Practice question

**p-n junction formation** diffusion of holes from p to n and electrons from n to p leaves ionized donors positive on n-side and acceptors negative on p-side, forming space-charge depletion region with electric field directed from n to p (positive to negative), barrier potential V_b ≈0.3 V Ge, 0.7 V Si, opposes further diffusion, drift current due to minority carriers swept by field balances diffusion at equilibrium net current zero. The electric field arises from positive ionized donors on the n-side and negative ionized acceptors on the p-side, directed from the n-side (positive) to the p-side (negative). Substituting values gives N-side to p-side, which matches