High aqueous chemical solution deposition

In our research, we have applied aqueous chemical solution deposition [38,39] to the screening of several candidate high-x dielectric materials such as Zr02, rare... 

The authors would like to thank prof dr. Stefan De Gendt and dr. Sven Van Ekhocht (imec, Leuven) for the joint work on ultrathin high-k dielectrics from aqueous chemical solution deposition. 

Aqueous chemical solution deposition a fast screening method for alternative high-k materials applied to Nd20s as a case study. Electrochem. Solid-State Lett, 10, G15-G17. 

Richard, O., Van Bael, MX., Mullens, J, and De Gendt, S. (2008) Impact of process optimization on the electiical performance of high-k layers deposited by aqueous chemical solution deposition. /. Electrochem. 

Very acidic (high valent) cations will readily hydrolyse in aqueous solution, often even at low pH. These cations tend to form the polymeric metal oxide chains mentioned previously. This hydrolysis can be controlled by addition of boric acid (see Sec. 3.2.4.4) and forms the basis of a technique referred to as liquid phase deposition. This method can be reasonably included in the more general term of chemical solution deposition, and is treated, although not comprehensively, in this book. Ref 5 deals more thoroughly with this technique and describes many cases of SiOi as well as some examples of several other oxides not covered in this chapter. 

Zinc sulfide, with its wide band gap of 3.66 eV, has been considered as an excellent electroluminescent (EL) material. The electroluminescence of ZnS has been used as a probe for unraveling the energetics at the ZnS/electrolyte interface and for possible application to display devices. Fan and Bard [127] examined the effect of temperature on EL of Al-doped self-activated ZnS single crystals in a persulfate-butyronitrile solution, as well as the time-resolved photoluminescence (PL) of the compound. Further [128], they investigated the PL and EL from single-crystal Mn-doped ZnS (ZnS Mn) centered at 580 nm. The PL was quenched by surface modification with U-treated poly(vinylferrocene). The effect of pH and temperature on the EL of ZnS Mn in aqueous and butyronitrile solutions upon reduction of per-oxydisulfate ion was also studied. EL of polycrystalline chemical vapor deposited (CVD) ZnS doped with Al, Cu-Al, and Mn was also observed with peaks at 430, 475, and 565 nm, respectively. High EL efficiency, comparable to that of singlecrystal ZnS, was found for the doped CVD polycrystalline ZnS. In all cases, the EL efficiency was about 0.2-0.3%. 

Zinc nitrate (Zn(N03)2) and dimethylamine borane (DMAB) with a reagent grade from Sigma-Aldrich were used to synthesize the thin film of ZnO on the Pt-IPMC electrodes. The chemical deposition method was used because the conventional methods such as metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), and DC or RF sputtering require temperatures from 200 °C to 800 °C, while IPMC could not withstand such high temperatures. ZnO thin films were synthesized on the Pt IPMC in an aqueous solution composed of 0.1 mol/L zinc nitrate hydrous and 0.1 mol/L DMAB maintained at 60 °C. As the electrical and optical properties of ZnO film depend on the DMBA concentration. ZnO film prepared from the 0.1 mol/L DMAB solution showed the best results. The optimum deposition condition for ZnO as reported in [Izaki and Katayama (2000)] was used. 

The homopolymer films of sulfonated poly(3,4-ethylenedioxythio-phene) were electrochemically polymerized using a mixture of acetonitrile and water (5 1 ratio), as reported by Kumar et al. [31]. The UV-Vis spectra and the molecular weight of 15 800 g/mol confirmed the polymeric nature of the deposited films. The polymer was found to be soluble in water. The electrochemical and chemical synthesis of water-soluble, highly conductive oligomers of sulfonated poly(3,4-ethylenedioxythiophene) in aqueous acid and nonaqueous media has been reported by Zotti et al. [32]. In aqueous HCIO4 solution, the constant potential electrolysis of the sodium salt of sulfonated... 

Polyaniline has also been deposited by in situ polymerization (chemically or electrochemically) as thin films or coatings (in the form of ES) on a variety of substrates such as glass slides, metal films, natural or synthetic fibers, and textiles, [25,26]. In the chemical oxidation process, the substrate was immersed in a newly prepared aqueous acidic solution containing aniline and ammonium peroxydisul-fate. The material deposited during the first 1-2 min was in the highly oxidized state and later changed into the oxidation state of emeraldine salt after —10 min [26]. 

Alpha alumina (a-Al203) powders can be synthesized by different high temperature methods, such as the Bayer process, heat treatment of gel-based Al(OH)3, high-temperature decomposition of aluminum containing salts, and chemical vapor deposition (CVD) [28]. Hydrothermal synthesis is a low temperature alternative to the methods described above and crystallizes anhydrous materials in many forms directly from aqueous solutions at temperatures up to 300 °C and high pressures [29]. 

Yoshikawa et al. have found that highly conductive polypyrrole could be obtained if the oxidation potential of the aqueous solution is controlled to the optimum value during chemical polymerization by adding a suitable amount of FeCl2. In this way polypyrrole having a conductivity of more than 200 S cm has been prepared [25]. When this procedure is applied to chemical vapor deposition, polypyrrole having a conductivity more than 100 S cm is obtained [26]. 

Acid-developable photoresists mentioned in the dry-film aqueous section can also be formulated as electrophoretic-depositable liquids. These materials have high contrast, good resolution, and chemical stability in strongly alkaline solutions since they are developed in aqueous acid solutions. 

Ionic liquids are interesting media for the electrodeposition of metals, alloys, and senoiconductors, despite the fact that they are more expensive than aqueous baths. Due to their large electrochemical windows and their good thermal and chemical stability, they are used nowadays to electrodeposit metals that can also be obtained from aqueous solution, such as Cr, Ag, Ni, Cu, but also to electrodeposit metals that cannot be obtained from aqueous baths. This paper deals with the electrodeposition of Si and Ta in the ionic liquid butyl-methyl-pyrrolidinium bis(trifluoro)sulfonyl imide ([BMP][TFSI]). Compared to other deposition techniques, such as chemical vapor deposition or plasma vapor deposition, electrodeposition is a relatively simple technique and in many cases significantly cheaper. Moreover, materials of different shapes and dimensions can be obtained relatively easy by electrodeposition. Thus, for industrial applications, it would be highly interesting to obtain reactive metals and semiconductors by electrodeposition. 

Recently, some innovative plasma-spray techniques have been employed to produce TBCs with lower thermal conductivities and more durable performance. The solution precursor plasma spray (SPPS) has been exploited to deposit TBCs, in which an aqueous chemical precursor feedstock, rather than YSZ powders, is injected into plasma jet [25,26]. The lack of large-scale splat boundaries effectively toughens the TBCs, making SPPS TBCs highly durable relative to APS TBCs. 

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