Modeling Field Effect in Black Silicon and Its Impact on Device Performance

Black silicon (b-Si) has improved the performance of solar cells and photodetectors due to the excellent optics and surface passivation achieved with atomic layer deposition (ALD) dielectric films. One major reason for the success is the strong field effect caused by the high density of fixed charge...

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Bibliographic Details
Published in:IEEE transactions on electron devices 2020-04, Vol.67 (4), p.1-8
Main Authors: Heinonen, Juha, Pasanen, Toni P., Vahanissi, Ville, Juntunen, Mikko A., Savin, Hele
Format: Article
Language:English
Subjects:
Atomic layer deposition (ALD)
Atomic layer epitaxy
black silicon
Computer simulation
Current carriers
Dielectric strength
Electric charge
Electric fields
Electrical junctions
Electrical properties
field effect
Junctions
Nanostructures
Needles
Passivity
photodiode
Photodiodes
Photovoltaic cells
Silicon
Silicon devices
simulation
Solar cells
Spectral sensitivity
Surface morphology
Surface treatment
Thin films
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Summary:Black silicon (b-Si) has improved the performance of solar cells and photodetectors due to the excellent optics and surface passivation achieved with atomic layer deposition (ALD) dielectric films. One major reason for the success is the strong field effect caused by the high density of fixed charges present in the dielectric. Depending on the device, the field effect can be utilized also in a more active role than for mere surface passivation, including the formation of floating and/or induced junctions in silicon devices. However, in order to utilize the field effect efficiently, a deeper understanding of the thin-film charge-induced electric field and its effects on charge carriers in b-Si is required. Here, we investigate the field effect in b-Si using the Silvaco Atlas semiconductor device simulator. By studying the electric field and charge-carrier profiles, we develop a model where the electrical properties of b-Si can be approximated with a planar surface, which significantly simplifies the device-level simulations. We validate the model by simulating the spectral response of a b-Si-induced junction photodiode achieving less than 1% difference compared with experimental device performance in a wide range of wavelengths. Finally, we apply the model to study how variation in surface recombination velocity affects the short-wavelength sensitivity and dynamic range in a b-Si photodiode.
ISSN:0018-9383
1557-9646
DOI:10.1109/TED.2020.2975145