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Recent progress in the on-surface synthesis and characterization of nanomaterials is facilitating the realization of new carbon allotropes, such as nanoporous graphenes, graphynes, and 2D π-conjugated polymers. One of the latest examples is the biphenylene network (BPN), which was recently fabricated on gold and characterized with atomic precision. This gapless 2D organic material presents uncommon metallic conduction, which could help develop innovative carbon-based electronics. Here, using first principles calculations and quantum transport simulations, we provide new insights into some fundamental properties of BPN, which are key for its further technological exploitation. We predict that BPN hosts an unprecedented spin-polarized multiradical ground state, which has important implications for the chemical reactivity of the 2D material under practical use conditions. The associated electronic band gap is highly sensitive to perturbations, as seen in finite temperature (300 K) molecular dynamics simulations, but the multiradical character remains stable. Furthermore, BPN is found to host in-plane anisotropic (spin-polarized) electrical transport, rooted in its intrinsic structural features, which suggests potential device functionality of interest for both nanoelectronics and spintronics., I.A. is grateful for a Juan de la Cierva postdoctoral grant (FJC2019-038971-I) from the Spanish Ministerio de Ciencia e Innovación. Financial support by Villum Fonden (00013340) is gratefully acknowledged. ICN2 is funded by the CERCA Programme from Generalitat de Catalunya and is supported by the Severo Ochoa program from Spanish MINECO (grant no. SEV-2017-0706). The Center for Nanostructured Graphene (CNG) is sponsored by the Danish National Research Foundation (DNRF103). S.R. acknowledges funding from the European Union Seventh Framework Programme under grant no. 881603 (Graphene Flagship).

We study by scanning thermal microscopy the nanoscale thermal conductance of films (40-400 nm thick) of [1]benzothieno[3,2-b][1]benzothiophene (BTBT) and 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT-C8). We demonstrate that the out-of-plane thermal conductivity is significant along the interlayer direction, larger for BTBT (0.63 ± 0.12 W m-1 K-1) compared to C8-BTBT-C8 (0.25 ± 0.13 W m-1 K-1). These results are supported by molecular dynamics calculations (approach to equilibrium molecular dynamics method) performed on the corresponding molecular crystals. The calculations point to significant thermal conductivity (3D-like) values along the 3 crystalline directions, with anisotropy factors between the crystalline directions below 1.8 for BTBT and below 2.8 for C8-BTBT-C8, in deep contrast with the charge transport properties featuring a two-dimensional character for these materials. In agreement with the experiments, the calculations yield larger values in BTBT compared to C8-BTBT-C8 (0.6-1.3 W m-1 K-1versus 0.3-0.7 W m-1 K-1, respectively). The weak thickness dependence of the nanoscale thermal resistance is in agreement with a simple analytical model. This journal is, M. G., D. G., S. L. and D. V. thank the ANR for financial support (ANR-16-CE05-0029). Y. G. is thankful to the Belgian National Fund for Scientific Research (FNRS) for financial support through research projects BTBT (# 2.4565.11), Phasetrans (# T.0058.14), Pi-Fast (# T.0072.18), 2D to 3D (# 30489208), and DIFFRA (# U.G001.19). Financial supports from the French Community of Belgian (ARC # 20061) is also acknowledged. G. S. acknowledges postdoctoral fellowship support from the FNRS. The work in the Laboratory for Chemistry of Novel Materials was supported by the Consortium des Équipements de Calcul Intensif (CÉCI), funded by the Fonds de la Recherche Scientifique de Belgique (F.R.S.-FNRS) under grant # 2.5020.11. J.C. and A.V. are FNRS research fellows.

In the context of graphene-based composite applications, a complete understanding of charge conduction in multilayer reduced graphene oxides (rGO) is highly desirable. However, these rGO compounds are characterized by multiple and different sources of disorder depending on the chemical method used for their synthesis. Most importantly, the precise role of interlayer interaction in promoting or jeopardizing electronic flow remains unclear. Here, thanks to the development of a multiscale computational approach combining first-principles calculations with large-scale transport simulations, the transport scaling laws in multilayer rGO are unraveled, explaining why diffusion worsens with increasing film thickness. In contrast, contacted films are found to exhibit an opposite trend when the mean free path becomes shorter than the channel length, since conduction becomes predominantly driven by interlayer hopping. These predictions are favorably compared with experimental data and open a road toward the optimization of graphene-based composites with improved electrical conduction., The authors acknowledge support from the Flag-Era JTC 2017 project ‘ModElling Charge and Heat trANsport in 2D-materIals based Composites ─ MECHANIC’. M.N.Ç. and H.S. acknowledge support from TÜBİTAK (117F480). The numerical calculations reported in this paper were partially performed at TÜBİTAK ULAKBİM, High Performance and Grid Computing Center (TRUBA resources). A.A. and S.R. are supported by MECHANIC reference number: PCI2018-093120 funded by Ministerio de Ciencia, Innovacion y Universidades and the European Union Horizon 2020 research and innovation programme under Grant Agreement No. 881603 (Graphene Flagship). ICN2 is funded by the CERCA Programme/Generalitat de Catalunya, and is supported by the Severo Ochoa program from Spanish MINECO (Grant No. SEV-2017-0706). V.-H.N. and J.-C.C. acknowledge financial support from the Fédération Wallonie-Bruxelles through the ARC Grants (No. 16/21-077 and No. 21/26-116), from the European Union’s Horizon 2020 Research Project and Innovation Program ─ Graphene Flagship Core3 (No. 881603), from the Flag-ERA project (No. R.8010.19), and from the Belgium FNRS through the research projects (No. T.0051.18 and No. T.029.22F). Computational resources have been provided by the CISM supercomputing facilities of UCLouvain and the CECI consortium funded by F.R.S. -FNRS of Belgium (No. 2.5020.11). Computational resources have been provided by the CISM supercomputing facilities of UCLouvain and the CECI consortium funded by F.R.S. -FNRS of Belgium (No. 2.5020.11).

We report on a large improvement of the thermal stability and mechanical properties of amorphous boron-nitride upon carbon doping. By generating versatile force fields using first-principles and machine learning simulations, we investigate the structural properties of amorphous boron-nitride with varying contents of carbon (from a few percent to 40 at%). We found that for 20 at% of carbon, the sp/sp ratio reaches a maximum with a negligible graphitisation effect, resulting in an improvement of the thermal stability by up to 20% while the bulk Young's modulus increases by about 30%. These results provide a guide to experimentalists and engineers to further tailor the growth conditions of BN-based compounds as non-conductive diffusion barriers and ultralow dielectric coefficient materials for a number of applications including interconnect technology., This project has been supported by Samsung Advanced Institute of Technology and is conducted under the REDI Program, a project that has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 101034328. ICN2 acknowledges the Grant PCI2021-122092-2A funded by MCIN/AEI/10.13039/501100011033 and by the “European Union NextGenerationEU/PRTR”. Simulations were performed at the Center for Nanoscale Materials, a U.S. Department of Energy Office of Science User Facility, supported by the U.S. DOE, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

We review recent developments on the synthesis and properties of two-dimensional materials which, although being mainly of an sp bonding character, exhibit highly disordered, non-uniform and structurally random morphologies. The emergence of such class of amorphous materials, including amorphous graphene and boron nitride, have shown superior properties compared to their crystalline counterparts when used as interfacial films. In this paper we discuss their structural, vibrational and electronic properties and present a perspective of their use for electronic applications., AA and SR are supported by ModElling Charge and Heat trANsport in 2D-materIals based Composites - MECHANIC reference number: PCI2018-093120 funded by Ministerio de Ciencia, Innovación y Universidades and the European Union Horizon 2020 research and innovation programme under Grant Agreement No. 881603 (Graphene Flagship). ICN2 is funded by the CERCA Programme/Generalitat de Catalunya, and is supported by the Severo Ochoa program from Spanish MINECO (Grant No. SEV-2017-0706).

We thank UNIST Central Research Facilities (UCRF) and Y. K. Kim for the cross-sectional high-resolution TEM images. This work was supported by Samsung Electronics (Samsung-SKKU Graphene/2D Center), the research fund (NRF-2017R1E1A1A01074493 and NRF-2019R1A4A1027934), the IBS (IBS-R-019-D1) and a grant (CASE-2013M3A6A5073173) from the Centre for Advanced Soft Electronics under the Global Frontier Research Program via the National Research Foundation of the Ministry of Science and ICT, South Korea. The NEXAFS experiments performed at the 4D, 6D and 10A2 beamlines of the Pohang Accelerator Laboratory (PAL) were supported in part by the Ministry of Science and ICT, POSTECH and UNIST. M.C. acknowledges support from Leverhulme Trust Research Grant RPG-2019-227. S.R., A.A. and M.C. acknowledge the European Union Horizon 2020 research and innovation programme for grant number 785219 and 881603 (Graphene Flagship). A.A. is supported by Project MECHANIC (PCI2018-093120) funded by Ministerio de Ciencia, Innovación y Universidades. The Catalan Institute of Nanoscience and Nanotechnology is funded by the CERCA Programme/Generalitat de Catalunya and supported by the Severo Ochoa Centres of Excellence programme, funded by the Spanish Research Agency (grant number SEV-2017-0706).

This work was supported by Samsung Electronics (Samsung-SKKU Graphene/2D Center) and the research fund (NRF-2017R1E1A1A01074493 and NRF-2019R1A4A1027934) through the National Research Foundation by the Ministry of Science and ICT, Korea. M.C. acknowledges support from Leverhulme Trust Research grant RPG-2019-227.

Funder: Consortium des Équipements de Calcul Intensif, Funder: The Leverhulme Trust, While the charge transport properties of organic semiconductors have been extensively studied over the recent years, the field of organics‐based thermoelectrics is still limited by a lack of experimental data on thermal transport and of understanding of the associated structure–property relationships. To fill this gap, a comprehensive experimental and theoretical investigation of the lattice thermal conductivity in polycrystalline thin films of dinaphtho[2,3‐b:2′,3′‐f]thieno[3,2‐b]thiophene (Cn‐DNTT‐Cn with n = 0, 8) semiconductors is reported. Strikingly, thermal conductivity appears to be much more isotropic than charge transport, which is confined to the 2D molecular layers. A direct comparison between experimental measurements (3ω–Völklein method) and theoretical estimations (approach‐to‐equilibrium molecular dynamics (AEMD) method) indicates that the in‐plane thermal conductivity is strongly reduced in the presence of the long terminal alkyl chains. This evolution can be rationalized by the strong localization of the intermolecular vibrational modes in C8‐DNTT‐C8 in comparison to unsubstituted DNTT cores, as evidenced by a vibrational mode analysis. Combined with the enhanced charge transport properties of alkylated DNTT systems, this opens the possibility to decouple electron and phonon transport in these materials, which provides great potential for enhancing the thermoelectric figure of merit ZT.

Among its many uses, graphene shows significant promise for optical and optoelectronic applications. In particular, devices based on the photothermoelectric effect (PTE) in graphene can offer a strong and fast photoresponse with a high signal-to-noise ratio while consuming minimal power. In this work, we discuss how to optimize the performance of graphene PTE photodetectors by tuning the light confinement, device geometry, and material quality. This study should prove useful for the design of devices using the PTE in graphene, with applications including optical sensing, data communications, multigas sensing, and others., ICN2 is supported by the Severo Ochoa Centres of Excellence program, funded by the Spanish State Research Agency (AEI, Grant No. SEV-2017-0706), and is funded by the CERCA program of the Generalitat de Catalunya. This work has received funding from the European Union's Horizon 2020 research and innovation program under Grant Agreement No. 825272 (ULISSES) and from the project “Waveguide-Integrated Mid-Infrared Graphene Detectors for Optical Gas Sensor Systems,” Reference No. PCI2018-093128, funded by the Spanish Ministry of Science and Innovation - AEI.

Networks based on nanoscale resistive switching junctions are considered promising for the fabrication of neuromorphic computing architectures. To date random networks of nanowires, nanoparticles, and metal clusters embedded in a polymeric matrix or passivated by shell of ligands or oxide layers have been used to produce resistive switching systems. The strategies applied to tailor resistive switching behavior are currently based on the careful control of the volume fraction of the nanoscale conducting phase that must be fixed close to the electrical percolation threshold. Here, by blending laboratory and computer experiments, we demonstrate that metallic nanostructured Au films fabricated by bare gold nanoparticles produced in the gas phase and with thickness well beyond the electrical percolation threshold, show a non-ohmic electrical behavior and complex and reproducible resistive switching. We observe that the nanogranular structure of the Au films does not evolve with thickness: this introduces a huge number of defects and junctions affecting the electrical transport and causing a dynamic evolution of the nanoscale electrical contacts under the current flow. To uncover the origin of the resistive switching behavior in Au cluster-assembled films, we developed a simple computational model for determining the evolution of a model granular film under bias conditions. The model exploits the information provided by experimental investigation about the nanoscale granular morphology of real films. Our results show that metallic nanogranular materials have functional properties radically different from their bulk counterparts, in particular nanostructured Au films can be fabricated by assembling bare gold clusters which retain their individuality to produce an all-metal resistive switching system.

Advanced data encryption requires the use of true random number generators (TRNGs) to produce unpredictable sequences of bits. TRNG circuits with high degree of randomness and low power consumption may be fabricated by using the random telegraph noise (RTN) current signals produced by polarized metal/insulator/metal (MIM) devices as entropy source. However, the RTN signals produced by MIM devices made of traditional insulators, i.e., transition metal oxides like HfO and AlO, are not stable enough due to the formation and lateral expansion of defect clusters, resulting in undesired current fluctuations and the disappearance of the RTN effect. Here, the fabrication of highly stable TRNG circuits with low power consumption, high degree of randomness (even for a long string of 2 − 1 bits), and high throughput of 1 Mbit s by using MIM devices made of multilayer hexagonal boron nitride (h-BN) is shown. Their application is also demonstrated to produce one-time passwords, which is ideal for the internet-of-everything. The superior stability of the h-BN-based TRNG is related to the presence of few-atoms-wide defects embedded within the layered and crystalline structure of the h-BN stack, which produces a confinement effect that avoids their lateral expansion and results in stable operation., M.L. acknowledges generous support from the King Abdullah University of Science and Technology. This work was supported by the Ministry of Science and Technology of China (grants no. 2018YFE0100800, 2019YFE0124200), the National Natural Science Foundation of China (grants no. 61874075), the Collaborative Innovation Centre of Suzhou Nano Science & Technology, the Priority Academic Program Development of Jiangsu Higher Education Institutions, and the 111 Project from the State Administration of Foreign Experts Affairs of China. A.A. and S.R. acknowledge the project: ModElling Charge and Heat trANsport in 2D-materIals based Composites—MECHANIC reference number: PCI2018-093120 funded by Ministerio de Ciencia, Innovación y Universidades. ICN2 is funded by the CERCA Programme/Generalitat de Catalunya and is supported by the Severo Ochoa program from Spanish MINECO (Grant No. SEV-2017-0706). Y.S. acknowledges support from the European Union (Marie Sklodowska-Curie actions (grant no. 894840). The authors acknowledge technical advice from H.-S. Philip Wong from Stanford University and Xiaoming Xie from Chinese Academy of Sciences.

In this work we study the effect of different synthetic conditions on thermal transport properties of poly(3,4-ethylenedioxythiophene) (PEDOT) by focusing in particular on the role of proton scavengers. To this aim, different PEDOT samples were generated in silico using a novel computational algorithm based on a combination of first-principles density functional theory and classical molecular dynamics simulations. The corresponding thermal conductivities were then estimated using the approach to equilibrium molecular dynamics methodology. The results show that the initial synthetic conditions strongly affect the corresponding thermal conductivities, which display variations up to a factor of $\ensuremath{\sim}2$ depending on the proton scavenger. By decomposing the thermal conductivity tensor along the direction of maximum chain alignment and the corresponding perpendicular directions, we attribute the thermal conductivity differences to the variations in the average polymer chain length ${\ensuremath{\lambda}}_{\mathrm{ave}}$. A dependence of the thermal conductivity with the polydispersity index was finally observed, suggesting a possible role of intercrystallite chains in enhancing thermal transport properties. By means of the Green-Kubo modal analysis, we eventually characterize the vibrational modes involved in PEDOT thermal transport and investigate how they are related to the thermal conductivity values of the samples.

The synthesis of wafer-scale two-dimensional amorphous carbon monolayers has been recently demonstrated. This material presents useful properties when integrated as coating of metals, semiconductors or magnetic materials, such as enabling efficient atomic layer deposition and hence fostering the development of ultracompact technologies. Here we propose a characterization of how the structural degree of amorphousness of such carbon membranes could be controlled by the crystal growth temperature. We also identify how energy is dissipated in this material by a systematic analysis of emerging vibrational modes whose localization increases with the loss of spatial symmetries, resulting in a tunable thermal conductivity varying by more than two orders of magnitude. Our simulations provide some recipe to design most suitable 'amorphous graphene' based on the target applications such as ultrathin heat spreaders, energy harvesters or insulating thermal barriers., The authors acknowledge the project: ModElling Charge and Heat trANsport in 2D-materIals based Composites—MECHANIC reference number: PCI2018-093120 funded by Ministerio de Ciencia, Innovacion y Universidades. ICN2 is funded by the CERCA Programme/Generalitat de Catalunya and is supported by the Severo Ochoa program from Spanish MINECO (Grant No. SEV-2017-0706).

Owing to its array of unique properties, graphene is a promising material for a wide variety of applications. Being two-dimensional, the properties of graphene are also easily tuned via proximity to other materials. In this work, we investigate the possibility of inducing electrical and optical anisotropy in graphene by interfacing it with other anisotropic carbon systems, including nanoporous graphene and arrays of graphene nanoribbons. We find that such materials do indeed induce such anisotropy in graphene while also preserving the unique properties offered by graphene's Dirac band structure, namely, its superior charge transport and long-wavelength optical absorption. The optical anisotropy makes such heterostructures interesting for their use in applications related to long-wavelength polarimetry, while the electrical anisotropy may be valuable for enhancing the performance of graphene photothermoelectric detectors., ICN2 is supported by the Severo Ochoa Centers of Excellence Program, funded by the Spanish State Research Agency (AEI, Grant No. SEV-2017-0706). ICN2 is also supported by the CERCA Program of the Generalitat de Catalunya. This work received funding from the European Union’s Horizon 2020 Research and Innovation Program under Grant Agreement No. 825272 (ULISSES) and from the project “Waveguide-Integrated Mid-Infrared Graphene Detectors for Optical Gas Sensor Systems,” Reference No. PCI2018-093128, funded by the Spanish Ministry of Science and Innovation—AEI.

The organic/inorganic interface in thin nanosized porous structures has a key role in determining the final properties of the composite materials. By use of the porous silicon/eumelanin hybrids as a case study, the role of this interface was investigated by experimental and computational methods. Our results show that an increased polymer density close to the hybrid interface strongly modifies the diffusion of the chemical species within the polymer molecule, affecting then the oxidation level of the pores' inner Si surface. We observed a greater stability induced by increased pore diameter, a behavior that with computational and chemical arguments we attributed to a modified diffusion of the hydrogen peroxide toward the Si/eumelanin interface. Our results show that the overall behavior of a polymer when inserted in a tiny nanoscale structure must be taken into account for a correct understanding and control of the hybrids properties and that the formation of the interface alone may not be sufficient. © 2018 American Chemical Society.

We present thermal and electron transport calculations in the ballistic regime of a graphene nanoribbon with a nanogap bridged by a stilbene molecular switch. We show that by commuting the stilbene molecule back and forth between its two stable isomers, the thermal conductance can be reversibly switched from a low to a high conduction state, providing a proof-of-concept of a molecular junction-based thermal switch.

Micromorphology of conjugated polymers is expected to play a crucial role in both heat and charge transport properties. In this perspective, the details of the polymerization mechanism acquire a fundamental relevance, providing the link between the basic chemical reaction paths and the resulting molecular structure and arrangement. For PEDOT, the role played by the Bronsted bases (proton scavengers) and their impact on the distribution of polymer chain lengths are still a matter of debate. In the present work, we have systematically analyzed several reaction paths leading to PEDOT polymerization. By means of atomistic simulations, we identified the thermodynamically preferred reaction path, proving that tosylate anions rule proton scavenging. PEDOT chain length was computed to be ∼12-13 monomeric units. We could also demonstrate how the proton scavengers set at once the chain lengths and the sample crystallinity. Furthermore, we found that tosylate gives rise to a sharper multimodal distribution of chain length, a feature that supports hypotheses regarding the occurrence of a percolative transport regime mediated by tie chains bridging paracrystalline regions.

We performed a systematic analysis of the vibrational modes in nanoporous silicon for different values of porosity, separating them into extended modes (diffusons and propagons) and localized vibrations (locons). By calculating the density of states, the participation ratio, and the systems' dispersion curves, the spatial character of each mode as well as the effect of porosity on the thermal conductivity have been investigated. An increase of porosity is shown to promote the existence of increasingly localized modes on one side, and the progressive transformation of propagons to diffusons on the other. Finally, we provide evidence of the sizable contribution of locons to thermal transport found in large porosity samples and discuss the mechanism of energy transfer in terms of mode-mode autocorrelations and cross-correlations.

We present and discuss a computational setup aimed at modeling the polymerization process of eumelanin by combining together molecular dynamics simulations and ab initio total-energy calculations. By simulating the oxidative polymerization process of eumelanin in methanol, we provide evidence that “in silico” synthesized samples are mostly composed of low-molecular-weight structures: an exponential distribution of the molecular weights is found, yielding an average weight less than 10. Adopting the scheme of chemical disorder, we also perform a statistical analysis on the variety of molecules formed, focusing on both their structural and electronic features. In particular, we identify the most frequent structural patterns within the molecules by analyzing the occurrence of the single chemical bonds. Moreover, we show how most of the molecules have a large number of nonterminated oxygen atoms, highlighting the pivotal role of =O groups in the eumelanin molecular stability., We acknowledge the Regione Sardegna basic research Project no. CRP78744 “Energy Applications with Porous Silicon (ENAPSi).” E.C. acknowledges support from MINECO (Spain) (Grant FIS2015-64886-C5-4-P), the Severo Ochoa Centers of Excellence Program (Grant SEV-2015-0496), and Generalitat de Catalunya (2017SGR1506).

Among the possible applications of eumelanin (biolelectronics, biointerfaces, etc.), photovoltaics is a promising field which could highly benefit from its intrinsic features (broadband UV–vis absorption, etc.), with such a pigment employed as photoactive layer in hybrid solar cells. The envisioned application poses the need for a careful theoretical analysis on the adhesion properties of eumelanin on a substrate and the characterization of the hybrid system electronic features. In this work, we investigate a eumelanin/Si interface, where Si plays the role of inorganic layer. By means of ab initio calculations, we study the feasibility of the experimental formation process of eumelanin protomolecular structures in methanol ambient, evaluating the corresponding formation energy. Then, we explore the adhesion properties of eumelanin molecules on a silicon surface and extract the electronic structure of the resulting system. The corresponding band alignment is then used to address the overall photoconversion efficiency. Adopting the scheme of chemical disorder, which has been proved to successfully capture the variety of eumelanin protomolecules, we show that (1) the formation process of eumelanin protomolecules from the constituting monomers is generally hindered in a solvent environment with respect to vacuum and (2) key factors in improving the adhesion properties and band lineup of the molecules on an inorganic interface are the molecular electronic state and the planarity of their structures. Protomolecular models with a large number of nonterminated oxygen atoms and endowed with an intrinsically planar character tend to bind more strongly to the surface. In addition, they are more likely to produce a favorable band alignment for photoconversion applications., We acknowledge the Regione Sardegna basic research Project No. CRP78744 “Energy Applications with Porous Silicon (ENAPSi)”. E.C. acknowledges support by MINECO (Spain) through Grant FIS2015-64886-C5-4-P and the Severo Ochoa Centers of Excellence Program (Grant SEV-2015-0496) as well as by Generalitat de Catalunya (2014SGR301).

We theoretically study the electrical, thermal and thermoelectric transport properties of graphene nanoribbons under torsional deformations. The modelling follows a nonequilibrium Green's function approach in the ballistic transport regime, describing the electrical and phononic properties through \textit{ab-initio} density functional theory and empirical interatomic potentials, respectively. We consider two different types of deformations, a continuous twist of a given angle applied to the nanoribbon, and two consecutive twists applied in opposite angular directions. The numerical results are carefully analysed in terms of spatially-resolved electron eigenchannels, polarization-dependent phonon transmission and thermoelectric figure-of-merit.

In this paper we present an efficient model for current calculation through silicon nanocrystals. The model uses self consistent field approach to calculate the evolution of transmission spectra and Landauer formalism for current calculations. We implemented the split in spectra for different spin so that the model works in case of coulomb blockade. A few simulations were performed using a physical simulator to extract parameters to be inserted in model. The current voltage characteristics were calculated from the model for structures with different geometry and coupling strength between the lattice and contacts. The results from the model show good accordance with those from physical simulator and are obtained with more than two orders of magnitude speed up.

Nanowire field effect transistors (FETs) with multiple independent gates around a silicon channel feature ultimate gate control, and are regarded as promising candidates for next-generation transistors. Being inherently more complex than the conventional gate-all-around nanowire FETs, they require longer simulation time, especially with numerical simulations. We present a new model, enabling the efficient computation of voltages and current in modular semiconductor structures with an arbitrary number of independent gate regions. Its validity extends on gate-all-around MOSFETs, FinFETs, and gateless channels. It exploits existing models for conventional devices and builds results on top of these. Being completely general, the method is independent from the models used to describe each region, a charge-based model in our case. Applied to a multiindependent-gate nanowire FET structure, extensive comparison of the proposed method with results from physics-based TCAD Atlas software and with numerical exact results show very good agreement with relative errors of less than 1.8% for potentials and less than 4% for currents, under a broad variations of physical parameters as well as biasing conditions. Interpreted language implementation shows a performance advantage in excess of one order of magnitude with respect to standard optimized numerical methods, still providing excellent accuracy, and making it suitable for implementation in circuit simulators.

Semiconducting nanowires with transverse dimensions of less than 10nm are considered, among all, as good candidates for gas sensing applications. Interaction with molecules and surface materials modifies the transport properties of the wire, largely dominated by quantum effects. Here we propose a systematic analysis of the transport properties of a silicon nanowire interacting with a surface material with different geometrical and electrical properties. We demonstrate the sensitivity of the transmission spectrum and current on the external layer thickness and permittivity, surface charge density and surface coverage.

Porous Si/eumelanin hybrids are a novel class of organic-inorganic hybrid materials that hold considerable promise for photovoltaic applications. Current progress toward device setup is, however, hindered by photocurrent stability issues, which require a detailed understanding of the mechanisms underlying the buildup and consolidation of the eumelanin-silicon interface. Herein we report an integrated experimental and computational study aimed at probing interface stability via surface modification and eumelanin manipulation, and at modeling the organic-inorganic interface via formation of a 5,6-dihydroxyindole (DHI) tetramer and its adhesion to silicon. The results indicated that mild silicon oxidation increases photocurrent stability via enhancement of the DHI-surface interaction, and that higher oxidation states in DHI oligomers create more favorable conditions for the efficient adhesion of growing eumelanin.

Molecular QCA are considered among the most promising beyond CMOS devices. Frequency as well as self-assembly characteristics are the features that make them most attractive. Several challenges restrain them for being exploited from a practical point of view in the near future, not only for the difficulties at the technological level, but for the inappropriateness of the tools used when studying and predicting their behavior.

Porous Silicon Nanowires (PS-NWs) represent very promising electronic devices with a wide range of applications, all taking advantage of the irregular microscopic structure of PS. The strong variability of the electrical properties of the material with technological process makes computer simulation of PS-nanowires a cumbersome task. Here we present a simple model of PS-NWs which can be implemented for simulations in physics-based software TCAD Atlas thus giving a contribution to the investigation of the effects of the peculiar structure on the material resistivity. Extensive simulations have been performed on PS-Nws with microscopic characteristics deduced from our experimental fabricated devices. We investigated the dependence of current from applied voltage and channel doping also in relation with the electrical field inside the device and with the carriers' mobility. Finally we suggest an electrical model for PS-NWs easily implemented in commercial circuit simulators (Eldo in this case). It will allow to exploit the actual simulation tools also for the analysis and design of circuits where PS-based devices are present