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General Lifetime Measurements

Transient and quasi-steady-state photoconductance decay measurements of lifetime are the limiting cases of the general equation given as [1].

In the case of transient measurements, the pulse of light is only to excite the carriers and is off during the actual measurement so that G(t) = 0. For the QSS measurements, it is assumed that the light is varying very slowly so that d(Δn)/dt = 0.

The generalized form of the equation is useful when the flash and wafer have similar time constants.

Illumination at Reference Cell and Carrier Density

Minority-Carrier Lifetime (no Auger correction) vs. Carrier Density