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Effect of alkanethiol chain length on the oxidation resistance of self-assembled monolayer passivated Ge(100) surfaces
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Date
2023-06-08
Authors
Garvey, Shane
Maccioni, Barbara
Serino, Andrew C.
Holmes, Justin D.
Nolan, Michael
Draeger, Nerissa
Long, Brenda
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier B.V.
Published Version
Abstract
The use of self-assembled monolayers (SAMs) of heteroalkanes as passivation layers to protect against oxidation has been studied on a variety of materials. However, typically heteroalkanes with C8 and longer have been used, since the contributing van der Waals between the carbon chains is a significant stabilising force and the longer the chain the greater the force. The industry requirement for passivating semiconducting materials is that they remain oxide free for a queue time of 24 h. The remit of this study is to explore whether passivation using shorter chain alkanethiols, which would be beneficial for reducing carbon, will work to prevent re-oxidation over this time frame. A series of 1-alkanethiols, with chain lengths from C2 to C12 are used to create SAMs on Ge(100) and a study of the re-oxidation of the passivated Ge upon exposure to ambient conditions is undertaken in an effort to determine how chain length effects oxidation resistance of the passivated Ge. X-ray photoelectron spectroscopy is used, complimented by water contact angle measurements to show that the longer thiol molecules outperform their shorter-chain counterparts at inhibiting re-oxidation over 168 h of exposure to ambient. Nonetheless, Ge surfaces passivated by the short-chain thiols, down to C4, still display acceptable resistance to re-oxidation. Finally, a detailed summary of density functional theory simulations whereby the most stable SAM structures and coverages are explored.
Description
Keywords
Alkanethiols , Germanium , Oxidation resistance , Passivation , Self-assembled monolayers , Semiconductor
Citation
Garvey, S., Maccioni, B., Serino, A. C., Holmes, J. D., Nolan, M., Draeger, N. and Long, B. (2023) 'Effect of alkanethiol chain length on the oxidation resistance of self-assembled monolayer passivated Ge (100) surfaces', Thin Solid Films, 778, p.139875 (9pp). doi: 10.1016/j.tsf.2023.139875