The Early Steps of Molecule-to-Material Conversion in Chemical Vapor Deposition (CVD): A Case Study

03 March 2021, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Transition metal complexes with β-diketonate and diamine ligands are valuable precursors for the chemical vapor deposition (CVD) of metal oxide nanomaterials, but the metal-ligand bond cleavage mechanism on the growth surface is not clarified yet. We address this question by Density Functional Theory (DFT) and ab initio molecular dynamics (AIMD) in combination with the Bluemoon (BM) statistical sampling approach. AIMD simulations of the Zn β-diketonate-diamine complex Zn(hfa)2TMEDA (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA = N,N,N’,N’-tetramethylethylenediamine) show that rolling diffusion of this precursor at 500 K on a hydroxylated silica slab leads to an octahedral-to-square pyramidal rearrangement of its molecular geometry. The free energy profile of the octahedral-to-square pyramidal conversion indicates that the process barrier (5.8 kcal/mol) is of the order of the thermal energy at the operating temperature. The formation of hydrogen bonds with surface hydroxyls plays a key role in aiding the cleavage of a Zn-O bond. In the square-pyramidal complex, the Zn center has a free coordination position, which might promote the interaction with incoming reagents on the deposition surface. These results provide a valuable atomistic insight on the molecule-to-material conversion process which, in perspective, might help to tailor by design the first nucleation stages of the target ZnO-based nanostructures.

Keywords

Chemical Vapor Deposition
Density Functional Theory
Zinc Oxide Precursors
Transition Metal Complexes
Molecular Dynamics Simulations
Oxide Nanomaterials
Surface Chemistry
ab initio molecular dynamics

Supplementary materials

Title
Description
Actions
Title
331 Final.pov
Description
Actions

Comments

Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.