Dielectric Backside Passivation – Improvements by Dipole Optimization

Mikolajick, Thomas; Endler, I.; Rose, Marcus; Dirnstorfer, I.; Kupke, S.; Erben, Elke; Jakschik, S.

doi:10.4229/26theupvsec2011-2cv.4.41

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“…Charges are not formed independently of the silicon substrate. This finding was in contradiction to other studies, which reported Si–O–Al dipoles forming between Al 2 O 3 and interfacial SiO x on the silicon substrate. − However, the absence of dipoles was in accordance with the conclusion drawn from the slant-etched series, where the thickness dependency of V fb was attributed to charges at the interface and not to dipoles between the two oxides. Because the fixed charge formation is linked to the silicon substrate, it is not possible to create highly charged layers with multiple HfO 2 –SiO 2 –Al 2 O 3 sequences.…”

Section: Resultsmentioning

confidence: 99%

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On the Control of the Fixed Charge Densities in Al₂O₃-Based Silicon Surface Passivation Schemes

Simon

Jordan

Mikolajick

et al. 2015

ACS Appl. Mater. Interfaces

116

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A controlled field-effect passivation by a well-defined density of fixed charges is crucial for modern solar cell surface passivation schemes. Al2O3 nanolayers grown by atomic layer deposition contain negative fixed charges. Electrical measurements on slant-etched layers reveal that these charges are located within a 1 nm distance to the interface with the Si substrate. When inserting additional interface layers, the fixed charge density can be continuously adjusted from 3.5 × 10(12) cm(-2) (negative polarity) to 0.0 and up to 4.0 × 10(12) cm(-2) (positive polarity). A HfO2 interface layer of one or more monolayers reduces the negative fixed charges in Al2O3 to zero. The role of HfO2 is described as an inert spacer controlling the distance between Al2O3 and the Si substrate. It is suggested that this spacer alters the nonstoichiometric initial Al2O3 growth regime, which is responsible for the charge formation. On the basis of this charge-free HfO2/Al2O3 stack, negative or positive fixed charges can be formed by introducing additional thin Al2O3 or SiO2 layers between the Si substrate and this HfO2/Al2O3 capping layer. All stacks provide very good passivation of the silicon surface. The measured effective carrier lifetimes are between 1 and 30 ms. This charge control in Al2O3 nanolayers allows the construction of zero-fixed-charge passivation layers as well as layers with tailored fixed charge densities for future solar cell concepts and other field-effect based devices.

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Section: Resultsmentioning

confidence: 99%

“…Other groups identified dipoles at the SiO 2 /Al 2 O 3 interface. , Interface dipoles also shift V fb and provide field-effect passivation for the silicon surface . According to Kita et al, dipoles are formed at the interface of SiO x and high- k dielectrics because of an oxygen displacement due to different oxygen areal densities …”

Section: Introductionmentioning

confidence: 99%

On the Control of the Fixed Charge Densities in Al₂O₃-Based Silicon Surface Passivation Schemes

Simon

Jordan

Mikolajick

et al. 2015

ACS Appl. Mater. Interfaces

116

View full text Add to dashboard Cite

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Dielectric Backside Passivation – Improvements by Dipole Optimization

Cited by 1 publication

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On the Control of the Fixed Charge Densities in Al₂O₃-Based Silicon Surface Passivation Schemes

On the Control of the Fixed Charge Densities in Al₂O₃-Based Silicon Surface Passivation Schemes

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Dielectric Backside Passivation – Improvements by Dipole Optimization

Cited by 1 publication

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On the Control of the Fixed Charge Densities in Al2O3-Based Silicon Surface Passivation Schemes

On the Control of the Fixed Charge Densities in Al2O3-Based Silicon Surface Passivation Schemes

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On the Control of the Fixed Charge Densities in Al₂O₃-Based Silicon Surface Passivation Schemes

On the Control of the Fixed Charge Densities in Al₂O₃-Based Silicon Surface Passivation Schemes