Abstract
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 fi nitedifference- 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.
| Original language | English |
|---|---|
| Pages (from-to) | 1109-1116 |
| Number of pages | 8 |
| Journal | Advanced Energy Materials |
| Volume | 2 |
| Issue number | 9 |
| DOIs | |
| Publication status | Published - Sep 2012 |
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ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)
Cite this
Photoelectrochemical behavior of planar and microwire-array Si | GaP electrodes. / Strandwitz, Nicholas C.; Turner-Evans, Daniel B.; Tamboli, Adele C.; Chen, Christopher T.; Atwater, Harry A.; Lewis, Nathan S.
In: Advanced Energy Materials, Vol. 2, No. 9, 09.2012, p. 1109-1116.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Photoelectrochemical behavior of planar and microwire-array Si | GaP electrodes
AU - Strandwitz, Nicholas C.
AU - Turner-Evans, Daniel B.
AU - Tamboli, Adele C.
AU - Chen, Christopher T.
AU - Atwater, Harry A.
AU - Lewis, Nathan S
PY - 2012/9
Y1 - 2012/9
N2 - 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 fi nitedifference- 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.
AB - 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 fi nitedifference- 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.
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U2 - 10.1002/aenm.201100728
DO - 10.1002/aenm.201100728
M3 - Article
VL - 2
SP - 1109
EP - 1116
JO - Advanced Energy Materials
JF - Advanced Energy Materials
SN - 1614-6832
IS - 9
ER -