Microstructural evolution of ZrO2–HfO2 nanolaminate structures grown by atomic layer deposition

Zirconia–hafnia (ZrO2–HfO2) nanolaminate structures were grown using the atomic layer deposition (ALD) technique with different stacking sequences and layer thickness layer thicknesses. The microstructural evolution and surface roughness were compared with those of single-layer ZrO2 or HfO2 films using transmission electron microscopy and atomic force microscopy. Thin single-layer ALD-ZrO2 films were polycrystalline and composed of the tetragonal ZrO2 phase as-deposited, whereas thicker (>14 nm) films were composed mainly of the monoclinic phase. HfO2 films were amorphous as-deposited and crystallized into primarily monoclinic during subsequent anneals at temperatures over 500 °C. All the nanolaminate structures having individual layer thicknesses greater than approximately 2 nm were crystalline (mixture of tetragonal and monoclinic phases) independent of layer sequence and also exhibited a layer-to-layer epitaxy relationship within each grain. However, the identity of the starting layer determined the final grain size and surface roughness of the nanolaminates. A qualitative model for the observed microstructure evolution of the laminate films is proposed.

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Plasma Enhanced Atomic Layer Deposition of Ruthenium Films Using Ru(EtCp)2 Precursor

Coatings ◽

10.3390/coatings11020117 ◽

2021 ◽

Vol 11 (2) ◽

pp. 117

Author(s):

Alexander Rogozhin ◽

Andrey Miakonkikh ◽

Elizaveta Smirnova ◽

Andrey Lomov ◽

Sergey Simakin ◽

...

Keyword(s):

Surface Roughness ◽

Atomic Layer Deposition ◽

Substrate Temperature ◽

Secondary Ion Mass Spectrometry ◽

Film Growth ◽

Atomic Layer ◽

Grazing Incidence ◽

Force Microscopy ◽

Si Substrates ◽

Layer Deposition

Ruthenium thin films were deposited by plasma-enhanced atomic layer deposition (PEALD) technology using Ru(EtCp)2 and oxygen plasma on the modified surface of silicon and SiO2/Si substrates. The crystal structure, chemical composition, and morphology of films were characterized by grazing incidence XRD (GXRD), secondary ion mass spectrometry (SIMS), and atomic force microscopy (AFM) techniques, respectively. It was found that the mechanism of film growth depends crucially on the substrate temperature. The GXRD and SIMS analysis show that at substrate temperature T = 375 °C, an abrupt change in surface reaction mechanisms occurs, leading to the changing in film composition from RuO2 at low temperatures to pure Ru film at higher temperatures. It was confirmed by electrical resistivity measurements for Ru-based films. Mechanical stress in the films was also analyzed, and it was suggested that this factor increases the surface roughness of growing Ru films. The lowest surface roughness ~1.5 nm was achieved with a film thickness of 29 nm using SiO2/Si-substrate for deposition at 375 °C. The measured resistivity of Ru film is 18–19 µOhm·cm (as deposited).

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Direct Epitaxial Nanometer-Thin InN of High Structural Quality on 4H-SiC by Atomic Layer Deposition

10.26434/chemrxiv.12357284.v2 ◽

2020 ◽

Author(s):

Chih-Wei Hsu ◽

Petro Deminskyi ◽

Ivan Martinovic ◽

Ivan G. Ivanov ◽

Justinas Palisaitis ◽

...

Keyword(s):

Atomic Layer Deposition ◽

Indium Nitride ◽

Atomic Layer ◽

Structural Quality ◽

High Electron ◽

X Ray Diffraction ◽

High Quality ◽

Subsequent Formation ◽

Transmission Electron ◽

Layer Deposition

<div>Indium nitride (InN) is a highly promising material for high frequency electronics given its</div><div>low band gap and high electron mobility. The development of InN-based devices is hampered</div><div>by the limitations in depositing very thin InN films of high quality. We demonstrate growth of</div><div>high-structural-quality nanometer thin InN films on 4H-SiC by atomic layer deposition (ALD).</div><div>High resolution X-ray diffraction and transmission electron microscopy show epitaxial growth</div><div>and an atomically sharp interface between InN and 4H-SiC. The InN film is fully relaxed already after a few atomic layers and shows a very smooth morphology where the low surface</div><div>roughness (0.14 nm) is found to reproduced sub-nanometer surface features of the substrate. Raman measurements show an asymmetric broadening caused by grains in the InN film. Our results show the potential of ALD to prepare high quality nanometer-thin InN films for subsequent formation of heterojunctions.</div>

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Comparison of the Growth and Thermal Properties of Nonwoven Polymers after Atomic Layer Deposition and Vapor Phase Infiltration

Coatings ◽

10.3390/coatings11091028 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1028

Author(s):

Laura Keskiväli ◽

Pirjo Heikkilä ◽

Eija Kenttä ◽

Tommi Virtanen ◽

Hille Rautkoski ◽

...

Keyword(s):

Thermal Properties ◽

Electron Microscope ◽

Atomic Layer Deposition ◽

Atomic Layer ◽

Scanning Transmission Electron Microscope ◽

Scanning Calorimetry ◽

Polymeric Surfaces ◽

Transmission Electron ◽

Layer Deposition ◽

Scanning Transmission

The growth mechanism of Atomic Layer Deposition (ALD) on polymeric surfaces differs from growth on inorganic solid substrates, such as silicon wafer or glass. In this paper, we report the growth experiments of Al2O3 and ZnO on nonwoven poly-L-lactic acid (PLLA), polyethersulphone (PES) and cellulose acetate (CA) fibres. Material growth in both ALD and infiltration mode was studied. The structures were examined with a scanning electron microscope (SEM), scanning transmission electron microscope (STEM), attenuated total reflectance-fourier-transform infrared spectroscopy (ATR-FTIR) and 27Al nuclear magnetic resonance (NMR). Furthermore, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis were used to explore the effect of ALD deposition on the thermal properties of the CA polymer. According to the SEM, STEM and ATR-FTIR analysis, the growth of Al2O3 was more uniform than ZnO on each of the polymers studied. In addition, according to ATR-FTIR spectroscopy, the infiltration resulted in interactions between the polymers and the ALD precursors. Thermal analysis (TGA/DSC) revealed a slower depolymerization process and better thermal resistance upon heating both in ALD-coated and infiltrated fibres, more pronounced on the latter type of structures, as seen from smaller endothermic peaks on TA.

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Post-Annealing Effects on the Surface Roughness of Undoped and Al-Doped ZnO Thin Films Deposited by Atomic Layer Deposition

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.734-737.2492 ◽

2013 ◽

Vol 734-737 ◽

pp. 2492-2495

Author(s):

Yong June Choi ◽

Kyung Mun Kang ◽

Hyung Ho Park

Keyword(s):

Thin Films ◽

Surface Roughness ◽

Atomic Layer Deposition ◽

Morphological Changes ◽

Atomic Layer ◽

Root Mean Square Roughness ◽

Post Annealing ◽

Layer Deposition ◽

Annealing Effects ◽

Doped Zno

The post-annealing effects on the surface morphological changes of undoped and Al-doped ZnO (ZnO:Al) thin films deposited by atomic layer deposition (ALD) were investigated. The as-grown films were deposited by ALD at growth temperature of 200°C and also, post-annealing of the samples was accomplished at 300°C for 1 h under nitrogen atmosphere. The X-ray diffraction of the films was monitored to study the crystallinity of the films according to post-anneal. The field emission-scanning electron microscopy and atomic force microscopy were conducted to observe the surface morphological changes and measure the root-mean-square roughness of the films in order to analysis the post-annealing effects on the surface roughness of the films.

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A Thermodynamic Investigation of Ni on Thin-Film Titanates (ATiO3)

Inorganics ◽

10.3390/inorganics8120069 ◽

2020 ◽

Vol 8 (12) ◽

pp. 69

Author(s):

Chao Lin ◽

Alexandre C. Foucher ◽

Eric A. Stach ◽

Raymond J. Gorte

Keyword(s):

Atomic Layer Deposition ◽

Coulometric Titration ◽

Equilibrium Constants ◽

Atomic Layer ◽

Co2 Reforming ◽

Co2 Reforming Of Ch4 ◽

Transmission Electron ◽

Layer Deposition ◽

Ni Oxidation ◽

Scanning Transmission

Thin, ~1-nm films of CaTiO3, SrTiO3, and BaTiO3 were deposited onto MgAl2O4 by Atomic Layer Deposition (ALD) and then studied as catalyst supports for ~5 wt % of Ni that was added to the perovskite thin films by Atomic Layer Deposition. Scanning Transmission Electron Microscopy demonstrated that both the Ni and the perovskites uniformly covered the surface of the support following oxidation at 1073 K, even after redox cycling, but large Ni particles formed following a reduction at 1073 K. When compared to Ni/MgAl2O4, the perovskite-containing catalysts required significantly higher temperatures for Ni reduction. Equilibrium constants for Ni oxidation, as determined from Coulometric Titration, indicated that the oxidation of Ni shifted to lower PO2 on the perovskite-containing materials. Based on Ni equilibrium constants, Ni interactions are strongest with CaTiO3, followed by SrTiO3 and BaTiO3. The shift in the equilibrium constant was shown to cause reversible deactivation of the Ni/CaTiO3/MgAl2O4 catalyst for CO2 reforming of CH4 at high CO2 pressures, due to the oxidation of the Ni.

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