Diamond-like carbon layers modified by ion bombardment during growth and researched by Resonant Ultrasound Spectroscopy

Abstract

Biocompatible Diamond-Like Carbon (DLC) films were prepared by Pulsed Laser Deposition technique using the laser energy density of 10Jcm−2 on the graphite target. The surface of the grown film was modified during the deposition by bombardment with argon, xenon, nitrogen or oxygen ions. The ion energy (up to 150eV) was changed by gun voltage and by ionic current. The films with high and low diamond/graphite content were prepared. Physical and mechanical properties of biocompatible DLC thin layers prepared by hybrid laser technology were studied. The composition of layers and the content trace elements were determined by the methods of Rutherford Backscattering Spectrometry and Particle Induced X-ray Emission. The content of sp2 and sp3 bonds was measured using X-ray Photoelectron Spectroscopy. For different energy of argon and oxygen ions the maximum of sp3 bonds content was found (83.63% of sp3 bonds for argon ions). All films were smooth, which was confirmed by profilometry and Atomic Force Microscopy measurements. Maximum roughness Ra and RMS was did not exceed 1nm. The Younǵs and shear moduli were studied by Resonant Ultrasound Spectroscopy. The Young’s Modulus attained the value of 601GPa and the shear Modulus attained the value of 253GPa at the energy of 30eV of Ar ions. The influence of ion bombardment on DLC film properties is discussed.