Practice question

**Depletion region** also called space-charge region, thickness typically 0.5 μm, contains no mobile carriers, only fixed ions, negative on p-side, positive on n-side, diffusion current due to concentration gradient, drift current due to field, equilibrium when J_drift + J_diff =0, voltage drop mainly across depletion region. In reverse bias, the diode allows only a small reverse saturation current ( μ A ), resulting in a very high resistance compared to the low resistance in forward bias. Substituting values gives High, which matches expected behaviour for this semiconductor device configuration, confirming doping, depletion and rectifier principles.