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Research Highlight | Materials Science Division

Patterns in the atomic dance: coherent x-rays reveal interlayer correlations in islands during crystal growth

In a study published in Nature Physics, researchers pioneered, with the worldwide advent of new coherent X-ray sources, the experimental and analysis methods will enable broad application of XPCS to observe atomic-scale processes on surfaces.

Scientific Achievement

Using X-ray Photon Correlation Spectroscopy (XPCS), we observe correlations between arrangements of monolayer-height islands on succeeding layers during vapor phase epitaxy of GaN.

Significance and Impact

These first XPCS measurements of 2D island dynamics during layer-by-layer growth demonstrate the ability to observe fluctuation dynamics of weakly scattering surface features in operating and synthesis environments. 

Research Details

  • High-energy XPCS using high-intensity pink beam” was developed to enable in situ observation of atomic-scale surface dynamics.
  • Two-time correlations revealed persistence in arrangement of islands formed on each monolayer during crystal growth.
  • Kinetic Monte-Carlo modeling predicted conditions for persistence and identified atomic-scale mechanisms responsible.


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