Crystalline hydroxyapatite thin films produced at room temperature - An opposing radio frequency magnetron sputtering approach

Zhendong Hong*, Lan Luan, Se Bum Paik, Bin Deng, Donald E. Ellis, John B. Ketterson, Alexandre Mello, Jean G. Eon, Joice Terra, Alexandre Rossi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


Hydroxyapatite (HA) films have been widely recognized for their biocompatibility and utility in promoting biointegration of implants in both osseous and soft tissue. Conventional sputtering techniques have shown some advantages over the commercially available plasma spraying method; however, the as-sputtered films are usually amorphous which can cause some serious adhesion problems when post-deposition heat treatment is necessitated. In this paper we present an opposing radio frequency (RF) magnetron sputtering approach for the preparation of HA thin films on various substrates at low power levels. Using this alternative RF magnetron geometry, as-sputtered HA films are nearly stoichiometric, highly crystalline, and strongly bound to the substrate. Post-deposition heat treatment under 800 °C did not result in a marked improvement in the degree of crystallinity of the films. In addition, dissolution experiments show that as-sputtered films are more stable than annealed ones. As-sputtered films grown on amorphous silica substrates exhibit X-ray diffraction (XRD) patterns similar to those of randomly orientated HA powder. On the other hand, films deposited on oriented substrates such as Si(100) and Si(111) show a polycrystalline HA XRD pattern but with some strongly preferred orientations, indicating that HA crystallization is sensitive to the nature of the substrate. The results suggest that the opposing RF magnetron sputtering approach has some potential to produce high quality HA films on metallic implants.

Original languageEnglish (US)
Pages (from-to)6773-6780
Number of pages8
JournalThin Solid Films
Issue number17
StatePublished - Jun 2007


  • Heat treatment
  • Hydroxyapatite
  • Off-axis sputtering
  • RF opposing magnetron sputtering
  • Thin films

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry


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