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Published May 1, 1994 | metadata_only
Journal Article

Experimental Measurement of Quasi-Fermi Levels at an Illuminated Semiconductor/Liquid Contact


A novel electrode geometry and contacting procedure has allowed measurement of the quasi-Fermi levels, i.e., the apparent electrochemical potentials, of electrons and holes at an illuminated semiconductor / liquid contact. The key feature of our experiments is the use of a lithographically patterned, high purity (100-400 Ω-km n-type float zone material), low dopant density Si sample in contact with CH_3OH-dimethylferrocene^(+/o) solutions. The photogenerated carriers can be collected at the back side of the Si sample through a series of diffused n+ and p^+ points. The lifetime of photogenerated carriers approaches 2 ms in this sample, indicating that electronhole recombination is minimized in the bulk of the semiconductor. Furthermore, surface recombination is minimized by use of low saturation current density, ohmic-selective contacts at the back of the sample. The solid/liquid contact also has a low recombination rate. Therefore, the potentials measured at the diffused points yield values for the quasi-Fermi levels of electrons and holes under illumination of the semiconductor/ liquid contact. Transient photovoltage measurements have also been performed to confirm quantitatively that the quasi-Fermi levels are flat across the Si samples used in this work.

Additional Information

© 1994 American Chemical Society. Received: September 7, 1993; In Final Form: March 12, 1994. We thank the National Science Foundation, Grant CHE-9221311, for support of this work. We also thank Drs. R. A. Sinton, R. M. Swanson, and P. J. Verlinden of SunPower Corp. for providing the lithographically patterned Si samples, and M.X.T. gratefully acknowledges the Link Foundation for a Graduate Fellowship.

Additional details

August 20, 2023
August 20, 2023