Consider an n-type semiconductor in which $n_e$ and $n_h$ are the numbers of electrons and holes, respectively.
(A) Holes are minority carriers
(B) The dopant is a pentavalent atom
(C) $n_en_h \ne n_i^2$
(D) $n_en_h \ge n_i^2$
(where $n_i$ is the number of electrons or holes in the semiconductor in its intrinsic form)
(E) The holes are not generated due to the donors
Choose the correct answer from the options given below:
Answer: (C) (A), (B), (E) only
- (A) In n-type material electrons are the majority carriers and holes the minority carriers ✔
- (B) n-type doping uses a pentavalent (group 15) impurity such as P or As ✔
- (C) In thermal equilibrium the mass-action law $n_en_h = n_i^2$ holds for doped semiconductors too, so (C) is false ✘
- (D) The product is fixed at exactly $n_i^2$; it is not a "greater than or equal" relation, so (D) is not the intended statement ✘
- (E) Donors give electrons only; the few holes come from thermal generation of electron–hole pairs ✔
Answer: (A), (B), (E) only.
Solution by Sreeraj P, M.Sc Physics