Interpretation of Transient Photocurrents in Coplanar and Sandwich PIN Microcrystalline Silicon Structures

Reynolds, S.; Smirnov, V. A.; Main, C.; Finger, F.; Carius, R.

doi:10.1557/proc-808-a5.7

Cited by 6 publications

(5 citation statements)

References 14 publications

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“…Unlike the situation for a-Si:H, the conduction bandtail width has not been extensively studied in nc-Si:H. The assumption that its breadth remains negligible near room-temperature does appear consistent with transient photocurrent measurements by Reynolds, et al [25].…”

Section: Hole Mobility Limit For Nanocrystalline Silicon Solar Cellssupporting

confidence: 61%

Carrier drift-mobilities and solar cell models for amorphous and nanocrystalline silicon

Schiff

2009

MRS Proc.

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Hole drift mobilities in hydrogenated amorphous silicon (a-Si:H) and nanocrystalline silicon (nc-Si:H) are in the range of 10 -3 to 1 cm 2 /Vs at room-temperature. These low drift mobilities establish corresponding hole mobility limits to the power generation and useful thicknesses of the solar cells. The properties of as-deposited a-Si:H nip solar cells are quite close to their hole mobility limit, but the corresponding limit has not been examined for nc-Si:H solar cells. We explore the predictions for nc-Si:H solar cells based on parameters and values estimated from hole drift-mobility and related measurements. The indicate that the hole mobility limit for nc-Si:H cells corresponds to an optimum intrinsic-layer thickness of 2-3 µm, whereas the best nc-Si:H solar cells (10% conversion efficiency) have thicknesses around 2 µm.

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Section: Hole Mobility Limit For Nanocrystalline Silicon Solar Cellssupporting

confidence: 61%

Carrier drift-mobilities and solar cell models for amorphous and nanocrystalline silicon

Schiff

2009

MRS Proc.

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“…19,20 The characteristic energy of the conduction-band tail is 33 meV. 21 In our simulations we assume for both band tails a characteristic energy of 31 eV. Furthermore, in Refs.…”

Section: 17mentioning

confidence: 99%

Determination of the mobility gap of intrinsic μc-Si:H in p-i-n solar cells

Pieters

Stiebig

Zeman

et al. 2009

Journal of Applied Physics

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Microcrystalline silicon (μc-Si:H) is a promising material for application in multijunction thin-film solar cells. A detailed analysis of the optoelectronic properties is impeded by its complex microstructural properties. In this work we will focus on determining the mobility gap of μc-Si:H material. Commonly a value of 1.1eV is found, similar to the bandgap of crystalline silicon. However, in other studies mobility gap values have been reported to be in the range of 1.48–1.59eV, depending on crystalline volume fraction. Indeed, for the accurate modeling of μc-Si:H solar cells, it is paramount that key parameters such as the mobility gap are accurately determined. A method is presented to determine the mobility gap of the intrinsic layer in a p-i-n device from the voltage-dependent dark current activation energy. We thus determined a value of 1.19eV for the mobility gap of the intrinsic layer of an μc-Si:H p-i-n device. We analyze the obtained results in detail through numerical simulations of the μc-Si:H p-i-n device. The applicability of the method for other than the investigated devices is discussed with the aid of numerical simulations.

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“…The bandtail multiple-trapping model appears to account well for the temporal and thermal variations of the hole displacement. Bandtail states have previously been proposed to account for electron paramagnetic resonance spectra, 14,15 for photocarrier recombination experiments, 16 and transient photoconductivity measurements 17 in c-Si. One paperreporting temperature-dependent ambipolar diffusion lengths 16 -estimates an exponential valence bandtail width of 26 meV, which seems reasonably consistent with the estimates of 31-32 meV in the present work.…”

Section: Hole Drift-mobility Measurements In Microcrystalline Siliconmentioning

confidence: 99%

Hole drift-mobility measurements in microcrystalline silicon

Dylla

Finger

Schiff

2005

Applied Physics Letters

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We have measured transient photocurrents on several p-i-n solar cells based on microcrystalline silicon. For two of these samples, we were able to obtain conclusive hole drift-mobility measurements. Despite the predominant crystallinity of these samples, temperature-dependent measurements were consistent with an exponential-bandtail trapping model for transport, which is usually associated with noncrystalline materials. We estimated valence bandtail widths of about 31meV and hole band mobilities of 1–2cm2∕Vs. The measurements support mobility-edge transport for holes in these microcrystalline materials, and broaden the range of materials for which mobility-edge transport corresponds to an apparently universal band mobility of order 1cm2∕Vs.

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Interpretation of Transient Photocurrents in Coplanar and Sandwich PIN Microcrystalline Silicon Structures

Cited by 6 publications

References 14 publications

Carrier drift-mobilities and solar cell models for amorphous and nanocrystalline silicon

Carrier drift-mobilities and solar cell models for amorphous and nanocrystalline silicon

Determination of the mobility gap of intrinsic μc-Si:H in p-i-n solar cells

Hole drift-mobility measurements in microcrystalline silicon

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