Two-dimensional confinement effects in gate-all-around (GAA) MOSFETS

Two-dimensional electron confinement effects have been modeled and experimentally observed in silicon-on-insulator (SOI) gate-all-around (GAA) MOSFETs. Solving the Poisson and Schrodinger equations in a self-consistent manner provides the electron wave functions and the energy levels within the device channel. The variation of these energy levels, as well as the electron concentration profile, have been computed as a function of gate voltage. Transconductance fluctuations are observed as new energy levels become populated. (C) 1998 Elsevier Science Ltd. All rights reserved

Fabrication of twin nano silicon wires based on arsenic dopant effect

This paper reports a simple fabrication process of Si "twin nano wires" based on As dopant effect which gives rise to a significant increase of the oxidation rate at the peak concentration of As. The processing procedures consist of As doping, deposition of silicon nitride layer, electron beam lithography, reactive ion etching, wet oxide and deposition of polysilicon. The resulting Si "twin nano wires': have a small top wire with a dimension of 10 nm and a triangular channel wire with a height of 250 nm. A possible application of the "twin nano wires" to a future single-electron memory device on silicon on insulator (SOI) wafer is also discussed

Evidence of 2-dimensional Carrier Confinement in Thin N-channel Soi Gate-all-around (gaa) Devices

The effect of two-dimensional electron confinement is observed in thin-film, gate-all-around SOI transistors operated at low temperature. Physical 21) confinement in a thin silicon film using the silicon/gate oxide potential barrier (in contrast to heterojunction or electrostatic confinement) is shown for the first time. In these devices volume inversion gives rise to a 2DEG, and the population of the energy subbands can be controlled by the gate voltage. The position of transconductance peaks and valleys, corresponding to the population of different subbands as the gate voltage is increased, is in good agreement with theoretical predictions

A silicon-on-insulator quantum wire

Thin, narrow silicon-on-insulator n-channel MOSFETs have been fabricated. The drain current characteristics, when measured as a function of gate voltage at low temperature, exhibit a series of oscillations, which is characteristic of current transport in one-dimensional systems (quantum wires). Theoretical calculation of the current oscillations in the device show reasonable agreement with the experimental characteristics

Formation of Pt-based silicide contacts : kinetics, stochiometry and current drive capabilities

A detailed analysis of the formation of Pt2Si and PtSi silicides is proposed, based on x-rayphotoelectron spectroscopy ~XPS!, transmission electron microscopy ~TEM!, and electricalcharacterizations. Published kinetics of the Pt2Si and PtSi transformations under ultrahigh vacuumcondition are consolidated on the basis of XPS measurements performed during an in situ annealingat a constant heating rate. At room temperature, an incomplete PtxSi reaction is clearly identified byXPS depth profiling. Using rapid thermal annealing at 300, 400, and 500 °C, the sequentialPt–Pt2Si–PtSi reaction chain is found to be completed within 2 min. Outdiffusion of silicon to thetop surface is shown to be responsible for the formation of a thin SiO2 capping layer at 500 °C.Pileup of oxygen occurring at the Pt2Si/Pt reaction front is clearly identified as an inhibiting factorof the silicidation mechanism. Another incomplete reaction scheme limited to the unique formationof Pt2Si is exemplified in the case of ultra thin silicon-on-insulator films. Finally, current drivemeasurements on PtSi Schottky contacts have allowed us to identify 300 °C as the optimumannealing temperature while TEM cross sections demonstrate the formation of a smooth andcontinuous PtSi/Si interface at 300 °C

Two-dimensional self-consistent simulation of a triangular P-channel SOI nano-flash memory device

This paper presents the simulation of an SOI nano-flash memory device. The device is composed of a triangular quantum wire channel P-MOSFET with a self-aligned nano-floating gate embedded in the gate oxide. The simulation is carried out by combining TSUPREM-4 [1] and a two-dimensional (2-D) self-consistent solution of the Poisson and Schrodinger equations. The fabrication process as well as quantum physics are taken into account. Hole distribution in the inversion layer of the triangular channel section. is calculated in terms of wave functions and energy subbands. The threshold voltage shift between the programming and erasing of the device is investigated. In this paper, we show that the channel shape plays a crucial role in the programming voltage and the threshold voltage shift. Based on the fact that the holes are confined mainly at the top of the triangular channel section, we explain why our triangular channel device can be operated at relatively low programming voltage despite of a thick gate oxide and tunnel oxide. The threshold voltage shift in the triangular channel device is compared with that in a rectangular channel device. The result shows that the triangular channel device exhibits the larger threshold voltage shift

Influence of Device Geometry on SOI Single-Hole Transistor Characteristics

SOI single-hole transistors have been fabricated by intentionally converting a quantum wire to an island connected to source and drain by two narrow constrictions. Two devices with different constriction lengths were investigated. It is found that slight differences in constriction lengths can lead to dramatic differences in device characteristics. For the device with short constrictions, periodic Coulomb oscillations are obtained and persist at temperatures in excess of 100 K. The physical origin of the tunnel barriers of the device has been analyzed experimentally and investigated theoretically based on the self-consistent numerical results of the Schrödinger and Poisson equations. The result indicates that lower ground-state energy for holes in the narrow constrictions serves as a potential barrier responsible for the periodic Coulomb oscillations. For the device with longer constrictions, aperiodic drain current oscillations are observed. The analysis of the experimental results shows that the quantum wire connecting source and drain is converted into at least three islands, probably due to the pattern-dependent oxidation effect. Consequently, the charging energy combined with the quantum confinement energy for the smallest island gives rise to aperiodic drain current oscillations

Contribution de l imagerie par résonance magnétique (IRM) dans le syndrome de dysfonction apicale transitoire ou Tako-Tsubo

Le syndrome de dysfonction apicale transitoire ou Tako-Tsubo est une entité rare individualisée récemment qui associe modifications électrocardiographiques, douleurs thoraciques, élévation des enzymes cardiaques, akinésie apicale ventriculaire transitoire et coronaires angiographiquement normales. Elle survient quasi exclusivement chez la femme ménopausée et est souvent déclenchée par un stress. Nous avons étudié ses caractéristiques en IRM cardiaque chez 10 patientes à la phase précoce (n=6) et à distance (n=8). Nos résultats, concordants avec les quelques données disponibles dans la littérature, montrent qu il n y a pas de rehaussement tardif après injection de gadolinium, éliminant ainsi une séquelle de nécrose myocardique. L IRM cardiaque permet également d éliminer deux des principaux diagnostics différentiels, l infarctus à coronaires saines et la myocardite. Nous discutons enfin des implications potentielles de ces résultats.NANTES-BU Médecine pharmacie (441092101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF