Concept:When mobile majority carriers diffuse across the junction and recombine, they expose the parent dopant atoms fixed in the crystal lattice.
Formula:$$\text{Donor atom } D^0 \to D^+ + e^-, \quad \text{Acceptor atom } A^0 + e^- \to A^-$$
Solution:- Pentavalent donor atoms in the N-region lose their valence electrons by diffusion, leaving behind fixed positive donor ions (\( D^+ \)).
- Trivalent acceptor atoms in the P-region capture diffusing electrons, leaving behind fixed negative acceptor ions (\( A^- \)).
- This creates a region of positive space charge on the N-side and negative space charge on the P-side of the depletion layer.
Why other options are incorrect:- Option B: Donor ions carry a positive charge after losing an electron, and acceptor ions carry a negative charge after accepting an electron.
- Option C: Mobile electrons and holes recombine near the interface and are largely absent from the depletion region.
- Option D: The crystal remains a single crystalline semiconductor lattice rather than an amorphous structure.
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