GaN high electron mobility transistors (HEMT) are becoming the mainstream for high frequency and power switching applications. Devices and circuits based on these emerging materials are more suited to operate at higher voltages and temperatures than Si-based devices owing to their superior physical properties. In this presentation, I will show the current status of III-Nitride based technologies for RF and power applications that have been developed within the nanofabrication center of IEMN in France through partnerships with industrials. In particular, the evolution of the promising approach based on GaN HEMTs with Al-rich ultrathin barriers for future millimeter-wave applications will be described. Furthermore, I will discuss some potential solutions that we are pursuing with the aim of pushing the limits and address new requirements of high voltage power devices. In this frame, various device designs and preliminary results of novel GaN-on-Silicon vertical transistors and AlGaN-channel Ultra-Wide Band Gap lateral devices will be presented.