Critical Materials, Device Design, Performance and Reliability Issues in 4H-SiC Power Umosfet Structures

1996 ◽  
Vol 423 ◽  
Author(s):  
A. K. Agarwal ◽  
R. R. Siergiej ◽  
S. Seshadri ◽  
M. H. White ◽  
P. G. McMullin ◽  
...  
Keyword(s):  
Electric Field ◽  
Breakdown Voltage ◽  
Gate Insulator ◽  
Limiting Factor ◽  
Mos Capacitor ◽  
Polysilicon Gate ◽  
Critical Materials ◽  
P Type ◽  
High Temperature Operation

AbstractThe long-term reliability of gate insulator under high field stress of either polarity presents a constraint on the highest electric field that can be tolerated in a 4H-SiC UMOSFET under on or off condition. A realistic performance projection of 41H-SiC UMOSFET structures based on electric field in the gate insulator (1.5 MV/cm under on-condition and 3 MV/cm under offcondition) consistent with long-term reliability of insulator is provided for the breakdown voltage in the range of 600 to 1500 V. The use of P+ polysilicon gate allows us to use a higher field of 3 MV/cm in the insulator under off-condition and leads to a higher breakdown voltage as the Fowler Nordheim (FN) injection from the gate electrode is reduced. FN injection data is presented for p type 4H-SiC MOS capacitor under inversion at room temperature and at 325°C. It is concluded that the insulator reliability, and not the SiC, is the limiting factor and therefore the high temperature operation of these devices may not be practical.

scholarly journals Use of Bilayer Gate Insulator in GaN-on-Si Vertical Trench MOSFETs: Impact on Performance and Reliability

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4740
Author(s):  
Kalparupa Mukherjee ◽  
Carlo De Santi ◽  
Matteo Borga ◽  
Shuzhen You ◽  
Karen Geens ◽  
...  
Keyword(s):  
Electric Field ◽  
Breakdown Voltage ◽  
Degradation Process ◽  
Gate Insulator ◽  
Reliability Characteristics ◽  
Vehicle Structure ◽  
Gan On Si ◽  
Module Development ◽  
Bilayer Dielectric ◽  
Good Agreement

We propose to use a bilayer insulator (2.5 nm Al2O3 + 35 nm SiO2) as an alternative to a conventional uni-layer Al2O3 (35 nm), for improving the performance and the reliability of GaN-on-Si semi vertical trench MOSFETs. This analysis has been performed on a test vehicle structure for module development, which has a limited OFF-state performance. We demonstrate that devices with the bilayer dielectric present superior reliability characteristics than those with the uni-layer, including: (i) gate leakage two-orders of magnitude lower; (ii) 11 V higher off-state drain breakdown voltage; and (iii) 18 V higher gate-source breakdown voltage. From Weibull slope extractions, the uni-layer shows an extrinsic failure, while the bilayer presents a wear-out mechanism. Extended reliability tests investigate the degradation process, and hot-spots are identified through electroluminescence microscopy. TCAD simulations, in good agreement with measurements, reflect electric field distribution near breakdown for gate and drain stresses, demonstrating a higher electric field during positive gate stress. Furthermore, DC capability of the bilayer and unilayer insulators are found to be comparable for same bias points. Finally, comparison of trapping processes through double pulsed and Vth transient methods confirms that the Vth shifts are similar, despite the additional interface present in the bilayer devices.

A Comparison of N+ type and P+ type Polysilicon Gate in High Speed Non-Volatile Memories

2007 ◽  
Vol 997 ◽  
Author(s):  
Moon Kyung Kim ◽  
SooDoo Chae ◽  
Chung Woo Kim ◽  
Jo-won Lee ◽  
Sandip Tiwari
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
High Speed ◽  
Silicon Oxide ◽  
Silicon On Insulator ◽  
Polysilicon Gate ◽  
Threshold Voltages ◽  
Strong Localization ◽  
Nitride Oxide ◽  
P Type

AbstractThe polarity of gates and the threshold voltages are primary parameters that determine the electric fields in the gate stack region of non-volatile memories. This field is central to programming, retention and the other characteristics of the devices. We have investigated the effect of the gate polysilicon polarity, experimentally, for silicon-oxide-nitride-oxide-silicon (SONOS) memory devices on silicon-on-insulator (SOI) wafers. An ultra-thin oxide-nitride-oxide (ONO) film with high trap density and strong localization of the trapping provides the scalability and retention in our structures. The effect of ONO film, grown and deposited and of doping was simulated and characterized. Retention is affected by the electric field between the control gate and the storage node. Our experiments and simulations verify the consequences of different polarity of control gates through the change in electric field that they cause in retention and erase times for n+ and p+ polysilicon gate SONOS memories is verified through the characteristic energies of the processes.

Dislocation scatterings in p-type Si1−xGexunder weak electric field

2015 ◽  
Vol 26 (49) ◽  
pp. 495201 ◽  
Author(s):  
Ji-Hyun Hur ◽  
Sanghun Jeon
Keyword(s):  
Electric Field ◽  
Weak Electric Field ◽  
P Type

scholarly journals Long-Term Projections of the Natural Expansion of the Pine Wood Nematode in the Iberian Peninsula

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 849
Author(s):  
Begoña de la Fuente ◽  
Santiago Saura
Keyword(s):  
Iberian Peninsula ◽  
Tree Species ◽  
Average Rate ◽  
Limiting Factor ◽  
Pine Wood Nematode ◽  
Individual Tree ◽  
Pine Wood ◽  
Pine Tree ◽  
Informative Content

The invasive pine wood nematode (PWN), Bursaphelenchus xylophilus, causal agent of pine wilt disease, was first reported in Europe, near Lisbon, in 1999, and has since then spread to most of Portugal. We here modelled the spatiotemporal patterns of future PNW natural spread in the Iberian Peninsula, as dispersed by the vector beetle Monochamus galloprovincialis, using a process-based and previously validated network model. We improved the accuracy, informative content, forecasted period and spatial drivers considered in previous modelling efforts for the PWN in Southern Europe. We considered the distribution and different susceptibility to the PWN of individual pine tree species and the effect of climate change projections on environmental suitability for PWN spread, as we modelled the PWN expansion dynamics over the long term (>100 years). We found that, in the absence of effective containment measures, the PWN will spread naturally to the entire Iberian Peninsula, including the Pyrenees, where it would find a gateway for spread into France. The PWN spread will be relatively gradual, with an average rate of 0.83% of the total current Iberian pine forest area infected yearly. Climate was not found to be an important limiting factor for long-term PWN spread, because (i) there is ample availability of alternative pathways for PWN dispersal through areas that are already suitable for the PWN in the current climatic conditions; and (ii) future temperatures will make most of the Iberian Peninsula suitable for the PWN before the end of this century. Unlike climate, the susceptibility of different pine tree species to the PWN was a strong determinant of PWN expansion through Spain. This finding highlights the importance of accounting for individual tree species data and of additional research on species-specific susceptibility for more accurate modelling of PWN spread and guidance of related containment efforts.

Enhancement of Breakdown Voltage in SOI MOSFET Using Buried p-Type Silicon

2021 ◽  
Author(s):  
Deivakani M ◽  
Sumithra M.G ◽  
Anitha P ◽  
Jenopaul P ◽  
Priyesh P. Gandhi ◽  
...  
Keyword(s):  
Breakdown Voltage ◽  
Impact Ionization ◽  
Semiconductor Industry ◽  
Silicon Layer ◽  
Silicon On Insulator ◽  
Physical Models ◽  
Oxide Semiconductor ◽  
Soi Mosfet ◽  
P Type ◽  
Conventional Device

Abstract Semiconductor industry is still looking for the enhancement of breakdown voltage in Silicon on Insulator (SOI) Metal Oxide Semiconductor Field Effect Transistor (MOSFET). Thus, in this paper, heavy n-type doping below the channel is proposed for SOI MOSFET. Simulation of SOI MOSFET is carried out using 2D TCAD physical simulator. In the conventional device, with no p-type doping is used at the bottom silicon layer. While, in proposed device, p-type doping of 1×1018 cm-3 is used. Physical models are used in the simulation to achieve realistic performance. The models are mobility model, impact ionization model and ohmic contact model. Using TCAD simulation, electron/hole current density, impact generation, recombination and breakdown phenomena are analyzed. It is found that the proposed with p-type doping of 1×1018 cm-3 for SOI MOSFET yields high breakdown voltage. In contrast to conventional device, 20% improvement in breakdown voltage is achieved for proposed device.

scholarly journals F-centers mechanism of long-term relaxation in lead zirconate-titanate based piezoelectric ceramics. 2. After-field relaxation

2016 ◽  
Vol 06 (03) ◽  
pp. 1650019 ◽  
Author(s):  
V. M. Ishchuk ◽  
D. V. Kuzenko
Keyword(s):  
Dielectric Constant ◽  
Electric Field ◽  
Lead Zirconate Titanate ◽  
Oxygen Vacancies ◽  
Lead Zirconate ◽  
Relaxation Processes ◽  
Logarithmic Function ◽  
External Effects ◽  
Dc Electric Field

The paper presents results of experimental study of the dielectric constant relaxation during aging process in Pb(Zr,Ti)O3based solid solutions (PZT) after action of external DC electric field. The said process is a long-term one and is described by the logarithmic function of time. Reversible and nonreversible relaxation process takes place depending on the field intensity. The relaxation rate depends on the field strength also, and the said dependence has nonlinear and nonmonotonic form, if external field leads to domain disordering. The oxygen vacancies-based model for description of the long-term relaxation processes is suggested. The model takes into account the oxygen vacancies on the sample's surface ends, their conversion into [Formula: see text]- and [Formula: see text]-centers under external effects and subsequent relaxation of these centers into the simple oxygen vacancies after the action termination. [Formula: see text]-centers formation leads to the violation of the original sample's electroneutrality, and generate intrinsic DC electric field into the sample. Relaxation of [Formula: see text]-centers is accompanied by the reduction of the electric field, induced by them, and relaxation of the dielectric constant, as consequent effect.

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