Q118 / 150 · MHT CET 2026 (16 April Shift 1) · Physics
When a small amount of impurity atoms are added to a semiconductor then generally its resistivity
- Aincreases
- Correct answerBdecreases
- Cdoes not change
- Dmay increase or decrease depending upon the percentage of doping
Solution
When a small amount of impurity atoms is added to a semiconductor, the process is known as doping.
Doping significantly increases the number of charge carriers (either free electrons or holes, depending on the type of impurity) in the semiconductor.
The conductivity of a semiconductor is given by $\sigma = e(n_e \mu_e + n_h \mu_h)$, where $n_e$ and $n_h$ are the number densities of electrons and holes respectively.
Since the number of charge carriers increases, the conductivity of the semiconductor increases.
Resistivity is the reciprocal of conductivity ($\rho = \dfrac{1}{\sigma}$).
Therefore, the resistivity of the semiconductor decreases.
Answer: decreases
Doping significantly increases the number of charge carriers (either free electrons or holes, depending on the type of impurity) in the semiconductor.
The conductivity of a semiconductor is given by $\sigma = e(n_e \mu_e + n_h \mu_h)$, where $n_e$ and $n_h$ are the number densities of electrons and holes respectively.
Since the number of charge carriers increases, the conductivity of the semiconductor increases.
Resistivity is the reciprocal of conductivity ($\rho = \dfrac{1}{\sigma}$).
Therefore, the resistivity of the semiconductor decreases.
Answer: decreases
Hence, the correct answer is option: 'B'.