Graphene quality indicators obtained by Raman spectroscopy have been correlated to the structural changes of the graphene/Germanium interface as a function of in-vacuum thermal annealing. Specifically, it is found that graphene becomes markedly defected at 650 {\deg}C. By combining scanning tunneling microscopy, x-Ray Photoelectron Spectroscopy and Near Edge x-ray Absorption Fine Structure Spectroscopy, we conclude that these defects are due to the release of H_{2} gas trapped at the graphene/Germanium interface. The H_{2} gas was produced following the transition from the as-grown hydrogen-termination of the Ge(110) surface to the emergence of surface reconstructions in the substrate. Interestingly, a complete self-healing process is observed in graphene upon annealing to 800 {\deg}C. The subtle interplay revealed between the microscopic changes occurring at the graphene/Germanium interface and graphene's defect density is valuable for advancing graphene growth, controlled 2D-3D heterogeneous materials interfacing and integrated fabrication technology on semiconductors.
@article{arxiv.2204.02037,
title = {Tracking interfacial changes of graphene/Ge(110) during in-vacuum annealing},
author = {L. Camilli and M. Galbiati and L. Di Gaspare and M. De Seta and I. Píš and F. Bondino and A. Caporale and V. -P. Veigang-Radulescu and S. Hofmann and A. Sodo and R. Gunnella and L. Persichetti},
journal= {arXiv preprint arXiv:2204.02037},
year = {2022}
}