PhD Defense of Roméo KOM KAMMEUGNE

This thesis presents a thorough analysis of the mechanisms controlling the GaN MIS-HEMT device performances through electrical characterization. To this end, a specific effort is made to understand how the devices work. First, new characterization methodologies of GaN MIS-HEMT transistors are developed. This allowed us to extract the intrinsic electrical parameters without source/drain access resistance effect, such as mobility and threshold voltage. The variability analysis of electrical parameter is also carried out. Then, a study is performed taking into consideration the specificities of GaN MIS-HEMT transistors with recessed gate in order to propose reliable characterization techniques, as well as their analytical modelling. This work is then improved by introducing a new mobility model which describes its decreasing with gate length and a new differential method that allows us to extract the electrical parameters on each active channel region. Finally, a thorough trap analysis in GaN MIS-HEMT devices is performed. This study allowed interface trap density extraction by different methods on the one hand and to the border traps evaluation in the gate oxide near the electron channel by low frequency (LF) noise measurements on the other hand. In this framework, a new complete noise model is developed for GaN MIS-HEMT devices with recessed gate. This enabled us to fit the LF noise parameters behaviour with gate lengths and to describe the impact of defects on the mobility.