Question

Choose the correct statement from the following.

• A. Silicon is a direct band gap semiconductor.
• B. Conductivity of metals decreases with increase in temperature.
• C. Conductivity of semiconductors decreases with increase in temperature.
• D. Gallium Arsenide is an indirect band gap semiconductor.

Hint:

In metals, conductivity decreases with temperature, while in semiconductors, it increases due to thermal excitation of charge carriers.

Answer 1

The Correct Option is B

Step 1: In metals, as the temperature increases, the atomic vibrations increase, which leads to more collisions between free electrons and atoms. This causes the electrical resistance (and thus conductivity) to decrease with increasing temperature.

Step 2: In semiconductors, the conductivity increases with temperature as more charge carriers are thermally excited.

Step 3: Silicon is an indirect band gap semiconductor, and Gallium Arsenide (GaAs) is a direct band gap semiconductor. Thus, options (A), (C), and (D) are incorrect.
Thus, the correct answer is (B).