Julich Aachen Research Alliance Fundamentals of Future Information Technology JARA FIT

Germany

Julich Aachen Research Alliance Fundamentals of Future Information Technology JARA FIT

Germany

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Demarina N.V.,Jülich Research Center | Demarina N.V.,Julich Aachen Research Alliance Fundamentals of Future Information Technology JARA FIT | Grutzmacher D.A.,Jülich Research Center | Grutzmacher D.A.,Julich Aachen Research Alliance Fundamentals of Future Information Technology JARA FIT
Applied Physics Letters | Year: 2011

We report a theoretical study of the hole density and the low-field mobility in modulation p-doped rolled-up Si/SiGe heterostructures. Solving coupled Poisson and Schrödinger equations, we show that the total hole density is strongly affected by charged surface states and can reach value of 1011 cm-2 for available doping level at room and low temperature. The simulation of the hole transport along the structure axis based on a Monte Carlo method reveals that the interface roughness scattering is a main mechanism limiting the mobility magnitude, which reaches the value of 104 cm2 /V s. © 2011 American Institute of Physics.


Koposova E.,Saint Petersburg State University | Kisner A.,Jülich Research Center | Kisner A.,Julich Aachen Research Alliance Fundamentals of Future Information Technology JARA FIT | Shumilova G.,Saint Petersburg State University | And 5 more authors.
Journal of Physical Chemistry C | Year: 2013

Methods to prepare ultrathin gold nanowires and monodisperse nanoparticles based on the intrinsic property of gold(I) ions to form aurophilic interactions stabilized by oleylamine and long-chain alkylamine have been widely explored. Due to the low thermodynamic stability of the high aspect ratio nanostructures, their conjugation and assembly into functional nanosystems have not been explored so far. One of the reasons for this is that the surface of the nanostructures is insulated by stabilization compounds, which preserve the integrity of the nanostructures but at the same time form an insulating barrier in electronic and electrochemical systems in contact areas and for the charge transfer reactions. Conjugation of a metalloprotein cytochrome c (Cyt c) with oleylamine-stabilized gold ultrathin nanowires and nanoparticles into a bioelectrochemically active nanoarchitecture is presented here for the first time. Methods of preparing and assembling the ultrathin nanowires and nanoparticles on the thin-film gold electrodes are shown. Thermodynamic and kinetic parameters were obtained for the direct electron transfer reaction of cyt c on these surfaces. Nanowires are responsible for an approximately -20 mV shift in the redox potential of the ferri/ferro-cyt c couple relative to a thin-film gold electrode. © 2013 American Chemical Society.


Koposova E.,Saint Petersburg State University | Liu X.,Jülich Research Center | Liu X.,Julich Aachen Research Alliance Fundamentals of Future Information Technology JARA FIT | Kisner A.,Jülich Research Center | And 8 more authors.
Biosensors and Bioelectronics | Year: 2014

This paper describes ultrathin gold nanowires (NWs) and nanoparticles (NPs) prepared by oleylamine (OA) synthesis and their assembly with horseradish peroxidase enzyme (HRP) for bioelectrochemical sensing of hydrogen peroxide for the first time. The immobilization of oxidoreductase enzyme HRP on the electrodes modified with OA gold nanostructures (OANSs) is discussed. The HRP-sensor characteristics, namely sensitivity, working concentration range, sensor-to-sensor and measurement-to-measurement reproducibility as well as long-term stability, are improved significantly compared to the planar thin-film sensors by using OANSs. The thin-film gold electrodes modified with OANWs and OANPs exhibit a catalytic activity towards oxidation of hydrogen peroxide with a working concentration range from 20μM to 500μM, a sensitivity of 0.031AM-1cm-2 (RSD 0.046) and 0.027AM-1cm-2 (RSD 0.045), and a detection limit of 5μM and 8μM, respectively (RSD near the detection limits was 9-12%). Our study shows that ultrathin gold nanowires and nanoparticles prepared by oleylamine synthesis are prospective materials to assemble biomolecules into functional nanoarchitectures for enzyme-based bioelectrochemical sensors, metalloprotein bioelectronics, and energy research. © 2014 Elsevier B.V.


Mashoff T.,RWTH Aachen | Mashoff T.,Julich Aachen Research Alliance Fundamentals of Future Information Technology JARA FIT | Pratzer M.,RWTH Aachen | Pratzer M.,Julich Aachen Research Alliance Fundamentals of Future Information Technology JARA FIT | And 9 more authors.
Nano Letters | Year: 2010

The truly two-dimensional material graphene is an ideal candidate for nanoelectromechanics due to its large strength and mobility. Here we show that graphene flakes provide natural nanomembranes of diameter down to 3 nm within its intrinsic rippling. The membranes can be lifted either reversibly or hysteretically by the tip of a scanning tunneling microscope. The clampedmembrane model including van-der-Waals and dielectric forces explains the results quantitatively. AC-fields oscillate the membranes, which might lead to a completely novel approach to controlled quantized oscillations or single atom mass detection. © 2010 American Chemical Society.

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