A Backscattering Model Incorporating the Effective Carrier Temperature in Nano MOSFET

In this work we propose a channel backscattering model in which increased carrier temperature at the top of the potential energy barrier in the channel is taken into account. This model represents an extension of a previous model by the same authors which highlighted the importance of considering the partially ballistic transport between the source contact and the top of the potential energy barrier in the channel. The increase of carrier temperature is precisely due to energy dissipation between the source contact and the top of the barrier caused by the high saturation current. To support our discussion, accurate 2D full band Monte Carlo device simulations with quantum correction have been performed in double gate nMOSFETs for different geometries (gate length down to 10 nm), biases and lattice temperatures. Including the effective carrier temperature is especially important to properly treat the high inversion regime, where previous backscattering models usually fail

Study of Warm Electron Injection in Double Gate SONOS by Full Band Monte Carlo Simulation

In this paper we investigate warm electron injection in a double gate SONOS memory by means of 2D full-band Monte Carlo simulations of the Boltzmann Transport Equation (BTE). Electrons are accelerated in the channel by a drain-to-source voltage VDS smaller than 3 V, so that programming occurs via electrons tunneling through a potential barrier whose height has been effectively reduced by the accumulated kinetic energy. Particle energy distribution at the semiconductor/oxide interface is studied for different bias conditions and different positions along the channel. The gate current is calculated with a continuum-based post-processing method as a function of the particle distribution obtained from Monte Carlo. Simulation results show that the gate current increases by several orders of magnitude with increasing drain bias and warm electron injection can be an interesting option for programming when short channel effects prohibit the application of larger drain bias

Transient Analysis of Warm Electron Injection Programming of Double Gate SONOS Memories by means of Full Band Monte Carlo Simulation

In this paper we investigate "Warm Electron Injection" as a mechanism for NOR programming of double-gate SONOS memories through 2D full band Monte Carlo simulations. Warm electron injection is characterized by an applied VDS smaller than 3.15 V, so that electrons cannot easily accumulate a kinetic energy larger than the height of the Si/SiO2 barrier. We perform a time-dependent simulation of the program operation where the local gate current density is computed with a continuum-based method and is adiabatically separated from the 2D full Monte Carlo simulation used for obtaining the electron distribution in the phase space. In this way we are able to compute the time evolution of the charge stored in the nitride and of the threshold voltages corresponding to forward and reverse bias. We show that warm electron injection is a viable option for NOR programming in order to reduce power supply, preserve reliability and CMOS logic level compatibility. In addition, it provides a well localized charge, offering interesting perspectives for multi-level and dual bit operation, even in devices with negligible short channel effects

Liver resections: complications and survival outcome

none1noToday, liver resection represents one of the most effective therapies in the treatment of defined liver diseases, particularly for hepatocellular carcinomas, liver metastases and tumors originating from the bile ducts. There have been a number of improvements in the technique but the use of kellyclasia associated with meticulous control of hemostasis and biliostasis appears to be more effective and efficient. The procedure is still burdened with some postoperative complications, the more characteristic of which are liver insufficiency, biliary leakage and ascites. Several neoplastic diseases, both primitive and secondary, can benefit from this therapy with substantial improvement of long-term survival, and a notable change in the natural history of the disease. For these situations, a consultation should always be performed by a surgeon experienced in hepatic surgery.mixedGrazi GLGrazi G

NANOTCAD2D: Two-dimensional code for the simulation of nanoelectronic devices and structures

In this paper we present NANOTCAD2D, a code for the simulation of the electrical properties of semiconductor-based nanoelectronic devices and structures in two-dimensional domains. Such code is based on the solution of the Poisson/Schr\"odinger equation with density functional theory and of the continuity equation of the ballistic current. NANOTCAD2D can be applied to structures fabricated on III-IV, strained-silicon and silicon-germanium heterostructures, CMOS structures, and can easily be extended to new materials. In particular, in the case of SiGe heterostructures, it computes the effects of strain on the energy band profiles. The effects of interface states at the air/semiconductor interfaces, particularly significant in the case of devices obtained by selective etching, are also properly taken into account.Comment: 23 pages, 11 figure

Metal-Semiconductor Transition in Armchair Carbon Nanotubes by Symmetry Breaking

The electronic band structure of armchair carbon nanotubes may be considerably modified by potentials with angular dependence. Different angular modes V_q ~ cos(q*theta) have been studied within a tight-binding scheme. Using symmetry arguments, we demonstrate a bandgap opening in these metallic nanotubes when certain selection rules are satisfied for both potential and nanotube structure. We estimate the bandgap opening as a function of both the external potential strength and the nanotube radius and suggest an effective mechanism of metal-semiconductor transition by combination of different forms of perturbations.Comment: 3 pages, 3 figures, published on AP