Answer: Narrower bandgap material (lower conduction band minimum).
- A Wider bandgap material, which has a higher conduction band minimum
- B Narrower bandgap material (lower conduction band minimum)
- C Whichever side happens to be doped p-type, regardless of bandgap
- D Whichever side happens to be doped n-type, regardless of bandgap
Correct answer: B. Narrower bandgap material (lower conduction band minimum)
Explanation: Type-I heterojunction (straddled gap): both conduction and valence band offsets confine carriers to narrower bandgap material. Used in quantum well lasers.
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.