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Oxidation precursor dependence of atomic layer deposited Al2O3 films in a-Si:H(i)/Al2O3 surface passivation stacks.

Xiang Y, Zhou C, Jia E, Wang W - Nanoscale Res Lett (2015)

Bottom Line: For the Al2O3 film deposition, both thermal atomic layer deposition (T-ALD) and plasma enhanced atomic layer deposition (PE-ALD) were used.Combining these results with an X-ray photoelectron spectroscopy analysis, we discussed the influence of an oxidation precursor for ALD Al2O3 deposition on Al2O3 single layers and a-Si:H(i)/Al2O3 stack surface passivation from field-effect passivation and chemical passivation perspectives.In addition, the influence of the stack fabrication process on the a-Si film structure was also discussed in this study.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Solar Thermal Energy and Photovoltaic System, Institute of Electrical Engineering, Chinese Academy of Sciences, No. 6 Beiertiao, Zhongguancun, Beijing, 100190 China.

ABSTRACT
In order to obtain a good passivation of a silicon surface, more and more stack passivation schemes have been used in high-efficiency silicon solar cell fabrication. In this work, we prepared a-Si:H(i)/Al2O3 stacks on KOH solution-polished n-type solar grade mono-silicon(100) wafers. For the Al2O3 film deposition, both thermal atomic layer deposition (T-ALD) and plasma enhanced atomic layer deposition (PE-ALD) were used. Interface trap density spectra were obtained for Si passivation with a-Si films and a-Si:H(i)/Al2O3 stacks by a non-contact corona C-V technique. After the fabrication of a-Si:H(i)/Al2O3 stacks, the minimum interface trap density was reduced from original 3 × 10(12) to 1 × 10(12) cm(-2) eV(-1), the surface total charge density increased by nearly one order of magnitude for PE-ALD samples and about 0.4 × 10(12) cm(-2) for a T-ALD sample, and the carrier lifetimes increased by a factor of three (from about 10 μs to about 30 μs). Combining these results with an X-ray photoelectron spectroscopy analysis, we discussed the influence of an oxidation precursor for ALD Al2O3 deposition on Al2O3 single layers and a-Si:H(i)/Al2O3 stack surface passivation from field-effect passivation and chemical passivation perspectives. In addition, the influence of the stack fabrication process on the a-Si film structure was also discussed in this study.

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Related in: MedlinePlus

Effective lifetime for single-side a-Si:H capped Si before and after Al2O3deposited. The Al2O3 films were deposited on PE-SA-1 and PE-SA-2 using PE-ALD at 200°C. The Al2O3 films were deposited on T-SA-1 using T-ALD at 200°C. After Al2O3 film deposition, the samples were annealed at 450°C for 10 min in air.
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Fig6: Effective lifetime for single-side a-Si:H capped Si before and after Al2O3deposited. The Al2O3 films were deposited on PE-SA-1 and PE-SA-2 using PE-ALD at 200°C. The Al2O3 films were deposited on T-SA-1 using T-ALD at 200°C. After Al2O3 film deposition, the samples were annealed at 450°C for 10 min in air.

Mentions: Figure 6 shows that the effective minority carrier lifetimes of the a-Si:H(i)/Al2O3 stack samples increase by a factor of three (from about 10 μs to about 30 μs) compared with only a-Si film passivation samples. The increases in the effective minority carrier lifetime mean that the chemical passivation or field-effect passivation improved, which are dominated by Extended-Shockley-Read-Hall recombination at the Si surface. In this case after capping with Al2O3 films, the reduction of average Dit and the increase of negative charges weaken the trap effect of defects and reduce the interface recombination to improve the effective minority carrier lifetime. From the data above, a-Si:H(i)/Al2O3 stack also shows a good thermal stability at 450°C that can extend the a-Si:H(i) film application field in the solar cell fabrication.Figure 6


Oxidation precursor dependence of atomic layer deposited Al2O3 films in a-Si:H(i)/Al2O3 surface passivation stacks.

Xiang Y, Zhou C, Jia E, Wang W - Nanoscale Res Lett (2015)

Effective lifetime for single-side a-Si:H capped Si before and after Al2O3deposited. The Al2O3 films were deposited on PE-SA-1 and PE-SA-2 using PE-ALD at 200°C. The Al2O3 films were deposited on T-SA-1 using T-ALD at 200°C. After Al2O3 film deposition, the samples were annealed at 450°C for 10 min in air.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385324&req=5

Fig6: Effective lifetime for single-side a-Si:H capped Si before and after Al2O3deposited. The Al2O3 films were deposited on PE-SA-1 and PE-SA-2 using PE-ALD at 200°C. The Al2O3 films were deposited on T-SA-1 using T-ALD at 200°C. After Al2O3 film deposition, the samples were annealed at 450°C for 10 min in air.
Mentions: Figure 6 shows that the effective minority carrier lifetimes of the a-Si:H(i)/Al2O3 stack samples increase by a factor of three (from about 10 μs to about 30 μs) compared with only a-Si film passivation samples. The increases in the effective minority carrier lifetime mean that the chemical passivation or field-effect passivation improved, which are dominated by Extended-Shockley-Read-Hall recombination at the Si surface. In this case after capping with Al2O3 films, the reduction of average Dit and the increase of negative charges weaken the trap effect of defects and reduce the interface recombination to improve the effective minority carrier lifetime. From the data above, a-Si:H(i)/Al2O3 stack also shows a good thermal stability at 450°C that can extend the a-Si:H(i) film application field in the solar cell fabrication.Figure 6

Bottom Line: For the Al2O3 film deposition, both thermal atomic layer deposition (T-ALD) and plasma enhanced atomic layer deposition (PE-ALD) were used.Combining these results with an X-ray photoelectron spectroscopy analysis, we discussed the influence of an oxidation precursor for ALD Al2O3 deposition on Al2O3 single layers and a-Si:H(i)/Al2O3 stack surface passivation from field-effect passivation and chemical passivation perspectives.In addition, the influence of the stack fabrication process on the a-Si film structure was also discussed in this study.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Solar Thermal Energy and Photovoltaic System, Institute of Electrical Engineering, Chinese Academy of Sciences, No. 6 Beiertiao, Zhongguancun, Beijing, 100190 China.

ABSTRACT
In order to obtain a good passivation of a silicon surface, more and more stack passivation schemes have been used in high-efficiency silicon solar cell fabrication. In this work, we prepared a-Si:H(i)/Al2O3 stacks on KOH solution-polished n-type solar grade mono-silicon(100) wafers. For the Al2O3 film deposition, both thermal atomic layer deposition (T-ALD) and plasma enhanced atomic layer deposition (PE-ALD) were used. Interface trap density spectra were obtained for Si passivation with a-Si films and a-Si:H(i)/Al2O3 stacks by a non-contact corona C-V technique. After the fabrication of a-Si:H(i)/Al2O3 stacks, the minimum interface trap density was reduced from original 3 × 10(12) to 1 × 10(12) cm(-2) eV(-1), the surface total charge density increased by nearly one order of magnitude for PE-ALD samples and about 0.4 × 10(12) cm(-2) for a T-ALD sample, and the carrier lifetimes increased by a factor of three (from about 10 μs to about 30 μs). Combining these results with an X-ray photoelectron spectroscopy analysis, we discussed the influence of an oxidation precursor for ALD Al2O3 deposition on Al2O3 single layers and a-Si:H(i)/Al2O3 stack surface passivation from field-effect passivation and chemical passivation perspectives. In addition, the influence of the stack fabrication process on the a-Si film structure was also discussed in this study.

No MeSH data available.


Related in: MedlinePlus