Advanced transistors (FinFET and GAA)

What is the state called in which the channel is so short that carriers travel from source to drain almost without scattering?

  1. ABallistic transport
  2. BDiffusive transport
  3. CHopping transport
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Answer: A. Ballistic transport

When the channel length becomes comparable to or shorter than the carriers' mean free path, carriers move from source to drain with almost no scattering by lattice vibrations or impurities. This is called ballistic transport, and the current is then set not by mobility but by factors such as the injection velocity from the source.

  • A. Correct. Carriers pass through without scattering.
  • B. Diffusive transport is ordinary conduction with repeated scattering.
  • C. Hopping transport is carriers jumping between localized states, seen in amorphous materials and the like.
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More Advanced transistors (FinFET and GAA) questions

  1. Which transistor has a source, channel and drain of the same conductivity type and doping, with no PN junctions?
  2. In FinFETs built on bulk substrates, what is the purpose of a heavily doped layer at the base of the fin (the part the gate controls poorly)?
  3. Which correctly describes the "scale length (natural length) λ" used to estimate the severity of short-channel effects?
  4. What is an effect of quantum confinement when fins or nanosheets are thinned to a few nanometers?
  5. In a FinFET made in the usual orientation on a (100) wafer, the fin sidewalls that form the channel are mainly (110) planes. What is the effect on mobility?