PhD Defense of Jonathan LEHMANN

Tuesday, October 20, 2015 at 10h30

Abstract :
This PhD is part of the development of HEMT power transistor based on gallium nitride at the CEA. Due to their high electron mobility, high breakdown field and good thermal conductivity, AlGaN/GaN HEMT  are very promising devices for power electronic applications. The goal of this PhD is, using electrical characterization,  to increase the knowledge of the AlGaN/GaN material prior to the fabrication of transistors.

First, through measurements of the resistance of the electron gas located at the AlGaN/GaN interface, a trapping phenomenon was evidenced in the material. Then, in order to set a production follow-through of AlGaN/GaN on Si wafers , a method of measuring the sheet resistance of a AlGaN/GaN stack without the fabrication of contacts was developed and patented. Finally, on HEMT transistors fabricated using different epitaxies, a detailed study of the sheet resistance, the mobility and the sheet carrier density in and out of the gated area was carried out.

Keywords:
HEMT, AlGaN/GaN, electrical characterization


Members of the jury :
Edwige BANO - Professor IMEP-LAHC : Supervisor
Gérard GHIBAUDO - Research supervisor IMEP-LAHC : Co-supervisor
Charles LEROUX - Engineer , CEA-LETI : Co-supervisor
Dominique PLANSON - Professor INSA Lyon : Chairman
Jean-Guy TARTARIN - Professor LAAS-CNRS : Rapporteur
Nathalie LABAT - Professor IMS : Rapporteur