skip to main content

DOE PAGESDOE PAGES

This content will become publicly available on January 10, 2019

Title: Mechanism of Na accumulation at extended defects in Si from first-principles

Sodium (Na) impurities in silicon solar cells are considered to play an important role in potential-induced degradation (PID), a significant cause of solar cell degradation and failure. Shorting due to Na accumulation at extended defects has been suggested as a culprit for PID. However, it is not clear how the extended defects are decorated by Na impurities. Using first-principles density functional theory calculations, we find that Na impurities segregate from the bulk into extended defects such as intrinsic stacking faults and Sigma 3 (111) grain boundaries. The energy barrier required for Na to escape from the extended defects is substantial and similar to the sum of the barrier energy in bulk Si (1.1-1.2 eV) and the segregation energy to the stacking fault (~0.7 eV). Surprisingly, the migration barrier for Na diffusion within the extended defects is even higher than the energy barrier for escaping. Furthermore, the results suggest that the extended defects likely accumulate Na as the impurities segregate to the defects from the bulk, rather than because of migration through the extended defects. Published by AIP Publishing.
Authors:
 [1] ;  [1]
  1. Argonne National Lab. (ANL), Lemont, IL (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 123; Journal Issue: 16; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
Argonne National Laboratory, Center for Nanoscale Materials; Argonne National Laboratory, Laboratory Directed Research and Development (LDRD); USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1461433
Alternate Identifier(s):
OSTI ID: 1416457

Park, Ji -Sang, and Chan, Maria K. Y.. Mechanism of Na accumulation at extended defects in Si from first-principles. United States: N. p., Web. doi:10.1063/1.5003385.
Park, Ji -Sang, & Chan, Maria K. Y.. Mechanism of Na accumulation at extended defects in Si from first-principles. United States. doi:10.1063/1.5003385.
Park, Ji -Sang, and Chan, Maria K. Y.. 2018. "Mechanism of Na accumulation at extended defects in Si from first-principles". United States. doi:10.1063/1.5003385.
@article{osti_1461433,
title = {Mechanism of Na accumulation at extended defects in Si from first-principles},
author = {Park, Ji -Sang and Chan, Maria K. Y.},
abstractNote = {Sodium (Na) impurities in silicon solar cells are considered to play an important role in potential-induced degradation (PID), a significant cause of solar cell degradation and failure. Shorting due to Na accumulation at extended defects has been suggested as a culprit for PID. However, it is not clear how the extended defects are decorated by Na impurities. Using first-principles density functional theory calculations, we find that Na impurities segregate from the bulk into extended defects such as intrinsic stacking faults and Sigma 3 (111) grain boundaries. The energy barrier required for Na to escape from the extended defects is substantial and similar to the sum of the barrier energy in bulk Si (1.1-1.2 eV) and the segregation energy to the stacking fault (~0.7 eV). Surprisingly, the migration barrier for Na diffusion within the extended defects is even higher than the energy barrier for escaping. Furthermore, the results suggest that the extended defects likely accumulate Na as the impurities segregate to the defects from the bulk, rather than because of migration through the extended defects. Published by AIP Publishing.},
doi = {10.1063/1.5003385},
journal = {Journal of Applied Physics},
number = 16,
volume = 123,
place = {United States},
year = {2018},
month = {1}
}

Works referenced in this record:

Generalized Gradient Approximation Made Simple
journal, October 1996
  • Perdew, John P.; Burke, Kieron; Ernzerhof, Matthias
  • Physical Review Letters, Vol. 77, Issue 18, p. 3865-3868
  • DOI: 10.1103/PhysRevLett.77.3865

Projector augmented-wave method
journal, December 1994

Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set
journal, October 1996