The increase in electrical power density in everyday uses is the result of technological developments including materials and components. The first element to address is the use of a semiconductor material suitable for strong integration and capable of managing high power densities. Since the 2010s, wide bandgap semiconductors such as SiC or GaN have emerged in several applications and are causing a revolution in power electronics design, notably with an increase in the operating frequency and specific power of converters. Concerning Galium nitride (GaN), the increase in switching frequency was made possible thanks to the HEMT (High Electron Mobility Transistor). The idea of ??this PhD topic is to work on a HEMT GaN cell assembly. The work will involve the an assembly of two components through a common electrode on their backsides in order, making it possible to reduce parasitic inductances and increase the operating frequency. The work will be based on simulation tools such as COMSOL and Synopsys. The thesis will be in collaboration with the GEEPS laboratory at CentraleSupelec and the University of Paris-Saclay.