Semiconductors | MCQs Quiz-02

If the energy of a photon of sodium light (λ=589 nm) equals the band gap of a semiconductor, then the minimum energy required to create a hole-electron pair is-

Assertion- In insulators, the forbidden gap is very large.
Reason- The valence electrons in an atom of an insulator are very tightly bound to the nucleus.

Assertion- An n-type semiconductor has a large number of electrons but still it is electrically neutral.
Reason- An n-type semiconductor is obtained by doping an intrinsic semiconductor with a pentavalent impurity.

A p-type semiconductor is-

(i) a silicon crystal doped with arsenic impurity
(ii) a silicon crystal doped with aluminium impurity
(iii) a germanium crystal doped with boron impurity
(iv) a germanium crystal doped with phosphorus impurity

In an extrinsic semiconductor, the number density of holes is 4 x 10²⁰ m^-3. If the number density of intrinsic carriers is 1.2 x 10¹⁵ m^-3, the number density of electrons in it is-

A. 1.8 x 10⁹ m^-3

B. 2.4 x 10¹⁰ m^-3

C. 3.6 x 10⁹ m^-3

D. 3.2 x 10¹⁰ m^-3