Time-resolved Photoluminescence for the Measurement of the Effective Carrier Lifetime in Si Photonic Structures

Two-dimensional photonic structures for advanced light trapping in thin film crystalline silicon solar cells are mainly studied from the optical point of view. However, the nanopatterning process can induce etching damage that can reduce the minority carrier lifetime and the cell performance. Time-resolved photoluminescence is used to evaluate the effect of photonic structures on the effective lifetime of nanopatterned silicon epi-layers. Two excitation wavelengths are used to evaluate separately the quality of the bulk and the patterned surface of the epi-layers. The measurements are discussed in connection with the carrier generation maps calculated with Finite-Difference Time Domain simulations.