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SiC vs GaN Transistors

Silicon carbide (SiC) is used in electric vehicles due to its wide bandgap and great thermal conductivity. SiC minimizes energy losses and withstands high heat, extending the life of the EV battery and other electronic components and reducing maintenance costs.

Gallium nitride (GaN) shares many characteristics with SiC while also minimizing RF noise. This is crucial in wireless applications, as noise can distort signals and transmit inaccurate information.

SiC: Its Wide Bandgap and Thermal Conductivity is Optimal for EVs

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SiC is optimal for high-voltage applications due to its wide bandgap. The bandgap refers to the minimum energy differential that needs to be applied between a  semiconductor’s conduction band and its valence band. In simple words, the energy that needs to be applied so that a semiconductor changes from being an insulator to a conductor. SiC’s dielectric breakdown (the voltage at which it becomes a conductor) is around 10x higher that of normal silicon, meaning electrons need much more energy to move, and there won’t be leakage currents when it shouldn’t. In the context of an electric vehicle this is optimal, as higher bandgap means lower energy losses and a longer battery life. It is estimated silicon carbide can extend an electric vehicle range by 10%, while saving space and reducing car weight.

SiC thermal conductivity is 3x better than Si, a desirable characteristic in an electric vehicle or an industrial application. EV batteries and inverters can generate a lot of heat during charging and discharging cycles given they operate at high voltage, so the high thermal conductivity of SiC helps to better dissipate heat. Its high thermal conductivity helps maintain lower temperatures in the car, resulting in less need for additional cooling systems and improving the overall efficiency of the vehicle. Keeping electronic components at lower temperatures normally results in longer lifespans, extending the operational life of the vehicle and reducing costs for the owner. Only the most critical parts of an electric vehicle will use silicon carbide, as it is much more expensive than normal silicon.

SiC also presents high chemical inertness and hardness. The firts refers to the material’s resistance to chemical reactions with other substances thanks to its stable atomic structure. The second refers to the material’s resistance to deformation and strain forces. These characteristics make SiC suitable to operate in harsh and high temperature environments.

GaN: Optimal for RF Devices Thanks to Low Noise

Gallium nitride (GaN) shares many characteristics with SiC: wide bandgap, high dielectric breakdown and very good thermal conductivity. However, it has one extra characteristic that makes it ideal for radiofrequency (RF) applications: low noise. Minimizng noise is crucial in RF applications to maintain the quality of the signal, as a noisy signal can transmit information inaccurately. GaN high saturation velocity (the maximum velocity electroncs can achieve) and low trapping effects (the tendency of electrons to get stuck) help reduce noise. GaN transistors also have low parasitic capacitance and resistance, meaning they can maintain clearer signal propagation. At high frequency, data transfer rates increase but signal wavelengths become smaller and noise can increase. GaN is extremely useful for these applications thanks to its low noise characteristics. GaN transistors also have high power density, meaning they can handle a high amount of power in a small area.

GaN technology is mainly used as a power amplifier in 5G base stations. 5G works on a millimiter-wave band and operates at high frequencies compared to its predecesors 4G and 3G. GaN transistors offer higher efficiency than other alternatives, meaning they can convert more input power into radiofrequency output power, reducing energy consumption at base stations, a key aspect as the demand for data-intensive applications keeps increasing. Its high power density also means GaN can produce more output power in a smaller footprint, a key parameter when deploying small cells. Its high dielectric breakdown allows to apply higher voltages without conducting, allowing for faster switching transitions.

GaN and SiC can also be combined to form a semiconductor compound known as Gan-on-SiC, although it’s not very common.

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SiC vs GaN Transistors

Silicon carbide (SiC) is used in electric vehicles due to its wide bandgap and great thermal conductivity. Gallium nitride (GaN) shares many characteristics with SiC while also minimizing RF noise.

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