Gold-free synthesis of hexagonal germanium

Hexagonal group IV materials like silicon and germanium are expected to display remarkable optoelectronic properties for future development of photonic technologies. However, the fabrication of hexagonal group IV semiconductors within the vapor-liquid-solid method has been obtained using gold as a catalyst thus far. We show the synthesis of hexagonal Ge on self-assisted GaAs nanowires using molecular beam epitaxy. With an accurate tuning of the Ga and As molecular beam flux we selected the crystal phase, cubic or hexagonal, of the GaAs NWs during the growth. A 500 nm-long hexagonal segment of Ge with high structural quality and without any visible defects is obtained, and we show that Ge keeps the crystal phase of the core using scanning transmission electron microscopy. Finally X-ray Photoelectron Spectroscopy reveals a strong incorporation of As in the Ge. This study demonstrates the first growth of hexagonal Ge in the Au-free approach, integrated on silicon substrate.

Contacts: José Penuelas,
Nicolas Chauvin,

Reference:
Hexagonal Ge Grown by Molecular Beam Epitaxy on Self-Assisted GaAs Nanowires
Iuliia Dudko, Thomas Dursap, Anne D. Lamirand, Claude Botella, Philippe Regreny, Alexandre Danescu, Solène Brottet, Matthieu Bugnet, Sumeet Walia, Nicolas Chauvin, and José Penuelas
Cryst. Growth Des. 2022, 22, 1, 32–-36
https://doi.org/10.1021/acs.cgd.1c00945

Collaboration:
Sumeet Walia – RMIT
Matthieu Bugnet – MATEIS

Acknowledgements
This work was supported by the LABEX iMUST (ANR-10-LABX-0064) of Université de Lyon, within the program “Investissements d’Avenir” (ANR-11-IDEX-0007) operated by the French National Research Agency (ANR).
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 801512.