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 forward bias, the current due to majority carrier diffusion is large, typically in the milliampere (mA) range, requiring a milliammeter for measurement. Substituting values gives Milliampere (mA), which matches expected behaviour for this semiconductor device configuration, confirming doping, depletion and rectifier principles.