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. During junction formation, electrons diffuse from n-side to p-side, leaving behind immobile positive ionized donors on the n-side, forming the positive space-charge region. Substituting values gives N-side, which matches expected behaviour for this semiconductor device