Silicon Carbide MOSFETs

Silicon carbide MOSFETs (also referred to as SiC MOSFETs) provide significant performance advantages over their silicon counterparts, including faster switching speeds for power conversion circuits; improved reliability by eliminating voltage spikes; lower power losses in components like inductors, capacitors & filters; and smaller designs.

SiC is known for its wide bandgap, making it suitable for high temperature applications such as traction inverters and motor drives. But what other benefits can this electronic component bring to the table?

High Breakdown Voltage

SiC MOSFETs feature high breakdown voltages that enable them to withstand higher operating temperatures, making them especially suitable for applications involving elevated currents and voltages, such as switch mode power supplies, voltage converters, or high-power servo motor drives.

Unipolar silicon carbide devices offer significant advantages due to their thin drift layer compared to bipolar silicon devices, enabling a lower resistance voltage blocking layer construction process and thus higher on-state current generation.

SiC semiconductors stand out by their wider bandgap, which enhances electron mobility, enabling electrons to traverse more quickly through channels and thus decreasing RDS(ON) significantly. Furthermore, their greater energy storage capacity enables switching devices made from SiC to operate at faster switching frequencies compared with silicon counterparts; this translates to lower energy losses during switch-on and switch-off phases and therefore power electronics applications can benefit greatly from using this material.

These advantages allow for smaller magnetics, leading to reduced system size and weight. Furthermore, increased efficiency levels offer cost savings while high frequency operation reduces component temperature thus decreasing risk of thermal runaway.

These qualities make silicon-based devices particularly suitable for applications that operate under challenging environments and conditions, where their reliability may be restricted. Examples include traction inverters, motor drives and photovoltaic solar inverters that operate under such circumstances.

Silicon carbide MOSFETs can withstand temperatures up to 1200V while still offering outstanding performance. They’re an ideal choice for hard and resonant switching topologies which use high frequencies to drive their device, thus reducing component size, increasing efficiency, and increasing lifelong reliability.

Silicon carbide mosfets from our selection come in various sizes and configurations ranging from low-cost commercial TO-247 packages to fully hermetic TO-258 ones, offering wide working voltage ranges between 200V to 1200V for wide working voltage applications like electric vehicle charging stations or electric vehicles themselves. They’re built tough enough to withstand even harsh environments.

High Current Density

Silicon Carbide (SiC), commonly referred to as carborundum, is an all-natural compound composed of silicon and carbon that is used as a semiconductor material when doped with impurities like aluminum, boron, gallium or nitrogen/phosphorus impurities – creating P-type and N-type semiconductor regions needed for power electronics devices.

Contrary to silicon, SiC’s wide bandgap allows for higher critical breakdown voltage ratings in smaller packages with reduced on-state resistance per area and improved switching performance, leading to lower QONSiC values and thus increased switching frequencies and thus greater energy efficiency in power conversion applications.

High blocking voltage and fast switching are essential features in high-frequency power conversion applications, such as those found in electric vehicle chargers, server power supplies and renewable energy systems. A higher power density allows smaller inductors, capacitors and transformers which in turn leads to more compact system designs at reduced costs.

SiC MOSFETs provide faster switching response and greater reliability compared to traditional power semiconductors, leading to increased efficiency, smaller inductors, transformers and filters and overall system costs reductions.

SiC MOSFETs not only boast superior switching speeds and blocking voltage capabilities, but they also boast greater temperature tolerances compared to their silicon counterparts, making them suitable for more demanding applications operating at elevated temperatures.

Though silicon carbide power MOSFETs often require high blocking voltages for protection purposes, there are high-efficiency converters which don’t. Such converters typically need lower gate-drive voltages that can be achieved using simpler driver circuits; one key challenge with this type of converter is ensuring its gate drive voltage doesn’t cause excessive on resistance in its embedded Schottky barrier diode (SBD), which could compromise reliability of device.

Toshiba has devised a solution to this problem by adapting their basic MOSFET structure with a SBD that prevents the PN diode from being energized, significantly improving reliability of 1.2kilovolt class SiC MOSFETs used in bus converters, electric vehicle chargers, solar PV inverters and motor drives.

Low On-Resistance

Silicon carbide enables significantly higher blocking voltage and lower on-state resistance than standard silicon power MOSFETs, combined with lower drive current requirements than their silicon counterparts. As a result, SiC devices are quickly replacing silicon MOSFETs and IGBTs in many applications including electric vehicle traction inverters, industrial power supplies, and photovoltaic grid inverters.

SiC’s wider bandgap allows electrons to flow more freely through its channels, leading to thinner depletion regions and reduced on-resistance (RDS(on). SiC devices typically exhibit gate-source on-resistance of 6mOhm at 750 V and offer significant system efficiency gains without incurring additional design or packaging costs.

Over time, silicon-based power MOSFETs have been continuously refined to reduce their specific on-resistance. At 650 V rated devices however, their specific on-resistance has reached its limit within current technology.

SiC devices present plenty of opportunities to further reduce on-resistance and significantly lower switching and conduction losses, as manufacturers strive to enhance device performance with each successive generation. Manufacturers generally reduce on-resistance by 30%-40% each generation in an attempt to boost device performance.

Silicon carbide’s superior electron mobility and thermal conductivity allow electrons to traverse the channel more quickly, further lowering on-resistance. Furthermore, its thermal conductivity enables heat dissipation more rapidly which further minimizes on-resistance and switching losses.

Engineers looking to achieve low specific on-resistance must consider various elements, including number of transistors in a package, cell pitch and pattern, metallization scheme and substrate size – not forgetting resistances introduced during packaging which may add further to its on-resistance.

UnitedSiC (now Qorvo) manufacturers are actively working to lower the specific on-resistance of SiC devices by shrinking device sizes, optimizing metal gate stacks and ensuring substrate sizes are adequate. Their Gen 4 silicon carbide field-effect transistors have an exceptionally low on-resistance of only 6mOhm in a TO247-4L package – significantly reducing system weight, complexity and cost for high power applications such as electric vehicles, data centers or photovoltaic systems.

High Thermal Conductivity

Silicon carbide MOSFETs boast not only wide band gaps and high blocking voltage capabilities, but they also boast superior thermal conductivity – which enables rapid heat dissipation from smaller and lighter devices for greater levels of performance.

SiC’s superior thermal conductivity stems from its higher electron mobility over silicon. This high electron mobility accelerates charge carrier velocity, decreasing both conduction and switching losses while its wider band gap reduces leakage current at high temperature applications – making SiC an excellent choice for power electronics applications.

SiC MOSFETs have become the go-to product for high-efficiency power conversion systems such as AC/DC converters and inverters, benefiting EVs and renewable energy systems alike with increased power density that extends driving ranges while improving charging infrastructure and solar inverters.

Silicon carbide MOSFETs stand out as power semiconductors by their ability to operate under various ambient conditions and temperatures with relative ease, making them particularly well suited to operating reliably in high temperature environments. Due to this unique property, silicon carbide MOSFETs feature an extended operating temperature range than other silicon-based devices; providing more stable performance under high-temperature environments.

SiC MOSFETs combine excellent reliability with robustness and compactness to make them an excellent choice for medium-voltage applications such as Auxiliary Power Units (APUs) and Traction Power Units on trains, buses, light rail vehicles and heavy-duty cargo/delivery trucks. Such systems require high efficiency power electronics with minimal turn-on/off energies to reduce total system, maintenance and operational costs while remaining cost effective over their lifespan.

Attaining these advantages requires designing efficient, robust, and cost-effective power conversion systems using SiC MOSFETs. To do this successfully requires designing gate drive circuits to meet voltage and current specifications as well as providing efficient cooling solutions that manage power dissipation of devices. Galvanic isolation techniques should also be utilized to help mitigate voltage transition transients while acting as a barrier between different circuit sections.