Multi-scale electronics transport properties in non-ideal CVD graphene sheet

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Graphene's unique electronic properties are sensitive to structural imperfections.
• Surface corrugation and substrate interactions are common non-idealities in fabricated graphene devices.
• Understanding these variations is crucial for reliable graphene-based electronics.

Purpose of the Study:

• To benchmark the effects of structural non-idealities, specifically surface and in-plane corrugations, on graphene device performance.
• To investigate how random distortions influence electronic properties like density of states and charge distribution.
• To elucidate the impact of impurities on charge scattering in corrugated graphene.

Main Methods:

• Simulated over 200 graphene-based device structures using the non-equilibrium Green's function (NEGF) framework.
• Introduced random, inhomogeneous, and asymmetric corrugations (out-of-plane and in-plane) via autocorrelation functions.
• Examined variations in density of states, transmission modes, band structure, and charge densities, including impurity effects.

Main Results:

• Surface corrugation leads to increased variation in electronic and hole density distribution.
• Observed the formation of electron-hole charge puddles due to corrugation-induced symmetry breaking and quantum fluctuations.
• Simulated impurity effects to understand their impact on scattered charge distribution.

Conclusions:

• Structural non-idealities like corrugation significantly alter graphene's electronic landscape, creating localized charge puddles.
• The NEGF framework effectively models these effects, providing insights into device performance variations.
• Benchmarking various device morphologies and material compositions is essential for optimizing graphene electronic devices.