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HL: Fachverband Halbleiterphysik

HL 4: 2D Materials and their Heterostructures I (joint session DS/HL)

HL 4.10: Vortrag

Montag, 17. März 2025, 17:30–17:45, H3

The epitaxial growth of Gallium Selenide — Michele Bissolo, Marco Dembecki, Florian Rauscher, Jan Schabesberger, Abhilash Uhle, Jonathan J. Finley, Gregor Koblmüller, and •Eugenio Zallo — Walter Schottky Institut and TUM School of Natural Sciences, Technische Universität München, Garching, Germany

Group III-VI post-transition metal chalcogenides (PTMC, M={In,Ga} and C={S,Se,Te}) are van der Waals semiconductors with layer-dependent electronic, thermoelectric and optical properties, strong photoresponsivity, and a Caldera type valence band [1]. However, the limited scalability and risk of contamination of the standard mechanical exfoliation technique are detrimental to developing devices at an industrial scale. Here, we demonstrate the molecular beam epitaxy growth of PTMC [2] GaSe on 2-inch sapphire wafers. To study the pristine properties of this air-sensitive material in situ, we perform Raman spectroscopy in a UHV chamber directly connected to the growth chamber. Film composition and morphology are investigated by tuning the growth temperature and group VI/III flux ratio and by correlating them with the known spatial gradients across the whole substrate. The combination of these findings with ex-situ surface morphology characterization allows us to construct the phase diagram and identify the 2D layered region [3]. Perspectives on the growth of PTMC on 2D substrates and the epitaxial registry will be discussed. [1] H. Cai, et al., Appl. Phys. Rev. 6, 041312 (2019).[2] E. Zallo, et al., npj 2D Mater. & Appl. 7, 19 (2023).[3] M. Bissolo, et al., [to be submitted].

Keywords: 2D materials; epitaxy; gallium selenide; Raman; phase diagram