Barrier inhomogeneities at vertically stacked graphene-based heterostructures

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Recent advancements in integrating atomically flat, two-dimensional materials like graphene.
• The critical need for understanding charge transport mechanisms in these novel heterostructures.

Purpose of the Study:

• To investigate the electron injection mechanism at the interface of vertically stacked graphene-based heterostructure transistors.
• To elucidate the temperature-dependent electrical characteristics of these devices.

Main Methods:

• Fabrication of vertically stacked graphene-based heterostructure transistors.
• Temperature-dependent electrical characterization from 300 K to 90 K.
• Analysis of current-voltage characteristics and Schottky barrier height.

Main Results:

• Observed an unusual decrease in effective Schottky barrier height with decreasing temperature.
• Noted an increase in the ideality factor as temperature decreased.
• Successfully modeled the conduction mechanism using thermionic emission with a Gaussian barrier distribution.

Conclusions:

• The study provides a precise interpretation of the electron conduction mechanism in graphene heterostructures.
• Mapping of the effective Schottky barrier height as a function of temperature and gate voltage was achieved.
• The findings offer significant insights for advancing layer-integration technology utilizing graphene-based heterostructures.