Topic: Suppression of rotational domain formation during heteroepitaxial growth of Ga₂O₃ by the metalorganic chemical vapour deposition (MOCVD)
Supervisor: : Ing. Filip Gucmann, PhD. (Department of III-V Semiconductors)
Co-advisor: Ing. Michal Blaho, PhD.
Description: Almost one third of all produced electricity passes through power electronic devices at some stage before consumption with the predicted increase up to 80 % for the next decade. Therefore, even small efficiency improvement of power electronics represents significant energy savings and reduction of carbon emissions. One of the ways to achieve higher efficiency of power electronic devices is the use of new (ultra) wide bandgap (Eg) semiconductor materials. Gallium oxide (Ga2O3) is a good example of such material – with Eg ~4.9 eV and high critical field which surpasses those of the mainstream semiconductors for power switching in the range up to several kVs (Si, SiC, GaN). Ga2O3-based devices can be also invaluable for faster deployment of electric means of transport thanks to development of faster charging systems and more efficient energy transfer between batteries and electric drivetrain. It can also significantly contribute to improve efficiency of power conversion generated by renewable sources (solar, wind).
The main objective of this thesis will be the investigation and optimisation of epitaxial growth of thin Ga₂O₃ layers, and related materials such as (AlₓGa₁₋ₓ)₂O₃, on foreign substrates (Al₂O₃, SiC, Si) using metal–organic chemical vapor deposition (MOCVD). A particular emphasis will be on suppressing the formation of rotational domains associated with the substrate surface symmetry. The formation of rotational domains currently represents a major research challenge, as their presence severely degrades the structural, thermal, and transport properties of heteroepitaxial Ga₂O₃ layers and prevents the full exploitation of the material’s potential in power electronic devices.
Epitaxial growth will be carried out using a commercial Aixtron MOCVD growth system with a vertical CCS reactor, as well as an experimental MOCVD reactor employing liquid precursor injection. Furthermore, advanced technological equipment and processes available at the Institute of Electrical Engineering of the Slovak Academy of Sciences (IEE SAS), will be used. PhD candidate will acquire a broad range of experimental skills in materials diagnostics (e.g., X-ray diffraction, atomic force microscopy, Raman spectroscopy, and advanced electrical characterization methods). The work will be conducted within a joint collaboration project with the Taiwanese partner ITRI (Industrial Technology Research Institute).