The charge carries which have the greatest mobility are the _______.

Question

Question

This question was previously asked in

DFCCIL Executive (Electrical) Official Paper (Held On: 11 Nov, 2018 Shift 2)

Answer 1

Explanation:

Ions are immobile charges; So, they don't have any mobility
Electrons and holes are mobile charge carriers
The mobility of electrons is 2.5 to 3 times the mobility of holes
The mobility of electrons and holes depends on their effective masses.
The effective mass of electrons is less than that of holes hence electrons have higher mobility than holes.

Ge

Si

Electron mobility

\(3800\frac{{c{m^2}}}{{V - sec}}\)

\(1300\frac{{c{m^2}}}{{V - sec}}\)

Hole

mobility

\(1800\frac{{c{m^2}}}{{V - sec}}\)

\(500\frac{{c{m^2}}}{{V - sec}}\)

For \({\rm{Ge}} = \frac{{{\mu _e}}}{{{\mu _h}}} = \frac{{3800}}{{1800}} = 2.11\)

For \({\rm{Si}} = \frac{{{\mu _e}}}{{{\mu _h}}} = \frac{{1300}}{{500}} = 2.6\)

For both Ge & Si μe > 2μh