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

• Published in: Nanoscale research letters 2015-03, Vol.10 (1), p.137-137, Article 137
• Main Authors: Xiang, Yuren, Zhou, Chunlan, Jia, Endong, Wang, Wenjing
• Format: Article
• Language: English
• Subjects: 2nd International Conference on ALD Applications & 3rd China ALD conference; Chemistry and Materials Science; Materials Science; Molecular Medicine; Nano Express; Nanochemistry; Nanoscale Science and Technology; Nanotechnology; Nanotechnology and Microengineering
• ISSN: 1931-7573; 1556-276X
• DOI: 10.1186/s11671-015-0798-2

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)/Al 2 O 3 stacks on KOH solution-polished n-type solar grade mono-silicon(100) wafers. For the Al 2 O 3 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)/Al 2 O 3 stacks by a non-contact corona C-V technique. After the fabrication of a-Si:H(i)/Al 2 O 3 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 Al 2 O 3 deposition on Al 2 O 3 single layers and a-Si:H(i)/Al 2 O 3 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.