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Understanding doping effects in biosensing using carbon nanotube network field-effect transistors
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.ORCID iD: 0000-0002-6430-6135
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
2009 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 79, no 155434Article in journal (Refereed) Published
Abstract [en]

Systematic theoretical studies based on a comprehensive heterogeneous stick percolation model are performed to gain insights into the essence of doping effects in electrical sensing of biomolecules, such as proteins and DNA fragments, using carbon nanotube network field-effect transistors (CNNFETs). The present work demonstrates that the electrical response to doping of CNNFETs is primarily caused by conductance change at the electrode-nanotube contacts, in contrast to that in the channel as assumed previously. However, the presence of intertube junctions in the channel could reduce the sensitivity of CNNFET-based biosensors and is partially responsible for the experimentally observed channel-length dependent sensitivity.

Place, publisher, year, edition, pages
2009. Vol. 79, no 155434
Keyword [en]
biosensors, carbon nanotubes, DNA, doping, field effect transistors, molecular biophysics, nanocontacts, nanotube devices, percolation, proteins, thin-film transistors, contact resistance, devices, transition, transport, density, scale
URN: urn:nbn:se:kth:diva-18411DOI: 10.1103/PhysRevB.79.155434ISI: 000265944200123ScopusID: 2-s2.0-66149183139OAI: diva2:336458
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2011-01-12Bibliographically approved
In thesis
1. Ink-jet printing of thin film transistors based on carbon nanotubes
Open this publication in new window or tab >>Ink-jet printing of thin film transistors based on carbon nanotubes
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The outstanding electrical and mechanical properties of single-walled carbon nanotubes (SWCNTs) may offer solutions to realizing high-mobility and high-bendability thin-film transistors (TFTs) for the emerging flexible electronics. This thesis aims to develop low-cost ink-jet printing techniques for high-performance TFTs based on pristine SWCNTs. The main challenge of this work is to suppress the effects of “metallic SWCNT contamination” and improve the device electrical performance. To this end, this thesis entails a balance between experiments and simulations.


First, TFTs with low-density SWCNTs in the channel region are fabricated by utilizing standard silicon technology. Their electrical performance is investigated in terms of throughput, transfer characteristics, dimensional scaling and dependence on electrode metals. The demonstrated insensitivity of electrical performance to the electrode metals lifts constrains on choosing metal inks for ink-jet printing.


Second, Monte Carlo models on the basis of percolation theory have been established, and high-efficiency algorithms have been proposed for investigations of large-size stick systems in order to facilitate studies of TFTs with channel length up to 1000 times that of the SWCNTs. The Monte Carlo simulations have led to fundamental understanding on stick percolation, including high-precision percolation threshold, universal finite-size scaling function, and dependence of critical conductivity exponents on assignment of component resistance. They have further generated understanding of practical issues regarding heterogeneous percolation systems and the doping effects in SWCNT TFTs.


Third, Monte Carlo simulations are conducted to explore new device structures for performance improvement of SWCNT TFTs. In particular, a novel device structure featuring composite SWCNT networks in the channel is predicted by the simulation and subsequently confirmed experimentally by another research group. Through Monte Carlo simulations, the compatibility of previously-proposed long-strip-channel SWCNT TFTs with ink-jet printing has also been demonstrated.


Finally, relatively sophisticated ink-jet printing techniques have been developed for SWCNT TFTs with long-strip channels. This research spans from SWCNT ink formulation to device design and fabrication. SWCNT TFTs are finally ink-jet printed on both silicon wafers and flexible Kapton substrates with fairly high electrical performance.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. xiv, 58 p.
Trita-ICT/MAP AVH, ISSN 1653-7610 ; 2010:08
Single-walled carbon nanotube, thin film transistor, ink-jet printing, Monte Carlo simulation, stick percolation, composite network, flexible electronics
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
urn:nbn:se:kth:diva-24427 (URN)978-91-7415-717-8 (ISBN)
Public defence
2010-09-24, Sal D, KTH Forum, Isafjordsgatan 39, Kista, 13:15 (English)
QC 20100910Available from: 2010-09-10 Created: 2010-09-08 Last updated: 2010-09-10Bibliographically approved

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