Influence of the substrate bias on the stoichiometry and structure of RF-magnetron sputter-deposited silver-containing calcium phosphate coatings.

A coating on the basis of silver-containing hydroxyapatite (silver-hydroxyapatite) was deposited by radio frequency (RF) magnetron sputtering. X-ray diffractometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and ellipsometry were used to analyse the change in structure and stoichiometry of the coatings upon the change of the negative electrical bias (-50 V and -100 V) on the substrate. The chemical composition of the sputter-deposited coating was identical to the target. However, an increase in the negative electrical bias on the substrate led to a decrease of the coating thickness. In addition, the average size of the grains decreased from 55 ± 15 nm (grounded substrate) up to 30 ± 10 nm when an electrical bias of -100 V was applied. [ABSTRACT FROM AUTHOR]