Analysis and capacitive measurement of the built-in-field parameter in highly doped emitters

An elementary theory of a strongly asymmetric n⁺-n-p junction, assuming an exponential tail of the donor concentration profile in the depletion layer, is presented and supported by numerical computations. The drastic effect of the built-in field upon the minority carrier flow is discussed. A detailed expression of the static capacitance is then derived and shown to lead to an improved measurement of the law, capable of yielding the internal field parameter around the edge of the depletion layer in the emitter. Typical experimental results are reported and discussed.