Next generation wireless network base stations, satellite communication systems and compact digital radar are just few examples where GaN-based devices can multiply the efficiency of amplifiers. However, improvements in GaN-based High Electron Mobility Transistors (HEMTs) are limited by the physics of already established AlGaN/GaN heterostructure system. ULTRAGAN project is aiming to explore new heterostructures using InAlN/(In)GaN alloys. The objective is to triple the HEMTs power density if compared to the state-of-the-art large periphery AlGaN/GaN HEMTs, InAlN/(In)GaN HEMTs are to demonstrate power densities of 30W/mm at 2 to 12 GHz.  These parameters can be achieved primarily because of expected extremely high 2-dimensional electron gas density coupled with polarisation fields in the InAlN/(In)GaN heterojunction. The project gives to Europe an opportunity to come back at the edge of the microwave research, which is right now much stronger in the USA. and Japan. Research teams from pure academia to industrial application laboratories will be combined to secure high efficiency research. Molecular Beam Epitaxy (MBE) and Metallorganic Chemical Vapour Deposition (MOCVD) techniques will be explored to develop devices including InAlN/GaN single heterojunction (SH) and InAlN /(In)GaN/(In,Al)GaN double heterojunction (DH) systems. Better confinement in the DH is a very attractive approach to limit the role of deep electrical levels by reducing electron  emission out of the channel. Moreover the chemistry of InAlN surface is expected to be different to GaN or AlGaN and more stable device surface might be discovered. A strong research will be carried out on the device passivation. In this way transistor I-V instabilities such as drain lags might be eliminated. The project also involves physical and thermal simulation, device processing and a full AC/DC HEMT characterization for a thorough device optimization. The Consortium team is composed of scientists from Austria, France, Germany, Greece, Slovakia and Switzerland.
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