Epitaxial growth

Which correctly describes the critical thickness in heteroepitaxial growth?

  1. AThe minimum thickness needed for growth to start
  2. BThe maximum thickness that can be removed by etching
  3. CThe maximum thickness that can be grown while keeping its strain without generating dislocations
Show answer and explanation

Answer: C. The maximum thickness that can be grown while keeping its strain without generating dislocations

A film with a different lattice constant grows strained to match the substrate while it is thin (coherent growth). Once its thickness exceeds the critical thickness, misfit dislocations form to release the strain energy. This value is important when designing strained SiGe layers and similar structures.

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More Epitaxial growth questions

  1. What is the main purpose of heating the wafer in high-temperature hydrogen just before silicon epitaxial growth?
  2. Why are epitaxial layers important in the fabrication of SiC power devices?
  3. In epitaxial growth by CVD, the growth rate depends strongly on temperature in the relatively low-temperature regime. Why?
  4. Which is a typical crystal defect in epitaxial layers in which the stacking sequence of atomic planes is disrupted?
  5. In GaN and similar materials, what is the technique called that reduces dislocations by growing crystal from mask openings and then laterally over the mask?