Seminare Marielena VELASCO-ENRIQUEZ 02.06.2026

Chemical pathways to obtain Ga₂O₃ films for next generation power electronics and optoelectronics

PhD candidate, Marielena VELASCO-ENRIQUEZ
 

 Université Grenoble Alpes, CNRS, Grenoble INP, LMGP, Grenoble F-38000, France

Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, Grenoble F-38000, France

Abstract

Ultrawide bandgap semiconductors like β-Ga2O3 are promising candidates for power electronics and optoelectronics thanks to their large bandgap energy (4.6 – 4.9 eV), high breakdown electric field (~8 MV/cm), broadband photodetection, and availability of high-quality substrates.[1] Beyond the thermodynamically stable β-Ga2O3, metastable polymorphs (α, γ, δ, κ) may offer additional functionalities, including piezoelectricity (κ-phase).[2]

This work explores two different chemical approaches in vapor phase and aqueous solution to grow Ga₂O₃ thin films and microstructures on c-plane sapphire substrates. First, pulsed-liquid injection MOCVD (PLI-MOCVD), that unlike conventional MOCVD systems, enables fine control over precursor delivery and dosing, improving chemical yield and reducing gallium waste, an important sustainability consideration.[3] Second, chemical bath deposition (CBD) followed by thermal annealing that offers a low-cost, tunable pathway to obtain crystalline Ga₂O₃,[4] though the link between growth parameters and final properties remains poorly understood.

By adapting and systematically investigating both methods, the impact of key parameters on morphology, structure, chemistry, and optical properties using a broad range of characterization techniques (SEM, XRD, TEM, XPS, Raman, UV-Vis, cathodoluminescence, etc.) is studied. This comparative approach provides insight into the assets and limitations of each technique for controlled Ga₂O₃ synthesis.

[1]        J. Y. Tsao et al., “Ultrawide-Bandgap Semiconductors: Research Opportunities and Challenges,” Advanced Electronic Materials, vol. 4, no. 1, p. 1600501, 2018, doi: 10.1002/aelm.201600501.

[2]        M. Bosi, P. Mazzolini, L. Seravalli, and R. Fornari, “Ga 2 O 3 polymorphs: tailoring the epitaxial growth conditions,” Journal of Materials Chemistry C, vol. 8, no. 32, pp. 10975–10992, 2020, doi: 10.1039/D0TC02743J.

[3]        H. Guillon and S. Bonnafous, “Vaporization of Solid or Liquid Organic, Organometallic or Inorganic Compounds,” no. Gases&Instrumentation, pp. 17–19, Jun. 2008.

[4]        G. Hector et al., “Chemical Synthesis of β-Ga2O3 Microrods on Silicon and Its Dependence on the Gallium Nitrate Concentration,” Inorg. Chem., vol. 59, no. 21, pp. 15696–15706, Nov. 2020, doi: 10.1021/acs.inorgchem.0c02069.

Short Bio/CV

Originally from the Amazonian region of Peru. I earned my Bachelor’s in Engineering physics at Universidad Nacional de Ingeniería in Lima, Peru. After conducting research in Peru and abroad on soft robotics, plasma physics, and material science, I moved into industry as an R&D Engineer in the automotive sector, designing and testing eGlasses. Three years later, I pursued the Erasmus Mundus Master in Nanoscience and Nanotechnology, specializing in nanoelectronics at KU Leuven (Belgium) and TU Dresden (Germany). Since 2023, I have been a PhD candidate at Université Grenoble Alpes, working across LMGP and Institut Néel as part of the cross-disciplinary program PowerAlps from.