Tracking interfacial changes of graphene/Ge(110) during in-vacuum annealing

TL;DR

This study investigates how in-vacuum annealing affects the interface between graphene and Ge(110), revealing defect formation due to trapped H₂ gas release and subsequent self-healing at higher temperatures, with implications for material integration.

Contribution

It provides detailed insights into the microscopic interfacial changes during annealing, linking Raman spectroscopy indicators to structural transformations and defect dynamics.

Findings

Graphene becomes defected at 650°C due to H₂ release.

Self-healing of graphene occurs at 800°C.

Interfacial changes influence defect density and material quality.

Abstract

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.