This chapter gives an overview of the current technologies for normally‐off GaN‐based high electron mobility transistors (HEMTs). First, the normally‐off HEMT “cascode” is briefly described. However, in power electronics applications, “true” normally‐off HEMTs are required. Hence, the most common technological solutions to obtain a positive threshold voltage are presented. In particular, after illustrating the recessed‐gate HEMT and the introduction of fluorine below the gate, the focus is placed on the recessed‐gate hybrid metal insulator semiconductor high electron mobility transistor (MISHEMT) and on the p‐GaN gate HEMT. These are currently the most promising and robust approaches for normally‐off GaN HEMTs. Finally, a few “nonconventional” routes proposed in the literature are also presented, although they are still very far from real applications.
Wiley‐VCH Verlag GmbH & Co. KGaA
15 Sep 2020
Nitride Semiconductor Technology: Power Electronics and Optoelectronic Devices