More Foundries Eye GaN Market

Several foundry vendors are entering or expanding into the fast-growing gallium nitride (GaN) business.

By Mark LaPedus

Several foundry vendors are entering or expanding into the gallium nitride (GaN) business, a technology that is gaining steam in the automotive, computing, consumer and industrial markets.

Octric Semiconductors, Polar Semiconductor, X-Fab Silicon Foundries and Win Semiconductors are the latest foundry vendors to offer new GaN process technologies for customers. Foundry vendors manufacture chips for other companies in large facilities called fabs. Using a GaN process, a foundry vendor can manufacture various GaN-based chip-level devices. GaN-based devices can outperform traditional silicon-based chips in various specialized applications, such as power electronics, RF and others.

GaN, a III/V compound that combines gallium and nitrogen, is a wide bandgap (WBG) semiconductor material. “A ‘bandgap’ is the amount of energy needed to release electrons in semiconductor materials so that the electrons can move freely—allowing electricity to flow,” according to PowerAmerica, a U.S.-based power semiconductor consortium.

WBG semiconductors have bandgaps that are greater than traditional silicon-based chips. Silicon has a bandgap of 1.1 eV, while GaN is 3.4 eV. SiC has a bandgap of 3.3 eV. Gallium oxide (Ga0), which is in R&D, is 4.8 eV. (See chart below)

Devices based on WBG semiconductor materials can operate at higher voltages, frequencies and temperatures, as compared to conventional silicon-based chips. For example, in terms of switching speeds, GaN-based devices are faster than traditional silicon-based chips. Compared to silicon-based devices, GaN can withstand larger electric fields and can operate at higher temperatures. Plus, GaN can also enable the development of smaller and lighter products.

GaN itself isn’t new, as the technology first emerged in the 1960s. In 1972, the first GaN-based light-emitting diodes (LEDs) were developed. Then, in the mid-2000s, the first GaN-based transistors were commercialized.

Today, in the GaN market, suppliers sell various types of standalone chip-level products, including GaN-based field-effect transistors (FETs), GaN ICs, half bridge modules and others.

A transistor is one of the key building blocks in chips. A transistor is a tiny structure that amplifies or switches electrical signals in the device. A traditional silicon-based field-effect transistor (FET) is a lateral structure, which consists of a source, gate and drain. In operation, electric current flows between the source and drain in a channel. The current is controlled by a voltage applied to the gate.

Cross-sectional view of a MOSFET-type field-effect transistor, showing source, gate and drain terminals, and insulating oxide layer. Source: Wikipedia

Like a silicon-based FET, a GaN FET is also a lateral device with a source, gate and drain. The GaN FET operates like a traditional FET. But the GaN FET is partly made using various GaN materials. In the device, the current flows within a 2D electron gas channel (2DEG), which has a high charge density and mobility, according to TI.

There are two different types of GaN FETs: enhancement mode (e-GaN) and depletion mode (d-GaN). “An enhancement mode transistor is normally off and is turned on by positive voltage applied at the gate,” according to TI. “A depletion mode transistor is normally on and requires the use of negative voltage applied at the gate to turn off.”

Generally, in the marketplace, a GaN FET is sold as a standalone device, which is housed in an IC package. Meanwhile, a GaN integrated circuit (IC) combines a GaN FET, driver circuits and protection functions all on the same chip. Then, a half bridge module combines two GaN FETs and other functions all in the same package. Half bridge modules serve as the key basic building blocks in systems.

GaN, however, has some challenges. The lateral structure of GaN limits the technology to a narrow and limited set of voltage ranges. Generally, GaN-based power devices are used in 100- to 900-volt applications. Power Integrations, a supplier of power semiconductors, recently launched a 1700-volt GaN switch IC. In contrast, SiC-based power devices are used in 600-volt to 10-kilovolt applications.

Semiconductor characteristics of Si, SiC, GaN, and GaO Source: U.S. Department of Energy

GaN market-power electronics

The GaN market is a growing business, which can be split into two sub-segments: power electronics and RF. In the RF market, GaN devices are used in 5G wireless equipment, radar and other products.

Power electronics is a broad field, which deals with the control and conversion of electric power in systems. The electrical grid is one example. Appliances, cars, computers, smartphones and other products also make use of power electronics.

Take the simple phone charger for example. Not long ago, most phone chargers incorporated traditional silicon-based chips, which were used to help charge up a smartphone. But in general, it would take a long time to charge up a smartphone.

Then, several companies recently introduced so-called fast chargers. Instead of silicon-based chips, fast chargers incorporated GaN-based devices. With GaN, a fast charger can speed up the charging times by 3x, according to Navitas, a supplier of GaN- and SiC-based devices. Plus, a GaN-based fast charger is half the size and weight, according to Navitas.

According to the Yole Group, here are some of the other main applications for GaN in the power electronics space:

*Automotive-LiDAR systems for Advanced Driver Assistance Systems (ADAS)

*Data centers-power supplies

*Industrial--photovoltaics and aerospace

In total, the power GaN device market is expected to grow from $260 million in 2023 to $2.01 billion by 2029, a 41% growth rate, according to Yole.

Meanwhile, the power GaN ecosystem consists of integrated device manufacturers (IDMs), fabless design houses and foundry vendors. IDMs are companies that design and sell their own GaN-based devices in the market. These companies also manufacture their devices in their own fabs. Infineon, Innoscience, Nexperia, Rohm, Renesas, TI and others are IDMs in the power GaN space.

Fabless design houses design and sell GaN-based devices, but these companies do not own a fab. These companies have their GaN devices manufactured by foundry vendors. EPC, Navitas, Power Integrations and others are fabless design houses in the power GaN arena. GlobalFoundries, Vanguard, TSMC, X-Fab and others provide GaN foundry services in the power electronics arena.

New GaN foundry processes

Several foundry vendors are entering or expanding their efforts in the power GaN business. For example, X-Fab and IQE recently announced a joint development agreement to create a turnkey GaN power device platform solution. X-Fab and IQE will collaborate to develop a 650-volt GaN foundry process platform.

Belgium’s X-Fab, a specialty foundry vendor, offers a range of processes, such as analog/mixed-signal, MEMS and RF. X-Fab also offers GaN and SiC foundry services. U.K.-based IQE is a supplier of substrates.

X-Fab and IQE hope to solve a major problem in the GaN process flow. To make a GaN-based device in a fab, a device maker first obtains a 200mm substrate or wafer. The substrate is based on either silicon or SiC. Then, the device maker will deposit five thin layers of different GaN-based materials on top of the substrate.

Then, the device maker will take the substrate and subject it to various process steps in a fab. The goal is to develop a GaN FET on top of the substrate.

“In CMOS technologies, the raw wafers are a relatively simple commodity that can be easily interchanged between suppliers,” according to officials from X-Fab. “With GaN, the raw GaN wafer or substrate is a crucial part of the end processed wafer in terms of quality and performance. Typically, end customers have to qualify each combination of the substrate and the subsequent processing by X-Fab.”

That can be a time-consuming process. “In response, X-Fab and IQE are teaming up to offer a pre-qualified combination, so that end customers can proceed directly to the design,” according to officials from X-Fab.

Having a pre-qualified processed GaN substrate will enable fabless companies and others to speed up their product development times. "By combining our long-standing expertise in GaN device fabrication and design enablement with IQE’s epitaxy leadership, we are creating a unique, turnkey GaN power platform," said Jörg Doblask, chief technology officer at X-Fab.

In a separate move, Polar Semiconductor, a new U.S.-based foundry vendor, recently entered the GaN market. Polar licensed Renesas’ GaN-on-silicon technology. Polar will fabricate 650-volt GaN devices for Renesas and other customers in its 200mm fab in Minnesota.

“GaN is a game-changing technology for power and RF, and with Renesas as our partner, we are well-positioned to ramp commercial production, secure key defense programs, and drive the next wave of semiconductor innovation," said Surya Iyer, president and chief operating officer of Polar.

GaN market—RF

GaN is also used in the RF market. In the RF GaN market, suppliers also sell GaN FETs and related devices. These devices amplify a radio frequency (RF) signal in systems.

GaN is used in 5G equipment, defense electronics, satellite communications and other markets. In total, the RF GaN device market is expected to grow from $1.1 billion in 2023 to $2 billion by 2029, a 10% growth rate, according to Yole.

Suppliers of GaN-based RF devices include Macom, NXP, Qorvo, Sumitomo and others, according to Yole. BAE, GlobalFoundries, HRL, Macom, Win Semiconductors and others provide RF GaN foundry services.

Taiwan’s Win Semiconductors recently expanded its efforts in the RF GaN foundry segment by rolling out a new process.

Recently, the Ministry of Defense in the U.K. provided some funding for Octric Semiconductors, a new compound semiconductor foundry vendor. Located in Newton Aycliffe, U.K., Octric occupies a Class 100 manufacturing facility.

In 2024, the facility was acquired by the U.K. government from Coherent. The new company was renamed Octric. Octric is developing various technologies for foundry customers, including GaN, gallium arsenide (GaAs) and indium phosphide (InP).