Answer: Electrons spatially separated from ionized dopants, reducing Coulomb scattering.
- A A higher concentration of dopant atoms is introduced near the channel
- B Electrons spatially separated from ionized dopants, reducing Coulomb scattering
- C The device is simply operated at a lower temperature with no spatial effect
- D A thicker semiconductor layer is used in the heterostructure
Correct answer: B. Electrons spatially separated from ionized dopants, reducing Coulomb scattering
Explanation: 2DEG in HEMT: ionized donors in wide-gap layer, electrons accumulate in narrow-gap layer. Spatial separation reduces impurity scattering. Ultra-high mobility.
Conductors have overlapping bands, semiconductors have a small energy gap that can be bridged by heat or doping, and insulators have a large gap that blocks conduction.
Concept context
Band theory, p-n junction, diodes, transistors, logic gates, and integrated circuits.