Abstract
Herein, we report the successful non-catalytic growth of well-crystallized ZnO nanoneedles on Si(100) substrates via thermal evaporation process using high-purity metallic zinc powder and oxygen. The grown nanoneedles were characterized by several techniques. The detailed morphological
studies by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) revealed that the materials possess nanoneedles-shaped morphologies which are quasi-aligned and grown in high density over the whole substrate surface. The compositional properties confirmed
that the prepared nanoneedles are pure ZnO. The optical property of the prepared nanoneedles were examined by room-temperature photoluminescence (PL) spectroscopy which confirmed that the prepared nanoneedles exhibit excellent optical properties. The field emission analysis for ZnO nanoneedles
exhibits a turn-on field of 9 V/μm at the current density of 1.62 μA/cm2. Further, the high emission current density of about 1.53 mA/cm2 at the applied electric field of 37 V/μm was also observed. The calculated field enhancement factor
'β', from the F-N plot, was found to be 3086.