الخواص التركيبية والبصرية والكهربائية لاغشية اوكسيد النيكل المحضرة بطريقة الترذيذ كمتحسس غازي == The structural, optical and electrical properties of NiO films prepared by RF - Sputtering as gas sensor
Author name:
زينب طارق عبد الحميد
Supervisor name:
قاسم عزيز محمد | محمد عبد النبي
General topic:
Physics
Specific topic:
Laser Physics and Electro-optics
Degree:
Doctorate
University:
University of Baghdad - Ibn Al-Haytham College Of Education For Pure Sciences - Physics Department
Language:
English
University location:
Baghdad
First pages:
26T1848 - p.pdf
Abstract:
The structural, optical, electrical, and gas sensing properties of nickel oxide have been studied. The structural properties of the deposited films were made using XRD, SEM and AFM. The NiO films have been prepared with different thicknesses (100, 150 and 200) nm on glass, Si and Al2O3 substrates, using RF - sputtering at 100°C substrate temperature. The electrical and optical parameters of the NiO films were characterized using Hall Effect and transmittance measurements.The X - ray diffraction result indicates that the films are of polycrystalline in nature with cubic structure. The grain size of the nanoparticales observed at the surface depended of films thicknesses, where 200 nm has smallest average grain size 85.5 nm and RMS increased with increasing of thicknesses.The optical characterization shows that the film has band gap that ranged in between 3.6 eV to 3.9 eV, the average transmittance of films was found to be ranged of 60% to 85% in the VIS - IR regions. The dark conductivity of NiO films has been studied as a function of film thickness, crystal structure transformation and temperature with particular regard to gas sensitivity in CO2, NO2, CO, NO and the ethanol vapor. The electrical properties were found to be dependent on the film thickness.I - V characteristics for NiO films at (air, vacuum, N2, O2andCO2) gases before and after annealing were investigation. It would appear from our result that the diminution of the dark conductivity after annealing may be due to the surface contaminations adsorbed on the surface of the NiO film during film preparation or from ordinary atmospheric air.The resistivity of the NiO thin films decreased with increasing of thicknesses, from 1.5x105 to 5.4x104 (Ω.cm), which is related to the increase of carrier concentration with film thickness. The results of measurements of NiO thin films show that these films have good conductivities and results obtained from Hall Effect indicate that the NiO films were (p - type).It was found that the sensitivity to other gases differs for different film thicknesses and working temperature. Furthermore, NiO films exhibits high and fast response to NO2 gas at 200°C, which makes it a promising candidate for a poisonous gas sensing.
