Optical properties 39 Zinc oxide 23 Thin films 22 Energy gap 20 Scanning electron microscopy 19 Fibers 17 Sol-gels 15 Substrates 15 Electronic equipment 14 Thermoelectric equipment 14 Article 13 Fiber optic sensors 13 Refractive index 13 X ray diffraction 13 Fiber lasers 12 Optical radar 12 Field emission microscopes 11 II-VI semiconductors 11 Optical fibers 11 Sol-gel process 11 Concentration (process) 10 Field emission scanning electron microscopy 10 Atomic force microscopy 9 Erbium 9 Light absorption 9 Titanium dioxide 9 human 9 Graphene 8 Nanorods 8 Optical pumping 8