Nanomaterials, such as metal or semiconductor nanoparticles and nanorods, exhibit similar dimensions to those of biomolecules, such as proteins (enzymes, antigens, antibodies) or DNA. The integration of nanoparticles, which exhibit unique electronic, photonic, and catalytic properties, with biomaterials, which display unique recognition, catalytic, and inhibition properties, yields novel hybrid nanobiomaterials of synergetic properties and functions. This review describes recent advances in the synthesis of biomolecule-nanoparticle/nanorod hybrid systems and the application of such assemblies in the generation of 2D and 3D ordered structures in solutions and on surfaces. Particular emphasis is directed to the use of biomolecule-nanoparticle (metallic or semiconductive) assemblies for bioanalytical applications and for the fabrication of bioelectronic devices.

Integrated Nanoparticle–Biomolecule Hybrid Systems: Synthesis, Properties, and Applications

“Spintronics,” in which both the spin and charge of electrons are used for logic and memory operations, promises an alternate route to traditional semiconductor electronics. A complete logic architecture can be constructed, which uses planar magnetic wires that are less than a micrometer in width. Logical NOT, logical AND, signal fan-out, and signal cross-over elements each have a simple geometric design, and they can be integrated together into one circuit. An additional element for data input allows information to be written to domain-wall logic circuits.

http://science.sciencemag.org/content/sci/309/5741/1688.full.pdf

Magnetic Domain-Wall Logic

The present invention provides stretchable, and optionally printable, semiconductors and electronic circuits capable of providing good performance when stretched, compressed, flexed or otherwise deformed. Stretchable semiconductors and electronic circuits of the present invention preferred for some applications are flexible, in addition to being stretchable, and thus are capable of significant elongation, flexing, bending or other deformation along one or more axes. Further, stretchable semiconductors and electronic circuits of the present invention may be adapted to a wide range of device configurations to provide fully flexible electronic and optoelectronic devices.

http://science.sciencemag.org/content/sci/311/5758/208.full.pdf

Stretchable form of single crystal silicon for high performance electronics on rubber substrates

Electron transport experiments on two lateral quantum dots coupled in series are reviewed. An introduction to the charge stability diagram is given in terms of the electrochemical potentials of both dots. Resonant tunneling experiments show that the double dot geometry allows for an accurate determination of the intrinsic lifetime of discrete energy states in quantum dots. The evolution of discrete energy levels in magnetic field is studied. The resolution allows one to resolve avoided crossings in the spectrum of a quantum dot. With microwave spectroscopy it is possible to probe the transition from ionic bonding (for weak interdot tunnel coupling) to covalent bonding (for strong interdot tunnel coupling) in a double dot artificial molecule. This review is motivated by the relevance of double quantum dot studies for realizing solid state quantum bits.

/pdf/electron-transport-through-double-quantum-dots-ppsjj6z4lk.pdf

Electron transport through double quantum dots

2.3. Medical Devices and Sensors 9 2.4. Radio Frequency Applications 10 3. Materials 12 3.1. Organic Electronics Materials 12 3.2. Semiconducting Polymer Design 13 3.3. Poly(3-alkylthiophenes) 14 3.4. Poly(thieno(3,2-b)thiophenes 15 3.5. Benchmark Polymer Semiconductors 15 3.6. High Performance Polymer Semiconductors 15 4. Device Stability 16 4.1. Bias Stress in Organic Transistors 17 4.1.1. Bias Stress Characterization 17 4.1.2. Bias Stress Mechanism 18 4.2. Short Channel Effects in Organic Transistors 19 5. Materials Patterning and Integration 20 6. Conclusions 22 7. Acknowledgments 22 8. References 22

Materials and applications for large area electronics: solution-based approaches.

A functioning logic gate based on quantum-dot cellular automata is presented, where digital data are encoded in the positions of only two electrons. The logic gate consists of a cell, composed of four dots connected in a ring by tunnel junctions, and two single-dot electrometers. The device is operated by applying inputs to the gates of the cell. The logic AND and OR operations are verified using the electrometer outputs. Theoretical simulations of the logic gate output characteristics are in excellent agreement with experiment.

/pdf/digital-logic-gate-using-quantum-dot-cellular-automata-1vdvc261qr.pdf

Digital logic gate using quantum-Dot cellular automata

This paper presents an experimental demonstration of a basic cell of the quantum-dot cellular automata, a transistorless approach to computation that addresses the issues of device density, interconnection, and power dissipation. The device under study was composed of four metal dots, connected with tunnel junctions and capacitors, and operated at <50 mK. Operation was evidenced by switching of a single electron between output dots controlled by a single electron switching in input dots, demonstrating a nonlinear, bistable response.

/pdf/realization-of-a-functional-cell-for-quantum-dot-cellular-li4t4lve6n.pdf

Realization of a Functional Cell for Quantum-Dot Cellular Automata

The recent surge of interest in nanomaterials is driven by not only the need of ever-increasing miniaturization of microelectronics but also the discovery of many novel phenomena that occur on the nanoscale. 1 Conducting polymers are attractive for a variety of applications. 2 Bulk polymer materials are often described as highly conductive nanocrystalline domains separated with less conductive disordered regions. 3 The inhomogeneity has been a serious hindrance for a complete understanding of the materials as well as for many applications. To date, most works have focused on bulk samples, which measure properties averaged out over many nanocrystalline domains and disordered regions. Because nanocystalline domains are as small as a few nanometers, directly probing each individual domains is not a trivial task. In this communication, we report a study of charge transport through a polyaniline nanojunction formed between two nanoelectrodes separated with a gap comparable to the size of a nanocrystalline domain. In sharp contrast to bulk samples whose conductance varies smoothly between insulating and conducting states as a function of the electrochemical potential, the polymer nanojunction switchesabruptly between the two states, in the fashion of a digital switch. The nanojunction can switch much faster with less power than larger junctions, and may be exploited in sensor applications. Wrighton et al. 4 have pioneered a conducting polymer microelectrochemical transistor to measure the electrical properties of polymer materials between two microfabricated electrodes by controlling the electrochemical potential of the electrodes. A crucial task of our experiment is to fabricate a pair of nanoelectrodes with a gap of a few nanometers or less, which is achieved using two methods. The first method 5 starts with a pair of Au nanoelectrodes with a 20 -80 nm gap on an oxidized Si substrate by electron beam lithography. We then further reduce the gap by electrochemically depositing Au onto the nanoelectrodes, using the tunneling current between the nanoelectrodes as feedback. The closest distance between the nanoelectrodes is ∼1 nm, estimated from the tunneling current, and the radius of curvature of each nanoelectrode is between 5 and 15 nm (Figure 1). The second method uses a STM setup, 6 which can produce similar results but is more susceptible to drift. After forming a small gap, we deposit polyaniline onto the nanoelectrodes by sweeping the electrochemical potential between 0.15 and 0.75 V (vs Ag/AgCl) in 30 mM aniline + 0.5 M Na2SO4 (pH 1).7 When the growing polyaniline bridges the gap, the current increases sharply across the gap, which prompts an immediate stop of the deposition process. We then replace the aniline solution with bare supporting electrolyte and study the conductance of the polyaniline nanojunction as a function of electrochemical potential. For relatively large junctions in which polyaniline is sandwiched between two nanoelectrodes separated with 20 -80 nm gap, the current increases smoothly and reaches a maximum near 0.4 V, as the polymer is switched from insulating to conducting states (Figure 2). Although the polymer can be reversibly switched between conducting and insulating states, a large hysteresis is apparent, which has been attributed to structural relaxations. 8

A conducting polymer nanojunction switch.

Experimental studies are presented of a binary wire based on the quantum-dot cellular automata computational paradigm. The binary wire consists of capacitively coupled double-dot cells charged with single electrons. The polarization switch caused by an applied input signal in one cell leads to the change in polarization of the adjacent cell and so on down the line, as in falling dominos. Wire polarization was measured using single islands as electrometers. Experimental results are in very good agreement with the theory and confirm there are no metastable states in the wire.

/pdf/experimental-demonstration-of-a-binary-wire-for-quantum-dot-26n00zkhk0.pdf

Experimental demonstration of a binary wire for quantum-dot cellular automata

Single-wall carbon nanotubes (SWNTs) suspended in an aqueous solution have been placed selectively between two metal electrodes separated by a few tens of nanometers. After the initial patterning of the metal electrodes by electron beam lithography, no further fine-line lithography steps are necessary to achieve directed placement of SWNTs at these dimensions. An ac bias is applied between the two electrodes and the “nanoscale wiring” is completed within seconds. An additional advantage of using ac bias is the enhancement for selectively placing SWNTs between the electrode gap over competing contaminant species in the solution.

Islamshah Amlani

Papers

Digital logic gate using quantum-Dot cellular automata

Realization of a Functional Cell for Quantum-Dot Cellular Automata

A conducting polymer nanojunction switch.

Experimental demonstration of a binary wire for quantum-dot cellular automata

Directed placement of suspended carbon nanotubes for nanometer-scale assembly