Toufik Bentrcia

Continuous analytic I?V model for GS DG MOSFETs including hot-carrier degradation effects

We have studied the influence of hot-carrier degradation effects on the drain current of a gate-stack double-gate (GS DG) MOSFET device. Our analysis is carried out by using an accurate continuous current?voltage (I?V) model, derived based on both Poissons and continuity equations without the need of charge-sheet approximation. The developed model offers the possibility to describe the entire range of different regions (subthreshold, linear and saturation) through a unique continuous expression. Therefore, the proposed approach can bring considerable enhancement at the level of multi-gate compact modeling including hot-carrier degradation effects.

Drain current model for undoped Gate Stack Double Gate (GSDG) MOSFETs including the hot-carrier degradation effects

In this paper, analytical models of drain current and small signal parameters for undoped symmetric Gate Stack Double Gate (GSDG) MOSFETs including the interfacial hot-carrier degradation effects are presented. The models are used to study the device behavior with the interfacial traps densities. The proposed model has been implemented in the SPICE circuit simulator and the capabilities of the model have been explored by circuit simulation example. The developed approaches are verified and validated by the good agreement found with the 2D numerical simulations for wide range of device parameters and bias conditions. GSDG MOSFET design and the accurate proposed model can alleviate the critical problem and further improve the immunity of hot-carrier effects of DG MOSFET-based circuits after hot-carrier damage.

An analytical two dimensional subthreshold behavior model to study the nanoscale GCGS DG Si MOSFET including interfacial trap effects

Abstract In order to pursue the miniaturization process as predicted by Moor’s law and go beyond actual reached lengths, more condensed efforts should be focused not only on looking for higher mobility materials but also on improving existing topologies of nanocircuit digital devices, which are the corner stone of currently used information storage supports. Therefore, the aim of this paper is to provide a quantitative analysis about the efficiency of our proposed structure Graded Channel Gate Stack Double Gate on Si MOSFET (GCGS DG Si MOSFET) in remedying the short channel and hot carrier degradation effects. The analysis is carried out by using an analytical 2-D subthreshold behavior model consolidated with numerical simulations (SILVACO), where the proposed structure shows an improvement and immunity against the hot carriers in terms of threshold voltage and swing factor. Moreover, the developed analytical models including the device immunity effect are compared with those of the conventional DG MOSFET, where a significant enhanced performance is predicted for the case of our proposed design. Consequently, it can be reasonably claimed that the (GCGS) DG Si MOSFET structure can alleviate the short channel and hot carrier degradation effects and further improves the device reliability for the nanoelectronic digital applications.

Numerical Investigation of the SiGe/Si Heterostructure Including Interfacial Defects for Photovoltaic Applications

To improve the electrical performance and reduce the fabrication cost of the solar cell, thin-film solar-cell concepts are widely explored. In this context, many studies have been carried out to study the impact of the thin thickness of the material on the solar cell behavior. Recently, the Si1-xGex/Si heterostructure is considered as attractive alternative for photovoltaic applications due to their band structures, which allow getting an additional gain in the device efficiency. However, the growth of this material is not totally controlled, and the presence of interfacial defects is more than estimated after a growth run of this material. Therefore, new experimental and numerical investigations which capture the Si1-xGex/Si heterostructure behavior should be developed in order to build a complete Si1-xGex/Si-based solar cell model for photovoltaic applications. In this paper, we aim at highlighting the immunity of the Si1-xGex/Si heterostructure against the defects degradation effect at nanoscale level (thin films). The effect of interface defect on the heterostructure has been carried out by extensive simulation using Atlas 3-D simulator, including the device dimension and the Ge Mole fraction effects.

An accurate two dimensional threshold voltage model for nanoscale GCGS DG MOSFET including traps effects

There is no doubt that nanoelectronics based applications are the workhorse of the next industrial revolution, such importance has induced an accelerated research towards novel models governing behavior aspects of nanoscale components. Despite the proved advantages of GCGS DG MOSFETs topology, challenges continue to occur particularly concerning from a part models accuracy and from another part reliability of new invented devices. This paper explores the surface -potential -based approach to derive an analytical threshold voltage model for nanoscale GCGS DG MOSFET at low drain-source voltage. Our obtained results showed considerable improvement compared to conventional DG MOSFETs. Followed steps presented herein may provide guidance and orientation needed for meaningful reliability measurements related to immunity of nanoscale DG MOSFETs against the hot-carrier degradation effects.

Equivalent circuit modeling of SiGe/Si solar cell including interfacial defect effects

In this paper the numerical investigation of the Sil-xGex/Si heterostructure solar cell is proposed. The proposed investigation is based on the study of the immunity of the Sil-xGex/Si heterostructure against the defects degradation effect at nanoscale level (thin films). The numerical analysis takes into consideration the impact of the interface defects on the solar cell behavior. In addition, a new equivalent electrical circuit of the solar cell before and after the setting up of defect degradation effects is developed in this study. The developed equivalent circuit can be implemented into solar cell simulator like: SPICE and PCID, in order to study the impact of the interface defects on the photovoltaic systems. The proposed investigation is intended to be an aid to solar cell designers.

Numerical investigation of nanoscale SiGe DG MOSFET with graded doping channel for improving reliability behavior

The use of lower band gap materials such as SiGe for the DG MOSFET channel is of paramount importance given their compatibility with the process developed for pure Silicon devices. Furthermore, the increased electrons mobility in SiGe material has a positive effect on both drain current and transconductance. However, band gap narrowing due to Ge mole fraction increasing channel is a crucial obstacle that leads to electrical performance degradation. Thus, we present in this paper a novel graded doping channel-based approach to enhance the device reliability. Based on Atlas 2-D simulation of the nanoscale SiGe Double Gate MOSFET including the interface defects near the drain side, we develop numerical models to explain the impact of several doping profile on the immunity performance of the nanoscale transistor against the interface traps density. In this context, subthreshold characteristics of the proposed design (threshold voltage, swing factor and gate current) are investigated and evaluated with respect to the conventional uniform doping profile DG MOSFET characteristics.

ANFIS-based computation to study the nanoscale circuit including the hot-carrier and quantum confinement effects

In this paper, we present a new approach based on fuzzy logic for the modeling of the subthreshold swing factor by using the Adaptive Network Fuzzy Inference System (ANFIS). It is also assumed that the nanoscale Double Gate (DG) MOSFET device under study is subject to both hot-carrier and quantum effects. Afterward, an analytical expression is deduced for the transconductance parameter from the subthreshold swing fuzzy model. The developed framework is then adopted as a basis of studying the degradation mechanism of a single transistor amplifier. The obtained results show good agreement with the numerical simulations provided by ATLAS 2D-simulator. The proposed model presented in this paper offers a simple and accurate approach to study the nanoscale CMOS-based circuit behavior including the hot-carrier damage and quantum effects.

ANFIS-based approach to studying subthreshold behavior including the traps effect for nanoscale thin-film DG MOSFETs

A fuzzy framework based on an adaptive network fuzzy inference system (ANFIS) is proposed to evaluate the relative degradation of the basic subthreshold parameters due to hot-carrier effects for nanoscale thin-film double-gate (DG) MOSFETs. The effect of the channel length and thickness on the resulting degradation is addressed, and 2-D numerical simulations are used for the elaboration of the training database. Several membership function shapes are developed, and the best one in terms of accuracy is selected. The predicted results agree well with the 2-D numerical simulations and can be efficiently used to investigate the impact of the interface fixed charges and quantum confinement on nanoscale DG MOSFET subthreshold behavior. Therefore, the proposed ANFIS-based approach offers a simple and accurate technique to study nanoscale devices, including the hot-carrier and quantum effects.

Fuzzy Modeling of Single Machine Scheduling Problems Including the Learning Effect

In this chapter, we consider the single machine scheduling problem including uncertain parameters and position based learning effect with the aim to minimize the weighted sum of jobs completion times. Due to the ill-known quantities within the model, the determination procedures of optimal solutions in the conventional way is not an affordable task and more elaborated frameworks should be developed. In this context, we introduce two solution approaches for the proposed fuzzy scheduling problem in order to obtain an exact or a satisfactory near optimal solution. The first approach is based on the extension of the well-known Smith’s rule resulting in a polynomial algorithm with a complexity O(n l o g(n)). However, a severe constraint on jobs (fuzzy agreeability concept) should be satisfied in this case. The second approach based on optimization methods is built upon the assumption of unequal fuzzy release dates in addition to the absence of fuzzy agreeability constraint. Three trajectory based metaheuristics (Simulated annealing, taboo search and kangaroo search) are implemented and applied to solve the resulting problem. For the proposed methods throughout the chapter, several numerical experimentations jointly with statistical deductions are provided.