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Dopant Compensation within the Intrinsic Poly-Si Isolation Region in Poly-Si/SiOx Passivated IBC Si Solar Cells

Conference ·
DOI:https://doi.org/10.1063/5.0090546· OSTI ID:1889658
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We report on the effect of dopant compensation within intrinsic poly-Si regions between p- and n-type fingers of poly-Si/SiOx passivated interdigitated back contact (IBC) solar cells using intrinsic poly-Si as the isolation region between the doped poly-Si fingers. First, we show that dopants from the doped fingers contaminate the intrinsic gap, resulting in doping of the entire intrinsic gap and overlap of the dopant tails from each finger. Next, we show that despite this doping across the gap, shunting between the doped fingers does not occur. We show that this is a result of trap-assisted compensation creating a highly resistive intrinsic region, preventing shunt. We simulate shunt resistance across the gap based on local carrier concentration and deep trap density. We show that trap defects within the poly-Si enhance compensation between the dopant tails. We experimentally confirm these predictions by scanning spreading resistance microscopy of the gap showing ~20 um domain with resistivity ~10^7 ..omega.. cm. Additionally, Kelvin probe force microscopy are compared to finite element simulations which result in the same approximate shape for potential profile, indicating diode behavior across the isolation region. These results demonstrate the powerful effect that trap defects have within the poly-Si isolation region and suggest that precision patterning is not as essential as once thought.
Research Organization:
National Renewable Energy Laboratory (NREL), Golden, CO (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
DOE Contract Number:
AC36-08GO28308
OSTI ID:
1889658
Report Number(s):
NREL/CP-5900-79899; MainId:39117; UUID:9e2c36f7-f912-41e5-abb8-263ddaf03312; MainAdminID:24504
Country of Publication:
United States
Language:
English

References (5)

Exceeding conversion efficiency of 26% by heterojunction interdigitated back contact solar cell with thin film Si technology journal December 2017
Mobility and carrier concentration in polycrystalline silicon journal August 1984
Separating the two polarities of the POLO contacts of an 26.1%-efficient IBC solar cell journal January 2020
On the resistivity of polycrystalline silicon journal December 1983
Grain Boundaries Introduced deep Levels in Polysilicon journal October 1982

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Related Subjects

IBC
III-V
PV
SOLAR ENERGY
dopant compensation
interdigitated back contact
photovoltaic
poly Si/SiOx
shunt resistance