Silicon carbide (SiC) technology has reached the tipping point, the state when undeniable advantages push a technology into rapid adoption.
Today, designers looking to stay competitive and lower long-term system costs are turning to SiC-based technologies for many reasons, including these:
- To reduce total cost of ownership: SiC-based designs, while requiring upfront investment, deliver system cost reductions via energy efficiency, smaller system size and reliability.
- To overcome design challenges: SiC’s properties enable designers to develop smaller devices that run cooler, switch faster and operate at higher voltages.
- To increase reliability and performance: With smaller, cooler devices, designers are free to make more innovative design choices that more readily meet market need.
Most electronics today rely on metal oxide semiconductor field effect transistors (MOSFETs), invented in 1959 at Bell Labs and widely adopted during the early 1960s. MOSFETs control the electrical conductivity of the device channel by changing voltage applied on the gate terminal, which is enabling signal amplification or switching and power processing.
Silicon (Si) is still used as a major material to build MOSFETs, but today’s equipment performance demands is pushing Si technology to material limits.
SiC advantages over traditional Si
Energy usage and its conversion from source to final application has been a subject of development ever since horsepower meant exactly that, and the design of a plough was critical to how many days it would take to prepare a field for planting.
Today we think more about electrical energy and power conversion from a generator output to an end-voltage for a host of applications, be it 0.6VDC for a processor, 24VDC to 500VAC for an industrial motor drive or 400VDC to charge an EV battery. The conversion process invariably uses power semiconductor switches and Si-based types have been dominant for decades in the form of Si-MOSFETs and IGBTs.
Losses in these switches make them less efficient than SiC. Reducing power waste and heat is a primary focus in minimizing operating costs and achieving energy efficiency.
In recent years, alternative materials to silicon have become viable in the form of SiC and Gallium Nitride (GaN). Both have characteristics that enable step improvements in efficiency of power conversion. These wide bandgap devices are not a simple substitution for Si. Application circuit designs must match to extract full performance benefits. (Figure 1 shows the main differences between the materials.)
Si, SiC and GaN – conduction losses
Si-IGBTs have a nearly constant on-state collector-emitter saturation voltage that with collector current sets conduction losses. Si-MOSFETS have an on-state resistance so that power dissipated is I.R(ON)2 (noted as: , which can be prohibitive at high current levels.
At low voltage and low to medium power, Si-MOSFETs with low R(ON) can have less conduction loss than IGBTs. SiC and GaN materials have a much higher critical breakdown voltage than Si, allowing for a thinner drift layer and higher doping concentration. This leads to lower on-resistance for a given die area and voltage rating, providing for greater efficiency through reduced power loss.
Additionally, SiC has a thermal conductivity more than three times better than Si, enabling the use of smaller die for the same temperature rise. SiC and GaN also provide efficiency improvements over Si by having higher maximum operating temperatures, limiting device stress.
Learn more about the advantages of Infineon’s CoolSiCTM technology.