Compound semiconductors

Which material, whose band gap can be tuned by composition, has been used for high-performance mid- to long-wave infrared detectors?

  1. AAl2O3
  2. BHgCdTe (mercury cadmium telluride)
  3. CSiO2
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Answer: B. HgCdTe (mercury cadmium telluride)

By changing the ratio of Hg to Cd, the band gap of HgCdTe can be tuned from almost zero to about 1.5 eV to match the infrared wavelength to be detected. It has been used in cooled, highly sensitive infrared detectors for astronomy, military and space applications.

  • A. Al2O3 (sapphire) is an insulator, not a light-absorbing material.
  • B. Correct. It is an infrared detector material with composition-tunable band gap.
  • C. SiO2 is an insulator, not an infrared detector material.
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More Compound semiconductors questions

  1. Which is one reason it is difficult to build silicon-like CMOS circuits in GaAs?
  2. How is silicon germanium (SiGe) classified?
  3. 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?
  4. What is the empirical rule called that says the lattice constant of an alloy semiconductor such as AlGaAs varies almost linearly with composition?
  5. 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?