Download or read book Degradation of GaN High Electron Mobility Transistors Under High power and High temperature Stress written by Yufei Wu (S.M.) and published by . This book was released on 2014 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: GaN HEMTs (High Electron Mobility Transistors) are promising candidates for high power and high frequency applications but their reliability needs to be established before their wide deployment can be realized. In this thesis, degradation mechanisms of GaN HEMTs under high-power and high-temperature stress have been studied. A novel technique to extract activation energy of degradation rate from measurements on a single device has been proposed. High-power and high-temperature stress has revealed two sequential degradation mechanisms where the gate current degrades first and saturates only after which the drain current shows significant degradation. A study of the semiconductor surface of delaminated degraded devices shows formation of grooves and pits at the gate edge on the drain side. Electrical degradation is shown to directly correlate with structural degradation. Also, higher junction temperature is shown to results in more severe structural degradation.

Download or read book Degradation Mechanisms of GaN HEMTs written by Jungwoo Joh and published by . This book was released on 2007 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) From a set of our experiments, we have hypothesized that the main mechanism behind device degradation is defect formation through the inverse piezoelectric effect and subsequent electron trapping. Unlike current conventional wisdom, hot electrons are less likely to be the direct cause of electrical degradation in the devices that we have studied. Our studies suggest a number of possibilities to improve the electrical reliability of GaN HEMTs.

Download or read book GaN High Electron Mobility Transistor Degradation written by and published by . This book was released on 2012 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electrical and Electronic Devices Circuits and Materials written by Suman Lata Tripathi and published by John Wiley & Sons. This book was released on 2021-03-24 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: The increasing demand for electronic devices for private and industrial purposes lead designers and researchers to explore new electronic devices and circuits that can perform several tasks efficiently with low IC area and low power consumption. In addition, the increasing demand for portable devices intensifies the call from industry to design sensor elements, an efficient storage cell, and large capacity memory elements. Several industry-related issues have also forced a redesign of basic electronic components for certain specific applications. The researchers, designers, and students working in the area of electronic devices, circuits, and materials sometimesneed standard examples with certain specifications. This breakthrough work presents this knowledge of standard electronic device and circuit design analysis, including advanced technologies and materials. This outstanding new volume presents the basic concepts and fundamentals behind devices, circuits, and systems. It is a valuable reference for the veteran engineer and a learning tool for the student, the practicing engineer, or an engineer from another field crossing over into electrical engineering. It is a must-have for any library.

Download or read book Reliability and Degradation Mechanisms of GaN High Electron Mobility Transistors with Short Gate Length written by Tobias Kemmer and published by . This book was released on 2021* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics of Electrical Degradation in GaN High Electron Mobility Transistors written by Jungwoo Joh and published by . This book was released on 2009 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) When the elastic energy in the crystal exceeds a critical value, crystallographic defects are formed. These defects trap electrons and reduce drain current as well as provide leakage paths and increase gate current. We theoretically validate the plausibility of this hypothesis and provide a model for the critical voltage that agrees with experimental observations. Unlike conventional wisdom, hot electrons do not appear to be the direct cause of electrical degradation in the devices that we study. Our studies suggest several possibilities to improving the electrical reliability of GaN HEMTs.

Download or read book Handbook for III V High Electron Mobility Transistor Technologies written by D. Nirmal and published by CRC Press. This book was released on 2019-05-14 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focusses on III-V high electron mobility transistors (HEMTs) including basic physics, material used, fabrications details, modeling, simulation, and other important aspects. It initiates by describing principle of operation, material systems and material technologies followed by description of the structure, I-V characteristics, modeling of DC and RF parameters of AlGaN/GaN HEMTs. The book also provides information about source/drain engineering, gate engineering and channel engineering techniques used to improve the DC-RF and breakdown performance of HEMTs. Finally, the book also highlights the importance of metal oxide semiconductor high electron mobility transistors (MOS-HEMT). Key Features Combines III-As/P/N HEMTs with reliability and current status in single volume Includes AC/DC modelling and (sub)millimeter wave devices with reliability analysis Covers all theoretical and experimental aspects of HEMTs Discusses AlGaN/GaN transistors Presents DC, RF and breakdown characteristics of HEMTs on various material systems using graphs and plots

Download or read book Handbook for III V High Electron Mobility Transistor Technologies written by D. Nirmal and published by CRC Press. This book was released on 2019-05-14 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focusses on III-V high electron mobility transistors (HEMTs) including basic physics, material used, fabrications details, modeling, simulation, and other important aspects. It initiates by describing principle of operation, material systems and material technologies followed by description of the structure, I-V characteristics, modeling of DC and RF parameters of AlGaN/GaN HEMTs. The book also provides information about source/drain engineering, gate engineering and channel engineering techniques used to improve the DC-RF and breakdown performance of HEMTs. Finally, the book also highlights the importance of metal oxide semiconductor high electron mobility transistors (MOS-HEMT). Key Features Combines III-As/P/N HEMTs with reliability and current status in single volume Includes AC/DC modelling and (sub)millimeter wave devices with reliability analysis Covers all theoretical and experimental aspects of HEMTs Discusses AlGaN/GaN transistors Presents DC, RF and breakdown characteristics of HEMTs on various material systems using graphs and plots

Download or read book Evaluation of Degradation in GaN High Electron Mobility Transistors Due to the Inverse Piezoelectric Effect written by Deepthi Nagulapally and published by . This book was released on 2014 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Power GaN Devices written by Matteo Meneghini and published by Springer. This book was released on 2016-09-08 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the first comprehensive overview of the properties and fabrication methods of GaN-based power transistors, with contributions from the most active research groups in the field. It describes how gallium nitride has emerged as an excellent material for the fabrication of power transistors; thanks to the high energy gap, high breakdown field, and saturation velocity of GaN, these devices can reach breakdown voltages beyond the kV range, and very high switching frequencies, thus being suitable for application in power conversion systems. Based on GaN, switching-mode power converters with efficiency in excess of 99 % have been already demonstrated, thus clearing the way for massive adoption of GaN transistors in the power conversion market. This is expected to have important advantages at both the environmental and economic level, since power conversion losses account for 10 % of global electricity consumption. The first part of the book describes the properties and advantages of gallium nitride compared to conventional semiconductor materials. The second part of the book describes the techniques used for device fabrication, and the methods for GaN-on-Silicon mass production. Specific attention is paid to the three most advanced device structures: lateral transistors, vertical power devices, and nanowire-based HEMTs. Other relevant topics covered by the book are the strategies for normally-off operation, and the problems related to device reliability. The last chapter reviews the switching characteristics of GaN HEMTs based on a systems level approach. This book is a unique reference for people working in the materials, device and power electronics fields; it provides interdisciplinary information on material growth, device fabrication, reliability issues and circuit-level switching investigation.

Download or read book Reliability of GaN High Electron Mobility Transistors on Silicon Substrates written by Sefa Demirtas and published by . This book was released on 2009 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: GaN High Electron Mobility Transistors are promising devices for high power and high frequency applications such as cellular base stations, radar and wireless network systems, due to the high bandgap and high breakdown field of GaN. However, their reliability is the main hindrance to the deployment of these transistors in a wide scale. In this study, we have investigated the reliability of GaN HEMTs grown on Si substrates. The large lattice and thermal mismatch between GaN and Si adds an additional reliability concern as compared to conventional substrates such as SiC and sapphire. We have performed systematic electrical stress experiments to understand the physics of degradation in these devices. Relevant device parameters are recorded continuously during these stress tests by a benign characterization suite. We conclude from these experiments that high voltage stress conditions are more effective in degrading the device than high current conditions. High voltage stress is found to impact the device in two different ways. The first is increased trapping in the large number of traps in the highly mismatched device structure even before any stress. The second is through the converse piezoelectric effect discussed by Joh et al. for GaN-on-SiC devices. We also have found evidence that these two mechanisms are connected. We have used UV illumination to enhance detrapping and shown that trapped electrons screen the electric field in the device and increase the critical voltage at which gate current degrades.

Download or read book Short Circuit Capability and Degradation Mechanism Analysis of E mode GaN HEMT written by Xiao Li and published by . This book was released on 2017 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gallium Nitride High Electron Mobility Transistor (GaN HEMT) has become one of the most attractive power transistors in recent years due to its superior electrical and thermal performance. While GaN devices have been used in more and more applications, short circuit capability of GaN HEMT and the method to qualify its reliability still worth discussion. This report presents the short circuit behavior of discrete 650 V/ 30 A large current rating Enhancement-mode (E-mode) GaN HEMT devices under single and repetitive short circuit operations. Firstly, structure and characteristics of GaN HEMT are introduced. Both cross-section structure of the lateral power transistor and gate structure of normally-off GaN HEMT are presented. Next, detailed test platform design is presented. The platform is established based on hard switching fault (HSF) circuit, and the turn-off transient is evaluated, which proved that soft turn-off is required for GaN HEMT short circuit tests. Besides, a system level thermal model based on FEA simulation and Cauer thermal network is established to have an accurate prediction of devices junction temperature. Then, short circuit roughness has been explored through designed tests, from these tests, maximum short circuit time, short circuit critical energy, as well as short circuit failure behavior and the mechanism is explored and analyzed. For the repetitive short circuit degradation tests, a series of experimental tests are carried out to determine the number of short circuit operations the devices can support before obvious degradation happens under different dissipated energies. More importantly, device static characteristics are explored and monitored during the degradation tests, and the characteristics shifting has been investigated and acts as the indicators of devices degradation. For different kinds of test, including failure condition, test waveforms are presented together with detailed analysis and mechanism discussion.

Download or read book III Nitride Electronic Devices written by Rongming Chu and published by Academic Press. This book was released on 2019-10 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: III-Nitride Electronic Devices, Volume 102, emphasizes two major technical areas advanced by this technology: radio frequency (RF) and power electronics applications. The range of topics covered by this book provides a basic understanding of materials, devices, circuits and applications while showing the future directions of this technology. Specific chapters cover Electronic properties of III-nitride materials and basics of III-nitride HEMT, Epitaxial growth of III-nitride electronic devices, III-nitride microwave power transistors, III-nitride millimeter wave transistors, III-nitride lateral transistor power switch, III-nitride vertical devices, Physics-Based Modeling, Thermal management in III-nitride HEMT, RF/Microwave applications of III-nitride transistor/wireless power transfer, and more. Presents a complete review of III-Nitride electronic devices, from fundamental physics, to applications in two key technical areas - RF and power electronics Outlines fundamentals, reviews state-of-the-art circuits and applications, and introduces current and emerging technologies Written by a panel of academic and industry experts in each field

Download or read book GaN Based HEMTs for High Voltage Operation Design Technology and Characterization written by Eldad Bahat-Treidel and published by Cuvillier Verlag. This book was released on 2012-06-08 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gallium nitride (GaN)-based High Electron Mobility Transistors (HEMTs) for high voltage, high power switching and regulating for space applications are studied in this work. Efficient power switching is associated with operation in high OFF-state blocking voltage while keeping the ON-state resistance, the dynamic dispersion and leakage currents as low as possible. The potential of such devices to operate at high voltages is limited by a chain of factors such as subthreshold leakages and the device geometry. Blocking voltage enhancement is a complicated problem that requires parallel methods for solution; epitaxial layers design, device structural and geometry design, and suitable semiconductor manufacturing technique. In this work physical-based device simulation as an engineering tool was developed. An overview on GaN-based HEMTs physical based device simulation using Silvaco-“ATLAS” is given. The simulation is utilized to analyze, give insight to the modes of operation of the device and for design and evaluation of innovative concepts. Physical-based models that describe the properties of the semiconductor material are introduced. A detailed description of the specific AlGaN/GaN HEMT structure definition and geometries are given along with the complex fine meshing requirements. Nitride-semiconductor specific material properties and their physical models are reviewed focusing on the energetic band structure, epitaxial strain tensor calculation in wurtzite materials and build-in polarization models. Special attention for thermal conductivity, carriers’ mobility and Schottky-gate-reverse-bias-tunneling is paid. Empirical parameters matching and adjustment of models parameters to match the experimental device measured results are discussed. An enhancement of breakdown voltage in AlxGa1-xN/GaN HEMT devices by increasing the electron confinement in the transistor channel using a low Al content AlyGa1-yN back-barrier layer structure is systematically studied. It is shown that the reduced sub-threshold drain-leakage current through the buffer layer postpones the punch-through and therefore shifts the breakdown of the device to higher voltages. It is also shown that the punch-through voltage (VPT) scales up with the device dimensions (gate to drain separation). An optimized electron confinement results both, in a scaling of breakdown voltage with device geometry and a significantly reduced sub-threshold drain and gate leakage currents. These beneficial properties are pronounced even further if gate recess technology is applied for device fabrication. For the systematic study a large variations of back-barrier epitaxial structures were grown on sapphire, n-type 4H-SiC and semi-insulating 4H-SiC substrates. The devices with 5 μm gate-drain separation grown on n-SiC owning Al0.05Ga0.95N and Al0.10Ga0.90N back-barrier exhibit 304 V and 0.43 m × cm2 and 342 V and 0.41 m × cm2 respectively. To investigate the impact of AlyGa1-yN back-barrier on the device properties the devices were characterized in DC along with microwave mode and robustness DC-step-stress test. Physical-based device simulations give insight in the respective electronic mechanisms and to the punch-through process that leads to device breakdown. Systematic study of GaN-based HEMT devices with insulating carbon-doped GaN back-barrier for high voltage operation is also presented. Suppression of the OFF-state sub-threshold drain leakage-currents enables breakdown voltage enhancement over 1000 V with low ON-state resistance. The devices with 5 μm gate-drain separation on SI-SiC and 7 μm gate-drain separation on n-SiC exhibit 938 V and 0.39 m × cm2 and 942 V and 0.39 m × cm2 respectively. Power device figure of merit of ~2.3 × 109 V2/-cm2 was calculated for these devices. The impacts of variations of carbon doping concentration, GaN channel thickness and substrates are evaluated. Trade-off considerations in ON-state resistance and of current collapse are addressed. A novel GaN-based HEMTs with innovative planar Multiple-Grating-Field-Plates (MGFPs) for high voltage operation are described. A synergy effect with additional electron channel confinement by using a heterojunction AlGaN back-barrier is demonstrated. Suppression of the OFF-state sub-threshold gate and drain leakage-currents enables breakdown voltage enhancement over 700 V and low ON-state resistance of 0.68 m × cm2. Such devices have a minor trade-off in ON-state resistance, lag factor, maximum oscillation frequency and cut-off frequency. Systematic study of the MGFP design and the effect of Al composition in the back-barrier are described. Physics-based device simulation results give insight into electric field distribution and charge carrier concentration depending on field-plate design. The GaN superior material breakdown strength properties are not always a guarantee for high voltage devices. In addition to superior epitaxial growth design and optimization for high voltage operation the device geometrical layout design and the device manufacturing process design and parameters optimization are important criteria for breakdown voltage enhancement. Smart layout prevent immature breakdown due to lateral proximity of highly biased interconnects. Optimization of inter device isolation designed for high voltage prevents substantial subthreshold leakage. An example for high voltage test device layout design and an example for critical inter-device insulation manufacturing process optimization are presented. While major efforts are being made to improve the forward blocking performance, devices with reverse blocking capability are also desired in a number of applications. A novel GaN-based HEMT with reverse blocking capability for Class-S switch-mode amplifiers is introduced. The high voltage protection is achieved by introducing an integrated recessed Schottky contact as a drain electrode. Results from our Schottky-drain HEMT demonstrate an excellent reverse blocking with minor trade-off in the ON-state resistance for the complete device. The excellent quality of the forward diode characteristics indicates high robustness of the recess process. The reverse blocking capability of the diode is better than –110 V. Physical-based device simulations give insight in the respective electronic mechanisms. Zusammenfassung In dieser Arbeit wurden Galliumnitrid (GaN)-basierte Hochspannungs-HEMTs (High Electron Mobility Transistor) für Hochleistungsschalt- und Regelanwendungen in der Raumfahrt untersucht. Effizientes Leistungsschalten erfordert einen Betrieb bei hohen Sperrspannungen gepaart mit niedrigem Einschaltwiderstand, geringer dynamischer Dispersion und minimalen Leckströmen. Dabei wird das aus dem Halbleitermaterial herrührende Potential für extrem spannungsfeste Transistoren aufgrund mehrerer Faktoren aus dem lateralen und dem vertikalen Bauelementedesign oft nicht erreicht. Physikalisch-basierte Simulationswerkzeuge für die Bauelemente wurden daher entwickelt. Die damit durchgeführte Analyse der unterschiedlichen Transistorbetriebszustände ermöglichte das Entwickeln innovativer Bauelementdesignkonzepte. Das Erhöhen der Bauelementsperrspannung erfordert parallele und ineinandergreifende Lösungsansätze für die Epitaxieschichten, das strukturelle und das geometrische Design und für die Prozessierungstechnologie. Neuartige Bauelementstrukturen mit einer rückseitigen Kanalbarriere (back-barrier) aus AlGaN oder Kohlenstoff-dotierem GaN in Kombination mit neuartigen geometrischen Strukturen wie den Mehrfachgitterfeldplatten (MGFP, Multiple-Grating-Field-Plate) wurden untersucht. Die elektrische Gleichspannungscharakterisierung zeigte dabei eine signifikante Verringerung der Leckströme im gesperrten Zustand. Dies resultierte bei nach wie vor sehr kleinem Einschaltwiderstand in einer Durchbruchspannungserhöhung um das etwa Zehnfache auf über 1000 V. Vorzeitige Spannungsüberschläge aufgrund von Feldstärkenspitzen an Verbindungsmetallisierungen werden durch ein geschickt gestaltetes Bauelementlayout verhindert. Eine Optimierung der Halbleiterisolierung zwischen den aktiven Strukturen führte auch im kV-Bereich zu vernachlässigbaren Leckströme. Während das Hauptaugenmerk der Arbeit auf der Erhöhung der Spannungsfestigkeit im Vorwärtsbetrieb des Transistors lag, ist für einige Anwendung auch ein rückwärtiges Sperren erwünscht. Für Schaltverstärker im S-Klassenbetrieb wurde ein neuartiger GaN-HEMT entwickelt, dessen rückwärtiges Sperrverhalten durch einen tiefgelegten Schottkykontakt als Drainelektrode hervorgerufen wird. Eine derartige Struktur ergab eine rückwärtige Spannungsfestigkeit von über 110 V.

Download or read book AlGaN GaN HEMTs Reliability Degradation Modes and Analysis written by Ponky Ivo and published by Cuvillier. This book was released on 2012-10-25 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: AlGaN/GaN HEMTs reliability and stability issues were investigated in dependence on epitaxial design and process modification. DC-Step-Stress-Tests have been performed on wafers as a fast device robustness screening method. As a criterion of robustness they deliver a critical source-drain voltage for the onset of degradation. Several degradation modes were observed which depend on epi design, epi quality and process technology. Electrical and optical characterizations together with electric field simulations were performed to get insight into respective degradation modes. It has been found that AlGaN/GaN HEMT devices with GaN cap show higher critical source-drain voltages as compared to non-capped devices. Devices with low Al concentration in the AlGaN barrier layer also show higher critical source-drain voltages. Superior stability and robustness performance have been achieved from devices with AlGaN backbarrier epi design grown on n-type SiC substrate. For the onset on any degradation modes the presence of high electrical fields is most decisive for ON- and OFF-state operation conditions. Therefore careful epi design to reduce high electric field is mandatory. It is also shown that epi buffer quality and growth process have a great impact on device robustness. Defects such as point defects and dislocations are assumed to be created initially during stressing and accumulated to larger defect clusters during device stressing. Electroluminescence (EL) measurements were performed to detect early degradation. Extended localized defects are resulting as bright spots at OFF-state conditions in conjunction with a gate leakage increase.

Download or read book Degradation Study of AIGaN GaN High Electron Mobility Transistors Through Electro thermo mechanical Calculations and Thermo reflectance Measurements written by Feng Gao (Ph. D.) and published by . This book was released on 2010 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the last few years, AIGaN/GaN high electron mobility transistors (HEMTs) have been intensively studied for high frequency high power applications. In spite of this great interest, device reliability is still an important challenge for the wide deployment of AIGaN/GaN HEMT technology. To fully understand reliability in these devices, it is necessary to consider the electrical, mechanical and thermal properties of the operating AIGaN/GaN transistors. Since AIGaN and GaN are both piezoelectric materials, the coupling among electric field, lattice heating and mechanical characteristics gives rise to large changes in strain field and elastic energy density in the transistors under the pinch-off conditions. Most previous work have studied the inverse piezoelectric effect on device degradations, however, quantitative analysis of this failure mechanism is still needed. In this thesis, we have developed the first fully-coupled electro-thermo-mechanical simulation of AIGaN/GaN HEMTs to study the correlation between the critical voltages of the gate current degradation and the lattice temperature distributions of these devices under the reverse-gate-bias reliability testing. In addition, we have compared the numerical results of our simulations with DC measurements and high resolution thermo-reflectance images, obtaining excellent agreement for both of them. Moreover, our studies suggest a covenient and low-cost way to obtain the reliability characteristics of AIGaN/GaN HEMTs by using the thermo-reflectance measurements of the lattice temperature distributions for those devices.

Download or read book Reliability of W Band InAIN GaN High Electron Mobility Transistors written by Yufei Wu (Ph. D.) and published by . This book was released on 2017 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: AlGaN/GaN High Electron Mobility Transistors (HEMTs) have enjoyed tremendous market growth in RF power amplifiers over the past decades. In the quest for enhancing the operating frequency of GaN HEMTs, there has been a great effort to scale down the gate length. Maintaining acceptable short-channel effects requires shrinking the barrier thickness at the same time. However, a limitation exists since there is a minimum barrier thickness that is needed to obtain a sufficiently high two-dimensional electron gas density. One possible solution to this problem is the use of a new barrier material, i.e., InAlN. Due to its high spontaneous polarization, if InAlN is used as a barrier material in GaN HEMTs, a much smaller layer thickness is required compared with conventional HEMTs. This enables further barrier thickness scaling and therefore gate length scaling and a higher frequency response. However, as a relatively new structure, reliability studies of InAlN/GaN HEMTs are still lacking. Solid reliability is essential before the wide commercial deployment of this new technology. This thesis investigates the most relevant degradation mechanisms under important stress regimes, aiming at building a comprehensive understanding of InAIN/GaN HEMT reliability. Through investigating various voltage, current, and temperature stress levels, we have identified one recoverable degradation mechanism as well as three permanent degradation mechanisms. Under high drain voltage, hot-electron trapping results in temporary drain current decrease and drain resistance increase. In addition, under high drain voltage but relatively low drain current level, permanent negative threshold voltage shift and drain current increase have been observed. We attribute the phenomena to dehydrogenation of pre-existing defects in GaN channel by hot electrons. Under high positive gate bias, defect generation in the AIN interlayer due to high electric field across AIN has proven to be responsible for the observed gate leakage current increase. Also, under high-power stress conditions, positive threshold voltage shift and maximum drain current decrease have been consistently observed. We verified through both thermal stress experiments and Transmission Electron Microscopy (TEM) analysis that Schottky gate sinking is the cause. This work provides fundamental understanding of potential reliability concerns in InAlN/GaN HEMTs and is essential in accelerating the future commercialization of this promising technology.