Charge carrier kinetics, especially their lifetime, ultimately determine the performance of silicon photovoltaic cells. With a thin layer of silicon, where carriers are generated by sunlight, it is important to control and understand their (unwanted) recombination not only at bulk but also at the surface. However, decoupling these is challenging using laboratory characterisation techniques.
A new method of photoexcited muon spin relaxation (photo-μSR) has been developed and, in this study, used to separate the bulk and surface recombination. Because the muons can be implanted at different depths within a Si wafer, the carrier lifetime spectrum can be measured at specific points. This enabled the researchers to use a simple model to separate the bulk and surface contributions. This technique could be extended to a range of other semiconductor systems, including power electronic devices.
Related publication: Decoupling bulk and surface recombination properties in silicon by depth-dependent carrier lifetime measurements, Appl. Phys. Lett., 118, 252105 (2021) DOI: 10.1063/5.0054291