Preparation of hydrogenated amorphous carbon films from polymers by nano- and femtosecond pulsed laser deposition

Abstract

Hydrogenated amorphous carbon (a-C:H) films can be simply produced by pulsed laser deposition (PLD) from targets containing hydrogen and carbon, e.g. polymers. Films deposited from polyethyleneterephtalate (PET) and polycarbonate (PC) were compared to samples prepared from glassy carbon. Several lasers were used to explore the influence of pulse duration (∼30 ns and ∼500 fs) and wavelength (248 and 193 nm) on the properties of laser deposited films. The film composition was characterized by Rutherford backscattering spectrometry and elastic recoil detection analysis. Variable angle spectroscopic ellipsometry gave information about the thickness and optical properties of the films. It was demonstrated that a consistent interpretation of the laser ablation, caused by rather different laser sources on various targets, is possible using the parameter of volumetric power density (intensity divided by light or heat penetration depth). PLD from polymer targets resulted in amorphous hydrogenated films, where hydrogen and oxygen content was decreased compared to the composition of the original target. PLD from glassy carbon target resulted in graphitic, diamond like and porous carbon films with increasing volumetric power density.