With the terminals left open what is the width of the

Question

Calculate the built-in voltage of a junction in which the p and n regions are doped equally with 5×₁₀₁⁶atoms/cm3. Assume ni = 1.5 × ₁₀¹⁰/_cm3. With the terminals left open, what is the width of the depletion region, and how far does it extend into the p and n regions? If the cross-sectional area of the junction is 20 μm2, find the magnitude of the charge stored on either side of the junction.