If \( n_h \) is the number of holes per unit volume and \( n_e \) is the number of conduction electrons per unit volume in an extrinsic semiconductor. The relation between \( n_h, n_e \) and \( n_i \) is (\( n_i \), is intrinsic carrier concentration)
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \( n_i^2 = n_en_h \)
In thermal equilibrium, doping changes \( n_e \) and \( n_h \) individually, but their product stays fixed at the square of the intrinsic carrier concentration, because extra electrons increase the recombination of holes (and the reverse).
\( n_en_h = n_i^{2} \)
NCERT (2026-27):
Extrinsic Semiconductor – “… The electron and hole concentration in a semiconductor in thermal equilibrium is given by
\( \displaystyle n_e n_h = n_i^2 \qquad (14.5) \)”