Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/13235
Title: Growth and characterisation of cobalt doped zinc oxide
Authors: TAY MAUREEN
Keywords: cobalt doped zinc oxide, extrinsic ferromagnetism
Issue Date: 25-Mar-2008
Source: TAY MAUREEN (2008-03-25). Growth and characterisation of cobalt doped zinc oxide. ScholarBank@NUS Repository.
Abstract: Spin-transport electronics (or spintronics) command large interest in recent years as they are hyped to be able to exploit both charge and spin in electronic materials, not possible in conventional electronics, based on semiconductors. Dilute Magnetic Semiconductors (DMS) promises combined properties of existing semiconductor technologies with ferromagnetism. Immense attention is being put into fabrication and characterization of room temperature ferromagnetic semiconductors, as it is a fundamental prerequisite for industrial applications.This thesis aims to understand several fundamental issues, which have not been well explored so far, specifically in cobalt doped zinc oxide system. These problems are include: (1) lack of systematic correlation of observed ferromagnetism to magnetic, optical and electrical measurements, and (2) complications by secondary phases. A systematic study of ZnO:Co thin films grown on (0001) sapphire substrates by co-sputtering with Al, through a Al2O3 target, has been carried out.The structural, optical, magnetic and electrical properties of all the samples were carried out systematically in a wide temperature. Results obtained showed that correlated ferromagnetism is present only in samples with cobalt content greater than 25%. In contrast, samples with less than 20% cobalt doping exhibit weak ferromagnetism, strong sp-d interactions and carrier localization. Based on the results from the systematic studies, we conclude that the ferromagnetism in sputtered ZnO:Co films prepared is of extrinsic origin.
URI: http://scholarbank.nus.edu.sg/handle/10635/13235
Appears in Collections:Ph.D Theses (Open)

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2. Abstract.pdf34.91 kBAdobe PDF

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3. Table of Contents.pdf26.49 kBAdobe PDF

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4. List of figures.pdf77.54 kBAdobe PDF

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8. Chapter 1.pdf192.95 kBAdobe PDF

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9. Chapter 2.pdf1.16 MBAdobe PDF

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10. Chapter 3.pdf497.22 kBAdobe PDF

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15. Publications.pdf50.82 kBAdobe PDF

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