Comparative study of the interface passivation properties of LiF & Al2O3 using silicon MIS capacitor
(2024) Applied Physics Letters — Vol. 124, n° 14, p. 142901 (2024)
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- Authors
Scaffidi, Romain 
- Abstract
- Lithium fluoride (LiF) is currently a very popular dielectric material, used as passivation or transport layer in a variety of applications and especially in high-efficiency solar cells. Despite this, its conduction properties and interface behaviour with silicon remain largely unexplored. In this work, a LiF metal-insulator-semiconductor (MIS) structure is fabricated, characterized, and its properties are compared to the well-understood aluminium oxide (Al2O3) MIS structure. First, a higher current density in LiF compared to Al2O3 is highlighted, as well as its PN junction-like behaviour with n-type silicon (n-Si), being rather unconventional for a dielectric layer. CV measurements showcase the likely presence of an interface defect, causing an increase in the apparent doping and a shift in the flat-band voltage VF B by +70 meV. This defect is found to be of the acceptor type, which renders the interface fixed charge more negative and improve the field-effect passivation in case of a negative Qf . Finally, a density of interface states Dit ≈ 2 × 1011 cm−2eV−1 was found for LiF/n-Si, which is a low value showing appropriate chemical passivation at the interface. Overall, this work enables to shine more light on the interface properties of LiF on n-Si, which is an essential step towards its wider use in state-of-the art solar cells and other silicon-based devices.
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Citations
Parion, J., Scaffidi, R., Duerinckx, F., Sivaramakrishnan, H., Flandre, D., Poortmans, J., & Vermang, B. (2024). Comparative study of the interface passivation properties of LiF & Al2O3 using silicon MIS capacitor. Applied Physics Letters, 124(14), 142901. https://doi.org/10.10363/5.0203484 (Original work published 2024)