Abstract
Activation of the carbon buffer layer on 4H- and 6H-SiC substrates using elements with high magnetic moments may lead to novel graphene/SiC-based spintronic devices. In this work, we use a variety of surface analysis techniques to explore the intercalation of Er underneath the buffer layer showing evidence for the associated formation of quasi-free-standing graphene (QFSG). A combined analysis of low energy electron diffraction (LEED), atomic force microscopy (AFM), X-ray and ultraviolet photoemission spectroscopy (XPS and UPS), and metastable de-excitation spectroscopy (MDS) data reveals that annealing at temperatures up to 1073 K leads to deposited Er clustering at the surface. The data suggest that intercalation of Er occurs at 1273 K leading to the breaking of back-bonds between the carbon buffer layer and the underlying SiC substrate and the formation of QFSG. Further annealing at 1473 K does not lead to the desorption of Er atoms but does result in further graphitization of the surface.
Highlights
Graphene’s large spin relaxation length at room temperature continues to attract significant attention in terms of potential applications in spintronics.[1]
We explore the intercalation of Er underneath the carbon buffer layer that forms on 6H-SiC(0001) substrates using a variety of surface analysis techniques
Together with low energy electron diffraction (LEED), atomic force microscopy (AFM), and X-ray photoemission spectroscopy (XPS) results, the ultraviolet photoemission spectroscopy (UPS) and metastable de-excitation spectroscopy (MDS) data reveal that Er intercalates beneath the buffer layer, likely breaking back-bonds to form quasi-free-standing graphene” (QFSG) and thereby providing a potential system for future studies of spin-orbit coupling (SOC) enhancement
Summary
Graphene’s large spin relaxation length at room temperature continues to attract significant attention in terms of potential applications in spintronics.[1] Thermal decomposition of silicon carbide provides a route towards high-quality epitaxial graphene,[2] is limited for the 4H and 6H-SiC Si polar faces due to subsurface Si back-bonds These lead to the first carbon layer that forms having the same structure as graphene but acting as a buffer layer that displays no linear dispersion at the K-point in reciprocal space.[3] Adatoms such as H, Ca, Mn, Li, Au, Fe and Co4–10 have all been used to break these back-bonds, resulting in the formation of “quasi-free-standing graphene” (QFSG),[4] with the additional benefit of potentially enhancing the magnetic properties of this graphene layer.[10]. Together with low energy electron diffraction (LEED), atomic force microscopy (AFM), and X-ray photoemission spectroscopy (XPS) results, the UPS and MDS data reveal that Er intercalates beneath the buffer layer, likely breaking back-bonds to form QFSG and thereby providing a potential system for future studies of SOC enhancement
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call