Question

n-type semi-conductor is one in which …….. .

(A) the number of electrons > the number of holes

(B) the number of holes > the number of electrons

(C) the number of holes = the number of electrons

(D) none of these​

Answer 1

n-type semi-conductor is one in which the number of electrons > the number of holes.

Answer:

Option A is right

Explanation:

SEMI CONDUCTORS:

• Semi conductors are those that do not show conductivity at normal state, but on after certain treatment shows conductivity to a narrow range.

• Group 14 elements are called semi conductors. They have four electrons in their valence shell.

• The gap between valence band and conduction is small and can be overcome by heating or by adding impurities.

• Depending upon the type of imuprity added, the semiconductor may be n type or p type semiconductor. This is called doping.

n TYPE SEMICONDUCTOR:

• When pentavalent imuprity is added to semi conductors, they are called n type semi conductors.

• Four electrons can occupy the valence site in semi conductor and one electron remains free.

• That one electron is responsible for producing current due to its motion.

• Number of electrons is greater than the number of holes.

• Though the semi conductor has free electrons, it is electrically neutral.

p TYPE SEMICONDUCTOR:

• When trivalent imuprity is added to semi conductors, they are called p type semi conductors.

• Three electrons can occupy the valence site in semi conductor. This creates a hole with no electron in it.

• Electron from the adjacent atom jumps into the hole. Again a vacancy is created in that atom.

• This movement of holes indirectly is responsible for conductivity.

• Number of holes is greater than the number of electrons .

• Though the semi conductor lacks an electron, it is electrically neutral.