Characterization and Modeling of the Impact of the Substrate Potential in the Dynamic and Static Behavior of Power GaN-on-Si HEMTs

The development of gallium nitride (GaN) on silicon (Si) substrates is a critical technology for potential low cost power electronics. These devices can accommodate faster switching speeds, hotter temperatures, and high voltages needed for power electronics applications. However, the lattice mismatch and difference in crystal structure between 111 Si and c-axis hexagonal GaN requires the use of buffer layers in order to grow device quality epitaxial layers. For lateral high electron mobility transistors, these interfacial layers act as a potential source of increased thermal boundary resistance (TBR) which impedes heat flow out of the GaN on Si devices. In addition, these interfacial layers impact the growth and residual stress in the GaN epitaxial layer which can play a role in device reliability. In this work we use optical methods to experimentally measure a relatively low TBR for GaN on Si with an intermediate buffer layer to be 3.8 ± 0.4 m2K/GW. The effective TBR of a material stack that encompasses GaN on Si with a superlattice (SL) buffer is also measured, and is found to be 107 ± 1 m2K/GW. In addition the residual state of strain in the GaN layer is measured for both samples, and is found to vary significantly between them. Thermal conductivity of a 0.8μm GaN layer on AlN buffer is determined to be 126 ± 25 W/m-K, while a 0.84 μm GaN layer with C-doping on a SL structure is determined to be 112 ± 29 W/m-K.

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

Micromachines ◽

10.3390/mi12040445 ◽

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.

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GaN-on-Si lateral power devices with symmetric vertical leakage: The impact of floating substrate

2018 IEEE 30th International Symposium on Power Semiconductor Devices and ICs (ISPSD) ◽

10.1109/ispsd.2018.8393612 ◽

2018 ◽

Cited By ~ 4

Author(s):

Hanyuan Zhang ◽

Shu Yang ◽

Kuang Sheng

Keyword(s):

Power Devices ◽

Vertical Leakage ◽

Gan On Si ◽

The Impact

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Active Control of Stiffness of Tensegrity Plate-like Structures Built with Simplex Modules

Materials ◽

10.3390/ma14247888 ◽

2021 ◽

Vol 14 (24) ◽

pp. 7888

Author(s):

Paulina Obara ◽

Justyna Tomasik

Keyword(s):

Stress State ◽

Linear Model ◽

Active Control ◽

Static Behavior ◽

Deployable Structures ◽

Structural Concept ◽

Non Linear ◽

Stress States ◽

Support Conditions ◽

The Impact

The aim of this study is to prove that it is possible to control the static behavior of tensegrity plate-like structures. This possibility is very important, particularly in the case of deployable structures. Here, we analyze the impact the support conditions of the structure have on the existence of specific characteristics, such as self-stress states and infinitesimal mechanisms, and, consequently, on the active control. Plates built with Simplex modules are considered. Firstly, the presence of the specific characteristics is examined, and a classification is carried out. Next, the influence of the level of self-stress state on the behavior of structures is analyzed. A geometrically non-linear model, implemented in an original program, written in the Mathematica environment, is used. The results confirm the feasibility of the active control of stiffness of tensegrity plate-like structures characterized by the presence of infinitesimal mechanisms. In the case when mechanisms do not exist, structures are insensitive to the initial prestress level. It is possible to control the occurrence of mechanisms by changing the support conditions of the structure. Based on the obtained results, tensegrity is very promising structural concept, applicable in many areas, when conventional solutions are insufficient.

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On the impact of substrate electron injection on dynamic Ron in GaN-on-Si HEMTs

Microelectronics Reliability ◽

10.1016/j.microrel.2018.07.102 ◽

2018 ◽

Vol 88-90 ◽

pp. 610-614 ◽

Cited By ~ 2

Author(s):

Dario Pagnano ◽

Giorgia Longobardi ◽

Florin Udrea ◽

Jinming Sun ◽

Mohamed Imam ◽

...

Keyword(s):

Electron Injection ◽

Gan On Si ◽

The Impact

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Experimental Characterization and Static Modeling of McKibben Actuators

Aerospace ◽

10.1115/imece2006-15390 ◽

2006 ◽

Cited By ~ 4

Author(s):

Curt S. Kothera ◽

Mamta Jangid ◽

Jayant Sirohi ◽

Norman M. Wereley

Keyword(s):

Energy Storage ◽

Elastic Energy ◽

Weight Ratio ◽

Rubber Tube ◽

Force Output ◽

Static Behavior ◽

Series Of Experiments ◽

Mckibben Actuators ◽

Improved Model ◽

The Impact

McKibben actuators are pneumatic actuators with very high force to weight ratio. Their ability to match the behavior of biological muscles better than many other actuators has motivated much research into characterization and modeling of these actuators. The purpose of this paper is to experimentally characterize the behavior of McKibben artificial muscles with basic geometric parameters and present a model that is able to predict the static behavior correctly in terms of blocked force and free displacement. A series of experiments aimed at understanding the static behavior of the actuators was conducted. The results for three different lengths (4, 6, 8 in), three diameters (1/8, 1/4, 3/8 in) and two wall thicknesses (1/32 and 1/16 in) at pressures ranging from 10 psi to 60 psi show the expected trends (for example, block force increasing with diameter) as predicted by models presented in the literature. However, these models do not accurately predict static behavior. Corrections to the Gaylord equation are explored in order to obtain a more accurate model. Consideration of elastic energy storage in the rubber tube has been shown to significantly improve the models. Apart from this, the effect of non-cylindrical tips and elastic energy storage in the braid are also considered. To increase model accuracy, another set of experiments was used to characterize the elasticity of the rubber tubes and fibers of the braid. The improved model is able to predict static behavior correctly. Incorporating, various corrections, a model is presented that is more accurate in predicting the static behavior. Finally, in order to possibly obtain larger force output from the McKibben actuators, a series of experiments were performed to study the impact of an applied pre-strain. The results presented show large increases in blocked force with pre-strain. For the largest diameter actuator of 6 inch length, the blocked force at 12% pre-strain is as high as 270 N, while the amplification is higher at lower pressures. The model is tested to predict the pre-strain characteristics. A number of factors are identified that may improve the model and incorporate dynamic behavior.

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