Dopant segregation in polycrystalline monolayer graphene

Area of Science:

• Materials Science
• Solid-State Chemistry
• Nanotechnology

Background:

• Dopant concentration heterogeneity significantly influences the electronic properties of chemically doped materials.
• Understanding dopant distribution is crucial for designing advanced functional materials.

Purpose of the Study:

• To experimentally investigate the distribution of substitutional nitrogen atoms during chemical vapor deposition.
• To determine if dopant atoms segregate at crystal grain boundaries or distribute uniformly.

Main Methods:

• Chemical Vapor Deposition (CVD) for material synthesis.
• Microscopic analysis to observe dopant distribution at grain boundaries and within grains.
• Experimental variation of growth parameters (temperature, pressure, substrate, precursor).

Main Results:

• Substitutional nitrogen atoms demonstrably avoid crystal grain boundaries and edges on micron length scales.
• Nitrogen dopants exhibit uniform distribution within the interior of individual grains.
• This phenomenon was consistently observed across various growth conditions, indicating universality.

Conclusions:

• The spatial distribution of dopants is not solely dictated by growth parameters but also by crystallographic features like grain boundaries.
• Uniform dopant distribution within grains, away from boundaries, offers new possibilities for controlling electronic properties in doped semiconductors.
• This research provides fundamental insights into dopant behavior during CVD, relevant for semiconductor manufacturing and materials design.