Pulsed laser deposition of thin carbon films on SiO2/Si substrates

Abstract

Pulsed laser deposition (PLD) of thin carbon films on SiO2/Si substrates was performed and the resulting films were examined by X-ray photoelectron spectroscopy, transmission electron microscopy (TEM), Raman spectroscopy and ellipsometry. The deposition process was accomplished by laser ablation with Nd:YAG laser (third harmonic λ = 355 nm, pulse width τ = 18 ns and a repetition rate of 10 Hz) on 320–420 nm SiO2/(001) Si substrates with surface area of 15 × 15 mm2. The laser ablation process was carried out in two different deposition regimes: i) continuous regime with a deposition time of 15–1800 s; and (ii) pulse mode. As a target, carbon microcrystalline graphite disks (OD 15 mm, thickness 0.5 mm) were used. We established that films consisting of graphite nanoparticles/graphene grains of 5 to 30 nm thickness were deposited by the continuous PLD process while films comprising one to few-layered nano-sized graphene were deposited by pulsed PLD. Some films have low resistance (ρ = (0.1–1.5) × 10−3 Ω·m) and consist predominantly of sp2 hybridized carbon with Raman spectrum, which resembles that of nano-sized graphene. Regardless of the PLD process used, we observed an interface film enriched with sp3 hybridized carbon, which could be related to CO, CH and other interface bonds.