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تحضير اغشية رقيقة من اوكسيد الخارصين ZnO النقي والمشوب بالالمنيوم باستخدام تقنية المحلول ودراسة خواصها البصرية (Sol - Gel) الغروي وتطبيقها كمتحسس غازي == Preparation of Pure and Doped with Aluminum Zinc Oxide (ZnO) Thin Films by Using (Sol - Gel)Technique and the Study of Optical Properties and Applications as A Gas Sensor
Author name:
سعد عبد الله جبر الفاضلي
General topic:
Physics
Specific topic:
Physics
Degree:
Master
University:
University Of Basrah - College Of Education For Pure Sciences
Language:
Arabic
University location:
Basrah
First pages:
26T1676 - p.pdf
Abstract:
In this study, Zinc Oxide (ZnO) thin films are prepared by using Sol - Gel technique . The samples are prepared with different thicknesses (58,69,77)nm . Different weight ratio of Aqueous aluminum chloride (AlCl3.6H2O) are added to the Sol - Gel ZnOwith percentage (0.345%, 0.824% , 1.703% and 2.146%). These solutions are deposited by using spin coating on glass substrate .In order to investigate the sensitivity and the response of these samples for the detection about different vapors and gases (ethanol , methanol , acetone and nitrogen ) , pure and (AlCl3.6H2O) doped ZnO films are prepared by using the same technique but by adding Aluminum electrodes on these films with dimensions (2.5x0.5)cm2 .This preparing is followed by thermal treatment for these films by using oven with temperature reaches to 450 oC.The structure properties of these films are studied by using X - ray diffraction (XRD) and the results show that these films are polycrystalline and the calculated lattice constant are close to the standard values . The samples are analyses by Field Emission Scanning Electron Microscopic (FESEM) and the results show that the grain arrangement are regular and these structures are packed and the grain shape is as spherical . But for the AZO films , we notice that the increasing of the doping percentage reduces the gra in size .We also study the optical properties of these films such as Absorption (A) , Transmission (T) , Reflection (R) , Absorption coefficient (α) , extinction coefficient (k) , the energy gap(Eg) , refractive index (n) , with its complex and real dielectric constant( ) , dissipation factor (tanδ) , Optical Dispersion Parameters (Eo , Ed) and optical conductivity ( ) . The effect of the films thickness on the optical properties of the ZnO films for the over mentioned parameters . The results we get are discussed and compared with other studies . This work elucidates and analyzes the studying of the effect of adding (AlCl3 . 6H2O) o Zinc Oxide (ZnO) and the results are with standards agree with the results of many other researchers . The optical constant are tabulated and compared with , the results of other . And in order to determine the electronic transitions type , Absorption coefficient is calculated and it shows that ZnO and AZO films have transition of direct type because the values of α > 104 . The energy gap of the ZnO films with different thickness (58,69 and 77) nm is calculated , since it is found that the increasing of the film thickness gives slight increasing in the energy gap . The experimental results show that the increasing of doping percentagein ZnO film increases the energy gap with very little amount . In the electronic application field , the study also included design and fabrication of gas sensor system from local materials , which contain of chamber that made of plates polymer that contain of base for install the sample , electrodes to link the sample the measurement circuit , glass flask with three holes , heater , N2 gas cylinder , glass tubes , valves and the measurement circuit electric .The study also includes the ability of responding of the films for the thicknesses (58 , 69 and 77 )nm , to these gases , and it is found that the highest response was at vapor ethanol at the thickness 58nm. The effect of chloride Aluminum on the response of these percentage (0.345% , 0.824% , 1.703% , 2.146%) is studied for the mentioned gases , and it is found that the highest response we get is 45% at the concentration 2.146% for methanol gas . The results are tabulated , discussed and compared with precedent studies.
