Sujet de thèse : « Fabrication And Caracterisation Of GaN Power Diodes And Transistors For DC-DC Voltage Converter »

This thesis work fits into a need of integrability of energy conversion circuit with high power density. The temperature tolerance and conduction properties of GaN devices enable high electrical efficiency and a significant volume decrease of embedded systems. The target application is the DC-DC voltage conversion, and the primary active devices fabrication processes for making a switching cell – an AlGaN/GaN High Electron Mobility Transistor (HEMT) and a field-effect rectifier diode – are the main goal. A power charge supply until a kilowatt is waiting.
The first technological lock in the HEMT development is to plan a specific process allowing its normally-off (enhancement mode) behavior, that is essential for a security need in this purpose.
Therefore, the main part of this work aims to find out a stable fluorinated plasma treatment of the AlGaN surface layer.The second challenge is the realization of a low power consumption field-effect rectifier. The process-controlled channel pinch-off lets avoid the basic constraints of the GaN Schottky diode, by reducing the on state-voltage threshold, the reverse leakage current and the anode capacitance.