Compound semiconductors

Which is one reason it is difficult to build silicon-like CMOS circuits in GaAs?

  1. ABecause GaAs hole mobility is very low compared with electron mobility, making high-performance p-channel transistors hard to build
  2. BBecause GaAs electron mobility is too low
  3. CBecause GaAs does not absorb light
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Answer: A. Because GaAs hole mobility is very low compared with electron mobility, making high-performance p-channel transistors hard to build

GaAs has higher electron mobility than silicon but low hole mobility, so the gap between electrons and holes is very large. CMOS needs n-channel and p-channel transistors of comparable performance, so high-performance CMOS is hard to build in GaAs. The difficulty of forming a good gate insulator is another reason.

  • A. Correct. Low hole mobility makes p-channel devices weak.
  • B. GaAs is notable for electron mobility higher than silicon's.
  • C. GaAs is a direct-gap semiconductor that absorbs light well.
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More Compound semiconductors questions

  1. How is silicon germanium (SiGe) classified?
  2. What is a high-frequency IC called that integrates transistors together with passive components such as inductors and capacitors on a substrate such as GaAs?
  3. What is the empirical rule called that says the lattice constant of an alloy semiconductor such as AlGaAs varies almost linearly with composition?
  4. Which configuration combines a normally-on GaN HEMT in series with a low-voltage silicon MOSFET so it can be used safely with normally-off behavior?
  5. When a strong field is applied to GaAs, electrons transfer to another valley with lower mobility, and negative differential resistance appears in which current decreases as the field rises. Which oscillator device uses this?