Diamond like carbon films with embedded Cu nanoclusters deposited by reactive high power impulse magnetron sputtering: Pulse length effects

Abstract

In the present study diamond like carbon films with embedded Cu nanoclusters (DLC:Cu films) were deposited by reactive high power impulse magnetron sputtering (HIPIMS). HIPIMS pulse length (pulse on time) effects were considered. The dependence of the chemical composition on pulse length was found. Structure of diamond like carbon matrix of the nanocomposite films studied by Raman scattering spectroscopy has indicated weak increase of the sp3/sp2 carbon bond ratio with HIPIMS pulse length. Studies of the shape and dimensions of copper nanoclusters performed by He ion microscopy have shown that increase of the HIPIMS pulse on time resulted in increased number of the nanoclusters and subsequent increase of the Cu nanoclusters size. Study of optical properties revealed surface plasmon resonance effect in all investigated films. Correlation between the optical absorption spectra and photoexcited charge carrier relaxation time recorded by the pump probe spectroscopy was found. The highest relaxation time was observed at the excitation wavelength close to the absorption surface plasmon resonance peak wavelength The highest maximum relaxation time was observed for the DLC:Cu film deposited by using HIPIMS pulse of 400 μs on time. It was explained by the dependence of the relaxation time on Cu nanocluster size.