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- Daryoosh Dideban

# Daryoosh DidebanUniversity of Kashan · Department of Electrical and Computer Engineering

25.05

· Ph.D. in nanoElectronics, University of Glasgow, UKAbout

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Research Items (44)

- Apr 2019

In recent years, efforts to perform more processing operation on a silicon chip have made a strong enthusiasm for making the circuit components smaller in order to reduce the power and increase the speed. Due to silicon constraints, there will be no possibility to
follow Moore’s law. That’s why we should look for an alternative to silicon. Therefore, due to high mobility, high current density, and low noise, the study on Graphene Nano Ribbon (GNR) began. ADCs and DACs have a major share in the electronics industry.
An ADC prepares signals for the digital world and microprocessor processing. There are different methods for converting analog to digital signals. Among them, due to unique features such as high speed; Flash ADC has attracted the attention of designers. In this
research first, a model for simulating of the GNR field effect transistor (GNRFET), is introduced. Then, this model is used to design a flash ADC. The results of this study indicate that the designed circuit has a desirable performance as an ADC. In addition, compared to a same Si-CMOS sample, errors such as DNL, INL, Offset, and Full scale are reduced. Moreover, GNR-based ADC shows less power consumption. The maximum and minimum power consumption are equal to 27.8% and 17.6% which corresponds to 5-bit and 4-bit GNR-based flash ADCs compared with their CMOS counterpart. Moreover, this research indicates a significant improvement in the delay that is at least 86.3% and maximum 88.6% which corresponds to 5-bit and 3-bit GNR-based flash ADCs.

- Mar 2019

Single electron transistor (SET) is a fast device with promising features in nanotechnology. Its operation speed depends on the island material, so a carbon based material such as graphene nanoribbon (GNR) can be a suitable candidate for using in SET island. The GNR band gap which depends on its width, has a direct impact on the coulomb blockade and SET current. In this research, current–voltage characteristic for the SET utilizing GNR in its island is modelled. The comparison study shows the impact of GNR width and length on the SET current. Furthermore SET quantum capacitance is modeled and effect of GNR width and temperature on the quantum capacitance are investigated.

- Jan 2019

In this paper, we propose three different strategies to estimate the propagation delay time of a nano-CMOS inverter subject to statistical variability. Based on statistical distribution of efficient parameters in the selected compact model, we have reproduced these parameters taking their statistical behavior into account. Since mean and standard deviation (SD) of each parameter and correlation coefficient between parameter pairs are important figures of merit, three strategies are proposed and the accuracies of obtained results using them are evaluated. The first strategy replicates the mean and SD of original parameters but ignores the correlations between them. The second strategy takes mean, SD and the highest correlation coefficient into account while the third strategy considers all of correlations as well as mean and SD of parameters. While the introduced error in the mean of propagation delay time remains negligible between these strategies, the error in the SD can be reached to 16%, 6%, and 3% for no correlation (NC), partial correlation (PC) and full correlation (FC) strategies, respectively.

- Jan 2019

White graphene as a two-dimensional material has honeycomb lattice which is comprised of boron and nitrogen atoms. Its mechanical properties are similar to graphene, but its electrical properties are different because it has a large bandgap about 5.5 eV. Moreover, relaxation time plays a key role in its properties that affects on the electron transfer speed in this material. The white graphene is an insulator, but its dielectric polarization does not depend on the electric field and also any external stress cannot change linear response of relaxation. In this research, some physical properties of white graphene and its relaxation time are investigated and modeled. Finally, acceptable results are reported which bring new hopes for the replacement of silicon oxide with white graphene as a one-monolayer insulator in future sensors applications.

- Jan 2019

Silicene nanoribbon is a one-dimensional structure of monolayer silicon atoms that its energy gap depends on the edge shape and the width of the ribbon. In this paper, we design a Silicene nanoribbon field effect transistor (SiNRFET) based on different ribbon widths and then we compare this structure with a graphene nanoribbon field effect transistor (GNRFET). For this purpose, we study the effect of the parameters such as ribbon length and the number of atoms along the ribbon width. Moreover, we investigate effect of the perpendicular electric field on the Ion/Ioff and transfer characteristics of both structures and compare the performance of these transistors. Finally, we derive the output characteristics of SiNRFET and GNRFET as a function of gate voltage and compare them together. The method that we use in this research is the transfer matrix. The electron wave functions are derived in each region of both transistors in order to obtain the current.

- Dec 2018

The single-electron transistor (SET) principle of operation is based on the Coulomb blockade (CB) phenomenon. The island material and associated defects have a direct impact on the range of the CB effect and the operating speed of the SET. In this research, the impact of vacancy defects on a SET-based on a carbon nanotube (CNT) is investigated. The results show that a SET with six atomic vacancies exhibits the lowest Coulomb diamond area and highest operating speed. The results also show that increasing the distance between two single vacancies decreases the Coulomb diamond area of the SET. Moreover, the location of the vacancies in the CNT and its effect on the operation of the SET are investigated. The comparison study shows that an antidote vacancy in the CNT close to the drain side results in the shortest CB range and narrowest bandgap, resulting in the CNT SET with the highest operating speed.

- Nov 2018

The single electron transistor (SET) is a nanoscale electronic device with fast operation speed. The selection of quantum dot as its island can increase its speed. In this research, fullerene quantum dot is suggested as island of SET and also hydrogen atoms are added to fullerene molecule. Comparison study shows that the number of hydrogen atoms can decrease coulomb blockade and zero current range. Moreover, increasing the number of fullerene quantum dots has an impact on coulomb diamond area, so reliability of SET can be improved. Therefore choosing suitable number of fullerene quantum dots and hydrogen atoms can SET current to a desired value.

- Oct 2018

In this paper, we obtain mechanical properties of monolayer graphene, bilayer graphene and silicene with the aid of molecular dynamics simulation. Thus, the reason for mechanical behavior of these materials is analyzed. For this purpose, first we perform the stress–strain analysis for each structure under tension loading and then we calculate Young’s modulus, tensile strength, and fracture strain of these structures. It is shown that tensile strength of bilayer graphene sheet of type aa is more than type ab and monolayer graphene. Moreover, it is shown that the tensile strength of silicene sheet is less than mono and bilayer graphene. We also investigate the impact of hydrogen functionalization on the mechanical properties of silicene. Hence we consider two situations of random and patterned distribution of hydrogen coating on a silicene sheet. The results indicate that the mechanical properties of the silicene are degraded as a result of functionalizing with hydrogen atoms. It is also revealed that the distribution method of hydrogen atoms affects the strength and fracture strain of hydrogen functionalized silicene.

- Sep 2018

Single electron transistor (SET) is a nano dimension device that is offered by technology to solve the problem of aggressive scaling in traditional transistors. Its operation speed depends on carrier mobility of its quantum dot. In this research, fullerene (C60) and carbon nanotube (CNT) are utilized as materials of quantum dots in SET. Two SETs with different multiple quantum dots as C60-CNT-C60 and CNT-C60-CNT are modeled and analyzed. The comparison study shows that total length of quantum dots as fullerene diameter and CNT length have indirect effect on its current. Moreover increasing temperature decreases its current while rising of the gate voltage increases its current. In other words, quantum dot length, temperature and gate voltage are parameters which can control SET operation. Furthermore two SETs are simulated and their stability diagrams are analyzed. The simulation results show that C60-CNT-C60 SET has lower coulomb blockade and also it has more reliability and faster operation than CNT-C60-CNT SET.

- Aug 2018

In this paper, we propose a scheme of double gate resonant tunneling field effect transistor based on two gates wrapped on a silicene nanotube. By applying a vertical electric field in the side gates, the energy gap in these regions is opened. Due to different bandgap in these regions and other parts of the nanotube, a quantum well is created in the middle which results in confined energy states in the well region. Hence by applying an electric field via lateral gates, we can change the left and right barrier height simultaneously. Moreover, confined states in the well region are tuned by the voltage applied to the central gate. The transmission coefficient of the incident electrons is calculated using the transfer matrix method. Our theoretical results illustrate that the proposed structure has an oscillatory behavior in the transfer characteristics. On the other hand, output characteristic displays a step-like behavior. We also investigate the influence of the barriers and well thicknesses as well as the perpendicular electric field exerted by lateral gates on the current of the proposed device.

- Jul 2018

Graphene single electron transistor (SET) as a coulomb blockade (CB) device operates based on the quantum mechanical effect. Its desired current is achieved by overcoming the CB energy that depends on the total capacitance of SET. Therefore, small size of graphene quantum capacitance is suitable for SET structure because it plays a dominant role in the total capacitance. In this paper, the density of state (DOS) model of graphene SET is suggested because of its important effect on many physical properties. Furthermore, carrier concentration as a key factor in quantum capacitance is modeled. Finally, the quantum capacitance of graphene SET based on the fundamental parameters is modeled and compared to the experimental data, so an acceptable agreement between them is reported. As a result, silicon SET can be replaced with graphene SET because of its lower quantum capacitance and also higher operation speed than the silicon one.

- May 2018

With shrinking transistor dimensions into sub-50-nm regime, statistical variability (SV) causes a great impact on the drain current and threshold voltage of nano-MOSFETs. In this paper, with emphasis on the propagation delay time of an inverter in 35-nm technology node, we have first introduced a strategy to take SV into account in four existing compact models using different number of statistical sets. For each model under study, we identified effective parameters of analytical equations which can be utilized to replicate the impact of SV. Moreover, we analyzed the statistical distribution and correlation of those effective parameters and their impact on the propagation delay time in each model. The results of these statistical CMs are compared with the accurate "atomistic" model, and it is shown that using this approach we can predict the propagation delay time standard deviation with less than 0.2%, 4.1%, 4.8%, and 4.7% errors in different models. However, the mean values of the propagation delay time stay almost constant even by employing statistical sets of single parameters. Furthermore, we study the impact of changing the load capacitance and the supply voltage on the statistical behavior of four models in the presence of SV.

- May 2018

Single-electron transistors (SETs) are nano devices which can be used in low-power electronic systems. They operate based on coulomb blockade effect. This phenomenon controls single-electron tunneling and it switches the current in SET. On the other hand, co-tunneling process increases leakage current, so it reduces main current and reliability of SET. Due to co-tunneling phenomenon, main characteristics of fullerene SET with multiple islands are modelled in this research. Its performance is compared with silicon SET and consequently, research result reports that fullerene SET has lower leakage current and higher reliability than silicon counterpart. Based on the presented model, lower co-tunneling current is achieved by selection of fullerene as SET island material which leads to smaller value of the leakage current. Moreover, island length and the number of islands can affect on co-tunneling and then they tune the current flow in SET.

- Apr 2018

The single electron transistor (SET) as a nanoscale transistor operates according to the electron tunneling via two tunnel junctions. Since selecting a suitable island material plays a key role in electron transfer through the tunnel junctions, in this research capped Carbon NanoTube (CNT) is utilized for the SET island which produces the quantum capacitance (CQ). Its low value decreases the total capacitance (CT). Subsequently the coulomb blockade (CB) energy and the critical temperature are reduced. Moreover the resistance of the capped CNT as a two dimensional material is very low thus its effect on the total resistance can be neglected. The result of an investigation on the capped CNT SET tunnel junction shows that the tunneling time of electron into or out of island decreases therefore the operation speed of capped CNT SET increases. Furthermore both the resistance and the quantum capacitance are modeled and analyzed. Comparison studies of proposed models indicate that the capped CNT length and applied bias voltage play effective roles on the resistance. Additionally the capped CNT SET is simulated and the capped CNT SET stability diagrams are analyzed. The simulation result shows that the lower capped CNT length exhibits a smaller coulomb diamond regions. The lower CB range leads to faster capped CNT SET and a better reliability can be achieved.

- Feb 2018

In this paper, the context of modeling of the impact of mismatch and statistical variations on analogue circuit building blocks is emphasized. The aim is to develop a new algorithm which predicts the statistical behavior of important parameters of an amplifier including output resistance, voltage gain and trans-conductance. The relative error of standard deviation of statistical parameters will remain less than 5% compared with the most accurate Monte-Carlo (MC) simulations using atomistic library model-cards. In comparison with other models which are based on the normal distribution of parameters, the proposed model does not need this limiting presumption. On the other hand, the proposed algorithm is more efficient compared with time consuming MC atomistic simulations.

- Feb 2018

In this paper, with taking advantage of electrical properties of a germanene nanoribbon, we propose a germanene nanoribbon field effect transistor (GeNR-FET). Here by tuning the width and geometry of the germanene nanoribbon in the source, drain and channel regions, we investigate theoretically the transistor characteristics, analog and digital performances of these several different GeNR-FETs at room temperature. Our simulations are obtained using density functional theory (DFT) combined withnon-equilibrium Green's function (NEGF) method. The simulation results show that for digital applications, by tuning the width of the germanene nanoribbon a GeNR-FET with a finite band gap in the channel region and small band gap in the source and drain regions shows a better Ion/Ioff ratio in transfer characteristics. However, for the analog applications, if the band gap of the channel region has small value and the band gap of the source and drain regions have a finite value, the output characteristic shows a higher peak to valley (PVR) ratio which is an important figure of merit in analog applications. Also from the output characteristics, we find that the T-shape channel shows more desirable (PVR) compared with other devices and it reaches to 17.28 in this case.

- Feb 2018

In this study, we investigated and simulated the structure of a quantum well resonant tunneling (QWRT) transistor based on two barriers and a well in the middle. The barriers were formed of semiconductors with a higher bandgap and the well separating the barriers comprised a semimetal-like material with a very small bandgap, i.e., close to zero. The device was positioned on the oxide to exploit the benefits of SOI technology, e.g., improving leakage and the immunity of the device against environment effects. When the well thickness was a few nanometers, the electron-bound states appeared in the quantum well region. By tuning the voltage and work function of the top gate, the bound states moved in the potential well and the carriers were transferred through the well via the resonant tunneling phenomenon. Our simulations showed the step-like behavior of the output characteristics and the oscillatory quantum switching of the transfer characteristics for the proposed device. We also investigated the influence of the well thickness and gate voltage on the device characteristics, and we compared the optimal case with a theoretical analysis of a QWRT transistor based on a topological insulator.

- Jan 2018

With shrinking transistor dimensions into nano meter scale, electrical parameters of transistors become more sensitive against statistical or random variations. Moreover, accurate estimation of these variations using “atomistic simulators” is time consuming and not a cost effective approach. In this paper for the first time, analytical models have been used to study the impacts of statistical variability of fabrication process on propagation delay time in a 35 nm CMOS NAND gate. With selecting appropriate set from analytical model’s parameters, the impact of statistical variability on the propagation delay time have been modeled and extended. Moreover, target analytical model has been benchmarked against statistical variability of fabrication process. The results obtained from extension of this model have been compared with the accurate atomistic simulations. It is observed that by applying different sets of parameters the maximum error of propagation delay time reaches to 8.7% against accurate atomistic simulations but by applying our proposed approach, Standard Deviation (SD) error of propagation delay is estimated to 2.4%. Also the SD error of propagation delay reaches to 9.9% when normal regenerated parameters have been used. Eventually using proposed algorithm which encompasses regenerated Gaussian parameters while taking the correlation factor into account, the SD error decreases to 1.6%.
Keyword(s): STATISTICAL VARIATION, PROPAGATION DELAY TIME, CORRELATION FACTOR, STATISTICAL DISTRIBUTION, NANO-CMOS, ATOMISTIC SIMULATION

- Jan 2018

In this paper, we find transfer characteristics of a Silicene nanotube field effect transistor (SiNTFET) by use of transfer matrix method. The emphasis is to study the impact of factors like channel length, chirality and diameter of a tube that influence the device current. Also, we investigate the impact of electric field on the energy gap, input and output characteristics of SiNTFET and carbon nanotube field effect transistor (CNTFET). Since the energy gap of silicon nanotube changes in the presence of an electric field, this feature causes a SiNTFET has more advantages compared to CNTFET. Our result shows that OFF current strongly depends on the characteristics of the nanotube. Hence the Ion/Ioff is varied by changing the chirality, diameter of the nanotube, and perpendicular electric field. We are exceeding high Ion/Ioff ratio, in the order of 108, by variation of the perpendicular electric field in SiNTFET.

- Dec 2017

In this paper, the impact of statistical variability on the accuracy of a propagation delay time compact model (CM) is analyzed. Hence, we aim to select an appropriate CM and extend it in the presence of statistical variability using a number of electrical parameters. Furthermore, we study the impacts of inverter extrinsic parameters (input transition time, load capacitance), environmental parameters (temperature, supply voltage) and device width on propagation delay time variation. The accuracy of extended propagation delay CM is compared with the most accurate results obtained from a library of “atomistic” modelcards. It is shown that both mean and standard deviation (SD) of the propagation delay time almost follow the trend obtained from “atomistic” simulations while changing device width, extrinsic and environmental parameters. The best accuracy occurs when changing device width (W) and load capacitance (\(C_{L})\). In these cases, a minimum error of 0.03 and 0.01 ps for the mean and SD of the propagation delay time is obtained in reference to “atomistic” results, respectively. The least accuracy occurs when changing \(t_{r}\) and \(C_{L}\). In these cases, a maximum error of 4.2 and 0.48 ps for the mean and SD of propagation delay time is obtained in reference to “atomistic” results, respectively.

- Dec 2017

Here, we compare the output characteristics of a gate-all-around germanium nanowire field effect transistor (GAA-GeNW-FET) with 2.36 nm² square cross-section area using tight-binding (TB) sp³d⁵s* model (full atomistic model (FAM)) and effective mass approximation (EMA). Synopsys/QuantumWise Atomistix ToolKit (ATK) and Silvaco Atlas3D are used to consider the TB model and EMA, respectively. Results show that EMA predicted only one quantum state (QS) for quantum transport, whereas FAM predicted three QSs. A cosine function behavior is obtained by both methods for the first quantum state. The calculated bandgap value by EMA is almost twice smaller than that of the FAM. Also, a fluctuating current is predicted by both methods but in different oscillation values.

- Mar 2017

In this paper, germanium nanowires (GeNWs) with different cross-sectional areas are considered as the channel of a cylindrical surrounding gate field effect transistors (CSG-FETs) and the electronic properties of them are calculated through the density functional method and Slater-Koster (SK) tight binding model. The corresponding transistor parameters are obtained using Non-equilibrium Green’s function (NEGF) combined by SK model. We find that SK model predicts the well-nigh same bandgap value compared to meta-GGA-DFT approximation, while GGA-DFT underestimates the value of the bandgap. CSG-GeNW-FETs Transistor figure of merit shows a supreme Ion/Ioff ratio which is equal to 1012 for one of the considered structures with a circular cross-section. The obtained sub-threshold swing (SS) values for the FETs illustrate an increment trend when the supercell size of the germanium nanowire increases whereas the transconductance and ON-current of the FETs decrease when the GeNW supercell size scales down due to the declining of the density of states and electron transmission spectrum.

- Jan 2017

Two gate-all-around field effect transistors (GAA-FETs) based on carbon and germanium nanotubes are proposed. The electronic properties and analog performance of the FETs are theoretically calculated and compared with each other. Also, by adding 5 × 10¹⁹ dopant/cm² doping concentration in the source and drain regions, the results are re-obtained. Non-equilibrium Green's function method within the tight-binding Hamiltonian, which is extracted from density functional theory through the Wannier function, are used to calculate the output results. From the transfer characteristics analysis for nanotubes with the same chirality, it can be found that the ON- and OFF-currents for GeNTFET is about ten times smaller than that of CNTFET. Moreover, by adding dopants in the source and drain regions, the ION increases for both devices. The ION/IOFF ratio for all proposed FETs is almost the same and it is of order 10⁴. We also found that the subthreshold swing for doped CNTFET is smaller than the other examined devices. The output characteristic of the CNTFET shown a saturation current when the drain voltage reached to 0.4 V, while this value for GeNTFET is equal to 0.6 V. Comparison between CNTFET and GeNTFET with the same chirality shows that the CNTFET has a better transistor performance but when comparing is performed on the same diameter of CNT and GeNT FETs, results show better transistor performance of GeNTFET compared to the CNTFET.

- Nov 2016

In this work, we propose a scheme of the resonant tunneling field effect transistor based on a double ferromagnetic barrier on the surface of a topological insulator. In the proposed structure a quantum well will be created in separation between the barriers and therefore the confined states appear in the quantum well region. By tuning of the confined states with a gate voltage exerted on the well region, the carriers will be transferred through this structure with the resonant tunneling process. Our theoretical analysis illustrates that the transfer characteristics of the proposed resonant tunneling device displayan oscillatory quantum switching on-off behavior with Ion/Ioff which exceeds from 10⁴.It is also shown that the device output characteristic displays a step-like behavior. We also investigate the influence of the well and barrier thicknesses on the transport properties of the device.

- Nov 2016

In this paper, we propose and analyze a graphene tunnelling field effect transistor (GTFET) with a gapped graphene in the channel and gapless graphene in the source/drain regions. Moreover, we compare the performance of this structure with two other monolayer graphene based tunnelling field-effect transistors (GFETs) including gapless and finite band gap graphene across the source, channel and drain regions. We find that the Ion/Ioff ratio in the proposed structure shows a significant promotion compared with two other structures and reaches to 105. Then we investigate the effect of four parameters: doping concentration, drain voltage, dielectric thickness and work function difference between the channel and the gate electrode in the proposed GTFET. It is shown that the ON current and therefore the Ion/Ioff ratio in the proposed structure can be improved by increase of the doping concentration. We also compared the analog performance parameters including the transconductance gm, output conductance gd and voltage gain Av for all three simulated devices. The obtained results show that the proposed GTFET is suitable for analog applications.

- Mar 2016

In this paper, a scheme of the germanene nanoribbon tunneling field effect transistor (GeNR-TFET) is proposed. The characteristics and analog performance of the device were theoretically investigated by exploiting the electrical properties of a germanene nanoribbon and applying the doping concentration in the source and drain regions at 300 K and 4 K temperatures. The device parameters were obtained using a non-equilibrium Green's function (NEGF) method within the tight binding (TB) Hamiltonian. The TB Hamiltonian was extracted from the density functional theory (DFT) through the Wannier function. We find that by increasing the doping concentration the I on current increases which leads to an improvement of the I on/I off ratio to 105. Moreover, decreasing the temperature from 300 K to 4 K causes the I off to become ten times smaller. We find that the device output characteristic displays a negative differential conductance with a good peak-to-valley ratio which is improved by increasing the doping concentration. The analog performance of the device is also investigated in the subthreshold regime of operation by varying the doping concentration. It is observed that by increasing the device doping concentration, the analog figures of merit can be improved.

- Feb 2016

Physisorption of hydrogen molecules on armchair germanene nanoribbon (GeNR) is studied within density functional methods. The adsorption geometries, adsorption energies and transferred charge are obtained. To take the Van der Waals forces into account, the Grimme correction is added to the calculation method. The physisorption effect on the electrical properties of the ribbon is explored as a function of H2 concentration through the Green’s function techniques. Sensing features of the germanene nanoribbon are investigated as a channel of a back gated field effect transistor. The optical properties of the nanoribbon is obtained for parallel and perpendicular polarizations. The results point out that, the germanene is a suitable substrate for H2 encapsulation. Moreover, H2 physisorption can improve the I-V characteristics and suppress the optical spectrum of the germanene nanoribbon. The current through the nanoribbon increases by increasing H2 concentration at the same bias voltage. Also, the germanene back gated FET improve the sensing properties. The results show that the GeNR dielectric function is anisotropic and the germanene nanoribbon becomes more transparent by increasing H2 density. Finally, by applying the spin-orbit coupling (SOC) effect, the obtained results are re-calculated and the changes in the results are studied. The SOC opens up the electronic band gap of the GeNR about 20 meV and increases the current slightly through the GeNR.

- Jan 2016

Abstract In this paper, a top-gated Germanene nanoribbon field effect transistor (GeNR-FET) with and without applying a compressive strain is investigated. Three strain strengths (ε = 3%, 5% and 10%) are applied to the different regions of the proposed GeNR-FET and the obtained transistor characteristics are compared with each other. Moreover, physical and electronic parameters of unstrained and strained GeNR are calculated. The results indicate that the bandgap and electron effective mass of GeNR increase firstly by increasing the strain strength but then decrease and this behavior affects on the transistor figures of merit. We find that the Ion/Ioff ratio and subthreshold swing (SS) of the unstrained FET improves when a 3% compressive strain is applied to the whole of the device. Also, applying a 10% strain to the device increases the ON current of the FET due to strain-induced self-doping behavior, but the obtained transistor parameters for this structure are not very satisfactory. Next, we apply the compressive strain either only to the channel or only to the source and drain of the devices. The obtained results show, due to high lattice mismatch between the channel and the leads, the transistor performance of the strained FETs are almost the same or even worse than that of the unstrained one. A novel engineered device is proposed and the transistor figures of merit and in particular, the analog performance are emphasized. It is found that the new proposed device has a better Ion/Ioff ratio and SS. In addition, negative differential resistance occurs in this transistor. The analog performance of the novel device is obtained and compared with the unstrained and 3% strained GeNR-FET in the subthreshold region. It is observed that the proposed device has a better transconductance and voltage gain so that it is a good candidate for analog applications.

- Dec 2015

In this paper we introduce a novel Silicon on Insulator Metal Oxide Semiconductor Field Effect Transistor (SOI MOSFET) with an embedded silicon heat pass path in the buried oxide (HPP-SOI). As this silicon path in the buried oxide conducts the generated heat in the active silicon channel from the shortest and most efficient path, self-heating effect improves while the fabrication process of this structure will remain without complexity. Moreover, the introduction of dopants in the source side of the channel leads to improvement in the leakage current, subthreshold slope, DIBL and threshold voltage roll-off in comparison with conventional SOI MOSFET (C-SOI). As proposed HPP-SOI structure shows these positive features, this structure can be considered as a serious candidate in nanoscale high temperature integrated applications.

- Oct 2015

We investigate theoretically the possibility of exploiting the electrically tunable band gap property of silicene to achieve field effect transistor with improved characteristics. We find that the silicene field effect transistor where a band gap is introduced through a perpendicular electric field shows a subthreshold swing smaller than 60 mV/decade and a switching effect with high on/off current ratio exceeding (Formula presented.). We find also that the device output characteristic displays a very good saturation due to improved pinch-off of the channel, stemming from the electrically induced band gap.

- May 2015

We propose a scheme for a topological insulator field effect transistor. The idea is based on the gate voltage control of the Dirac fermions in a ferromagnetic topological insulator channel with perpendicular magnetization connecting to two metallic topological insulator leads. Our theoretical analysis shows that the proposed device displays a switching effect with high on/off current ratio and a negative differential conductance with a good peak to valley ratio. (C) 2015 Published by Elsevier B.V.

- Jan 2013

Statistical compact modeling (SCM) is necessary for variability aware design at nanometer regime. An extensive study has been carried out to evaluate the impact of the statistical parameter set selection on the statistical accuracy of two widely used industry standard compact models: BSIM4 and PSP. Different statistical parameter generation strategies have been employed to examine the impact of different statistical parameter selection on both device and circuit simulation accuracy.

- Oct 2010
- Custom Integrated Circuits Conference (CICC), 2010 IEEE

Statistical variability associated with discreteness of charge and granularity of matter is one of limiting factors for CMOS scaling and integration. The major MOSFET statistical variability sources and corresponding physical simulations are discussed in detail. Direct statistical parameter extraction approach is presented and the scalability of 6T and 8T SRAM of bulk CMOS technology is investigated. The standard statistical parameter generation approaches are benchmarked and newly developed parameter generation approach based on nonlinear power method is outlined.

- Oct 2010
- Simulation of Semiconductor Processes and Devices (SISPAD), 2010 International Conference on

Statistical variability (SV) is one of the fundamental limiting factors for future nano- CMOS scaling and integration of. Variability aware design is essential to achieve reasonable yield and reliability in the manufacture of circuit and systems. To develop effective variability aware design technologies it is essential to have a reliable and accurate statistical compact modeling strategy. In this study a nonlinear power method (NPM) based statistical compact modeling strategy is presented. The results indicate that statistical compact model parameters generated by a NPM approach are significantly better at capturing the tails and non-normal shape of statistical parameter distributions when compared with principal component analysis (PCA).

- Jun 2010
- Electrical Engineering (ICEE), 2010 18th Iranian Conference on

In this paper the capacitance components of the PSP compact model which is selected as successor of BSIM4 by the Compact Modelling Council (CMC) are investigated and simulated in HSPICE for the state of the art 35nm MOSFET device. The simulations are compared with TCAD results in both transcapacitance components between the device terminals and time domain to show the impact of accuracy of compact model on real circuit simulations.

- May 2010

The strategy to generate statistical model parameters is essential for variability-aware design. Based on 3D atomistic simulation results, this article evaluates the accuracy of statistical parameter generation for two industry-standard compact device models.

- Mar 2010
- Design, Automation and Test in Europe, DATE 2010, Dresden, Germany, March 8-12, 2010

Statistical variability (SV) presents increasing challenges to CMOS scaling and integration at nanometer scales. It is essential that SV information is accurately captured by compact models in order to facilitate reliable variability aware design. Using statistical compact model parameter extraction for the new industry standard compact model PSP, we investigate the accuracy of standard statistical parameter generation strategies in statistical circuit simulations. Results indicate that the typical use of uncorrelated normal distribution of the statistical compact model parameters may introduce considerable errors in the statistical circuit simulations.

- Jan 2010

Intrinsic statistical variability (SV) associated with discreteness of charge and granularity of matter is one of limiting factors for CMOS scaling and integration. There are several standard statistical parameter generation strategies to transfer SV information into compact models, and their accuracy is essential for achieving reliable variability aware design. We investigate the accuracy of these strategies based on the direct statistical compact model parameter extraction results for industry standard compact models BSIM4 and PSP. Statistical circuit simulation results indicate that the standard assumption for uncorrelated normal distribution of the statistical compact model parameters may introduce considerable errors in the statistical distribution of circuit figure of merits.

Statistical variability is a major challenge for CMOS scaling and integration. In order to achieve variability aware design, it's critical important to reliably transfer device characteristics statistical variability information into compact models. A PCA based statistical compact modeling strategy is benchmarked against 'atomistic' device simulation and direct statistical parameter extraction strategy. The results indicate that PCA based approach may introduce considerable error in tail of distribution, which in turn may generate pessimistic or optimistic conclusions in statistical circuit simulation

In this research an emerging field of power electronics in nanotechnology is survived. This application-based technology today is called Nano Power Electronics. It utilizes nano electronic transistors in switching applications in the range of nano power for signal shaping purposes. In recent years Single Electron Transistors are highly interested in nano electronic applications. They have got inherently fast tunneling rate, which makes them highly suitable for high-speed operation. Based on this fact, a novel nano DC/AC converter nano inverter is proposed with these transistors. Simulation of this integrated nano inverter with SPICE shows it has excellent output waveforms and it will be a good candidate for nano power electronic applications.