Electron backscatter diffraction study of hexagonal boron nitride growth on Cu single-crystal substrates
Jennifer K Hite1, Zachary R Robinson1, Charles R Eddy1
1†U.S. Naval Research Laboratory, Washington, D.C. 20375, United States.
ACS Applied Materials & Interfaces
|June 20, 2015
Summary
Substrate orientation significantly impacts hexagonal boron nitride (h-BN) growth. Researchers found that lower surface free energy of copper (Cu) substrates, like Cu(111), promotes greater h-BN coverage, crucial for 2D heterostructures.
Area of Science:
- Materials Science
- Surface Science
- Nanotechnology
Background:
- Hexagonal boron nitride (h-BN) is a key material for advanced 2D heterostructures.
- Understanding the influence of substrate crystallography on h-BN growth is essential for controlling heterostructure fabrication.
- Previous studies have not fully elucidated the direct correlation between specific copper (Cu) crystallographic orientations and h-BN growth characteristics.
Purpose of the Study:
- To investigate the effect of different copper (Cu) substrate orientations on the growth and coverage of thin hexagonal boron nitride (h-BN) films.
- To establish a relationship between the crystallographic structure of Cu substrates and the resulting h-BN film morphology and coverage.
- To determine how substrate surface free energy influences h-BN growth kinetics.
Main Methods:
- Simultaneous growth of h-BN on various Cu substrate orientations: polycrystalline Cu foil, Cu(100), Cu(110), and Cu(111).
- Characterization techniques included Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS) for h-BN identification.
- X-ray photoelectron spectroscopy (XPS) for effective thickness, scanning electron microscopy (SEM) for morphology, and electron backscatter diffraction (EBSD) for Cu substrate crystal structure analysis.
Main Results:
- h-BN growth rate was inversely proportional to the surface free energy of the Cu substrate.
- Cu(111) substrates exhibited the highest h-BN surface coverage due to their lowest surface free energy.
- Polycrystalline Cu foil, predominantly oriented as (100), showed h-BN film coverage comparable to that on a pure Cu(100) substrate.
Conclusions:
- The crystallographic orientation of the Cu substrate is a critical factor determining h-BN film coverage and growth habit.
- Surface free energy plays a significant role in controlling h-BN growth kinetics on metallic substrates.
- These findings provide crucial insights for optimizing h-BN growth conditions in the fabrication of 2D heterostructures.
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