Decoupling surface- and bulk-limited lifetimes in 100-μm thin silicon using transient absorption pump-probe spectroscopy

The transient decay of excess photo-generated carriers in a 100-μm thin unpassivated crystalline Si (c-Si) wafer is measured using transient absorption pump-probe spectroscopy with two excitation wavelengths (750 nm and 1050 nm), based on the principle of free-carrier absorption. To decouple the bulk-and surface-limited lifetimes, we use state-of-the-art simulation software Sentaurus TCAD [1] to model the experimentally obtained decay characteristics of minority carrier densities. We show that by combining transient absorption pump-probe spectroscopy technique with TCAD simulations, reasonable bounds for both bulk and surface recombination parameters can be determined. The value obtained for the surface recombination velocity is consistent with literature and a lower limit for bulk lifetime can be obtained.