Exploring Physical Properties of Gallium Oxide Micro- and Nano-StructuresExploring light matter interaction in gallium oxide micro and nanostructures

This project aims to study physical properties in undoped and doped Ga2O3 micro- and nanostructures through the light-matter interaction, those involved in light generation, absorption, and propagation mechanisms inside the Ga2O3. These three features constitute the specific objectives of the project.For the synthesis of undoped and doped Ga2O3 and eventually ternary (AlxGa1-x)2O3 nanostructures with different architectures, the team used thermal evaporation methods with Chromium, Zinc and Germanium as dopants. The morphological and structural characterization of the obtained samples showed that the method is successful to create arbitrary features that are sufficient to generate the desired properties.Light generation of doped Ga2O3 under several injection beams (electrons, UV, visible light, and synchrotron X-ray) included time-resolved, polarized and temperature dependent measurements in some cases. The whole picture of the optical properties includes all recombination paths in the relaxation of excited carriers generated by the injected beams. Theoretical study of the electronic and vibrational states in undoped Ga2O3 and (AlxGa1-x)2O3 has been carried out by adopting the hybrid-exchange density functional, screened-exchange Heyd-Scuseria-Ernzerhof model. The role of defects, oxygen, and gallium vacancies, in the electronic structure has been assessed in the (AlxGa1-x)2O3 compound.Light absorption and transport phenomena. During the project, photoluminescence excitation spectra have been taken to determine the absorption which led to the main emissions of beta- and gamma- Ga2O3 nanoparticles. The work has allowed the team to determine the best protocol to achieve the electrical contacts and overcome some issues, such as early detachment of structures from substrates.Light confinement in undoped and Cr doped Ga2O3 nanostructures. During the project, DBR-based optical cavities have been built based on Ga2O3 microwires with hexagonal shaped cross-section.