Experimental Studies of Graphene Antidot Lattices for Thermoelectric Applications*

Pristine graphene has low thermoelectric performance due to its ultra-high thermal conductivity and zero band gap that leads to a low Seebeck coefficient ($S)$. Both issues can be addressed by patterning periodic nano- or sub-1-nm pores (antidots) across graphene, called graphene antidot lattices (GALs). In GALs, a geometry-dependent band gap can be opened up to dramatically increase S, with significantly reduced thermal conductivity ($k)$ due to phonon scattering by antidots. Above will lead to a high thermoelectric figure of merit (\textasciitilde 1.0 at 300 K by computations [1]) in GALs to be used for device cooling. Despite numerous calculations, experimental studies of GALs are restricted to electrical conductivity ($\sigma )$ measurements for GALs with \textasciitilde 10 nm patterns. The critical k measurements are still lacking. In this work, all three thermoelectric properties ($S$, $k$, and $\sigma )$ are measured on suspended GALs with sub-10 nm pores. In comparison, electrical properties are also characterized for GALs on a substrate. The results presented here provide important guidance on how to tailor transport properties of general two-dimensional materials with ALs. References: [1] Yan et al., Physics Letters A 376, 2425-2429 (2012).