背閘極式碳奈米管電晶體之研究

Study of back-gated carbon nanotube transistors

黃承俊(Cheng-Jyun Huang)

指導教授 ： 黃豐元

國立中央大學/工學院/機械工程學系/碩士(2006年)

摘要

本論文製作出背閘極式(back-gated)三極結構碳奈米管場效電晶體(Carbon nanotube field effect transistors, CNT-FETs)。結合半導體製程，以光學微影技術(photolithography)定義出元件圖案，再從元件間隙(gap)中成長橫向碳奈米管作為電晶體的通道(channel)部分。以鎳層(Ni layer)為催化金屬，並利用熱化學氣相沉積系統(Thermal chemical vapor deposition, Thermal CVD)合成碳管。成長溫度為750℃、碳源為甲烷1000 sccm並搭配氫氣 300 sccm、氮氣 200 sccm為載氣，以獲得理想的單根多壁碳奈米管(Multi-walled carbon nanotubes, MWNTs)橋接。
在研究中我們觀察到，當元件的gap越小時，比較容易獲得碳管的橫向橋接；而當氮氣比例增加時，碳管的成長數量會減少，同時經由拉曼(Raman)光譜分析可以發現其石墨化程度會跟著提高。電性量測方面，元件在低溫真空下具有雙極性(ambipolar)的現象；吸附大量水分子後，電性會有明顯的改變，去除水分子後又恢復；而經過真空熱退火400℃ 1小時，元件的電阻值可以從10.10 MΩ下降至1.79 MΩ且其轉移電導(transconductance)有下降的趨勢。

關鍵字

碳奈米管 ； 電晶體 ； 低溫量測 ； 退火

並列摘要

In this paper, we fabricated the back-gated carbon nanotube field effect transistors(CNT-FETs). Combining with the semiconductor fabrication techniques, we defined the pattern of devices by photolithography, and then we in-situ grew lateral CNTs as channel of transistors. Nickel layer was used to be the catalyst and we synthesized the multi-walled carbon nanotubes(MWNTs) by thermal chemical vapor deposition(Thermal CVD). The growth temperature was 750℃, methane 1000 sccm as carbon source and H2 300 sccm、N2 200 sccm as carrier gas to obtain ideal individual CNTs bridge.
We found that in the smaller gap of devices, the CNTs bridge were obtained more easily. As N2 flow ratio increased, the quantity of CNTs would reduce and simultaneously by the Raman spectra analysis, we observed that the degree of graphitization of CNTs would raise. In the aspect of electricity measurement, the ambipolar phenomenon of the devices at low temperature in vacuum were discovered. Furthermore, absorbing a lot of water molecules, the electronic properties of devices would alter, but after removing water molecules, they restored. It appeared, after annealing treatment, the resistance of CNT-FETs would reduce from 10.10 MΩ to 1.79 MΩ and the transconductance would reduce, too.

並列關鍵字

annealing ； low temperature measurement ； transistor ； carbon nanotube

參考文獻

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