Concept:The reverse current (reverse saturation current \( I_0 \)) is caused entirely by thermally generated minority carriers swept across the junction by the electric field, which is independent of the external reverse voltage.
Formula:$$I = I_0 \left( e^{\frac{qV}{\eta k T}} - 1 \right) \approx -I_0 \quad (\text{for } V < 0, |V| \gg \frac{kT}{q})$$
Solution:- Once the reverse voltage exceeds a few tenths of a volt, all available minority carriers near the depletion layer are swept across.
- The current saturates at \( I_0 \) and remains constant until the breakdown voltage is reached.
Why other options are incorrect:- Option B: Diodes are non-ohmic devices; current does not increase linearly with reverse voltage.
- Option C: Reverse current does not drop to zero; it remains at \( I_0 \).
- Option D: DC reverse voltage produces a steady DC leakage current without sinusoidal fluctuations.
Quality & Fidelity Assurance:
Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.