At equilibrium condition, the rate of generation of electron-hole pairs in Ge crystal
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → equals the rate of recombination of electron and hole pairs
In a semiconductor, thermal energy keeps breaking covalent bonds and creating electron-hole pairs, while some free electrons keep falling back into holes (recombination). At equilibrium the number of carriers stays constant, which is possible only if the two processes go on at the same rate.
Option (3) equals the rate of recombination of electron and hole pairs — Correct. Equal rates keep the carrier concentration constant.
NCERT (2026-27):
Intrinsic Semiconductor – “… It may be noted that apart from the process of generation of conduction electrons and holes, a simultaneous process of recombination occurs in which the electrons recombine with the holes. At equilibrium, the rate of generation is equal to the rate of recombination of charge carriers. The recombination occurs due to an electron colliding with a hole.”