Concept:An ohmic device has a linear \(I\)-\(V\) relationship passing through the origin (constant resistance \(R = V/I\)). A \(\text{p-n}\) junction diode has an exponential \(I\)-\(V\) curve in forward bias and a voltage-independent saturation region in reverse bias, meaning it is non-ohmic in both operating regions.
Formula:$$I = I_s \left( e^{\frac{qV}{\eta k_B T}} - 1 \right) \neq \frac{V}{R}$$
Solution:- Forward bias: The \(I\)-\(V\) curve is exponential (non-linear). Dynamic resistance varies with voltage.
- Reverse bias: The current is flat/nearly constant (non-linear) until breakdown.
- Because Ohm's law (\(V \propto I\)) is not obeyed in either region, the diode is entirely non-ohmic.
Why other options are incorrect:- Option A: Forward bias is non-linear (exponential), hence not ohmic.
- Option B: The diode does not have a constant slope (constant resistance) in either bias region.
- Option D: Non-ohmic behavior is an intrinsic property of the junction at all operating temperatures.
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