940-nm VCSELs grown by molecular beam epitaxy on Ge(001)

Karim Ben Saddik; Alexandre Arnoult; Pierre Gadras; Stéphane Calvez; Léo Bourdon; Richard Monflier; Wlodek Strupinski; Guilhem Almuneau

arXiv · 2603.11902

940-nm VCSELs grown by molecular beam epitaxy on Ge(001)

Karim Ben Saddik·Alexandre Arnoult·Pierre Gadras·Stéphane Calvez·Léo Bourdon·Richard Monflier·Wlodek Strupinski·Guilhem Almuneau

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Abstract

Vertical-cavity surface-emitting laser (VCSEL) structures emitting near 940 nm were grown by solid source molecular beam epitaxy (MBE) on Ge(001) substrates. The VCSEL MBE-growth was realized upon a virtual substrate composed of GaAs on Ge grown by melatorganic vapour phase epitaxy (MOVPE). In situ monitoring during MBE growth employed multispectral reflectometry and magnification-inferred curvature imaging for real-time growth analysis. Curvature measurements revealed progressive compressive stress, while optical reflectivity data confirmed uniform layer growth and accurate stopband formation. Fabricated devices with mesa diameters of 35-40 $\mu$m, corresponding to oxide apertures of approximately 11-16 $\mu$m, exhibited room-temperature lasing under continuous-wave bias with threshold currents below 3 mA. To the best of our knowledge, this is the first demonstration of monolithically integrated 940 nm VCSELs grown on Ge substrates by MBE. These results confirm the viability of MBE-grown VCSELs on Ge with in situ process control for scalable optoelectronic integration.

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Karim Ben Saddik, Alexandre Arnoult, Pierre Gadras, Stéphane Calvez, Léo Bourdon, Richard Monflier, Wlodek Strupinski, Guilhem Almuneau. 2026-03-12. 940-nm VCSELs grown by molecular beam epitaxy on Ge(001). https://arxiv.org/abs/2603.11902

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