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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32 Citations (Scopus)


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
Issue number1
Publication statusPublished - 2017 Dec 1

Bibliographical note

Funding Information:
This work was supported by the Research and Development program of the Korea Institute of Energy Research (B7-2426). This work was also supported by the R&D Platform Development Project (Project No. 20163010012230) and the Energy Technology Development Program (Project No. 20178520000470) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea Government Ministry of Knowledge Economy.

Publisher Copyright:
© 2017 The Author(s).

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