On light-induced effect in amorphous hydrogenated silicon

Guha, S.; Narasimhan, K. L.; Pietruszko, S.M.

doi:10.1063/1.328849

Cited by 133 publications

(47 citation statements)

References 12 publications

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“…Since the first observation of enhanced stability of a-Si:H films deposited with H 2 dilution [1] this technique has become the only tool available at the production level proven to result in a-Si:H solar cells with improved stability against light-soaking. However, the proper choice of plasma excitation frequency in combination with H 2 dilution has not yet been resolved satisfactorily.…”

Section: Introductionmentioning

confidence: 99%

Comparison of VHF, RF and Dc Plasma Excitation for a-Si:H Deposition with Hydrogen Dilution

et al. 1998

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A comparative study of DC, RF and VHF excitation for the plasma enhanced chemical vapor deposition (PECVD) of intrinsic layers of a-Si:H is presented, with special emphasis on the effects of hydrogen dilution. Growth rates at comparable plasma power, for substrate temperatures between 100°C and 300°C and for various H 2 dilution ratios are presented, along with optical bandgap, H content, and electronic transport properties in the light-soaked state.H 2 strongly reduces the growth rate for all techniques. The growth rate for the highest H 2 dilution ratio is approximately four times higher for VHF than for DC or RF excitation. In all three cases increasing the substrate temperature reduces the optical gap and the H content C H . Raising the substrate temperature slightly enhances the stability of undiluted films. H 2 dilution increases the optical gap for all three techniques. The H content of RF-and VHF-deposited samples increases with increasing H 2 dilution ratio, while in DC deposition it produces an initial drop of the H content, followed by an increase. In all three cases, H 2 dilution improves the electronic transport properties of the material by roughly a factor of two. The gain in stability is most pronounced for relatively small dilution; in the case of DC deposition, too strong a dilution even has an adverse effect on stability.

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Section: Introductionmentioning

confidence: 99%

Comparison of VHF, RF and Dc Plasma Excitation for a-Si:H Deposition with Hydrogen Dilution

et al. 1998

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“…The degradation and measurement procedures are described in more detail in [16]. The measurement confirms the enhanced stability against light-soaking for films deposited with hydrogen dilution [17]. In fact, the H 2 -diluted i-layers at T s =220°C have successfully been incorporated into a-Si:H/a-Si:H stacked cells and as top cells in micromorph tandem cells resulting in stabilized efficiencies of 9% [2] and 10.7% [1] respectively.…”

Section: Electronical Properties and Degradation Behaviormentioning

confidence: 60%

High-Ts amorphous top cells for increased top cell currents in micromorph tandem cells

Platz

Hof

Fischer

et al. 1998

Solar Energy Materials and Solar Cells

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In the present paper, the authors discuss the application of amorphous p-i-n solar cells containing i-layers which are deposited at high substrate temperatures as top cells in amorphous/microcrystalline tandem ("micromorph") solar cells. Increasing the substrate temperature for the deposition of intrinsic a-Si:H results in a reduced optical gap. The optical absorption is enhanced and thereby the current generation. A high current generation within a relatively thin amorphous top cell is very interesting in the context of micromorph tandem cells, where the amorphous top cell should contribute a current of at least 13mA/cm 2 for a total cell current density of 26mA/cm 2 .A detailed study is presented of the intrinsic material deposited by VHF-GD at 70 MHz at substrate temperatures between 220°C and 360°C, including samples deposited from hydrogen-diluted silane plasmas. The stability of the films against light soaking is investigated employing the µ 0 τ 0 parameter, which has been shown to be directly correlated to the cell performance.The paper discusses in detail the technological problems arising from the insertion of ilayers deposited at high substrate temperatures into solar cells. These problems are specially pronounced in the case of cells in the p-i-n (superstrate) structure. The authors demonstrate that an appropriate interface layer at the p/i-interface can largely reduce the detrimental effects of i-layer deposition at high temperatures.Finally, the application of such optimized high-temperature amorphous cells as (a) bottom cells in a-Si:H/a-Si:H stacked cells and (b) as top cells in micromorph tandem cells is discussed. Current densities of 13mA/cm 2 in the top cell are available with a top cell i-layer thickness of only 250nm. The potential of such top cells for raising the stabilized efficiency of micromorph tandem cells is discussed.

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“…Strong hydrogen dilution of the silane gas mixture during a-Si deposition has been found to reduce the density of defect states and improve the stability of the material against light-soaking effects [110][111][112]. Solar cells with i-layers deposited using strong H 2 dilution show improved performance and stability [113,114].…”

Section: Hydrogen Dilutionmentioning

confidence: 99%

Amorphous Silicon–Based Solar Cells

Deng¹,

Schiff²

2003

Handbook of Photovoltaic Science and Engineering

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On light-induced effect in amorphous hydrogenated silicon

Abstract: Amorphous silicon films prepared by a discharge of 10% SiH4-90% H2 mixture are shown to have properties comparable to those prepared from 100% SiH4. These films are found to be quite stable against prolonged light exposure.

Cited by 133 publications

References 12 publications

Comparison of VHF, RF and Dc Plasma Excitation for a-Si:H Deposition with Hydrogen Dilution

Comparison of VHF, RF and Dc Plasma Excitation for a-Si:H Deposition with Hydrogen Dilution

High-Ts amorphous top cells for increased top cell currents in micromorph tandem cells

Amorphous Silicon–Based Solar Cells

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