GaN technology aiding power supply miniaturisation

The development of GaN (Gallium Nitride)-based electronic devices is allowing for the construction of more compact, lighter and cheaper power converters. And in the coming years, growth in the GaN semiconductor device market is expected to have a major effect on power supply miniaturisation.

According to a recent report, the GaN power semiconductor device market will achieve a CAGR of 4.6 percent between 2017 and 2023 to reach $22.47 billion by 2023, from $16.50 billion. The key drivers include the vast consumer electronics and automotive market with optoelectronic devices holding the largest market share.

However, GaN devices will also have success in innovative military, defence and aerospace applications. This summer, Northrop Grumman delivered the first US Marine Corps (USMC) AN/TPS-80 Ground/Air Task Oriented Radar (G/ATOR) fitted with GaN radar technology. It is designed to replace five ageing and legacy radars. All subsequent G/ATOR production systems will now incorporate GaN. The full rate production programme is scheduled to begin in early 2019.

It is though the market for GaN-based power drives, which is expected to grow significantly to 2023, that is attracting much attention. This is due to features such as minimum power loss, high-speed switching miniaturisation, and high breakdown voltage as compared with silicon-based power devices.

There is a substantial market for GaN in power distribution, industrial and heavy electrical systems and turbines, as well as heavy machinery, advanced industrial control systems, and electromechanical computing/computer systems. GaN is also finding applications in several of the new power applications, such as high-voltage direct current (HVDC), smart grid power systems, wind turbines, wind power systems, solar power systems, and electric and hybrid electric vehicles (EVs).

Figure 1: A GaN switch is built on a silicon substrate, with a lateral two-dimensional electron gas (2DEG) channel formed on a AlGaN/GaN hetero-epitaxy structure that provides very high charge density and mobility; the enhancement-mode GaN device does not conduct when the gate drive is at zero (left image) but does conduct when the gate drive exceeds the threshold (center and right images). (Source: GaN Systems). Click to enlarge

Earlier this year, Panasonic announced that it had developed a Metal Insulator Semiconductor (MIS) GaN power transistor, capable of continuous stable operation with no variation in its threshold voltage. This unveiling followed extensive research carried out by the company into MIS gate structure as a future technology to further increase operation speed.

Panasonic had been already mass-producing GaN power transistors, known as gate injection transistor (GIT) on silicon (Si) substrates. But this new MIS type GaN power transistor will achieve higher-speed operation than the GIT offering. The newly developed GaN power transistors have continuous stable operation at a maximum gate voltage of +10V. They also operate at high current and voltages (drain current of 20A and breakdown voltage of 730V). The high-speed switching features an ‘OFF’ operation time of 1.9ns and ‘ON’ operation time of 4.1ns.

Meanwhile, in July AIXTRON SE the Aachen, Germany headquartered manufacturer of deposition equipment for the semiconductor industry announced that it will provide New York Headquartered NexGen Power Systems Inc. with high-quality MOCVD (metalorganic chemical vapour deposition) technology for the further development of GaN-based electronic devices. As of the third quarter of this year, it is supplying NexGen with its AIX G5 HT planetary system.

Both in terms of yield and operating costs, AIXTRON claims that the AIX G5 HT is the current standard for “all advanced GaN applications.” Dinesh Ramanathan, CEO of NexGen Power Systems, said, "Our disruptive True GaN ™ VJFET4 technology is capable of silicon, silicon carbide or GaN-on silicon technology with higher breakdown voltage, lower on-resistance and higher switching frequency...We look forward to supporting NexGen's efforts to revolutionize existing power converters."

And at the 2018 electronic symposium held in Philadelphia in June, the US successor company to RF Micro Devices, which designed and manufactured high-performance radio frequency systems and solutions for wireless and broadband communications, unveiled new products for GaN and 5G. Among the offerings were two new ultra-compact GaN X-band front-end modules (FEMs): the QPM2637 and QPM1002.

Both provide four functions in a single compact package, including an RF switch, power amplifier, low noise amplifier and limiter. They can withstand up to 4 W of input power on the receive side without permanent damage. This is a vast improvement over a typical GaAs LNA, which can be damaged by less than 100 mW of input power.

Other developments include the announcement in August by Fujitsu Limited and Fujitsu Laboratories Ltd. of a crystal structure that both increases current and voltage in GaN high electron mobility transistors (HEMT). This effectively triples the output power of transistors used for transmitters in the microwave band and has enabled Fujitsu to achieve the world’s highest power density at 19.9 watts per millimetre of gate width for GaN HEMT. Details of the technology were announced at the August 5-10 International Symposium on Growth of III-Nitrides (ISGN-7), held in Warsaw.

It is clear that the market for technologies and materials such as GaN, which support electronic product miniaturisation, are set to grow. Power converters play a key role in almost all electronic devices, from home appliances to data centres, laptops and electric cars. And the development of GaN semiconductor devices, modules and systems is playing a key role by increasing the efficiency and reliability of power converters while significantly reducing their cost, size and weight.

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