Dynamics of Photoexcited Carrier Relaxation and Recombination in CdTe/CdS Thin Films

D. H. Levi; B. D. Fluegel; R. K. Ahrenkiel; A. D. Compaan; L. M. Woods

doi:10.1109/pvsc.1996.564277

Dynamics of Photoexcited Carrier Relaxation and Recombination in CdTe/CdS Thin Films

D. H. Levi, B. D. Fluegel, R. K. Ahrenkiel, A. D. Compaan, L. M. Woods

Materials Science

Research output: Contribution to conference › Paper › peer-review

6 Scopus Citations

Abstract

Efficiency-limiting defects in photovoltaic devices are readily probed by time-resolved spectroscopy. This paper presents the first direct optical measurements of the relaxation and recombination pathways of photoexcited carriers in the CdS window layer of CdTe/CdS polycrystalline thin films. We utilize the complimentary techniques of femtosecond time-resolved differential absorption (TRDA) and picosecond time-resolved photoluminescence (TRPL) to determine the relaxation and recombination mechanisms in these films. Comparison between samples with systematic variations in their CdS layers leads to several conclusions. Photoexcited holes are very rapidly captured by deep traps where they remain until recombining with electrons in shallow traps. The hole trapping states are most likely produced by tellurium substituting for sulfur in the CdS lattice. We postulate that reduction of tellurium diffusion into CdS during growth may increase the spectral response of CdTe/CdS solar cells for photon energies above 2.5 eV by reducing or eliminating these defect sites.

Original language	American English
Pages	913-916
Number of pages	4
DOIs	https://doi.org/10.1109/pvsc.1996.564277 https://doi.org/10.1109/PVSC.1996.564277
State	Published - 1996
Event	Proceedings of the 1996 25th IEEE Photovoltaic Specialists Conference - Washington, DC, USA Duration: 13 May 1996 → 17 May 1996

Conference

Conference	Proceedings of the 1996 25th IEEE Photovoltaic Specialists Conference
City	Washington, DC, USA
Period	13/05/96 → 17/05/96

NREL Publication Number

NREL/CP-22422

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Levi, D. H., Fluegel, B. D., Ahrenkiel, R. K., Compaan, A. D., & Woods, L. M. (1996). Dynamics of Photoexcited Carrier Relaxation and Recombination in CdTe/CdS Thin Films. 913-916. Paper presented at Proceedings of the 1996 25th IEEE Photovoltaic Specialists Conference, Washington, DC, USA. https://doi.org/10.1109/pvsc.1996.564277, https://doi.org/10.1109/PVSC.1996.564277

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title = "Dynamics of Photoexcited Carrier Relaxation and Recombination in CdTe/CdS Thin Films",

abstract = "Efficiency-limiting defects in photovoltaic devices are readily probed by time-resolved spectroscopy. This paper presents the first direct optical measurements of the relaxation and recombination pathways of photoexcited carriers in the CdS window layer of CdTe/CdS polycrystalline thin films. We utilize the complimentary techniques of femtosecond time-resolved differential absorption (TRDA) and picosecond time-resolved photoluminescence (TRPL) to determine the relaxation and recombination mechanisms in these films. Comparison between samples with systematic variations in their CdS layers leads to several conclusions. Photoexcited holes are very rapidly captured by deep traps where they remain until recombining with electrons in shallow traps. The hole trapping states are most likely produced by tellurium substituting for sulfur in the CdS lattice. We postulate that reduction of tellurium diffusion into CdS during growth may increase the spectral response of CdTe/CdS solar cells for photon energies above 2.5 eV by reducing or eliminating these defect sites.",

author = "Levi, {D. H.} and Fluegel, {B. D.} and Ahrenkiel, {R. K.} and Compaan, {A. D.} and Woods, {L. M.}",

year = "1996",

doi = "10.1109/pvsc.1996.564277",

language = "American English",

pages = "913--916",

note = "Proceedings of the 1996 25th IEEE Photovoltaic Specialists Conference ; Conference date: 13-05-1996 Through 17-05-1996",

}

Levi, DH, Fluegel, BD, Ahrenkiel, RK, Compaan, AD & Woods, LM 1996, 'Dynamics of Photoexcited Carrier Relaxation and Recombination in CdTe/CdS Thin Films', Paper presented at Proceedings of the 1996 25th IEEE Photovoltaic Specialists Conference, Washington, DC, USA, 13/05/96 - 17/05/96 pp. 913-916. https://doi.org/10.1109/pvsc.1996.564277, https://doi.org/10.1109/PVSC.1996.564277

TY - CONF

T1 - Dynamics of Photoexcited Carrier Relaxation and Recombination in CdTe/CdS Thin Films

AU - Levi, D. H.

AU - Fluegel, B. D.

AU - Ahrenkiel, R. K.

AU - Compaan, A. D.

AU - Woods, L. M.

PY - 1996

Y1 - 1996

N2 - Efficiency-limiting defects in photovoltaic devices are readily probed by time-resolved spectroscopy. This paper presents the first direct optical measurements of the relaxation and recombination pathways of photoexcited carriers in the CdS window layer of CdTe/CdS polycrystalline thin films. We utilize the complimentary techniques of femtosecond time-resolved differential absorption (TRDA) and picosecond time-resolved photoluminescence (TRPL) to determine the relaxation and recombination mechanisms in these films. Comparison between samples with systematic variations in their CdS layers leads to several conclusions. Photoexcited holes are very rapidly captured by deep traps where they remain until recombining with electrons in shallow traps. The hole trapping states are most likely produced by tellurium substituting for sulfur in the CdS lattice. We postulate that reduction of tellurium diffusion into CdS during growth may increase the spectral response of CdTe/CdS solar cells for photon energies above 2.5 eV by reducing or eliminating these defect sites.

AB - Efficiency-limiting defects in photovoltaic devices are readily probed by time-resolved spectroscopy. This paper presents the first direct optical measurements of the relaxation and recombination pathways of photoexcited carriers in the CdS window layer of CdTe/CdS polycrystalline thin films. We utilize the complimentary techniques of femtosecond time-resolved differential absorption (TRDA) and picosecond time-resolved photoluminescence (TRPL) to determine the relaxation and recombination mechanisms in these films. Comparison between samples with systematic variations in their CdS layers leads to several conclusions. Photoexcited holes are very rapidly captured by deep traps where they remain until recombining with electrons in shallow traps. The hole trapping states are most likely produced by tellurium substituting for sulfur in the CdS lattice. We postulate that reduction of tellurium diffusion into CdS during growth may increase the spectral response of CdTe/CdS solar cells for photon energies above 2.5 eV by reducing or eliminating these defect sites.

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DO - 10.1109/pvsc.1996.564277

M3 - Paper

AN - SCOPUS:0030414072

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EP - 916

T2 - Proceedings of the 1996 25th IEEE Photovoltaic Specialists Conference

Y2 - 13 May 1996 through 17 May 1996

ER -

Dynamics of Photoexcited Carrier Relaxation and Recombination in CdTe/CdS Thin Films

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