Influences of Ambient Gases on the Structure and the Composition of Calcium Phosphate Films Prepared by Pulsed Laser Deposition

Abstract

Calcium phosphate films were prepared by using a pulsed KrF-laser deposition (PLD) method with a hydroxyapatite target in various ambient gases, such as Ar, O2 and H2O. The influence of the ambient gas on the properties of the deposited films was investigated. The chamber pressure and the substrate temperature were fixed at 0.25 Torr and 600℃, respectively. Calcium-rich amorphous calcium phosphate films were deposited with a low density in Ar due to the preferential resputtering of phosphorus from the growing film. In an O2 ambient, the density and the Ca/P ratio of the films were similar to those of the target. However, the deposited film was amorphous calcium phosphate and did not contain OH− groups. Polycrystalline hydroxyapatite films can be deposited in a H2O ambient because a sufficient supply of OH− groups from the ambient gas is essential for the growth of a hydroxyapatite film.