Bias effects on structure and piezoresistive properties of DLC:Ag thin films

In present study silver containing diamond like carbon (DLC:Ag) films deposited by reactive unbalanced magnetron sputtering of silver target in argon and acetylene gas ambient were investigated. Structure of the deposited films was studied by multiwavelength Raman spectroscopy, and chemical composition — by X-ray photoelectron spectroscopy (XPS). The X-ray diffraction (XRD) as well as transmission electron microscopy was employed in the analysis of films. The effects of the substrate bias on structure, chemical composition and piezoresistive properties of DLC:Ag films were investigated. Silver and oxygen atomic concentrations in the DLC:Ag films decreased with the increase of the negative substrate bias. Relationship between the structure of DLC:Ag films and substrate bias was observed, too. Dependence of the piezoresistive gauge factor of DLC:Ag films on the substrate bias was resonance type with the highest gauge factor values observed in 50–100 V negative voltages range. It was found that gauge factor of the DLC:Ag films is related both with structure of the diamond like carbon matrix and silver atomic concentration and size of the silver clusters in the deposited films.