The biden administration justified chip sanction with umbrella national security claim. While advanced chipmaking does have national security implication, it clearly does not have as much implication as Ga. I outlined in July Tweet why China is restricting Ga. Now that China has limited Ga export for about 3 months, time to revisit just how import Gallium is.
Ga is foundational to 2nd gen Semi Material GaA, which is widely used in 1st generation AESA radar, but has found wide adoption in fields like LED, laser diode and MMIC. Hard to have iPhones without GaA power amplifiers.
Ga is also foundational to 3rd gen Semi Material Gallium Nitride, which is now seeing wider adoption in AESA radar. GaN is more expensive than GaA, so it is normally grown on Sapphire, Silicon or Silicon Carbide substrate. The latter offers the most promising power amplifying returns as Wolfspeed explains here
Take a look below at GaA HEMT that’s commonly used for various RF applications, a lot of Gallium usage here across all the layers.
GaA is cheap, but has the limitations of 2nd generation semi material. just has lower breakdown field and bandgap than 3rd gen material like Silicon Carbide and Gallium Nitride. You just can’t use it for really high power applications
That’s where Gallium Nitride comes in. It is however a more expensive process, but uses less Ga since the substrate is something else (there is also GaN-on-GaN which is quite expensive). Here is a GaN HEMT (High electron mobility transistors) with AlGaN heterojunctions
While GaAs has a basic power density of about 1.5 W/mm, GaN has a power density ranging from 5 to 12 W/mm. From this article, GaN approximates 5x power density of GaA. It also has high electron mobility, making it ideal for HF operation & low noise. So you can use GaN HEMT across wide range of applications and get great performance. Making this ideal of defense industries. As you can see below, modern AESA radar have an assembly of TR modules, which are just MMIC with transmitters (power amplifiers) and receivers (low noise amplifiers)
Based on same article, current GaN process is 180nm tech for applications up to 20GHz. Next level tech is fully qualified for production just this year and is 140nm node and can be used for 50GHz due to shorter gate length & enhanced transistor performance.
The next GaN tech under development is 90nm HEMT process which allows it to be used in 75 to 110GHz (W-band frequencies). Similarly, GaA tech with 70nm gate length is being developed for low noise applications (likely LNAs) up to 100 GHz. This tech is very important for radar, missile seekers & SAR imaging.
The importance of GaN led America to block Chinese acquisitions of certain Western firms as early as 2015/16. None of that has really matter now since China has industrialized GaN production and able to deploy GaN AESA radars on weather radars and farming drones. You can buy 25W X band GaN TR modules on AliExpress for $5000 or military grade AESA radar for just 1m RMB
The industrialization & miniaturization of GaA and then GaN allowed PLAAF to be the first to deploy AESA radar missile seekers on PL-15. Nowadays when you walk across Chinese military shows, all the radar systems are using GaN modules. As early as 2018 Zhuhai airshow, producers of large UHF type of surveillance radar system claimed their radar can detect F-22s from 600km out.
China also may be ahead of America in GaN tech since leading Chinese firm supplying GaN modules to AESA radar reported (in IR related announcement) that it is in the process of developing W-band radar. That would imply it has already succeeded in miniaturizing GaN production to 90nm process and is not far away from producing this technology.
But GaN/AESA radar utility goes beyond that. As LT Gen Hinote said in this article, small miniaturized TR modules allow radar to emit different waves & pulses every time and also become really good at electromagnetic warfare. Being able to detect the other side and fool the other side about your presence is the basic foundation of modern air warfare
Having said this, is it a good idea for American govt to block China from Gallium Oxide and Diamond last year? Probably not, since China is the dominant producer of Ga and artificial diamond! Just a few month later, China produced its first 8-inch Gallium Oxide wafer. All of this just ended up reducing Ga supply that American industries need to access in order stay competitive in RF.
Today, Ga is quite essential in various 5G RF front end components like Power Amplifiers. Cannot build power amplifier modules without PAs. LNAs often made with SiGe or GaA also. If companies like Qorvo, Qualcomm see vastly reduced supply of Ga/Ge in the market, it could potentially impact their RFFE business.
Typo here: “how import Gallium is”