TY - JOUR

T1 - Comparing the Gettering Effect of Heavily Doped Polysilicon Films and Its Implications for Tunnel Oxide-Passivated Contact Solar Cells

AU - Yang, Zhongshu

AU - Krügener, Jan

AU - Feldmann, Frank

AU - Polzin, Jana Isabelle

AU - Steinhauser, Bernd

AU - Aleshin, Matvei

AU - Le, Tien T.

AU - Macdonald, Daniel

AU - Liu, An Yao

N1 - Funding Information: This work was supported by the Australian Renewable Energy Agency (ARENA) through project RND017 and the Australian Centre for Advanced Photovoltaics (ACAP). A.L. acknowledges funding from the ACAP postdoctoral fellowship scheme. This work was made possible through the access to the NCRIS facilities (Heavy Ion Accelerator Capability), the ACT node of the Australian National Fabrication Facility (ANFF‐ACT), and the Australian Microscopy & Microanalysis Research Facility at the Centre for Advanced Microscopy, at the Australian National University (ANU). The authors are grateful to the ANU colleagues Dr. Frank Brink and Dr. Thomas Ratcliff for assistance with scanning electron microscopy and ion implantation processes.

PY - 2023/4/28

Y1 - 2023/4/28

N2 - In addition to excellent surface passivation and carrier selectivity, the structure based on the heavily doped polysilicon layer on an ultrathin silicon oxide interlayer also demonstrates strong impurity gettering effects. Herein, the gettering strength of a range of phosphorus- or boron-doped polysilicon films from different fabrication techniques is assessed and compared. Iron, one of the most common metallic impurities in silicon, is used as a tracer impurity to quantify the gettering strength (segregation coefficient). A comparison of the experimental results to the literature, combined with measurements of the electrically active and inactive dopant concentrations, enables us to suggest the main gettering mechanisms in different polysilicon films. The differences in the segregation coefficients of the phosphorus-doped polysilicon films for iron are within one order of magnitude, in spite of their different combinations of gettering mechanisms. On the other hand, boron-doped polysilicon films show a large variation in their gettering effects, although the predominant gettering mechanisms are all attributed to electrically inactive boron, according to the current understanding of the gettering mechanisms from the literature. Finally, the impact of different polysilicon gettering effects on the efficiency of tunnel oxide-passivated contact (TOPCon) cells is simulated and discussed.

AB - In addition to excellent surface passivation and carrier selectivity, the structure based on the heavily doped polysilicon layer on an ultrathin silicon oxide interlayer also demonstrates strong impurity gettering effects. Herein, the gettering strength of a range of phosphorus- or boron-doped polysilicon films from different fabrication techniques is assessed and compared. Iron, one of the most common metallic impurities in silicon, is used as a tracer impurity to quantify the gettering strength (segregation coefficient). A comparison of the experimental results to the literature, combined with measurements of the electrically active and inactive dopant concentrations, enables us to suggest the main gettering mechanisms in different polysilicon films. The differences in the segregation coefficients of the phosphorus-doped polysilicon films for iron are within one order of magnitude, in spite of their different combinations of gettering mechanisms. On the other hand, boron-doped polysilicon films show a large variation in their gettering effects, although the predominant gettering mechanisms are all attributed to electrically inactive boron, according to the current understanding of the gettering mechanisms from the literature. Finally, the impact of different polysilicon gettering effects on the efficiency of tunnel oxide-passivated contact (TOPCon) cells is simulated and discussed.

KW - gettering

KW - iron

KW - polysilicon/oxide passivating contacts

KW - segregation coefficient

KW - silicon solar cells

UR - http://www.scopus.com/inward/record.url?scp=85135252208&partnerID=8YFLogxK

U2 - 10.1002/solr.202200578

DO - 10.1002/solr.202200578

M3 - Article

AN - SCOPUS:85135252208

VL - 7

JO - Solar RRL

JF - Solar RRL

IS - 8

M1 - 2200578

ER -