I found the following article informative. I copied some part of it below.
"One of GaN’s unique properties is its device physics properties, which enable it to perform in existing and new applications of wide-bandgap, high breakdown voltage, high power density, and high-gain performance. Using GaN for microwave devices provides 10 to 30 times more power and insulated gate advantages over competing technologies, such as silicon.
Although the GaN adoption rate has been slow in the RF realm, markets such as radar, military, and CATV have jumped to the forefront of using GaN. Another new opportunity in RF microwave applications beyond the high-power RF amplifiers includes RF switches used to create a more broadband switch. Using GaN technology for switches allows for low insertion loss, higher breakdown voltage, and higher-bandwidth switches. These switches can be used in automotive applications, such as hybrid vehicles, as well as solutions for energy conservation and power conversion. GaN also has received the industry’s green technology label because of its ability to provide lower product current consumption and improved thermal management while maintaining performance levels equal to or superior to competing semiconductor technologies. For example, today’s new CATV GaN-based amplifier products have lower current consumption and better linearity for improved video and data amplification compared to competing legacy technology solutions. This allows carriers to reduce the number of repeaters and driver amplifiers in their networks, further reducing the current consumption and operating costs of the overall network.
Other markets and applications are just beginning to explore GaN for new industries and devices. As with all emerging technologies, original, interesting applications continue to surface, such as the use of GaN in medical research. Recently, researchers discovered GaN is much different from other semiconductor materials in that it can be used safely in biomedical implants and it is nontoxic, which minimizes the risk to both the environment and the patient. This property alone leads scientists to believe this semiconductor material can be used for implants such as electrodes in neurostimulation therapies or for monitoring blood chemistry. Researchers also have created flexible GaN LEDs that can be implanted and used to detect various cancers, such as prostate cancer. These bio-integrated GaN devices have the potential for great innovations in the healthcare industry and hold the probability of expanding into unknown areas for GaN semiconductor designers.
Another of the largest and fastest-growing markets for GaN technology is the power management, or power conversion, industry. The advantage of using GaN in these applications is that GaN-based devices can be switched at high frequencies, well beyond current technology offerings, which means dramatic size reductions in passive components (such as transformers) and output filter components in power management and power conversion designs. Not only do GaN-based designs offer a five-time increase in switching frequencies, they also offer significant reductions of size and weight in the final product design. This reduction in weight and size generates benefits in automotive and UPS (uninterruptable power supply) applications, providing consumer benefits such as increased gas mileage in cars, increased office space, or building space in building or industrial settings."
http://www.rfglobalnet.com/doc.mvc/gan-the-technology-of-the-future-0001