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Operation of lightly doped Si microwires under high-level injection conditions

Santori, Elizabeth A. and Strandwitz, Nicholas C. and Grimm, Ronald L. and Brunschwig, Bruce S. and Atwater, Harry A. and Lewis, Nathan S. (2014) Operation of lightly doped Si microwires under high-level injection conditions. Energy and Environmental Science, 7 (7). pp. 2329-2338. ISSN 1754-5692. doi:10.1039/C4EE00202D.

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The operation of lightly doped Si microwire arrays under high-level injection conditions was investigated by measurement of the current-potential behavior and carrier-collection efficiency of the wires in contact with non-aqueous electrolytes, and through complementary device physics simulations. The current-potential behavior of the lightly doped Si wire array photoelectrodes was dictated by both the radial contact and the carrier-selective back contact. For example, the Si microwire arrays exhibited n-type behavior when grown on a n^(+)-doped substrate and placed in contact with the 1,1′-dimethylferrocene+/0–CH_(3)OH redox system. The microwire arrays exhibited p-type behavior when grown on a p^(+)-doped substrate and measured in contact with a redox system with a sufficiently negative Nernstian potential. The wire array photoelectrodes exhibited internal quantum yields of ~0.8, deviating from unity for these radial devices. Device physics simulations of lightly doped n-Si wires in radial contact with the 1,1′-dimethylferrocene^(+/0)–CH_(3)OH redox system showed that the carrier-collection efficiency should be a strong function of the wire diameter and the carrier lifetime within the wire. Small diameter (d < 200 nm) wires exhibited low quantum yields for carrier collection, due to the strong inversion of the wires throughout the wire volume. In contrast, larger diameter wires (d > 400 nm) exhibited higher carrier collection efficiencies that were strongly dependent on the carrier lifetime in the wire, and wires with carrier lifetimes exceeding 5 μs were predicted to have near-unity quantum yields. The simulations and experimental measurements collectively indicated that the Si microwires possessed carrier lifetimes greater than 1 μs, and showed that radial structures with micron dimensions and high material quality can result in excellent device performance with lightly doped, structured semiconductors.

Item Type:Article
Related URLs:
URLURL TypeDescription material
Grimm, Ronald L.0000-0003-0407-937X
Brunschwig, Bruce S.0000-0002-6135-6727
Atwater, Harry A.0000-0001-9435-0201
Lewis, Nathan S.0000-0001-5245-0538
Additional Information:© 2014 Royal Society of Chemistry. Received 18th January 2014; Accepted 18th March 2014. We acknowledge the Department of Energy Office of Basic Energy Sciences grant DOE DE-FG02-03ER15483, and BP for financial support. NCS acknowledges the NSF for an American Competitiveness in Chemistry postdoctoral fellowship (CHE-1042006). Critical support and infrastructure for this work were provided by the Kavli Nanoscience Institute and the Molecular Materials Research Center at Caltech. The angle-resolved optical characterization work was supported by the US Department of Energy ‘Light-Material Interactions in Energy Conversion’ Energy Frontier Research Center Award (grant DESC0001293).
Group:Kavli Nanoscience Institute
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG02-03ER15483
NSF Postdoctoral FellowshipCHE-1042006
Kavli Nanoscience InstituteUNSPECIFIED
Caltech Beckman InstituteUNSPECIFIED
Department of Energy (DOE)DE-SC0001293
Issue or Number:7
Record Number:CaltechAUTHORS:20140724-082011157
Persistent URL:
Official Citation:Santori, E. A., Strandwitz, N. C., Grimm, R. L., Brunschwig, B. S., Atwater, H. A., & Lewis, N. S. (2014). Operation of lightly doped Si microwires under high-level injection conditions. [10.1039/C4EE00202D]. Energy & Environmental Science, 7(7), 2329-2338. doi: 10.1039/c4ee00202d
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:47454
Deposited On:24 Jul 2014 19:41
Last Modified:10 Nov 2021 17:39

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