Concepts Of Physics MCQ Edition [Volume 2]
- Exam
- Concepts Of Physics MCQ Edition [Volume 2]
- Subject
- Physics
- Chapter
- Semiconductors and Semiconductor Devices
Concepts Of Physics MCQ Edition [Volume 2] · Physics · Semiconductors and Semiconductor Devices
For a semiconductor,
For a semiconductor,
Options
- Aat , there are no free electrons
- Bthe number of free electrons grows with temperature
- Cthere are no free electrons at any given temperature
- Dthe number of free electrons is smaller than in a conductor
Correct answer
D. the number of free electrons is smaller than in a conductor
Step-by-step solution
At , all electrons in a semiconductor are tightly bound in the valence band, leaving the conduction band completely empty. Therefore, there are no free electrons and the semiconductor behaves as a perfect insulator.
As the temperature increases, thermal energy excites electrons from the valence band across the energy gap into the conduction band. Thus, the number of free electrons grows with temperature.
The number density of free electrons in a semiconductor is significantly smaller than that in a conductor, which has an abundance of free electrons due to overlapping bands or partially filled bands.
Therefore, statements (1), (2), and (4) are correct.
As the temperature increases, thermal energy excites electrons from the valence band across the energy gap into the conduction band. Thus, the number of free electrons grows with temperature.
The number density of free electrons in a semiconductor is significantly smaller than that in a conductor, which has an abundance of free electrons due to overlapping bands or partially filled bands.
Therefore, statements (1), (2), and (4) are correct.