Fabrication and characterization of doped zinc oxide thin films by RF magnetron sputter

Farah Lyana Shain (2017) Fabrication and characterization of doped zinc oxide thin films by RF magnetron sputter. Masters thesis, Universiti Malaysia Sabah.

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Abstract

To enhance the productivity of ZnO thin film, the interest in doping ZnO is to explore the possibility of improving ZnO physical and electrical properties. Therefore this research describe the fabrication and characterization of three different materials which is undoped Zinc Oxide (ZnO), Aluminium doped ZnO (Al doped ZnO), and Gallium doped ZnO (Ga doped ZnO) to investigate the effect of Al2O3 and Ga2O3 into the characteristic of ZnO thin film. RF Magnetron sputtering is used in this study because of the advantages sputter in term of ability to produce high quality thin film with a high density and good adhesion interaction between surfaces, and can be obtained at low substrate temperature with good uniformity of the film thickness in a large scale. In order to analyze the favorable combinations of deposition parameters towards thin film quality deposited by Radio Frequency (RF) Powered Magnetron Sputtering, nominal thickness, substrate temperature and deposition pressure were chosen as variable deposition parameters. The experimental finding shows that present of dopant in ZnO thin film improved it electrical properties. Combination of 400 nm nominal thicknesses, substrate temperature at 250°C and low deposition pressure at 2 mTorr produce high quality of thin film in term of structural, optical, and electrical. Higher substrate temperature decreased the surface roughness value. Analysis of structural structure of doped ZnO thin films reveals ZnO, Ga Doped ZnO and Al doped ZnO thin films has be successfully deposited on glass substrate where all the peak observed indicate ZnO, Ga doped ZnO and Al doped ZnO thin film prepared by RF sputtering are polycrystalline with preferential orientation of (0 0 2) similar to the XRD peak pattern for standard ZnO (JCPDS 36-1451).The largest crystallite grain size obtain is Ga doped ZnO which is 27.9 nm. The transparency were differ in different deposition time, substrate temperature and deposition pressure but still show great transparency of film above 80% for all samples. Optical band gap of all thin films deposited is varied from 3.3 eV to 3.46 eV. The lowest resistivity achieved is 1.25 X 10-2 Ω cm. Simple junction diode were fabricated and analysis revealed that for heterojunction for ZnO with Cu2O have the higher ideality factor of 14.5 compare to 12.31 for heterojunction for Al doped ZnO with Cu2O and 11.93 for heterojunction for Ga doped ZnO with Cu2O. Higher ideality factor may cause by limitation of higher series resistance from all samples. Both Ga doped ZnO and Al doped ZnO have lower resistivity and ideality factor from undoped ZnO which is related to the presence of Al3+ and Ga3+ ions in Ga doped ZnO and Al doped ZnO thin films. Research conclude that in this study of Ga2O3 deposited at substrate temperature at 250°C and low deposition pressure at 2 mTorr were favorable dopant compare to Al2O3 due to improvement of electrical properties in Ga doped ZnO compare to Al doped ZnO. Smaller difference of ionic radii of Ga3+ ions with Zn2+ compare with Al3+ given Ga2O3 priority and minimize the defect and improved thin film quality.

Item Type:	Thesis (Masters)
Keyword:	ZnO thin films, Aluminium-doped ZnO, Gallium-doped ZnO, Magnetron sputtering, Electrical properties, Optical properties, Crystallinity, Resistivity, Heterojunctions
Subjects:	T Technology > TP Chemical technology > TP1-1185 Chemical technology > TP200-248 Chemicals: Manufacture, use, etc.
Department:	FACULTY > Faculty of Science and Natural Resources
Depositing User:	DG MASNIAH AHMAD -
Date Deposited:	07 Feb 2025 11:32
Last Modified:	07 Feb 2025 11:32
URI:	https://eprints.ums.edu.my/id/eprint/42789

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