CBSE Class 12 · 1999 · SemiconductorsVery Short Answer

A pure Si crystal having $5\times 10^{28}$ atoms ${\mathrm{m}}^{-3}$ is doped with 1 ppm concentration of antimony. If the concentration of holes in the doped crystal is found to be $4.5\times 10^9{\mathrm{m}}^{-3}$, the concentration (in ${\mathrm{m}}^{-3}$) of intrinsic charge carr …

(a) Explain the characteristics of a p-n junction diode that makes it suitable for its use as a rectifier.
(b) With the help of a circuit diagram, explain the working of a full wave rectifier.

Explain the following, giving reasons.
(a) A doped semiconductor is electrically neutral.
(b) In a p-n junction under equilibrium, there is no net current.
(c) In a diode, the reverse current is practically independent of the applied voltage.

In an extrinsic semiconductor, the number density of holes is $4\times 10^{20}{\mathrm{m}}^{-3}$. If the number density of intrinsic carriers is $1.2\times 10^{15}{\mathrm{m}}^{-3}$, the number density of electrons in it is

Pieces of copper and of silicon are initially at room temperature. Both are heated to temperature T. The conductivity of

The formation of depletion region in a p-n junction diode is due to