Advantages of Silicon Carbide MOSFETs

Wide bandgap power semiconductor devices such as silicon carbide MOSFETs have become an increasingly popular component in electronic circuit designs, as their superior performance over conventional silicon-based power semiconductors make them attractive solutions.

MOSFETs consist of three terminals known as source, drain, and gate. Applying positive voltage to the gate creates an electric field which allows current to flow between source and drain to turn on the device.

Low On-State Resistance

Silicon carbide MOSFETs feature lower on-state resistance than their silicon counterparts, enabling higher switching frequencies and decreasing switching losses, leading to improved system efficiencies in systems such as grid conversion or electric vehicle use. High speed switching in these systems helps reduce magnetic element sizes and in turn decrease system size, weight and costs.

RDS(ON) of a MOSFET measures its current flow when not switched on or off. It can be calculated as the inverse of its voltage drop across it; or more specifically: ROUT = GDS / TR.

Silicon carbide MOSFETs possess all these attributes for low on-state resistance, making them the ideal choice for power electronic circuits.

Silicon carbide MOSFETs boast the added advantage of having on-state resistances less susceptible to fluctuation due to temperature than silicon counterparts, enabling wider operating temperature ranges in electronics systems and eliminating the need for complex cooling solutions in order to maintain performance levels.

SiC MOSFETs feature 10 times greater critical breakdown strength compared to regular silicon devices, enabling higher switching frequencies that enable smaller magnetic elements and reduced system weight/cost.

Designing systems using SiC MOSFETs requires careful consideration to meet their maximum switching frequency, since any increase can increase DC bus ringing and noise, necessitating more sophisticated EMI filtering and fault handling mechanisms.

ST’s silicon carbide MOSFETs feature an extended voltage range from 650V to 2200 V and deliver outstanding switching performance and extremely low on-state resistance per area, enabling designers to create more energy-efficient and compact systems. Furthermore, their temperature ratings of up to 200degC make them suitable for demanding applications such as bidirectional on-board chargers for electric/hybrid vehicles or renewable energy generation.

High Voltage Breakdown

Silicon carbide (SiC) is an unconventional semiconductor material with the potential to deliver power efficiency gains and cost savings across a variety of applications, from automobiles and consumer electronics to IT. SiC can operate at higher temperatures while still switching faster with a significantly reduced ON resistance than Si-based alternatives.

SiC is a p-type semiconductor material, while silicon has a p-n junction structure with heavily doped n-layer to form a negative potential barrier and prevent electron tunneling (Zener breakdown). Due to SiC’s larger bandgap, its diodes can have much thinner n-layers without compromising critical electric field strength (as indicated by red triangle in Figure 2). Therefore, MOSFETs with SiC MOSFETs may offer lower on-state resistances and higher switching speeds at similar voltage levels.

SiC MOSFETs can boast much higher current densities than their silicon counterparts due to a significantly smaller gate oxide thickness and increased channel length, enabling them to carry more current at lower voltage, which in turn decreases switching losses and dissipation.

SiC MOSFETs also benefit from being able to withstand higher temperatures, which allows them to improve their performance by increasing operating voltage and decreasing on-state resistance, and by operating at faster switching speeds which may prove advantageous in applications like high voltage power supplies and converters.

Silicon carbide’s use in MOSFET fabrication is driven by its superior electrical properties compared to silicon, making it more suitable for many modern electronic circuits. SiC substrate provides significant advantages in terms of power density per chip size, switching frequency and lifecycle reliability.

SiC MOSFETs can enable higher switching frequencies while also producing greater current densities and on-resistances, especially when used in hard or resonant switching topologies like LLC and ZVS. To do so effectively requires drivers that can generate the appropriate turn-on voltage and provide fast yet stable thyristor-like control; On Semiconductor has addressed this by developing a driver for high-voltage silicon carbide MOSFETs compatible with popular IGBT or MOSFET drivers.

High Current Density

Silicon carbide offers much higher electron mobility than silicon, enabling it to accommodate greater current in a shorter space and therefore provide lower on-resistance for power applications with high switching frequencies. Furthermore, SiC’s wider bandgap allows for thinner depletion regions which reduce switching losses further reducing conduction and switching losses in comparison with traditional silicon-based power semiconductors allowing designers to create smaller systems while still meeting performance and reliability goals of existing designs.

Wolfspeed’s Gen3 3300 V bare die silicon carbide MOSFETs are providing smaller, more cost-efficient power conversion systems by significantly reducing system loss and costs. Their higher switching frequency than their silicon counterparts enables smaller inductive and capacitive components, leading to reduced system size overall.

Improved thermal conductivity helps lower cooling requirements, further reducing equipment weight and volume requirements. Our SiC MOSFETs’ higher switching frequencies enable increased energy density as well as supporting various power conversion topologies such as hard-switching LLC and ZVS power conversion topologies.

High performance silicon carbide MOSFETs bring multiple advantages to industrial uninterruptible power supplies (UPS), photovoltaic solar inverters and Electric Vehicle charging stations. Their reduced losses can save 30% over traditional silicon solutions while remaining more reliable with longer lifespans.

SiC MOSFETs differ from silicon devices in that they can withstand higher temperatures, making them suitable for power conversion systems operating at elevated voltages, such as traction inverters or DC-DC converters. Their robust nature also enables them to work reliably even under harsh environments such as high temperature or humidity levels.

However, due to their high switching frequencies and rapid state transitions between on and off states, validating SiC power devices can present unique challenges when measuring performance. If not measured correctly, devices can cause spurious ringing due to rapid transitions. In Tektronix’s new application note on Effective Measurement of Signals on SiC Power Devices they offer tips for mitigating these effects by using differential probes such as the THDP0200 to ensure accurate source/drain voltage measurements on SiC devices.

High Efficiency

Efficiency is of utmost importance in power electronics, particularly at higher voltage levels. Efficient designs allow systems to be built at smaller footprints, lighter weights and reduced system costs; benefits which ultimately translate to massive advantages for end consumers. Silicon carbide (SiC) semiconductors are among the most efficient available, providing wider bandgaps than silicon and making them more suitable for use at higher temperatures, voltages and frequencies.

SiC is distinguished by a wider energy gap that makes higher switching speeds possible and significantly increases power conversion efficiency. Lower switching losses also translate to decreased heat dissipation in MOSFET’s ON state as well as quicker transitions between ON and OFF states, thus further decreasing power losses while improving reliability.

High-speed operation enables the use of smaller, higher current density MOSFETs that can be packaged together in larger areas for easy packaging, thereby drastically decreasing overall size and cost of the power converter system.

SiC is known for its superior electron mobility, enabling it to outperform silicon at similar temperatures by offering lower gate drive currents, power consumption and loss. Furthermore, this also reduces magnetic element sizes significantly improving efficiency while decreasing component sizes and costs.

Silicon Carbide’s wide bandgap allows for thinner depletion regions between source and drain terminals, leading to lower on resistance values and temperature stability – both features which enable SiC to meet power industry RDS(on) values with lower supply voltage requirements.

Nexperia’s first-generation 1200 V SiC MOSFETs feature shallow junction extensions, raised source and drain capacitance and an optimized ratio between gate-to-drain charge (QGD) and gate-to-source charge (QGS), giving them superior Miller turn-on instability performance with the same RDS(on). They even outshone silicon counterparts by covering a wider temperature range while keeping RDS(on) values constant across greater temperature variations.

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