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1 J. of the Korean Sensors Society Vol. 18, No. 2 (2009) pp p k ù p p l xá xá ³ Á *Á w * Fabrication of the CNT-FET biosensors with a double-gate structure Byunghyun Cho, Byounghyun Lim, Jang-Kyoo Shin, Sung-Wook Choi*, and Hyang Sook Chun* Abstract In this paper, we present the carbon nanotube field-effect transistor(cnt-fet) with a double-gate structure. A Carbon nanotube film was aligned by the Langmuir-Blodgett technique and SiN x was deposited to protect from water, oxygen, and other contaminants. We measured the electrical characteristics of the proposed device as the function of the V BG, V TG. From this result, we can confirm that proposed device might be employed as a biosensor. Key Words : CNT-FET, biosensor, langmuir-blodgett 1. k ù p w» p w k ù p p l(carbon nanotube field effect transistor, CNT-FET) ƒ y w š [1]. CNT-FET Ÿ (optical measurement),» yw (electrochemistry), (mass measurement) šƒ ƒ v ƒ š xy, y d w, p - y - z p l(metal-oxide-semiconductor field effect transistor, MOSFET) w w p ƒ š [2-8]. k ù p p l k ù p j j (arc discharge), (laser ablation), yw» (chemical vapor deposition, CVD) [9]. p k ù p p l w. k ù p - (Langmuir-Blodgett) w k z g [10]. w, š w»fulw (School of Electrical Engineering and Computer Science, Kyungpook National University) *w t (Korea Food Research Institute) Corresponding author : jkshin@ee.knu.ac.kr (Received : February 17, 2009, Accepted : March 13, 2009) l k ù p yw» w SiN x w [11,12]. SiN x w k ù p w» w back gate x jš ƒw. k ù p p lƒ ƒ mw» w streptavidin biotin w w w» p sƒw. 2. CNT-FET k ù p w w (work function) w w pj (schottky barrier) y w. Px p ƒ k ù p k ù p w ƒ j Au w w w pj w. Fig. 1(a) ƒ k ù p Au š Fig. 1(b) back gate ƒw. Back gate w ƒ { pj š œ(hole) l ù ƒ. top gate t š y w 168

2 p k ù p p l 67 Fig. 2. Cross-sectional view of the CNT-FET biosensor. Fig. 1. Energy band diagram of the CNT-FET with p-type characteristics (a) non bias (b) negative drain bias. w w w pj w š k ù p mw y j. w w w. 3. Fig. 2 CNT-FET ùkü.., SiO 2 /Si»q Ÿ (AZ 5214) w k ù p ƒ e ql w. k ù p - w k z vp v(lift-off)w w œ k ù p e k. x w» w Ÿ (AZ 5214) w ql wš electron beam evaporator w Ti/Au (10 nm/ 100 nm) w z vp v w x Fig. 3. Photograph of the fabricated CNT-FET biosensor. k. z back gate x w» w electron beam evaporator w Ti/Au(10 nm/100 nm) k., š l k ù p yw» w v yw (plasma enhanced chemical vapor deposition, PECVD) w 250 C o SiN x (100 nm) w.»q Ÿ (AZ 5214) w ql wš electron beam evaporator w Ti/ Au(10 nm/100 nm) w z vp vw š w w top gate x w. Fig. 3 ù kü. 20 µm 4. d Fig. 4» p w d l. d w PCB (printed circuit board) w qj (packaging) wz 18«2y,

3 68 xá xá ³Á Á w Fig. 4. System diagram. Fig. 5. Electrical characteristics of the fabricated CNT-FET. (a) I D -V BG characteristics (b) I D -V TG characteristics. w š» Pt» w. k ù p» p w. Fig. 5(a) 1V š k z back Fig. 6. I D -V BG characteristics of the CNT-FET biosensor for biomolecules. gate 5V 5V ƒ g v ùkü. Fig. 5(a) back gate w ƒ w ƒ ƒw. Fig. 5(b) top gate 1V 1V ƒ jš back gate ƒƒ 5V, 0V š 5V ƒƒ y g ùkü. Back gate w ƒwš top gate w ƒ w ƒ ƒw. Fig. 5 mw k ù p p Px p ùký. w» p d. (phosphate buffered saline, PBS, ph 7.4) ü thiol 6-mercaptohexanol w top gate t» (self-assembled monolayer, SAM) x k. z streptavidin j streptavidin» w w š. w biotin wš streptavidin biotin w k. Fig. 6», streptavidin biotin w back gate w y ùkü. d w.» top gate t ww z d w. Fig. 6» ó ew thiol w ƒ ƒw., streptavidin w streptavidin» w streptavidin w ƒ 170 J. Kor. Sensors Soc., Vol. 18, No. 2, 2009

4 p k ù p p l 69. w w ƒ. Acknowledgement w t BK21 w. š x Fig. 7. I D -V TG characteristics of interaction of streptavidin and biotin of the fabricated CNT-FET biosensor. w., biotin(1 mg/ml) w streptavidin biotin w w w w ƒ w y w. Fig. 7 streptavidin biotin w top gate w y ùkü. Back gate 5 V š wš Pt» w top gate 1 V 1V ƒ g d w. Fig. 7 Streptavidin biotin w ƒ w y w. w ƒ ƒ w. 5. p k ù p p l w. w - w k ù p w š l k ù p yw» w SiN x g. SiN x w w back gate ƒw w g p.,» p d w k ù p ƒ Px p ùký y w. š top gate t», streptavidin š biotin š y w g» p d wš ƒƒ ƒ w ƒ yw y w. p, streptavidin biotin w w» p y w ƒ w w y w [1] S. J. Tans, A. R. M. Verschueren and C. Decker, Room-temperature transistor based on a single carbon nanotube, Nature, vol. 393, pp , [2] M. Abe, K. Murata, A. Kojima, Y. Ifuku, M. Shimizu, T. Ataka, and K. Matsumoto, Quantiatatve detection of protein using a top-gate carbon nanotube field effect transistor, J. Phys. Chem. C, vol. 111, pp , [3] D. Piscevic, W. Knoll, and M. J. Tarlov, Surface plasmon mircroscopy of biotin-streptavidin binding reactions on UV-photopatterned alkanthiol selfassembled monolayers, Superamolecular Science, vol 2, pp , [4] H. Zhu, M. Bilgin, R. Bangham, D. Hall, A. Casamayer, P. Bertone, N. Lan, R. Jansen, S. Bidlingmaier, T. Houfek, T. Mitchell, P. Miller, R. A. Dean, M. Gerstein, and M. Snyder, Global analysis of protein activities using proteome chip, Science, vol. 293, pp , [5] C. B. Yuan, A. Chen, P. Kolb, and V. T. Moy, Energy landscape of streptavidin-biotin complexes meaured by atomic force microscopy, Biochemistry, vol. 39, pp , [6], ½, y, ³, ½q,, AFM w p k - p w, wz, 15«, 4y, pp , [7] x, ½, w, ³, s, k - p w w PMOSFETx, w wz ww z, pp , [8] AIST / html [9] P. Ramirez Carbon nanotube for science and technology, Bell Labs Technical Journal 10(3), pp , [10], k ù p Langmuir-Blodgett p sƒ, w w, p. 1, wz 18«2y,

5 70 xá xá ³Á Á w [11] D. Kaminishi, H. Ozaki, Y. Ohno. K. Maehashi, K. Inoue, and K. Matsumoto, Air-stable n-type carbon nanotube field-effect transistor with Si 3 N 4 passivation films fabricated by catalytic chemical vapor deposition, Applied Physics Letters 86, , [12] K. Maehashi, Y. Ohno, K. Inoue, K. Matsumoto, T. Niki and H. Matsumura, Electrical characterization of carbon nanotube field-effcet transistors with SiN x passivation films deposited by catalytic chemical vapor deposition. Applied Physics Letters 92, , 2008U x 2004 w»fulw (œw ) x w w»ful w : FETx x 2008 w»fulw (œw ) x w w»ful w : FETx ³ wz, 3«, 1y, p. 26 x w»fulw 2007 w w» w x w t : t w w 1993 y w t w x w t : t w 172 J. Kor. Sensors Soc., Vol. 18, No. 2, 2009