The rise and rise of RF GaN

Thanks to the ever-reliable defence sector and buoyant telecom markets, the RF GaN market is poised for massive growth and will capture market share from LDMOS and GaAs soon, according to Compound Semiconductor Quarterly Market Monitor, Q3 2020 from Yole Développement (Yole).

ERRATUM: In connection with the publication in Q3 2020  of an article entitled “The rise and rise of RF GaN” which included a chart of RF GaN players, we have in September 2021 received a notification on behalf of Innoscience (Suzhou) Technology Co., Ltd of China (“Innoscience”), stating that,” while Innoscience is one of the major suppliers of GaN based products, it does not make, have made or offer for sale any product that is known to have been or will be used in any military application.
In concertation with Innoscience and consistent with our own findings as evidenced by our more recent reports, Yole Développement has taken the decision to update the publication entitled “The rise and rise of RF GaN”, by removing the name and logo of Innoscience from the original article dated November 26, 2020.

When it comes to compound semiconductors, few would argue that GaN is one of the key technologies to watch right now. Be it in military sectors, 5G telecom infrastructure or RF front end applications, the high power density and high efficiency material is making in-roads into many industry segments. And having shaken its reputation as an expensive semiconductor for very high-end applications only, rapid market adoption is predicted.

In 2019, Yole Développement valued the RF GaN device market at $740 million and forecasts this figure to reach beyond $2 billion by 2025. Along the way, GaN-on-SiC will seize market share from industry incumbents, silicon-based LDMOS and GaAs, in Defence, and Telecom and Infrastructure sectors.

Promising market developments are coming from NXP as well as industry partners, US-based II-VI Advanced Materials and Japanese Sumitomo Electric Devices Innovations. Both NXP and the II-VI/Sumitomo duo are building 6-inch GaN-on-SiC facilities in the US, opening the door to that all-important transition from 4- to 6-inch wafer fabrication, and the economies of scale this will bring.

Many eyes are also on less established GaN-on-silicon, which could yet gain a firm foothold in 5G telecom and 5G RF front end applications, thanks to its expandable wafer size, low cost and scalable silicon substrate supply chain. US-based Macom has teamed up with European STMicroelectronics, to develop the technology for telecom OEMs while France-based foundry, OMMIC, also offers GaN-on-silicon processes for mm-wave applications. Other industry players are working on GaN-on-silicon solutions for the exciting 5G handset RFFE applications, but operating in stealth-mode.

Still, nothing can beat GaN-on-Diamond when it comes to performance. Despite eye-watering costs, Diamond offers the highest thermal conductivity of any known material, making this technology ideal for high-end, high power applications including military radar and satellite communications. GaN and Diamond are not easy to bond but companies such as RFHIC, South Korea, and US-based Akash Systems are certainly making headway.

Crucially, the well-publicised US-China trade tensions are having a huge impact on market growth with China, the US and Europe bolstering domestic activities and building a more autonomous RF GaN supply chain to circumvent restrictions. Now the question is when will China become fully-autonomous? Similarly, the political situation has prompted all nations’ supply chains to evolve, setting the scene for a future, strong global market.

A key market for RF GaN has always been defence, with the largest growth, right now, coming from military radar applications including ground-based, airborne, space and ship-borne radar. The move from the old travelling wave tube (TWT) technology to solid-state Active Electronically Scanned Array (AESA) systems has delivered larger detection areas, faster scanning rates, higher spatial resolution and scalability.

These systems now contain thousands of transistors, and thanks to high power density, power-added efficiency and thermal conductivity, GaN-on-SiC can pack high performance into a light-weight, smaller footprint. Given this, the US Department of Defense (DoD) research arm, DARPA, has ploughed more and more cash into GaN for radar applications with industry heavyweights, such as Raytheon, Northrop Grumman and Lockheed Martin, also funding long-term programs.

Europe, Korea and China have followed the US lead, also setting up numerous GaN systems programs. And so GaN-on-SiC transistors and MMICs have progressively replaced LDMOS and GaAs devices.

However, GaN-on-SiC still remains relatively expensive compared to its competitors. Both LDMOS and GaAs transistors are fabricated on 6 inch wafers whilst GaN-on-SiC devices are predominantly produced on four inch wafers. What’s more, compared to silicon, SiC wafer manufacture is in its infancy with the industry’s limited number of SiC suppliers adding to the cost burden.

Still, no other technology looks set to deliver the power density and other advantages of GaN-on-SiC anytime soon, pointing to this being the technology of choice in AESA systems. Factor in growth from other key applications – electronic warfare and military communication – and Yole expects the GaN RF device market for this market segment to reach $1 billion by 2025, representing half of the anticipated market for the GaN RF device sector.

GaN first entered the telecom market in 2007 when used by Sumitomo for its 3G base stations. Huawei also integrated GaN into its 4G Long-Term Evolution (LTE) Remote Radiohead (RRH) base stations in 2014, reinforcing the technology’s deployment. And from here on in, more and more GaN RF devices have been adopted by telecom operators, keen to make the most of the technology’s high-power density and small form factor in antennas.

But while market growth has been typically driven by China-based OEMs, the move to 5G has prompted a rising number of infrastructure manufacturers, worldwide, to use GaN in RRH systems and more recently, Active Antenna Systems (AAS). While 4G networks operate at around 2.6 GHz, 5G networks will operate beyond 3 GHz frequencies, into the sub-6 GHz and even mm-wave regimes, spelling good news for GaN.

At 3 GHz frequencies and beyond, RRH base stations transmit at high power and demand very high power densities that only GaN can truly bring. As a result, more and more RRH system manufacturers are moving away from LDMOS and GaAs and towards GaN-on-SiC devices, with the technology set to dominate here.

Meanwhile, in the emerging segment of sub-6 GHz Active Antenna Systems, GaN and LDMOS rivalry is set to continue. While high power density is less of an issue, AAS infrastructure requires transistors that cover a large bandwidth of frequencies.

Cost-efficient LDMOS can still deliver high frequency performance here but GaN technology has the edge with its larger bandwidth, power-added efficiency and power output. Indeed, Yole anticipates GaN-on-SiC will gain more market share over time.

Small cells hold untapped potential with both GaN-on-SiC and GaN-on-silicon vying for market share alongside GaAs, SiGe, SOI and CMOS. Cost, wafer size and materials supply could prove to be bottlenecks for GaN compared to its rivals, but industry players are looking for new technologies in this market.

But what about our 5G handsets? Industry favourite, GaAs, is expected to retain its dominance within the handset for the next five years, as it still meets linearity and power requirements. Yet, in the race to save space in RF front-ends, GaN-on-silicon – with its high power density and high efficiency – offers interesting benefits for the handset power amplifier.

It’s also worth noting that at least one major company is working on GaN-on-silicon here, when a decade ago no-one would have believed that GaN would ever find its way into a mobile phone. In parallel, GaN-on-Si is also of great interest to myriad consumer and industrial applications, from RF cooking to automotive ignition.

Without a doubt GaN adoption is rising and fast. The technology is first destined for a growing number of applications in the defence industry and has a promising future in many commercial applications starting with 5G infrastructure, and perhaps eventually, the all-important handset. And while the US-tension China trade war has shaken up the RF GaN landscape, in the long-run, the strong domestic supply chains that will are currently being built will pave the way for a robust global market.

Authors

Ezgi Dogmus, PhD. is Team Lead Analyst in Compound Semiconductor & Emerging Substrates activity within the Power & Wireless Division at Yole Développement (Yole). She is managing the expansion of the technical expertise and the market know-how of the company.

In addition, Ezgi actively assists and supports the development of dedicated collection of market & technology reports, monitor as well as custom consulting projects.

Prior to Yole, Ezgi worked as a process development engineer for GaN-based RF and power solutions at IEMN (Lille, France). Ezgi has authored or co-authored more than twelve papers. After graduating from University of Augsburg (Germany) and Grenoble Institute of Technology (France), Ezgi received her PhD. in Microelectronics at IEMN (France).

Ahmed Ben Slimane, PhD. is a Technology & Market Analyst, specialized in Compound Semiconductors and Emerging Substrates at Yole Développement (Yole).

As part of the Power & Wireless team, Ahmed is contributing to the development of dedicated collection of compound semiconductors market & technology reports and monitor. Previously, he worked as an epitaxy (MBE/MOCVD) & fabrication process engineer for GaAs-based photovoltaic applications at TOTAL and IPVF (Paris-Saclay, France). Ahmed also completed his PhD in Material Engineering from KAUST (Saudi Arabia), where his mission was focused on GaN-based microstructures for flexible solid state lighting.

During his career, Ahmed Ben Slimane proposed lot of presentations towards an international audience. He authored/co-authored more than 20 publications in the semiconductor field and submitted a patent on the III-V hetero-structure for PV industry. Ahmed obtained his Master Degree in Electronics Engineering from INPG (Grenoble, FR).

Poshun Chiu is a Technology & Market Analyst specializing in Compound Semiconductor and Emerging Substrates at Yole Développement (Yole). As a member of the Power Electronics & Wireless division at Yole, Poshun focuses on power, RF, and opto-electronics. He is engaged in the development of technology and market reports and is also involved in custom projects.

Before joining Yole, Poshun had 9 years’ experience in R&D and product management at Epistar (TW & CHN). He is the author or co-author of more than 10 patents in solid-state-lighting. Poshun was also engaged in the development and evaluation of novel applications of process technology and components based on relevant semiconductor material systems

Poshun received an MSc degree in Microelectronics from National Cheng Kung University (TW) and an MBA from IESEG School of Business(FR).

Ezgi, Ahmed and Poshun are all part of the Compound Semiconductor & Emerging Substrates team, at Yole Développement.

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