PerspectiveMaterials Science

Epitaxial Growth Writ Large

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Science  22 Jan 2010:
Vol. 327, Issue 5964, pp. 423-424
DOI: 10.1126/science.1184947

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Summary

The performance of semiconductors in device applications often depends on their crystallinity—the grain boundaries and defects of a polycrystalline material interfere with transport of charge carriers. Single crystalline layers can be grown through epitaxy: Atoms are deposited from the gas phase on top of an existing crystal to form new layers. However, if the growth process is not well controlled or is too rapid, unwanted surface features, such as mounds, may form. Thus, the fabrication process relies heavily on monocrystalline growth of a single element. Models to find optimal conditions for this process have been studied for a long time (1, 2) and have had to become increasingly sophisticated (3, 4). Insights from related processes involving molecules or even larger particles can test our understanding of how epitaxy works and can be easier to observe directly. On page 445 of this issue, Ganapathy et al. (5) describe epitaxial growth with colloidal spheres some four orders of magnitude larger than atoms. Models developed for atomic epitaxy can describe these processes, despite colloid-colloid attractions arising in a way very different from atomic interactions.