Effect of MACE Parameters on Electrical and Optical Properties of ALD Passivated Black Silicon
Loading...
Access rights
openAccess
acceptedVersion
URL
Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
This publication is imported from Aalto University research portal.
View publication in the Research portal (opens in new window)
View/Open full text file from the Research portal (opens in new window)
Other link related to publication (opens in new window)
View publication in the Research portal (opens in new window)
View/Open full text file from the Research portal (opens in new window)
Other link related to publication (opens in new window)
Date
2019-07-01
Major/Subject
Mcode
Degree programme
Language
en
Pages
6
Series
IEEE Journal of Photovoltaics, Volume 9, issue 4, pp. 974-979
Abstract
Metal-assisted chemical etching (MACE) enables efficient texturing of diamond-wire sawn multicrystalline silicon (mc-Si) wafers. However, the excellent optics are often sacrificed by polishing the surface to achieve better surface passivation with chemical-vapor-deposited (CVD) silicon nitride (SiNx). In this work, we show that a polishing step is not required when CVD SiNx is replaced with atomic-layer-deposited (ALD) aluminum oxide (Al2O3). Indeed, while polishing increases reflectance, it has in general only very modest effect on surface recombination velocity of ALD-passivated b-Si. Furthermore, since ALD Al2O3 is compatible with various surface morphologies due to its excellent conformality, the MACE parameters can be more freely adjusted. First, the concentration of silver nitrate (AgNO3) in AgNO3/H2O solution that is used to deposit Ag nanoparticles is shown to affect the final b-Si morphology. Instead of needle-shaped b-Si produced by 5 mmol/L AgNO3 concentration, two orders of magnitude lower AgNO3 concentration produces porous structures, which are more challenging to passivate. Additionally, we demonstrate that a separate Ag nanoparticle removal step in nitric acid (HNO3) is not a prerequisite for high carrier lifetime. Instead, Ag nanoparticles present during polishing in a HF/HNO3/H2O solution affect the final b-Si morphology by accelerating the etching of Si. The results demonstrate that no trade-offs are necessary between optical and electrical properties of MACE b-Si when using ALD.Description
Keywords
black silicon, nanostructure, metal assisted chemical etching, atomic layer deposition
Other note
Citation
Chen, K, Pasanen, T, Vähänissi, V & Savin, H 2019, ' Effect of MACE Parameters on Electrical and Optical Properties of ALD Passivated Black Silicon ', IEEE Journal of Photovoltaics, vol. 9, no. 4, 8728144, pp. 974-979 . https://doi.org/10.1109/JPHOTOV.2019.2917787