Epitaxial growth

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?

  1. AElectromigration
  2. BSputtering
  3. COut-diffusion
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Answer: C. Out-diffusion

The high temperatures of epitaxy and later heat treatments make dopants from the heavily doped substrate diffuse through the solid into the epi layer, smoothing the concentration transition at the boundary. This is called out-diffusion, and it reduces the effective epi thickness. It is distinguished from autodoping, in which impurities are incorporated through the gas phase.

  • A. Electromigration is the movement of wiring metal atoms caused by current.
  • B. Sputtering is a deposition method that ejects atoms by ion bombardment.
  • C. Correct. Substrate dopants diffuse through the solid into the epi layer.
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More Epitaxial growth questions

  1. 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?
  2. 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.
  3. 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?
  4. 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?
  5. Which research-stage technique grows a crystal on a substrate covered with a 2D material such as graphene so that the grown film can be peeled off and the substrate reused?