Structural evolution of tunneling oxide passivating contact upon thermal annealing

Sungjin Choi, Kwan Hong Min, Myeong Sang Jeong, Jeong In Lee, Min Gu Kang, Hee Eun Song, Yoonmook Kang, Hae Seok Lee, Donghwan Kim, Ka Hyun Kim

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15 Citations (Scopus)

Abstract

We report on the structural evolution of tunneling oxide passivating contact (TOPCon) for high efficient solar cells upon thermal annealing. The evolution of doped hydrogenated amorphous silicon (a-Si:H) into polycrystalline-silicon (poly-Si) by thermal annealing was accompanied with significant structural changes. Annealing at 600 °C for one minute introduced an increase in the implied open circuit voltage (Voc) due to the hydrogen motion, but the implied Voc decreased again at 600 °C for five minutes. At annealing temperature above 800 °C, a-Si:H crystallized and formed poly-Si and thickness of tunneling oxide slightly decreased. The thickness of the interface tunneling oxide gradually decreased and the pinholes are formed through the tunneling oxide at a higher annealing temperature up to 1000 °C, which introduced the deteriorated carrier selectivity of the TOPCon structure. Our results indicate a correlation between the structural evolution of the TOPCon passivating contact and its passivation property at different stages of structural transition from the a-Si:H to the poly-Si as well as changes in the thickness profile of the tunneling oxide upon thermal annealing. Our result suggests that there is an optimum thickness of the tunneling oxide for passivating electron contact, in a range between 1.2 to 1.5 nm.

Original languageEnglish
Article number12853
JournalScientific reports
Volume7
Issue number1
DOIs
Publication statusPublished - 2017 Dec 1

ASJC Scopus subject areas

  • General

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    Choi, S., Min, K. H., Jeong, M. S., Lee, J. I., Kang, M. G., Song, H. E., Kang, Y., Lee, H. S., Kim, D., & Kim, K. H. (2017). Structural evolution of tunneling oxide passivating contact upon thermal annealing. Scientific reports, 7(1), [12853]. https://doi.org/10.1038/s41598-017-13180-y