Synopsys Sentaurus TCAD Research Articles

Analysis and Performance Study of III–V Schottky Barrier Double-Gate MOSFETs Using a 2-D Analytical Model

A comprehensive study and comparison of IV and III–V Schottky barrier (SB) double-gate MOSFETs using a universal analytical model and Synopsys TCAD Sentaurus is presented. Various impacts on the device performance have been identified, e.g., the SB height, the bandgap, the material-dependent carrier masses, and density-of-states affecting the ambipolar behavior and ON-current. The performance is analyzed with respect to the most important physical parameters and their impact on the device figure of merit. Ambipolar behavior is an important factor and must be carefully considered in the device design to aim a high $I_{\mathrm{\scriptscriptstyle ON}}/I_{\mathrm{\scriptscriptstyle OFF}}$ ratio and comparable subthreshold slope to conventional MOSFET devices to benefit from the SB. This paper shows that the above listed parameters determine the bottleneck on the device performance.

Al+ implanted vertical 4H-SiC p-i-n diodes: experimental and simulated forward current-voltage characteristics

ABSTRACT The temperature dependence of the forward and reverse current voltage characteristics of circular Al+ implanted 4H-SiC p-i-n vertical diodes of various diameters, post implantation annealed at 1950 °C/5 min, have been used to obtain the thermal activation energies of the defects responsible of the generation and the recombination currents, as well as the area and the periphery current component of the current voltage characteristics. The former have values compatible with those of the traps associated to the carbon vacancy defect in 4H-SiC. The hypothesis that only these traps may justify the trend of the current voltage characteristics of the studied diodes has been tested by simulations in a Synopsys Sentaurus TCAD suite.

Effect of Wideband Gap Tunnel Diode and Thickness of the Window Layer on the Performance of a Dual Junction Solar Cell

Multi junction solar cells made up of III-V compound semiconductor has not achieved an optimized result yet. Tunnel diode plays an important role in the design of a highly efficient multi junction solar cell as it act as an interconnect layer between different sub cells. In this work we have investigated the effect of use of wideband gap tunnel diode and the window layer thickness on the performance of an InGaP/GaAs dual junction solar cell. The analysis is done under AM 1.5G spectrum using Synopsys Sentaurus TCAD. The electrical properties like external quantum efficiency, internal quantum efficiency, short circuit current density, open circuit voltage, spectral current density, and reflectance are examined and compared with GaAs tunnel diode solar cell. The conversion efficiency of the optimized cell is found to be 33.30%.

Investigation of fill factor losses on 20.2% efficient n‐type mono‐like silicon solar cells with laser contact opening

Large area (243.36 cm2) back‐junction passivated emitter, rear totally diffused (PERT) solar cells with laser contact opening (LCO) on n‐type mono‐like crystalline Si with efficiencies of 20.2% are presented. Boron emitters with high electrical quality (implied open circuit voltage iVOC up to 700 mV) are formed during a co‐diffusion step using SiOx:B layers. Increasing the rear metal contact coverage, we observed a decrease in fill factor (FF) instead of the expected increase due to the decrease of the back side series resistance. We show that it can be attributed to recombination centers (RCs) in the space charge region underneath the contact spots inducing an increasing second diode contribution. The presented empirical model for the RCs implemented in Synopsys Sentaurus TCAD allows for a successful reproduction of the FF, pseudo FF and VOC behaviour with contact coverage. According to this model, the RCs induced by laser ablation and subsequently evaporation of Al have a shallow exponential distribution with a characteristic length of LT = 0.2 µm and an effective surface density of N *T0 = 25 cm–1. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)

Simulation of the impact of heavy charged particles on the characteristics of field-effect silicon-on-insulator transistors

A technique for numerical simulation of variation in the drain current in a silicon-on-insulator field-effect transistor with indirect gate caused by the impact of a heavy charged particle is discussed. The SRIM software and the Synopsys TCAD Sentaurus software suite for process and device simulation are used for simulation. The obtained results are used for formulation of the guidelines on selection of the transistor geometry are formulated based on.

Modeling of radiation damage recovery in particle detectors based on GaN

The pulsed characteristics of the capacitor-type and PIN diode type detectors based on GaN have been simulated using the dynamic and drift–diffusion models. The drift–diffusion current simulations have been implemented by employing the commercial software package Synopsys TCAD Sentaurus. The bipolar drift regime has been analyzed. The possible internal gain in charge collection through carrier multiplication processes determined by impact ionization has been considered in order to compensate carrier lifetime reduction due to radiation defects introduced into GaN material of detector.

A method to simulate the observed surface properties of proton irradiated silicon strip sensors

During the scheduled high luminosity upgrade of the LHC, the world's largest particle physics accelerator at CERN, the position sensitive silicon detectors installed in the vertex and tracking part of the CMS experiment will face a more intense radiation environment than the present system was designed for. To upgrade the tracker to the required performance level, extensive measurements and simulation studies have already been carried out. A defect model for the bulk properties of proton irradiated silicon has been created with the Synopsys Sentaurus TCAD simulation package which produces simulated results that closely match the measured properties of silicon strip detectors. However, the expected behaviour due to increased surface damage is not so well predicted by the model. The solution requires an approach that does not affect the accurate bulk properties produced by the proton model, but only adds to it the required radiation induced properties close to the surface. These include the observed position dependence of the strip detector's charge collection efficiency (CCE). In this paper a procedure to find a defect model that reproduces the correct CCE loss, along with other surface properties of a strip detector up to a fluence 1.5×1015 1 MeV neq cm−2 (Φeq), will be presented. When applied to CCE loss measurements at different fluences, this method may provide a means for the parametrization of the accumulation of oxide charge at the SiO2/Si interface as a function of dose.

Schottky Body Diode를 집적하여 향상된 Reverse Recovery 특성을 가지는 50V Power MOSFET

In this paper, 50V power U-MOSFET which replace the body(PN) diode with Schottky is proposed. As already known, Schottky diode has the advantage of reduced reverse recovery loss than PN diode. Thus, the power MOSFET with integrated Schottky integrated can minimize the reverse recovery loss. The proposed Schottky body diode U-MOSFET(SU-MOS) shows reduction of reverse recovery loss with the same transfer, output characteristic and breakdown voltage. As a result, 21.09% reduction in peak reverse current, 7.68% reduction in reverse recovery time and 35% improvement in figure of merit(FOM) are observed when the Schottky width is and the Schottky barrier height is 0.8eV compared to conventional U-MOSFET(CU-MOS). The device characteristics are analyzed through the Synopsys Sentaurus TCAD tool.

Simulations of operation dynamics of different type GaN particle sensors.

The operation dynamics of the capacitor-type and PIN diode type detectors based on GaN have been simulated using the dynamic and drift-diffusion models. The drift-diffusion current simulations have been implemented by employing the software package Synopsys TCAD Sentaurus. The monopolar and bipolar drift regimes have been analyzed by using dynamic models based on the Shockley-Ramo theorem. The carrier multiplication processes determined by impact ionization have been considered in order to compensate carrier lifetime reduction due to introduction of radiation defects into GaN detector material.

Charge collection efficiency simulations of irradiated silicon strip detectors

During the scheduled high luminosity upgrade of LHC, the world's largest particle physics accelerator at CERN, the position sensitive silicon detectors installed in the vertex and tracking part of the CMS experiment will face a more intense radiation environment than the present system was designed for. Thus, to upgrade the tracker to the required performance level, comprehensive measurements and simulation studies have already been carried out.Essential information of the performance of an irradiated silicon detector is obtained by monitoring its charge collection efficiency (CCE). From the evolution of CCE with fluence, it is possible to directly observe the effect of the radiation induced defects on the ability of thedetector to collect charge carriers generated by traversing minimum ionizing particles (MIPs).In this paper the numerically simulated CCE and CCE loss between the strips of irradiated silicon strip detectors are presented. The simulations based on the Synopsys Sentaurus TCAD framework were performed before and after irradiation for fluences up to 1.5 × 1015 neqcm−2 for n-on-p sensors. A two level defect model and non-uniform three level defect model were applied for the proton irradiation simulations, and a two levelmodel for neutrons. The results are presented together with the measurements of strip detectorsirradiated by different particles and fluences and show considerable agreement for both CCE and its position dependency.

Simulation of Si and GaAs submicron TRAPATT diodes

Plasma formation and extraction processes in submicron silicon N + NP + , GaAs N + NP + , and GaAs NM Schottky TRAPATT (TRApped Plasma Avalanche Triggered Transit) diodes were simulated. The simulation of GaAs TRAPATT diodes was done for the first time. The quasi-hydrodynamic model was chosen for the simulation of the processes. The Synopsys TCAD Sentaurus Software Package was used. The carrier mobility dependence on phonon scattering, impurity scattering, carrier-carrier scattering, intervalley scattering (for GaAs), and mobility saturation in a high electric field was taken into account. Several generation-recombination mechanisms were included: impact ionization, Shockley–Read–Hall recombination (SRH) with doping-dependent lifetimes, trap-assisted tunnelling, band-to-band tunnelling, Auger recombination, and radiative recombination (for GaAs). We show that the so-called critical current density for plasma formation in the submicron diodes increases with the active layer thickness decrease and almost does not depend on the doping density in the active layer. The critical current density for silicon diodes is about two times lower than for the GaAs diodes. The intensive minority carrier storage in the N + and P + regions has a high influence on the voltage oscillation amplitude and frequency after the first plasma formation and extraction period. Oscillation damping takes place in the N + NP + GaAs diode with the active layer thickness of less than 0.3 µm.

Fast 3-D Electrothermal Device/Circuit Simulation of Power Superjunction MOSFET Based on SDevice and HSPICE Interaction

Automated interaction of SDevice and HSPICE for fast 3-D electrothermal simulation based on the relaxation method is designed. The results are compared with device finite element model simulation and a direct method with an equivalent thermal 3-D RC network. The features and limitations of the methods are analyzed and presented. The designed electrothermal simulation based on the relaxation method is developed for Synopsys TCAD Sentaurus environment for decreasing the simulation time for complex 3-D devices. A power vertical superjunction MOSFET under an unclamped inductive switching test of device robustness is used to perform validation of the designed electrothermal simulation.

Performance Study of a Schottky Barrier Double-Gate MOSFET Using a Two-Dimensional Analytical Model

A comprehensive study of the impact of the Schottky barrier height, affecting the ambipolar behavior of Schottky barrier double-gate MOSFETs using an analytical model and Synopsys TCAD Sentaurus, is presented. The performance is analyzed with respect to the most important physical parameters and their impact on the device figure-of-merit. Ambipolar behavior is an important factor and must be carefully considered in the device design. This brief shows that the Schottky barrier height plays a very important role and determines the bottleneck on the device performance.

Modeling and Design of a Thin-Film CdTe/Ge Tandem Solar Cell

Thin-film cadmium telluride (CdTe) solar cells have found widespread application, with current commercially available module efficiencies reaching 14.4% and production costs falling as low as \( \hbox{US}\,\$0.75/W_{\rm p}\). Despite the proliferation of this technology, there have been comparatively few developments in research circles in recent years. Rather than attempt to further advance the materials science of CdTe solar cells, it is proposed to realize an efficiency improvement over conventional cells by means of a novel tandem structure. Three such structures are examined herein, and results of simulation using Synopsys Sentaurus TCAD are presented.

Dependence of Electrical Characteristics on the Depth of the Recess Region in the Scaled Tantalum Nitride–Aluminum Oxide–Silicon Nitride–Silicon Oxide–Silicon Flash Memory Devices

Nanoscale tantalum nitride–aluminum oxide–silicon nitride–silicon oxide–silicon (TANOS) memory devices utilizing a recess region were investigated to improve device performance and reduce cell-to-cell interference. The dependence of electrical properties on the depth of the recess region in the TANOS flash memory devices was simulated by using Synopsys TCAD Sentaurus. The cell-to-cell interference characteristics of the TANOS flash memory devices dependent on the recess region were investigated. The drain current at an on-state in the TANOS flash memory devices increased with increasing depth of the recess region owing to the existence of the fringe field generated from the recess region. The coupling ratio of the TANOS flash memory increased with increasing depth of the recess region. The simulation results showed that the cell-to-cell interference in the TANOS flash memory devices decreased with increasing depth of the recess region.

Simulation of femtosecond pulsed laser effects on MOS electronics using TCAD Sentaurus customized models

AbstractPulsed laser illumination constitutes an excellent tool to emulate the effects produced by the impact of highly energetic particles on electronic circuits. Numerical simulation techniques could be used to study these effects and to establish accurate relationships between the laser parameters and the particle characteristics. Unfortunately, although particle incidence can be accurately simulated, up to now, there not exist a simulation technique able to reproduce completely the effects in electronics produced by a femtosecond pulsed laser. In this paper, we explore the Synopsys Sentaurus TCAD ability to simulate the effects of pulsed laser illumination. Theoretical study of the physics of the laser–semiconductor interactions leads us to design a new simulation tool. Modifying the heavy ion generation rate included in Sentaurus TCAD, we can take into account all the theoretical predicted characteristics of femtosecond laser illumination, and reproduce the single event effects (SEE) found in experimental tests. Copyright © 2010 John Wiley & Sons, Ltd.

Modeling the operation of field-effect transistors based on GaAs/AlGaAs heterostructures

The parameters of a structure consisting of a doped GaAs channel and an AlGaAs buffer located between the substrate and the channel are optimized using the Synopsys Sentaurus TCAD simulator. It is shown that the use of this buffer increases the breakdown voltage and power of the transistor compared to the basic structure transistor without an AlGaAs buffer. It is also shown that the transistor breakdown voltage is most greatly affected by the buffer composition (the fraction of aluminum in the AlxGa1−xAs) solid solution and, that the maximum breakdown voltage is obtained for a buffer containing no less than 18% aluminum.

Simulation of 4H-SiC MESFET for High Power and High Frequency Response

In this paper, we report an analytical modeling and 2-D Synopsys Sentaurus TCAD simulation of ion implanted silicon carbide MESFETs. The model has been developed to obtain the threshold voltage, drain-source current, intrinsic parameters such as, gate capacitance, drain-source resistance and transconductance considering different fabrication parameters such as ion dose, ion energy, ion range and annealing effect parameters. The model is useful in determining the ion implantation fabrication parameters from the optimization of the active implanted channel thickness for different ion doses resulting in the desired pinch off voltage needed for high drain current and high breakdown voltage. The drain current of approximately 10 A obtained from the analytical model agrees well with that of the Synopsys Sentaurus TCAD simulation and the breakdown voltage approximately 85 V obtained from the TCAD simulation agrees well with published experimental results. The gate-to-source capacitance and gate-todrain capacitance, drain-source resistance and transconductance were studied to understand the device frequency response. Cut off and maximum frequencies of approximately 10 ㎓ and 29 ㎓ respectively were obtained from Sentaurus TCAD and verified by the Smith’s chart.