Issue 25, 2020

First principles study of reactions in alucone growth: the role of the organic precursor

Abstract

Organic–inorganic hybrid materials are a unique class of materials with properties driven by the organic and inorganic components, making them useful for flexible devices. Molecular layer deposition (MLD) offers novel pathways for the fabrication of such hybrids by using inorganic metal precursors and the vast range of organic molecules with tunable properties. To investigate and understand the mechanism of growth a combination of theoretical and experimental data is needed. In this contribution, we present a first principles investigation of the molecular mechanism of the growth of hybrid organic–inorganic thin films of aluminium alkoxides, known as “alucones” grown by MLD. We explore the interactions between precursors by analyzing the MLD reaction products of the alumina surface terminated with Al(CH3) groups after the trimethyl aluminium pulse; this yields monomethyl-Al2O3 (Al-CH3-Al2O3) and dimethyl-Al2O3 (Al(CH3)2-Al2O3) terminated surfaces. The organic precursors are ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TEG) and tetraethylene glycol (FEG). A detailed comparison with alucones grown with ethylene glycol (EG) and glycerol (GL) precursors is presented to assist the interpretation of experimental findings regarding the differences in the hybrid films grown by EG and GL. The results show that Al–O formation with release of methane is favorable for all precursors. EG and GL can lie flat and create so-called double reactions through the reaction of the two terminal hydroxyl groups with the surface fragments. This phenomenon removes active hydroxyl sites for EG. However, for GL the third hydroxyl group is available and growth can proceed. This analysis shows the origin of differences in thickness of alucones found for EG and GL.

Graphical abstract: First principles study of reactions in alucone growth: the role of the organic precursor

Article information

Article type
Paper
Submitted
15 Apr. 2020
Accepted
12 Jūn. 2020
First published
18 Jūn. 2020

Dalton Trans., 2020,49, 8710-8721

First principles study of reactions in alucone growth: the role of the organic precursor

A. Muriqi and M. Nolan, Dalton Trans., 2020, 49, 8710 DOI: 10.1039/D0DT01376E

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