Question

The dominant contribution to current comes from holes in case of

• A. metals
• B. intrinsic semiconductors
• C. p-type extrinsic semiconductors
• D. n-type extrinsic semiconductors

Hint:

p-type: holes majority; n-type: electrons majority.

Answer 1

The Correct Option is C

To determine the dominant contribution to current in different types of materials, we first need to understand the mechanisms of current conduction in metals, intrinsic semiconductors, p-type extrinsic semiconductors, and n-type extrinsic semiconductors. Let's examine each option:

1. Metals: In metals, the current is carried by free electrons because metals have a large number of freely moving conduction electrons. Thus, the dominant charge carriers are electrons.
2. Intrinsic Semiconductors: In intrinsic semiconductors, such as pure silicon or germanium, both electrons and holes contribute nearly equally to the current because the number of electrons is equal to the number of holes at thermal equilibrium.
3. p-type Extrinsic Semiconductors: In a p-type semiconductor, holes are the majority carriers. This is because p-type semiconductors are created by doping the intrinsic semiconductor with an element that has one fewer valence electron than the semiconductor material, such as boron in silicon. This creates "holes" which act as positive charge carriers. Thus, the dominant contribution to current comes from holes.
4. n-type Extrinsic Semiconductors: In n-type semiconductors, electrons are the majority carriers. This is achieved by doping the semiconductor material with an element with an extra valence electron, like phosphorus in silicon, resulting in more free electrons than holes.

Based on the explanation above, the correct answer is p-type extrinsic semiconductors, as the dominant contribution to current in these semiconductors comes from holes.

Thus, the correct option is:

p-type extrinsic semiconductors