ALD/MLD of novel layer-engineered Zn-based inorganic-organic hybrid thin films using heterobifunctional 4-aminophenol as an organic precursor

Modelling the growth reaction pathways of zincone ALD/MLD hybrid thin films: a DFT study

ALD/MLD hybrid thin films can be fabricated by combining atomic layer deposition (ALD) and molecular layer deposition (MLD). Even though this deposition method has been extensively used experimentally, the computational work required to acquire the reaction paths during the thin film deposition process is still in dire demand. We investigated hybrid thin films consisting of diethyl zinc and either 4-aminophenol or hydroquinone using both gas-phase and surface reactions to gain extensive knowledge of the complex phenomena occurring during the process of hybrid thin film deposition. We used density functional theory (DFT) to obtain the activation energies of these kinetic-dependent deposition processes. Different processes of ethyl ligand removal as ethane were discovered, and we found that the hydroxyl group of 4-aminophenol was more reactive than the amino group in the migration of hydrogen to an ethyl ligand within a complicated branching reaction chain.

Conformal Zn-Benzene Dithiol Thin Films for Temperature-Sensitive Electronics Grown via Industry-Feasible Atomic/Molecular Layer Deposition Technique

The atomic/molecular layer deposition (ALD/MLD) technique combining both inorganic and organic precursors is strongly emerging as a unique tool to design exciting new functional metal-organic thin-film materials. Here, this method is demonstrated to work even at low deposition temperatures and can produce highly stable and conformal thin films, fulfilling the indispensable prerequisites of today's 3D microelectronics and other potential industrial applications. This new ALD/MLD process is developed for Zn-organic thin films grown from non-pyrophoric bis-3-(N,N-dimethylamino)propyl zinc [Zn(DMP)2] and 1,4-benzene dithiol (BDT) precursors. This process yields air-stable Zn-BDT films with appreciably high growth per cycle (GPC) of 4.5 Å at 60 °C. The Zn/S ratio is determined at 0.5 with Rutherford backscattering spectrometry (RBS), in line with the anticipated (Zn─S─C6H6─S─)n bonding scheme. The high degree of conformality is shown using lateral high-aspect-ratio (LHAR) test substrates; scanning electron microscopy (SEM) analysis shows that the film penetration depth (PD) into the LHAR structure with cavity height of 500 nm is over 200 µm (i.e., aspect-ratio of 400). It is anticipated that the electrically insulating metal-organic Zn-BDT thin films grown via the solvent-free ALD/MLD technique, can be excellent barrier layers for temperature-sensitive and flexible electronic devices.

Low-temperature ALD/MLD growth of alucone and zincone thin films from non-pyrophoric precursors

The combined atomic/molecular layer deposition (ALD/MLD) technique is emerging as a state-of-the-art synthesis route for new metal-organic thin-film materials with a multitude of properties by combining those of the inorganic...

Nanoparticles functionalized ceramic membranes: fabrication, surface modification, and performance

Membrane technologies are used intensively for desalination and wastewater treatment. Water filtration using ceramic membranes exhibited high performance compared with polymeric membranes due to various properties such as high resistance to fouling, permeability, rejection rate, and chemical stability. Recently, the performance of nanocomposite ceramic membranes was improved due to the development in nanotechnology. This article focusses on the development of porous ceramic membranes and nanomaterial functionalized ceramic membranes for water filtration applications. At the beginning, various fabrication methods of ceramic membranes were described, and the effect of surface modification techniques on the membrane intrinsic properties was reviewed. Then, the performance of nanoparticles functionalized ceramic membranes was evaluated in terms of physicochemical properties, rejection rate, and water permeability. This work can help new entrants and established researchers to become familiar with the current challenges and developments of nanoparticle-incorporated ceramic membranes for water filtration applications.

Selective coordination with heterogeneous metal atoms for inorganic–organic hybrid layers

The synthesis of organic–inorganic hybrid materials using individual metal–organic molecules as building blocks has been of interest for the last few decades. These hybrid materials are appealing due to the opportunities they provide with respect to a variety of potential applications. Here, we report a novel metal–organic nanostructure made by a hybrid synthetic process that is comprised of thermal evaporation (TE) and atomic layer deposition (ALD) for the metalation of an organic layer. In this work, 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphyrin (p-(H₆)THPP) and tin(ii) bis(trimethylsilyl)amide (Sn(btsa)₂) (or diethylzinc (DEZ)) were utilized as the main organic layer and ALD precursors, respectively. Sn and Zn atoms were coordinated sequentially via surface chemical reactions on specific functional groups of the p-(H₆)THPP layer, which was deposited on a solid substrate. X-ray photoelectron spectroscopy (XPS) and UV-vis absorption spectroscopy were used to characterize and confirm the growth mechanism and optical properties of the synthesized hybrid films. This method should serve as a major breakthrough for building advanced organic–inorganic materials-based devices.

The fabrication of a metal–organic nanostructure was demonstrated by the hybrid synthesis process. The metal atoms such as Sn and Zn were sequentially coordinated on specific functional groups of the main organic layer by vapor phase metalation.

Reversible Photoswitching Function in Atomic/Molecular-Layer-Deposited ZnO:Azobenzene Superlattice Thin Films

We report new types of reversibly photoresponsive ZnO:azobenzene superlattice thin films fabricated through atomic/molecular-layer deposition (ALD/MLD) from diethylzinc, water, and 4,4'-azobenzene dicarboxylic acid precursors. In these ultrathin films, crystalline ZnO layers are interspersed with monomolecular photoactive azobenzene dicarboxylate layers. The thickness of the individual ZnO layers is precisely controlled by the number (m) of ALD cycles applied between two subsequent MLD cycles for the azobenzene layers; in our {[(Zn-O) _m +(Zn-O₂-C-C₆H₄-N=N-C₆H₄-C-O₂)] _n +(Zn-O) _m } samples, m ranges from 0 to 240. The photoresponsive behavior of the films is demonstrated with ultraviolet-visible spectroscopy; all the films are found to be photoreactive upon 360 nm irradiation, the kinetics of the resultant trans-cis photoisomerization somewhat depending on the superlattice structure. The reversibility of the photoisomerization reaction is then confirmed with a subsequent thermal treatment. Our work thus provides proof-of-concept evidence of the suitability of the ALD/MLD technology for the implementation of photoactive moieties such as azobenzene within an inorganic matrix as an attractive new methodology for creating novel light-switchable functional materials.

Atomic/molecular layer deposition of Cu–organic thin films

The gas-phase atomic/molecular layer deposition (ALD/MLD) technique is strongly emerging as a viable approach for fabricating new exciting inorganic–organic hybrid thin-film materials. Here we report new ALD/MLD processes for copper-based hybrid materials based on five different organic precursors.

Substantially enhanced Raman signal for inorganic–organic nanocomposites by ALD-TiO2 capping

Atomic layer deposition (ALD) enables conformal coating of various surface architectures with high-quality ultrathin films.

Growth characteristics of Ti-based fumaric acid hybrid thin films by molecular layer deposition

Ti-based fumaric acid hybrid thin films were successfully prepared using inorganic TiCl₄ and organic fumaric acid as precursors by molecular layer deposition (MLD).

Stability of molecular layer deposited zincone films: experimental and theoretical exploration

Experimental and theoretical degradation study of MLD grown hybrid inorganic–organic zincone films.

Iron-based inorganic–organic hybrid and superlattice thin films by ALD/MLD

Here we present novel layer-by-layer deposition processes for the fabrication of inorganic–organic hybrid thin films of the (–Fe–O–C₆H₄–O–)_n type and also superlattices where N thicker iron oxide layer blocks alternate with monomolecular-thin organic layers.

Guidance of growth mode and structural character in organic–inorganic hybrid materials – a comparative study

We investigated the influence of the functionality of organic ligands on film properties in organic–inorganic hybrid thin films deposited by atomic layer deposition.

Organic and inorganic-organic thin film structures by molecular layer deposition: A review

The possibility to deposit purely organic and hybrid inorganic-organic materials in a way parallel to the state-of-the-art gas-phase deposition method of inorganic thin films, i.e., atomic layer deposition (ALD), is currently experiencing a strongly growing interest. Like ALD in case of the inorganics, the emerging molecular layer deposition (MLD) technique for organic constituents can be employed to fabricate high-quality thin films and coatings with thickness and composition control on the molecular scale, even on complex three-dimensional structures. Moreover, by combining the two techniques, ALD and MLD, fundamentally new types of inorganic-organic hybrid materials can be produced. In this review article, we first describe the basic concepts regarding the MLD and ALD/MLD processes, followed by a comprehensive review of the various precursors and precursor pairs so far employed in these processes. Finally, we discuss the first proof-of-concept experiments in which the newly developed MLD and ALD/MLD processes are exploited to fabricate novel multilayer and nanostructure architectures by combining different inorganic, organic and hybrid material layers into on-demand designed mixtures, superlattices and nanolaminates, and employing new innovative nanotemplates or post-deposition treatments to, e.g., selectively decompose parts of the structure. Such layer-engineered and/or nanostructured hybrid materials with exciting combinations of functional properties hold great promise for high-end technological applications.

Mixing ALD/MLD-grown ZnO and Zn-4-aminophenol layers into various thin-film structures

Building 2D inorganic-organic hybrids by combining inorganic and organic constituents with molecular-layer precision is an attractive approach to fabricate novel materials with a tailored combination of properties from both entities. Here we demonstrate the potential of the combined atomic and molecular layer deposition (ALD/MLD) technique for the state-of-the-art synthesis of such materials and to fabricate both homogeneous thin-film mixtures and nanolaminates of ZnO and the Zn-4-aminophenol inorganic-organic hybrid. The thin films are deposited by varying the number of precursor cycles during the depositions. Diethyl zinc and 4-aminophenol (AP) are used as precursors for the Zn-AP hybrid depositions, and diethyl zinc and water for the ZnO depositions. The characterization of the mixed Zn-AP and ZnO films reveals that crystallinity, density, surface roughness, chemical stability, hardness and contact modulus are sensitively altered by even a minor insertion of Zn-AP hybrid into the ZnO structure. Fabrication of Zn-AP + ZnO nanolaminates with different thicknesses of the Zn-AP and ZnO layers provides us with an even better way to control the hardness and contact modulus, and also to enhance the chemical stability of the films.