Oxygen Vacancy Driven Modulations in In2O3 Pyramidal Beaded Nanowires

We present the growth of pyramidal beaded In2O3 nanowires by using hydrogen assisted thermal evaporation. Reduction reaction at the source produces different growth species having varying vapor pressures, which is responsible for the growth of oxygen deficient nanostructures. The number and nature of oxygen vacancies affect the growth rates of different planes and thus the ultimate nanostructure morphology. A detailed growth mechanism of the nanowires is proposed on the basis of thus created oxygen vacancies. Morphology of the synthesized nanostructures was interpreted using electrical and structural analysis (VESTA) software. Structural, compositional, optical and field emission (FE) characteristics were studied to further confirm the oxygen deficient growth. The phonon confinement model (PCM) was used to calculate the correlation length of defects. The regarded nanowires were found to be good field emitters with low turn-on fields, from 5.8 to 14.5 V/mu m, and field enhancement factors from 1775 to 362, depending on cathode sample distances. The experimental FE data were fitted with the Philips model and two-region field emission (TRFE) model, and the screening effect, absolute amplification factor and width of field enhancement region were calculated. Our approach to fabricate beaded nanowires may open new avenues to synthesize unique nanostructures for novel optoelectronic devices.