Question

Silicon doped with gallium forms

• A. P-type semiconductor
• B. N-type semiconductor
• C. Both n and p type semiconductor
• D. an intrinsic semiconductor

Answer 1

The Correct Option is A

When silicon (Si), which has 4 valence electrons, is doped with gallium (Ga), which has 3 valence electrons, it creates a p-type semiconductor. This occurs because gallium has one fewer valence electron than silicon, creating a "hole" in the crystal structure where an electron is absent. This hole acts as a positive charge carrier, making the material a p-type semiconductor. Thus, silicon doped with gallium forms a p-type semiconductor, which corresponds to option (A).

The correct option is(A) : P-type semiconductor

Answer 2

When silicon is doped with gallium, gallium (a trivalent element) replaces some of the silicon atoms in the crystal lattice. Gallium has three valence electrons, while silicon has four. When gallium is introduced into the silicon structure, it creates a "hole" (a missing electron) because there are fewer electrons in the bonding orbitals than needed for full bonding.

These "holes" act as positive charge carriers. Since the charge carriers are positive, the material formed is a p-type semiconductor (where "p" stands for positive). The majority carriers in a p-type semiconductor are holes.

Thus, silicon doped with gallium forms a p-type semiconductor.