Novel GaN-based transistors using polarization engineering

For more than 20 years, the field of group III nitrides has been among the most exciting ones in solid-state device research. During this time, significant progress has been obtained not only from a technological point of view, but also and more importantly in terms of understanding these materials and their very specific properties.This paper gives a summary on our results on the growth of heterostructures based on quaternary barriers, the compositional control and the implications on crystal and electrical properties. The additional degree of freedom acquired by this capability is applied to a variety of device designs such as normally-off or high-ns structures with excellent transport properties. Finally, the formation of polarization-induced two-dimensional hole gases (2DHGs) in inverted heterostructures is demonstrated.