1 research outputs found
Mid-Infrared Mapping of Four-Layer Graphene Polytypes Using Near-Field Microscopy
The mid-infrared
(MIR) spectral region attracts attention for accurate
chemical analysis using photonic devices. Few-layer graphene (FLG)
polytypes are promising platforms, due to their broad absorption in
this range and gate-tunable optical properties. Among these polytypes,
the noncentrosymmetric ABCB/ACAB structure is particularly interesting,
due to its intrinsic bandgap (8.8 meV) and internal polarization.
In this study, we utilize scattering-scanning near-field microscopy
to measure the optical response of all three tetralayer graphene polytypes
in the 8.5–11.5 μm range. We employ a finite dipole model
to compare these results to the calculated optical conductivity for
each polytype obtained from a tight-binding model. Our findings reveal
a significant discrepancy in the MIR optical conductivity response
of graphene between the different polytypes than what the tight-binding
model suggests. This observation implies an increased potential for
utilizing the distinct tetralayer polytypes in photonic devices operating
within the MIR range for chemical sensing and infrared imaging