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Nanowire/Graphene FETs

Low dimension devices allow pushing detection limits and provide enhanced sensitivity to the surface potential changes due to high surface-to-volume ratio that make them promising  for a number of biosensing applications. Among these devices, nanowire (NWs) field-effect transistors (FETs) are emerging as key structures of modern nanoelectronics and bioelectronics. These devices have attracted attention as excellent candidates for the development of new label-free, low-noise, high-speed and ultra-sensitive biosensors.  The high aspect ratio and nanoscale diameter allow improved interfacing to living cells and provide an instrument for highly sensitive and selective analysis of biological objects.

Our strategy

  • To develop field effect transistors (FETs) with new functionality, which provides fast and sensitive signal transduction from biomaterials
  • To focus on solutions for realizing a next generation diagnostic platform.
  • To strengthen the competitive position through innovation technology
  •  To develop new detection approaches utilizing new parameters and quantum phenomena

 Our research goals supported by RWTH innovation award 2016 [1]  include:

  • Design and fabrication of high-performance and low-noise FETs with different sizes/geometries (Fig.1).
  • Development of NW FETs with new detection principles, which provides fast and sensitive biosignal recording
  • Implementation of novel thin functional layers for high-sensitive and selective detection of low concentration analyte (e.g. Troponin, CRP) or action potentials of electroactive cells (e.g. neurons,  HL1 cardiac cells)   
  • Improvement of stability and reliability of  NW FETs for biosensor applications
  • Discovery and application of novel approaches and techniques for sensitivity enhancement and noise level optimization.

Nanowires/Graphene(Left) SEM image of single silicon nanowire FET; (Right) Schematic of liquid-gated FET biosensor

Noise spectroscopy of NW field effect transistors (FETs) allows to study transport phenomena. Our noise measurement set-up developed in-house enables us to find optimal regimes of nanochannel devices for biosensor applications. Our work includes several directions. Investigation of transport phenomena in NW FETs in order to utilize their full potential as biosensors. Improved sensitivity may be achieved by utilization of gate coupling effect (Fig.2a) and optimization of signal-to-noise ratio due to switching of scattering mechanisms [2-4]. Investigation of the conducting channel modulation effect caused by a single trap in the gate dielectric is also in focus of our studies for developing novel sensing approaches based on the single trap phenomena [5-9].

Nanowires/Graphene 2(Left)Transconductance of n+-p-n+ Si NW FETs measured at drain-souce voltage of 1V and plotted in a color map as a fucntion of liquid gate and back gate voltage; Red corresponds to the maximum transconductance; (Right) Image of neuronal cells (green) cultured on Si NW FET structure.


During last decade ultrathin metal nanowire structures attracted considerable attention of researchers. Ultrathin metal nanowires showed properties extremely sensitive to the surface charges, induced by the influence of molecular layers, assembled onto their surface [10]. The dynamic processes of charge transport in such systems can be analyzed using noise spectroscopy. The influence of assembled molecular layers demonstrates a response in the low-frequency noise spectra of ultrathin gold nanowires (Au NWs, ~2 nm in diameter) [11,12]. This reflect applicability of noise spectroscopy as the powerful technique to study molecular interfaces.

In the framework of the BMBF DIRTDANAT and Nano- and Biosystems Electromagnetic Sensing Technology (NANOBEST) projects, we are working on the exploitation of hot carrier effects and quantum phenomena in nanowire  and nanotube transistor structures [13] to explore innovative applications in quantum information processing and nanotechnology (Fig.3).  The main challenge is to push the sensitivity of biosensors down to the lowest analyte concentration.

Nanowires/Graphene 3(Left) A schematic cross section of the heterostructure with parallel NWs; (Right) Distribution of electrostatic potential energy around NWs at z=0 in units of kBT calculated at T = 300 K for the sample with W = 360 nm. Zero value x=0 level corresponds to the middle of the NWs.

In addition, a number of novel possibilities can be realized by carbon-based field-effect transistors due to effective tuning of the channel conductivity by gate electrodes and utilization of quantum effects at the nanoscale. Carbon-based nanotube (CNT) transistors are considered to be the next generation of ultra-sensitive and ultra-fast biosensing systems. We are working on development of individual CNT FETs and study their noise properties in several gate configurations with utilization of different dielectric layers and report promising results for ultra-fast biosensing applications [14].  The graphene field-effect transistors (GFETs) fabricated on a novel substrates, including flexible and biocompatible ones open new directions for very small biological signal detections [15,16].

Additional Information

Contact:

Priv.-Doc. Dr. Svetlana Vitusevich

Tel.:  +49-2461-61-2345
e-mail: s.vitusevich@fz-juelich.de

More Information

References/Publications:

[1] RWTH innovation award 2016

[2] S. Pud et al. Nano Letters.14,578-584 (2014)

[3] Excellent doctoral dissertation award 2016: Sergii Pud “Silicon nanowire Structures for Neuronal Cell Interfacing”, Copyright  Forschungszentrum Juelich 2015.

[4] F. Gasparyan et al. Journ Appl.Phys.  120 (6), 064902-1-8 (2016).

[5] S. Pud et al. Journ. of Appl. Phys. 115, 233705-1-11 (2014)

[6] J. Li et al. Nanotechnology. 25,275302-1-7 (2014)

[7] J. Li  et al. Nano Letters. 14,3504-3509 (2014)

[8] F. Gasparyan et al. Journ.Appl.Phys. 117,174506-1-5 (2015)

[9] I.Zadorozhnyi et al. MRS advances. IP. 213.168.117.57, Cambridge Journals, Materials Research Society, doi:10.1557/adv.2016.347, 6 pages (2016).

[10] S. Pud et al.,  Small, 9,  846–852 (2013).

[11] V. Handziuk et al. J. Stat. Mech. Theory Exp., 5, 054023-1-8  (2016).

[12] Best student poster award 2016: Volodymyr Handziuk “Effect of molecular layers on charge transport in nanowires”

[13] B. Danilchenko et al. Appl .Phys.Lett. 104, 072105-1-5 (2014).

[14] V.Sydoruk et al. Nanotechnology 25, 035703-1-10 (2014).

[15] A.  Babichev et al. Nanotechnology 25,335707 -1-11 (2014).

[16] D.Kireev et al. Graphene field effect transistors for in‐vitro and ex‐vivo Recordings, submitted to “ IEEE transactions of Nanotechnology” (2016)

Patents:

S.Vitusevich et al. „Device and method for measuring snall voltages and potentials on a biological, chemical or other sample“ DE 10 2013 018 850 A1, followed by US Application No. 15/033,235 filed April 29, 2016


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