Structural changes of<i>a</i>-Si:H films on crystalline silicon substrates during deposition

Neitzert, H. C.; Hirsch, W. C.; Kunst, M.

doi:10.1103/physrevb.47.4080

Cited by 26 publications

(11 citation statements)

References 4 publications

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“…This relaxation effect is still occurring for a-Si:H layers that are about 30 nm thick. 35 For i a-Si:H layer thickness increasing from 40 to 500 nm, we observe again an increase of N S with no variation in Q S as seen from Table I. This more defective interface may be induced by increasing mechanical stress at the c-Si/a-Si:H interface when growing such thick layers.…”

Section: Passivation By Intrinsic A-si:h Layerssupporting

confidence: 53%

Model for a-Si:H/c-Si interface recombination based on the amphoteric nature of silicon dangling bonds

2007

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The performance of many silicon devices is limited by electronic recombination losses at the crystalline silicon ͑c-Si͒ surface. A proper surface passivation scheme is needed to allow minimizing these losses. The surface passivation properties of amorphous hydrogenated silicon ͑a-Si:H͒ on monocrystalline Si wafers are investigated here. We introduce a simple model for the description of the surface recombination mechanism based on recombination through amphoteric defects, i.e. dangling bonds, already established for bulk a-Si:H. In this model, the injection-dependent recombination at the a-Si:H/c-Si interface is governed by the density and the average state of charge of the amphoteric recombination centers. We show that with our surface recombination model, we can discriminate between the respective contribution of the two main mechanisms leading to improved surface passivation, which is achieved by ͑a͒ the minimization of the density of recombination centers and ͑b͒ the strong reduction of the density of one carrier type near the interface by field effect. We can thereafter reproduce the behaviors experimentally observed for the dependence of the surface recombination on the injection level on different wafers, i.e., of both p and n doping type as well as intrinsic. Finally, we are able to exploit the good surface passivation properties of our a-Si:H layers by fabricating flat heterojunction solar cells with open-circuit voltages exceeding 700 mV.

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Section: Passivation By Intrinsic A-si:h Layerssupporting

confidence: 53%

Model for a-Si:H/c-Si interface recombination based on the amphoteric nature of silicon dangling bonds

2007

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“…3(a), this phenomenon is not observable, confirming that, underneath the film-growth surface, in-situ defect annealing may occur. 25,26 In summary, a universal energy barrier for defect reduction is found. Its value is the same for a-Si:H bulk defects and a-Si:H/c-Si interface states, independent of film properties.…”

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confidence: 81%

Kinetics ofa-Si:H bulk defect anda-Si:H/c-Si interface-state reduction

2012

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Low-temperature annealing of hydrogenated amorphous silicon (a-Si:H) is investigated. An identical energy barrier is found for the reduction of deep defects in the bulk of a-Si:H films and at the interface such layers form with crystalline Si (c-Si) surfaces. This finding gives direct physical evidence that the defects determining a-Si:H/c-Si interface recombination are silicon dangling bonds and that also kinetically this interface has no unique features compared to the a-Si:H bulk.

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“…Con- sequently, it is crucial to control the properties of the aSi:H layers during deposition as accurately as possible [84]. Hydrogenated amorphous silicon layers have been studied in situ with various optical methods such as spectroscopic ellipsometry [64,85,86], Fourier-transform infrared (IR) spectroscopy [64], second-harmonic generation spectroscopy [70], and even carrier-lifetime measurements [87]. Since the properties of materials deposited by PEVCD are directly linked to the plasma properties, plasma diagnostics are very useful too, giving fundamental insight into deposition mechanisms.…”

Section: Substrates and Surface Preparationmentioning

confidence: 99%

High-efficiency Silicon Heterojunction Solar Cells: A Review

Wolf¹,

Descoeudres²,

Holman³

et al. 2012

Green

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Abstract. Silicon heterojunction solar cells consist of thin amorphous silicon layers deposited on crystalline silicon wafers. This design enables energy conversion efficiencies above 20% at the industrial production level. The key feature of this technology is that the metal contacts, which are highly recombination active in traditional, diffused-junction cells, are electronically separated from the absorber by insertion of a wider bandgap layer. This enables the record open-circuit voltages typically associated with heterojunction devices without the need for expensive patterning techniques. This article reviews the salient points of this technology. First, we briefly elucidate device characteristics. This is followed by a discussion of each processing step, device operation, and device stability and industrial upscaling, including the fabrication of solar cells with energyconversion efficiencies over 21%. Finally, future trends are pointed out.

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Structural changes ofa-Si:H films on crystalline silicon substrates during deposition

Cited by 26 publications

References 4 publications

Model for a-Si:H/c-Si interface recombination based on the amphoteric nature of silicon dangling bonds

Model for a-Si:H/c-Si interface recombination based on the amphoteric nature of silicon dangling bonds

Kinetics ofa-Si:H bulk defect anda-Si:H/c-Si interface-state reduction

High-efficiency Silicon Heterojunction Solar Cells: A Review

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