Question

What happens when $\mathrm{AgCl}$ is doped with ${\mathrm{CdCl}}_2$. What is the name of this defect?

Answer 1

Doping:

• The conductivity of these intrinsic semiconductors is too low to be of practical use. Their conductivity is increased by adding an appropriate amount of suitable impurity. This process is called doping.

Doping of $\mathrm{AgCl}$ with ${\mathrm{CdCl}}_2$:

• When $\mathrm{AgCl}$ is doped with ${\mathrm{CdCl}}_2$, cationic vacancies are created which means silver ion displaces from its position in the lattice due to the presence of neighboring cadmium ions.
• When $\mathrm{AgCl}$ is doped with ${\mathrm{CdCl}}_2$, $2$ silver ions $\left({\mathrm{Ag}}^{+}\right)$ are displaced by $1$ cadmium ion $\left({\mathrm{Cd}}^{2+}\right)$. Thus, one cadmium ion occupies the position of one silver ion.
• This type of vacancy is known as cationic vacancy.