Atomic layer deposition (ALD) is gaining attention as a thin film deposition method, uniquely suitable for depositing uniform and conformal films on complex three-dimensional topographies. The deposition of a film of a given material by ALD relies on the successive, separated, and self-terminating gas–solid reactions of typically two gaseous reactants. Hundreds of ALD chemistries have been found for depositing a variety of materials during the past decades, mostly for inorganic materials but lately also for organic and inorganic–organic hybrid compounds. One factor that often dictates the properties of ALD films in actual applications is the crystallinity of the grown film: Is the material amorphous or, if it is crystalline, which phase(s) is (are) present. In this thematic review, we first describe the basics of ALD, summarize the two-reactant ALD processes to grow inorganic materials developed to-date, updating the information of an earlier review on ALD [R. L. Puurunen, J. Appl. Phys. 97, 121301 (2005)], and give an overview of the status of processing ternary compounds by ALD. We then proceed to analyze the published experimental data for information on the crystallinity and phase of inorganic materials deposited by ALD from different reactants at different temperatures. The data are collected for films in their as-deposited state and tabulated for easy reference. Case studies are presented to illustrate the effect of different process parameters on crystallinity for representative materials: aluminium oxide, zirconium oxide, zinc oxide, titanium nitride, zinc zulfide, and ruthenium. Finally, we discuss the general trends in the development of film crystallinity as function of ALD process parameters. The authors hope that this review will help newcomers to ALD to familiarize themselves with the complex world of crystalline ALD films and, at the same time, serve for the expert as a handbook-type reference source on ALD processes and film crystallinity.

Crystallinity of inorganic films grown by atomic layer deposition: Overview and general trends

Synthesis of nanoparticles in the gas phase for electronic, optical and magnetic applications—a review

Surface Chemistry of Ruthenium Dioxide in Heterogeneous Catalysis and Electrocatalysis: From Fundamental to Applied Research

In real life applications, supercapacitors (SCs) often can only be used as part of a hybrid system together with other high energy storage devices due to their relatively lower energy density in comparison to other types of energy storage devices such as batteries and fuel cells. Increasing the energy density of SCs will have a huge impact on the development of future energy storage devices by broadening the area of application for SCs. Here, we report a simple and scalable way of preparing a three-dimensional (3D) sub-5 nm hydrous ruthenium oxide (RuO2) anchored graphene and CNT hybrid foam (RGM) architecture for high-performance supercapacitor electrodes. This RGM architecture demonstrates a novel graphene foam conformally covered with hybrid networks of RuO2 nanoparticles and anchored CNTs. SCs based on RGM show superior gravimetric and per-area capacitive performance (specific capacitance: 502.78 F g−1, areal capacitance: 1.11 F cm−2) which leads to an exceptionally high energy density of 39.28 Wh kg−1 and power density of 128.01 kW kg−1. The electrochemical stability, excellent capacitive performance, and the ease of preparation suggest this RGM system is promising for future energy storage applications.

https://cyberleninka.org/article/n/529338.pdf

Hydrous Ruthenium Oxide Nanoparticles Anchored to Graphene and Carbon Nanotube Hybrid Foam for Supercapacitors

Atomic layer deposition (ALD) is an attractive method to deposit thin films for advanced technological applications such as microelectronics and nanotechnology. One material group in ALD that has matured in 10 years and proven to be of wide technological importance is noble metals. In this paper, thermal ALD of noble metals and their oxides is reviewed. Noble metal films are mostly grown using O2 as the nonmetal precursor in a combustion-type chemistry. Alternatively, lower growth temperatures can be reached via noble metal oxide growth with consecutive reactions with ozone and H2. The use of true reducing chemistry (i.e., H2) is typical only for ALD of palladium at low temperatures. On the other hand, ALD of noble metal oxides has been limited with reactants such as ozone and O2 gas. In this review, reaction mechanisms in various types of processes are discussed and issues in nucleation are addressed. Deposition temperatures, film growth rates, and purities as well as evaporation temperatures used for no...

Atomic Layer Deposition of Noble Metals and Their Oxides

Titanium dioxide thin films were grown on RuO 2 layers by atomic layer deposition. The stabilizing effect of the bottom rutile-type RuO 2 layer resulted in growth of the TiO 2 rutile films at temperatures above 275°C. Stabilization of the TiO 2 rutile phase occurred due to local epitaxial growth of the polycrystalline RUO 2 /TiO 2 /RUO 2 structure, as revealed by transmission electron microscopy. A dielectric constant as high as 155 and equivalent oxide thickness (EOT) as low as 0.5 nm were determined from the capacitance-voltage measurements for the TiO 2 films grown above 275°C. A leakage current density of 10 -3 A/cm 2 at 1 V bias voltage was obtained for the films with EOT equal to 0.5 nm.

Growth of High-Dielectric-Constant TiO2 Films in Capacitors with RuO2 Electrodes

Polycrystalline and epitaxial RuO2∕TiO2∕RuO2 structures were prepared by a combination of metal organic chemical vapor deposition and atomic layer deposition techniques. TiO2 layer grew in a rutile structure due to epitaxial growth on the RuO2 seed layer and exhibited high dielectric constant of 120. Equivalent oxide thickness as low as 0.5nm with a leakage current density of 6×10−6A∕cm2 at 0.8V bias voltage was obtained for the RuO2∕TiO2∕RuO2 capacitor structure epitaxially grown on (11¯02) sapphire substrate. Analysis of leakage currents revealed uneven distribution of defects in the TiO2 dielectric layer.

Epitaxial growth of high-κ TiO[sub 2] rutile films on RuO[sub 2] electrodes

LSMO thin films with high metal–insulator transition temperature on buffered SOI substrates for uncooled microbolometers

Characterization of rare earth oxides based MOSFET gate stacks prepared by metal-organic chemical vapour deposition

In this work, we systematically studied the influence of the plasma treatment (PT) on the structural and electrical properties of Pt/rutile-TiO2/RuO2 metal–insulator–metal capacitors. The leakage current of the 12 nm thick TiO2 dielectrics prepared by atomic layer deposition was reduced below 10−7 A cm−2 while the capacitance equivalent thickness was kept below 0.5 nm using oxygen PT of the bottom RuO2 electrode. Reflection high energy electron diffraction, transmission electron microscopy, atomic force microscopy and x-ray photoelectron spectroscopy analyses allowed the conclusion that O2 plasma smoothened the RuO2 surface and increased its oxygen content through plasma induced surface reconstruction. The nucleation of TiO2 on the plasma-treated surface was faster while the thickness of the capacitor dead layer at the TiO2/RuO2 interface was reduced.

https://iopscience.iop.org/article/10.1088/0022-3727/46/38/385304/pdf

Alica Rosová

Papers

Growth of High-Dielectric-Constant TiO2 Films in Capacitors with RuO2 Electrodes

Epitaxial growth of high-κ TiO[sub 2] rutile films on RuO[sub 2] electrodes

LSMO thin films with high metal–insulator transition temperature on buffered SOI substrates for uncooled microbolometers

Characterization of rare earth oxides based MOSFET gate stacks prepared by metal-organic chemical vapour deposition

Impact of plasma treatment on electrical properties of TiO2/RuO2 based DRAM capacitor