Three-step Deposition Process Research Articles

Three-step deposition process for improved nucleation of noble metal thin films

A three-step atomic layer deposition process tested with ruthenium could hold the key to creating continuous and smooth noble metal thin films.

Epitaxial growth of Pd1−xFex films on MgO single-crystal substrate

In the paper we report on growth conditions, morphology, crystallographic structure and magnetic anisotropy of 20 nm thick, palladium-rich Pd1−xFex (0.01 < x < 0.1) alloy films grown on (001)-oriented MgO single-crystal substrate. Molecular beam deposition at ultra-high vacuum conditions has been utilized along with the three-step procedure to achieve the epitaxy conditions for the synthesized films. The scanning electron microscopy and atomic force microscopy have shown flat and smooth morphology of the films studied in a wide range of lateral scales. Insitu low energy electron diffraction and exsitu X-ray diffraction measurements confirmed that our Pd1−xFex alloy films are epitaxial. Ferromagnetic resonance investigations have shown the in-plane four-fold magnetocrystalline anisotropy characteristic for single-crystalline films with the cubic structure. The whole set of our measurements testifies the epitaxial cube-on-cube growth and excellent magnetic homogeneity of Pd1−xFex films on MgO substrate obtained within the three-step deposition process.

Template-dealloying synthesis of ultralow density Au foams with bimodal porous structure

Noble metallic foams with low density are desirable in high energy-density physical experiments. In this study, Au foams with ultralow density were successfully synthesized from a template-dealloying approach. Microspherical polystyrene (PS) was employed as the sacrificial template. Au and Ag nanoparticles were sequentially coated onto the PS surface from a three-step deposition process. Cylindrical PS/Au/Ag monoliths were formed by filter-casting of the nanoparticle coated PS suspension. The templates were removed and Au–Ag alloy foams were generated after calcination at 400 °C. Self-supported Au foams with bimodal porous structure were produced by dealloying of the less noble Ag component. Au foam with density as low as 0.36 g cm−3 can be achieved, which demonstrates high surface area of 23.6 m2 g−1 and pore volume of 0.15 m3 g−1.

A novel, substrate independent three-step process for the growth of uniform ZnO nanorod arrays

We report a three-step deposition process for uniform arrays of ZnO nanorods, involving chemical bath deposition of aligned seed layers followed by nanorod nucleation sites and subsequent vapour phase transport growth of nanorods. This combines chemical bath deposition techniques, which enable substrate independent seeding and nucleation site generation with vapour phase transport growth of high crystalline and optical quality ZnO nanorod arrays. Our data indicate that the three-step process produces uniform nanorod arrays with narrow and rather monodisperse rod diameters (∼ 70 nm) across substrates of centimetre dimensions. X-ray photoelectron spectroscopy, scanning electron microscopy and X-ray diffraction were used to study the growth mechanism and characterise the nanostructures.

Process and properties of the carbon nanotube assisted LiCoO2 thin-film battery electrode by pulsed laser deposition

In this study, a pulsed laser deposition process was developed to deposit a carbon nanotube (CNT) assisted LiCoO2 electrode to improve its power density. The electrodes were deposited on Pt-coated Si substrates with Ar and O2 as sputtering gases and LiCoO2+C as the target. The results indicate that the working pressure is the most important parameter to control the composition of the electrode. Therefore, electrodes with a three-layer structure (i.e., LiCoO2-rich/CNT-rich/LiCoO2-rich) were fabricated by a three-step deposition process by varying the pressures from 13 to 1.3×104 Pa and then 13 Pa again, and it was found that the charge/discharge capacity became approximately 1.5 times greater than that in the corresponding electrode without a CNT-rich layer. The results also indicate that a higher substrate temperature is favorable for improving the crystallinity of the electrode to approach LiCoO2 crystals.

Epitaxial growth of Cu(100) and Pt(100) thin films on perovskite substrates

Pulsed laser deposition has been used to grow epitaxially oriented thin films of Cu and Pt on (100)-oriented SrTiO 3 and LaAlO 3 substrates. X-ray diffraction results illustrated that purely epitaxial Cu(100) films could be obtained at temperatures as low as 100 °C on SrTiO 3 and 300 °C on LaAlO 3. In contrast, epitaxial (100)-oriented Pt films were attained on LaAlO 3(100) only when deposited at 600 °C. Atomic force microscopy images showed that films deposited at higher temperatures consisted of 3D islands and that flat, layered films were obtained at the lowest deposition temperatures. Importantly, Cu films deposited at 100 °C on SrTiO 3(100) were both purely (100)-oriented and morphologically flat. Pt and Cu films displaying both epitaxial growth and smooth surfaces could be obtained on LaAlO 3(100) only by using a three-step deposition process. High-resolution transmission electron microscopy demonstrated an atomically sharp Cu/SrTiO 3 interface. The crystalline and morphological features of Cu and Pt films are interpreted in terms of the thermodynamic and kinetic properties of these metals.

Homogeneous silica coating of vitreophobic colloids

Gold colloids are homogeneously coated with silica via a three-step deposition process; the thickness of the silica layer can be completely controlled, and the particles can be transferred into practically any solvent.