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Photoelectrochemical Behavior of Planar and Microwire-Array Si|GaP Electrodes

Strandwitz, Nicholas C. and Turner-Evans, Daniel B. and Tamboli, Adele C. and Chen, Christopher T. and Atwater, Harry A. and Lewis, Nathan S. (2012) Photoelectrochemical Behavior of Planar and Microwire-Array Si|GaP Electrodes. Advanced Energy Materials, 2 (9). pp. 1109-1116. ISSN 1614-6832. doi:10.1002/aenm.201100728.

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Gallium phosphide exhibits a short diffusion length relative to its optical absorption length, and is thus a candidate for use in wire array geometries that allow light absorption to be decoupled from minority carrier collection. Herein is reported the photoanodic performance of heteroepitaxially grown gallium phosphide on planar and microwire-array Si substrates. The n-GaP|n-Si heterojunction results in a favorable conduction band alignment for electron collection in the silicon. A conformal electrochemical contact to the outer GaP layer is produced using the ferrocenium/ferrocene (Fc^+/Fc) redox couple in acetonitrile. Photovoltages of ∼750 mV under 1 sun illumination are observed and are attributed to the barrier formed at the (Fc^+/Fc)|n-GaP junction. The short-circuit current densities of the composite microwire-arrays are similar to those observed using single-crystal n-GaP photoelectrodes. Spectral response measurements along with a finite-difference-time-domain optical model indicate that the minority carrier diffusion length in the GaP is ∼80 nm. Solid-state current–voltage measurements show that shunting occurs through thin GaP layers that are present near the base of the microwire-arrays. The results provide guidance for further studies of 3D multi-junction photoelectrochemical cells.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Chen, Christopher T.0000-0001-5848-961X
Atwater, Harry A.0000-0001-9435-0201
Lewis, Nathan S.0000-0001-5245-0538
Additional Information:© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Received: November 29, 2011. Published online: June 15, 2012. We acknowledge the National Science Foundation (NSF) Center for Chemical Innovation (CHE-0802907) and DARPA for support. NCS acknowledges the NSF for an American Competitiveness in Chemistry postdoctoral fellowship (CHE-1042006). DBTE acknowledges the NSF for a Graduate Research Fellowship. The authors acknowledge helpful discussions from Dr. Chengxiang Xiang and Prof. Shannon W. Boettcher.
Group:CCI Solar Fuels
Funding AgencyGrant Number
Defense Advanced Research Projects Agency (DARPA)UNSPECIFIED
NSF American Competitiveness in Chemistry Postdoctoral FellowshipCHE-1042006
NSF Graduate Research FellowshipUNSPECIFIED
Subject Keywords:semiconductors; composites; electrodes; electro-optical materials
Issue or Number:9
Record Number:CaltechAUTHORS:20121101-091407028
Persistent URL:
Official Citation:Strandwitz, N. C., Turner-Evans, D. B., Tamboli, A. C., Chen, C. T., Atwater, H. A. and Lewis, N. S. (2012), Photoelectrochemical Behavior of Planar and Microwire-Array Si|GaP Electrodes. Adv. Energy Mater., 2: 1109–1116. doi: 10.1002/aenm.201100728
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35226
Deposited By: Tony Diaz
Deposited On:01 Nov 2012 21:50
Last Modified:09 Nov 2021 23:13

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