Details
| Original language | English |
|---|---|
| Article number | 015001 |
| Journal | Semiconductor Science and Technology |
| Volume | 23 |
| Issue number | 1 |
| Publication status | Published - 1 Jan 2008 |
| Externally published | Yes |
Abstract
The traditional approach to harnessing the impurity-photovoltaic effect to improve solar cell performance is plagued by additional recombination caused by the impurity centres. This extra recombination channel is usually deemed to outweigh the benefits of additional generation of electron-hole pairs via sub-band-gap absorption through the impurity levels. Here we consider an alternative approach that restricts the impurity levels to a film with a wider band gap at the rear of a solar cell, isolating the impurities from the minority carriers generated in the base, but, in principle, still allowing impurity-generated carriers to contribute to the cell current. Initial proof-of-concept experiments show that implantation of silicon ions into amorphous silicon films on the rear of crystalline silicon wafers results in the desired increase in sub-band-gap absorptance of infrared photons, without degrading the surface passivation properties of the amorphous layer. However, these defect states are not thermally stable, and in any case do not result in additional carriers being injected into the silicon wafer itself, either because the infrared-generated carriers relax back to the valence band before the second photon can be absorbed, or because the free carriers recombine before reaching the wafer interface. Subsequent attempts involving implantation of iron and erbium impurities to generate stable absorption centres in the amorphous silicon films also failed to inject additional carriers into the crystalline wafer. Possible modifications that may alleviate these problems are discussed.
ASJC Scopus subject areas
- Materials Science(all)
- Electronic, Optical and Magnetic Materials
- Physics and Astronomy(all)
- Condensed Matter Physics
- Engineering(all)
- Electrical and Electronic Engineering
- Materials Science(all)
- Materials Chemistry
Sustainable Development Goals
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In: Semiconductor Science and Technology, Vol. 23, No. 1, 015001, 01.01.2008.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Electronically-coupled up-conversion
T2 - An alternative approach to impurity photovoltaics in crystalline silicon
AU - MacDonald, D.
AU - McLean, K.
AU - Deenapanray, P. N.K.
AU - De Wolf, S.
AU - Schmidt, J.
PY - 2008/1/1
Y1 - 2008/1/1
N2 - The traditional approach to harnessing the impurity-photovoltaic effect to improve solar cell performance is plagued by additional recombination caused by the impurity centres. This extra recombination channel is usually deemed to outweigh the benefits of additional generation of electron-hole pairs via sub-band-gap absorption through the impurity levels. Here we consider an alternative approach that restricts the impurity levels to a film with a wider band gap at the rear of a solar cell, isolating the impurities from the minority carriers generated in the base, but, in principle, still allowing impurity-generated carriers to contribute to the cell current. Initial proof-of-concept experiments show that implantation of silicon ions into amorphous silicon films on the rear of crystalline silicon wafers results in the desired increase in sub-band-gap absorptance of infrared photons, without degrading the surface passivation properties of the amorphous layer. However, these defect states are not thermally stable, and in any case do not result in additional carriers being injected into the silicon wafer itself, either because the infrared-generated carriers relax back to the valence band before the second photon can be absorbed, or because the free carriers recombine before reaching the wafer interface. Subsequent attempts involving implantation of iron and erbium impurities to generate stable absorption centres in the amorphous silicon films also failed to inject additional carriers into the crystalline wafer. Possible modifications that may alleviate these problems are discussed.
AB - The traditional approach to harnessing the impurity-photovoltaic effect to improve solar cell performance is plagued by additional recombination caused by the impurity centres. This extra recombination channel is usually deemed to outweigh the benefits of additional generation of electron-hole pairs via sub-band-gap absorption through the impurity levels. Here we consider an alternative approach that restricts the impurity levels to a film with a wider band gap at the rear of a solar cell, isolating the impurities from the minority carriers generated in the base, but, in principle, still allowing impurity-generated carriers to contribute to the cell current. Initial proof-of-concept experiments show that implantation of silicon ions into amorphous silicon films on the rear of crystalline silicon wafers results in the desired increase in sub-band-gap absorptance of infrared photons, without degrading the surface passivation properties of the amorphous layer. However, these defect states are not thermally stable, and in any case do not result in additional carriers being injected into the silicon wafer itself, either because the infrared-generated carriers relax back to the valence band before the second photon can be absorbed, or because the free carriers recombine before reaching the wafer interface. Subsequent attempts involving implantation of iron and erbium impurities to generate stable absorption centres in the amorphous silicon films also failed to inject additional carriers into the crystalline wafer. Possible modifications that may alleviate these problems are discussed.
UR - http://www.scopus.com/inward/record.url?scp=37249093533&partnerID=8YFLogxK
U2 - 10.1088/0268-1242/23/1/015001
DO - 10.1088/0268-1242/23/1/015001
M3 - Article
AN - SCOPUS:37249093533
VL - 23
JO - Semiconductor Science and Technology
JF - Semiconductor Science and Technology
SN - 0268-1242
IS - 1
M1 - 015001
ER -