The End of Silicon? Explaining the Hype Around Gallium Nitride (GaN)
For decades, “silicon” has been a by-word for high-technology and advanced electronics. Silicon Valley‘s didn‘t get its name for nothing, and few materials have been so widely studied and invested in. However, recently there has been a lot of talk about a new semiconductor that outperforms silicon in almost every way. That material is gallium nitride (GaN), and if you believe the hype, silicon‘s time at the top could be coming to an end.
We‘ve touched on GaN in the past when discussing our groundbreaking Omnia series of chargers, but in this article, we‘ll take a closer look at the material itself, and discuss whether it really does have the potential to unseat silicon from its throne.
How does GaN Compare to Silicon?
One of the key attributes of GaN as a semiconductor is its wide band gap of 3.4eV, compared to 1.14eV for silicon. Band gap is a complicated concept to explain, but put simply, such a wide band gap allows GaN to handle much higher voltages and temperatures than silicon.
The other key stat is that GaN has 1000 times better electron mobility than silicon, allowing for much faster current flow and greatly reduced heat and energy dissipation (i.e. less waste).
Put these two together and you have a material that‘s extremely efficient and highly capable in scenarios that involve a lot of power or heat.
Applications
The earliest application of GaN in consumer products was in LEDs and other optoelectronics such as lasers. It has also been used in radar systems, radio transistors, and has promising potential in microwave ovens and electric vehicles (EVs). Aside from being well suited to high power situations, the material also handles high frequencies very well. This trait makes it ideal for use in 5G base stations, particularly those that use ultra-high-frequency millimeter wave signals (>24 GHz).
Ideal for Chargers
However, the mostly widely publicized use of GaN in consumer technology is in wall chargers. In many ways, this is an ideal application for this material because it makes full use of its key strengths. A GaN power IC (integrated circuit) is able to handle significantly more power than a silicon power IC of the same size. In practical terms, this means you can have a 60W GaN charger that‘s the same size and weight as a 30W silicon charger. The exact reduction in size and weight varies depending on the specific product, but a 50% reduction is typical of the Omnia series compared to Apple‘s chargers of the same power, and some models offer even greater reductions (the Omnia 61W is fully 65% smaller and lighter than Apple‘s 61W MacBook charger). It also means there‘s space to fit more in ports or other features without bloating the charger to an impractical size. As an example, the Omnia Duo 65W has two fast-charging USB-C ports, but is still around 50% smaller than Apple‘s single port 61W model.
In recent years, phone charging has been getting much more powerful, with some devices supporting 60W and above through various technologies. The trouble with these ultra-high-powered chargers though is that they can get very, very hot. Aside from being a bit inconvenient and potentially a bit alarming, these hot chargers are also very wasteful. GaN circuitry is much more suitable for high-powered chargers like this, although many of the big players in the industry have been slow to adapt. Not only is GaN much more resilient to high power and temperatures, the faster current flow greatly reduces heat dissipation, meaning the charger is less likely to feel hot to the touch.
A Revolution Coming in Wireless Charging?
So far, the main application of GaN in charging tech is in traditional wall chargers, but there‘s a lot of excitement what GaN could do for wireless charging. Even more so than wall chargers, wireless chargers are often hampered by thermal limitations, and these problems are only going to become more acute as wireless charging gets more powerful (25W wireless charging is already on the market). Even 15W wireless chargers require fans and extensive ducting, so the superior thermal performance of GaN will surely bring major benefits here. What‘s exciting about GaN is that we‘re currently nowhere near reaching the limits of what the material is capable of, while silicon is extremely well-understood and there isn‘t much room left for further progress. In five years‘ time, it‘s likely GaN will be turning up in places not yet conceived of.
Are Silicon‘s Days Numbered?
The main drawback cited for GaN compared to silicon is that generally it‘s a bit more expensive. However, it should be pointed out that this isn‘t because it‘s a fundamentally more expensive material. Rather, it‘s mainly down to economies of scale and silicon production being far more widespread. Also, an important advantage of GaN compared to other alternative semiconductors is that it can be produced in the same facilities as silicon with little additional work required. In the short-term, the low price of silicon means it‘s likely to remain the semiconductor of choice in scenarios where GaN‘s strengths don‘t really come into play (e.g. basic electronics).
However, as GaN becomes more widespread (5G-related demand is expected to be huge), economies of scale will start to build up and the price will come down. Moore‘s law (stating that computing power doubles roughly every 18 months) has held up for decades as semiconductor manufacturers were able to shrink silicon chips down to improbable sizes. However, there must surely come a point when silicon development reaches its limit and a new material is required for a breakthrough. In such a scenario, it seems plausible that GaN could find itself at the core of much of the tech we use.
Currently, the main barrier to this are a few technical drawbacks to GaN in how it operates in a logical circuit (GaN transistors are always the “normally on” type, while silicon can be either “normally on” or “normally off”). However, there are numerous proposals on how to get round this, and there‘s a lot of positivity from researchers that with a few modifications, GaN could be a silicon-beater across the board.
For now though, it‘s enough to marvel at the amazingly tiny chargers GaN has brought us, and it‘s exciting to imagine what the future could hold.
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