SiC Trenched Schottky Diode with Step-Shaped Junction Barrier for Superior Static Performance and Large Design Window

A novel silicon carbide (SiC) trenched schottky diode with step-shaped junction barrier is proposed for superior static performance and large design window. In the proposed diode, to improve tradeoff between specific on-resistance and surface peak electric field, the shape of the trenched-junction is modified to stair-step, without extra fabrication process. To investigate the performances of the SiC step-shaped trenched junction barrier schottky (SSTJBS) diode, numerical simulations are carried out through Silvaco TCAD. The results indicate that the proposed diode can accommodate highly doped drift region with no degradation of its reverse blocking characteristic. In comparison with the conventional SiC trenched junction barrier schottky (TJBS) diode, the proposed SiC SSTJBS diode shows a larger design window of drift region doping concentration from 7.9×1015cm-3 to 9.5×1015cm-3. In the design window, the specific on-resistance and surface peak electric field can be reduced by 12.9% and 11%, respectively.

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Study of 4H-SiC Schottky Diode Designs for 3.3kV Applications

Materials Science Forum ◽

10.4028/www.scientific.net/msf.778-780.795 ◽

2014 ◽

Vol 778-780 ◽

pp. 795-799 ◽

Cited By ~ 12

Author(s):

Holger Bartolf ◽

Vinoth Kumar Sundaramoorthy ◽

Andrei Mihaila ◽

Maxime Berthou ◽

Philippe Godignon ◽

...

Keyword(s):

Electric Field ◽

Numerical Simulations ◽

Schottky Diode ◽

Schottky Diodes ◽

High Electric Field ◽

Avalanche Breakdown ◽

Edge Termination ◽

Static Performance ◽

Interfacial Charge

The static performance of different active and termination area designs for SiC-based Schottky diodes, suitable for 3.3kV applications, were investigated by means of extensive numerical simulations. We found quantitatively that the high electric field of SiC close to avalanche-breakdown is shielded most effectively from the Schottky interface by a trench-based design. Moreover, we conclude that the edge termination design with junction termination extension and four implantedp+guard rings is most robust against oxide interfacial charge.

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Interface Trap Density and Mobility Characterization of Silicon Carbide MOSFET Inversion Layers

Materials Science Forum ◽

10.4028/www.scientific.net/msf.615-617.801 ◽

2009 ◽

Vol 615-617 ◽

pp. 801-804 ◽

Cited By ~ 2

Author(s):

Vinayak Tilak ◽

Kevin Matocha ◽

Greg Dunne

Keyword(s):

Silicon Carbide ◽

Electric Field ◽

Doping Concentration ◽

Phonon Scattering ◽

Field Effect Transistors ◽

Inversion Layer ◽

Oxide Semiconductor ◽

Conduction Band Edge ◽

Interface Trap ◽

Surface Electric Field

Silicon Carbide (SiC) based metal oxide semiconductor field effect transistors (MOSFETs) were fabricated and characterized using gated hall measurements with different p-type substrate doping concentration (7.2X1016cm-3 and 2X1017 cm-3). An interface trap state density of 5X1013 cm-2eV-1 was observed nearly 0.1 eV above the conduction band edge leading to the conclusion that these states are present in the silicon dioxide rather than the interface. The Hall mobility of the MOSFETs decreased from 26.5 to 20 cm2/Vs as the doping was increased from 7.2X1016 to 2X1017cm-3. The decrease in mobility is primarily due to an increase in the surface electric field that causes an increase in surface roughness scattering. The inversion layer mobility when plotted as a function of average surface electric field is not independent of doping concentration as is the case in silicon MOSFETs because the dominant scattering mechanism is not phonon scattering.

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Process Variation Tolerant 4H-SiC Power Devices Utilizing Trench Structures

Materials Science Forum ◽

10.4028/www.scientific.net/msf.740-742.809 ◽

2013 ◽

Vol 740-742 ◽

pp. 809-812 ◽

Cited By ~ 1

Author(s):

Hossein Elahipanah ◽

Arash Salemi ◽

Benedetto Buono ◽

Carl Mikael Zetterling ◽

Mikael Östling

Keyword(s):

Silicon Carbide ◽

Breakdown Voltage ◽

High Voltage ◽

Doping Concentration ◽

Process Variation ◽

Process Variations ◽

Fabrication Process ◽

Power Devices ◽

Voltage Variation ◽

Conventional Structure

Silicon carbide (SiC) is one of the most attractive semiconductors for high voltage applications. The breakdown voltage of SiC-based devices highly depends on the variation of the fabrication process including doping of the epilayers and the etching steps. In this paper, we show a way to diminish this variability by employing novel trench structures. The influence of the process variations in terms of doping concentration and etching has been studied and compared with conventional devices. The breakdown voltage variation (ΔVBR) of 450 V and 2100 V is obtained for the ±20% variation of doping concentration of the devices with and without the trench structures, respectively. For ±20% variation in etching steps, the maximum ΔVBR of 380 V is obtained for the device with trench structures in comparison to 1800 V for the conventional structure without trench structures. These results show that the breakdown voltage variation is significantly reduced by utilizing the proposed structure.

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Improving Linearity and Robustness of RF LDMOS by Mitigating Quasi-Saturation Effect

Active and Passive Electronic Components ◽

10.1155/2019/8425198 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7

Author(s):

Haifeng Mo ◽

Yaohui Zhang ◽

Helun Song

Keyword(s):

Electric Field ◽

Electron Velocity ◽

Drift Region ◽

Electron Hole ◽

Velocity Saturation ◽

Root Cause ◽

Turn On ◽

Saturation Region ◽

First Time ◽

Peak Electric Field

This paper discusses linearity and robustness together for the first time, disclosing a way to improve them. It reveals that the nonlinear transconductance with device working at quasi-saturation region is significant factor of device linearity. The peak electric field is the root cause of electron velocity saturation. The high electric field at the drift region near the drain will cause more electron-hole pairs generated to trigger the parasitic NPN transistor turn-on, which may cause failure of device. Devices with different drift region doping are simulated with TCAD and measured. With LDD4 doping, the peak electric field in the drift region is reduced; the linear region of the transconductance is broadened. The adjacent channel power ratio is decreased by 2 dBc; 12% more power can be discharged before the NPN transistor turn-on, indicating a better linearity and robustness.

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The IMOSFET: A Deeply-Scaled Fully-Self-Aligned Trench MOSFET

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1004.751 ◽

2020 ◽

Vol 1004 ◽

pp. 751-757

Author(s):

Madankumar Sampath ◽

Arash Salemi ◽

Dallas Morisette ◽

James A. Cooper

Keyword(s):

Silicon Carbide ◽

Fabrication Process ◽

Drift Region ◽

Cell Area ◽

Power Mosfets ◽

Great Progress ◽

A Cell

Silicon Carbide (SiC) power MOSFETs have made great progress since the first commercial devices were introduced in 2011, but they are still far from theoretical limits of performance. Above ~1200 V the specific on-resistance is limited by the drift region, but below 1200 V the resistance is dominated by the channel and the substrate, with smaller contributions from the source and the JFET regions. Trench MOSFETs generally have smaller cell area than planar DMOSFETs and are inherently more scalable. In this paper, we describe a highly self-aligned fabrication process to realize deeply-scaled trench MOSFETs with a cell pitch of 0.5 μm per channel. Since the narrow gate trench is shaped like a letter “I”, we refer to these devices as “IMOSFETs.”

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Numerical Simulations of Electric Field Driven Self-Assembly of Monolayers of Mixtures of Nanoparticles

Volume 1B, Symposia: Fluid Measurement and Instrumentation; Fluid Dynamics of Wind Energy; Renewable and Sustainable Energy Conversion; Energy and Process Engineering; Microfluidics and Nanofluidics; Development and Applications in Computational Fluid Dynamics; DNS/LES and Hybrid RANS/LES Methods ◽

10.1115/fedsm2017-69380 ◽

2017 ◽

Author(s):

E. Amah ◽

N. Musunuri ◽

Ian S. Fischer ◽

Pushpendra Singh

Keyword(s):

Electric Field ◽

Physical Properties ◽

Numerical Simulations ◽

Self Assembly ◽

Composite Particle ◽

Critical Value ◽

Direct Numerical Simulations ◽

Composite Particles ◽

Liquid Interfaces ◽

Induced Dipole

We numerically study the process of self-assembly of particle mixtures on fluid-liquid interfaces when an electric field is applied in the direction normal to the interface. The force law for the dependence of the electric field induced dipole-dipole and capillary forces on the distance between the particles and their physical properties obtained in an earlier study by performing direct numerical simulations is used for conducting simulations. The inter-particle forces cause mixtures of nanoparticles to self-assemble into molecular-like hierarchical arrangements consisting of composite particles which are organized in a pattern. However, there is a critical electric intensity value below which particles move under the influence of Brownian forces and do not self-assemble. Above the critical value, when the particles sizes differed by a factor of two or more, the composite particle has a larger particle at its core and several smaller particles forming a ring around it. Approximately same sized particles, when their concentrations are approximately equal, form binary particles or chains (analogous to polymeric molecules) in which positively and negatively polarized particles alternate, but when their concentrations differ the particles whose concentration is larger form rings around the particles with smaller concentration.

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Electrokinetic instability due to streamwise conductivity gradients in microchip electrophoresis

Journal of Fluid Mechanics ◽

10.1017/jfm.2021.672 ◽

2021 ◽

Vol 925 ◽

Author(s):

Kaushlendra Dubey ◽

Sanjeev Sanghi ◽

Amit Gupta ◽

Supreet Singh Bahga

Keyword(s):

Electric Field ◽

Numerical Simulations ◽

Electric Fields ◽

Quantitative Measure ◽

Underlying Mechanism ◽

Scaling Analysis ◽

Recirculating Flow ◽

Electrokinetic Instability ◽

Spatial Features ◽

Proper Orthogonal Decomposition Technique

We present an experimental and numerical investigation of electrokinetic instability (EKI) in microchannel flow with streamwise conductivity gradients, such as those observed during sample stacking in capillary electrophoresis. A plug of a low-conductivity electrolyte solution is initially sandwiched between two high-conductivity zones in a microchannel. This spatial conductivity gradient is subjected to an external electric field applied along the microchannel axis, and for sufficiently strong electric fields an instability sets in. We have explored the physics of this EKI through experiments and numerical simulations, and supplemented the results using scaling analysis. We performed EKI experiments at different electric field values and visualised the flow using a passive fluorescent tracer. The experimental data were analysed using the proper orthogonal decomposition technique to obtain a quantitative measure of the threshold electric field for the onset of instability, along with the corresponding coherent structures. To elucidate the physical mechanism underlying the instability, we performed high-resolution numerical simulations of ion transport coupled with fluid flow driven by the electric body force. Simulations reveal that the non-uniform electroosmotic flow due to axially varying conductivity field causes a recirculating flow within the low-conductivity region, and creates a new configuration wherein the local conductivity gradients are orthogonal to the applied electric field. This configuration leads to EKI above a threshold electric field. The spatial features of the instability predicted by the simulations and the threshold electric field are in good agreement with the experimental observations and provide useful insight into the underlying mechanism of instability.

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