Question

(a) What change occurs when $AgCl$ is doped with $CdC{l}_2$?
(b) What type of semiconductor is produced when silicon is doped with boron?

Answer 1

a. When AgCl is doped with $CdC{l}_2$ a cationic vacancy is created, i.e., an $A{g}^{+}$ ion from the lattice is absent from its position due to presence of adjacent $C{d}^{++}$ .

When AgCl is doped with $CdC{l}_2$, two $A{g}^{+}$ ions are replaced by 1 $C{d}^{2+}$ ion. So, where one $C{d}^{2+}$ ion occupies the site of one $A{g}^{+}$ ion, there is a cationic vacancy.

b. p-type semiconductor

The addition of trivalent impurities such as boron, aluminum or gallium to an intrinsic semiconductor creates deficiencies of valence electrons,called "holes". It is typical to use $B_2{H}_6$ diborane gas to diffuse boron into the silicon material.