Hot-Electron Effects in AlGaN/GaN HEMTs Under Semi-ON DC Stress

Over the last decade, gallium nitride has emerged as an excellent material for the fabrication of power devices. Among the semiconductors for which power devices are already available on the market, GaN has the widest energy gap, the largest critical field, the highest saturation velocity, thus representing an excellent material for the fabrication of high speed/high voltage components.The presence of spontaneous and piezoelectric polarization allows to create a 2-dimensional electron gas, with high mobility and large channel density, in absence of any doping, thanks to the use of AlGaN/GaN heterostructures. This contributes to minimize resistive losses; at the same time, for GaN transistors switching losses are very low, thanks to the small parasitic capacitances and switching charges. Device scaling and monolithic integration enable high frequency operation, with consequent advantages in terms of miniaturization.For high power/high voltage operation, vertical device architectures are being proposed and investigated, and 3-dimensional structuresfin-shaped, trench-structured, nanowire-basedare demonstrating a great potential. Contrary to silicon, GaN is a relatively young material: trapping and degradation processes must be understood and described in detail, with the aim of optimizing device stability and reliability. This tutorial paper describes the physics, technology and reliability of GaN-based power devices: in the first part of the article, starting from a discussion of the main properties of the material, the characteristics of lateral and vertical GaN transistors are discussed in detail, to provide guidance in this complex and interesting field. The second part of the paper focuses on trapping and reliability aspects: the physical origin of traps in GaN, and the main degradation mechanisms are discussed in detail. The wide set of referenced papers and the insight on the most relevant aspects gives the reader a comprehensive overview on present and next-generation GaN electronics. IntroductionOver the past decade, gallium nitride has emerged as an excellent material for the fabrication of power semiconductor devices. Thanks to the unique properties of GaN, diodes and transistors based on this material have excellent performance, compared to their silicon counterparts, and are expected to find wide application in the next-generation power converters. Owing to the flexibility and the energy efficiency of GaN-based power converters, the interest towards this technology is rapidly growing: the aim of this tutorial is to review the most relevant physical properties, the operating principles, the fabrication parameters, and the stability/reliability issues of GaN-based power transistors. For introductory purposes, we start summarizing the physical reasons why GaN transistors achieve a much better performance than the corresponding silicon devices, to help the reader understanding the unique advantages of this technology.The properties of GaN devices allow the fabrication of high-efficiency (near or above 99 %)...

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“…The additional dynamic-Ron detected in semi-on state was ascribed to hot-electron trapping at the passivation/AlGaN interface [565].…”

Section: Semi-on-statementioning

confidence: 93%

GaN-based power devices: Physics, reliability, and perspectives

Meneghini

Santi

Abid

et al. 2021

Journal of Applied Physics

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294

126

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“…In our previous works we demonstrated that the hot-electrons injection mainly involves surface trapping 27 . To summarize our results, we observed that the trapping kinetics follows a logarithmic trend, thus reconducting it to an inhibition effect originated from the Coulombic repulsion between a filled trap and a free electron injected to the surface 28 .…”

Section: Experimental Trap-state Mapping On Gan-based Transistorsmentioning

confidence: 95%

Trap-state mapping to model GaN transistors dynamic performance

Modolo

Santi

Minetto

et al. 2022

Sci Rep

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Trapping phenomena degrade the dynamic performance of wide-bandgap transistors. However, the identification of the related traps is challenging, especially in presence of non-ideal defects. In this paper, we propose a novel methodology (trap-state mapping) to extract trap parameters, based on the mathematical study of stretched exponential recovery kinetics. To demonstrate the effectiveness of the approach, we use it to identify the properties of traps in AlGaN/GaN transistors, submitted to hot-electron stress. After describing the mathematical framework, we demonstrate that the proposed methodology can univocally describe the properties of the distribution of trap states. In addition, to prove the validity and the usefulness of the model, the trap properties extracted mathematically are used as input for TCAD simulations. The results obtained by TCAD closely match the experimental transient curves, thus confirming the accuracy of the trap-state mapping procedure. This methodology can be adopted also on other technologies, thus constituting a universal approach for the analysis of multiexponential trapping kinetics.

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“…Since the review [62] published in 2019, many recent studies on SP-HEMTs and HD-GITs have reported consistently new understandings on the D-R DS,ON issue: a) the D-R DS,ON is more strongly affected by the hard turn-ON process than the OFFstate [66]- [69]; b) the OFF-state stress primarily induces electron trapping in the buffer, while the hard turn-ON stress induces electron trapping in both the buffer and the interface between AlGaN and passivation layer [67], [70]. Some studies report the interface/surface trapping to dominate in the hard turn-ON process while observing the impact of buffer region design [66], [67] and drain field plate design [71] on surface trapping. Studies have also shown that the traps relevant to the hard turn-ON process possess a broadly-distributed but relatively shallow energy level [72], [73].…”

Section: A Dynamic On-resistancementioning

confidence: 99%

Stability, Reliability, and Robustness of GaN Power Devices: A Review

Kozak

Zhang

Porter

et al. 2023

IEEE Trans. Power Electron.

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Gallium nitride (GaN) devices are revolutionarily advancing the efficiency, frequency, and form factor of power electronics. However, the material composition, architecture and physics of many GaN devices are significantly different from silicon and silicon carbide devices. These distinctions result in many unique stability, reliability and robustness issues facing GaN power devices. This paper reviews the current understanding of these issues, particularly those related to dynamic switching, and their impacts on system performance. Instead of delving into reliability physics, this paper intends to provide power electronics engineers the necessary information for deploying GaN devices in existing and emerging applications, as well as provide references for the qualification evaluations of GaN power devices. The issues covered in this paper include the dynamic instability of device parameters (e.g., on-resistance, threshold voltage, output capacitance), the device robustness in avalanche, overvoltage and short-circuit conditions, the device's switching reliability and lifetime, as well as the device's ruggedness under radiation and extreme (cryogenic and elevated) temperatures. Knowledge gaps and immediate research opportunities in the relevant fields are also discussed. 1

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Hot-Electron Effects in AlGaN/GaN HEMTs Under Semi-ON DC Stress

Cited by 49 publications

References 18 publications

GaN-based power devices: Physics, reliability, and perspectives

GaN-based power devices: Physics, reliability, and perspectives

Trap-state mapping to model GaN transistors dynamic performance

Stability, Reliability, and Robustness of GaN Power Devices: A Review

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