Defect Control and n-Doping of Encapsulated Graphene by Helium-Ion-Beam Irradiation

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Graphene and hexagonal boron nitride (h-BN) are advanced 2D materials with unique electronic properties.
• Understanding and controlling defects in 2D materials is crucial for their technological applications.
• Ion bombardment is a common method to induce defects for material modification.

Purpose of the Study:

• To investigate the impact of helium ion (He(+)) bombardment on graphene encapsulated in h-BN.
• To study the environmental influences on beam-induced defects in this heterostructure.
• To elucidate the mechanisms behind defect behavior and doping in h-BN encapsulated graphene.

Main Methods:

• Raman spectroscopy was employed to analyze beam-induced defects.
• Electrical measurements were conducted to assess the electronic properties of the graphene.
• Comparative analysis of defect peak behavior (D and D' peaks) under varying conditions.

Main Results:

• The D' defect Raman peak exhibits environmental sensitivity, unlike the D defect peak.
• The D' defect peak saturates with increasing ion dose in encapsulated graphene.
• Electrical measurements confirmed n-type conduction in the hexagonal boron nitride-encapsulated graphene.
• Evidence of self-healing of lattice damage and n-doping due to nitrogen-carbon exchange was observed.

Conclusions:

• Unbound atoms at the graphene-h-BN interface facilitate self-healing of ion-induced lattice damage.
• Nitrogen-carbon exchange at the interface is responsible for the observed n-doping of graphene.
• The distinct environmental sensitivity of the D' defect peak offers insights into defect dynamics in 2D heterostructures.