奈米碳管電子元件之製備與應用

Study on Carbon Nanotube Electronic Devices and Their Applications

指導教授 : 黃榮堂 研究生 : 蔡政宏 機電整合研究所 94年


摘要

  本文為奈米碳管電子元件之製備、特性研究與應用。以低溫製備的方式將奈米碳管結合奈米微機電技術製作出奈米碳管電子元件,探討其電子傳遞之物理特性。奈米碳管擁有優良的電子傳遞特性,製作為奈米碳管電子元件後,裸露在外的奈米碳管對於外界環境相當靈敏,非常適合用來做為感測元件;而以低溫的製備方式,能夠將奈米碳管結合至CMOS電路元件,成為一個具有訊號處理之多功能感測器系統。在實驗製作方面,我們以退化型之重掺雜矽基材作為背閘極,基材上方長出100nm之氧化矽絕緣層,配合微影製程定義鈀(Pd)電極於介電層上,再利用介電泳力將奈米碳管接合至電極上方,完成奈米碳管電子元件之製作。本文將商用之單壁奈米碳管粉末溶解於十二烷基硫酸鈉(SDS)有機溶劑中,使之裹上一層有機高分子之膠束,並以物理方法將奈米碳管純化與單根化,在特定的介電泳力參數控制下,成功地製作出擁有場效應特性且電流的ON-OFF達103~104個等級之奈米碳管場效應電晶體與電阻特性之奈米碳管電子元件。在去除裹覆於碳管表面之SDS分子後,能夠降低奈米碳管與接觸金屬之接觸電阻並且減少電子散射的機會,進而改善奈米碳管電子元件特性,提升其電流值約6倍。
  本論文將製作好的奈米碳管場效應電晶體接上不同序列但相同鹼基之單股去氧核醣核酸(ssDNA)分子,藉由奈米碳管與ssDNA分子間的π-π堆疊作用力讓ssDNA上的鹼基接觸到奈米碳管管壁表面,進而造成電晶體之訊號變化分辨出不同的鹼基,以達成初步高速ssDNA定序之目標。此外,在奈米碳管結合ssDNA序列後,此元件亦可作為常溫操作、高靈敏度及快速自我回復之氣體感測器裝置。
 

關鍵詞:奈米碳管、奈米碳管電晶體、低溫製造、CMOS整合元件、基因定序
 

ABSTRACT

 In this thesis, we will discuss the properties, fabrication, and applications of the carbon nanotube electronic devices. Carbon nanotube (CNT) electronic devices were fabricated by low-temperature technique combined with nano-electro-mechanical technologies (NEMS), and the physics of electrical transport will be investigated. Since CNTs have superb mechanical and electrical properties, the fabricated CNT electronic devices with bare CNT channels are very sensitive to the environments which can be used for sensor devices. Otherwise, the low-temperature fabrication can integrate CNTs with CMOS circuitry to disclose a processor-inside sensor system. In the experimental processes, the degenerately p-doped silicon wafers with 100 nm silicon oxide were used as the back gate; palladium (Pd) metal electrodes were formed by photolithography combined with lift-off technique, and finally deposited and aligned CNTs on the predefined electrode pairs to complete devices fabrication by using alternating current dielectrophoresis (AC-DEP). Commercial as-prepared single-walled carbon nanotube (SWCNT) soot was suspended in sodium dodecyl sulfate (SDS) solution and the nanotubes would be coated with SDS micelle, followed by physical purification and debundling treatments, these SWCNTs were manipulated by AC-DEP with experimental control and successfully fabricated carbon nanotube field-effect transistors (CNTFETs) with on/off-state current ratios of 103~104 order and other CNT devices with resistor characteristics. After removing SDS residuals coated on SWCNTs, the formation of an improved metal-CNT contact and reducing the probabilities of carrier scattering resulted in improving performance of the CNT devices and also can have current promoted by 6 factors.
 The three fragmented (20-mer) single-stranded DNA (ssDNA) sequences are composed of identical bases A, T, C respectively which were dropped on the fabricated CNTFETs, and the bases of ssDNA are extended from the backbone and stacked onto the sidewall of SWCNTs via π-π-stacking interaction. These three sequences of captured ssDNA resulted in different changes of electrical transport to the CNTFETs which disclosing an objective of ultra-rapid DNA sequencing. Moreover, CNTFETs decorated with ssDNA can be utilized as a gas sensor with high sensitivity, self-regenerating and working in room- temperature environment.

Key Words: Carbon Nanotubes (CNTs), Carbon Nanotube Field-Effect Transistors (CNTFETs), Low-Temperature Fabrication, Dielectrophoresis (DEP), CMOS Integrated Devices, Ultra-fast DNA Sequencing