New Hydrogen Distribution in<i>a</i>-Si:H: An NMR Study

Wu, Yue; Stephen, J. Todd; Han, Daxing; Rutland, J; Crandall, Richard S.; Mahan, A. H.

doi:10.1103/physrevlett.77.2049

Cited by 112 publications

(86 citation statements)

References 12 publications

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“…A different activation energy for electron mobility points to different kinds of traps [88][89][90] or traps residing in slightly different-structured material. This last idea might be comparable with results on hydrogen in a-Si:H obtained with NMR on highly structured HW-CVD a-Si:H, for which a non-homogeneous distribution of hydrogen throughout the material was found [61]. Dangling bonds on void surfaces or within a compact Si network will result in other activation energies for the release of trapped electrons.…”

Section: Measurementssupporting

confidence: 71%

“…Furthermore, it is interesting to note that a smaller hydrogen content does not mean that there are more defects in the material. The lower hydrogen content is a striking similarity with HW-CVD material [61]. Mahan et al [60] showed differences in opto-electronic properties compared with RF-PECVD and reported better structural order of the HW-CVD material.…”

Section: Measurementsmentioning

confidence: 84%

“…Atomic hydrogen influences the weak bond concentration [74] resulting in structural relaxation [61,75,76] due to the energy that is released by this interaction. The influence of the H-flux on the quality of the material is discussed in an extended kinetic growth model by Van de Sanden et al [77] and by numerous other groups [e.g.…”

Section: Measurementsmentioning

confidence: 99%

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Integration of Expanding Thermal Plasma deposited Hydrogenated Amorphous Silicon in Solar Cells

et al. 2002

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A cascaded arc expanding thermal plasma is used to deposit intrinsic hydrogenated amorphous silicon at growth rates between 0.2 and 3 nm/s. Incorporation into a single junction p-i-n solar cell resulted in an initial efficiency of 6.7%, whereas all the optical and initial electrical properties of the individual layers are comparable with RF-PECVD deposited films. In this cell the intrinsic layer was deposited at 0.85 nm/s and at a deposition temperature of 250°C, which is the temperature limit for growing the p-i-n sequence. The cell efficiency is limited by the fill factor and using a buffer layer at the p-i interface deposited with RF-PECVD at low growth rate can increase this. The increase in fill factor is a result of a lower initial defect density near the p-i interface then obtained with the expanding thermal plasma, resulting in better charge carrier collection. To use larger growth rates, while maintaining the material properties, higher deposition temperatures are required. Higher deposition temperatures result in a smaller optical bandgap for the intrinsic layer and deterioration of the p-type layer, resulting in a lower opencircuit voltage. First results on applying a buffer layer will also be presented.

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Section: Measurementssupporting

confidence: 71%

Section: Measurementsmentioning

confidence: 84%

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Integration of Expanding Thermal Plasma deposited Hydrogenated Amorphous Silicon in Solar Cells

et al. 2002

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“…High temperature a-Si:H, deposited by the hot wire (HW) technique, has demonstrated very different structural and electronic properties, including a reduced Staebler-Wronski metastability, a different H NMR 'signature', improved structural ordering, and a dramatic reduction in film internal friction, which until now had been thought to be unachievable for an amorphous material [1][2][3][4]. The additional possibility of depositing such materials at high deposition rates [5] has only added to its attractiveness as a candidate for incorporation into a solar cell structure.…”

Section: Introductionmentioning

confidence: 99%

H Out-Diffusion and Device Performance in n-i-p Solar Cells Utilizing High Temperature Hot Wire a-Si:H i-Layers

Mahan¹,

Iwaniczko²,

Wang³

et al. 1998

MRS Proc.

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. Hydrogen out-diffusion from the n/i interface region plays a major role in controlling the fill factor (FF) and resultant efficiency of n-i-p a-Si:H devices, with the i-layer deposited at high substrate temperatures by the hot wire technique. Modeling calculations have shown that a thin, highly defective layer at this interface, perhaps caused by significant H out-diffusion and incomplete lattice reconstruction, results in sharply lower device FFs due to the large voltage dropped across this defective layer. We have therefore employed buffer layers designed to retard this out-diffusion. We find that an increased H content, either in the n-layer or a thin intrinsic low temperature buffer layer, does not significantly retard this out-diffusion, as observed by SIMS H profiles on devices. However, if this low temperature buffer layer is thick enough, the out-diffusion is minimized, yielding nearly flat H profiles and a much improved device performance. We discuss this behavior in the context of the H chemical potentials and H diffusion coefficients in the high temperature, buffer, n-, and stainless steel substrate layers. Finally, we report a 9.8% initial active area device, fabricated at 16.5Å/s, using the insights obtained in this study. Light soaking data are also reported.

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“…Dengan teknik baru ini, Lapisan tipis yang dihasilkan mempunyai kualitas yang relatif lebih baik akibat dekomposisi silan pada permukaan filamen panas [8,9]. Selain itu teknik ini melibatkan parameterparameter deposisi yang relatif sedikit sehingga mudah dikontrol.…”

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Studi Optimasi Parameter Daya RF untuk Penumbuhan Lapisan Tipis Mikrokristal Silikon dengan Metode Hot Wire Cell PECVD

2005

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Abstrak. Metode Hot Wire Cell PECVD (Plasma Enhanced Chemical Vapor Deposition) telah berhasil dikembangkan untuk menumbuhkan lapisan tipis amorf silikon terhidrogenasi (a-Si:H) dengan konduktivitas yang relatif tinggi. Lapisan tipis a-Si:H ditumbuhkan di atas gelas corning 7059 pada temperatur filamen 800 o C. Gas silan (SiH 4 ) 10 % dalam gas hidrogen (H 2 ) digunakan sebagai sumber gas. Dalam metode hot wire cell PECVD, gas reaktan didekomposisi dengan filamen tungsten panas yang diletakkan diluar kedua elektroda dan paralel dengan system gas masukan. Dari hasil karakterisasi diperoleh bahwa laju deposisi meningkat dari 0,89 Å/s sampai 1,90 Å/s dengan meningkatnya daya rf dari 60 watt sampai 120 watt. Celah pita optik menurun dari 1,68 eV sampai 1,56 eV dengan meningkatnya daya rf dari 60 watt sampai 120 watt. Dari hasil foto SEM dan spektrum XRD memperlihatkan adanya transisi amorf ke mikrokristal pada daya rf 120 watt. Transisi amorf ke mikrokristal ditandai dengan berkurangnya fasa amorf dan adanya puncak difraksi pada orientasi kristal istimewa <111>. Konduktivitas gelap dan terang lapisan tipis µc-Si:H yang diperoleh sebesar 6,84x10 -6 S cm -1 dan 4,16x10 -4 S cm -1 . Abstract. The Hot Wire Cell PECVD method has been developed and successfully applied to grow the hydrogenated amorphous silicon (a-Si:H) thin films with a relatively high conductivity. The a-Si:H thin films were grown on the 7059 corning glass at a filament temperature of 800 o C. Ten percents silane (SiH 4 ) gas diluted in hydrogen (H 2 ) gas was used as gas source. In the hot wire cell PECVD method, reactant gases are decomposed as a result of reaction with a heated filament. The filament was placed parallelly with inlet gas system and outside of electrodes. The characterization results exhibited that the deposition rate increased from 1.02 Å/s to 1.90 Å/s with increasing the rf power from 80 watt to 120 watt. The optical bandgap decreased from 1.65 eV to 1.56 eV with increasing the rf power from 80 watt to 120 watt. The SEM image and the XRD

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New Hydrogen Distribution ina-Si:H: An NMR Study

Cited by 112 publications

References 12 publications

Integration of Expanding Thermal Plasma deposited Hydrogenated Amorphous Silicon in Solar Cells

Integration of Expanding Thermal Plasma deposited Hydrogenated Amorphous Silicon in Solar Cells

H Out-Diffusion and Device Performance in n-i-p Solar Cells Utilizing High Temperature Hot Wire a-Si:H i-Layers

Studi Optimasi Parameter Daya RF untuk Penumbuhan Lapisan Tipis Mikrokristal Silikon dengan Metode Hot Wire Cell PECVD

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