Hafnium oxide—A promising addition to the zoo of passivation layers for silicon solar cells?
Hafnium oxide (HfO2) has been known for a long time as a high-κ dielectric in silicon microelectronics. Recently, it has found its way into silicon photovoltaics, where it is applied as the surface-passivating dielectric. In this study, we examine the surface passivation quality of atomic-layer-depo...
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AIP Publishing LLC
2025-06-01
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| Online Access: | http://dx.doi.org/10.1063/5.0273888 |
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| author | Jan Schmidt Michael Winter Dag Luis Günther Floor Souren Jons Bolding Hindrik de Vries |
| author_facet | Jan Schmidt Michael Winter Dag Luis Günther Floor Souren Jons Bolding Hindrik de Vries |
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| description | Hafnium oxide (HfO2) has been known for a long time as a high-κ dielectric in silicon microelectronics. Recently, it has found its way into silicon photovoltaics, where it is applied as the surface-passivating dielectric. In this study, we examine the surface passivation quality of atomic-layer-deposited HfO2 layers on n-type silicon surfaces. We measure effective lifetimes of above 5 ms, corresponding to surface recombination velocities (SRVs) between 1 and 2 cm/s, which are among the lowest SRVs reported to date for HfO2-passivated silicon surfaces. We examine the passivation mechanism of the HfO2 by means of corona charging experiments, which reveal a significantly lower negative fixed charge density of HfO2 compared to Al2O3 and a lower interface state density. Hence, field-effect passivation is less pronounced and interface passivation is more pronounced for HfO2 compared to Al2O3. As an important consequence, for HfO2, no inversion layer formation occurs on n-type silicon surfaces in contrast to Al2O3, which makes HfO2 better suited than Al2O3 for edge passivation or rear passivation of “interdigitated back contact” cells on n-type silicon. The firing stability of the HfO2 passivation is found to improve by adding a hydrogen-rich silicon nitride (SiNx) capping layer. For HfO2/SiNx stacks with only 3 nm of HfO2, implied one-sun open-circuit voltages of 740 mV are attained after high-temperature firing in a conveyor-belt furnace, as used for the metal contact formation in industrial silicon solar cells. |
| format | Article |
| id | doaj-art-bf538cc2d10e4a8a92972d86161316d7 |
| institution | Kabale University |
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| publishDate | 2025-06-01 |
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| spelling | doaj-art-bf538cc2d10e4a8a92972d86161316d72025-08-20T03:28:52ZengAIP Publishing LLCAIP Advances2158-32262025-06-01156065001065001-710.1063/5.0273888Hafnium oxide—A promising addition to the zoo of passivation layers for silicon solar cells?Jan Schmidt0Michael Winter1Dag Luis Günther2Floor Souren3Jons Bolding4Hindrik de Vries5Institute for Solar Energy Research Hamelin (ISFH), Am Ohrberg 1, 31860 Emmerthal, GermanyInstitute for Solar Energy Research Hamelin (ISFH), Am Ohrberg 1, 31860 Emmerthal, GermanyInstitute for Solar Energy Research Hamelin (ISFH), Am Ohrberg 1, 31860 Emmerthal, GermanySALD B.V., Hastelweg 257, 5652CV Eindhoven, The NetherlandsSALD B.V., Hastelweg 257, 5652CV Eindhoven, The NetherlandsSALD B.V., Hastelweg 257, 5652CV Eindhoven, The NetherlandsHafnium oxide (HfO2) has been known for a long time as a high-κ dielectric in silicon microelectronics. Recently, it has found its way into silicon photovoltaics, where it is applied as the surface-passivating dielectric. In this study, we examine the surface passivation quality of atomic-layer-deposited HfO2 layers on n-type silicon surfaces. We measure effective lifetimes of above 5 ms, corresponding to surface recombination velocities (SRVs) between 1 and 2 cm/s, which are among the lowest SRVs reported to date for HfO2-passivated silicon surfaces. We examine the passivation mechanism of the HfO2 by means of corona charging experiments, which reveal a significantly lower negative fixed charge density of HfO2 compared to Al2O3 and a lower interface state density. Hence, field-effect passivation is less pronounced and interface passivation is more pronounced for HfO2 compared to Al2O3. As an important consequence, for HfO2, no inversion layer formation occurs on n-type silicon surfaces in contrast to Al2O3, which makes HfO2 better suited than Al2O3 for edge passivation or rear passivation of “interdigitated back contact” cells on n-type silicon. The firing stability of the HfO2 passivation is found to improve by adding a hydrogen-rich silicon nitride (SiNx) capping layer. For HfO2/SiNx stacks with only 3 nm of HfO2, implied one-sun open-circuit voltages of 740 mV are attained after high-temperature firing in a conveyor-belt furnace, as used for the metal contact formation in industrial silicon solar cells.http://dx.doi.org/10.1063/5.0273888 |
| spellingShingle | Jan Schmidt Michael Winter Dag Luis Günther Floor Souren Jons Bolding Hindrik de Vries Hafnium oxide—A promising addition to the zoo of passivation layers for silicon solar cells? AIP Advances |
| title | Hafnium oxide—A promising addition to the zoo of passivation layers for silicon solar cells? |
| title_full | Hafnium oxide—A promising addition to the zoo of passivation layers for silicon solar cells? |
| title_fullStr | Hafnium oxide—A promising addition to the zoo of passivation layers for silicon solar cells? |
| title_full_unstemmed | Hafnium oxide—A promising addition to the zoo of passivation layers for silicon solar cells? |
| title_short | Hafnium oxide—A promising addition to the zoo of passivation layers for silicon solar cells? |
| title_sort | hafnium oxide a promising addition to the zoo of passivation layers for silicon solar cells |
| url | http://dx.doi.org/10.1063/5.0273888 |
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