2026-08-08T16:08:19Z https://journal.atomiclayerdeposition.com/oai.php

10.3897/aldj.1.101276 2023-03-27 atomiclayerdeposition

Transformation kinetics for low temperature post-deposition crystallization of TiO 2 thin films prepared via atomic layer deposition (ALD) from tetrakis(dimethylamino)titanium(IV) (TDMAT) and water Wooding,Jamie Gregory,Shawn Atassi,Amalie Freychet,Guillaume Kalaitzidou,Kyriaki Losego,Mark Nucleation and Growth Microstructure TiO2 crystal growth anatasex-ray diffraction (XRD) Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation Thin Film growth kinetics phase transformation Atomic Layer Deposition 1: 1-18 Background: We report on the fundamental crystallization kinetics of atomic layer deposited (ALD) TiO2 thin films undergoing a post-deposition anneal (PDA) at low temperatures to probe differences in the as-deposited film microstructure. Methods: The system of study is ALD TiO2 thin films prepared from tetrakis(dimethylamino)titanium(IV) (TDMAT) and water at 120 °C, 140 °C and 160 °C followed by ex situ low temperature annealing at temperatures ranging from 140 °C to 220 °C. All as-deposited TiO2 thin films are amorphous by X-ray diffraction (XRD). Post-deposition annealing (PDA) produces large grain anatase crystals, confirmed by XRD and top-view scanning electron microscopy (SEM). A detailed SEM study is performed to quantify the nucleation and growth kinetics by fitting microstructural data to the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. Finally, a time-temperature-transformation (TTT) diagram is constructed to summarize the differences in crystallization behavior at different ALD deposition temperatures. Results and conclusions: Fitting microstructural data to the JMAK equation reveals an Avrami exponent close to 3 with continuous nucleation, suggesting two-dimensional, plate-like crystal growth. Applying an Arrhenius relationship to the phase transformation data, the combined activation energy for nucleation and growth is found to be 1.40–1.58 eV atom-1. Nucleation rates are determined, and an Arrhenius relationship is used to calculate the critical Gibbs free energy for nucleation (~1.3–1.4 eV atom-1). As such, nucleation is the rate-limiting step for the amorphous to anatase phase transformation. ALD growth temperature is found to dictate film microstructure with lower deposition temperatures reducing the nucleation rate and leading to larger grain sizes irrespective of PDA conditions. The nucleation rate pre-exponential frequency factor increases with increasing deposition temperature, thereby increasing the likelihood for nucleation. Interestingly, it is this difference in the vibrational modes of the amorphous structure, as indicated by the variation in the nucleation rate pre-exponential frequency factor, that alters the phase transformation rates and not a change in the activation energies for the transformation. info:eu-repo/semantics/altIdentifier/eissn/2772-2570 info:eu-repo/semantics/openAccess CC BY 4.0 Ultimaterials Netherlands BV 2023 Research Article text/html info:doi:10.3897/aldj.1.101276 https://doi.org/10.3897/aldj.1.101276 https://journal.atomiclayerdeposition.com/article/101276/ https://journal.atomiclayerdeposition.com/article/101276/download/pdf/ en

10.3897/aldj.1.101651 2023-03-27 atomiclayerdeposition

Atmospheric-pressure plasma-enhanced spatial atomic layer deposition of silicon nitride at low temperature Shen,Jie Roozeboom,Fred Mameli,Alfredo Spatial ALD silicon nitride (SiNx) spatial atomic layer deposition atmospheric pressure low temperature (250 °C) Atomic Layer Deposition 1: 1-11 Atmospheric-pressure plasma-enhanced spatial atomic layer deposition (PE-spatial-ALD) of SiNx is demonstrated for the first time. Using bis(diethylamino)silane (BDEAS) and N2 plasma from a dielectric barrier discharge source, a process was developed at low deposition temperatures (≤ 250 °C). The effect of N2 plasma exposure time and overall cycle time on layer composition was investigated. In particular, the oxygen content was found to decrease with decreasing both above-mentioned parameters. As measured by depth profile X-ray photoelectron spectroscopy, 4.7 at.% was the lowest oxygen content obtained, whilst 13.7 at.% carbon was still present at a deposition temperature of 200 °C. At the same time, deposition rates up to 1.5 nm/min were obtained, approaching those of plasma enhanced chemical vapor deposition and thus opening new opportunities for high-throughput atomic-level processing of nitride materials. info:eu-repo/semantics/altIdentifier/eissn/2772-2570 info:eu-repo/semantics/openAccess CC BY 4.0 Ultimaterials Netherlands BV 2023 Research Article text/html info:doi:10.3897/aldj.1.101651 https://doi.org/10.3897/aldj.1.101651 https://journal.atomiclayerdeposition.com/article/101651/ https://journal.atomiclayerdeposition.com/article/101651/download/pdf/ en

10.3897/aldj.1.105146 2023-08-07 atomiclayerdeposition

Robust surface functionalization of PDMS through atmospheric pressure atomic layer deposition Santoso,Albert van den Berg,Bart J. Saedy,Saeed Goodwin,Eden van Steijn,Volkert Van Ommen,J. Ruud PDMS Atmospheric ALD Titanium dioxide wettability functionalization Atomic Layer Deposition 1: 1-13 Polydimethylsiloxane (PDMS) has been widely employed as a material for microreactors and lab-on-a-chip devices. However, in its applications, PDMS suffers from two major problems: its weak resistance against common organic solvents and its chemically non-functional surface. To overcome both issues, atmospheric pressure atomic layer deposition (AP-ALD) can be used to deposit an inorganic nanolayer (TiOx) on PDMS that, in turn, can be further functionalized. The inorganic nano layer is previously communicated to durably increase the organic solvent resistance of PDMS. In this study, we investigate the possibility of this TiOx nano layer providing surface anchoring groups on PDMS surfaces, enabling further functionalization. We treat PDMS samples cured at three different temperatures with AP-ALD and measure the hydrophilicity of the treated samples as an indicator of the presence of surface anchoring groups. We find that all the treated PDMS samples become hydrophilic right after the AP-ALD treatment. We further find that the AP-ALD-treated PDMS samples cured at 150 °C and 200 °C maintain their hydrophilicity, while the samples cured at 70 °C become less hydrophilic over time. The presence of surface anchoring groups through TiOx nano layer deposition on PDMS is further demonstrated and utilized by depositing gold nanoparticles (AuNPs) on the AP-ALD-treated samples. The samples exhibit visible light absorbance at 530 nm, a typical absorbance peak for AuNPs. In conclusion, this study demonstrates the use of nano layers grown by AP-ALD to solve the two major problems of PDMS simultaneously, widening its applicability, especially for use in high-end applications such as catalysis and bio-sensing. info:eu-repo/semantics/altIdentifier/eissn/2772-2570 info:eu-repo/semantics/openAccess CC BY 4.0 Ultimaterials Netherlands BV 2023 Research Article text/html info:doi:10.3897/aldj.1.105146 https://doi.org/10.3897/aldj.1.105146 https://journal.atomiclayerdeposition.com/article/105146/ https://journal.atomiclayerdeposition.com/article/105146/download/pdf/ en

10.3897/aldj.2.117753 2024-06-04 atomiclayerdeposition

Crystalline as-deposited TiO 2 anatase thin films grown from TDMAT and water using thermal atomic layer deposition with in situ layer-by-layer air annealing Wooding,Jamie Kalaitzidou,Kyriaki Losego,Mark Atomic layer deposition TiO2 anatase crystallization thin films Atomic Layer Deposition 2: 1-18 We report a new thermal atomic layer deposition (thermal-ALD) process including an air exposure as a third precursor to deposit crystalline TiO2 anatase thin films from tetrakis(dimethylamido)titanium(IV) (TDMAT) and water at deposition temperatures as low as 180 °C and film thicknesses as low as 10 nm. This ALD process enables TiO2-antase crystal growth during the deposition at low temperatures (< 220 °C). This additional oxidant pulse is used to fully oxidize the Ti to a 4+ state in the amorphous film, lowering the barrier to crystalline anatase formation. This new approach is informed by preliminary studies of post-deposition annealing (PDA) of thermal ALD films in both nitrogen and air atmospheres, which demonstrate the importance of having an oxidizing atmosphere to achieve the nucleation of the crystalline anatase phase. This oxidizing atmosphere is subsequently introduced into the ALD cycle as a third precursor and is shown to be more effective and efficient in promoting the crystalline transformation than even by post-deposition annealing. The crystalline anatase phase is verified by Raman spectroscopy and grazing incidence X-ray diffraction (GIXRD). The mechanism for crystallization during the TDMAT/H2O/air ALD cycle is probed by chemical state analysis via X-ray photoelectron spectroscopy (XPS). We propose that sub-oxidation in TiO2 thin films deposited by the thermal-ALD process inhibits crystallization during ALD from TDMAT/H2O chemistry. Scanning electron microscopy (SEM) is used to investigate the microstructure of these TiO2 thin films as a function of thickness (5 nm to 50 nm) and deposition temperature (180 °C to 220 °C). The reported layer-by-layer air anneal process is found to crystallize entire films in shorter total process times than thermal-ALD with ex situ post deposition annealing at identical temperatures, presumably due to the improved surface diffusion kinetics accessed during the deposition process. info:eu-repo/semantics/altIdentifier/eissn/2772-2570 info:eu-repo/semantics/openAccess CC BY 4.0 Ultimaterials Netherlands BV 2024 Research Article text/html info:doi:10.3897/aldj.2.117753 https://doi.org/10.3897/aldj.2.117753 https://journal.atomiclayerdeposition.com/article/117753/ https://journal.atomiclayerdeposition.com/article/117753/download/pdf/ en