Synthesis and characterization of sol-gel derived calcium hydroxyapatite thin films spin-coated on silicon substrate

The goal of this study was to demonstrate that sol-gel processing route is suitable for the fabrication of calcium hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, CHA) thin films on Si substrate by spin-coating technique. The substrate was spin-coated by precursor sol solution 1, 5, 15 and 30 times. The samples were annealed after each spin-coating procedure at 1000 °C for 5 h in air. In the sol-gel process ethylendiamintetraacetic acid and 1,2-ethandiol, and triethanolamine and polyvinyl alcohol were used as complexing agents and as gel network forming agents, respectively. The coatings were characterized using X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) and Raman spectroscopies, profilometry and the contact angle measurements (CAM). It was demonstrated, that properties of calcium hydroxyapatite thin films depend on spinning and annealing times.