Answer: exp(-E g /2kT) (via mid-gap traps).
- A exp(-E<sub>g</sub>/kT), the simple intrinsic-carrier exponential with little factor of two
- B exp(-E<sub>g</sub>/2kT) (via mid-gap traps)
- C ni² × exp(V/2VT), an expression with an incorrect forward-bias-like voltage term
- D 1/T, a simple inverse-temperature dependence with little exponential
Correct answer: B. exp(-E<sub>g</sub>/2kT) (via mid-gap traps)
Explanation: G-R current ~ ni (not ni²), scales as exp(-Eg/2kT). Dominant reverse current in wide-bandgap semiconductors at low temperature.
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.