Bulk Lifetime and Doping in Crystalline Silicon via Two-Photon Absorption Time-Resolved Photoluminescence Decay

Bulk lifetime (
$\tau _{\text{bulk}}$
) and bulk doping (
$N_{\text{dop}}$
) are critical material parameters influencing solar cell performance. The ability to probe spatial variations in
$\tau _{\text{bulk}}$
and
$N_{\text{dop}}$
in ingots, prior to wafer cutting and further processing, would be beneficial to improving the yield and reducing the cost of silicon solar cells. This study demonstrates the capability of the two-photon time-resolved photoluminescence decay method to determine both
$\tau _{\text{bulk}}$
and
$N_{\text{dop}}$
in thick crystalline silicon samples. The use of two photon excitation enables a more uniform carrier generation profile compared to conventional single-photon excitation, making measurements less sensitive to surface effects. The method is verified using an unpassivated
$n$
-type Czochralski silicon disk and found to be in good agreement with the results obtained from the photoluminescence ratio imaging method.