Improvement of Minority Carrier Lifetime and Si Solar Cell Characteristics by Nitric Acid Oxidation Method

Radiation-induced defects are responsible for solar cell degradation. The effects of radiation and annealing on the defects of a GaAs/Ge solar cell are modeled and analyzed in this paper. The electrical performance and spectral response of solar cells irradiated with 150 keV proton are examined. Then, thermal annealing was carried out at 120°C. We found that the proportion of defect recovery after annealing decreases with increasing irradiation fluence. The minority carrier lifetime increases with decreasing defect concentration, which means that the electrical performance of the solar cell is improved. We calculated the defect concentration and minority carrier lifetime with numerical simulation and modeled an improved annealing kinetic equation with experimental results.

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Ebic/Tem Investigation of Defects in Solar Cell Silicon

MRS Proceedings ◽

10.1557/proc-5-167 ◽

1981 ◽

Vol 5 ◽

Cited By ~ 3

Author(s):

Dieter G. Ast ◽

Brian Cunningham ◽

Horst Strunk

Keyword(s):

Solar Cell ◽

Chemical Composition ◽

Carrier Lifetime ◽

Minority Carrier ◽

Minority Carrier Lifetime ◽

Dislocation Network ◽

Junction Depth ◽

First Order ◽

Chemical Impurities ◽

Crystal Volume

ABSTRACTTwo examples are given of the application of EBIC and HVTEM to the study of defects in silicon.An hexagonal dislocation network in a coherent first order twin boundary in WEB silicon shows a three fold symmetry when imaged by EBIC. The observed variation of the minority carrier lifetime at the nodes is consistent with a model which assumes that jogs are particularly strong recombination sites at a dislocation.EBIC and STEM observations on unprocessed and processed EFG ribbon show that the phosphorus diffused junction depth is not uniform, and that a variety of chemical impurities precipitate out during processing. Two kinds of precipitates are found i) 10 nm or less in size, located at the dislocation nodes in sub-boundary like dislocation arrangements formed during processing and ii) large precipitates, the chemical composition of which has been partially identified. These large precipitates emit dense dislocations tangles into the adjacent crystal volume.

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Relationship Between Minority Carrier Parameters and Solar Cell Characteristics of Electromagnetic Cast Polycrystalline Silicon

MRS Proceedings ◽

10.1557/proc-324-379 ◽

1993 ◽

Vol 324 ◽

Author(s):

Eiichi Suzuki ◽

Kyojiro Kaneko ◽

Toru Nunoi

Keyword(s):

Solar Cells ◽

Solar Cell ◽

Polycrystalline Silicon ◽

High Efficiency ◽

Carrier Lifetime ◽

Minority Carrier ◽

Small Variation ◽

Minority Carrier Lifetime ◽

The Relationship ◽

And Diffusion

AbstractThe relationship between minority carrier properties and solar cell characteristics of electromagnetic (EM) cast polycrystalline Si has experimentally been investigated. The minority carrier lifetime τ and diffusion coefficient D were evaluated by a novel dual mercury probe method. The solar cell characteristics, e.g., a conversion efficiency η were measured by fabricating experimental solar cells using the corresponding wafers. The wafer showing high-η (13.1%) has relatively high τ (av. 8.2 μs) with small variation of I) (av. 29.6 cm2/s). On the contrary, the low-η (11%) wafer shows low τ (av. 1.1 μs), including some inferior portions with very low τ of less than 0.5 μs. It is also shown that D drastically deteriorates with decreasing τ if τ is less than around 2 μs. To realize high efficiency polycrystalline solar cells, the wafers with high value of τ and without considerably low-τ portions are needed.

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