For Online registration on NanoIsrael 2019



Michael Greenman1, Nir Tessler2

1 Electrical Engineering ; Technion
2 Nanoelectronics Center; Department of Electrical Engineering

Vertical organic field effect transistor is a growing research topic due to the industry demand for high-performance low-cost thin-film transistors. In vertical transistors the channel length is determined by the semiconductor film thickness. Therefore, it is possible to fabricate a short channel high-performance device in spite of the organic semiconductors’ relative low mobilities. In our design of vertical transistors the gate electrode is located beneath the source electrode and controls the amount of carriers injected from the source electrode to the organic semiconductor. From the semiconductor the carriers swiftly cross the very short channel length towards the drain electrode. We developed a new fabrication process of n-type and p-type vertical transistors reaching on/off over 105 and current densities above 10mA per cm2. Complementary inverters were successfully assembled using those transistors.

Owing to the patterned source electrode technic, the gate is able to induce an efficient potential barrier lowering between the source electrode and the semiconductor. The fabrication process is compatible with large-area and low-cost fabrication. Using simple one step photo-lithography and lift-off process patterned electrode with holes in sizes of 2-20 µm is fabricated. In this process a blocking layer is added on the top of the source electrode in order to reduce off currents for better performances. To achieve high on/off ratio there must be an injection energy barrier between the source and the organic semiconductor. When using gold as source electrode it is possible to fabricate P-type and N-type transistor at the same process just by changing the organic semiconductor casting.




Pramod Kumar1, Yulia Gerchikov2, Shivananda Kammasandra Nanajunda2, Anat Sadeh3, Yoav Eichen2, Nir Tessler3

1 551, Nanoelectronics Center; Technion-Israel Institute of Technology
2 Schulich Faculty of Chemistry; Technion
3 Nanoelectronics Center; Department of Electrical Engineering

Statistical field effect transistor (SFET) – collective use of organic single crystals
Pramod Kumar1, Yulia Gerchikov2, Shivananda Kammasandra Nanajunda2, Anat Sadeh1, Yoav Eichen2, Nir Tessler1
1. Nanoelectronics Center, Department of Electrical Engineering, Technion, Haifa, Israel. 2. Schulich Faculty of Chemistry, Technion, Haifa, Israel.
Manufacturing organic field effect transistors (OFETs) from single crystals requires complex procedures for preparation of single crystals and their alignment at the exact right position. This is in contrast to the ease of fabrication of organic thin film transistors (OTFTs) through either spin coating, printing, or various evaporation methods. There have been a great deal of research in single crystal transistors as it offers high mobility and better device performance and stability due to less defects and grain boundaries than the thin films. Here we demonstrate a new type of transistor which can be prepared with similar ease as thin films but is based on collective use of single crystals. The fabrication is carried out with the aid of stencils mask pattern to yield a device structure we call Organic single crystallites Statistical Field Effect Transistor (OSFET). The concept of the statistical FET (SFET) structure is to first grow many crystallites on gate dielectric such that they form a discontinuous poly crystalline layer of sizes smaller than the channel length. Through one additive step that deposits conducting round disks, over the entire area, the crystallites become inter-connected. In fact, the new device is now being composed of many transistors interconnected in series and in parallel. The odds that a given crystallite is being contacted on both sides and the number of crystallites connecting two conducting circles are a statistical issue and hence the name of this structure: statistical field-effect transistor (SFET).
Our results suggest that unlike single crystal transistors, OSFETs do not require tedious fabrication process, can be easily prepared with the aid of a single additive step.




Chen Stern1, Doron Naveh1

1 Bar-Ilan University; Bar-Ilan University

Poster submission
Synthesis and Characterization of Large-scale CVD MOS2

Chen Stern and Doron Naveh,
Faculty of Engineering, Bar-Ilan University,
the zero
bandgap of graphene limits its applications in nanoelectronics
and optoelectronics
the zero
bandgap of graphene limits its applications in nanoelectronics
and optoelectronics

Few-layer molybdenum disulfide (MoS2) is a semiconductor material with outstanding potential for high-performance and low-power electronic devices. Among its prominent properties are large bandgap, high quantum luminescence efficiency, relatively high electron mobility, and chemical stability. Field effect transistors show excellent on-off current ratio, low subthreshold swing and high photo responsivity. The emergence of viable technologies based on MoS2 requires high quality, wafer-scale samples. Here we report on synthesis of large-area of MoS2 films on SiO2 substrates using a chemical vapor deposition (CVD). Our samples have long-range order and thickness uniformity. The quality the MOS2 is evaluated by the signature of Raman scattering. Electrical characterization of MOS2 based transistors synthesized by CVD is to be presented.




Kevin Rietwyk1

1 Bar Ilan University; Bar Ilan University

Energetics of All Metal Oxide Junctions
During the 1990s a major breakthrough in thin film technologies was achieved with the application of metal oxide buffer layers between organic/polymer layers and metal electrodes. This improved the energy level alignment between the layers, resulting in a drastic enhancement in the performance of a range of devices. There has since been growing interest in active metal oxide layers, due to their high abundance, stability, and low-cost processing. Consequently, metal oxides are more frequently grown as adjacent layers in thin film devices. However, the underlying mechanisms that determine the energetics across all metal oxide interfaces have yet to be extensively investigated. To address this shortcoming we have developed an innovative depth profiling method.
Exploiting the proven combinatorial metal oxide growth techniques we deposit a metal oxide layer with a thickness gradient onto a homogeneous metal oxide layer. Depth profiling is then achieved by laterally scanning the energetics across the sample using scanning Kelvin probe, air photoemission and UV-Vis optical analysis and correlating the measured properties of the layer to the thickness. From this an entire band diagram of the entire active depth of the junction can be developed. To demonstrate the power of this technique we will provide a complete band diagram of the TiO2-Co3O4 heterojunction which has recently shown promise in all oxide photovoltaics and water splitting.




Eldad Peretz1, Doron Naveh2

1 Bar Ilan University; Faculty of Engineering
2 Bar-Ilan University; Bar-Ilan University

Toward Single Electron Transistor device based on 2D TMD
Eldad Peretz and Doron Naveh
Faculty of Engineering, Bar-Ilan University

Two-dimensional layered materials are considered promising for advanced technologies due to their physical and chemical properties that are suitable for advanced electronic applications including nanoelectronics, optoelectronics and spintronics.
Within this class of materials, the transition-metal dichalcogenides (TMDs) and particularly single layer molybdenum disulfide (SL-MoS2) are amongst the most promising semiconductors for applications in nanoelectronic and in quantum information processing devices. These materials are under extensive research for device applications and for physical phenomena possessed by them, including field effect transistors, photodetectors, cathodoluminescent diodes, magneto-transport measurements and more.
Herein, we discuss a prototype of devices that have yet been demonstrated on TMDs: single electron transistor (SET). SET devices have high sensitivity to changes in the surrounding electrostatic field. Even minor changes in proximity to the device will affect the conductance through the SET and hence will be observable in measurements. This property makes SET an important building block in realization of quantum bits (Qubits) and serves as charge sensor and electrometer in nanoelectronic and quantum information processing devices.




Arie Borenstein1, Doron Aurbach2

1 Bar Ilan University; Bar Ilan University
2 Bar-Ilan University; Bar-Ilan University

Electric conductivity of metal organic framework-based compositions
A. Borenstein*, O. Fleker, R. Lavi, L. Benisvy, S. Ruthstein, and D. Aurbach
The Chemistry Department, Faculty of Exact Sciences, Bar Ilan University, Ramat-Gan, Israel, 5290002
* Corresponding author:

Metal Organic Frameworks’ (MOFs) unique properties make them superb candidates for many high-tech applications. However, their non-conducting character suppresses their practical utilization in electronic and energy systems. Using the familiar HKUST-1 MOF as a model system, we present a new method of gaining electrical conductivity to otherwise non-conducting MOFs by preparing MOF nanoparticles within the conducting matrix of mesoporous activated carbon (AC). This composite material was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), gas adsorption measurements, and electron paramagnetic resonance (EPR) spectroscopy. We show that MOF nanoparticles grown within the carbon matrix maintain their original unique crystalline and surface area. Owing to the composition process, EPR measurements surprisingly revealed a copper signal that was not achieved so far. We could analyze for the first time the complex EPR response of HKUST-1. We demonstrate the high conductivity of the MOF composite and discuss various factors that are responsible for these results. Finally, we present an optional application for using the conductive MOF composite as a high-performance electrode for pseudo capacitors.




Ofer Sinai1, Hadas Alon2, Ashwin Subramaniam3, Egle Puodziukynaite4, Ryan Selhorst4, Todd Emrick4, Doron Naveh1

1 Bar Ilan University; Bar Ilan University
2 Bar-Ilan University; Bar Ilan University
3 Department of Industrial and Mechanical Engineering; University of Massachusetts,
4 Department of Polymer Science and Engineering; University of Massachusetts,

Two-dimensional (2D) semiconductors based on the Mo and W family of layered transition metal dichalcogenides (TMDCs) are highly attractive for digital logic and near-IR photonics. However, their widespread incorporation into devices is hindered by the lack of robust strategies for controlling carrier densities through doping, as well as by the difficulties inherent in precise, scalable engineering of semiconductor heterojunctions. Taking advantage of the exquisite sensitivity of 2D materials to their immediate environment, we apply an ‘extrinsic’ approach to work-function engineering and carrier doping of TMDCs. Using e-beam lithography techniques, mechanically exfoliated MoS2 is contacted with Cr/Pd electrodes, whereby its transport properties are assessed. Additional patterning steps allow us to selectively expose the device to specially-designed functional polymers, yielding precise spatial control over carrier doping within different regions of the same flake. This control makes possible the construction of basic building blocks of integrated circuits, e.g., diodes, bipolar transistors, and inverters. This new class of hybrid polymer-2D materials promises scalable and low-cost engineering of optoelectronic functionality within TMDC monolayers.




Ella Sanders1, Regev Ben Zvi Bechler1, Ernesto Joselevich1

1 Department of Materials and Interfaces; Weizmann Institute of Science

Semiconductor nanowires (NWs) are important materials, found today in the basis of many potential nanotechnological applications and scientific research. Recently, our group has reported a new approach for the guided growth of aligned horizontal GaN, ZnO and ZnSe NWs on different substrates (sapphire (α-Al2O3), quartz, SiC, spinel), via the vapor-liquid-solid (VLS) mechanism. This new method enables control over the NWs location, growth direction and crystallographic orientation, and can lead to specific design and assembly of nanodevices. GaN specifically is an important semiconductor having a wide direct band-gap of 3.4 eV in the UV range, suitable for different electronic and optoelectronic applications. GaN NWs are unintentionally n- doped due to nitrogen vacancies and/or oxygen impurities, which often causes a high concentration of charge carriers. This often reduces their field-effect mobility, and hence the performance of nanowire-based transistors is affected. Here we demonstrate the control of the unintentional-doping level, using alumimium as an oxygen getter agent in the synthesis of GaN nanowires. In the chemical vapor deposition (CVD) system, the alumimium precursor can react with the oxygen in the reactor, originating from the Ga2O3 precursor and different impurities in the system. This can possibly allow the growth of GaN NWs with less oxygen impurities in the lattice, bringing down the n-doping level. The guided nanowires were examined in different compositional analysis methods (EELS spectroscopy, EDS and photoluminescence), which showed that the aluminium is not incorporated in the GaN nanowire lattice (no more than 2%). Electrical measurements show higher resistivity for GaN NWs grown with aluminium, and much higher response to gating measurements. These findings can indicate that the aluminium probably acts as an oxygen getter agent during the synthesis. This gettering method is thus shown to enable control of the electrical properties of guided nanowires.




Hadar Ben-Yoav1

1 Department of Biomedical Engineering; Ben-Gurion University of the Negev

Electrochemical biosensors for point-of-care monitoring in mental health
Hadar Ben-Yoav 1,2,*, Thomas E. Winkler 2, George Banis 2, Sheryl E. Chocron 2, Eunkyoung Kim 2, Deanna L. Kelly 3, Gregory F. Payne 2, and Reza Ghodssi 2
1 Ben-Gurion University of the Negev, Beer Sheva, Israel; 2 University of Maryland, College Park, 3 University of Maryland School of Medicine, Baltimore, Maryland, United States; * Corresponding author:
We present the first demonstration of an electrochemical micro-system for real-time biosensing of the antipsychotic clozapine (CLZ) towards point-of-care Schizophrenia treatment monitoring. The biosensor is based on a multi-sensor approach that integrates chitosan-modified semi-selective sensors, i.e. a catechol-chitosan redox cycling system and a carbon nanotubes (CNTs) –chitosan composite (Figure 1). Here, we show the development of the microfabricated biosensor and the miniaturization of the redox-cycling system that results in the amplification of the electrochemical signal generated by CLZ (Figure 2). The catechol-chitosan integrated biosensor demonstrates a sensitivity of 54 µC×mL/cm2×µg and a limit-of-detection of 0.8 µg/mL (Figure 3), that enables detection in high interference biological samples such as Schizophrenia patients’ serum.
1. H. Ben-Yoav, T.E. Winkler, E. Kim, S.E. Chocron, D.L. Kelly, G.F. Payne, R. Ghodssi, Electrochimica Acta 130, p. 497, 2014.
2. H. Ben-Yoav, S.E. Chocron, T.E. Winkler, E. Kim, D.L. Kelly, G.F. Payne, R. Ghodssi, Electrochimica Acta 163, p. 260, 2015.




Or Zolti1, Fernando Patolsky2

1 Tel Aviv University; Department Of Material Science and Engineering
2 School of Chemistry; School of Chemistry

Or Zolti* and Fernando Patolsky
Contamination of airborne molecular contamination (AMC) is responsible for numerous defects in integrated circuit manufacturing [1],[3]. The ability to sense these contaminations “in-situ” within the fabrication line vacuum chambers will allow yield increase and cost reduction. Effective detection of those AMC with selective properties are vital to insure that contaminators are not damaging the processes and machinery within the very large scale integration (VLSI) production line [3]. In our research the detection was done by exploiting the electric characteristics of Si nanowire field-effect transistors sensors (Si NWFET). The use of SiNW FET are showing promising capabilities in the recognition of the contaminating species, even at low concentrations as low as 400ppt (parts-per-trillion) in their gaseous phase. SiNW FETs provide advantages when compared to other sensing methods such as: low power consumption, gate voltage controllability, simple multiple device signals analysis, and their small dimensions [2]. We will present a novel use of SiNW FETs to detect AMCs, with detection times of a few seconds. By heating permeation tubes in an oven, with a constant flow of N2 carrying gas, we were able to control the concentration of the AMCs. In order to detect the AMCs we have modified the SiNWs surface with different silane-derivative molecular layers, and tested the change of electrical current through the NWs devices in response to their interaction with the AMCs molecular species. The AMC molecules, physisorbed to the modified SiNWs surface, induced a change in the surface potential of the NW-based sensing devices, which resulted in change of current through the NWs. In this work we have successfully tested the presence of Acetone and NMP molecules, while using different modifications.




Beatrice Miccoli1, Alberto Bonanno2, Alessandro Sanginario2, Valentina Cauda3, Danilo Demarchi4

1 Politecnico DI Torino; Department of Electronics and Telecommunications
2 Center for Space Human Robotics@polito; Istituto Italiano DI Tecnologia
3 Center for Space Human Robotics@polito and Politecnico DI Torino; Politecnico DI Torino
4 Center for Space Human Robotics@polito and Politecnico DI Torino; Department of Electronics and Telecommunications – Politecnico DI Torino

State-of-art research on high-performing sensors often rely on the remarkable and distinctive properties of nano-structures. Indeed, nanomaterials can interact with the surrounding environment at the nanoscale leading to sensors with improved sensitivity and limit-of-detection. Accurate Read-Out-Circuits (ROCs) are needed to directly measure small variations of resistance and capacitance of the nanomaterial during the sensing process. The presented multi-sensor CMOS platform (Figure 1-d inset), integrates the electronics able to read-out, in real-time, the conductance of different nanostructures deposited onto 24 couples of metal electrodes placed on the chip surface. The 130 nm CMOS chip both controls the nanostructure deposition by enabling a dielectrophoresis (DEP) signal on each couple of electrodes and reads-out the nanostructure electrical properties. DEP does not require any further contact deposition allowing high chip reusability by removing the nanostructure through sonication. The nanostructure/electrodes electrical contact is improved through a chemical CMOS post-processing. Therefore, the top surface of the original Al electrodes is covered with Au (Figure 1-a), less prone to oxidation. As proof-of-concept, zinc oxide nanowires (ZnO-NWs) are deposited across different couples of gold electrodes (Figure 1-b) successfully exploiting the DEP circuit on-chip. The variation of the ZnO-NW resistance, RNW, under UV-visible light is then investigated using the chip ROCs. As expected1, RNW significantly decreases (up to 93% of the dark value) for increasing irradiances (Figure 1-d). To further test the multi-sensing concept, Mo6S4I6-NWs are also integrated on the same chip (Figure 1-c) enabling the DEP signal on different electrodes. This opens the future for new combined sensing measurements potentially involving different NWs and thus sensing properties, at the same time.
Figure-1. (a) CMOS post-processing. (b) SEM image of a ZnO-NW across gold electrodes. (c) DEP results with: ZnO-NWs (l≈10 µm, d≈600 nm) and Mo6S4I6-NWs (l≈15 µm, d≈100 nm). (d) ZnO-NW UV-visible light characterization on chip (inset).

[1] B. Miccoli, A. Bonanno, et al., in IEEE 38th Int. Spring Seminar on Elec. Tec. (ISSE), 2015, 431.




Edith Beilis1

1 Tel Aviv University; Tel Aviv University

Doping Effect on BSA Self Assembled Monolayers Electrical Properties:
Chemically Resolved Electrical Measurements Analysis
Edith Beilis1, Bogdan Belgorodsky2, Ludmila Fadeev2, Hagai Cohen*3, Shachar Richter*1
1 Center for Nanoscience and Nanotechnology, 2 School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University
3 Department of Chemical Research Support, Weitzman Institute of Science, Rehovot
E-mail address:
Evidence for considerable improvement in conductivity of Self Assembled Monolayers (SAMs) composed of Bovine Serum Albumin (BSA , a transport protein without redox activity) via complexion with tetraphenyl-21H,23H-porphine (TPP) and its metallo- derivatives with copper and iron is provided. This is compared to the properties of the bare BSA and its corresponding monolayer.
As we have previously shown1,2,the doping action, namely the incorporation (non covalently) of small hydrophobic molecules to BSA, affects inter and intra molecular forces and thus affects the surface induced conformational changes of BSA upon adsorption to gold. This phenomenon has been also correlated to the morphological properties of the corresponding SAMs as well as changes in BSA molecules dehydration upon adsorption.
By using the unique technique of Chemically Resolved Electrical Measurements (CREM)3,4 we provide I-V characteristics of selected sub-surfaces domains (specific chemical elements) within the monolayer along with X-ray photoelectron spectroscopy (XPS) measurements. Thus the doping effect on the layer’s electrical properties is evaluated in regards to: its morphological properties as well as intrinsic properties such as specific elemental tendency to accumulate charge (electrons/holes).
(1) Beilis, E.; Belgorodsky, B.; Fadeev, L.; Cohen, H.; Richter, S. Journal of the American Chemical Society 2014, 136, 6151.
(2) Mentovich, E.; Belgorodsky, B.; Gozin, M.; Richter, S.; Cohen, H. Journal of the American Chemical Society 2012, 134, 8468.
(3) Cohen, H. J Electron Spectrosc 2010, 176, 24.
(4) Doron-Mor, H.; Hatzor, A.; Vaskevich, A.; van der Boom-Moav, T.; Shanzer, A.;
Rubinstein, I.; Cohen, H. Nature 2000, 406, 382.




Matias Katz1

1 Technion; Technion

Light direction-dependent plasmonic enhanced GaN/AlN quantum cascade detector
Matias Katz1*, Asaf Pesach1, Etienne Giraud2, Martin Denis2 ,Ofir Sorias1, Lior Gal1, Meir Orenstein1, Nicolas Grandjean2, and Gad Bahir1

1Department of Electrical Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
2Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
Author e-mail address:
The Quantum cascade detector (QCD) has emerged in recent years as an alternative for quantum well infrared photodetector (QWIP). The fundamental building-block of a QCD consists of an active quantum well (QW) where electron excitation occurs upon photon intersubband (ISB) absorption, and multi-quantum well extractor that transfers the excited electron to the ground level of the following active QW. Major drawback of the QCD in applications based on normal light incidence is related to the polarization selection rule of QW inter-subband (ISB) transitions, allowing absorption only for an electric field polarized perpendicular to the QW layers (Ez). The use of two dimmensional metallic holes arrays (MHAs) allows coupling surface plasmons (SP) to absorption region of the QCD. The generated SP is a TM mode thus exhibits a dominant electric field component normal to the surface that is the proper polarization for exciting the ISB resonance. Recently, a normal-incident plasmonic GaN/AlN QCD was introduced by our group. In the present work we show experimentally and by simulation that plasmonic enhancement performance of a QCD integrated with top MHA depends on the direction of the incidence light; normal Front Illumination (FI) or Backside Illumination (BI). In the study, it is shown that BI considerably increases the light coupling strength compared with FI. The peak responsivity is incresead from 1.77 to 2.72 mA/W at 1.82 μm by changing the light direction. For studying the effect of plasmonic Ez field depth decay on QCD performance, further work is being done on a new QCD sample that consists of 3 active periods and the results will be presented at the conference.




Roman Zhuravel1

1 Institute of Chemistry and The Harvey M. Krueger Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem; Givat Ram

Towards electrical transport measurements through single DNA molecules
Roman Zhuravel1, Haichao Huang1, Haya Dachlika1, Avigail Slutzkin1, Dvir Rotem1, Shalom Wind2 and Danny Porath1
1 Institute of Chemistry and The Harvey M. Krueger Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Israel
2 Department of Applied Physics and Applied Mathematics Center for Electron Transport in Molecular Nanostructures, Columbia University, New York, USA

The field of Nano-electronics concentrates a lot of interest from technological and scientific point of view. The technological interest is obvious as the semi-conductor industry approaches the nanometric scales and seeks for further device miniaturization. It raises many scientific questions and challenges, one of them is understanding the charge transport in single molecules. While charge transport in the solid state has been widely researched, for large single molecules many fundamental questions remain unsolved.
DNA is a good model molecule for many polymeric systems and its structure suggests the possibility for significant charge transport. Charge migration along DNA molecules has attracted scientific interest for over half a century. However, due to the many free parameters concerning these experiments, a variety of results were achieved triggering an ongoing scientific debate on the DNA molecule conductivity. Our goal in this research is to eliminate as many degrees of freedom as possible.
We create dimers of gold nanoparticles bridged by exactly one DNA molecule. Each nanoparticle is connected to the DNA trough one thiol. This system is very well-defined with minimum number of unknown parameters. The dimer is brought to a small gap between pointing electrodes by dielectrophoresis for further electrical characterization. Our system enables precise measurements with very good control of many environmental parameters such as temperature, atmosphere etc. These measurements have already generated promising preliminary results.




Iftach Ilsar1, Arthur Shapiro2, Efrat Lifshitz2, Yoram Selzer1

1 Tel Aviv University; School of Chemistry
2 Technion; Faculty of Chemisrty

Statistical analysis of photo-induced switching in nanoantenna-junctions embedded with PbSe semiconductor colloidal quantum dots.
We study the influence of light on electron transport in plasmonic nanoantenna electrical junctions embedded with ~5nm PbSe Semiconductor Colloidal Quantum Dots (SCQD). In these junctions, the origin of photocurrents may be quite involved owing to several possible mechanisms which influence the junction’s conductance under illumination. These may include photo excitation of the QDs, interaction of photons with the metal leads, plasmonic enhancement of the electric field in the junction’s gap, heating effects and more. Distinguishing between the different photocurrent constituents is very challenging and yet highly important for the use of such junctions in numerous applications. To tackle this difficulty, we exploit the unique phenomena of switching in SCQD junctions, conventionally attributed to random charge trapping events in trap states of the SCQD, to distinguish between the various possible photo-effects by statistical analysis methods.




Naomi Kramer1, Nurit Ashkenasy1

1 Ben Gurion University of the Negev; The Department of Materials Engineering

Amino acids based-monolayers for tuning surface electronic properties of conductive oxides
Naomi Kramer and Nurit Ashkenasy
The department of Materials engineering,
Ben-Guriun University of the Negev, Beer Sheva , Israel
Organic based optoelectronics devices have a promising potential in various applications. Energy band alignment at interfaces between the organic layers and indium tin oxide (ITO), a commonly used electrode, is extremely important for the efficiency of these devices. Using organic monolayers as a mean to control the work function of the conductive oxide via the molecular dipole moment and/or charge redistribution has shown to be an effective way for tailoring the interfacial electronic properties without hindering the overall performance of such devices. In this respect, amino acids provide a versatile platform to control ITO work function, since they easily form monolayers by attaching to the surface through their carboxylic residue, enabling their side groups to tune the electronic properties. Here, we show the effect of selected amino acids’ side chain on the electronic properties of ITO.
Monolayers of Lysine, Glutamic acid and Tyrosine were assembled on ITO in order to study the effect of positively charged, negatively charged and aromatic side chains (respectively) on the work function and surface photovoltage of the surface, while bare ITO and Glutamine (uncharged side chain) were chosen as reference. Our results show that Lysine monolayers decrease the work function due to positive dipole moment while Tyrosine monolayers increase the work function due to negative dipole moment. Glutamic acid monolayers decrease the work function, probably due to adsorption through both carboxylic groups. Surface photovoltage spectroscopy studies show an increase in the band bending in all cases, except for Tyrosine, in respect to bare ITO, showing charge redistribution at the surface. These results present a simple and versatile process for tuning the electrical properties of conductive oxide surfaces using amino acids.




Avigail Stern1, Dvir Rotem1, Suzanna Azoubel2, Shlomo Magdassi3, Danny Porath1

1 Hebrew University; Givat Ram
2 The Hebrew University of Jerusalem; Givat Ram
3 The Hebrew University of Jerusalem; Chemistry

Electrical Characterization of 1D Molecular Structures

Avigail Stern1, Gideon I. Livshitz1, Dvir Rotem1, Suzanna Azoubel1, Shlomo Magdassi1, Danny Porath1*

1Institute of Chemistry and The Harvey M. Krueger Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, 91904 Israel
Charge transport through 1D polymers is intriguing, but extremely challenging to research. Detailed research of the mechanism of such transport has been detained, mainly due to shortage of reliable charge transport measurements through such molecules. In order to supply this shortage a reliable measurement setup was recently developed in our lab, that is suitable for measurement of molecules tens to hundreds of nanometers long. This setup involves a stationary gold electrode that is evaporated over the molecules of interest and a conductive AFM tip serving as a second mobile electrode that contacts single molecules protruding from the gold electrode. We used the technique to characterize the conductivity of a SWCNT network before and after HNO3 fume treatment, and concluded that the fumes improve the network conductivity by decreasing the resistance at CNT junctions. In addition we are attempting to implement the technique for measurements of single non-crystalline 1D molecules.




Himanshu Shekhar1, Nir Tessler2

1 Technion Institute; Electrical Department
2 Nanoelectronics Center; Department of Electrical Engineering

To achieve efficient organic photodiode (OPD) for their use as photodetector in image sensor, donor and acceptor molecules are co-evaporated to form the photoactive layer in the device. The effect of the mixing ratio of copper-phthalocyanine (CuPc) and C60 in the photoactive layer on the optical and electrical device performance is investigated by solar cell characterization measurements. We find that a 70:30 (vol %) mixing ratio in CuPc:C60 blend gives maximum short-circuit current and highest power conversion efficiency (PCE).
We studied the effect of various active layer thicknesses, ranging from 40nm to 120nm, on the device performance. The results show that the device with 40nm thick active layer has best photodiode characteristic parameters. Morphological analysis using AFM and SEM of 40nm and 120nm films revealed difference in grain sizes and their distribution across the film. Thin film has smaller grains with a well interconnecting network compare to the thick film, this was also confirmed from intensity vs efficiency measurement1. The later measurement also shows higher generation efficiency for the thinner device despite absorbing less light (45% in thin film compare to 70% in thick) as found using optical modeling. Moreover, 34% drop in efficiency, moving from low light intensities to one sun, is observed for thicker film compare to only 10% drop for the thin film. We believe that the superior performance of thin active layer device is associated with the film morphology leading to lower losses.
Our device, a photodiode, has short-circuit current of 7.80 mA/cm2 and 1.80% PCE. The dark current rectification ratio (Ion/Ioff) between -2V and 1V is more than 105 which is better than reported for the similar material system2.
1. Tzabari, L. and Tessler, N., Role of Charge Transfer States in P3HT-Fullerene Solar Cells. J. Phys. Chem. C, 118(48), 2014, 27681-27689
2. Sullivan, P., et al., Influence of Co-deposition on the Performance of CuPc-C60 Heterojunction Photovoltaic Devices. Applied Physics Letter, 84 (2004)




Erez Zion1

1 Bar-Ilan University; Max and Anna Web St.

Localization of Charge Carriers In Monolayer Graphene Gradually Disordered by Ion Irradiation

Erez Zion1, Alexander V. Butenko1, Leonid Wolfson3, Yuri Kaganovskii3, Amos Sharoni1, Doron Naveh2, Vladmir Richter4, Moshe Kaveh3, Eugene Kogan3, Issai Shlimak3
1 Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, Israel
2 Faculty of Engineering, Bar-Ilan University, Ramat-Gan, Israel
3 Jack and Pearl Resnick Institute, Department of Physics, Bar-Ilan University, Ramat-Gan, Israe
4 Solid State Institute and Physics Department, Technion-Israel Institute of Technology, Haifa, Israel

Gradual localization of charge carriers is studied in a series of micro-size samples of monolayer graphene fabricated on the common large scale film and irradiated by different doses of C+ ions with energy 35 keV. Measurements of the temperature dependence of conductivity and magnetoresistance in fields up to 4 T show that at low disorder, the samples are in the regime of weak localization and antilocalization. Further increase of disorder leads to strong localization regime, when conductivity is described by the variable-range-hopping (VRH) mechanism. A crossover from the Mott regime to the Efros-Shklovskii regime of VRH is observed with decreasing temperature. Theoretical analysis of conductivity in both regimes shows a remarkably good agreement with experimental data.




Hela Sasson1, Yulia Furmansky2, Jose .M. Alonso3, Han Zuilhof3, Iris Visoly-Fisher4

1 Ben Gurion University ; Ilse Katz Institute for Nanoscale Science & Technology
2 Ben Gurion University; Ilse Katz Institute for Nanoscale Science & Technology
3 Wageningen University; Wageningen University
4 Swiss Institute for Dryland Environmental and Energy Research; Swiss Institute for Dryland Environmental and Energy Research

Hela Sassona, Yulia Furmanskya, b, c, Jose M. Alonsod, Han Zuilhofd, Iris Visoly-Fishera, c.
aDept. of Solar Energy and Environmental Physics, Jacob Blaustein Inst. for Desert Research, Sede Boqer campus, bDept. Of Materials Eng., cIlse Katz Institute for Nano-scale Science and Technology, Ben-Gurion University of the Negev, Israel.
dLaboratory of Organic Chemistry, Wageningen University, Wageningen, The Netherlands.
Indium tin oxide (ITO) is widely used as a transparent electrode in optoelectronic devices. ITO is known to have in-gap surface states due to its non-perfect nature, which affect charge transport across its interface with other (opto)electronic materials [1]. Accordingly, ITO/PEDOT:PSS junctions have shown significant UV photoconductance due to photoinduced discharging of ITO surface states resulting in a decrease of the ITO’s surface band bending. In contrast, we show that 1-alkenes adsorbed in ITO surface via the formation of an C−O−In(Sn) linkage [2], and n-phosphonic acids adsorbed via OH, have shown negligible such photoconductance. Furthermore, Kelvin probe measurements of the work function showed very small surface photovoltage. This possibly indicates passivation and discharging of ITO surface states by adsorption via C−O−In(Sn) or phosphonic acid linkage. Passivation of surface states and elimination of the ITO photo-response could be highly significant for the use of ITO in optoelectronic devices such as OLEDs and solar cells.

[1] Y. Gassenbauer and A. Klein, “Electronic and Chemical Properties of Tin-Doped Indium Oxide (ITO) Surfaces and ITO/ZnPc Interfaces Studied In-situ by Photoelectron Spectroscopy” J. Phys. Chem. B. 110, pp. 4793-801,2006.
[2] Y. Li and H. Zuilhof, “Photochemical grafting and patterning of organic monolayers on indium tin oxide substrates” Langmuir 28, pp. 5350–9, 2012.




Moshe Kirshner1

1 Bar Ilan University; Bar Ilan University

Eldad Peretz, Doron Naveh

Thermoelectric effects in graphene, a two dimensional electron gas of Dirac Fermions are well recognized.  Here we induce bipolar junctions in graphene field effect transistors via interfacial doping and study the temperature-dependent transport. The character of charge carrier distribution is devised from transport measurements and the thermal generations, and the resulting thermo-power is estimated in asymmetric interdigitated transistors.





Hadas Alon1

1 Bar-Ilan University; Bar Ilan University

Graphene pn Junctions Achieved by Soft Doping with PSBMA
Hadas Alon1,2, Vlada Artel1,2, Chaim N. Sukenik1, Ashwin Ramasubramaniam3, Egle Puodziukynaite4, Ryan Selhorst4, Todd Emrick4, and Doron Naveh2

1 Department of Chemistry and Bar-Ilan Institute for Nanotechnology and Advanced Materials, Ramat-Gan 52900
2 Faculty of Engineering and Bar-Ilan Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900
3 Department of Industrial and Mechanical Engineering, University of Massachusetts, Amherst, MA
4 Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA
Graphene, a single layer of carbon atoms arranged in a honeycomb lattice, is one of the most fascinating and promising electronic materials known. While its atomic thickness is a significant advantage in many respects, this unique structure creates a serious challenge in developing the controlled modification of its charge carrier concentration. In this work, we demonstrate a viable strategy for achieving substantial control over the charge carrier concentration in graphene. It is achieved by using patterned structures of polymers that exhibit charge transfer with graphene. The patterning is achieved by conventional lithography and the work-function engineering is provided by the charge transfer between the graphene and the overlaid polymer. This conceptually simple and versatile approach will be applied to devices built around graphene-based PN junctions that can be used in photodetectors and transistors.




Tamar Yelin1, Richard Korytar2, Nirit Sukenik1, Ran Vardimon1, Bharat Kumar3, Colin Nuckolls3, Ferdinand Evers2, Oren Tal1

1 Weizmann Institute of Science; Chemistry
2 Regensburg University; Theoretical Physics
3 Columbia University; Chemistry

Single molecules set the ultimate miniaturization limit of conductive components in electronic circuits. A major challenge of molecular electronics is to achieve high and robust conductivity. However, it is not clear what is the upper boundary for conductance across a single molecule and what are the factors that would determine this limit. We addressed these questions by studying the effect of molecule length on the conductance in metal-molecule-metal junctions, based on a series of oligoacene molecules. We found that the conductance can reach an upper limit where it is independent on molecule length. Furthermore, we found that this limit can be controlled by rational orbital hybridization at the metal-molecule interface. Interestingly, the evolution of conductance towards its upper limit can be understood with the aid of a simple analytical model. Our findings shed light on the mechanisms that determine the upper limits for conductance across molecules, providing guiding principles for the design of highly conductive metal-molecule interfaces.




Eldad Peretz1, Doron Naveh2

1 Bar Ilan University; Faculty of Engineering
2 Bar-Ilan University; Bar-Ilan University

Toward Single Electron Transistor device based on 2D TMD
Eldad Peretz and Doron Naveh
Faculty of Engineering, Bar-Ilan University

Two-dimensional layered materials are considered promising for advanced technologies due to their physical and chemical properties that are suitable for advanced electronic applications including nanoelectronics, optoelectronics and spintronics.

Within this class of materials, the transition-metal dichalcogenides (TMDs) and particularly single layer molybdenum disulfide (SL-MoS2) are amongst the most promising semiconductors for applications in nanoelectronic and in quantum information processing devices. These materials are under extensive research for device applications and for physical phenomena possessed by them, including field effect transistors, photodetectors, cathodoluminescent diodes, magneto-transport measurements and more.
Herein, we discuss a prototype of devices that have yet been demonstrated on TMDs: single electron transistor (SET). SET devices have high sensitivity to changes in the surrounding electrostatic field. Even minor changes in proximity to the device will affect the conductance through the SET and hence will be observable in measurements. This property makes SET an important building block in realization of quantum bits (Qubits) and serves as charge sensor and electrometer in nanoelectronic and quantum information processing devices.




Leah Ben Gur1, Einat Tirosh1, Amir Segal2, Gil Markovich1, Alexander Gerber2

1 School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences; Tel-Aviv University
2 School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences; Tel-Aviv University

In the past few years printed electronics technology has been developing vastly. This field is oriented towards the low-cost and high volume printed circuit market, where the high performance of conventional electronics is not required.
In this work we have developed printable magnetic thin-films consisting of nickel-nanoparticles ink, which, after drying under controlled conditions, exhibited a significant Extraordinary Hall Effect (EHE) signal (1-10mΩ). The EHE is a well-known effect in the field of ferromagnetic materials, where a voltage proportional to the magnetization across a current carrying magnetic film is generated. The origin of the EHE is spin-orbit scattering that breaks the spatial symmetry of scattered electrons. In cases of our interest the EHE contribution significantly exceeds the ordinary Hall- effect, resulting in a Hall voltage VH that is directly proportional to the magnetization M of the material and as such can be used for sensing magnetic fields.
An EHE sensor can exceed a sensitivity of 104 /T, which is an order of magnitude higher than the best sensitivity achieved in semiconducting Hall materials. An important feature of EHE, particularly relevant for printing technology, is that EHE signal increases with enhancement of electrical resistivity of the material. In other words, the performance of EHE sensors improves with imperfections. Thus, low quality of magnetic films fabricated by printing techniques is not expected to impede their performance.
Ni nanoparticles were selected due to the fairly low oxidation of the Ni on exposure to air, and the relative ease of reduction of the oxide to the metal form. In addition, Ni is a relatively soft magnetic material, which will ensure very low coercivity of the nanoparticle based magnetic sensor, increasing its field sensitivity around zero field.

A typical EHE measurement exhibited from a Ni NP Thin-film




Vadim Krivitsky1, Marina Zverzhinetsky1, Sharon Lefler1, Vladimir Naddaka1, Fernando Patolsky1

1 School of Chemistry; School of Chemistry

A Redox-Reactive Nanowire Biosensor for Multiplex Monitoring of Cellular Metabolic Activity

Vadim Krivitsky†,Marina Zverzhinetsky†, Sharon Lefler†,Vladimir Naddaka† and Fernando Patolsky†

†School of Chemistry, the Raymond and Beverly Sackler Faculty of Exact Sciences,
Tel-Aviv University, Israel

Silicon nanowire field-effect transistors (SiNW FETs) are potential leading candidates for monitoring cellular metabolic activity because they enable real-time, label-free detection of biological and chemical species. However, to conduct sensing in most biosamples of high ionic strength, the detection limit issue related to Debye length has to be resolved. We have developed a novel redox reactive SiNW FET array that enables to perform extracellular real-time multiplex monitoring of metabolites without any pre-processing of the sample, including desalting, directly from the cellular environment. This breakthrough was possible due to a new chemical modification approach performed on the SiNWs surface, which has sensitized them to a redox process on their surfaces. This redox-reactive SiNW FET was successfully utilized for various applications, such as estimating the metabolic activity of bacteria or evaluating chemotherapeutic treatments of cancer cells. Our redox-reactive SiNW-based FETs allow a multiplex, real-time, non-invasive, sensitive, selective, label free and robust detection of various metabolites. This sensing configuration can be performed in a wide range of applications, from food quality control, to point of care and personalized medicine.




Atindra Nath Pal1, Arindam Ghosh2

1 Weizmann Institute of Science; Department of Chemical Physics
2 Indian Institute of Science; Deaprtment of Physics

1/f noise as a probe to investigate the band structure of graphene
Atindra Nath Pal* and Arindam Ghosh
Department of Physics, Indian Institute of Science, Bangalore-560012, India.
The flicker noise or low frequency resistance fluctuations in graphene depend explicitly on its ability to screen external potential fluctuations and more sensitive compared to the conventional time average transport. Here we show that the flicker noise is a powerful probe to the band structure of graphene that vary differently with the carrier density for the linear and parabolic bands. We have used different types of graphene field effect devices in our experiments which include exfoliated single and multilayer graphene on oxide substrate, freely suspended single layer graphene, and chemical vapor deposition (CVD)-grown graphene on SiO2. We find this difference to be robust against disorder or existence of a substrate. Also, an analytical model has been developed to understand the mechanism of graphene field effect transistors. Our results reveal the microscopic mechanism of noise in Graphene Field Effect Transistors (GraFET), and outline a simple portable method to separate the single from multi layered graphene devices.

1. Atindra Nath Pal and Arindam Ghosh, Physical Review Letters 102, 126805 (2009).
2. Atindra Nath Pal and Arindam Ghosh, Appl. Phys. Lett., 95, 082105 (2009).
3. Atindra Nath Pal, Ageeth A. Bol, and Arindam Ghosh, Appl. Phys. Lett. 97, 133504 (2010).
4. Atindra Nath Pal et al., ACS Nano, 5, 2075 – 2081 (2011).




Sudipto Chakrabarti1, Biswajit Kundu2, Amlan Jyoti Pal2

1 Weizmann Institute of Science; Chemical Physics
2 Indian Association for the Cultivation of Science; Department of Solid State Physics

Electron delocalization in CdSe/CdS type−I core−shell systems: an insight from scanning tunneling spectroscopy
In this work, we choose CdSe/CdS type-I core−shell nano−heterostructures that evidence confinement of holes to the core only where as electrons are delocalized upto the shell layer1. Such selective confinement occurs due to a low energy−offset of the conduction band (CB) edges between core and the shell, resulting in delocalization of electrons upto the shell layer. Since such delocalization occurs through a thermal assistance, we study temperature dependence of selective delocalization process through scanning tunneling spectroscopy (STS). From the density of states (DOS), we observe that the electrons are confined to the core at low temperatures and above a certain temperature, they become delocalized up to the shell leading to a decrease in the CB of the core−shell system due to widening of quantum confinement effect. We record the topography of the core−shell nanocrystals by probing their CB and VB edges separately. The topographies recorded at different temperatures representing wave−functions of electrons and holes correspond to the results obtained from the DOS spectra. The results evidence temperature−dependent wave−function delocalization of one−type of carriers up to the shell layer in this core−shell nano−heterostructures.

Figure 1. DOS for CdSe/CdS core−shell nanocrystals at different temperatures. The CB and VB edges of the core−shells are marked with vertical lines at the positive and the negative voltages, respectively. Topography of a single nanostructure recorded with a positive or a negative voltage on the substrate and thus probing the CB or the VB of the nanostructures at the temperatures are shown in the right and left side of the corresponding DOS spectra. Dimension of all the images are 12 nm × 12 nm.
1. J. J. Li, Y. A. Wang, W. Z. Guo, J. C. Keay, T. D. Mishima, M. B. Johnson, X. G. Peng, J. Am. Chem. Soc., 2003, 125, 12567-12575.





Fernando Patolsky1, Alon Kosloff1, Omri Heifler2

1 School of Chemistry; School of Chemistry
2 Faculty of Engineering; Material Engineering Department

Nanochannel-embedded Silicon Nanowire FETs for single molecule detection
To increase sensing potential, silicon nanowires sensor arrays are confined along a nano-fluidic channel for the selective single molecule detection. The differential conductance of silicon nanowires, tuned with source-drain bias voltage, has been previously demonstrated to be highly sensitive to molecular charge. In this work, we have fabricated SiNWs-based FET (field-effect transistor) arrays, which based on the nano-channel diameter, show selectivity to molecular size. Furthermore, the nanochannel can also be selective to ion charge, either by modifying channels surface, or utilizing the electrical double layer effect. By applying electrophoresis principle, we can now investigate ion transport, nanochannels electrical cross section properties, and analyze low concentration samples, of high ionic strength, by eliminating the Debye screening length factor. By using simple electrical and optical measuring methods, we can validate molecule transport control in a 100nm thick channel, and distinguish between opposite-charged and size-varied macromolecules.