Wide Bandgap Sic Gan Power Devices Characterization And Modeling

Compared to traditional silicon (Si) semiconductor material, wide bandgap (WBG) materials like silicon carbide (SiC) and gallium nitride are gradually applied to fabricate power semiconductor devices, which are used in power converters to achieve high power efficiency, high operation temperature and high switching frequency. As those power devices are relatively new, their characterization and modeling are important to better understand their characteristics for better use. This dissertation is mainly focused on those WBG power semiconductor devices characterization, modeling and fast switching currents measurement. In order to measure their static characteristics, a single-pulse method is presented. A SiC diode and a "normally-off" SiC JFET is characterized by this method from ambient temperature to their maximal junction temperature with the maximal power dissipation around kilowatt. Afterwards, in order to determine power device inter-electrode capacitances, a measurement method based on the use of multiple current probes is proposed and validated by measuring inter-electrode capacitances of power devices of different technologies. Behavioral models of a Si diode and the SiC JFET are built by using the results of the above characterization methods, by which the evolution of the inter-electrode capacitances for different operating conditions are included in the models. Power diode models are validated with the measurements, in which the current is measured by a proposed current surface probe.

This book is an authoritative overview of Wide Bandgap (WBG) device characterization providing essential tools to assist the reader in performing both static and dynamic characterization of WBG devices, particularly those based on using silicon carbide (SiC) and gallium nitride (GaN) power semiconductors.

Emerging wide bandgap (WBG) semiconductors hold the potential to advance the global industry in the same way that, more than 50 years ago, the invention of the silicon (Si) chip enabled the modern computer era. SiC- and GaN-based devices are starting to become more commercially available. Smaller, faster, and more efficient than their counterpart Si-based components, these WBG devices also offer greater expected reliability in tougher operating conditions. Furthermore, in this frame, a new class of microelectronic-grade semiconducting materials that have an even larger bandgap than the previously established wide bandgap semiconductors, such as GaN and SiC, have been created, and are thus referred to as “ultra-wide bandgap” materials. These materials, which include AlGaN, AlN, diamond, Ga2O3, and BN, offer theoretically superior properties, including a higher critical breakdown field, higher temperature operation, and potentially higher radiation tolerance. These attributes, in turn, make it possible to use revolutionary new devices for extreme environments, such as high-efficiency power transistors, because of the improved Baliga figure of merit, ultra-high voltage pulsed power switches, high-efficiency UV-LEDs, and electronics. This Special Issue aims to collect high quality research papers, short communications, and review articles that focus on wide bandgap device design, fabrication, and advanced characterization. The Special Issue will also publish selected papers from the 43rd Workshop on Compound Semiconductor Devices and Integrated Circuits, held in France (WOCSDICE 2019), which brings together scientists and engineers working in the area of III–V, and other compound semiconductor devices and integrated circuits. In particular, the following topics are addressed: – GaN- and SiC-based devices for power and optoelectronic applications – Ga2O3 substrate development, and Ga2O3 thin film growth, doping, and devices – AlN-based emerging material and devices – BN epitaxial growth, characterization, and devices

At the heart of modern power electronics converters are power semiconductor switching devices. The emergence of wide bandgap (WBG) semiconductor devices, including silicon carbide and gallium nitride, promises power electronics converters with higher efficiency, smaller size, lighter weight, and lower cost than converters using the established silicon-based devices. However, WBG devices pose new challenges for converter design and require more careful characterization, in particular due to their fast switching speed and more stringent need for protection.

This work presents a comprehensive modeling strategy for advanced large-size AlGaN/GaN HEMTs. A 22-element equivalent circuit with 12 extrinsic elements, including 6 capacitances, serves as small-signal model and as basis for a large-signal model. ANalysis of such capacitances leads to original equations, employed to form capacitance ratios. BAsic assumptions of existing parameter extractions for 22-element equivalent circuits are perfected: A) Required capacitance ratios are evaluated with device's top-view images. B) Influences of field plates and source air-bridges on these ratios are considered. The large-signal model contains a gate charge's non-quasi-static model and a dispersive-IDS model. THe extrinsic-to-intrinsic voltage transformation needed to calculate non-quasi-static parameters from small-signal parameters is improved with a new description for the measurement's boundary bias points. ALl IDS-model parameters, including time constants of charge-trapping and self-heating, are extracted using pulsed-DC IV and IDS-transient measurements, highlighting the modeling strategy's empirical character.

'This book is more suited for researchers already familiar with WBS who are interested in developing new WBG materials and devices since it provides the latest developments in new materials and processes and trends for WBS and UWBS technology.'IEEE Electrical Insulation MagazineWith the dawn of Gallium Oxide (Ga2O₃) and Aluminum Gallium Nitride (AlGaN) electronics and the commercialization of Gallium Nitride (GaN) and Silicon Carbide (SiC) based devices, the field of wide bandgap materials and electronics has never been more vibrant and exciting than it is now. Wide bandgap semiconductors have had a strong presence in the research and development arena for many years. Recently, the increasing demand for high efficiency power electronics and high speed communication electronics, together with the maturity of the synthesis and fabrication of wide bandgap semicon-ductors, has catapulted wide bandgap electronics and optoelectronics into the mainstream.Wide bandgap semiconductors exhibit excellent material properties, which can potentially enable power device operation at higher efficiency, higher temperatures, voltages, and higher switching speeds than current Si technology. This edited volume will serve as a useful reference for researchers in this field — newcomers and experienced alike.This book discusses a broad range of topics including fundamental transport studies, growth of high-quality films, advanced materials characterization, device modeling, high frequency, high voltage electronic devices and optical devices written by the experts in their respective fields. They also span the whole spectrum of wide bandgap materials including AlGaN, Ga2O₃and diamond.

Wide bandgap devices (GaN) are an enabling technology for high frequency and high efficiency power electronics. Especially, the combination of low on-resistance and high breakdown voltages relates to high power-density capabilities of GaN devices and makes them a potential alternative for silicon devices in high power conversion applications. Also, GaN devices are intrinsically very fast with low switching losses due to high saturation velocities and can achieve higher efficiencies in hard switching applications. On the contrary, low inherent capacitance makes them more vulnerable to high dv/dt transitions and can cause undesired circuit level issues such as voltage overshoot, ringing and false turn-on. Any unchecked external parasitic impedances will further exacerbate the device transient behavior and run the risk of device failure under circuit level implementation. Therefore, this thesis work presents a detailed analytical framework to address some of the circuit level challenges associated with GaN. The analytical framework lays a foundation to optimize device safety and performance. The first part of this thesis work deals with mitigation of false turn-on of the synchronous-FET in a half bridge buck converter operated at 1 MHz frequency. The study presents a detail investigation of false turn-on event and proposes its mitigation by modifying the control-FET gate resistance. An analytical circuit model with intrinsic device components and external parasitic parameters has been considered to develop a relationship between control-FET gate resistance and false turn-on induced voltage of the synchronous-FET. The results of the analytical method proposed in this study show good agreement with the experimental results. The model can then be used to predict false turn-on at varying values of high-side gate resistance. The second part of this thesis focuses on development of an improved model to predict voltage overshoot in normally off GaN devices. As the GaN device requires lower gate bias to fully turn-on when compared to its counterpart (Si), there is a narrow margin between recommended (5V) and max gate voltage rating (6V). Any voltage spike beyond the maximum gate voltage could cause device breakdown and catastrophic failure. Therefore, to avoid such failures and safeguard the GaN device, proper prediction methodologies are required. In this study a higher order (fourth order) analytical method is developed that allows for the calculation of gate resistances necessary for a desired amount of overshoot. The non-linear capacitances of the device are modeled and considered in the analysis. The model is validated with a double-pulse tester and a boost converter. The developed method was compared with known second order and circuit simulation models and found to yield improved results. The two studies detailed here lay the foundation for optimizing the performance of GaN devices while keeping them in their safe operating regions.

Wide Bandgap Semiconductor Power Devices: Materials, Physics, Design and Applications provides readers with a single resource on why these devices are superior to existing silicon devices. The book lays the groundwork for an understanding of an array of applications and anticipated benefits in energy savings. Authored by the Founder of the Power Semiconductor Research Center at North Carolina State University (and creator of the IGBT device), Dr. B. Jayant Baliga is one of the highest regarded experts in the field. He thus leads this team who comprehensively review the materials, device physics, design considerations and relevant applications discussed. Comprehensively covers power electronic devices, including materials (both gallium nitride and silicon carbide), physics, design considerations, and the most promising applications Addresses the key challenges towards the realization of wide bandgap power electronic devices, including materials defects, performance and reliability Provides the benefits of wide bandgap semiconductors, including opportunities for cost reduction and social impact

This dissertation investigates the propagation of information between models of disparate computational complexity and simulation domains with specific focus on the modeling of wide bandgap semiconductors for power electronics applications. First, analytical physics models and technology computer-aided design numerical physics models are presented. These types of physics models are contrasted by ease of generation and computational complexity. Next, processes generating transient simulations from these models are identified. Mixed-mode simulation and behavioral device models are established as two available options. Of these two, behavioral models are identified as the method producing superior computational performance due to their much-reduced simulation time. A comparison of switching performance for two wide bandgap field-effect transistors manufactured with the same process is next presented. Empirical and simulated switching results demonstrate that available models predict the slew rates reasonably well, but fail to accurately capture ringing frequencies. This is attributed to two primary causes; the modeling tool used for this comparison is incapable of producing a sufficiently high-quality fit to ensure accurate prediction and the devices are sensitive to parasitic values beyond the measurement uncertainty of the characterization hardware. To remedy this, a two-fold approach is necessary. First, a new model must be generated which is more capable of predicting steady-state performance. Second, a characterization procedure must be produced which tunes parameters beyond what is possible with empirical characterization. To the first point, a novel model based on the Curtice model is presented. The novel model adapts the Curtice model by adding gate-bias dependence to model parameters and introducing an exponential smoothing function to account for the gradual transition from linear to saturation exhibited by some wide bandgap field-effect transistors. Care is taken to model forward conduction, reverse conduction, and transfer characteristics with high accuracy. Non-linear capacitances are then modeled using a charge-based lookup table demonstrated by previous work in the literature to be effective. Thermal performance is accounted for with both the incorporation of thermal scaling factors and a thermal RC network to account for joule-heating. The proposed model is capable of capturing device steady-state and small-signal performance more precisely than previous models. A tuning and optimization procedure is next presented which is capable of tuning device model parasitic values within uncertainty bounds of characterization data. This method identifies the need for and introduces new model parameters intended to account for dispersive phenomena to a first degree. Pairing this method with the aforementioned model, significant improvements in transient agreement can be achieved for fast-switching devices. A method is also presented which identifies and quantifies the impact of parameters on transient performance. This process can be used to remove model parameters from the tuning set and possibly decouple parameter tuning. The propagation of these fully-tuned device and circuit models to the system level is next discussed. The cases of a buck converter and double pulse test are used as examples of dc switching circuits which may be used for switching characterization and to account for switching losses. Simulation is used to demonstrate that these circuits, when using similar components, produce comparable results. This allows the use of double pulse tests for switching characterization in simulation, thus eliminating the need for quasi-steady-state conditions to be reached in converter simulation. Methods are proposed for the inclusion of this data into system-level models such that simulation time will be minimally impacted. When used in conjunction, the methods presented in this chapter are sufficient to propagate information from the physics level all the way through to the system level. If specific circuits and system components are known, the impact of including a theoretical device can be assessed. This lends itself to advanced design of each type of model by analyzing the interactions predicted by various levels of models. This has serious implications for accelerating the deployment of wide bandgap semiconductor in power electronics by addressing the primary concerns of reliability and ease of implementation. By using these methods, devices, circuits, and systems can each be optimized to fully benefit from the theoretical advantages presented by wide bandgap semiconductor materials.