Detecting the Major Charge-Carrier Scattering Mechanism in Graphene Antidot Lattices

TL;DR

This paper identifies pore-edge-trapped charges as the dominant charge-carrier scattering mechanism in graphene antidot lattices, revealing their potential for high-performance thermoelectric applications and heat management in electronics.

Contribution

It uncovers the energy-dependent scattering mechanism in GALs through Seebeck coefficient analysis, highlighting pore-edge-trapped charges as dominant, and demonstrates high thermoelectric power factors.

Findings

Pore-edge-trapped charges dominate scattering at elevated temperatures.

GALs achieve thermoelectric power factors up to 509 at 400 K.

High thermal conductivity and power factors make GALs suitable for active cooling.

Abstract

Charge carrier scattering is critical to the electrical properties of two-dimensional materials such as graphene, transition metal dichalcogenide monolayers, black phosphorene, and tellurene. Beyond pristine two-dimensional materials, further tailored properties can be achieved by nanoporous patterns such as nano- or atomic-scale pores (antidots) across the material. As one example, structure-dependent electrical/optical properties for graphene antidot lattices (GALs) have been studied in recent years. However, detailed charge carrier scattering mechanism is still not fully understood, which hinders the future improvement and potential applications of such metamaterials. In this paper, the energy sensitivity of charge-carrier scattering and thus the dominant scattering mechanisms are revealed for GALs by analyzing the maximum Seebeck coefficient with a tuned gate voltage and thus shifted Fermi levels. It shows that the scattering from pore-edge-trapped charges is dominant, especially at elevated temperatures. For thermoelectric interests, the gate-voltage-dependent power factor of different GAL samples are measured as high as 509 at 400 K for a GAL with the square pattern. Such a high power factor is improved by more than one order of magnitude from the values for the state-of-the-art bulk thermoelectric materials. With their high thermal conductivities and power factors, these GALs can be well suitable for "active coolers" within electronic devices, where heat generated at the hot spot can be removed with both passive heat conduction and active Peltier cooling.