Concept:Electric field lines always originate on positive charges and terminate on negative charges. Because the n-side of the depletion region contains positive donor ions and the p-side contains negative acceptor ions, the internal built-in electric field points from n to p.
Formula:$$\vec{E} = -\nabla V \quad \text{(directed from positive space charge to negative space charge)}$$
Solution:- Positive space charge layer = n-side of the junction.
- Negative space charge layer = p-side of the junction.
- Therefore, the internal electric field \(\vec{E}_0\) points from the n-region toward the p-region.
Why other options are incorrect:- Option B: Electric fields point away from positive charges (n-side) and toward negative charges (p-side), not p to n.
- Option C: Terminal wire connections are outside the semiconductor space-charge region.
- Option D: The field is oriented across the planar junction interface, not radially from the surface.
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