Silicon carbide for new energy vehicles is expected

Silicon has always been the most commonly used material for the manufacture of semiconductor chips, mainly because of the large reserve of silicon, the cost is relatively low, and the preparation is relatively simple. However, the application of silicon in the field of optoelectronics and high-frequency high-power devices is hindered, and the operation performance of silicon at high frequencies is poor, which is not suitable for high-voltage applications. These limitations have made it increasingly difficult for silicon-based power devices to meet the needs of emerging applications such as new energy vehicles and high-speed rail for high-power and high-frequency performance.

In this context, silicon carbide has come into the spotlight. Compared with the first and second generation semiconductor materials, SiC has a series of excellent physicochemical properties, in addition to the band gap width, it also has the characteristics of high breakdown electric field, high saturation electron velocity, high thermal conductivity, high electron density and high mobility. The critical breakdown electric field of SiC is 10 times that of Si and 5 times that of GaAs, which improves the withstand voltage capacity, operating frequency, and current density of SiC base devices, and reduces the conduction loss of the device. Coupled with a higher thermal conductivity than Cu, the device does not require additional heat dissipation devices to use, reducing the overall machine size. In addition, SiC devices have very low conduction losses and can maintain good electrical performance at ultra-high frequencies. For example, changing from a three-level solution based on Si devices to a two-level solution based on SiC can increase efficiency from 96% to 97.6% and reduce power consumption by up to 40%. Therefore, SiC devices have great advantages in low-power, miniaturized and high-frequency applications.

Compared with traditional silicon, the use limit performance of silicon carbide is better than that of silicon, which can meet the application needs of high temperature, high pressure, high frequency, high power and other conditions, and the current silicon carbide has been applied to RF devices and power devices.

Silicon carbide materials can make the size of the device smaller and smaller, and the performance is getting better and better, so in recent years, electric vehicle manufacturers have favored it. According to ROHM, a 5KW LLCDC/DC converter, the power control board was replaced by silicon carbide instead of silicon devices, the weight was reduced from 7kg to 0.9kg, and the volume was reduced from 8755cc to 1350cc. The size of the SIC device is only 1/10 of that of the silicon device of the same specification, and the energy loss of the SI CARBIT MOSFET system is less than 1/4 of that of the silicon-based IGBT, which can also bring significant performance improvements to the end product.