Unveiling the growth mode diagram of GaSe on sapphire

M. Bissolo; M. Dembecki; J. Belz; J. Schabesberger; M. Bergmann; P. Avdienko; F. Rauscher; A. S. Ulhe; H. Riedl; K. Volz; J. J. Finley; E. Zallo; G. Koblmüller

doi:10.1038/s43246-025-01005-9

arXiv · 2510.10743

Unveiling the growth mode diagram of GaSe on sapphire

M. Bissolo·M. Dembecki·J. Belz·J. Schabesberger·M. Bergmann·P. Avdienko·F. Rauscher·A. S. Ulhe·H. Riedl·K. Volz·J. J. Finley·E. Zallo·G. Koblmüller

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Abstract

The growth of two-dimensional epitaxial materials on industrially relevant substrates is critical for enabling their scalable synthesis and integration into next-generation technologies. Here we present a comprehensive study of the molecular beam epitaxial growth of gallium selenide on 2-inch c-plane sapphire substrates. Using in-situ reflection high-energy electron diffraction (RHEED), in-situ Raman spectroscopy, optical and scanning electron microscopies, we construct a diagram of the gallium selenide growth modes as a function of substrate temperature (530-650 °C) and Se/Ga flux ratio (5-110). The growth mode diagram reveals distinct regimes, including the growth of layered post-transition metal monochalcogenide GaSe with an unstrained in-plane lattice constant of 0.371$\pm$0.001 nm and a partial epitaxial alignment on sapphire. This work demonstrates a RHEED-based pathway for synthesizing gallium selenide of specific phase and morphology, and the construction of a phase diagram for high vapor pressure III-VI compounds that can be applied to a wide range of other metal chalcogenide materials.

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M. Bissolo, M. Dembecki, J. Belz, J. Schabesberger, M. Bergmann, P. Avdienko, F. Rauscher, A. S. Ulhe, H. Riedl, K. Volz, J. J. Finley, E. Zallo, G. Koblmüller. 2025-10-12. Unveiling the growth mode diagram of GaSe on sapphire. https://doi.org/10.1038/s43246-025-01005-9

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