Abstract
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-CH3OH 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-CH3OH 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.
| Original language | English |
|---|---|
| Pages (from-to) | 2329-2338 |
| Number of pages | 10 |
| Journal | Energy and Environmental Science |
| Volume | 7 |
| Issue number | 7 |
| DOIs | |
| Publication status | Published - 2014 |
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ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Environmental Chemistry
- Pollution
- Nuclear Energy and Engineering
Cite this
Operation of lightly doped Si microwires under high-level injection conditions. / Santori, Elizabeth A.; Strandwitz, Nicholas C.; Grimm, Ronald L.; Brunschwig, Bruce S.; Atwater, Harry A.; Lewis, Nathan S.
In: Energy and Environmental Science, Vol. 7, No. 7, 2014, p. 2329-2338.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Operation of lightly doped Si microwires under high-level injection conditions
AU - Santori, Elizabeth A.
AU - Strandwitz, Nicholas C.
AU - Grimm, Ronald L.
AU - Brunschwig, Bruce S.
AU - Atwater, Harry A.
AU - Lewis, Nathan S
PY - 2014
Y1 - 2014
N2 - 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-CH3OH 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-CH3OH 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.
AB - 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-CH3OH 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-CH3OH 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.
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U2 - 10.1039/c4ee00202d
DO - 10.1039/c4ee00202d
M3 - Article
VL - 7
SP - 2329
EP - 2338
JO - Energy and Environmental Science
JF - Energy and Environmental Science
SN - 1754-5692
IS - 7
ER -