成果報告書詳細
管理番号20100000001256
タイトル*平成21年度中間年報 ナノエレクトロニクス半導体新材料・新構造ナノ電子デバイス技術開発 カーボンナノチューブトランジスタ技術の研究開発
公開日2011/1/8
報告書年度2009 - 2009
委託先名国立大学法人名古屋大学
プロジェクト番号P09002
部署名電子・情報技術開発部
和文要約和文要約等以下本編抜粋:1.研究開発の内容及び成果等
(1)cNTデバイス作製技術の研究開発HfO2ゲート酸化膜を用いるとp型FETがn型FETに変化する原因について検討し、HfO2/SiO2界面に固定電荷が導入されるため(図1)であることを明らかにした。得られたnチャネルCNT・FETのドレイン電流は10mA/LLm(図2)とITRSの2020年の目標をクリアしており(数倍)、特性は世界トップクラスである。on/off比、S値も106,95mV/decと良好であり、また100日間n型特性を保持することを確認した。
英文要約Title: Development of Nanoelectronic Device Technology Project. Research and development of carbon nanotube transistor technology (FY2009-FY2010) FY2009 Annual Report
It has been shown that the conduction type of the CNT-FET was dependent on the material used for the gate insulator, n type for the HfO2 and p type for the Al2O3 gate insulators. The difference was ascribed to the difference in the density of the positive charge introduced at the gate insulator/SiO2 interface. We have succeeded in implementing C-MOS inverter using this technique. Current gain cutoff frequency of the mushroom-type tope-gate CNT-FET was 4 GHz. In order to improve the device performance, we studied the technique to grow the high-density horizontally aligned CNTs on the quartz substrate and succeeded in obtaining 23 CNTs/um by introducing small amount of ethanol during the reduction process. Thermal CVD technique was developed for the preferential growth of high-quality semi-conductor CNTs. By using the high-vacuum apparatus, SWNTs were grown with low pressure ethanol and at low temperatures. The effect of very small amount of impurity in the carbon source gas was found to be critical. For the growth of high density SWNT arrays, we studied the growth on sapphire substrates. Effects of the catalyst film thickness and the metal composition were studied to increase the SWNT density. We obtained the SWNT densities of ~5 tubes/ um for Fe film and ~10 for the binary catalysts on average. We created trench structures on a SiO2/Si substrate by lithography and etching, and first demonstrated a horizontal SWNT alignment. By applying both the intermittent bias application and sampling detection methods on Kelvin probe force microscopy, we have observed different inhomogeneity in potential distribution among some CNTs, which may be related with the existence of the defects in CNTs. On the other hand, the current-induced magnetic fields around CNT channels in FET were observed by magnetic force microscopy with a special cantilever having a modified shape, and we found the difference of the threshold gate bias and the transconductance among different CNT channels. Recently, further improvement of the sensitivity is aimed through re-designing of the cantilever shape.
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