Comparing the magnetotransport and Raman response of various intercalants in epitaxial graphene on 6H-SiC(0001)*

Intercalation is a common way to modify the electronic properties of graphene. For instance, hydrogen intercalation results in p-type graphene, whereas magnesium intercalated graphene results in highly n-type doped graphene (≈1E14 cm^-2) with large bandgap (≈0.36 eV) [1][2]. Epitaxial graphene on 6H-SiC(0001) ('Gr/SiC') consists of the SiC substrate, the carbon rich ‘buffer layer’ which is partially bonded to the SiC surface, and the graphene on top.  Over the past decade, Gr/SiC has been intercalated with numerous elements. Typically, the intercalant is confined to the region between the buffer layer and the SiC surface, and is able to release the buffer layer from the SiC to form another layer of graphene.

In this talk, we present results on the magnetotransport of hydrogen intercalated Gr/SiC at low temperatures (0.3 K – 50 K) and high magnetic fields (12 T), and compare these results to both as-grown and magnesium intercalated graphene. We observe multiple Shubnikov de Haas (SdH) oscillations, even in a sample with large dimensions (4 mm²). Moreover, our (vanadium doped) semi-insulating SiC substrates do not result in any observable hysteresis of our magnetoresistance.

In addition to our magnetotransport results, we compare the Raman response for as-grown and magnesium intercalated Gr/SiC. We find a significant shift in the location of the 6H-SiC(0001) Raman peaks in the range 100 – 1000 cm^-1, suggesting the presence of a highly n-type doped SiC surface upon intercalation.  

[1] Kotsakidis, J. C., et al. Chemistry of Materials 32.15 (2020): 6464-6482.

[2] Grubišic-Cabo, A., et al. Applied Surface Science 541 (2021): 148612.