Dependence of sensitivity of biosensor for carbon nanotube field-effect transistor with top-gate structures

作者：Abe Masuhiro^*; Murata Katsuyuki; Matsumoto Kazuhiko

来源：Journal of Applied Physics, 2010, 107(8): 084504.

DOI：10.1063/1.3298904

In this study, we used biosensors that employ a top-gate-type carbon nanotube field-effect transistor (CNT-FET) for detecting target proteins in a solution. The dependence of the sensitivity of the biosensor on structural characteristics of the top gate, such as the thicknesses of its insulator and electrode and the relative permittivity of the insulator, was examined by simulations and by experiment which change the thickness of the insulator. Results of calculations performed by the finite element method showed that a thin insulator with a relative permittivity greater than 20 would lead to high sensitivity of the CNT-FET biosensor. Experimental investigation supported this result. The transconductance of a CNT-FET with a 20-nm-thick insulating layer was found to be approximately six times higher than that with 50-nm-thick and 80-nm-thick insulating layers. Moreover, the sensitivity of the CNT-FET biosensor with the 20-nm-thick insulating layer was also higher than that of a CNT-FET with a thicker insulating layer. By the experimental measurements, the influence of insulator thickness on the sensitivity of the biosensor was elucidated for the first time.

• 出版日期2010-4-15