Microcrystalline Silicon in a-SI:H Based Multljunction Solar Cells

Yang, Lei; Chen, L.; Wiedeman, S.; Catalano, A.

doi:10.1557/proc-283-463

Cited by 30 publications

(10 citation statements)

References 5 publications

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“…1,7,27 We also observed this phenomenon for the films grown at different frequencies on glass and a-Si:H. In Fig. 6 the thickness dependence of the conductivity of cSi:H films on glass and a-Si:H is shown for material prepared at two different plasma excitation frequencies.…”

Section: B Electrical Conductivitysupporting

confidence: 53%

“…The use of microcrystalline silicon in this recombination junction leads to a significant improvement of the device. 1 A further important application of c-Si:H will be as an active layer in stacked solar cells or as an all-thin-crystalline solar cell where an improved red response and a presumably higher stability with respect to a-Si:H are the key issues. 2 There are two major technical problems in the engineering of microcrystalline silicon: ͑1͒ a very low deposition rate and ͑2͒ a strongly substrate dependent nucleation behavior.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Optical and transport studies on thin microcrystalline silicon films prepared by very high frequency glow discharge for solar cell applications

Tzolov

Finger

Carius

et al. 1997

Journal of Applied Physics

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Magnetocapacitance of an electrically tunable silicene device Appl. Phys. Lett. 101, 132412 (2012) Tuning luminescence properties of silicon nanocrystals by lithium doping J. Appl. Phys. 112, 064322 (2012) Features of temperature dependence of contact resistivity in ohmic contacts on lapped n-Si J. Appl. Phys. 112, 063703 (2012) Intense green and red upconversion emission of Er3+,Yb3+ co-doped CaZrO3 obtained by a solution combustion reaction J. Appl. Phys. 112, 063105 (2012) Low-frequency Raman scattering from Si/Ge nanocrystals in different matrixes caused by acoustic phonon quantizationThe initial growth stage of phosphorus doped microcrystalline silicon films prepared by plasma enhanced chemical vapor deposition with different plasma excitation frequencies in the range 13.56-116 MHz was studied by Raman and infrared spectroscopy, optical transmission and reflection, and conductivity measurements. The sensitivity of Raman spectroscopy and optical reflection on Si crystallites in the initial growth regime is compared and optical reflection at 4.5 eV is proposed as an easy and reliable tool for this investigation. While the crystallite formation on amorphous silicon substrates at 13.56 MHz is delayed in comparison with glass, SiO 2 and chromium substrates, nucleation of the crystalline phase on amorphous silicon is found to be greatly enhanced at higher plasma excitation frequencies. On the other hand, for deposition on glass, SiO 2 , and chromium at frequencies equal to or higher than 70 MHz, increased porosity is found in the initial growth region. The results are interpreted within a model that suggests a conelike initial formation of the silicon crystallites and a higher etching rate of disordered material at high plasma excitation frequencies. In addition, the extension of the process of crystallite formation from the film-plasma interface into a growth zone more than 10 nm deep is proposed. The application of the microcrystalline silicon layers prepared at high plasma excitation frequency is demonstrated in amorphous silicon based tandem solar cells.

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Section: B Electrical Conductivitysupporting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Optical and transport studies on thin microcrystalline silicon films prepared by very high frequency glow discharge for solar cell applications

Tzolov

Finger

Carius

et al. 1997

Journal of Applied Physics

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show abstract

“…1 -The absorption coefficient was calculated based on dualbeam transmittance measurements on a Cary, Inc. spectrophotometer and an awLiliary measurement of the thickness using a mechanical profilometer. For comparison purposes we have also shown literature curves (Yang, Chen, Wiedeman, and Catalano, 1993) for the absorption cuefficients for severalp+ materials currently used in a-Si:H based cells.…”

Section: Our Films Werementioning

confidence: 99%

Research on high-band-gap materials and amorphous-silicon-based solar cells. Annual subcontract report, May 15, 1994--May 14, 1995

Schiff¹,

Gu²,

Lin³

et al. 1995

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“…Alternatively, at least one of the n ϩ , p ϩ layers should be microcrystalline to achieve the same objective. [2][3][4][5][6] It has also been suggested that electrons from the n ϩ side and holes from the p ϩ side are partly driven towards this junction under the influence of the electric field in the respective subcells; and partly ''tunnel'' towards this junction against the high opposing n ϩ /p ϩ field. Computer simulation of such structures 1,7 has shown that conduction band edge grading of the subcell on the n ϩ side and valence band edge grading of the subcell on the p ϩ side, to simulate the real tunneling of electrons and holes, respectively, to the junction region are essential to simulate the high V oc and FF of tandem solar cells.…”

Section: Introductionmentioning

confidence: 99%

Hole diffusion at the recombination junction of thin film tandem solar cells and its effect on the illuminated current–voltage characteristic

Palit

Dasgupta

Ray

et al. 2000

Journal of Applied Physics

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Computer simulation of experimental current density–voltage (J–V) and quantum efficiency characteristics of thin film p1-i1-n1-p2 structures and of double junction solar cells (p1-i1-n1-p2-i2-n2), has been used to understand the hole transport mechanisms near the np “tunnel” junction between two subcells of a multijunction structure. Two different types of p layers at the junction have been studied: (i) hydrogenated microcrystalline silicon (μc-Si:H) and (ii) hydrogenated amorphous silicon carbide (a-SiC:H). There is a striking difference between the experimental J–V characteristics for the p1-i1-n1-p2 structures, with case (i) having a fairly high fill factor (FF) and conversion efficiency (η), as against a very low FF and η in case (ii). Although the difference is much smaller for double junction cells employing these two types of materials as the p layer at the junction, the fill factor of the cell employing μc-Si:H is about 8% higher. Analysis of transport properties as a function of position by computer modeling reveals that the main difference in behavior between the two cases is due to the much higher free hole population in the p layer at the junction when it is microcrystalline; which in turn, is a direct consequence of the lower activation energy for this case. We also learn that not only tunneling and the electric field in the bottom subcell, but also diffusion, plays a major role in pushing the holes produced in it by the incident light towards the recombination layer at the junction; and thereby helps improve cell performance, especially its fill factor. We conclude that the p layer at the junction should have a high free hole density (low activation energy in the device), to attain an overall high fill factor and conversion efficiency. Another interesting inference is the fact that tunneling as transport mechanism for holes towards the junction is more important when the p layer at the junction is a-SiC:H than when it is microcrystalline, while diffusion plays a more prominent role in propelling holes towards the junction in the latter case.

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Microcrystalline Silicon in a-SI:H Based Multljunction Solar Cells

Cited by 30 publications

References 5 publications

Optical and transport studies on thin microcrystalline silicon films prepared by very high frequency glow discharge for solar cell applications

Optical and transport studies on thin microcrystalline silicon films prepared by very high frequency glow discharge for solar cell applications

Research on high-band-gap materials and amorphous-silicon-based solar cells. Annual subcontract report, May 15, 1994--May 14, 1995

Hole diffusion at the recombination junction of thin film tandem solar cells and its effect on the illuminated current–voltage characteristic

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