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We introduce silicene, the Si-based analog of graphene, an emerging two-dimensional topological insulator, and its realization by epitaxial growth on the favored silver (111) substrate. We describe the structural, electronic and vibronic properties of monolayer silicene, and the growth and electronic properties of multilayer silicene. We next address the hydrogenation and oxidation of these new silicon allotropes. We further report the fabrication of the first field-effect transistors made with a silicene channel. Finally, we discuss exotic forms of silicon at zero and one dimension, namely benzene-like nanodots and pentasilicene-like nanoribbons, before drawing enticing perspectives.

We acknowledge financial support from the Scottish Funding Council (through EaStCHEM and SRD-Grant HR07003) and from EPSRC (PhD studentship for JAGT, EP/M506631/1). Computational support was provided via the EaStCHEM Research Computing Facility. Modern electronic devices perform their defined action because of the complete reliability of their individual active components (transistors, switches, diodes, and so forth). For instance, to encode basic computer units (bits) an electrical switch can be used. The reliability of the switch ensures that the desired outcome (the component’s final state, 0 or 1) can be selected with certainty. No practical data storage device would otherwise exist. This reliability criterion will necessarily need to hold true for future molecular electronics to have the opportunity to emerge as a viable miniaturization alternative to our current silicon-based technology. Molecular electronics target the use of single-molecules to perform the actions of individual electronic components. On-demand final state control over a bistable unimolecular component has therefore been one of the main challenges in the past decade (1−5) but has yet to be achieved. In this Letter, we demonstrate how control of the final state of a surface-supported bistable single molecule switch can be realized. On the basis of the observations and deductions presented here, we further suggest an alternative strategy to achieve final state control in unimolecular bistable switches. Postprint Postprint

Electrical signals emanating from biological cells can convey clinical information on the functionality thereof. However, measurement of such small signals caused primarily by ionic activity inside the cell, known as action potential, poses a great challenge to biomedical scientists. The electrical signals of the biological cells result from exchange of ions through the cell membrane. The characteristics of action potentials may reveal a great deal of information about the causes and symptoms of abnormal cell behaviour. Hence, it is imperative to capture high quality action potentials through the use of nano-sensors from within the cell. Recently, developments in silicon nanowires (SiNW) fabrication techniques have demonstrated a great potential for them to be used as nano-electrodes. Largescale assembly and integration of addressable complementary silicon nanowires arrays have been demonstrated for multiplexed biosensor arrays. The fabrication process resulted in a high-yield, high performance devices arrays for chemical and biological detection. In this paper, we seek to model the electrical interface that is responsible for recording the biological signals. We present electrical equivalent circuits that model the boundary between the biological cell and the nanowire electrode. Impedance measurement curves of nanowires for various sizes of length and diameter have also been presented and discussed. The impedance graphs show a hyperbolic dependence of resistance on length and diameter of nanowires. This non-linear behaviour may be mitigated in software algorithms when interpreting the measured cell signals. Refereed/Peer-reviewed

Research in recent years has greatly advanced the understanding and capabilities of multi-beam interference (MBI). With this technology it is now possible to generate a wide range of one-, two-, and three-dimensional periodic optical-intensity distributions at the micro- and nano-scale over a large length/area/volume. These patterns may be used directly or recorded in photo-sensitive materials using multi-beam interference lithography (MBIL) to accomplish subwavelength patterning. Advances in MBI and MBIL and a very wide range of applications areas including nano-electronics, photonic crystals, metamaterials, subwavelength structures, optical trapping, and biomedical structures are reviewed and put into a unified perspective.

This study examines the radical nature and spin symmetry of the ground state and low-lying ionic states of the quasi-linear acene and two-dimensional periacene series. For this purpose, high-level ab initio calculations have been performed using the multireference averaged quadratic coupled cluster theory and the COLUMBUS program package. A complete active space (CAS) approach is taken for the π-conjugated space, correlating 16 electrons in 16 orbitals with the most open-shell character for the acenes and a similar approach with 8 electrons in 8 orbitals for the periacenes. For the ground state it is shown that a focus on the π space with a 6-31G basis set is sufficient to describe the major features of the electronic character of these compounds. The findings of this treatment suggest that the ground state is a singlet for the smaller members of these series, but that for the larger ones singlet and triplet states are quasi-degenerate. Both the acenes and periacenes exhibit significant polyradical character beyond the traditional diradical. However, for the low-lying ionic states, the π space with a 6-31G basis is found to be insufficient in describing the major features of the electronic character of these compounds. Accordingly, an all valence calculation is made with extended basis sets to include polarized and diffuse functions. The findings of this treatment suggest that all members of the acene and periacene series are bound except for naphthalene, which agrees with experiment. All ions for both the acenes and periacenes exhibit a significant decrease in radical character as compared to the neutral state.

This paper focuses on the opportunities offered by the latest advances in silicon technologies for realizing system-on-chip microwave radiometer. Such a highly integrated, low-cost, radiometer chip could be applied to the environmental remote sensing and, in particular, to the forest fire detection. The feasibility study is carried-out in two steps. First, a proof of the concept is given by means of a discrete-component radiometer operating at 12.65 GHz. This radiometer exploits TV-SAT components such as low-noise down-converter and dish antenna. On-field measurements shows a radiometric contrast (increase of the antenna noise temperature due to the fire with respect to the background) of about 8 K for a wooden fire of 0.38 m 2 placed 30 m away from the antenna. Then, a single-chip 13 GHz radiometer has been designed exploiting a CMOS 90 nm standard process. The sensor is based on a direct-conversion architecture with integrated LNA, Gilbertpsilas cell mixer and PLL frequency synthesizer. The IF chain includes an active (gm-C) low-pass filter and a CMOS square-law detector. The circuit simulations show a total receiver gain of 72 dB, an equivalent input noise temperature of 105 K and an IF bandwidth of 100 MHz.

This paper deals with the effects of faults on circuits implemented with controllable-polarity transistors. We propose a new fault model that suits the characteristics of these devices, and report the results of a SPICE-based analysis of the effects of faults on the behavior of some basic gates implemented with them. Hence, we show that the considered devices are able to intrinsically tolerate a rather high number of faults. We finally exploit this property to build a robust and scalable adder which is shown to tolerate all single faults and more than 99.5% of the double faults. Its area, performance and leakage power characteristics are improved by 15%, 18% and 12%, respectively, when compared to an equivalent FinFET solution at 22-nm technology node.

We combine optical microspectroscopy and electronic measurements to study how gold deposition affects the physical properties of graphene. We find that the electronic structure, the electron-phonon coupling, and the doping level in gold-plated graphene are largely preserved. The transfer lengths for electrons and holes at the graphene gold contact have values as high as 1.6 mu m. However, the interfacial coupling of graphene and gold causes local temperature drops of up to 500 K in operating electronic devices.

The paper reports the present status of the project aimed at the realization of a wearable low-cost low-power System-on-Chip (SoC) 13-GHz passive microwave radiometer in CMOS 90 nm technology. This sensor has been thought to be inserted into the firemen jacket in order to help them in the detection of a hidden fire behind a door or a wall, especially where the IR technology fail. With respect of the prior art, the SoC is further developed and a proof of the concept is provided by means of a discrete-component prototype.