Energy gap 4 Optical band gaps Sol-gel spin coating 3 Sol-gels 3 Zinc oxide 3 Optical band gap energy 2 Optical properties 2 Thin films 2 Titanium dioxide 2 X ray diffraction 2 Absorbance measurements 1 Absorbances 1 Absorption edges 1 Atomic force microscopy 1 Atomic percent 1 Bandgap materials 1 Best value 1 Boron concentrations 1 Crystallite size 1 Current voltage 1 Different precursors 1 Electric properties 1 Electronic equipment 1 Field emission scanning electron microscopes 1 Fourier transform infrared spectroscopy 1 Glass 1 Glass systems 1 Glass transition 1 Glass-forming ability 1 Grain size 1