Question
Download Solution PDFThe Fermi level EF in an intrinsic semiconductor, if effective masses of holes and electrons are same, is:
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KVS TGT WET (Work Experience Teacher) Official Paper
Answer (Detailed Solution Below)
Option 2 : \(\rm \frac{E_C+E_V}{2}\)
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Detailed Solution
Download Solution PDFConcept:
Fermi Level:
- The Fermi level in an intrinsic semiconductor is nearly midway between the conductive and valence band.
- Fermi level is the highest energy state occupied by electrons in a material at absolute zero temperature.
- For a p-type semiconductor, there are more holes in the valence band than there are electrons in the conduction band i.e. n < p.
- This implies that the probability of finding an electron near the conduction band edge is smaller than the probability of finding a hole at the valence band edge.
- Therefore, the Fermi level is closer to the valence band in a p-type semiconductor.
Explanation:
- The Fermi level for a p-type lie near the valence band.
- As the temperature increases above zero degrees, the extrinsic carriers in the conduction band and the valence band increases.
- Since the intrinsic concentration also depends on temperature, ni also increases. But for small values of temperature, the extrinsic concentration dominates in comparison to the intrinsic concentration.
- As the temperature continues to increase, the semiconductor starts to lose its extrinsic property and becomes intrinsic, as ni becomes comparable to the extrinsic concentration.
As the temperature increases the p type semiconductor become a simple semiconductor.
Hence, the Fermi level comes back to midway in forbidden energy gap.
Last updated on May 8, 2025
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