Coating of hydroxyapatite thin film by simultaneous vapor deposition

The focus of this study is to utilize a new simultaneous vapor deposition (SVD) technique and produce bioceramic hydroxyapatite (HAp) thin film. Two precursors, CaO and P2O5, were evaporated simultaneously by electron evaporation source and resistive heater respectively. The process parameters, such as deposition rate, substrate temperature, annealing temperature and time were chosen so as to obtain structures, ranging from amorphous and mixed crystalline phases to crystalline HAp. The thin films produced were annealed at different elevated temperatures and the degree of crystallinity was revealed using X-ray diffraction (XRD). The surface microstructure and morphology were investigated by means of atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS), Rutherford backscattering spectroscopy (RBS) and electron probe microanalyzer (EPMA) equipped with energy dispersive X-ray (EDX) detector, were employed for further characterization. By choosing optimum parameters, Ca/P ratio values close to stoichiometry were achieved and uniformly deposited coatings with proper elemental distribution were obtained. (C) 2000 Elsevier Science B.V. All rights reserved.