Question

Discuss the characteristics of (i) forward biasing and (ii) reverse biasing in \( p\)-\(n \) junction. Explain the cause of origin and direction of current in both conditions.

Hint:

In forward bias, current flows easily; in reverse bias, only leakage current flows.

Answer 1

(i) Forward Biasing: Step 1: In forward bias, the \( p \)-side is connected to the positive terminal and the \( n \)-side to the negative terminal. Step 2: The depletion region narrows, allowing current to flow. \[ I_{\text{forward}} \approx I_s (e^{\frac{V}{kT}} - 1) \] Step 3: Current flows from \( p \) to \( n \). \[ \boxed{\text{Current increases exponentially with voltage.}} \] (ii) Reverse Biasing: Step 1: In reverse bias, the \( p \)-side is connected to the negative terminal and the \( n \)-side to the positive terminal. Step 2: The depletion region widens, preventing current flow. Step 3: A small leakage current due to minority carriers flows. \[ \boxed{\text{Current remains nearly constant.}} \]