Question:

The probability of electrons to be found in the conduction band of an intrinsic semiconductor at a finite temperature :

Updated On: Aug 15, 2022
  • decreases exponentially with increasing band gap
  • increases exponentially with increasing band gap
  • decreases with increasing temperature
  • is independent of the temperature and the band gap
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The Correct Option is A

Solution and Explanation

The fermi function $f(E)$ gives the probability that a given available electron energy state will be occupied at a given temperature. The fermi function comes from Fermi-Dirac statistics and has the form $f(E)=\frac{1}{E^{\left(E-E_{F}\right) / k T}+1}$ The basic nature of this function dictates that at ordinary temperatures, most of the levels up to the fermi level are filled. At higher temperature, a larger fraction of the electrons can bridge this gap and participate in electrical conduction. Hence, at finite temperature, the probability decreases exponentially with increasing band gap.
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Concepts Used:

Semiconductors

Semiconductors are a crystalline solid materials, whose electrical conductivity lies between a conductor and an insulator. Semiconductors are mainly used in the manufacturing of electronic devices like capacitors, transistors, diodes, Integrated circuits, etc.

Properties of Semiconductor:

  1. Semiconductor acts like an insulator at Zero Kelvin. On increasing the temperature, it works as a conductor.
  2. Due to their exceptional electrical properties, semiconductors can be modified by doping to make semiconductor devices suitable for energy conversion, switches, and amplifiers.
  3. Lesser power losses.

Uses of Semiconductor:

  1. Semiconductors are widely used in manufacturing electronics devices like transistors, diodes, sensors, integrated circuits.
  2. Semiconductors are widely used in all electronic devices, like mobile phones, digital cameras, communication devices, trains, ATMs, etc.