Introduction
Silicon Carbide (SiC) is a wide-bandgap semiconductor that has become entwined within many our applications from power electronics, EVs, renewable energy systems, industrial applications, and many more. Their remarkable qualities and excellent characteristics such as high tolerance of voltages, high thermal conductivity, low switching losses, and so on means that thus these SiC devices are used in the harshest of environments. One parameter that has impact on is breakdown voltage which is essentially how much voltage can be used before its breakdown begins, leading to the device conducting uncontrollably, and hence its failure. In this article, we will go through the breakdown voltage of silicon carbide devices, what it measures, how does it differ from common silicon ones, and what is it affected by. “The breakdown voltage is an important consideration for power electronic devices like MOSFETs, diodes and Schottky barrier diodes (SBDs), both for selecting the voltage rating of the device and for consequences this has on the efficiency and reliability of the system as a whole.Breakdown Voltage in Silicon vs Silicon Carbide
The principal benefit of SiC as the semiconductor component compared to silicon (Si) is that its breakdown voltage is considerably greater, so that this translates into a much higher breakdown voltage in SiC devices than would be available in silicon devices making them appropriate for high voltage applications.
Silicon Breakdown Voltage: Due to the more limited nature of the materials involved – it has a relatively small bandgap and low dielectric strength – the breakdown voltage of silicon based devices is quite restricted, restricted for power devices like diodes, MOSFETs etc. to typically 400 – 600 volts.
Silicon Carbide Breakdown Voltage: The breakdown voltage of SiC is much higher due to the beneficial properties derived from the use of a wide bandgap semiconductor (3.26 eV); devices can in theory then be formed to breakdown at voltages from 1,000 volts up to 3,000 volts or more, with suitable doping and a suitable device structure. This is again is why SiC devices operate at very high voltages making it useful for high voltage products in assembly applications (power inverters and electric vehicles) and in renewable energy generation system applications.
Factors Influencing the Breakdown Voltage of All SiC Devices: There are a number of different factors that will affect the breakdown voltage of all silicon carbide devices, both intrinsic and extrinsic and concerning other matters to do with materials, device design and manufacture.
Next, we look at what happens to SiC devices when they breakdown at such high voltages.Actual material property – inherent high breakdown voltage of SiC at a material property level meaning this high breakdown voltage if told at makes a functioning jokester a secret quality of SiC. Also there is a wide bandgap in SiC which means the material supports a high electric field before breaking down. Further on this the material has reasonably good thermal conductivity to draw heat away from the high voltage region during operation reducing chances of thermal breakdown.
Doping concentration of silicon carbide – this varies the carrier populating the conduction band and changing the electric field present in the devices as a consequence. A lower doping concentration generally means the breakdown voltage of the device is higher since the material supports a higher electric field before reaching the critical value where breakdown occurs. Achieving the optimum concentration is not at all simple and also includes system parameters of performance like on resistance, switching speed and so on.
Device structure – how the device is laid out or constructed also broadly falls under here since for example in the case of MOSFETS we have trench structured devices modulus to improve voltage blocking capability, for diodes (and MOSFETS) the thicker the drift region the higher the breakdown voltage.
Lack of Edge Termination: If the edges are not terminated properly, they become more prone to breakdown at lower voltages, thus reducing the effective voltage rating of the device.
Temperature Effect: The breakdown voltage is dependent on the temperature and in the case of SiC devices, tends to increase with temperature.Being a strongly refractile material, such a device can obtain high values (higher than for silicon devices) 0f breakdown voltage at such high temperatures as for example, in the automobile industry with its high voltages, but it must be understood that there is a point at which this variation meets its match, and is no further use.
Without good edge termination, and the ability to divert the breakdown to its own structure away from the junction, the device is more likely to experience breakdown at the edges and fail, reducing its voltage rating. This imperfection is less significant if the device will achieve a higher breakdown voltage than its competition, say silicon.
Higher Power: SiC devices quoted at higher breakdown voltages fit the bill for higher powers without dropping out with thermal failure, thus paving the way for a more reliable and longer lifetime whole system.
Greater Reliability: More robust devices, less prone to failure than its competitors even in the worst of conditions, can combine mega high voltages with extreme temperatures, and high-radiation situations. Its proven reliability earns Unstrike your neck of the wood and use its renowned touch in electric vehicles and industrial equipment, and on the homefront renewables too.
Open New Doors: Its ability to take on more breakdown power, pays the way for SiC to apply itself to applications for which devil-touched silicon devices have no strong chance. Watch the Fit the Movie, for instance, and witness SiC MOSFETs toiling away in the warhorse electric vehicle powertrain opening the project to switch out faster rates and Higher power density leading to ever more viable and dependable Electric transport.
The Testing Procedures, and Standards
In order to qualify devices for use, Manufacturers shall make detailed measurements of their rated breakdown voltage. Testing facilities shall normally utilise special equipment for the purpose, designed to apply successively increasing applied voltage levels to the devices over a prescribed number of devices, under controlled lab conditions until their rated breakdown voltage is conclusively seen; once breached, the actual breakdown rating of the device is revealed.
There are also international standards and certifications which the devices should confirm to, in order for us to be confident SiC devices will deliver on their promise when put to work. These reggit into international electrotechnical commission (IEC) standards in the domain of power semiconductor devices; and of course standards that have arisen from automotive work and renewables trials of which the chips could go?
Conclusion
How the breakdown voltage of silicon carbide devices establishes one more thing among many that makes the devices a go for high power use. The materials used in SiC, as in the wide bandgap semiconductors used to form the die, and their high thermal conductivity leads to a raising up of breakdown voltage from its natural state way up from that of silicon devices making these Semiconducting beauties fit for transport courses in power electronics, renewable energy use and high temperature use.
Take the above considerations now and see where they take you, and a unit empire of higher efficiency, reliability, size reductions to make smaller power electronics join forces with Morton’s Float. And as SiC technology rolls on expect better and better from its high tendency towards higher breakdown voltage.