Wednesday, November 13, 2019

New Liquid phase Atomic Layer Deposition (ALD) — A Breakthrough in ALD

Chemical engineers at Ecole Polytechnique Federale de Lausanne, Switzerland, invented ALD in the liquid phase that can produce materials indistinguishable from those made in the gas phase, with far cheaper equipment and no excess precursors. The researchers achieved this breakthrough by carefully measuring the ratio of the reacting precursors before injecting them onto the surface of a substrate. This way, they used exactly the right amount of precursor, with no leftovers that can cause unwanted reactions or be wasted. 

The new method also reduces costs by requiring only standard lab equipment for chemical synthesis. It can also be easily scaled up to coat more than 150 g of material with the same cheap equipment, without loss of coating quality. The technique can even achieve coatings that are usually not possible using gas-phase ALD, e.g., by using volatile precursors with extremely low volatility.

More information:


A cheaper way to scale up atomic layer deposition, Phys.org (LINK)

Benjamin P. Le Monnier et al. Atomic Layer Deposition on Dispersed Materials in Liquid Phase by Stoichiometrically Limited Injections, Advanced Materials (2019). DOI: 10.1002/adma.201904276

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By Abhishekkumar Thakur

1 comment:

  1. Dear Jonas and Abhishekkumar,

    This work is interesting and certainly useful for certain cases, but I hardly see the breakthrough. The authors make statements without being aware of the existing literature, especially on ALD on high-surface-area powders. Here below a few points questioning their motivation:

    1) "ALD on high-surface-area powders makes use of excess precusors" FALSE! In ALD on high-surface-area powders, ~100% precursor utilization can be achieved. See: https://www.sciencedirect.com/science/article/pii/S0257897207005130 and https://www.sciencedirect.com/science/article/pii/S1385894715000960?via%3Dihub

    2) Their process cannot be called ALD due to its inherently not self-limiting nature. Any excess precursor will lead to excess growth in the next half-cycle, given the absence of purging steps.

    3) Real liquid-phase ALD has been already shown. https://pubs.acs.org/doi/10.1021/acs.nanolett.5b01424 When referring to it, the authors say that it involves huge precursor excesses (FALSE) and solvent excesses (like their process). So, no point.

    4) The authors make use of solvents that (i) need to be removed, and (ii) are generally not good with organic powders, which are either soluble or degradable.

    Overall, their approach could be useful when using non-volatile precursors (as also very well explained here https://pubs.acs.org/doi/10.1021/acs.nanolett.5b01424) and/or for processing highly cohesive inorganic powders which are difficult to mix/fluidize.

    So, most of their motivation doesn’t stand.

    Greetings,
    Damiano La Zara (TU Delft)

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