Properties of Semiconductors: Practice Problem & Solution
Assertion (A): P-type semiconductor has high density of holes in valence band while N-type semiconductor has high density of electrons in conduction band. Reason (R): In N-type semiconductor, as the density of donor atoms (N_D) is increased, the fermi energy level shifts towards the valence band.
Solution Explained:
To solve this problem, we apply the core principles of Properties of Semiconductors. Understanding the underlying formula is key to arriving at the correct answer below:
P-type semiconductors have a high concentration of holes in the valence band, and N-type semiconductors have a high concentration of electrons in the conduction band. Thus, Assertion (A) is true.
In an N-type semiconductor, increasing the donor atom density (N_D) increases the electron concentration, causing the Fermi energy level to shift closer to the conduction band, not the valence band. Hence, Reason (R) is false.
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