Morphology and Hydrogen in Passivating Amorphous Silicon Layers

Gerke, Sebastian; Becker, Hans‐Werner; Rogalla, Detlef; Hahn, Giso; Job, R.; Terheiden, Barbara

doi:10.1016/j.egypro.2015.07.112

Cited by 8 publications

(12 citation statements)

References 20 publications

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“…Perf01ming them1al treatment Te.ffdecreases as described in [18) and is fotmd to be > 1 ms after 100 h. Due to the thetmal treatment, hydrogen effuses out of the layer, leavmg behind WlSaturated danglit1g bonds which act as defects limiting minority carrier lifetime.…”

Section: Validationmentioning

confidence: 99%

“…All samples discussed in this study were based on plasma enhanced chemical vapor (PECV) deposited (i) a-Si:H with a columnar morphology [17][18][19]. A colUlllilar mmphology was chosen as investigations pointed out that there is an appreciable decrease in the passivation quality of colUlllilru· grown (i) a-Si:H during thermal treatment [18,19].…”

Section: Sample Preparationmentioning

confidence: 99%

“…A colUlllilar mmphology was chosen as investigations pointed out that there is an appreciable decrease in the passivation quality of colUlllilru· grown (i) a-Si:H during thermal treatment [18,19].…”

Section: Sample Preparationmentioning

confidence: 99%

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Capacitance–voltage spectroscopy and analysis of dielectric intrinsic amorphous silicon thin films

Gerke

Micard

Job

et al. 2016

Phys. Status Solidi C

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Capacitance-voltage (CV) spectroscopy of classic metalinsulator-semiconductors (MIS) using insulating oxides as well as highly passivating intrinsic and hydrogenated amorphous silicon ((i) a-Si:H) has been discussed extensively in literature, particularly with regard to photovoltaic applications. Imperfectly passivating as well as thermal or light-induced degraded (i) a-Si:H exhibits a reduced passivation quality and an increased defectbased shunt conductivity. These properties cannot be accounted for by classical CV spectroscopy as described in literature for insulating oxides or highly passivating (i) a-Si:H. To characterize such imperfectly passivating or degraded (i) a-Si:H thin films by CV spectroscopy, the required MIS samples have to be prepared following special design rules. Design rules were defined on the base of electric field FEM investigations and empirically validated. In combination with an adapted approach to calculate the number of defects (N D ) CV spectrometry becomes a more reliable analytic tool to describe imperfectly passivating as well as degraded (i) a-Si:H.

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Section: Validationmentioning

confidence: 99%

Section: Sample Preparationmentioning

confidence: 99%

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Capacitance–voltage spectroscopy and analysis of dielectric intrinsic amorphous silicon thin films

Gerke

Micard

Job

et al. 2016

Phys. Status Solidi C

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“…Assuming a stopping power of the amorphous layer of 1.38 keV/nm (Ref. [39]), a corresponding increase of the beam energy enables measuring a hydro gen depth profile. More common than NRRA are secondary ion mass spectrometry (SIMS) measurements, because this technique allows a simultaneous detection of further elements included in a sample [43,44] SIMS mea surements were performed with a sector field instrument (Cameca ims5f) using optimized conditions for the detection of boron in silicon.…”

Section: Hydrogen Depth Profiling and Bonding Structuresmentioning

confidence: 99%

“…[3,39,40,52]), the morphology of an a Si:H layer exhibits a non columnar structure during CVD (chemical vapor deposi tion) and a columnar one during a PVD (physical vapor deposition) process. If the sticking coefficient of the used process gas mix is high, surface mobility of the Si atoms is low.…”

Section: Microscopic Investigationsmentioning

confidence: 99%

Influence of post-hydrogenation upon electrical, optical and structural properties of hydrogen-less sputter-deposited amorphous silicon

Gerke

Becker²,

Rogalla³

et al. 2016

Thin Solid Films

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a b s t r a c t a r t i c l e i n f oAmorphous silicon (a Si) is common in the production of technical devices and can be deposited by several techniques. In this study intrinsic and doped, hydrogen less amorphous silicon films are RF magnetron sputter deposited and post hydrogenated in a remote hydrogen plasma reactor at a temperature of 370°C. Secondary ion mass spectrometry of a boron doped (p) a Si layer shows that the concentration of dopants in the sputtered layer becomes the same as present in the sputter target. Improved surface passivation of phosphorous doped 5 Ω cm, FZ, (n) c Si can be achieved by post hydrogenation yielding a minority carrier lifetime of~360 μs finding an optimum for~40 nm thin films, deposited at 325°C. This relatively low minority carrier lifetime indicates high disorder of the hydrogen less sputter deposited amorphous network. Post hydrogenation leads to a decrease of the number of localized states within the band gap. Optical band gaps (Taucs gab as well as E 04 ) can be determined to~1.88 eV after post hydrogenation. High resolution transmission electron microscopy and optical Raman investigations show that the sputtered layers are amorphous and stay like this during post hydrogenation. As a consequence of the missing hydrogen during deposition, sputtered a Si forms a rough surface compared to CVD a Si. Atomic force microscopy points out that the roughness decreases by up to 25% during post hydrogenation. Nuclear resonant reaction analysis permits the investigation of hydrogen depth profiles and allows determining the diffusion coefficients of several post hydrogenated samples from of a model developed within this work. A dependency of diffusion coefficients on the duration of post hydrogenation indicates trapping diffusion as the main diffusion mechanism. Additional Fourier transform infrared spectroscopy measurements show that hardly any interstitial hydrogen exists in the post hydrogenated a Si layers. The results of this study open the way for further hydrogen diffusion experiments which require an initially unhydrogenated drain layer.

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Dielectric surface passivation for silicon solar cells: A review

Bonilla

Hoex

Hamer

et al. 2017

Physica Status Solidi (a)

236

161

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This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Silicon wafer solar cells continue to be the leading photovoltaic technology, and in many places are now providing a substantial portion of electricity generation. Further adoption of this technology will require processing that minimises losses in device performance. A fundamental mechanism for efficiency loss is the recombination of photo-generated charge carriers at the unavoidable cell surfaces. Dielectric coatings have been shown to largely prevent these losses through a combination of different passivation mechanisms. This review aims to provide an overview of the dielectric passivation coatings developed in the past two decades using a standardised methodology to characterise the metrics of surface recombination across all techniques and materials. The efficacy of a large set of materials and methods has been evaluated using such metrics and a discussion on the current state and prospects for further surface passivation improvements is provided.

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Morphology and Hydrogen in Passivating Amorphous Silicon Layers

Cited by 8 publications

References 20 publications

Capacitance–voltage spectroscopy and analysis of dielectric intrinsic amorphous silicon thin films

Capacitance–voltage spectroscopy and analysis of dielectric intrinsic amorphous silicon thin films

Influence of post-hydrogenation upon electrical, optical and structural properties of hydrogen-less sputter-deposited amorphous silicon

Dielectric surface passivation for silicon solar cells: A review

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