Description of the thesis topic

The The challenges of energy and reducing CO2 emissions are driving the demand for electronics that deliver ever-increasing power density and switching/conversion efficiency. These challenges have led to considerable developments in the field of large-gap semiconductor materials (SiC, GaN). These are the basic materials for medium-power electronics applications in the hybrid/electric car sector.
Beyond this power range - applications in the field of power distribution (smart grid) or transport (railways) - it is necessary to turn to less mature materials with band gap energies (more than 4 eV). The project involves a scientific challenge to study the physical properties of two oxides of potential interest for future electronics. Ga2O3, an oxide semiconductor with a large band gap (~5 eV) that can be easily doped to obtain n-type, whereas NiO can be p-type. The objective of the work is to produce epitaxial layers, to study their electronic properties in depth, mainly to identify point defects and to study the electrical conductivity mechanism in relation to other physical properties.
objective is to fabricate and study a vertical p-n diode based on a NiO/Ga2O3 heterostructure.
Activities
- Experimental study of Ga2O3 and NiOx thin films:
- Electrical contacts (Ohmic/Schottky) preparation: Photo lithography;
- RF-sputtering of thin films and metal electrodes;
- I-V characterization of electrical contacts versus temperature
- Hall effect, Resistivity measurements in temperature range [2K-850K]
- Photoconductivity, C-V measurement
- Optical transmittance/reflectance
- X-ray scans and analysis
- EPR spectroscopy
- Data analysis/interpretation
- Assisting in project management tasks: Preparation of scientific reporting and meeting organization
- Very strong involvement in scientific communication: consortium meetings/conferences/publications
- Training/knowledge sharing with other PhD and Master students

Required Skills
- Deep knowledge of physics of semiconductors: Electronic properties;
- Expertise in several of the following experimental techniques and instrumentations: Electrical contacts deposition/characterization; Electrical transport measurements (I-V; C-V; Hall Effect); EPR spectroscopy
- Chemical Vapor Deposition CVD, RF sputtering deposition
- Research experience related to wide band gap materials, oxides strongly appreciated
- French or/and English languages: oral and writing
- good communication skill
- Ability to respect deadlines and strong willing to share results/knowledge

Work Context

The work will take place at GEMaC Laboratory, which is a joint unit between the CNRS and Versailles-Saint-Quentin-en Yvelines University. GEMaC is also related with Paris-Saclay University. GEMaC is located in Versailles. The employer will be the CNRS.
Part of the experimental activity will be held at the INCSP laboratory in Paris, which is also a joint unit, between the CNRS and Paris Sorbonne University.
Also, the PhD student will have access to all necessary experimental facilities in GEMaC and INSP laboratories. The candidate will be in very tight relation with colleagues /teams working for the project and other foreign collaborators.

The position is located in a sector under the protection of scientific and technical potential (PPST), and therefore requires, in accordance with the regulations, that your arrival is authorized by the competent authority of the MESR.

Constraints and risks

The planned work will be very intense, with deadlines and multitasks.
The project including the objectives of the thesis program is labelled as of interest of national strategy. The position is located in a sector under the protection of scientific and technical potential (PPST). It requires that the arrival of the PhD student is authorized by the competent authority of the MESR, in accordance with the regulations.