The factor n in the diode equation I ∝ exp(qV/nkT). It is close to 1 when diffusion current dominates and close to 2 when recombination in the depletion layer dominates, so it indicates junction quality.
Field: PN junctions and diodes
With an ideality factor n this becomes n × 60 mV, so n can be extracted from the slope of a semilog I-V plot.
For an ideal diode (ideality factor n = 1) at room temperat…Subthreshold swing Avalanche breakdown Built-in potential Conductivity modulation Depletion layer Diffusion capacitance Forward bias Junction capacitance (depletion capacitance) Ohmic contact Reverse recovery time