Loading...

Synthesis, Characterization and Field Emission Study of Nickel Oxide (NiOX) Nanostructures

Ebrahimi, Mahdi | 2012

746 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43729 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Moshfegh, Alireza; Sangpour, Parvane
  7. Abstract:
  8. Recently, nickel oxide nanostructures with NaCl-type structure have a variety of applications due to excellent chemical stability, as well as optical, electrical and magnetic properties. In this research, first by using DC and RF sputtering methods,nickel thin films were deposited on Si (100) and glass lame substrates under different experimental conditions (Discharge power, pressure and growth time).The deposited layers were annealed in air at different temperatures to obtain and compare their crystalline structures. Nickel oxide nanostructures grown on the Si (100) were studied by scanning electron microscopy analysis (SEM) to determines surface morphology, atomic force microscopy (AFM) for surface roughness and X-ray photoelectron spectroscopy (XPS) for determining surface chemical compositions. In addition, the band gap energy of annealed films was measured between 3.77-3.87 eV by using optical technique. Atomic force microscopy (AFM) was also utilized to measure surface roughness and compute statistical parameters such as roughness exponent(α), drift (D(1)) and diffusion (D(2)) coefficients.Finally, Field-emission measurements were performed in an indigenously constructed set-up under ultra high vacuum (UHV) conditions. Experimental were carried out with different cathode (synthesized NiO nanostructures)-anode (aluminum probe) spacing distances. Plots of the field emission current density, J, versus the applied electric fields, E , and theirs corresponding logarithmic known as Fowler-Nordheim (FN) plots at different anode-sample separations(vacuum gap) were obtained . In addition, their field emission properties such as turn-on field and field enhancement factor (β)were also determined.The field emission(FE) measurements in different vacuum gaps (d) indicate that the relationship between 1/β and 1/d is a linear function which obeys a two-region FE model. It was also found that the field emission from Nickel oxide nanostructures followed the FN theory. The turn-on emission field and the enhancement factor were found about 3.8V/µm and 5913 at the vacuum gap of 300 µm for the annealed NiO nanostructures, respectively.

  9. Keywords:
  10. Nickle Oxide ; Roghness Exponent ; Field Emission ; Sputtering ; Field Enhancement Factor

 Digital Object List

 Bookmark

No TOC