Tantalum oxide/silicon nitride: A negatively charged surface passivation stack for silicon solar cells

Yimao Wan; James Bullock; Andres Cuevas

doi:10.1063/1.4921416

Tantalum oxide/silicon nitride: A negatively charged surface passivation stack for silicon solar cells

Yimao Wan, James Bullock, Andres Cuevas

Research output: Contribution to journal › Article › peer-review

26 Citations (Scopus)

Abstract

This letter reports effective passivation of crystalline silicon (c-Si) surfaces by thermal atomic layer deposited tantalum oxide (Ta₂O₅) underneath plasma enhanced chemical vapour deposited silicon nitride (SiN_x). Cross-sectional transmission electron microscopy imaging shows an approximately 2 nm thick interfacial layer between Ta₂O₅ and c-Si. Surface recombination velocities as low as 5.0 cm/s and 3.2 cm/s are attained on p-type 0.8 Ω·cm and n-type 1.0 Ω·cm c-Si wafers, respectively. Recombination current densities of 25 fA/cm² and 68 fA/cm² are measured on 150 Ω/sq boron-diffused p⁺ and 120 Ω/sq phosphorus-diffused n⁺ c-Si, respectively. Capacitance-voltage measurements reveal a negative fixed insulator charge density of -1.8 × 10¹²cm^-2 for the Ta₂O₅ film and -1.0 × 10¹²cm^-2 for the Ta₂O₅/SiN_x stack. The Ta₂O₅/SiN_x stack is demonstrated to be an excellent candidate for surface passivation of high efficiency silicon solar cells.

Original language	English
Article number	201601
Journal	Applied Physics Letters
Volume	106
Issue number	20
DOIs	https://doi.org/10.1063/1.4921416
Publication status	Published - 18 May 2015

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title = "Tantalum oxide/silicon nitride: A negatively charged surface passivation stack for silicon solar cells",

abstract = "This letter reports effective passivation of crystalline silicon (c-Si) surfaces by thermal atomic layer deposited tantalum oxide (Ta2O5) underneath plasma enhanced chemical vapour deposited silicon nitride (SiNx). Cross-sectional transmission electron microscopy imaging shows an approximately 2 nm thick interfacial layer between Ta2O5 and c-Si. Surface recombination velocities as low as 5.0 cm/s and 3.2 cm/s are attained on p-type 0.8 Ω·cm and n-type 1.0 Ω·cm c-Si wafers, respectively. Recombination current densities of 25 fA/cm2 and 68 fA/cm2 are measured on 150 Ω/sq boron-diffused p+ and 120 Ω/sq phosphorus-diffused n+ c-Si, respectively. Capacitance-voltage measurements reveal a negative fixed insulator charge density of -1.8 × 1012cm-2 for the Ta2O5 film and -1.0 × 1012cm-2 for the Ta2O5/SiNx stack. The Ta2O5/SiNx stack is demonstrated to be an excellent candidate for surface passivation of high efficiency silicon solar cells.",

author = "Yimao Wan and James Bullock and Andres Cuevas",

note = "Publisher Copyright: {\textcopyright} 2015 AIP Publishing LLC.",

year = "2015",

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doi = "10.1063/1.4921416",

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T1 - Tantalum oxide/silicon nitride

T2 - A negatively charged surface passivation stack for silicon solar cells

AU - Wan, Yimao

AU - Bullock, James

AU - Cuevas, Andres

PY - 2015/5/18

Y1 - 2015/5/18

N2 - This letter reports effective passivation of crystalline silicon (c-Si) surfaces by thermal atomic layer deposited tantalum oxide (Ta2O5) underneath plasma enhanced chemical vapour deposited silicon nitride (SiNx). Cross-sectional transmission electron microscopy imaging shows an approximately 2 nm thick interfacial layer between Ta2O5 and c-Si. Surface recombination velocities as low as 5.0 cm/s and 3.2 cm/s are attained on p-type 0.8 Ω·cm and n-type 1.0 Ω·cm c-Si wafers, respectively. Recombination current densities of 25 fA/cm2 and 68 fA/cm2 are measured on 150 Ω/sq boron-diffused p+ and 120 Ω/sq phosphorus-diffused n+ c-Si, respectively. Capacitance-voltage measurements reveal a negative fixed insulator charge density of -1.8 × 1012cm-2 for the Ta2O5 film and -1.0 × 1012cm-2 for the Ta2O5/SiNx stack. The Ta2O5/SiNx stack is demonstrated to be an excellent candidate for surface passivation of high efficiency silicon solar cells.

AB - This letter reports effective passivation of crystalline silicon (c-Si) surfaces by thermal atomic layer deposited tantalum oxide (Ta2O5) underneath plasma enhanced chemical vapour deposited silicon nitride (SiNx). Cross-sectional transmission electron microscopy imaging shows an approximately 2 nm thick interfacial layer between Ta2O5 and c-Si. Surface recombination velocities as low as 5.0 cm/s and 3.2 cm/s are attained on p-type 0.8 Ω·cm and n-type 1.0 Ω·cm c-Si wafers, respectively. Recombination current densities of 25 fA/cm2 and 68 fA/cm2 are measured on 150 Ω/sq boron-diffused p+ and 120 Ω/sq phosphorus-diffused n+ c-Si, respectively. Capacitance-voltage measurements reveal a negative fixed insulator charge density of -1.8 × 1012cm-2 for the Ta2O5 film and -1.0 × 1012cm-2 for the Ta2O5/SiNx stack. The Ta2O5/SiNx stack is demonstrated to be an excellent candidate for surface passivation of high efficiency silicon solar cells.

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U2 - 10.1063/1.4921416

DO - 10.1063/1.4921416

M3 - Article

SN - 0003-6951

VL - 106

JO - Applied Physics Letters

JF - Applied Physics Letters

IS - 20

M1 - 201601

ER -

Tantalum oxide/silicon nitride: A negatively charged surface passivation stack for silicon solar cells

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