Atomic Layer Deposition on Dispersed Materials in Liquid Phase by Stoichiometrically Limited Injections

• Published in: Advanced materials (Weinheim) 2019-12, Vol.31 (52), p.e1904276-n/a
• Main Authors: Le Monnier, Benjamin P., Wells, Frederick, Talebkeikhah, Farzaneh, Luterbacher, Jeremy S.
• Format: Article
• Language: English
• Subjects: Aluminum oxide; atomic layer deposition; Atomic layer epitaxy; Fluidized beds; Glassware; Industrial development; Laboratories; Liquid phases; Materials science; nanomaterials; nanostructured catalysts; Phosphates; Phosphoric acid; Precursors; Purging; Stoichiometry; surface chemistry; Thin films
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201904276

Atomic layer deposition (ALD) is a well‐established vapor‐phase technique for depositing thin films with high conformality and atomically precise control over thickness. Its industrial development has been largely confined to wafers and low‐surface‐area materials because deposition on high‐surface‐area materials and powders remains extremely challenging. Challenges with such materials include long deposition times, extensive purging cycles, and requirements for large excesses of precursors and expensive low‐pressure equipment. Here, a simple solution‐phase deposition process based on subsequent injections of stoichiometric quantities of precursor is performed using common laboratory synthesis equipment. Precisely measured precursor stoichiometries avoid any unwanted reactions in solution and ensure layer‐by‐layer growth with the same precision as gas‐phase ALD, without any excess precursor or purging required. Identical coating qualities are achieved when comparing this technique to Al2O3 deposition by fluidized‐bed reactor ALD (FBR‐ALD). The process is easily scaled up to coat >150 g of material using the same inexpensive laboratory glassware without any loss in coating quality. This technique is extended to sulfides and phosphates and can achieve coatings that are not possible using classic gas‐phase ALD, including the deposition of phosphates with inexpensive but nonvolatile phosphoric acid. Liquid‐phase atomic layer deposition is performed on high‐surface‐area dispersed nanomaterials at room temperature and pressure. This new method requires typical laboratory equipment, uses no excess precursors or purging steps, and allows for easy monitoring of the reaction by quantifying ligand release.