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Photoelectrochemical Behavior of n-GaAs and n-Al_xGa_(1-x)As in CH_3CN

Casagrande, Louis G. and Juang, Agnes and Lewis, Nathan S. (2000) Photoelectrochemical Behavior of n-GaAs and n-Al_xGa_(1-x)As in CH_3CN. Journal of Physical Chemistry B, 104 (23). pp. 5436-5447. ISSN 1520-6106. http://resolver.caltech.edu/CaltechAUTHORS:20170710-143049120

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Abstract

Current density vs potential, open-circuit voltage vs temperature, and differential capacitance vs potential measurements have been used to show that n-GaAs and n-Al_xGa_(1-x)As electrodes exhibit partial Fermi level pinning in contact with CH_3CN over a wide range of redox potentials. Despite a change of over 1.2 V in redox potential of the solution, the open-circuit voltage only changed by ∼300 mV. The slope of the open-circuit voltage vs redox potential of the solution was typically 0.33−0.44. Differential capacitance vs potential data also yielded a barrier height change of less than 300 mV for over 1.2 V change in the redox potential of the solution. The dependence of the current density vs potential behavior of n-GaAs/CH_3CN−ferricenium−ferrocene^(+/0) on variables such as the illumination intensity, dopant density of the semiconductor, concentration of redox acceptor in the solution, crystal face, electrolyte, and cell temperature was evaluated. The resultant kinetic data indicate that surface-state recombination is the dominant recombination mechanism at these interfaces, which are capable of producing an open-circuit voltage of 0.83 V at a short-circuit current density of 20 mA cm^(-2), as well as energy conversion efficiencies of > 10%. X-ray photoelectron spectroscopy investigation of n-GaAs confirmed surface changes were induced by electrochemical operation of n-GaAs electrodes in CH_3CN−cobaltocenium−cobaltocene^(+/)0 electrolyte. The presence of Fermi level pinning and the existence of changes in n-GaAs and n-Al_xGa_(1-x)As electrode surfaces when these electrodes are in contact with CH3CN−cobaltocenium−cobaltocene^(+/0) electrolyte complicates the extraction of k_(et) values from the steady-state current density vs potential behavior of n-GaAs or n-Al_xGa_(1-x)As/CH_3CN contacts.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/jp9941155DOIArticle
http://pubs.acs.org/doi/abs/10.1021/jp9941155PublisherArticle
ORCID:
AuthorORCID
Lewis, Nathan S.0000-0001-5245-0538
Alternate Title:Photoelectrochemical Behavior of n-GaAs and n-AlxGa1-xAs in CH3CN
Additional Information:© 2000 American Chemical Society. Received: November 18, 1999; In Final Form: February 24, 2000. Publication Date (Web): May 19, 2000. We acknowledge the U.S. Department of Energy, Office of Basic Energy Sciences, for support of this work. We also gratefully acknowledge the Eastman Kodak Company for a gift to Caltech in support of photoelectrochemistry.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)UNSPECIFIED
Eastman Kodak CompanyUNSPECIFIED
Record Number:CaltechAUTHORS:20170710-143049120
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20170710-143049120
Official Citation:Photoelectrochemical Behavior of n-GaAs and n-AlxGa1-xAs in CH3CN Louis G. Casagrande, Agnes Juang, and Nathan S. Lewis The Journal of Physical Chemistry B 2000 104 (23), 5436-5447 DOI: 10.1021/jp9941155
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78906
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:10 Jul 2017 21:50
Last Modified:10 Jul 2017 21:50

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