Morphology and Optical Characteristics of TiO2 Nanofilms Grown by Atomic-Layer Deposition on a Macroporous Silicon Substrate

A process for creating a macroporous silicon substrate on which a layer of titanium dioxide was deposited using the atomic-layer deposition method is described. Electrochemical etching was used to form the macroporous structure of the substrate. TiO2 was deposited using an SI PEALD setup. The morphology, structure, and optical properties of the deposited TiO2 film were assessed using scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy, spectral ellipsometry in the range 240-1000 nm, and Raman spectroscopy. Raman spectra revealed peaks at 144, 194, 397, and 639 cm(-1) that were characteristic of the TiO(2 )anatase modification. The absorption coefficient and optical band gap width of the deposited film were determined based on the calculated ellipsometric parameters.