Resistivity of semiconductors decreases with a _______ of temperature.

Concept:

Electrical Resistance:

• The measurement of the opposition of the flow of electric current through a cross-section of the material is called the electrical resistance of that material.
• It is denoted by R.
• The relationship between resistance and temperature is given by:

⇒ R = R0 (1 + α Δ T)

Where R0 is resistance at a reference temperature, α is temperature-coefficient of a conductor, and Δ T changes in temperature.

​Explanation:

​Variation of resistance with temperature:

• Semiconductors like Silicon and Germanium contains lesser charges than those of metals but has more charges than insulators. These charge carriers are generated by the thermal breaking of bonds.
• Thus, as the temperature rises, more covalent bonds break, releasing more electrons and the number of electrons and holes will increase which lowers the resistivity rapidly.

• Therefore the resistance of semiconductors decreases with increasing temperature.

Additional Information

• In metals, the current flow due to electrons.​ As the temperature increases, the random motion of the free electron also increases.
  • The increase in random motion of free electrons increases the resistivity of the metals. Therefore the resistance of the metal increases as the temperature increases.

• The resistance of metal decreases as the temperature decreases.