Question
Question: When does the conductivity of Ge semiconductor decrease?...
When does the conductivity of Ge semiconductor decrease?
A
on adding donor impurity
B
On increasing the temperature
C
on decreasing the temperature
D
on adding acceptor impurity
Answer
on decreasing the temperature
Explanation
Solution
The conductivity of a semiconductor depends on the number of free charge carriers (electrons and holes).
- Adding donor or acceptor impurities increases the number of charge carriers (electrons or holes), thus increasing conductivity.
- Increasing temperature provides more thermal energy, generating more electron-hole pairs, thus increasing conductivity.
- Decreasing temperature reduces the thermal energy, leading to fewer electron-hole pairs or ionized impurities, thus decreasing the number of free charge carriers and consequently decreasing conductivity.
Therefore, the conductivity of a Ge semiconductor decreases when the temperature is decreased.