Lifetime and diffusivity determination from frequency-domain transient analysis

Minority-carrier lifetime and diffusion coefficient are determined by a new method using the Fourier transforms of transient responses following optical excitation. We demonstrate the method (frequency-domain transient analysis, FDTA) and show that it is more plausible and accurate than other time-domain techniques. The diffusion coefficient in a p-type 0.16-Ω.cm base was measured and found to be 17 ± 1 cm
²
/s. The method can be applied to characterize bulk wafers, epitaxial layers, solar cells, and other bipolar devices. Extension to devices operating in the dark is discussed.