GaN vs Silicon: Which Power Device Should You Use

Have you heard something about GaN? It is quite popular nowadays. Not because it is a different technology that saves power, but because today electronics are moving towards miniaturization. And we need small power supplies that can handle a lot more current and power and dissipate less heat. This is all possible due to GaN MOSFETs available in SMT packages out there. There are a lot of new companies that took this idea and implemented it into small mobile and laptop chargers, and generated a lot of revenue. Now, because the technology is not mature enough, the bigger companies have started the research and development and are now producing their own OEM chargers. It is a revolution in the power electronics industry. Today, in this article, we will know the efficiency of these devices as compared to silicon ones. We will see how these devices help to replace the older technology.

Basics of GaN and Silicon:

Silicon (Si): We have been using silicon for almost 50 years, and it is quite mature and also widely used. But it is limited by intrinsic material properties, such as a lower breakdown field and electron mobility. Silicon can handle very high voltages (up to 1700V or even 6500V for IGBTs) and large currents, but at the cost of slower switching.

• Higher gate charge (Qg) compared to GaN.
• Larger output capacitance (Coss) leads to more switching losses.
• Limited breakdown voltage and thermal performance.

GaN (Gallium Nitride): A wide-bandgap semiconductor with much higher electron mobility and critical electric field strength. So what these things will do, higher mobility means higher speed of electrons, and higher critical field strength means it can handle a lot more voltages before damaging or breaking down. But this section is not mature yet, so we are using it in the range of 600V–900V range.

• Operate at higher voltages with lower conduction and switching losses.
• Handle faster switching speeds (up to several MHz).
• Reduce parasitic losses due to lower Qg and Coss.

Detailed Comparison table:

4 Major Factors in Which GaN is Unbeatable:

1. Higher Switching Frequencies

GaN devices can operate at frequencies above 1 MHz. It allows the smaller inductors and transformers to fit in directly and reduce the system cost. The PCB material also got change at high frequencies.

2. No Reverse Recovery Losses

Unlike traditional MOSFET technology, GaN FETs do not form a body diode from a structural point of view. Which means there's zero reverse recovery charge (Qrr). This eliminates switching losses during reverse conduction.  

3. Lower Conduction and Switching Losses

GaN has lower RDS(on resistance) and faster edge rates (up to 150 V/ns). It results in up to 82% lower losses compared to Si MOSFETs in certain PFC designs.

4. Smaller and Cooler Systems

Reduced losses translate into lower heat generation. Which means smaller heatsinks can be used to dissipate the heat, which gives a lighter cooling system.

Where Silicon Still Wins

Despite GaN's performance advantages, silicon MOSFETs still make sense in:

• Cost-sensitive designs
• Applications where switching frequencies are <100 kHz.
• Extremely high-voltage designs (>600 V)

Silicon remains a mature, well-understood and widely manufactured technology with excellent supply chain support. A choosing guide is given below, using which you can make design decisions.

Choosing Between GaN and Si MOSFETs

When deciding which device to use, consider:

1. Power level – GaN is ideal for where we have less than 10 kW of load otherwise, silicon is fine for low-cost and low-frequency needs.
   
2. Switching frequency – GaN's high speed is valuable for compact designs such as handheld gaming and chargers.
   
3. Thermal management – GaN's lower losses reduce cooling needs, which again points towards miniaturization.
   
4. Budget – Silicon is cheaper upfront but GaN can lower system-level costs. Such as cooling, transformers, and drivers.

No matter which device you choose—GaN or Silicon—the PCB quality remains a cornerstone of performance. That’s why many engineers use JLCPCB for reliable, cost-effective PCB manufacturing when testing both technologies.

Conclusion

So we have seen a detailed comparison of two technologies; the arrival of GaN technology marks a significant leap in power electronics design. Silicon MOSFETs remain a solid choice for cost-driven and lower-frequency designs. But GaN FETs offer high-frequency operation and size reduction. This makes it more practically usable for portable power devices. Using the GaN/Si choosing guide, you can make certain design decisions. As GaN fabrication scales in the future, the costs will drop and make it compete with silicon MOSFETs.