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Blom, Tobias
Publications (10 of 48) Show all publications
Jafri, S. H., Löfås, H., Blom, T., Wallner, A., Grigoriev, A., Ahuja, R., . . . Leifer, K. (2015). Nano-fabrication of molecular electronic junctions by targeted modification of metal-molecule bonds. Scientific Reports, 5, Article ID 14431.
Open this publication in new window or tab >>Nano-fabrication of molecular electronic junctions by targeted modification of metal-molecule bonds
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2015 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 14431Article in journal (Refereed) Published
Abstract [en]

Reproducibility, stability and the coupling between electrical and molecular properties are central challenges in the field of molecular electronics. The field not only needs devices that fulfill these criteria but they also need to be up-scalable to application size. In this work, few-molecule based electronics devices with reproducible electrical characteristics are demonstrated. Our previously reported 5 nm gold nanoparticles (AuNP) coated with omega-triphenylmethyl (trityl) protected 1,8-octanedithiol molecules are trapped in between sub-20 nm gap spacing gold nanoelectrodes forming AuNP-molecule network. When the trityl groups are removed, reproducible devices and stable Au-thiol junctions are established on both ends of the alkane segment. The resistance of more than 50 devices is reduced by orders of magnitude as well as a reduction of the spread in the resistance histogram is observed. By density functional theory calculations the orders of magnitude decrease in resistance can be explained and supported by TEM observations thus indicating that the resistance changes and strongly improved resistance spread are related to the establishment of reproducible and stable metal-molecule bonds. The same experimental sequence is carried out using 1,6-hexanedithiol functionalized AuNPs. The average resistances as a function of molecular length, demonstrated herein, are comparable to the one found in single molecule devices.

National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:uu:diva-264841 (URN)10.1038/srep14431 (DOI)000361596000001 ()26395225 (PubMedID)
Funder
Swedish Research CouncilKnut and Alice Wallenberg FoundationCarl Tryggers foundation Swedish Energy AgencySwedish Foundation for Strategic Research
Available from: 2015-10-19 Created: 2015-10-19 Last updated: 2019-04-24Bibliographically approved
Jafri, S. H., Blom, T., Wallner, A., Ottosson, H. & Leifer, K. (2014). Stability optimisation of molecular electronic devices based on nanoelectrode-nanoparticle bridge platform in air and different storage liquids. Journal of nanoparticle research, 16(12), 2811
Open this publication in new window or tab >>Stability optimisation of molecular electronic devices based on nanoelectrode-nanoparticle bridge platform in air and different storage liquids
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2014 (English)In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 16, no 12, p. 2811-Article in journal (Refereed) Published
Abstract [en]

The long-term stability of metal nanoparticle-molecule junctions in molecular electronic devices based on nanoelectrodes (NEL) is a major challenge in the effort to bring related molecular electronic devices to application. To optimize the reproducibility of molecular electronic nanodevices, the time-dependent modification of such junctions as exposed to different media needs to be known. Here, we have studied (1) the stability of Au-NEL and (2) the electrical stability of molecule-Au nanoparticle (AuNP) junctions themselves with the molecule being 1,8-octanedithiol (ODT). Both the NELs only and the junctions were exposed to air and liquids such as deionized water, tetrahydrofuran, toluene and tetramethylethylenediamine (TMEDA) over a period of 1 month. The nanogaps remained stable in width when stored in either deionized water or toluene, whereas the current through 1,8-octanedithiol-NP junctions remained most stable when stored in TMEDA as compared to other solvents. Although it is difficult to follow the chemical processes in such devices in the 10-nm range with analytical methods, the behavior can be interpreted from known interactions of solvent molecules with electrodes and ODT.

Keywords
Nanoelectronics, Nanoelectrodes, Molecular electronics, Shelf-life, Storage conditions
National Category
Chemical Sciences Nano Technology
Identifiers
urn:nbn:se:uu:diva-242016 (URN)10.1007/s11051-014-2811-6 (DOI)000346697000067 ()
Available from: 2015-01-20 Created: 2015-01-20 Last updated: 2019-04-24Bibliographically approved
Jafri, S. M., Blom, T., Wallner, A., Ottosson, H. & Leifer, K. (2014). Stability optimisation of molecular electronic devices based on nanoelectrode–nanoparticle bridge platform in air and different storage liquids. Journal of nanoparticle research, 16(12), 1-11
Open this publication in new window or tab >>Stability optimisation of molecular electronic devices based on nanoelectrode–nanoparticle bridge platform in air and different storage liquids
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2014 (English)In: Journal of nanoparticle research, Vol. 16, no 12, p. 1-11Article in journal (Refereed) Published
National Category
Nano Technology
Identifiers
urn:nbn:se:uu:diva-259959 (URN)
Available from: 2015-08-13 Created: 2015-08-13 Last updated: 2019-04-24
Leifer, K., Li, H., Jafri, H., Blom, T., Daukiya, L., Vonau, F. & Simon, L. (2014). Structural, electrical and sensing properties of defected graphene. In: Structural, electrical and sensing properties of defected graphene: . Paper presented at 7th international conference on molecular electronic, Strasbourg, August 25-29, 2014.
Open this publication in new window or tab >>Structural, electrical and sensing properties of defected graphene
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2014 (English)In: Structural, electrical and sensing properties of defected graphene, 2014Conference paper, Poster (with or without abstract) (Other academic) [Artistic work]
National Category
Materials Engineering Nano Technology Physical Sciences
Identifiers
urn:nbn:se:uu:diva-244695 (URN)
Conference
7th international conference on molecular electronic, Strasbourg, August 25-29, 2014
Available from: 2015-02-19 Created: 2015-02-19 Last updated: 2019-04-24
Leifer, K., Li, H., Jafri, S. M., Blom, T., Daukiya, L., Vonau, F. & Simon, L. (2014). Structural, electrical and sensing properties of defected graphene. In: : . Paper presented at 7th international conference on molecular electronic, Strasbourg, August 25-29, 2014.
Open this publication in new window or tab >>Structural, electrical and sensing properties of defected graphene
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2014 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-259962 (URN)
Conference
7th international conference on molecular electronic, Strasbourg, August 25-29, 2014
Available from: 2015-08-13 Created: 2015-08-13 Last updated: 2019-04-24
Jafri, H. M., Löfås, H., Jonas, F., Blom, T., Grigoriev, A., Wallner, A., . . . Leifer, K. (2013). Identification of vibrational signatures from short chains of interlinked molecule-nanoparticle junctions obtained by inelastic electron tunnelling spectroscopy. Nanoscale, 5(11), 4673-4677
Open this publication in new window or tab >>Identification of vibrational signatures from short chains of interlinked molecule-nanoparticle junctions obtained by inelastic electron tunnelling spectroscopy
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2013 (English)In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 5, no 11, p. 4673-4677Article in journal (Refereed) Published
Abstract [en]

Short chains containing a series of metal- molecule-nanoparticle nanojunctions are a nano-materials system with the potential to give electrical signatures close to those from single molecule experiments while enabling to build portable devices on a chip. Inelastic electron tunnelling spectroscopy (IETS) measurements provide one of the most characteristic electrical signals of single and few molecules. In interlinked molecule-nanoparticle (NP) chains containing of typically 5-7 molecules in a chain, the spectrum is expected to be a superposition of the vibrational signature of individual molecules. We have established a stable and reproducible molecule-AuNP multi-junction by placing few 1,8-octanedithiol (ODT) molecules into a versatile and portable nanoparticle-nanoelectrode platform and measured for the first time vibrational molecular signatures complex and coupled few-molecule-NP junctions. From quantum transport calculations, we model the IETS spectra and identify vibrational modes as well as the number of molecules contributing to the electron transport in the measured spectra.

National Category
Condensed Matter Physics Engineering and Technology
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-198704 (URN)10.1039/C3NR00505D (DOI)000319008700011 ()
Projects
KoF U3MEC
Available from: 2013-04-23 Created: 2013-04-23 Last updated: 2019-04-24Bibliographically approved
Leifer, K., Jafri, H., Löfås, H., Blom, T., Hayat, A., Fransson, J., . . . Ahuja, R. (2012). A 10-nm sized molecular electronics platform for applied and fundamental molecular property measurements. In: Proceedings of Elecmol conference, Grenoble, 2012.: . Paper presented at Proceedings of Elecmol conference, Grenoble, 2012.. Grenoble
Open this publication in new window or tab >>A 10-nm sized molecular electronics platform for applied and fundamental molecular property measurements
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2012 (English)In: Proceedings of Elecmol conference, Grenoble, 2012., Grenoble, 2012Conference paper, Oral presentation with published abstract (Refereed)
Place, publisher, year, edition, pages
Grenoble: , 2012
National Category
Materials Engineering
Identifiers
urn:nbn:se:uu:diva-223195 (URN)
Conference
Proceedings of Elecmol conference, Grenoble, 2012.
Available from: 2014-04-16 Created: 2014-04-16 Last updated: 2019-04-24
Hajati, Y., Blom, T., Jafri, S. H., Haldar, S., Bhandary, S., Shoushtari, M. Z., . . . Leifer, K. (2012). Improved gas sensing activity in structurally defected bilayer graphene. Nanotechnology, 23(50), 50550
Open this publication in new window or tab >>Improved gas sensing activity in structurally defected bilayer graphene
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2012 (English)In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 23, no 50, p. 50550-Article in journal (Refereed) Published
Abstract [en]

Graphene is a two-dimensional material with a capability of gas sensing, which is here shown to be drastically improved by inducing gentle disorder in the lattice. We report that by using a focused ion beam technique, controlled disorder can be introduced into the graphene structure through Ga + ion irradiation. This disorder leads to an increase in the electrical response of graphene to NO 2 gas molecules by a factor of three in an ambient environment (air). Ab initio density functional calculations indicate that NO 2 molecules bind strongly to Stone–Wales defects, where they modify electronic states close to the Fermi level, which in turn influence the transport properties. The demonstrated gas sensor, utilizing structurally defected graphene, shows faster response, higher conductivity changes and thus higher sensitivity to NO 2 as compared to pristine graphene.

National Category
Atom and Molecular Physics and Optics Engineering and Technology
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-186253 (URN)10.1088/0957-4484/23/50/505501 (DOI)000311855300014 ()
Available from: 2012-11-28 Created: 2012-11-28 Last updated: 2019-04-24
Jafri, S. H., Blom, T., Welch, K. & Leifer, K. (2012). Nanoparticle Bridges for Studying Electrical Properties of Organic Molecules. In: Soloviev, M. (Ed.), Nanoparticles in Biology and Medicine: (pp. 535-546). Springer Publishing Company
Open this publication in new window or tab >>Nanoparticle Bridges for Studying Electrical Properties of Organic Molecules
2012 (English)In: Nanoparticles in Biology and Medicine: / [ed] Soloviev, M., Springer Publishing Company, 2012, p. 535-546Chapter in book (Refereed)
Place, publisher, year, edition, pages
Springer Publishing Company, 2012
Series
Methods in Molecular Biology, ISSN 1064-3745 ; 906
National Category
Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials; Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-190632 (URN)10.1007/978-1-61779-953-2_43 (DOI)978-1-61779-952-5 (ISBN)
Available from: 2013-01-08 Created: 2013-01-08 Last updated: 2019-04-24Bibliographically approved
Blom, T., Jafri, H., Widenkvist, E., Jansson, U., Grennberg, H., Quinlan, R. A., . . . Leifer, K. (2011). An In-Situ Prepared Nano-Manipulator Tip for Electrical Characterization of Free Standing Graphene Like Sheets Inside a Focused Ion Beam/Scanning Electron Microscope. Journal of Nanoelectronics and Optoelectronics, 6(2), 162-168
Open this publication in new window or tab >>An In-Situ Prepared Nano-Manipulator Tip for Electrical Characterization of Free Standing Graphene Like Sheets Inside a Focused Ion Beam/Scanning Electron Microscope
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2011 (English)In: Journal of Nanoelectronics and Optoelectronics, ISSN 1555-130X, E-ISSN 1555-1318, Vol. 6, no 2, p. 162-168Article in journal (Refereed) Published
Abstract [en]

Although contacting and moving atoms has been demonstrated using probe techniques, for many nano-objects, a fast and reproducible nano-probe technique is needed to acquire a large number of electrical measurements on nano-objects that are often similar but not the identical. Nano-manipulators have become a common tool in many scanning electron microscopes (SEM) and focussed ion beam devices (FIB). They can be rapidly and reproducibly moved from one nano-object to another. In this work we present a procedure to obtain reproducible electrical measurements of nano- to micron-sized objects by using a sharp, tungsten tip with well defined surface properties. The tip is a part of a manipulator and is sharpened in-situ by using the gallium ion beam inside a focused ion beam/scanning electron microscope (FIB/SEM). The contact resistance between a Au surface and the tip is 70 kΩ before the sharpening procedure and 10 Ω after sharpening. The leakage current of the total set-up of 10pA makes it possible to measure currents through a variety of nano-objects. This measurement technique is applied to measure the resistance of as grown, water treated and two HCl treated carbon nanosheets (CNS). These CNS vary in size and morphology. Using this nano-contacting set-up, we could obtain measurements of more than 400 different CNS. The obtained histograms allow us to observe a clear decrease of the resistance between original and 3 hour acid treated CNSs. We observe that longer periods of exposure of the CNS to the HCl do not further modify the resistance.

Place, publisher, year, edition, pages
American Scientific, 2011
Keywords
Focused ion beam, FIB, electrical characterization, Nano-sized object
National Category
Nano Technology Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Materials Analysis; Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-122954 (URN)10.1166/jno.2011.1154 (DOI)000296210100013 ()
Available from: 2010-04-21 Created: 2010-04-21 Last updated: 2019-04-24Bibliographically approved
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