以氧化鎂鋅包覆氧化鋅之異質奈米柱結構成長與特性

Synthesis and Characterization of Core-ZnO/Shell-MgZnO Heterostructure Nanorods

李彥佐(Yan-Tsuo Lee)

指導教授 ： 洪魏寬

國立臺北科技大學/電資學院/光電工程系研究所/碩士(2009年)

https://doi.org/10.6841/NTUT.2009.00121

摘要

本研究分為兩個階段製程，第一階段是製作氧化鋅準直奈米柱，先利用PLD在sapphire基板上製作約68nm氧化鋅緩衝層，再利用氣相傳輸法在緩衝層上成長氧化鋅準直奈米柱。並利用SEM觀察表面結構，奈米柱直徑約30±5nm、長約1.3 μm，經XRD觀察成長方向為[0002]，PL強度與結晶品質良好且沒出現DLE。
第二階段是使用氧化鎂(4N8)與氧化鋅(4N5)莫爾比1:10與1:4混合製成氧化鎂鋅靶材，利用PLD鍍氧化鎂鋅以包覆氧化鋅準直奈米柱，使結構成為core-ZnO/shell-MgZnO異質奈米柱。在僅改變雷射發數條件下，利用HRTEM觀察其氧化鎂鋅外殼的厚度變化，殼層的晶格常數介於氧化鎂與氧化鋅之間，驗證出殼層為MgxZn1-xO單晶相。利用PL量測得知氧化鋅(3.298eV)、(1:10)mol% MgxZn1-xO(~3.594eV )與(1:4)mol% MgxZn1-xO( ~3.935eV )。從TEM與PL量測下，根據計算可得到前者成分比為x=0.14而後者為x=0.3。隨著雷射發數的增加，MgxZn1-xO的峰值越趨顯著，故我們可藉由控制殼層厚度達到控制MgxZn1-xO光激發受激輻射的放光強度。

關鍵字

奈米柱 ； 氧化鋅 ； 氧化鎂鋅 ； 殼核異質結構

並列摘要

The formation of heterostrucure in nanorods is essential for their potential applications in nanoelectronic and photonic devices. Here we demonstrate that vertically well-aligned ZnO nanorods and ZnO/MgZnO core-shell nanorods can be successfully synthesized via catalyst-free vapor phase transport combined with pulsed laser deposition (PLD) method.
The thesis consists of two parts. First, the vertically well-aligned ZnO nanorods were grown on a PLD-predeposited ZnO thin film via a simple thermal evaporation and vapor transport process. These ZnO nanorods were quite uniform with a diameter of ~27 nm and length of ~1 μm. Room-temperature photoluminescence spectra of the samples showed only a strong band-edge emission, indicating the high crystalline quality. The well-aligned ZnO nanorods were used as a template for the synthesis of nanorod heterostructures.
In the second part, the vertically well-aligned ZnO/MgZnO core-shell structures of the nanorods were synthesized by PLD of MgZnO onto the ZnO nanorod template. The core-shell heterostructure nanorods were examined by high-resolution transmission electron microscopy measurements. The optical properties of the heterostructure nanorods were analyzed by photoluminescence. The HRTEM images and the corresponding FFT patterns of the nanorods implied that the core/shell is wurtzite structured ZnO/MgZnO with well-defined epitaxial relationship. The positions of the MgxZn1-xO shells, obtained by pused laser ablating MgyZn1-yO targets with y=0.0909 and 0.25, were determained by the Vegard’s law to be x=0.14 and 0.30, respectively. Room-temperature PL spectrum from the ZnO/MgxZn1-xO core-shell nanorods exhibits strong emissions from ZnO core (located at 3.298eV) and MgxZn1-xO shell (located at 3.539eV for x=0.14 and 3.935eV for x=0.30). The core/shell relative emission intensity can be controlled by the shell thickness.

並列關鍵字

nanorods ； ZnO ； MgZnO ； core-shell heterostructure

參考文獻

[46] 謝嘉民、賴一凡、林永昌、枋志堯，「光激發螢光量測的原理、架構及應用」，奈米通訊，第十二卷，第二期，2005，第29-30頁。

[1] Xian-Hua Zhang, Su-Yuan Xie, Zhi-Yuan Jiang, Xuan Zhang, Zhong-Qun Tian, Zhao-Xiong Xie, Rong-Bin Huang, Lan-Sun Zheng, " Catalytic Growth of Zinc Oxide Nanowires by Vapor Transport," Rational Design and Fabrication of ZnO Nanotubes from Nanowire Templates in a Microwave Plasma System," J. Phys. Chem. B, 107, 2003.

[2] Yanhong Tong, Yichun Liu, Changlu Shao, Yuxue Liu, Changshan Xu, Jiying Zhang, Youming Lu, Dezhen Shen, Xiwu Fan, " Growth and Optical Properties of Faceted Hexagonal ZnO Nanotubes," J. Phys. Chem. B, 110, 2006.

[3] Zheng Wei Pan, Zu Rong Dai, Zhong Lin Wang, " Nanobelts of Semiconducting Oxides," Science, 291, 2001.

[5] Aleksandra B. Djurisˇic, Yu Hang Leung, small 2, No.8-9, 2006, pp. 944-961.