Question

Given that the electronic conductivity of a material increases with temperature, this material is most likely:

• A. A metal
• B. An intrinsic semiconductor
• C. A superconductor
• D. A polymer

Hint:

Semiconductors love the heat — more temperature means more charge carriers and higher conductivity!

Answer 1

The Correct Option is B

In an intrinsic semiconductor, conductivity is primarily determined by the thermal excitation of electrons from the valence band to the conduction band. As temperature increases, more electrons gain enough energy to cross the band gap, thereby increasing the number of charge carriers (electrons and holes). This leads to a significant increase in electrical conductivity with temperature.
In contrast, metals exhibit a decrease in conductivity with temperature because increased thermal vibrations scatter conduction electrons more, increasing resistance.
Comparison with other materials:

• (A) Metal: Conductivity decreases with temperature due to increased electron scattering.
• (C) Superconductor: Shows zero resistance below a critical temperature but loses superconductivity if temperature rises above it.
• (D) Polymer: Most polymers are insulators or poor conductors unless specially modified (e.g., doped).

Therefore, if a material's conductivity increases with temperature, it most likely behaves like an intrinsic semiconductor.