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.

scholarly journals Understanding the Leakage Mechanisms and Breakdown Limits of Vertical GaN-on-Si p+n−n Diodes: The Road to Reliable Vertical MOSFETs

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 445
Author(s):  
Kalparupa Mukherjee ◽  
Carlo De Santi ◽  
Matteo Buffolo ◽  
Matteo Borga ◽  
Shuzhen You ◽  
...  
Keyword(s):  
Electric Field ◽  
Breakdown Voltage ◽  
Doping Concentration ◽  
Temperature Dependent ◽  
Trade Off ◽  
The Road ◽  
Current Voltage ◽  
Gan On Si ◽  
The Impact ◽  
Tcad Simulations

This work investigates p+n−n GaN-on-Si vertical structures, through dedicated measurements and TCAD simulations, with the ultimate goal of identifying possible strategies for leakage and breakdown optimization. First, the dominant leakage processes were identified through temperature-dependent current–voltage characterization. Second, the breakdown voltage of the diodes was modelled through TCAD simulations based on the incomplete ionization of Mg in the p+ GaN layer. Finally, the developed simulation model was utilized to estimate the impact of varying the p-doping concentration on the design of breakdown voltage; while high p-doped structures are limited by the critical electric field at the interface, low p-doping designs need to contend with possible depletion of the entire p-GaN region and the consequent punch-through. A trade-off on the value of p-doping therefore exists to optimize the breakdown.

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 Simulation of Thermal and Electric Field Distribution in Packaged Sausages Heated in a Stationary Versus a Rotating Microwave Oven

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1622
Author(s):  
Wipawee Tepnatim ◽  
Witchuda Daud ◽  
Pitiya Kamonpatana
Keyword(s):  
Temperature Distribution ◽  
Electric Field ◽  
Three Dimensional ◽  
Development Stage ◽  
Microwave Oven ◽  
Computational Time ◽  
Plastic Package ◽  
Heating Uniformity ◽  
The Cost ◽  
Good Agreement

The microwave oven has become a standard appliance to reheat or cook meals in households and convenience stores. However, the main problem of microwave heating is the non-uniform temperature distribution, which may affect food quality and health safety. A three-dimensional mathematical model was developed to simulate the temperature distribution of four ready-to-eat sausages in a plastic package in a stationary versus a rotating microwave oven, and the model was validated experimentally. COMSOL software was applied to predict sausage temperatures at different orientations for the stationary microwave model, whereas COMSOL and COMSOL in combination with MATLAB software were used for a rotating microwave model. A sausage orientation at 135° with the waveguide was similar to that using the rotating microwave model regarding uniform thermal and electric field distributions. Both rotating models provided good agreement between the predicted and actual values and had greater precision than the stationary model. In addition, the computational time using COMSOL in combination with MATLAB was reduced by 60% compared to COMSOL alone. Consequently, the models could assist food producers and associations in designing packaging materials to prevent leakage of the packaging compound, developing new products and applications to improve product heating uniformity, and reducing the cost and time of the research and development stage.

scholarly journals 60 GHz Double Deck T-Gate AlN/GaN/AlGaN HEMT for V-Band Satellites

2021 ◽  
Author(s):  
A.S. Augustine Fletcher ◽  
D Nirmal ◽  
J Ajayan ◽  
L Arivazhagan ◽  
Husna Hamza K ◽  
...  
Keyword(s):  
Electric Field ◽  
Breakdown Voltage ◽  
Figure Of Merit ◽  
Drain Current ◽  
60 Ghz ◽  
Mechanical Reliability ◽  
Gan Hemt ◽  
V Band ◽  
Silicon Carbide Substrate ◽  
Gate Edge

Abstract The influence of double deck T-gate on LG=0.2 μm AlN/GaN/AlGaN HEMT is analysed in this paper. The T-gate supported with Silicon Nitride provides a tremendous mechanical reliability. It drops off the crest electric-field at gate edges and postponing the breakdown voltage of a device. A 0.2-μm double deck T-gate HEMT on Silicon Carbide substrate offer fMAX of 107 Giga Hertz, fT of 60 Giga Hertz and the breakdown voltage of 136 Volts. Furthermore, it produces the maximum-transconductance and drain-current of 0.187 Siemens/mm and 0.41 Ampere/mm respectively. In addition, the lateral electric-field noticed at gate-edge shows 2.1×106 Volts/cm. Besides, the double deck T-gate AlN/GaN HEMT achieves a 45 % increment in breakdown voltage compared to traditional GaN-HEMT device. Moreover, it reveals a remarkable Johnson figure-of-merit of 7.9 Tera Hertz Volt. Therefore, the double deck T-gate on AlN/GaN/AlGaN HEMT is the superlative device for 60 GHz V-band satellite application.

Thermal breakdown in high voltage direct current cable insulations due to space charges

2018 ◽  
Vol 37 (5) ◽  
pp. 1689-1697 ◽  
Author(s):  
Christoph Jörgens ◽  
Markus Clemens
Keyword(s):  
Electric Field ◽  
Breakdown Voltage ◽  
High Voltage ◽  
Direct Current ◽  
Aging Effect ◽  
Radial Symmetry ◽  
Thermal Breakdown ◽  
Content Type ◽  
High Voltage Direct Current ◽  
Space Charges

Purpose In high voltage direct current (HVDC), power cables heat is generated inside the conductor and the insulation during operation. A higher amount of the generated heat in comparison to the dissipated one, results in a possible thermal breakdown. The accumulation of space charges inside the insulation results in an electric field that contributes to the geometric electric field, which comes from the applied voltage. The total electric field decreases in the vicinity of the conductor, while it increases near the sheath, causing a possible change of the breakdown voltage. Design/methodology/approach Here, the thermal breakdown is studied, also incorporating the presence of space charges. For a developed electro-thermal HVDC cable model, at different temperatures, the breakdown voltage is computed through numerical simulations. Findings The simulation results show a dependence of the breakdown voltage on the temperature at the location of the sheath. The results also show only limited influence of the space charges on the breakdown voltage. Research limitations/implications The study is restricted to one-dimensional problems, using radial symmetry of the cable, and does not include any aging or long-term effect of space charges. Such aging effect can locally increase the electric field, resulting in a reduced breakdown voltage. Originality/value A comparison of the breakdown voltage with and without space charges is novel. The chosen approach allows for the first time to assess the influence of space charges and field inversion on the thermal breakdown.

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