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Search Results: 1 - 10 of 368285 matches for " G. C. Tettamanzi "
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Charge Pumping Through a Single Donor Atom
G. C. Tettamanzi,R. Wacquez,S. Rogge
Physics , 2014, DOI: 10.1088/1367-2630/16/6/063036
Abstract: Presented in this paper is a proof-of-concept for a new approach to single electron pumping based on a Single Atom Transistor (SAT). By charge pumping electrons through an isolated dopant atom in silicon, precise currents of up to 160 pA at 1 GHz are generated, even if operating at 4.2 K, with no magnetic field applied, and only when one barrier is addressed by sinusoidal voltage cycles.
Superconducting transition in Nb nanowires fabricated using focused ion beam
G. C. Tettamanzi,C. I. Pakes,A. Potenza,S. Rubanov,C. H. Marrows,S. Prawer
Physics , 2010, DOI: 10.1088/0957-4484/20/46/465302
Abstract: Making use of focused Ga-ion beam (FIB) fabrication technology, the evolution with device dimension of the low-temperature electrical properties of Nb nanowires has been examined in a regime where crossover from Josephson-like to insulating behaviour is evident. Resistance-temperature data for devices with a physical width of order 100 nm demonstrate suppression of superconductivity, leading to dissipative behaviour that is shown to be consistent with the activation of phase-slip below Tc. This study suggests that by exploiting the Ga-impurity poisoning introduced by the FIB into the periphery of the nanowire, a central superconducting phase-slip nanowire with sub-10 nm dimensions may be engineered within the core of the nanowire.
Coherent transport through a double donor system in silicon
J. Verduijn,G. C. Tettamanzi,G. P. Lansbergen,N. Collaert,S. Biesemans,S. Rogge
Physics , 2009, DOI: 10.1063/1.3318271
Abstract: Quantum coherence is of crucial importance for the applicability of donor based quantum computing. In this Letter we describe the observation of the interference of conduction paths induced by two donors in a nano-MOSFET resulting in a Fano resonance. This demonstrates the coherent exchange of electrons between two donors. In addition, the phase difference between the two conduction paths can be tuned by means of a magnetic field, in full analogy to the Aharonov-Bohm effect.
Heterointerface effects on the charging energy of shallow D- ground state in silicon: the role of dielectric mismatch
M. J. Calderon,J. Verduijn,G. P. Lansbergen,G. C. Tettamanzi,S. Rogge,Belita Koiller
Physics , 2010, DOI: 10.1103/PhysRevB.82.075317
Abstract: Donor states in Si nanodevices can be strongly modified by nearby insulating barriers and metallic gates. We report here experimental results indicating a strong reduction in the charging energy of isolated As dopants in Si FinFETs relative to the bulk value. By studying the problem of two electrons bound to a shallow donor within the effective mass approach, we find that the measured small charging energy may be due to a combined effect of the insulator screening and the proximity of metallic gates.
New tools for the direct characterisation of FinFETs
G. C. Tettamanzi,A. Paul,S. Lee,G. Klimeck,S. Rogge
Physics , 2011,
Abstract: This paper discusses how classical transport theories such as the thermionic emission, can be used as a powerful tool for the study and the understanding of the most complex mechanisms of transport in Fin Field Effect Transistors (FinFETs). By means of simple current and differential conductance measurements, taken at different temperatures and different gate voltages ($V_G$'s), it is possible to extrapolate the evolution of important parameters such as the spatial region of transport and the height of thermionic barrier at the centre of the channel. Furthermore, if the measurements are used in conjunction with simulated data, it becomes possible to also extract the interface trap density of these objects. These are important results, also because these parameters are extracted directly on state-of-the-art devices and not in specially-designed test structures. The possible characterisation of the different regimes of transport that can arise in these ultra-scaled devices having a doped or an undoped channel are also discussed. Examples of these regimes are, full body inversion and weak body inversion. Specific cases demonstrating the strength of the thermionic tool are discussed in sections \ref{sec:II}, \ref{sec:III} and \ref{sec:IV}. This text has been designed as a comprehensive overview of 4 related publications (see Ref. [2-5]) and has been submitted as a book chapter in Ref. [6]).
Tunable Kondo effect in a single donor atom
G. P. Lansbergen,G. C. Tettamanzi,J. Verduijn,N. Collaert,S. Biesemans,M. Blaauboer,S. Rogge
Physics , 2009, DOI: 10.1021/nl9031132
Abstract: The Kondo effect has been observed in a single gate-tunable atom. The measurement device consists of a single As dopant incorporated in a Silicon nanostructure. The atomic orbitals of the dopant are tunable by the gate electric field. When they are tuned such that the ground state of the atomic system becomes a (nearly) degenerate superposition of two of the Silicon valleys, an exotic and hitherto unobserved valley Kondo effect appears. Together with the regular spin Kondo, the tunable valley Kondo effect allows for reversible electrical control over the symmetry of the Kondo ground state from an SU(2)- to an SU(4) -configuration.
Reply on the comment on the paper "Superconducting transition in Nb nanowires fabricated using focused ion beam"
G. C. Tettamanzi,A. Potenza,S. Rubanov,C. H. Marrows,S. Prawer
Physics , 2010, DOI: 10.1088/0957-4484/21/16/168002
Abstract: In this communication we present our response to the recent comment of A. Engel regarding our paper on FIB- fabricated Nb nanowires (see Vol. 20 (2009) Pag. 465302). After further analysis and additional experimental evidence, we conclude that our interpretation of the experimental results in light of QPS theory is still valid when compared with the alternative proximity-based model as proposed by A. Engel.
A New Rearranged Non-Aromatic Salpichrolide from Salpichroa Origanifolia
M. C. Tettamanzi,A. S. Veleiro,J. R. De La Fuente,G. Burton
Molecules , 2000, DOI: 10.3390/50300449
Abstract: From the aerial parts of Salpichroa origanifolia a new withanolide in which the C-13 angular methyl has migrated to C-17, was isolated and characterized by spectroscopic methods.
Dopant metrology in advanced FinFETs
G. P. Lansbergen,R. Rahman,G. C. Tettamanzi,J. Verduijn,L. C. L. Hollenberg,G. Klimeck,S. Rogge
Physics , 2011,
Abstract: Ultra-scaled FinFET transistors bear unique fingerprint-like device-to-device differences attributed to random single impurities. This paper describes how, through correlation of experimental data with multimillion atom tight-binding simulations using the NEMO 3-D code, it is possible to identify the impurity's chemical species and determine their concentration, local electric field and depth below the Si/SiO$_{\mathrm{2}}$ interface. The ability to model the excited states rather than just the ground state is the critical component of the analysis and allows the demonstration of a new approach to atomistic impurity metrology.
Magnetic Field Probing of an SU(4) Kondo Resonance in a Single Atom Transistor
G. C. Tettamanzi,J. Verduijn,G. P. Lansbergen,M. Blaauboer,M. J. Calderón,R. Aguado,S. Rogge
Physics , 2011, DOI: 10.1103/PhysRevLett.108.046803
Abstract: Semiconductor nano-devices have been scaled to the level that transport can be dominated by a single dopant atom. In the strong coupling case a Kondo effect is observed when one electron is bound to the atom. Here, we report on the spin as well as orbital Kondo ground state. We experimentally as well than theoretically show how we can tune a symmetry transition from a SU(4) ground state, a many body state that forms a spin as well as orbital singlet by virtual exchange with the leads, to a pure SU(2) orbital ground state, as a function of magnetic field. The small size and the s-like orbital symmetry of the ground state of the dopant, make it a model system in which the magnetic field only couples to the spin degree of freedom and allows for observation of this SU(4) to SU(2) transition.
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