Titanium dioxide thin films were deposited on crystalline silicon substrates by electron beam physical vapor deposition. The deposition was performed under vacuum ranging from 10−5to 10−6Torr without process gases, resulting in homogeneousTiO2-xlayers with a thickness of around 100 nm. Samples were then annealed at high temperatures ranging from500°C to800°C for 4 hours under nitrogen, and their structural and optical properties along with their chemical structure were characterized before and after annealing. The chemical and structural characterization revealed a substoichiometricTiO2-xfilm with oxygen vacancies, voids, and an interface oxide layer. It was found from X-ray diffraction that the deposited films were amorphous and crystallization to anatase phase occurred for annealed samples and was more pronounced for annealing temperatures above700°C. The refractive index obtained through spectroscopic ellipsometry ranged between 2.09 and 2.37 in the wavelength range, 900 nm to 400 nm for the as-deposited sample, and jumped to the range between 2.23 and 2.65 for samples annealed at800°C. The minimum surface reflectance changed from around 0.6% for the as-deposited samples to 2.5% for the samples annealed at800°C.

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In this work, alkaline texturing of (100) crystalline Si and multicrystalline Si wafers in diluted KOH solution leading to pyramidal structures is studied as a function of the etching temperature. The surface morphology is investigated using Atomic Force Microscopy and Scanning Electron Microscopy and the surface reflectance is measured by spectrophotometry in the wavelength range 200-1200 nm. It is found that etching in diluted 1% KOH solution leads to incomplete surface texturing when the etching temperature is equal to 70 o C. The optimum etching temperature is found to be in the range 80-85 o C which results in a minimum surface reflectance for crystalline silicon covered with an antireflection coating of 0.8%, with a uniform distribution over a wider wavelength range for samples that received a saw damage removal in 30% KOH solution prior to texturing. On the other hand, the optimum etching temperature shifts to the higher range 85-95 o C for multicrystalline silicon surface with a minimum reflectance of 4.6% with ARC.