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Multiple layers of aluminum silicate and SiO2 are deposited at room temperature (RT) by repeating a combination of aluminum-silicate atomic layer deposition (ALD) and a plural number of SiO2 ALDs. The RT-ALD is performed by using precursors of tris(dimethylamino)silane and trimethyl aluminum (TMA). The oxidizing gas is plasma excited humidified Ar. A cross-sectional transmission electron microscope and angle resolved x-ray photoelectron spectroscopy suggest that aluminum from the TMA molecule is diffused to SiO2 to form an aluminum silicate layer with the Al rich surface at RT. The deposited film shows an enhanced Na sorption in an NaCl aqueous solution of 10 mM, compared with the pure aluminum silicate layer without the SiO2 layer. It is assumed that the bond formation of Al–O–Al in the aluminum silicate film is suppressed by limiting the thickness of the aluminum silicate layer. Multiple films are also applicable for Cs and K ion sorption. The effects of the multiple layers on the ion sorptivity are discussed in the paper. [ABSTRACT FROM AUTHOR]

Room-temperature atomic layer deposition (RT-ALD) of iron oxide is developed with a precursor of bis(N, N′-diisopropyl-propionamidinate)iron [(DIPPA)2Fe] and plasma excited humidified Ar. Saturated conditions of (DIPPA)2Fe and plasma excited humidified Ar exposures at room temperature (23–25 °C) are investigated by in situ IR absorption spectroscopy for finding the RT-ALD process condition. Using the designated process, the growth per cycle of the iron oxide RT-ALD is confirmed as 0.15 nm/cycle based on the film thicknesses measured by the spectroscopic ellipsometer. The x-ray photoelectron spectroscopy suggests that the stoichiometry of the deposited iron oxide is closed to that of Fe2O3. The grown film is composed of partly crystallized iron oxides, confirmed by cross-sectional TEM and AFM. The RT deposited iron oxide exhibits a magnetic volume susceptibility of 1.52, which implies the applicability of the present coating for magnetic drug delivery. We discuss the surface reaction with the IR absorption spectroscopy and the quartz crystal microbalance. The (DIPPA)2Fe molecule is suggested to adsorb on the Fe2O3 surface with mixed first- and second-order reactions at RT. It is also suggested that amidinate ligands in (DIPPA)2Fe are released in the course of the adsorption and the remaining ligands are oxidized by the plasma excited humidified Ar. The RT iron oxide deposition is demonstrated, and the reaction mechanism of room-temperature ALD is discussed in this paper. [ABSTRACT FROM AUTHOR]

Room temperature (RT) atomic layer deposition (ALD) of Nb2O5 is developed using (tert-butylimido)tris(ethylmethylamido)niobium and a plasma excited humidified Ar. To design the process condition, an in situ monitoring system of IR absorption spectroscopy (IRAS) is utilized to observe the surface saturation of precursors. Based on the saturation characteristics of precursors measured from IRAS, the gas injection condition and oxidization time are determined, where the RT Nb2O5 deposition with a growth per cycle of 0.11 nm is confirmed by x-ray photoelectron spectroscopy and spectroscopic ellipsometry. The RT deposited Nb2O5 film exhibits clear anticorrosion to hydrochloric acid. The reaction mechanism of ALD growth and the applicability of anticorrosion film with RT deposited N2O5 are discussed in this paper. [ABSTRACT FROM AUTHOR]

Room temperature (RT) atomic layer deposition (ALD) of ZnO is developed by using a precursor of dimethyl zinc (DMZ) and plasma excited humidified argon. Surface reactions of RT ALD of ZnO are investigated by an in situ observation of multiple internal reflection IR absorption spectroscopy. The saturation condition of DMZ and plasma excited humidified argon is discussed by the IR absorbance spectra measured from the sample surface. In the ALD experiment, the grown film is identified as the fully oxidized ZnO by x-ray photoelectron spectroscopy. The growth per cycle is measured to be 0.046 nm/cycle. In this paper, the authors will discuss the mechanism of surface reaction in the ALD process. [ABSTRACT FROM AUTHOR]

The authors present a plasma enhanced room-temperature atomic layer deposition (ALD) technique for depositing aluminum silicate on TiO2 photoanodes for dye-sensitized solar cells. In the ALD process, adsorption of the precursor is completed in a two-step process involving sequential application of a subsaturation quantity of tris(dimethylamino)silane (TDMAS) and an Al precursor trimethylaluminum to the target surface. The Al-to-Si atomic ratio is controlled by the initial coverage of TDMAS on the sample surface. Aluminum-silicate coatings with a balanced composition of Al and Si are applied to the TiO2 nanoparticle photoanodes in N719-based dye-sensitized solar cells. A one-cycle ALD coating improves the short circuit current density, suggesting the enhancement of N719 dye adsorption or charge separation at the interface of the dye and TiO2 photoanode. Electro-impedance analysis suggests that the improved power generation does not correlate with the charge recombination of electrons in TiO2 and I3 - ions in the redox electrolyte. The mechanism behind the improvement in the coated photoanode samples is discussed in this paper. [ABSTRACT FROM AUTHOR]

The authors developed a room temperature atomic layer deposition (ALD) system that can deposit TiO2 on gold nanoparticles by using tetrakis(dimethylamino)titanium and plasma-excited humidified argon. The growth per cycle of TiO2 was measured to be 0.25 nm/cycle on a monitored Si sample. For applying the nanoparticle coating, the source material, i.e., gold particles, is electrostatically attached to the susceptor in the ALD system to avoid their gas transport. These particles are then mixed by a rotating scraper during the ALD process. This system allows a conformal deposition of TiO2 without the aggregation of nanoparticles. The thickness of TiO2 for shell coating is controlled by counting the number of ALD cycles. The deposition of TiO2 coating with a nanometer scale thickness on the gold nanoparticle is demonstrated in this paper. [ABSTRACT FROM AUTHOR]