Concept:The depletion region is formed when mobile carriers diffuse and recombine, exposing fixed, ionized dopant atoms bound within the crystal lattice.
Formula:$$\text{Depletion Layer Composition: } \text{Fixed Donor Ions } (N_D^+) + \text{Fixed Acceptor Ions } (N_A^-)$$
Solution:- On the N-side of the junction, donor atoms that lost electrons become fixed positive ions (\( N_D^+ \)).
- On the P-side, acceptor atoms that captured electrons become fixed negative ions (\( N_A^- \)).
- The region is depleted of mobile charge carriers (electrons and holes).
Why other options are incorrect:- Option A: The depletion region is defined by the absence of mobile charge carriers.
- Option C: While neutral host atoms are present in the lattice, the defining characteristic is the space charge of ionized dopants.
- Option D: Protons are bound in atomic nuclei and are not free particles.
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