Epitaxial growth

When a polar compound semiconductor such as GaAs is grown on a non-polar silicon substrate, what is the boundary called between regions in which the Ga and As positions are inverted?

  1. AAntiphase boundary (APB)
  2. BTwin boundary
  3. CGrain boundary
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Answer: A. Antiphase boundary (APB)

If the silicon surface has a single-atom step, regions with Ga and As positions swapped grow on either side, forming an antiphase boundary (APB) between them. APBs act as electrical defects, so countermeasures include using offcut substrates to obtain uniform double-atom steps.

  • A. Correct. It separates regions with inverted atomic arrangement.
  • B. A twin boundary separates crystals related by mirror symmetry.
  • C. A grain boundary separates grains with different crystal orientations.
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More Epitaxial growth questions

  1. In SiC epitaxy, what is the phenomenon called in which many atomic surface steps gather into large steps, roughening the surface?
  2. Which correctly describes epitaxial growth?
  3. Which is an example of heteroepitaxial growth?
  4. What is MOCVD (metal-organic chemical vapor deposition) mainly used for?
  5. What problem tends to occur when there is a large difference in lattice constant (lattice mismatch) between the substrate and the grown film?