Proof-Of-Concept Framework To Separate Recombination Processes In Thin Silicon Wafers Using Transient Free-Carrier Absorption Spectroscopy

We present a proof-of-concept framework to independently determine the bulk Shockley-Read-Hall (SRH) lifetime and surface recombination velocity in silicon wafers self-consistently. We measure the transient decay of free-carrier absorption (FCA) using two different excitation wavelengths (1050 and 750 nm) for p-type crystalline Si (c-Si) wafers over a wide injection range and fit the FCA transients for the two excitation wavelengths in a coupled manner. In this way, we can estimate the surface recombination lifetime accurately. However, we find that the capability to uniquely measure extrinsic bulk-SRH recombination is challenging in the presence of other recombination processes and can be broadly categorized into five different regimes depending on the relative strengths of each recombination pathway. (C) 2015 AIP Publishing LLC.