> Research > CMNE > Modeling and Simulation
Contact: Marco Pala
Support: Agence National de la Recherche, « NOODLES » Project, « MOSINAS » Project, « QUASANOVA » Project, « QUANTAMONDE » Project.
EU commission, « COMPOSE3 » Project, « SQUWIRE » Project, « NANOSIL » NoE, « SINANO » NoE.
Relevant publications:
· S. Brocard, M.G. Pala and D. Esseni, Large OnCurrent Enhancement in HeteroJunction TunnelFETs via Molar Fraction Grading, IEEEElectron Device Letters 35, 184 (2014).
· M.G. Pala and D. Esseni, Interface Traps in InAs Nanowire TunnelFETs and MOSFETs—Part I: Model Description and Single Trap Analysis in TunnelFETs, IEEE Trans. Electron Devices 60, 2795 (2013).
· F. Conzatti, M.G. Pala, D. Esseni, Surface Roughness Induced Variability in Nanowire InAs TunnelFETs, IEEEElectron Device Letters 33, 806 (2012).
· F. Conzatti, M.G. Pala, D. Esseni, E. Bano, and L. Selmi, Straininduced performance improvements in InAs nanowire tunnel Fets, IEEE Trans. Electron Devices 59, 2085 (2012).
· A. Cresti, M.G. Pala, S. Poli, M. Mouis, and G. Ghibaudo, A Comparative Study of SurfaceRoughnessInduced Variability in Silicon Nanowire and DoubleGate FETs, IEEE Trans. Electron Devices 58, 2274 (2011).
· S. Poli and M.G. Pala, ChannelLength Dependence of LowField Mobility in SiliconNanowire FETs, IEEE Electron Device Letters 30, 1515 (2009).
· S. Poli, M.G. Pala, T. Poiroux, S. Deleonibus, and G. Baccarani, Size dependence of surfaceroughnesslimited mobility in Siliconnanowire FETs, IEEE Trans. Electron Devices 55, 2968 (2008).
· Th. Schäpers, V. A. Guzenko, M.G. Pala, et al., Suppression of weak antilocalization in GaInAs/InP narrow quantum wires, Physical Review B 74, 081301 (2006).

The observation of high quality integer quantum Hall effect in graphene at room temperature has galvanized the scientific community for the possible metrological applications (new standard of resistance) as well as for more fundamental physics aspects (as the degeneracy lifting of the graphenespecific zero Landau level). We investigate the interplay between magnetic field and disorder in determining the electronic transport properties of graphene ribbons. The combination of atomistic tightbinding description and full quantum Green’s function approach allows us to consider different types of experimentally relevant disorder sources as shortrange potential (adsorbates, vacancies…), longrange disorder (charged impurities) and geometrical distortion (scrolls, ripples…). Depending on the disorder nature, interesting effects can be predicted, as for example the quenching of the integer quantum Hall effect in ribbons with scrolled edges or in narrow ribbons with moderate disorder. 
Contact: Alessandro Cresti
Recent publications:
· A. Cresti, M.M. Fogler, F. Guinea, A.H. Castro Neto and S. Roche, Quenching of the Quantum Hall Effect in Graphene with Scrolled Edges, Physical Review Letters 108, 166602 (2012).
· K.L. Chiu, M.R. Connolly, A. Cresti, C. Chua, S.J. Chorley, F. Sfigakis, S. Milana, A.C. Ferrari, J.P. Griffiths, G.A.C. Jones and C.G. Smith, Singleparticle probing of edgestate formation in a graphene nanoribbon, Physical Review B 85, 205452 (2012).
· R. Ribeiro, J.M. Poumirol, A. Cresti, W. Escoffier, M. Goiran, J.M. Broto, S. Roche and B. Raquet, Unveiling the Magnetic Structure of Graphene Nanoribbons, Physical Review Letters 107, 86601 (2011).
Analytical modeling of short channel effects showing the significant role of the source and drain on the value of DIBI and subthreshold slope (T. Dutta et al., ULIS Conference 2013 
We are developing analytical models in order to capture as many effects as possible (e.g. quasi ballistic transport, sourcedrain leakage, accurate short channel effects etc.), that are playing a key role in nano MOSFETs. These models are extensively compared to advanced simulations codes (NEGF, TCAD, MC with our collaboration with DIEGM/Udine). In particular, many studies have been focused on the evaluation of Ge and IIIV channel devices, which are presently a realistic option for the end of the roadmap. A strong collaboration with the Advanced Device group in ST Microelectrics allows us to transfert our model in the MaSTar plateform and hence reach a larger audience. 
Contact: Quentin Rafhay
Support: STREP Compose3  ANR MOSINAS  ANR Noddle
See for instance: Quentin Rafhay, Raphaël Clerc, Gérard Ghibaudo, Georges Pananakakis, Impact of sourcetodrain tunnelling on the scalability of arbitrary oriented alternative channel material nMOSFETs, SolidState Electronics 52, 14741481 (2008).
Recent publications:
• B. Sklenard, P. Batude, Q. Rafhay, et al., Influence of device architecture on junction leakage in lowtemperature process FDSOI MOSFETs, SolidState Electronics 88, 9 (2013).
• T. Dutta, Q. Rafhay, et al., Impact of quantum effects on the short channel effects of IIIV nMOSFETs in weak and strong inversion regimes, SolidState Electronics 88, 43 (2013).
• I. Ben Akkez, A. Cros, C. FenouilletBeranger, F. Boeuf, Q. Rafhay, F. Balestra, G. Ghibaudo, New parameter extraction method based on split C–V measurements in FDSOI MOSFETs, SolidState Electronics 84, 142 (2012).
• A. Zaka, P. Palestri, Q. Rafhay, R. Clerc, M. Iellina, D. Rideau, C. Tavernier, G. Pananakakis, H. Jaouen, L. Selmi, An Efficient Nonlocal Hot Electron Model Accounting for ElectronElectron Scattering, IEEE Trans. Electron Devices 59, 983 (2012).
• A. Zaka, J. Singer, E. Dornel, D. Garetto, D. Rideau, Q. Rafhay, R. Clerc, J.P. Manceau, N. Degors, C. Boccaccio, C. Tavernier, H. Jaouen, Characterization and 3D TCAD simulation of NORtype flash nonvolatile memories with emphasis on corner effects, SolidState Electronics 63, 158 (2012).
• A. Zaka, Q. Rafhay, M. Iellina, P. Palestri, R. Clerc, D. Rideau, D. Garetto, E. Dornel, J. Singer, C. Tavernier, G. Pananakakis, H. Jaouen, On the Accuracy of Current TCAD Hot Carrier Injection Models in Nanoscale Devices, SolidState Electronics 54, 1669 (2010).
• M.F. Beug, Q. Rafhay, M.J. van Duuren, R. Duane, Investigation of BackBias Capacitance Coupling Coefficient Measurement Methodology for FloatingGate Nonvolatile Memory Cells, IEEE Trans. Electron Devices 57, 1253 (2010).
Calculation of the hole conduction mass reduction
due to a longitudinal compressive stress along the
[110] direction. In contrast, the transverse mass
almost keeps its unstrained value.
An analytical model of electron and hole mobility in strained silicon is being developed in order to describe low field transport along any channel orientation with an arbitrary stress configuration (arbitrary stress tensor). The model, which runs in a few seconds on a standard PC, is based on an exact solution of the 6x6 k.p Hamiltonian coupled with a KuboGreenwood approach for mobility calculation. It can be used to support the interpretation of experimental results in terms of strain induced mobility variations or to find channel orientations and stress configurations that optimize carrier transport.
Contact: Alessandro Cresti
Recent publications:
• A. Cresti, Scaling properties of diffusive electronic transport in graphene nanoribbons functionalized with methylgroups, J. Comput. Electron. 12, 94 (2013)
• P. Marconcini, A. Cresti, F. Triozon, G. Fiori, B. Biel, Y.M. Niquet, M. Macucci and S. Roche, Atomistic borondoped Graphene FieldEffect Transistors: A Route toward Unipolar Characteristics, ACS Nano 6, 7942 (2012)
• S. Roche, B. Biel, A. Cresti and F. Triozon, Chemically enriched graphenebased switching devices: A novel principle driven by impurityinduced quasibond states and quantum coherence, Physica E 44, 960 (2012).
• A. Cresti, A. LopezBezanilla, P. Ordejón and S. Roche, Oxygen surface functionalization of graphene nanoribbons for transport gap engineering, ACS Nano 5, 9271 (2011).
Contact: Marco Pala
Recent publications:
• A. Braggio, M.G. Pala, M. Governale, J. König, Superconducting proximity effect in interacting quantum dots revealed by shot noise, SolidState Communications 151, 155, (2011).
• D. J. Eldridge, M.G. Pala, M. Governale, J. König, Superconducting proximity effect in interacting doubledot systems, Physical Review B 82, 184507 (2010).
• D. Futterer, M. Governale, M.G. Pala, and J. König, Nonlocal Andreev transport through an interacting quantum dot, Physical Review B 79, 054505 (2009).
• M. Governale, M.G. Pala, and J. König, Realtime diagrammatic approach to transport through interacting quantum dots with normal and superconducting leads, Physical Review B 78, 069902 (2008).
• M.G. Pala, M. Governale, and J. König, NonEquilibrium Josephson and Andreev Current through Interacting Quantum Dots, New Journal of Physics 9, 278 (2007).

The increasing need for autonomous applications demands the development of efficient energy harvesting techniques, mainly based on thermoelectricity, piezoelectricity or photovoltaic effect. In the last decade, material nanostructuration has allowed a significant increase of the thermoelectric ZT factor of merit thanks to the combined effect of thermal conductivity decrease and moderate impact on the electron conductivity. In our group, we focus on semiconductor nanowires, which have been experimentally seen to be very promising in this respect. We describe the interatomic coupling by a valence force model, which is able to account for experimentally relevant sources of disorder such as roughness, and estimate the thermal conductivity by the Green’s function approach. The combination with electronic transport simulation, for the calculation of conductivity, Seebeck coefficient and electronic thermal conductivity, allows us to estimate the ZT factor and to explore new possible roots for its engineering. lead. 
Contact: Alessandro Cresti , Marco Pala
See for instance: G. Ardila, A. KaminskiCachopo, M. Pala, A. Cresti, L. Montes, R. Hinchet, J. Michallon, M. Daanoune, M. Mouis, Towards selfpowered systems: using nanostructures to harvest ambient energy, 2nd UkrainianFrench Seminar, April 811 2013, Kiev, Ukraine
Date of update November 4, 2019