Epitaxial growth

In MOCVD growth of GaN, what does the controlled condition "V/III ratio" mean?

  1. AThe ratio of film thickness to growth time
  2. BThe molar ratio of the group V source (such as ammonia) to the group III source (such as organogallium) supplied
  3. CThe ratio of growth temperature to pressure
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Answer: B. The molar ratio of the group V source (such as ammonia) to the group III source (such as organogallium) supplied

The V/III ratio is the ratio of the group V source to the group III source fed into the reactor. Because ammonia decomposes inefficiently, GaN growth uses very large V/III ratios of several thousand. The V/III ratio affects surface flatness, growth mode, impurity incorporation and more.

  • A. Thickness divided by time is the growth rate.
  • B. Correct. It is the supply ratio of group V to group III sources.
  • C. It is not the ratio of temperature to pressure.
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More Epitaxial growth questions

  1. When a lightly doped epi layer is grown at high temperature on a heavily doped substrate, what is the phenomenon called in which substrate dopants seep into the epi layer by solid-state diffusion, smoothing the concentration change at the interface?
  2. Which technique, developed by Isamu Akasaki, Hiroshi Amano and colleagues to grow high-quality GaN on sapphire, first deposits a thin layer at low temperature and then grows GaN at high temperature?
  3. In a lattice-mismatched system, which growth mode grows layer by layer for the first few atomic layers and switches to island growth as strain accumulates? It is also used to make quantum dots.
  4. When silicon is grown epitaxially on a substrate with patterns such as buried layers, what is the phenomenon called in which the steps appearing on the surface are offset from the underlying pattern or distorted in shape?
  5. What is the main purpose of epitaxially growing and embedding Si:C (silicon with a small amount of carbon) in the source and drain of nMOS transistors?