Answer: ni² where ni is intrinsic carrier concentration.
- A n² alone, with little relation to the hole concentration
- B ni² where ni is intrinsic carrier concentration
- C n+p, the simple sum of electron and hole concentrations
- D Zero, as if electrons and holes rarely coexisted in the lattice
Correct answer: B. ni² where ni is intrinsic carrier concentration
Explanation: Mass action law: n × p = ni². This holds for both intrinsic and extrinsic semiconductors in thermal equilibrium.
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.