Improvement of grain size and deposition rate of microcrystalline silicon by use of very high frequency glow discharge

Finger, F.; Hapke, P.; Luysberg, M.; Carius, R.; Wagner, H.; Scheib, M.

doi:10.1063/1.112604

Cited by 157 publications

(57 citation statements)

References 10 publications

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“…1,3,4 With an independent bias on this electrode with respect to the grounded substrate, ion energies can be controllably reduced. Other effective methods to reduce ion energies while maintaining high deposition rates are ͑i͒ very high frequency ͑VHF͒ excitation of the discharge, where lower peak-to-peak voltages for a given discharge power result in lower maximum-ion energies, [5][6][7][8][9] and ͑ii͒ high working pressure ͑p depo ͒ with an increased discharge power, where ion energies are reduced by multiple collisions in the plasma sheath. [10][11][12] Recently, also combinations of VHF-PECVD and high working pressure have been investigated.…”

Section: Introductionmentioning

confidence: 99%

Microcrystalline silicon solar cells deposited at high rates

Mai

Klein

Carius

et al. 2005

Journal of Applied Physics

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Hydrogenated microcrystalline silicon ͑ c-Si:H͒ thin-film solar cells were prepared at high rates by very high frequency plasma-enhanced chemical vapor deposition under high working pressure. The influence of deposition parameters on the deposition rate ͑R D ͒ and the solar cell performance were comprehensively studied in this paper, as well as the structural, optical, and electrical properties of the resulting solar cells. Reactor-geometry adjustment was done to achieve a stable and homogeneous discharge under high pressure. Optimum solar cells are always found close to the transition from microcrystalline to amorphous growth, with a crystallinity of about 60%. At constant silane concentration, an increase in the discharge power did hardly increase the deposition rate, but did increase the crystallinity of the solar cells. This results in a shift of the c-Si:H/a-Si:H transition to higher silane concentration, and therefore leads to a higher R D for the optimum cells. On the other hand, an increase in the total flow rate at constant silane concentration did lead to a higher R D , but lower crystallinity. With this shift of the c-Si:H/a-Si:H transition at higher flow rates, the R D for the optimum cells decreased. A remarkable structure development along the growth axis was found in the solar cells deposited at high rates by a "depth profile" method, but this does not cause a deterioration of the solar cell performance apart from a poorer blue-light response. As a result, a c-Si:H single-junction p-i-n solar cell with a high efficiency of 9.8% was deposited at a R D of 1.1 nm/s.

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Section: Introductionmentioning

confidence: 99%

Microcrystalline silicon solar cells deposited at high rates

Mai

Klein

Carius

et al. 2005

Journal of Applied Physics

Self Cite

182

123

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“…A common deposition technique for this material is plasma-enhanced-chemical vapor deposition ͑PECVD͒ using high dilution of silane in hydrogen; this combination allows for deposition at rather low temperatures ͑150-300°C͒. Among the various forms of PECVD, the very high-frequency-glow discharge ͑VHF-GD͒ method has been shown to be particularly favorable for the growth of c-Si:H. [1][2][3][4] A problem often encountered with as-grown c-Si:H is its pronounced n-type character; this n-type character masked for a long time the excellent photovoltaic properties of this material. Nevertheless, this disturbing n-type character could, in recent work, 5,6 be compensated by ''microdoping''; thereby, ''midgap'' c-Si:H ͑Fermi level at midgap͒ was obtained and successfully implemented in a fully microcrystalline photovoltaic device.…”

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confidence: 99%

Device grade microcrystalline silicon owing to reduced oxygen contamination

Torres

Meier

Flückiger

et al. 1996

Applied Physics Letters

181

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As-deposited undoped microcrystalline silicon (μc-Si:H) has in general a pronounced n-type behavior. Such a material is therefore often not appropriate for use in devices, such as p-i-n diodes, as an active, absorbing i layer or as channel material for thin-film transistors. In recent work, on p-i-n solar cells, this disturbing n-type character had been successfully compensated by the ‘‘microdoping’’ technique. In the present letter, it is shown that this n-type behavior is mainly linked to oxygen impurities; therefore, one can replace the technologically delicate microdoping technique by a purification method, that is much easier to handle. This results in a reduction of oxygen impurities by two orders of magnitude; it has, furthermore a pronounced impact on the electrical properties of μc-Si:H films and on device performance, as well. Additionally, these results prove that the unwanted donor-like states within μc-Si:H are mainly due to extrinsic impurities and not to structural native defects.

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“…Looking at the deposition rates of µc-Si:H, the VHF-GD process in itself brings sofar at least some improvement, as reported by Finger et al (15). Attempts at obtaining yet higher deposition rates are described by Torres et al (16).…”

Section: Limits and Potential For Further Improvementsmentioning

confidence: 72%

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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Improvement of grain size and deposition rate of microcrystalline silicon by use of very high frequency glow discharge

Cited by 157 publications

References 10 publications

Microcrystalline silicon solar cells deposited at high rates

Microcrystalline silicon solar cells deposited at high rates

Device grade microcrystalline silicon owing to reduced oxygen contamination

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

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