Effect of ozone concentration on silicon surface passivation by atomic layer deposited Al2O3

Guillaume von Gastrow (Corresponding Author), Shuo Li, Matti Putkonen, Mikko Laitinen, Timo Sajavaara, Hele Savin

    Research output: Contribution to journalArticleScientificpeer-review

    13 Citations (Scopus)

    Abstract

    We study the impact of ozone-based Al2O3 Atomic Layer Deposition (ALD) on the surface passivation quality of crystalline silicon. We show that the passivation quality strongly depends on the ozone concentration: the higher ozone concentration results in lower interface defect density and thereby improved passivation. In contrast to previous studies, our results reveal that too high interface hydrogen content can be detrimental to the passivation. The interface hydrogen concentration can be optimized by the ozone-based process; however, the use of pure ozone increases the harmful carbon concentration in the film. Here we demonstrate that low carbon and optimal hydrogen concentration can be achieved by a single process combining the water- and ozone-based reactions. This process results in an interface defect density of 2 * 1011 eV - 1 cm - 2, and maximum surface recombination velocities of 7.1 cm/s and 10 cm/s, after annealing and after an additional firing at 800 °C, respectively. In addition, our results suggest that the effective oxide charge density can be optimized in a simple way by varying the ozone concentration and by injecting water to the ozone process.
    Original languageEnglish
    Pages (from-to)2402-2407
    JournalApplied Surface Science
    Volume357, Part B
    DOIs
    Publication statusPublished - 2015
    MoE publication typeA1 Journal article-refereed

    Keywords

    • Atomic Layer Deposition
    • Al2O3
    • ozone
    • surface passivation
    • interface

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    von Gastrow, G., Li, S., Putkonen, M., Laitinen, M., Sajavaara, T., & Savin, H. (2015). Effect of ozone concentration on silicon surface passivation by atomic layer deposited Al2O3. Applied Surface Science, 357, Part B, 2402-2407. https://doi.org/10.1016/j.apsusc.2015.09.263