Device grade microcrystalline silicon owing to reduced oxygen contamination

Torres, P.; Meier, J.; Flückiger, R.; Kroll, U.; Selvan, J. A. Anna; Keppner, H.; Shah, A.; Littelwood, S. D.; Kelly, I.; Giannoulès, P.

doi:10.1063/1.117440

Cited by 181 publications

(91 citation statements)

References 9 publications

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“…However, similar studies as in [19] should be of interest for material with variation of I c RS . Another source of instability with influence on electronic conductivity, which keeps being reported, are oxygen donors in mc-Si:H [31,32]. The various types of oxygen donors in crystalline silicon have been and are still being studied in great detail [33].…”

Section: Discussionmentioning

confidence: 99%

Stability of microcrystalline silicon for thin film solar cell applications

Finger¹,

Carius²,

Dylla³

et al. 2003

IEE Proc., Circuits Devices Syst.

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The development of microcrystalline silicon (mc-Si:H) for solar cells has made good progress with efficiencies better than those of amorphous silicon (a-Si:H) devices. Of particular interest is the absence of light-induced degradation in highly crystalline mc-Si:H. However, the highest efficiencies are obtained with material which may still include a-Si:H regions and lightinduced changes may be expected in such material. On the other hand, material of high crystallinity is susceptible to in-diffusion of atmospheric gases which, through adsorption or oxidation, affect the electronic transport. Investigations are presented of such effects concerning the stability of mcSi:H films and solar cells prepared by plasma-enhanced chemical vapour deposition and hot wire chemical vapour deposition.

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Section: Discussionmentioning

confidence: 99%

Stability of microcrystalline silicon for thin film solar cell applications

Finger¹,

Carius²,

Dylla³

et al. 2003

IEE Proc., Circuits Devices Syst.

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“…The samples were deposited by the VHF-GD deposition technique at a plasma excitation frequency of 110 MHz using a gas purifier [6]. Thereby the ratio of silane flow over total gas flow [SiH 4 ]/[SiH 4 + H 2 ] was varied between 1.25% and 7.5%.…”

Section: Methodsmentioning

confidence: 99%

“…Even though all layers were produced using a gas purifier in order to prevent the incorporation of impurities [6], the microcrystalline materials deposited with high dilutions show a pronounced extrinsic behaviour (Fig. 2) as is usually obtained in the presence of [O] contaminants.…”

Section: Electrical Propertiesmentioning

confidence: 99%

Optical and Electrical Properties of Undoped Microcrystalline Silicon Deposited by the VHF-GD with Different Dilutions of Silane in Hydrogen

et al. 1996

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We show that the optical and electrical properties of microcrystalline silicon (µc-Si:H) deposited by the VHF-GD technique at 110 MHz can considerably be tuned by changing the dilution ratio of silane to hydrogen.With increasing silane dilution we observe enhanced optical absorption for energies below 2 eV due to the transition of the material from amorphous / microcrystalline mixture to a pure microcrystalline phase. Simultaneously, the light scattering and the defect absorption increases. Strong dilution also promotes the incorporation of impurities into the material, leading to a pronounced extrinsic behaviour as seen from the decrease of the activiation energy of the electrical conductivity.The electrical properties were investigated in the dark by the Time of Flight technique. We measured drift mobilities at room temperature which slightly increase with dilution, reaching values of 3 cm 2 /Vs for electrons and 1.2 cm 2 /Vs for holes. The ratio between electron and hole drift mobilities is found to be around 2 for all samples studied, similar to that of crystalline silicon.Furthermore, post-transient Time of Flight measurements revealed detrimental electron deep traps in low dilution material.

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“…The purifying technique: A gas purifier (oxygen getter) installed close to the reactor removes oxygen-containing impurities (8). Thereby, low dark conductivities and µc-Si:H single-junction solar cells with 7.7% efficiency could be obtained (6,11). The purifying technique can completely replace the compensation technique.…”

Section: "Mid-gap" Materialsmentioning

confidence: 99%

The “Micromorph” cell: a new way to high-efficiency-low-temperature crystalline silicon thin-film cell manufacturing?

Keppner¹,

Kroll²,

Torres³

et al. 1997

AIP Conference Proceedings

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Abstract. Hydrogenated microcrystalline Silicon (µc-Si:H) produced by the VHF-GD (Very High Frequency Glow Discharge) process can be considered to be a new base material for thin-film crystalline silicon solar cells. The most striking feature of such cells, in contrast to conventional amorphous silicon technology, is their stability under lightsoaking. With respect to crystalline silicon technology, their most striking advantage is their low process temperature (220°C). The so called "micromorph" cell contains such a µc-Si:H based cell as bottom cell, whereas the top-cell consists of amorphous silicon. A stable efficiency of 10.7% (confirmed by ISE Freiburg) is reported in this paper.At present, all solar cell concepts based on thin-film crystalline silicon have a common problem to overcome: namely, too long manufacturing times. In order to help in solving this problem for the particular case of plasma-deposited µc-Si:H, results on combined argon /hydrogen dilution of the feedgas (silane) are presented. It is shown that rates as high as 9.4 Å/s can be obtained; furthermore, a first solar cell deposited with 8.7 Å/s resulted in an efficiency of 3.1%.

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Device grade microcrystalline silicon owing to reduced oxygen contamination

Cited by 181 publications

References 9 publications

Stability of microcrystalline silicon for thin film solar cell applications

Stability of microcrystalline silicon for thin film solar cell applications

Optical and Electrical Properties of Undoped Microcrystalline Silicon Deposited by the VHF-GD with Different Dilutions of Silane in Hydrogen

The “Micromorph” cell: a new way to high-efficiency-low-temperature crystalline silicon thin-film cell manufacturing?

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