Question

The I-V characteristic of a semiconductor diode in forward bias is a/an:

• A. straight line
• B. parabolic curve
• C. exponentially decreasing curve
• D. exponentially increasing curve
• E. sinusoidal curve

Hint:

Diode forward current follows exponential law \( I \propto e^V \), not linear Ohm’s law.

Answer 1

The Correct Option is D

Step 1: Recall diode current equation.
For a diode: \[ I = I_0 \left(e^{\frac{qV}{kT}} - 1\right) \]

Step 2: Analyze forward bias condition.
In forward bias, voltage \( V \) is positive and large compared to \( kT/q \), so: \[ I \approx I_0 e^{\frac{qV}{kT}} \]

Step 3: Identify nature of relation.
Current increases exponentially with voltage.

Step 4: Graph behavior.
Initially current is small, then increases rapidly (exponential rise).

Step 5: Eliminate incorrect options.
Not linear, not parabolic, not sinusoidal.

Step 6: Confirm correct curve.
Hence, the graph is exponentially increasing.

Step 7: Final conclusion.
\[ \boxed{\text{Exponentially increasing curve}} \] Therefore, correct option: \[ \boxed{(4)} \]