Silicon carbide (SiC) diode is a high-performance device based on wide bandgap semiconductor materials. Compared with traditional silicon diodes, its characteristics are significantly optimized, especially suitable for harsh environments such as high power, high frequency, and high temperature. The following is a comprehensive analysis of its core characteristics and advantages:
1、 High voltage and high power density characteristics
1. High dielectric breakdown field strength
The dielectric breakdown field strength of SiC is about 10 times that of silicon. Under the same rated voltage, SiC diode chips are smaller in size and have higher power density. For example, the volume of a 650V SiC diode can be reduced by 60% compared to silicon devices.
2. High voltage bearing capacity
The breakdown voltage of SiC diodes can reach over 650V (some models even reach 2400V), significantly higher than that of silicon devices, and is suitable for high-voltage scenarios such as new energy vehicle charging and solar inverters.
2、 Efficient switch and low loss characteristics
1. No reverse recovery current
SiC diodes are unipolar Schottky structures that only conduct through majority carriers (electrons), with almost zero reverse recovery charge, eliminating reverse recovery current spikes, and reducing switching losses by more than 70%.
2. Fast switching speed
The electronic saturation speed is high, combined with low parasitic capacitance, and the switching speed is more than 10 times faster than silicon devices, making it suitable for high-frequency circuits such as LLC resonant converters and PFC circuits.
3. Low dynamic loss
The forward recovery loss is almost zero, and the reverse leakage current remains extremely low at high temperatures (such as Vishay's third-generation SiC diode with room temperature leakage current of only 1.3 µ A), significantly improving system efficiency.
3、 Excellent thermal performance
1. High thermal conductivity
SiC has a thermal conductivity 3.5 times that of silicon, with stronger heat dissipation capacity per unit area, reducing reliance on heat sinks and simplifying system design.
2. High temperature stability
The working temperature range is wide (-55 ° C to 175 ° C), and the conductivity changes little at high temperatures, avoiding the risk of thermal runaway of silicon devices. It is suitable for high temperature environments such as electric vehicles and industrial equipment.
4、 Reliability and safety improvement
1. Parallel current sharing capability
Positive voltage drop has a positive temperature coefficient and can be safely used in parallel without the need for additional current sharing circuits, while silicon devices are prone to thermal runaway due to negative temperature coefficients.
2. Surge resistance and high robustness
Some models, such as Vishay MPS structured diodes, support surge currents up to 2.5 times the rated current, enhancing overcurrent protection capabilities.
5、 Electromagnetic Compatibility (EMI) Optimization
The soft switching characteristics of SiC diodes significantly reduce the rapid spikes of reverse recovery current, minimize conduction and radiation interference, simplify EMI filtering design, and are particularly suitable for high switching frequency scenarios (such as data center power supplies).
6、 Application scenarios and typical products
1. Automotive electronics
The 650V automotive grade SiC diode (STPSC series) from Ruyifa Semiconductor (ST) is used for car chargers to increase power density and reduce weight.
2. New energy system
In solar inverters, SiC diodes can reduce energy consumption by 70% and support efficient operation over a wide temperature range.
3. Industrial power supply
Vishay's third-generation SiC Schottky diodes (such as the VS-3C series) are suitable for AC/DC converters, reducing the forward voltage to 1.46V and improving energy efficiency.
Silicon carbide diodes have demonstrated significant advantages in high-voltage, high-temperature, and high-frequency scenarios through material and structural innovation, becoming an important technological direction in the field of power electronics. Although its cost is still higher than that of silicon devices, with technological advancements such as Vishay's thin wafer technology and large-scale production, the penetration rate of SiC diodes in fields such as new energy vehicles and renewable energy will continue to increase.