plasma at pAr = 0.13 Pa. The sp3/sp2 ratio decreases monotonously, as the particle size increases. The ratio obtained in the Ar plasma is larger than that in the Ar gas. The effects of pAr and plasma for nanoparticle characteristic are discussed.