利用鎳鉻合金催化劑合成自動對準單壁奈米碳管場效電晶體

Ni-Cr Alloy to Enhance Single-walled Carbon Nanotube for Self-aligned Field-effect Transistor Application

楊宗曄(Tsung-Yeh Yang)

指導教授 ： 游萃蓉

國立清華大學/工學院/材料科學工程學系/碩士(2006年)

https://doi.org/10.6843/NTHU.2006.00421

摘要

本研究乃利用鎳鉻合金作為成長單壁奈米碳管的催化劑，並合成自組裝單壁奈米碳管場效電晶體。實驗方法為先以電子槍真空蒸鍍系統依序沉積鈦、鉻、鎳、鈦薄膜於已有氧化物層之n+型矽基板(SiO2/n+-Si)上。接著以微影製程及濕式化學蝕刻產生圖形。之後將薄膜置於爐管中升溫至攝氏900度，使鎳擴散至鉻中形成鎳鉻合金並產生鎳奈米顆粒，再使用熱裂解化學氣相沉積法以乙炔作為碳源氣體，氬氣與氫氣的混合氣體為攜帶氣體，合成出均勻性極高的單壁奈米碳管。
以鎳鉻合金為催化劑合成單壁奈米碳管組成自組裝場效電晶體，合成出來的單壁奈米碳管在已定義的兩金屬線中間，兩金屬線分別做為場效電晶體之源極與汲極。n+型矽基板作為閘極，金屬線最小線寬為2微米。實驗結果顯示合成的單壁奈米碳管直徑為1.1至1.9奈米，平均直徑為1.4奈米，且擁有半導體性質，奈米碳管元件亦表現出場效電晶體特性。以鎳鉻合金為催化劑成長的單壁奈米碳管均勻性相較於只用鎳催化劑成長奈米碳管時較高，在本實驗中單壁碳管的均勻性愈高表示在合成出來的碳管中為單壁碳管的比例愈高。

關鍵字

奈米碳管 ； 場效電晶體 ； 合金 ； 催化劑

並列摘要

In this work, self-assembled carbon nanotubes field effect transistors (CNT-FET) with semiconducting single-walled carbon nanotubes (SWNTs) as the channel were synthesized using Ni-Cr alloy as the catalysts. The Ti、Cr、Ni、Ti were deposited sequentially without breaking the vacuum to form Ti/Ni/Cr/Ti multi-layer stack on heavily doped n+ silicon wafer with 100 nm SiO2 layer on top by an E-gun system. After the deposition, thin films were patterned using lithography process and wet chemical etching. While the patterned multi-layer films were heated to the process temperature, of 900℃, Ni diffused into Cr and formed Ni-Cr alloy from Ti/Ni/Cr/Ti film at high temperature. Therefore Ni nano-particles were precipitated from Cr matrix. Single-walled carbon nanotubes were synthesized between two pre-defined Ti/Ni/Cr/Ti metal lines by means of thermal chemical vapor deposition (CVD) at 900℃ for 10 min. The C2H2 was used as reactant gas and the mixture of Ar and H2 was used as a carrier gas.
The SWNTs were synthesized between two pre-defined Ti/Ni/Cr/Ti metal lines, which were used as source and drain in CNT-FET and the heavily doped n+ silicon wafer was used as a back-gate electrode. The spacing between two metal lines in the CNT-FETs was 2-10 μm. The SWNTs synthesized between two Ti/Ni/Cr/Ti metal lines were verified by Raman spectrum and AFM height images. The distribution of CNT diameters was in a range from 1.1 to 1.9 nm, with an average of 1.4 nm. The SWNTs grown using Ni-Cr alloy catalysts exhibit more homogeneous CNTs than those synthesized using Ni catalysts. The semiconducting characteristics of the CNTs using the Ni-Cr alloy catalysts were demonstrated by the transistor characteristics of the CNT-FETs fabricated.

並列關鍵字

carbon nanotubes ； field-effect transistor ； alloy ； catalyst

參考文獻

8 Z. F. Ren, Z. P. Huang, J. W. Xu, J. H. Wang, P. Bush, M. P. Siegal, P. N. Provencio, Science 282, 1105 (1998).

4 L. H. Chan, K. H. Hong, D. Q. Xiao, W. J. Hsieh, S. H. Lai, H. C.Shih, T. C. Lin, F, S. Shieu, K. J. Chen, and H. C. Cheng, Appl. Phys. Lett. 82, 4334 (2003)

28 Young-Soo Han, Jin Koog Shin, and Sung Tae Kim, J. Appl. Phys. 90, 5731 (2001).

1 R. Kubo, J. Phys. Soc. 17, 975 (1962).

2 Ijima S., Nature 354, 56 (1991).