Experimental study of hydrogen-free DLC film deposition by XeCl (308 nm) pulsed laser ablation

Abstract

ABSTRACT In this work, hydrogen-free DLC(Diamond Like Carbon) films have been deposited by XeC1(308nm) pulsed laser ablationof pure graphite target with the base pressure of 1 x 1 O Pa at room temperature. The films obtained show remarkableproperties similar to those of diamond. Raman spectroscopy analysis gave a broad Raman peak centered at 1523cm', whichindicated that the film had an amorphous structure. FTIR analysis showed that the film had a transmittance above 90% from2.5 im to 25 jtm without any absorption peak. Microhardness test showed that the film had a mechanical hardness up to23GPa. The film also had chemical inertness in various acids and organic solutions. The effects of experimental parameterson the film properties have been investigated. The optimum dc bias of -500V and the threshold of laser(308nm) powerdensity of 3 x 1 08W/cm2 which is necessary to obtain DLC film have been observed. The emission spectra of laser inducedplasma have been obtained to study the ionization state of particles in laser-induced plasma. Considering the experimentalresults, we suggest that the energy and ionicity of the particles in laser-induced plasma should be important factors in theformation of DLC film. Particles with higher energy and higher ionicity will result in DLC films with excellent properties.Keywords: Diamond-like carbon, Pulsed laser deposition, Excimer laser