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    Please use this identifier to cite or link to this item: https://ir.lib.ksu.edu.tw/handle/987654321/6332


    Title: 摻雜過渡元素原子之氧化鋅奈米薄膜之物理性質研究
    Authors: 呂正中
    莫定山
    盧陽明
    邱建文
    鍾華榮
    Keywords: DMS
    Thin films
    ZnO
    Optical energy gap
    Date: 2007-07-31
    Issue Date: 2009-12-30 10:23:23 (UTC+8)
    Abstract: 氧化鋅薄膜由於具有良好之光學、壓電及導電等特性,且具有無毒及價格較低等優點,其被廣泛地應用在許多科技的領域上,例如透明導電材料(用以取代ITO),氣體感測器、太陽能電池、表面聲波裝置以及壓電變頻器等用途上。因此對氧化鋅薄膜之結構、電性以及其它性質能充分掌握對於其應用上乃是相當重要且必須的。過去對於氧化鋅薄膜之物理性質之研究很多,然而對於摻雜其他元素對氧化鋅薄膜性質之影響著墨不多,因此還值得深入做探討。在本研究計劃中,我們選擇過渡金屬為摻雜元素。在過去摻雜過渡金屬元素的氧化鋅薄膜研究報告主要是針對其結構、光學能隙(optical energy gap)以及導電性做研究。在過去的報告當中,當摻雜適當的成份比例之Ti 時,其導電性可以大為增進;甚至有研究宣稱在摻雜Ti 元素之氧化鋅薄膜中觀察到半導體-金屬性導電行為的轉變。而一般相信,摻雜過渡金屬元素氧化鋅薄膜導電性之增進以及半導體-金屬性導電行為的轉變主要是肇因於能隙縮減效應(band-gap shrinkage effect)以及由於摻雜Ti4+離子所導致之自由載子增加效應。而在另一方面,摻雜磁性離子之氧化鋅薄膜由於可以成為室溫的鐵磁性 DMS,更引起廣泛的興趣。所謂DMS(diluted magnetic semiconductors)指的是在半導體合金材料中摻雜少量之磁性離子。自從在Ga1-xMnxAs 發現鐵磁性以來,DMS 一直就吸引著廣泛注意的目光,因為其可以成為”自旋源(spin source)”或成為”自旋注入器(spin injector)”,對於發展自旋電子學(spintronics)領域來言,將是相當具有潛力的材料。然而,對於DMS 材料中鐵磁性的來源,一直以來還存在著爭議。好幾種技術可以用來製備透明氧化鋅薄膜,比如說” 金屬有機化學氣相沉積法(MOCVD,metal organic chemical vapor deposition)、溶膠-凝膠浸鍍法(sol-gel)、化學反應沉積法(chemical reactive evaporation)、直流-射頻磁控共濺鍍法(DC and RF magnetron co-sputtering)等等。在本研究中,摻雜過渡金屬元素氧化鋅薄膜將以直流-射頻磁控共濺鍍法合成。而我們將量測用X-光繞射、電阻率、磁化率、X-光吸收光譜、EDS、光學穿透光譜以及霍爾效應,用以研究摻雜不同過渡金屬元素之氧化鋅薄膜的物理性質。另外,我們也將在本研究中討論其可能之應用。
    ZnO films exhibit many remarkable characteristics due to their good optical quality, stability, excellent piezoelectric properties, low cost and nontoxicity…etc. They are widely used in various technological domains, such as transparent conducting materials, gas sensors, solar cells, surface acoustic wave devices and piezoelectric transducers. Good knowledge of structural, electrical, and other properties of ZnO films is necessary for its applications. The physical properties of ZnO films have been investigated widely. However, the doping effect on its properties is still under investigation. In this research, we choose transition metal atoms as dopants. In transition-metal doped ZnO films, previous reports focused on their structural, optical energy gap, and conductivity behaviors. In Ti-doped ZnO films, the conductivities were enhanced by doping appropriate Ti content. Moreover, a semiconductor-metal transition was observed in the ZnO: Ti films. It is believed that the enhancement of conductivity and the semiconductor-metal transition is resulting from the band-gap shrinkage effect and the increase of carrier concentrations originating from Ti4+ doping. On the other hand, the magnetic-ion doped ZnO films, being an excellent candidate for aferromagnetic DMS at room temperature, attracted especial interests. DMSs (dilute magnetic semiconductors) are referred to semiconductor alloys formed by randomly replacing some fraction of the host atoms in a semiconductor with the magnetic elements. Since the discovery of ferromagnetism in Ga1-xMnxAs, DMSs have attracted much attention as promising materials in evolving area of spintronics due to the possibility of a spin source or spin injector in spintronic devices. However, the nature of ferromagnetism in DMSs remains controversial. Several technologies are used to prepare transparent conductive zinc oxide such as metal organic chemical vapor deposition, sol-gel, chemical reactive evaporation, DC and RF magnetron co-sputtering. In this work, transition-metal doped ZnO films will be deposited by simultaneous RF sputtering of ZnO and DC magnetron sputtering. X-ray diffraction, electrical resistivity, susceptibility, EDS, X-ray absorption spectrum, optical transmission spectrum, and Hall-effect measurements will be exploited in order to study the properties of the ZnO films. The possible applications of the transition-metal doped ZnO films will also be discussed this research.
    Appears in Collections:[機械工程系所] 研究計畫

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