Low Surface Recombination Velocity using amorphous Silicon on industrial-type cleaned Surfaces

Gloger, Sebastian; Brinkmann, Nils; Terheiden, Barbara

doi:10.1016/j.egypro.2011.06.199

Cited by 10 publications

(9 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Several publications have discussed hydrogen depth profiles within a‐Si:H layers as measured by NRRA . NRR‐analyses in this study were carried out using the Dynamitron tandem accelerator located at the central unit for ion beams and radioisotopes at the University of Bochum.…”

Section: Methodsmentioning

confidence: 99%

“…To investigate the hydrogen diffusion in the a‐Si layer and its influence on structural, electrical and optical characteristics, the initially hydrogen‐free grown a‐Si is hydrogenated in a subsequent post‐hydrogenation step . This hydrogenation is carried out using a hydrogen remote plasma . The distribution of hydrogen as well as the related ongoing trap limited diffusion process is investigated by the measurement of hydrogen depth profiles by NRRA .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Model based prediction of the trap limited diffusion of hydrogen in post‐hydrogenated amorphous silicon

Gerke

Becker²,

Rogalla³

et al. 2016

Physica Rapid Research Ltrs

View full text Add to dashboard Cite

The diffusion of hydrogen within an hydrogenated amorphous silicon (a‐Si:H) layer is based on a trap limited process. Therefore, the diffusion becomes a self‐limiting process with a decreasing diffusion velocity for increasing hydrogen content. In consequence, there is a strong demand for accurate experimental determination of the hydrogen distribution. Nuclear resonant reaction analysis (NRRA) offers the possibility of a non‐destructive measurement of the hydrogen distribution in condensed matter like a‐Si:H thin films. However, the availability of a particle accelerator for NRR‐analysis is limited and the related costs are high. In comparison, Fourier transform infrared spectroscopy (FTIR) is also a common method to determine the total hydrogen content of an a‐Si:H layer. FTIR spectrometers are practical table‐top units but lack spatial resolution. In this study, an approach is discussed that greatly reduces the need for complex and expensive NRR‐analysis. A model based prediction of hydrogen depth profiles based on a single NRRA measurement and further FTIR measurements enables to investigate the trap limited hydrogen diffusion within a‐Si:H. The model is validated by hydrogen diffusion experiments during the post‐hydrogenation of hydrogen‐free sputtered a‐Si. The model based prediction of hydrogen depth profiles in a‐Si:H allows more precise design of experiments, prevents misinterpretations, avoids unnecessary NRRA measurements and thus saves time and expense. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Model based prediction of the trap limited diffusion of hydrogen in post‐hydrogenated amorphous silicon

Gerke

Becker²,

Rogalla³

et al. 2016

Physica Rapid Research Ltrs

View full text Add to dashboard Cite

show abstract

“…Gloger et al demonstrated that surface passivation of a c Si wafer by an (i) a Si:H layer, destroyed by a high temperature treatment, could be recovered by annealing in an atmosphere containing hydrogen radicals [20]. It can therefore be assumed that it is possible to achieve surface passivation by hydrogenating a hydrogen less a Si layer in a MIRHP (microwave induced remote hydrogen plasma) reactor [20].…”

Section: Introductionmentioning

confidence: 99%

“…It can therefore be assumed that it is possible to achieve surface passivation by hydrogenating a hydrogen less a Si layer in a MIRHP (microwave induced remote hydrogen plasma) reactor [20]. Analyzing surface passivation of c Si wafers starting from hydrogen less a Si layers allows investigation of hydrogen diffusion within the a Si layer and the corresponding influence of the amorphous network.…”

Section: Introductionmentioning

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

Self Cite

View full text Add to dashboard Cite

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.

show abstract

“…11 Recently, the passivation provided by as-deposited 7-nm-thick or 15-nm-thick intrinsic a-Si:H layers was demonstrated to improve upon performing a hydrogen plasma treatment, 12,13 and the passivation of 35-105-nm-thick a-Si:H layers was shown to recover after a high-peak-temperature processing step by annealing in an atmosphere consisting of molecular and atomic hydrogen. 14 We investigate here the possibility of restoring the passivation provided by thin, device-relevant intrinsic a-Si:H layers after high-temperature annealing. We apply hydrogen plasma treatments to rehydrogenate 6-20-nm-thick a-Si:H layers after 20 min annealing at 300-600 C. We also integrate the dehydrogenation and rehydrogenation (i.e., annealing and hydrogen plasma treatment) processes into the fabrication of complete SHJ solar cells to demonstrate compatibility with devices.…”

mentioning

confidence: 99%

Plasma-initiated rehydrogenation of amorphous silicon to increase the temperature processing window of silicon heterojunction solar cells

Shi

Boccard

Holman

2016

Applied Physics Letters

View full text Add to dashboard Cite

The dehydrogenation of intrinsic hydrogenated amorphous silicon (a-Si:H) at temperatures above approximately 300 °C degrades its ability to passivate silicon wafer surfaces. This limits the temperature of post-passivation processing steps during the fabrication of advanced silicon heterojunction or silicon-based tandem solar cells. We demonstrate that a hydrogen plasma can rehydrogenate intrinsic a-Si:H passivation layers that have been dehydrogenated by annealing. The hydrogen plasma treatment fully restores the effective carrier lifetime to several milliseconds in textured crystalline silicon wafers coated with 8-nm-thick intrinsic a-Si:H layers after annealing at temperatures of up to 450 °C. Plasma-initiated rehydrogenation also translates to complete solar cells: A silicon heterojunction solar cell subjected to annealing at 450 °C (following intrinsic a-Si:H deposition) had an open-circuit voltage of less than 600 mV, but an identical cell that received hydrogen plasma treatment reached a voltage of over 710 mV and an efficiency of over 19%.

show abstract

Low Surface Recombination Velocity using amorphous Silicon on industrial-type cleaned Surfaces

Cited by 10 publications

References 6 publications

Model based prediction of the trap limited diffusion of hydrogen in post‐hydrogenated amorphous silicon

Model based prediction of the trap limited diffusion of hydrogen in post‐hydrogenated amorphous silicon

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

Plasma-initiated rehydrogenation of amorphous silicon to increase the temperature processing window of silicon heterojunction solar cells

Contact Info

Product

Resources

About