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Analysis of the negative charges injected into a SiO 2 /SiN x stack using plasma charging technology for field‐effect passivation on a boron‐doped silicon surface
Author(s) -
Min Kwan Hong,
Hwang JeongMo,
Cho Eunwan,
Song Heeeun,
Park Sungeun,
Rohatgi Ajeet,
Kim Donghwan,
Lee HaeSeok,
Kang Yoonmook,
Ok YoungWoo,
Kang Min Gu
Publication year - 2021
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.3340
Subject(s) - passivation , analytical chemistry (journal) , common emitter , materials science , plasma enhanced chemical vapor deposition , boron , saturation current , doping , charge density , plasma , silicon , chemical vapor deposition , wafer , chemistry , layer (electronics) , optoelectronics , electrical engineering , nanotechnology , voltage , physics , organic chemistry , engineering , chromatography , quantum mechanics
We investigated field‐effect passivation by injecting negative charges into SiO 2 /SiN x stack using a plasma charge injection technique. The Si/SiO 2 /SiN x samples exhibited a very high flat‐band shift with a high injected negative charge density (>3.0 × 10 13 cm 2 ) after plasma negative charge injection; this density was higher than that for the well‐known Al 2 O 3 layer. Most injected negative charges were present within approximately 90 nm of the surface of the SiN x layer deposited by plasma‐enhanced chemical vapor deposition (PECVD) when comparing the capacitance–voltage analysis results obtained while etching the SiN x film considering four assumptions of the injected negative charge distribution. The saturation current density in a 90‐ohm/sq boron emitter decreased from ~90 to 50 fA/cm 2 after negative charge injection, which is equivalent to the J 0e of the structure passivated with an Al 2 O 3 /SiN x stack. Six‐inch n ‐type bifacial cells with an approximately 100‐ohm/sq boron emitter passivated with SiO 2 /SiN x displayed an approximately 0.2% increase in absolute cell efficiency after negative charge injection. In addition, n ‐PERT bifacial cells with a high boron sheet resistance of ~150 ohm/sq exhibited a 1.0% or higher absolute efficiency enhancement from a relatively low precharging efficiency of approximately 19.0%. We also demonstrated that the final efficiency after charging was comparable with n ‐PERT bifacial cells with Al 2 O 3 passivation, suggesting that the proposed process is a potential low‐cost alternative method that could replace expensive Al 2 O 3 processes.