以反應式磁控濺鍍沉積AZO透明導電膜之特性研究

Characteristics of transparent conductive AZO films deposited by RF reactive magnetron sputtering

蔡宜蓁(Yi-Chen Tsai)

指導教授 ： 楊木榮

大同大學/工程學院/材料工程學系所/碩士(2007年)

摘要

氧化鋅(ZnO)為一種具纖鋅礦結構之寬能隙半導體，其在太陽能電池、表面聲波元件、氣體感測器等元件中被廣泛的應用。近年來，由於透明導電膜之需求量大，因而有許多研究積極開發透明導電膜之材料，由於AZO具與ITO可比擬之光電性質，且具成本低、無毒性且在氫電漿中具穩定性等優點，因此已成為透明導電膜領域開發欲取代ITO材料之主要項目。
本實驗利用自製之鋅鋁合金靶(Zn-1.1wt%Al ally target)以RF反應式磁控濺鍍法在室溫下於Schott B270光學玻璃基板上沉積透明導電膜AZO(ZnO：Al)，本實驗主要討論改變製程參數(氧分壓、沉積時間及RF 功率)對AZO薄膜電性及光學性質之影響。所製得之AZO薄膜以XRD、SEM、AFM、Hall-effect measurement、UV-VIS等量測分析其性質。結果顯示以XRD分析，所有AZO薄膜在2θ=34°附近均具氧化鋅之(002)從優取向，且無金屬鋅或金屬鋁之繞射峰產生；濺鍍時，僅需通入少量氧氣即可形成透光度佳之薄膜，且光學能隙隨載子濃度之提升而增加，此為藍移的現象，即著名之Burstein-Moss effect。AZO之電性，載子濃度、遷移率及電阻率間之變化可由雜質離子散射及晶界散射來解釋，兩者在不同參數下之透明導電膜內扮演著相互抗衡之角色。

關鍵字

氧化鋅摻雜鋁 ； 反應式磁控濺鍍 ； 透明導電膜

並列摘要

Transparent conductive oxide films (TCOs) have been extensively used in flat panel displays, solar cells, and other optoelectronic devices due to their high transmittance in visible region and low resistivity. Although In2O3:Sn (ITO) are extensively used as transparent conductive oxides in diverse applications, AZO shows good electrical and optical properties which is comparable with ITO films. Furthermore, AZO offers a number of advantages compared to ITO films nowadays: (a) cheap and abundant raw materials, (b) non-toxicity, (c) good stability in hydrogen plasma, which is of significance in applications related to amorphous silicon solar cells. Most papers focused on ceramic targets, however, Zn-Al alloy targets attract great interest in reactive sputtering because of their desirable features including higher deposition rate, easier fabrication of the alloy targets and accurate control of the film thickness. Aluminum-doped zinc oxide films were prepared by radio-frequency reactive magnetron sputtering on Schott B270 glass substrates with Zn-1.1wt%Al alloy target. AZO films were prepared under various deposition parameters. It can be seen that almost all films exhibit strong (002) preferred orientation. Except the film prepared at an oxygen partial pressure of 2%, the average optical transmittance of films in visible range is greater than 80%. The optical band gap of AZO films increases while the carrier concentration increases. This result corresponds with the Burstein-Moss effect. Ion impurity scattering and grain boundary scattering mechanisms can account for the conduction mechanism in TCO films.

並列關鍵字

reactive magnetron sputtering ； Al-doped ZnO(AZO) ； transparent conductive oxide

參考文獻

[4] M. S. Wu, A. Azuma, T. Shiosaki and A. Kawabata, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 36, n 4, Jul, p 442-445, 1989.

[5] W. Water and S. Y. Chu, Materials Letters, vol. 55, pp. 67, 2002.

[7] Y. Igasaki and H. Saito, Thin Solid Films, vol. 199, pp. 223, 1991.

[8] T. Minami, Semicond. Sci. Technol., vol. 20 pp. S35–S44, 2005.

[11] E. S Shim et al., Appl. Surf. Sci. , vol. 186, 474, 2002.