Enhanced Field Emission of ${\rm TiO}_{2}$ Nanowires With UV Illumination

TiO₂ nanowires with rutile structures on a SiO₂/Si substrate were grown by thermal evaporation. A field-emission property of the low turn-on field was reduced to 3.5 and 2.6 V/μm under UVA in 10 min and UVC in 25 min. The wavelength of UVC was higher than the TiO₂ band-gap, so the electrons more easily tunneled to the vacuum level and generated excess heat that lowered the turn-on field emission from under UVA. The work function of samples that had been exposed to UVA for 10 min and UVC for 25 min were reduced to 3.10 and 2.02 eV, respectively.