A novel laser-liquid-solid interaction process for hydroxyapatite formation on porous silicon

Abstract

The mechanism of hydroxyapatite (HA, Ca 10 (PO 4 ) 6 (OH) 2 ) growth on the surface of porous silicon (PS) was examined. PS layers were prepared by electrochemical or chemical etching of n-type Si with (111) orientation, and p-type Si with (100) orientation. HA growth was induced by two methods: a simple soaking process in a simulated body fluid (SBF) and a novel Laser-Liquid-Solid Interaction (LLSI) process which allowed interaction between a scanning laser beam and the PS substrate immersed in the SBF. The grown layers were investigated by light microscopy, electron microprobe analysis, Raman spectroscopy and X-ray diffraction. Differently doped Si substrates with different crystallographic orientation and electrical resistivity were used and their effect on the HA growth, as well as the effect of the laser energy were examined.