Showing papers presented at "International Conference on Nanotechnology in 2012"

Large single crystals of graphene on melted copper using chemical vapour deposition

Abstract: A simple one-step method is presented for synthesizing large single crystal graphene domains on melted copper using atmospheric pressure chemical vapour deposition (CVD). This is achieved by performing the reaction above the melting point of copper (1090 °C) and using a molybdenum support to prevent balling of the copper from dewetting. By controlling the amount of hydrogen during growth, individual single crystal domains of monolayer graphene greater than 200 µm are produced, determined by electron diffraction mapping. Angular resolved photoemission spectroscopy is used to show the graphene grown on copper exhibits a linear dispersion relationship and has no sign of doping.

Band-offset driven efficiency of the doping of SiGe core-shell nanowires

Abstract: Impurity doping of semiconducting nanowires is expected to become increasingly inefficient as the wire diameter shrinks down, because impurity states get deeper due to quantum and dielectric confinement. Here we show that efficient n- and p-type doping can be achieved in strongly confined SiGe core-shell nanowires, taking advantage of the type-II band offset at the Si/Ge interface. A one-dimensional electron (hole) gas is created at the band-edge and the carrier density is uniquely controlled by the impurity concentration with no need of thermal activation. Additionally, SiGe core-shell nanowires provide naturally the separation between the different types of carriers, electron and holes, and are ideally suited for photovoltaic applications.

Integrated quantum photonics

Abstract: Quantum information science aims to harness uniquely quantum mechanical properties to enhance measurement and information technologies, and to explore fundamental aspects of quantum physics. Of the various approaches to quantum computing [1], photons are particularly appealing for their low-noise properties and ease of manipulation at the single qubit level [2,3]. Encoding quantum information in photons is also an appealing approach to quantum communication, metrology (eg. [4]), measurement (eg. [5]) and other quantum technologies [6]. However, the implementation of optical quantum circuits with bulk optics has reached practical limits. We have developed an integrated waveguide approach to photonic quantum circuits for high performance, miniaturization and scalability [7]. Here we report high-fidelity silica-on-silicon integrated optical realizations of key quantum photonic circuits, including two-photon quantum interference and a controlled-NOT logic gate [8]. We have demonstrated controlled manipulation of up to four photons on-chip, including highfidelity single qubit operations, using a lithographically patterned resistive phase shifter [9]. We have used this architecture to implement a small-scale compiled version of Shor's quantum factoring algorithm [10], demonstrated heralded generation of tunable four photon entangled states from a six photon input [11], a reconfigurable two-qubit circuit [12], and combined waveguide photonic circuits with superconducting single photon detectors [13]. We describe complex quantum interference behavior in multi-mode interference devices with up to eight inputs and outputs [14], and quantum walks of correlated particles in arrays of coupled waveguides [15]. Finally, we give an overview of our recent work on fundamental aspects of quantum measurement [16,17] and diamond [18,19] and nonlinear [20,21] photon sources.

Meeting the challenges of oilfield exploration using intelligent micro and nano-scale sensors

Abstract: This paper describes the challenges of nano-scale sensor development for very harsh downhole oilfield conditions and provides an overview of the operational requirements necessary to survive and directly measure the desired subsurface data. One of the significant challenges is maintaining sensor accuracy and sensitivity as devices are miniaturized into the micron scale and below. The goal is to develop subsurface nanosensors that can be injected into oil and gas well bores to gather and report data, providing an unparalleled level of reservoir characterization.

Array-based disease diagnostics using lipid/polydiacetylene vesicles encapsulated in a sol-gel matrix

Abstract: We demonstrate a novel array-based diagnostic platform comprising lipid/polydiacetylene (PDA) vesicles embedded within a transparent silica-gel matrix. The diagnostic scheme is based upon the unique chromatic properties of PDA, which undergoes blue-red transformations induced by interactions with amphiphilic or membrane-active analytes. We show that constructing a gel matrix array hosting PDA vesicles with different lipid compositions and applying to blood plasma obtained from healthy individuals and from patients suffering from disease, respectively, allow distinguishing among the disease conditions through application of a simple machine-learning algorithm, using the colorimetric response of the lipid/PDA/gel matrix as the input. Importantly, the new colorimetric diagnostic approach does not require a priori knowledge on the exact metabolite compositions of the blood plasma, since the concept relies only on identifying statistically-significant changes in overall disease-induced chromatic response. The chromatic lipid/PDA/gel array-based “fingerprinting” concept is generic, easy to apply, and could be implemented for varied diagnostic and screening applications.

A calibration algorithm for nearfield scanning microwave microscopes

Abstract: This paper presents a new algorithm for the calibration of nearfield scanning microwave microscopes By adopting techniques known from vector network analyzer calibration, a nearfield scanning microwave microscope can be calibrated at a specific microwave frequency with three standards The advantages compared to existing calibration methods are that the calibration is valid for all possible samples and that the measurements require less time than other algorithms

Modeling of coupled spin torque oscillators for applications in associative memories

Abstract: This paper presents micromagnetic and circuit-level models describing the behavior of spin-torque oscillators (STOs). We demonstrate micromagnetic models that are in good agreement with experimental models for both individual and interconnected STOs and show that one can construct compact models based on the macrospin-approximation that match well with a full micromagnetic description. We study synchronization phenomena in various STOs, which are interconnected electrically or magnetically. The presented models can be used for studying complex networks of interconnected STOs. These networks may serve as hardware for oscillatory associative memories.

Iron oxide magnetic nanoparticles: A short review

Abstract: Magnetic nanoparticles have been enjoying great importance and wide scale applications during the last two decades due to their specific characteristics and applications. Iron oxide magnetic nanoparticles with appropriate surface chemistry have been implied in numerous applications such as biomedicine and cancer therapy, catalysis and in magnetic separation techniques. This review summarizes recent commercial, industrial and bio-engineering applications and brief study of the methods for the preparation of iron oxide magnetic nanoparticles with a control over the size, morphology and the magnetic properties. Some future applications of microwave irradiation for magnetic particle synthesis are also addressed.

Modelling and design of polygon-shaped kinesin substrates for molecular communication

Abstract: One of the most prominent forms of information transmission between nano- or micro-scale devices is molecular communication, where molecules are used to transfer information inside a fluidic channel. The effects of channel shape on achievable information transmission rates is considered in this work. Specifically, regular convex polygons are studied. A mathematical framework for finding the optimal channel among this class of geometric shapes is derived. Using this framework it is shown that the optimal channel tends to be circular. This result is verified using computer simulations.

ToPoliNano: A synthesis and simulation tool for NML circuits

Abstract: Many new emerging technologies are currently studied as possible substitute of CMOS transistors. Among these technologies one of the most interesting is the NanoMagnetic Logic (NML), which combines computation and memory in the same device. Although many works analyze this technology at the device level, an high level analysis on complex circuits is required to fully understand its potentialities. As an absolute novelty we present in this work a tool for automatic synthesis and simulation of NML circuits. Starting from a circuit described using VHDL language, the circuit physical layout is extracted, using all the technological constraints actually known. The circuit is then simulated using a behavioral model of the basic logic gates. This model is validated through micromagnetic low level simulations. Using ToPoliNano, which is highly modular and customizable, the possibility to explore and analyze realistic and complex NML circuits will be greatly improved.

Properties of Porous Asphalt Mixture Made with Styrene Butadiene Styrene under Long Term Oven Ageing

Abstract: Oven ageing is a set of procedure to simulate the accelerated effects of ageing on pavements structures. In this study, the effect of long-term oven ageing on porous asphalt mixture made with SBS modified binder was investigated. The resilient modulus, water permeability and air voids test results were the performance indicators used to evaluate the effects of ageing. The test results showed that, the resilient modulus of long term aged specimens was higher than those of unaged specimens. From the permeability test results, unaged SBS mixes exhibit lower coefficient permeability compared to the corresponding long-term oven age specimens. Most likely, ageing caused binder hardening, making the mix more difficult to compact and hence exhibited more continuous voids which in turn lead to higher permeability. In addition, the coefficient of permeability decreases as the binder content increased.

Development of the scratch resistance on acrylic sheet with basic colloidal silica (SiO2)—methyltrimethoxysilane (MTMS) nanocomposite films by sol–gel technique

Abstract: The formation of scratch-resistant coating film prepared from colloidal silica and a polysiloxane matrix was investigated. Methyltrimethoxysilane (MTMS) was hydrolysed and mixed with silica sol (SiO 2 ) at various compositions to form the hybrid hard-coating nanocomposite film. The hydrolysed MTMS (polysiloxane) acts as the polymeric binder that is covalently linked to the colloidal silica surface and provides adhesion for the scratch resistant coating film to the substrate. The ratio between the polymeric matrix and the SiO 2 nanoparticles was found to play a major role in controlling the coating film appearance and its resistance to scratching. At a Si0 2 content 70wt.%, there was not enough polysiloxane to act as a binder for the SiO 2 , therefore a shrinkage upon solidification of the coating film caused cracking within the nanocomposite film. The optimum ratio was found to be at 40 wt.% ≤SiO 2 <60wt.%, where the films had a transparent, crack free hard coating, with excellent scratch resistance, good adhesion and very good environmental resistance. The nanoindentation revealed that the nanocomposite film, at the optimum loading, possessed a higher strength with a higher SiO 2 loading. Film properties, including hardness, scratch resistance, adhesion and environmental resistance were also examined. The morphology of nanocomposite films was identified by atomic force microscopy (AFM) and scanning electron microscopy (SEM).

Resistive switching in copper oxide nanowire-based memristor

Abstract: A copper oxide nanowire (CuO NW) based memristor is designed for the non-volatile random access memories (NVRAM) and the resistive memory effect based transducers. The devices are prototyped using a copper oxide and cuprous oxide (CuO-Cu 2 O) hetero-junction formed from as-grown CuO NWs. We report an experimental investigation of using electron beam irradiation in fabricating such devices. Experiments have been performed using nanorobotic manipulation inside a transmission electron microscope. Because the memristor is conducted as a dynamical resistor, the bipolar resistive switching (BRS) behaviors of the as-fabricated device demonstrated typical ones of memristors. Furthermore, the as-fabricated nanowire memristor is sensitive to the electron bombardment. The irradiation ratio of NWs and the memristor effect are co-related, which is promising for the application in a transducer. The CuO NW based memristor will enrich the binary transition oxide family and holds a simpler design than the traditional thin-film version. Owing to these advantages, the CuO nanowire based memristors will facilitate their applications in nanoelectronic and potentially in micro-/nano-electromechanical systems (MEMS/NEMS).

Enabling nanoenergetic materials with integrated microelectronics and MEMS platforms

Abstract: This paper reports our findings in novel enabling high-energy-density nanostructured materials for micro-propulsion and other applications. In order to ensure the overall functionality, the system-level solution is achieved by integrating of synthesized nanoenergetic materials using microelectromechanical systems (MEMS). The MEMS solution provides high performance and enabling systems capabilities, while nanoenergetic materials guarantee safety, high stored energy capacity, high specific energy, stability, high energy and gas release rates, complete burning, etc. The system-level design and integration of self-assembled nanoenergetic materials by using MEMS imply development of NanoEnergetic MEMS Platforms. These systems have a wide range of applications, such as various explosives, propulsion systems, etc. The proposed nanoenergetic materials improve the overall power and energetic capabilities due to: 1. High stored energy, which reaches up to 25.7 kJ/cm3; 2. Ability to vary and refine properties of devised materials by adjusting molecular structure, enthalpy, stoichiometry, porosity and density; 3. Stability, compatibility, robust packaging and safety. Our studies indicate that the synthesized Al/Bi 2 O 3 and Al/I 2 O 5 nanocomposites ensure energy release and generate transient pressure impulses which are three times higher than traditional nano-thermite reactive mixtures. We address and provide systems-level design solutions solving integration, packaging, diagnostics, control and other problems

Determination of minimum conductivity of graphene from contactless microwaves measurements

Abstract: We report a non-direct method to determine the minimum conductivity (σ min ) of graphene. The proposed technique is based on the prior characterization of graphene sheet impedance at microwave frequencies using waveguides, and on the subsequent extraction of σ min from the measured scattering rate. This approach presents some advantages as compared with standard DC characterization methods, as it is inherently contactless and does not require graphene patterning. Our experimental study estimates a σ min in the range of 2e2/h-4e2/h for different samples. We also compute the density of charged impurities of our samples, and show that they are related to graphene conductivity at its Dirac point.

Molecule interaction for QCA computation

Abstract: Molecular Quantum-dot Cellular Automata (QCA) represent a new paradigm for nanoelectronics that seems to be very promising for digital computing. The elementary nano-device is a molecular system in which the binary encoding is provided by the charge localization within the molecule, without current flow. Basing on a previous analysis of a molecule synthesized ad-hoc for QCA technology, we discussed here the effect of the clock signal i) on a single molecule, ii) on the interaction between a driver and a molecule, and iii) on the interaction between two molecules. The results obtained by means of ab-initio calculations allowed to model a real QCA cell functional to a further study on the interaction between different cells‥

TAMTAMS: An open tool to understand nanoelectronics

Abstract: In order to assure the best learning experience, the teaching activity in Electronic Engineering is expected to closely follow the rapid evolution of CMOS technology. As a consequence the necessity of new teaching tools arises. These instruments must be flexible enough not only to follow technology evolution, but also to improve the learning experience by assuring interactivity and adaptability. In this work we present a tool “made by students for other students” which analyzes and compares different technologies from nanoscale CMOS transistors to emerging technologies, based for example on Carbon Nanotubes and Silicon Nanowires. The aim of this tool is to grant the students, but also the designers, with a useful instrument to understand the impact of scaling and of emerging technologies on nanoelectronics circuits. It allows the evaluation of different circuit parameters, from device level (currents, capacitances, …) to system level (power, speed, area, …). Since the best way to learn is “learning by doing”, the tool, based on the open source software GNU Octave, has a modular structure. In this way students not only can use it, but they can develop new modules starting from the literature, from teacher's experiences or from interesting case studies, contributing themselves to improve the learning experience of other students.

Synthesis of reversible circuits: A view on the state-of-the-art

Abstract: Four main approaches to synthesis of reversible circuits are considered: cycle-based, transformation-based, ESOP-based and BDD-based as well as their advantages and disadvantages are discussed It is indicated that the decisions in them are based on local information only what leads to very redundant designs Suggestions for making global decisions are also presented New directions of research are also described

Simultaneous switching noise and IR drop in graphene nanoribbon power distribution networks

Abstract: The work in this paper presents the analyses of simultaneous switching noise (SSN) and power supply voltage (IR drop) in graphene nanoribbon (GNR) interconnects for 16 nm technology node. The electrical equivalent model is used to derive the electrical circuit parameters for GNR interconnects. The results are compared with that of traditional copper (Cu) based interconnects. It has been found that the peak SSN in GNR is 41–23% less than that in Cu interconnects. The peak IR drop is 38–34% less in GNR as compared to Cu wires. The propagation delay is critically impacted due to SSN and IR drop. GNR shows up to 64.49% less impact in the delay in comparison to that of Cu based power networks.

Limitations of nanoparticle enhanced solder pastes for electronics assembly

Abstract: This paper reviews the limitations discovered recently in using nanoparticles to enhance solder pastes and discusses possible solutions to these problems. The motivation for introducing nanoparticles to reduce creep and excessive Intermetallic Compound (IMC) formation, especially for high temperature applications is first discussed. Next, the theoretical and practical limitations found for nanoparticle technology to enhance solder paste are given, together with possible solutions to these problems.

Transport in graphene on BN and SiC

Abstract: We study the mobility and high field velocity in graphene placed upon BN or SiC. The transport is subject to the intrinsic phonons in graphene, as well as flexural modes, remote polar modes from the BN or SiC and impurities sited between the BN layer and the underlying oxide.

Cellulose Nanofiber Composite Substrates for Flexible Electronics

Abstract: Flexible electronics have a large number of potential applications including malleable displays and wearable computers. The current research into high‐speed, flexible electronic substrates employs the use of plastics for the flexible substrate, but these plastics typically have drawbacks, such as high thermal expansion coefficients. Transparent films made from cellulose nanofibers have low thermal expansion and thus the potential to serve as substrates for flexible electronics. Here we present the results of using a cellulose nanofiber composite substrate for flexible electronics. While the initial processing procedures need improvement to reduce the film surface roughness and composite thermal expansion coefficient, a working prototype was built and is reported here.

Silver nanowire antenna printed on polymer and paper substrates

Abstract: Dramatic spread is going on high frequency operation device, such as mobile phones, wireless LAN, and radio frequency identification (RFID). Especially, the antenna is the most important element in the high-frequency operation device, and has been studied around the world. The printed antenna on flexible substrate is remarkable, since such printed antenna package is thinner, lighter and cheaper than conventional antenna prepared by etching process. In addition, printing process is a highly efficient and eco-friendly method.

Nitrogen doping of graphene nanoflakes by thermal plasma as catalyst for oxygen reduction in Proton Exchange Membrane fuel cells

Abstract: Proton Exchange Membrane fuel cells (PEMFCs) have two major hurdles to overcome before they may be commercially viable: cost and operating life. Platinum (Pt) catalyst represents the bulk of the PEMFC cost and is in finite supply, but functionalized carbon nanomaterials have been identified as potential replacements for Pt cathode catalyst. This work's objective is to produce graphene nanoflakes (GNFs) and dope them with nitrogen in pyridinic sites through a second treatment step. An inductively-coupled thermal plasma (ICP) is used to dissociate methane at very high temperatures, with GNF nucleation commencing shortly after by way of rapid quenching. In a post-treatment, nitrogen doping occurs by manipulating plasma conditions and nitrogen precursor selection. Nitrogen doping up to 33.4 at.% has been demonstrated which, to our knowledge, more than doubles the largest reported amount.

Transport characterization of a gated molecular device with negative differential resistance

Abstract: Due to increasing demand for advances in minimization, power consumption and speed of electronic devices, new technologies are emerging in order to replace/support the current semiconductor technology. Molecular electronics is one of the promising technologies that can offer an extreme increase in the integration density, since single molecules could be employed as active electronic devices. This theoretical paper deals with the transport characteristics of a gated molecular device, employing dithiolated Oligo-Phenylene Vinylene (OPV) molecules as testbed. The output current curves show a gate voltage dependency. In addition, a negative differential resistance (NDR) is observed. Transmission spectra, charge density distributions and potential profiles of the molecular device are provided to explain of the gate dependency and NDR behavior.

Surface potential variations in epitaxial graphene devices investigated by Electrostatic Force Spectroscopy

Abstract: Electrostatic Force Spectroscopy and Scanning Kelvin Probe Microscopy techniques are used to study the performance of side-gated Hall devices made of epitaxial graphene on 4H-SiC(0001). Electrostatic Force Spectroscopy is a novel method which allows quantitative surface potential measurements with high spatial resolution. Using these techniques, we calibrate work function of the metal coated tip and define the work functions for single and double-layer graphene. We also show that the use of moderate strength electrical fields in the side-gate geometry does not notably change the performance of the device.

Hybrid spintronic/straintronics: A super energy efficient computing scheme based on interacting multiferroic nanomagnets

Abstract: We have theoretically shown that multiferroic nanomagnets (consisting of a piezoelectric and a magnetostrictive layer) could be used to perform computing while dissipating ∼ few 100 kT/bit at clock rates of ∼1GHz [1,2,3]. They can act as memory elements [2], binary logic gates [3, 4] and associative memory for four state logic [5, 6]. The latter enables signal processing functions such as ultrafast image reconstruction and pattern recognition [7]. This talk will provide an overview of our research in modeling stress induced nanoscale magnetization dynamics, its application to ultra low energy hybrid spintronic/straintronics memory and information processing, and discuss preliminary experimental work in fabrication and experimental demonstration of these devices.

Low-power multiple-valued SRAM logic cells using single-electron devices

Abstract: This paper presents single electron tunneling (SET) based static memory cells for multiple-valued logic applications All simulations are conducted using Monte Carlo simulation tools In particular, a ternary SRAM cell is designed using the proposed architecture with standby power consumption of 098nW and logic margin of 270mV at temperature of 77K