Concept:Reverse saturation current (leakage current) is caused by the drift of minority charge carriers generated thermally within or near the depletion region.
Formula:$$I_{\text{reverse}} \approx I_0 = e A \left( \frac{D_n n_p}{L_n} + \frac{D_p p_n}{L_p} \right)$$
Solution:- Thermal energy continuously creates electron-hole pairs throughout the semiconductor.
- Minority electrons in the P-region and minority holes in the N-region that wander into the depletion layer are swept across by the electric field.
- This creates a small, temperature-dependent reverse leakage current (typically on the order of \( \mu\text{A} \) for Ge and \( \text{nA} \) for Si).
Why other options are incorrect:- Options A & B: Majority carriers face a large potential barrier in reverse bias and cannot cross the junction.
- Option C: Immobile ionic cores remain bound within the semiconductor lattice and do not conduct current.
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