Determining Limits of Two-Photon Time-Resolved Photoluminescence for Measuring the Bulk Lifetime in Semiconductors

We investigate the limitations of two-photon time resolved photoluminescence to measure the bulk lifetime of different semiconductor materials used for photovoltaic applicationsThe alternating difference implicit finite-difference time-domain method was employed to simulate the carrier kinetics, following the localized generation of carriers by an ultra-fast laser pulse. Three hypothetical materials were modelled: direct bandgap material for thin-film applications (such as CZTS), direct band-gap for thick--film applications (such as GaAs), and indirect band-gap thick material (such as silicon). It was found that the effective lifetime of the direct band-gap materials remains within an order of magnitude of the bulk lifetime, even for surface recombination velocities up to 10
⁷
cm/s. For the indirect band-gap material, the bulk lifetime is inaccessible, at even moderate surface recombination velocities, due to the combination of high bulk lifetime and high diffusivity. This is the firststudy that highlights the limit of the two-photon time-resolved method for silicon applications.