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Vertical versus Lateral Two-Dimensional Heterostructures: On the Topic of Atomically Abrupt p/n-Junctions
Ruiping Zhou1, Vaibhav Ostwal1, Joerg Appenzeller1
1Birck Nanotechnology Center and ‡Department of Electrical and Computer Engineering, Purdue University , West Lafayette, Indiana 47907, United States.
Nano Letters
|July 19, 2017
Summary
Two-dimensional (2D) heterostructures show reduced rectification ratios. Reported p/n-junctions in 2D materials are explained by Schottky barrier effects in lateral transport, not ideal vertical junctions.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Two-dimensional (2D) materials like graphene offer unique electronic properties due to their atomic thinness.
- These materials enable novel device architectures, including heterostructures formed by stacking dissimilar 2D layers.
- Recent studies report strong diode-like rectification in 2D heterostructures with sharp p/n-junctions.
Purpose of the Study:
- To investigate the rectification properties of truly vertical 2D heterostructures.
- To re-evaluate the interpretation of reported p/n-junction behavior in 2D heterostructures.
- To explain the observed rectification within established physical frameworks.
Main Methods:
- Fabrication and characterization of vertical 2D heterostructures.
- Electrical transport measurements under varying gate and drain voltages.
- Modeling of charge transport considering Schottky barrier effects.
Main Results:
- Truly vertical 2D heterostructures exhibit significantly lower rectification ratios than previously reported.
- The strong rectification observed in prior studies is attributed to lateral transport effects.
- Schottky barriers at the interfaces play a crucial role in the observed electronic behavior.
Conclusions:
- The concept of atomically sharp p/n-junctions in vertical 2D heterostructures needs re-evaluation.
- Schottky barrier physics adequately explains the rectification phenomena in these systems.
- Future device designs should account for lateral transport and Schottky barrier contributions.
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