Wide-bandgap Devices
This comprehensive video course on Silicon and Wide Bandgap Power Devices, provides an in-depth exploration of the fundamental physics, design, fabrication, and application of modern power semiconductor devices. Starting with the basics of semiconductor physics (Si, SiC, and GaN), the course systematically covers the operation and design of essential power components, including PiN diodes, Schottky Barrier Diodes (SBD/JBS), and various Power MOSFETs (Planar, Trench, and Super Junction). A major focus is placed on the superior performance of Wide Bandgap (WBG) materials, analyzing critical concepts like Avalanche Breakdown, Edge Termination, switching dynamics, and thermal management within power electronic circuits (Buck, Boost, Inverter) to enable high-efficiency, high-voltage applications.
Textbooks
Power Electronics: Converters, Applications, and Design
Ned Mohan, Tore M. Undeland, William P. Robbins · Wiley
Fundamentals of Silicon Carbide Technology
Tsunenobu Kimoto, James A. Cooper · Wiley
Semiconductor Power Devices
Josef Lutz, Heinrich Schlangenotto, Uwe Scheuermann, Rik De Doncker · Springer
Gallium Nitride and Silicon Carbide Power Devices
Jayant Baliga · World Scientific
Modules
Description: This introductory lecture provides a high-level overview of power electronics, power devices (diodes and transistors), and their wide range of applications from phone chargers to the electric grid. It details fundamental circuit topologies, including the Buck, Boost, and Inverter, and explains the critical role of packaging in power modules for thermal management. The module emphasizes the shift toward high-efficiency Wide Bandgap (WBG) devices.
Description: This video introduces the foundational physics of semiconductors, defining what they are and classifying them into elemental (like Si) and compound (like GaAs) types. It delves into the difference between intrinsic (pure) and extrinsic (doped) semiconductors, explaining concepts like covalent bonds, electron-hole pairs, and the role of donor/acceptor impurities in creating n-type and p-type materials.
Description: Continuing the discussion on semiconductor physics, this module focuses on charge carrier concentration and the Fermi-Dirac distribution at thermal equilibrium. It delves into the relationship between doping concentration and the resulting electron and hole mobility, and examines the impact of temperature on key material properties. This builds the quantitative foundation for device modeling.
Description: This final installment on semiconductor properties covers the mechanisms of drift and diffusion currents, which dictate charge movement under electric fields and concentration gradients. It introduces the continuity equation and examines how the lifetime of charge carriers impacts device switching speed and efficiency, especially in bipolar devices.
Description: The module begins the in-depth analysis of the P-N junction, detailing its formation and the resulting depletion region at equilibrium. It explains the effect of forward and reverse bias on the junction width and potential barrier, introducing the Shockley diode equation to describe the device's fundamental current-voltage (I-V) characteristics.
Description: This video focuses on the high-voltage limits of power devices by examining the mechanism of Avalanche Breakdown and how it is mitigated. It provides a formal comparison of key semiconductor properties—such as bandgap, critical electric field, and thermal conductivity—for Si, SiC, and GaN, demonstrating why Wide Bandgap materials are superior for high-power applications.
Description: This module is dedicated to the High-Voltage (HV) PiN Diode structure, which is essential for very high-power applications. It explains the role of the intrinsic (i) or drift layer in supporting a high blocking voltage and discusses the concepts of conductivity modulation and excess carrier lifetime in the forward-biased state.
Description: High-voltage devices require advanced techniques to prevent premature breakdown at the edges of the semiconductor chip. This module details Edge Termination methods for the PiN diode, focusing on structures like Junction Termination Extension (JTE) and Guard Rings to spread the electric field and maximize the breakdown voltage.
Description: This module moves to a practical design phase, demonstrating the use of 2D device simulators to model the electric field profile and evaluate the effectiveness of various Edge Termination designs. It shows how simulations are used to optimize the geometry (e.g., doping and length) of JTEs and guard rings for maximum breakdown voltage.
Description: Focusing on the ON-state operation of the PiN diode, this module analyzes the physics of forward bias. It details the injection of excess carriers into the drift region and the resulting conductivity modulation, which significantly reduces the series resistance and enables high current flow.
Description: Part 2 continues the analysis of the PiN diode's ON-state, focusing on the trade-offs between forward voltage drop and switching speed. It discusses the effects of carrier lifetime control and temperature on the stored charge and the power loss during forward conduction.
Description: This practical module teaches students how to interpret the technical specifications found on a commercial PiN Diode datasheet. It covers key parameters like $V_{F}$ (Forward Voltage), $I_{RRM}$ (Reverse Recovery Current), $Q_{RR}$ (Reverse Recovery Charge), and $V_{BR}$ (Breakdown Voltage), and how these relate to device performance in an application.
Description: This module introduces the Schottky Barrier Diode (SBD), a unipolar device that is superior in fast-switching applications due to the absence of minority carriers. It explains the formation of the metal-semiconductor junction and the relationship between the Schottky barrier height and the forward voltage drop.
Description: Part 2 explores the detailed I-V characteristics of the Schottky diode, focusing on the trade-off between forward voltage and reverse leakage current. It discusses the impact of electric field and image-force lowering on the barrier height and introduces practical methods for fabricating a stable, low-leakage Schottky contact.
Description: The final part on SBDs analyzes the phenomenon of reverse leakage and soft breakdown in the context of wide bandgap materials like SiC. It compares SBD performance to PiN diodes, concluding with a discussion on the limitations and advantages of the Schottky diode in high-temperature, high-voltage switching converters.
Description: Similar to the PiN diode analysis, this module uses device simulation tools to model the internal physics and performance of the Schottky diode. It demonstrates how to simulate the electric field at the metal-semiconductor interface, optimize the drift region, and predict the I-V characteristics to minimize reverse leakage.
Description: This module introduces the Junction Barrier Schottky (JBS) diode (also known as the Merged PiN Schottky or MPS diode), a hybrid structure that combines the low $V_{F}$ of the SBD with the robust blocking capability of a PiN junction. It details the fabrication process steps required to integrate both structures on a single chip.
Description: The focus shifts to the geometric and mask layout design of the JBS diode. The video explains the critical relationship between the P-N junction width and spacing in the JBS structure, and how this geometry is optimized to balance the low $V_{F}$ during forward conduction and the maximum blocking voltage during reverse bias.
Description: The series transitions to power transistors with the MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). This module explains the device's structure (Source, Gate, Drain) and fundamental operation principle, focusing on the formation of the inversion channel under the gate oxide that controls current flow.
Description: Part 2 delves into the MOSFET's I-V characteristics, examining the linear and saturation regions of operation. It discusses the critical parameters that define performance, such as threshold voltage ($V_{TH}$), transconductance, and the mechanisms that limit current at high gate voltages.
Description: This module dissects the total ON-resistance ($R_{ON}$) of the MOSFET, breaking it down into its various components (e.g., channel resistance, drift region resistance). It then uses device simulation to verify the calculated $R_{ON}$ and optimize the design for low conduction losses.
Description: Continuing the simulation topic, this video focuses on modeling the MOSFET's blocking state to ensure the design can withstand the required breakdown voltage. It demonstrates how to simulate the electric field distribution across the drift region and the gate oxide to prevent both oxide and avalanche breakdown.
Description: This module addresses the dynamic behavior of the MOSFET, analyzing the switching speed and associated energy losses during turn-on and turn-off. It also introduces the concept of ruggedness, focusing on the device's ability to withstand transient overvoltage (e.g., Avalanche Energy) and short-circuit conditions.
Description: This module begins the detailed discussion on Power MOSFET fabrication and its mask layout. Part 1 focuses on the initial process steps, including epitaxial growth, well and channel implantation, and the formation of the gate oxide and polysilicon gate electrode.
Description: Part 2 continues the fabrication process, covering the later steps such as source/drain contact formation, interconnect metalization, and passivation. It relates the final physical structure to the mask layout design rules and discusses how yield is affected by process variations.
Description: A critical safety and reliability topic, this module is entirely dedicated to the Short-Circuit Withstand Time ($t_{SC}$) of the power MOSFET. It examines the mechanisms of self-heating and thermal failure under a short-circuit fault and discusses design techniques, such as limiting the transconductance, to enhance $t_{SC}$.
Description: This module introduces the Super Junction (SJ) or CoolMOS technology, a revolutionary structure that overcomes the conventional Silicon limit trade-off between $R_{ON}$ and breakdown voltage. It explains the concept of charge balancing using P-columns and N-drift regions and details how this drastically lowers the specific ON-resistance.
Description: The final module focuses on the Trench MOSFET structure, where the gate is placed in a vertical trench etched into the silicon. It compares the Trench structure to the Planar structure, highlighting its advantage of a higher channel density and lower $R_{ON}$, while also discussing the design challenges related to the high electric field concentration near the trench corner.