16-10-2020 | | By Sam Brown
Recently, NXP announced its plan to upgrade its Arizona semiconductor foundry to produce 5G GaN semiconductor devices. What is GaN, how does it compare to silicon, and why is GaN a good candidate for 5G technologies?
GaN is a semiconductor crystal made from Gallium Nitride and has many properties that make it a real contender against silicon. GaN has a bandgap of 3.4eV, thermal conductivity of 1.3W/cmK, and electron mobility of 1500cm2/V.s. As a semiconductor, GaN has been used extensively in LEDs due to its ability to generate blue / violet light directly, and power applications due to its thermal and conductive properties.
When compared to Silicon, the industrial standard material for semiconductors, GaN has many advantages over silicon. To start, the electron mobility of GaN is 1,000 times greater than silicon, allowing for lower on-resistances, and thus better conductive losses. GaN is also able to operate faster than silicon devices, and there is speculation that GaN may be able to operate in the THz. The greater thermal conductivity allows for GaN devices to operate in more extreme conditions as they can readily remove heat, and the higher bandgap allows them to operate at greater voltages. Of course, GaN as a semiconductor technology is not as mature as silicon, and most foundries are geared towards silicon. Thus GaN devices are much more expensive. To understand the price difference, a 2-inch wafer of GaN costs $1,900, whereas a 6-inch silicon wafer costs between $25 to $50.
5G technologies are reliant on antenna systems that can deliver large amounts of power at radio frequencies. While GaN is expensive, 5G base stations can take advantage of GaN properties to produce radio communication systems that can operate at high powers, be thermally efficient, and able to operate at high frequencies. As base stations are rarely replaced, and the number of base stations pales in comparison to the number of mobile devices, using GaN at the base station provides a good compromise between cost and quantity for functionality. The use of GaN also allows for smaller systems, which can either lead to more discrete base stations or those that can integrate more complex systems per unit area.
Recognising the importance of GaN in future 5G networks, NXP has recently opened a new $100 million GaN foundry addition to their Chandler, Arizona factory. The new addition will allow for the production of 150mm GaN RF power amplifiers. According to NXP, the new site is the most advanced of its kind in the US and will help to produce state-of-the-art GaN devices.
Of course, NXP opening a GaN production facility is not only driven by the advantages of GaN in 5G networks; a report posted in march suggested that the GaN RF industry would grow from $17.4 billion (this year) to $26.6 billion by 2025. However, the urgency to produce 5G technology has now doubled down as a result of worldwide bans on Chinese equipment, which was to be the centre of 5G infrastructure. This has opened up opportunities for companies in the west to produce 5G equipment, and developing power-efficient RF amplifiers is one area that will especially benefit. Thus the initial $100 million investment (which was done before bans on Chinese equipment), was an exceptionally good move.