Disorder effects on energy bandgap and electronic transport in graphene-nanomesh-based structures

TL;DR

This study uses atomistic quantum simulations to explore how atomic edge disorder affects the energy gap and electronic transport in graphene nanomesh structures, revealing disorder's impact on device performance and experimental observations.

Contribution

It demonstrates that disorder reduces sensitivity of the energy gap to lattice symmetry and shows how GNM sections can improve device performance despite disorder effects.

Findings

Disorder suppresses the dependence of energy gap on lattice symmetry.

Finite GNM sections enhance electrical performance of devices.

Properly limiting GNM length mitigates disorder effects on transport.

Abstract

Using atomistic quantum simulation based on a tight binding model, we investigate the formation of energy gap Eg of graphene nanomesh (GNM) lattices and the transport characteristics of GNM-based electronic devices (single potential barrier structure and p-n junction) taking into account the atomic edge disorder of holes. We find that the sensitivity of Eg to the lattice symmetry (i.e., the lattice orientation and the hole shape) is significantly suppressed in the presence of the disorder. In the case of strong disorder, the dependence of Eg on the neck width is fitted well with the scaling rule observed in experiments [Liang et al., Nano Lett. 10, 2454 (2010)]. Considering the transport characteristics of GNM-based structures, we demonstrate that the use of finite GNM sections in the devices can efficiently improve their electrical performance (i.e., high ON/OFF current ratio, good current saturation and negative differential conductance behaviors). Additionally, if the length of GNM sections is appropriately limited, the detrimental effects of disorder on transport can be avoided to a large extent. Our study provides a good explanation of the available experimental data on GNM energy gap and should be helpful for further investigations of GNM-based devices.