Strain-related phenomena in TiO2 nanostructures spin-coated on porous silicon substrate

Abstract

In this study, anatase TiO2 nanostructures were synthesized on silicon and porous silicon (PS) substrates by sol–gel spin coating. The PS template was formed by electrochemical anodization on p-type silicon wafer. The field emission electron microscopy (FESEM) images showed a uniform morphology with average diameter of 15nm and 20nm for PS and TiO2 nanostructures, respectively. The X-ray diffraction studies of residual stress and detailed discussion about intrinsic and extrinsic stresses as its origins are presented. Measurements reveal the presence of compressive strain in the TiO2 layer with negative dilatation about 1.83%. A reduction of thermal stress of TiO2 layer deposited on PS substrate compared to silicon substrate was shown. We also used Williamson–Hall (W–H) method to study the individual contributions of crystallite sizes and microstrain on the peak broadening of the TiO2 nanostructures. Our obtained results showed that the mean crystallite size of the TiO2 nanostructures estimated from the FESEM and W–H analysis were highly in agreement.