Development of surface-textured hydrogenated ZnO: Al thin-films for μc-Si solar cells

Sung Ju Tark, Min Gu Kang, Sungeun Park, Ji Hoon Jang, Jeong Chul Lee, Won Mok Kim, Joon Sung Lee, Donghwan Kim

Research output: Contribution to journalArticle

45 Citations (Scopus)

Abstract

This study addresses the optimization of rf magnetron-sputtered hydrogenated ZnO:Al (HAZO) films as front contacts in microcrystalline silicon solar cells. The front contact of a solar cell has to be highly conductive and highly transparent to visible and infrared radiation. Furthermore, it has to scatter the incident light efficiently in order for the light to be effectively trapped in the underlying silicon layers. In this research, HAZO films were rf-magnetron-sputtered on glass substrates from a ceramic (98 wt% ZnO, 2 wt% Al 2O 3) target. Various compositions of AZO films on glass substrates were prepared by changing the H 2/(Ar + H 2) ratio of the sputtering gas. The resulting smooth films exhibited high transparencies (T ≥ 85% for visible light including all reflection losses) and excellent electrical properties (ρ = 2.7 × 10 -4 Ω · cm). Depending on their structural properties, these films developed different surface textures upon post-deposition etching using diluted hydrochloric acid. The light-scattering properties of these films could be controlled simply by varying the etching time. Moreover, the electrical properties of the films were not affected by the etching process. Therefore, within certain limits, it is possible to optimize the electro-optical and light-scattering properties separately. The microcrystalline silicon (μc-Si:H)-based p-i-n solar cells prepared using these new texture-etched AZO:H substrates showed high quantum efficiencies in the long wavelength range, thereby demonstrating effective light trapping. Using the optimum AZO:H thin-film textured surface, we achieved a p-i-n μc-Si solar cell efficiency of 7.78%.

Original languageEnglish
Pages (from-to)1318-1322
Number of pages5
JournalCurrent Applied Physics
Volume9
Issue number6
DOIs
Publication statusPublished - 2009 Nov 1

Keywords

  • μc-Si:H solar cells
  • Hydrogenated ZnO:Al
  • RF magnetron sputter
  • Surface texture

ASJC Scopus subject areas

  • Materials Science(all)
  • Physics and Astronomy(all)

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  • Cite this

    Tark, S. J., Kang, M. G., Park, S., Jang, J. H., Lee, J. C., Kim, W. M., Lee, J. S., & Kim, D. (2009). Development of surface-textured hydrogenated ZnO: Al thin-films for μc-Si solar cells. Current Applied Physics, 9(6), 1318-1322. https://doi.org/10.1016/j.cap.2008.12.015