Fujitsu Limited and Fujitsu Laboratories Ltd. announced that they have developed a crystal structure that both increases current and voltage in gallium-nitride (GaN)(1) high electron mobility transistors (HEMT)(2), effectively tripling the output power of transistors used for transmitters in the microwave band. The GaN HEMT technology can serve as a power amplifier for equipment such as weather radar, by applying the developed technology to this area, it is expected that the observation range of the radar will be expanded by 2.3 times, enabling early detection of cumulonimbus clouds that can develop into torrential rainstorms.
Fujitsu and Fujitsu Laboratories have now developed a crystal structure that improves operating voltage by dispersing the applied voltage to the transistor, and thereby prevents crystal damage (patent pending). This technology has enabled Fujitsu to successfully achieve the world’s highest power density at 19.9 watts per millimeter of gate width for GaN HEMT employing indium-aluminum-gallium nitride (InAlGaN) barrier layer.
In recent years, GaN HEMTs have been widely used as high-frequency power amplifiers in long-distance radio wave applications, such as radars and wireless communications. It is also expected that they will be used for weather radars to accurately observe localized torrential rainfall, as well as in millimeter-waveband wireless communications for fifth-generation mobile communications (5G). The outreach of microwaves from the microwave and millimeter-wave bands used for radar and wireless communications can be extended by increasing the output power of the high-frequency GaN HEMT power amplifiers used for transmitter. This allows for expanded radar observation range as well as longer distance and higher capacity communications.
Fujitsu Laboratories has been conducting research on GaN HEMTs since the early 2000’s, and currently provides the aluminum-gallium nitride (AlGaN) HEMTs used in a variety of areas(3). Recently, Fujitsu Laboratories has been conducting research on indium-aluminum-gallium nitride (InAlGaN) HEMTs as a new generation GaN HEMT technology, which enables high current operation as high-density electrons become available. Accordingly, Fujitsu and Fujitsu Laboratories have developed a crystal structure that achieves both high current and high voltage simultaneously.