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CuInSe 2 (CIS) thin films ~ 500-650 Å in thickness have been deposited on c-Si substrates by two-stage thermal co-evaporation starting either from In 2 Se 3 [according to In 2 Se 3 + (2Cu+Se) → 2(CuInSe 2 )] or from Cu 2-x Se [according to Cu 2 Se + (2In+3Se) → 2(CuInSe 2 )]. The design of such processes is facilitated by accurate calibrations of Cu and In 2 Se 3 growth rates on substrate/film surfaces obtained by real time spectroscopic ellipsometry (RTSE). The two-stage deposited CIS films were also studied by RTSE to deduce (i) the evolution of film structure upon conversion of the starting In 2 Se 3 or Cu 2-x Se films to CIS via Cu+Se or In+Se co-evaporation, respectively, and (ii) the complex dielectric functions of the starting films as well as the resulting CIS. The goal is to fabricate CIS that develops large grains as early as possible during growth for high quality materials in tandem solar cell applications. Results indicate that by depositing Cu 2-x Se in the first stage and exposing the film to In+Se flux in the second stage [as in the third stage of a three-stage CIS process] well-defined bandgap critical points with no detectable subgap absorption are noted in films as thin as 650 Å.
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Ag Alloying and KF Treatment Effects on Low Bandgap CIGS Solar Cells
Silver alloying and KF post-deposition treatments are 2 approaches to increase the efficiency of CIGS solar cells. Although it has been shown in the literature that KF improves ACIGS device performance for reduced KF amounts, in present studies of lower bandgap ACIGS, KF is detrimental on Voc. J-V curves also exhibit light-to-dark crossover in ACIS+KF films. This has motivated a study on the growth of CdS on low bandgap (A)CIS films with and without KF. SEM and GDOES suggest a different CdS growth on Ag alloyed CIS.
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- Award ID(s):
- 1507351
- PAR ID:
- 10084306
- Date Published:
- Journal Name:
- Published in: 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC)
- Page Range / eLocation ID:
- 1652 to 1654
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/PVSC.2018.8547372
