Wide bandgap (WBG) power semiconductors are semiconductor materials with a larger energy bandgap than traditional semiconductors like silicon (Si). The energy bandgap is the difference in energy between the valence band where electrons are normally present and the conduction band where electrons can move freely to conduct electric current. Materials with a wider energy bandgap can operate at higher voltages, temperatures, and frequencies, making them ideal for various high-performance applications.

The commonly used WBG power semiconductors are gallium nitride (GaN) and silicon carbide (SiC). They offer significant advantages over traditional silicon semiconductors for power electronics applications.

Features of WBG Power Semiconductors

• Higher Operating Voltages: The breakdown field measures a material's dielectric strength, indicating the energy required to breach the bandgap. Gallium nitride's breakdown field is 3.3 MV/cm, and silicon carbide's is 3.5 MV/cm, compared to silicon's 0.3 MV/cm. This higher breakdown field makes SiC and GaN nearly ten times more capable of handling higher voltages. This capability facilitates the development of more compact and efficient power conversion systems.
• Higher Switching Speed: Wide bandgap materials exhibit higher electron mobility and electron saturation velocity, enabling switching frequencies up to ten times higher than silicon. Electron mobility, which indicates the speed at which electrons can move through a material, is 2,000 cm²/Vs for gallium nitride (GaN) and 650 cm²/Vs for silicon carbide (SiC). GaN's high electron mobility makes it particularly suitable for high-frequency applications.
• Higher Operating Temperature: Wide bandgap materials can operate at higher temperatures compared to standard silicon. Generally, wide bandgap devices can function up to 200°C, depending on the package's tolerance, whereas silicon is limited to 150°C. Thermal conductivity, a measure of a material's ability to transfer heat, is crucial as material inefficiencies generate heat during high-power applications. The more heat a material retains, the more its electrical characteristics change. Gallium nitride has a thermal conductivity of 1.3 W/cmK, while silicon carbide has a thermal conductivity of 5 W/cmK, making SiC advantageous for high-power and high-temperature applications.
• Improved Efficiency: Wide bandgap semiconductors have reduced switching and conduction losses, resulting in power conversion efficiencies exceeding 99%, compared to around 97% for silicon. This higher efficiency saves energy and reduces cooling requirements.                            

Note: 4H-SiC and 6H-SiC are 4-layered and 6-layered polytypes of SiC with hexagonal symmetry.

Applications of WBG Power Semiconductors

• Electric Vehicles: WBG semiconductors are used in traction inverters, power management DC-DC converters, and fast-charging onboard chargers (OBCs). They are also suitable for low-to-medium speed OBCs, air conditioners, and the auxiliary loads of electric vehicles with low-to-medium power or voltage requirements. As a result, WBG semiconductors enhance electric vehicles' efficiency, power density, and reliability.
• Renewable Energy: Wide bandgap (WBG) devices enhance solar string inverters by increasing power densities and efficiencies, thereby reducing size and weight. They also support higher photovoltaic ( PV) string voltages and power ratings, which improves overall performance in solar power systems. In energy storage systems (ESSs), WBG semiconductors enable bidirectional energy flow, enhancing efficiency and reliability for efficient battery charge and discharge. This integration is pivotal for hybrid solar and energy storage solutions. Additionally, WBG devices improve wind turbines by reducing power losses and increasing power density, resulting in more compact and efficient wind power systems.
• Data Centres: WBG semiconductors used in power supplies and Uninterruptible Power Supply (UPS) systems within data centers lead to more compact and energy-efficient designs, reducing operational costs and improving reliability. They improve the efficiency of DC-DC converters and voltage regulators used in server power management systems which leads to better overall energy efficiency and performance. WBG semiconductors contribute to more efficient control systems for air conditioning and cooling units, reducing energy consumption and operating costs. They support higher switching frequencies in power electronics thereby improving the performance of power converters and regulators used in data center infrastructure.
• Industrial Automation: The use of WBG semiconductors reduces energy consumption, lowers operating costs, and improves overall system efficiency in industrial automation equipment. They enable faster switching speeds and higher operating frequencies in power electronic devices resulting in quicker response times and more precise control in motor drives, inverters, and other automation components. Faster switching also reduces electromagnetic interference (EMI) and improves system reliability. As WBG semiconductors can operate at higher temperatures, they can be employed in industrial environments where equipment may be subjected to high ambient temperatures or require compact designs without extensive cooling systems. They are more resistant to thermal and mechanical stresses and exhibit better reliability and longer lifespan compared to silicon-based devices.
• Consumer Electronics: WBG-based power converters are employed in consumer electronics such as laptops, smartphones, and tablets to convert AC power into the DC power used by these devices. These converters significantly reduce energy losses—up to 90% compared to traditional silicon-based rectifiers. The advanced material properties of WBG semiconductors, including higher power density and thermal tolerance, enable more compact and efficient power conversion circuitry in consumer electronics. Their reliability at higher temperatures diminishes the necessity for bulky cooling systems, thereby enhancing the overall reliability of consumer electronics. WBG semiconductors also facilitate faster and more efficient charging solutions for smartphones and laptops, thereby improving user experience. Furthermore, WBG-based power supplies for TVs, gaming consoles, and home appliances offer superior efficiency and power density compared to conventional silicon-based designs.

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