Description du sujet de thèse

To overcome the multiple challenges of the energy transition, whether in the generation, transmission or use of electricity, highly efficient electronic components are needed. The replacement of incandescent light bulbs with light-emitting diodes (LEDs) is a notable example of the value of new components for lighting made from materials such as those in the gallium nitride (GaN) family. Today, other components are being developed from this material to make fast switches and rectifiers that can withstand high voltages at reduced component sizes compared to those made from silicon. However, all these components, which should reduce energy losses during all stages of electricity transformation, remain difficult to manufacture in large quantities at low cost. Whether for domestic applications below 220 V, or for electric or hybrid vehicles between 600 and 1200 V, epitaxial deposition of semiconductors such as GaN on large diameter substrates is a key point to lower manufacturing costs. For this purpose, Silicon substrates are used as a carrier, but the large differences in crystalline properties (lattice parameters, thermal expansion coefficients) between GaN and Silicon are at the origin of crystalline defects and mechanical stresses that are detrimental to the controlled manufacture of high-performance components. To overcome this point, an original treatment is being developed to make the Silicon substrate compliant during the epitaxy phase of the GaN material.
This development, which is currently funded by the French National Research Agency (ANR), is being carried out in partnership with the LN2 laboratory of the University of Sherbrooke (Canada), the GREMAN (Tours), CRHEA (Valbonne) and GREYC (Cherbourg) laboratories. GREMAN is in charge of the fabrication of the porous silicon substrates. The structures of the components will be epitaxied at CRHEA. Transistors and LEDs will be manufactured respectively at LN2 and CRHEA. All the laboratories will participate in the various characterizations.
To carry out this work, he/she will need to have knowledge in materials science or solid-state physics. Experience in Raman spectroscopy would be appreciated.

Contexte de travail

The thesis will take place in the two laboratories CRHEA and GREYC. The candidate recruited for this project will participate at CRHEA in the development of epitaxy and in the study of the structural properties of epitaxial semiconductor layers. At GREYC, he (she) will study the thermal properties of the materials and the behavior of LED and power transistor components fabricated on these compliant substrates.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.