利用離子佈植法摻雜鈦之氧化鋅奈米線的合成與光電性質探討

Synthesis and Optoelectronic Properties of Ti-doped ZnO Nanowires by Ion Implantation

宋咏樵(Yung-Chiao Sung)

指導教授 ： 施漢章

國立清華大學/工學院/材料科學工程學系/碩士(2008年)

摘要

本工作主要在研究利用離子佈植的方式來合成摻雜鈦的氧化鋅奈米線並探討其光電特性。我們先利用熱蒸鍍法在爐管中合成出氧化鋅奈米線，然後藉由金屬蒸氣真空電弧(MEVVA)技術去使鈦的靶材離子化，透過加速電壓植入氧化鋅奈米線的結構中完成摻雜的動作。
由SEM與TEM的影像可以發現在摻雜前後表面形貌與微結構並不會因為鈦離子的摻雜而有所改變；透過EDS與XPS的成分分析可以確定鈦摻雜的濃度隨佈植劑量的不同從0.33%至2.36%；從XRD繞射圖與Raman光譜分析上沒有出現二氧化鈦的訊號，表示鈦可能是以原子的方式存在於氧化鋅結構當中。
性質分析方面，CL光譜分析可以觀察到在摻雜後的紫外光峰值有先藍移後紅移的現象，表示鈦的摻雜濃度可能導致氧化鋅的光學能隙寬化或窄化。電性量測方面，因為鈦的摻雜使得單根氧化鋅奈米線的電阻率由0.122Ωcm下降至0.035Ωcm，減少了71.3%。同時因為氧化鋅本身的壓電效應的影響，在受到應力後的電阻率反而上升。場發射方面也因為摻雜的關係，使得性質有所提升。

關鍵字

摻雜鈦氧化鋅 ； 金屬蒸氣真空電弧 ； 陰極激發光 ； 電阻率 ； 場發射

並列摘要

In this work, Titanium-doped Zinc oxide (Ti-doped ZnO)
nanostructures were synthesized by a two-step method and characterized. At first, the pure ZnO nanowires were synthesized by the thermal evaporation in a CVD process. Then the as-synthesized nanowires were doped with Titanium by the Metal vapor vacuum arc (MEVVA) system.
From the FESEM and HRTEM observation, the morphology and the microstructure of the ZnO nanowires did not change after Ti doping. From the composition analysis of EDS and XPS, the Ti concentration increased from 0.33% to 2.36% with different dosages. The XRD and Raman spectrum showed no signal of titanium oxide, indicating that titanium existed in the ZnO structure in atomic state.
We can find that the peak of UV emission shift to the higher energy region in the beginning and then to the lower energy region, indicating that the concentration of Ti might cause the optical band gap broadening or narrowing. In electrical measurement, the resistivity of a single ZnO nanowire decreases from 0.122Ωcm to 0.035Ωcm because of Ti doping and is 71.3% smaller than the resistivity of undoped ZnO nanowire. At the same time, the piezoelectric effect causes the resistivity of the ZnO nanowire increased when bending. Doping also improve the property of the field emission.

並列關鍵字

Titanium-doped Zinc oxide ； Metal Vapor Vacuum Arc ； Cathodoluminescence ； Resistivity ； Field emission

參考文獻

[1] B. Meyer and Dominik Marx, “Density-functional study of thestructure and stability of ZnO surfaces”, Phys. Rev. B, 67(2003)

[3] Z. Fan, J.G. Lu , “Zinc Oxide Nanostructures: Synthesis and Properties”, J. Nanosci. Nanotechnol., 5, p.1561(2005)

[5] W. S. Hu, Z. G. Liu, R. X. Wu, Y.-F. Chen, W. Ji, T. Yu, and D. Feng “Preparation of piezoelectric-coefficient modulated multilayer film ZnO/Al2O3 and its ultrahigh frequency resonance”, Appl. Phys. Lett. 71, p.548 (1997)

[7] D. R. Vij and N. Singh, "Luminescence and Related Preperties of Ⅱ-Ⅵ Semiconductors" , Nova Science Publishers, N.Y.(1998)

[8] X. T. Zhang,Y. C. Liu,Z. Z. Zhi,J. Y. Zhang, Y. M. Lu, D. Z. Shen, and X. G.Kong, "Temperature Dependence of Excitonic Luminescence from Nanocrystalline ZnO Films", J. of Luminescence, 99, p.149 (2002)