Thin Film Deposition Methods Research Articles

Nanostructured thin film coatings with different strengthening effects

A number of articles on strengthening thin film coatings were analyzed and a lot of unusual strengthening effects, such as super high hardness and plasticity simultaneously, ultra low friction coefficient, high wear-resistance, curve rigidity increasing of drills with small diameter, associated with process formation of nanostructured coatings by the different thin film deposition methods were detected. Vacuum coater with RF magnetron sputtering system and ion-beam source and arc evaporator for nanostructured thin film coating manufacture are represented. Diamond Like Carbon and MoS 2 thin film coatings, Ti, Al, Nb, Cr, nitride, carbide, and carbo-nitride thin film materials are described as strengthening coatings.

Low temperature depositions of GaN thin films by plasma-enhanced atomic layer deposition

Metalorganic chemical vapour deposition and molecular beam epitaxy have already been demonstrated to be successful techniques for obtaining high-quality epitaxial GaN layers with low impurity concentrations and pretty good electrical properties. However, high growth temperature employed in both of these methods give rise to some intrinsic defects of the thin films, such as high background-carrier concentrations. As a low-temperature thin film deposition method, plasma-enhanced atomic layer deposition (PE-ALD) has more unique advantages compared to both methods for epitaxial growth of GaN. In this paper, the polycrystalline GaN thin films were fabricated on Si (100) substrates at 150-300℃ by PE-ALD. Trimethylgallium and N2/H2 plasma gas mixture were used as the Ga and N precursors. The growth rate of the thin films was demonstrated by the spectroscopic ellipsometer. The crystal structrue and composition of the GaN thin films were characterized by X-ray diffractometer and X-ray photoelectron spectrometer (XPS). It is showed that the growth window for PE-ALD grown GaN thin films is 210-270℃, where the growth rate remains constant at 0.70 /cycle. And it is known that it is the self-limiting nature of PE-ALD that is ascribed to the plateau of the growth rate. Films grown at relatively higher temperature are polycrystalline with a hexagonal wurtzite structure, while films grown under relatively lower temperature are amorphous. The grazing incidence X-ray diffraction (GIXRD) patterns of the polycrystalline thin films reveal three main peaks located at 2=32.4, 34.6 and 36.9, which are corresponding to the (100), (002) and (101) reflections. It is showed that the Ga, N atoms would get higher energy for more effective migration to positions with lowest energy to form ordered crystalline arrange at higher growth temperature. The XPS results show that all the N elements of the as-grown thin films are in the form of NGa bond, indicating that all the N elements are formed into GaN thin films; and there is a little amount of the Ga elements that exist in GaO bond. The fact that there is no Ga2O3-related peaks in the GIXRD pattern suggests that there is small amount of amorphous Ga2O3 dispersed in the polycrystalline GaN thin films. In the future work, reducing the concentration of the C and O impurities may be achieved by increasing the time of the reaction and plasma pules in the process formula and replacing the inductively coupled plasma with the hollow cathode plasma, respectively.

New amidinate complexes of indium(iii): promising CVD precursors for transparent and conductive In2O3 thin films.

For the first time, synthesis of two new amidinate-ligand comprising heteroleptic indium complexes, namely [InCl(amd)2] (1) and [InMe(amd)2] (2), via salt-metathesis and their detailed characterization is reported. For comparison, the earlier reported homoleptic tris-amidinate [In(amd)3] (3) was also synthesized and analyzed in detail especially with respect to the thermal properties and molecular crystal structure analysis which are reported here for the first time. From nuclear magnetic resonance spectroscopy (NMR) and single-crystal X-ray diffraction (XRD), all three compounds were found to be monomeric with C2 (compound 1 and 2) and C3 symmetry (compound 3). Both halide-free compounds 2 and 3 were evaluated regarding their thermal properties using temperature-dependent 1H-NMR, thermogravimetric analysis (TGA) and iso-TGA, revealing suitable volatility and thermal stability for their application as potential precursors for chemical vapor phase thin film deposition methods. Indeed, metalorganic chemical vapor deposition (MOCVD) experiments over a broad temperature range (400 °C-700 °C) revealed the suitability of these two compounds to fabricate In2O3 thin films in the presence of oxygen on Si, thermally grown SiO2 and fused silica substrates. The as-deposited thin films were characterized in terms of their crystallinity via X-ray diffraction (XRD), morphology by scanning electron microscopy (SEM) and composition through complementary techniques such as Rutherford-backscattering spectrometry (RBS) in combination with nuclear reaction analysis (NRA) and X-ray photoelectron spectroscopy (XPS). From UV/Vis spectroscopy, the deposited In2O3 thin films on fused silica substrates were found to be highly transparent (T > 95% at 560 nm, compound 3). In addition, Hall measurements revealed high charge carrier densities of 1.8 × 1020 cm-3 (2) and 6.5 × 1019 cm-3 (3) with a Hall-mobility of 48 cm2 V-1 s-1 (2) and 74 cm2 V-1 s-1 (3) for the respective thin films, rendering the obtained thin films applicable as a transparent conducting oxide that could be suitable for optoelectronic applications.

Fabrication of air-stable, large-area, PCDTBT:PC70BM polymer solar cell modules using a custom built slot-die coater

Polymer solar cell (PSC) manufacturing is strongly influenced by the thin film deposition method with the morphology of the bulk heterojunction (BHJ) coupled intimately to the efficiency of the device. Although ideally scalable deposition methods suitable for sheet-to-sheet (S2S) or roll-to-roll (R2R) production should be used in the investigation of PSCs, research still predominately relies on spin-coating due to ease of use and lower associated costs. Here we present the development and characterization of a lab-scale slot-die coater and demonstrate its use to fabricate air-stable, large-area, solar cell modules. We adapt an entry level paint applicator into a fully-functional S2S slot-die coater and provide its open source documentation to support the research community in availing itself of scalable photovoltaic technologies for device fabrication. The optimization of the process parameters results in homogeneous layers that have been extensively characterized by light beam induced current (LBIC), micro photoluminescence (PL), and micro Raman mapping of whole modules. We report the successful demonstration of the fabrication of PSC modules with an active area above 35cm2 and a power conversion efficiency exceeding 3%. We also investigate the behavior of the module characteristics at different annealing temperatures and its stability during operation under ambient conditions. This work will facilitate research on scaling up of laboratory organic electronic devices and allow more efficient transition from Lab-to-Fab.

Studies on structural, optical and electrical properties of electron beam evaporated Cu2SnSe3 thin films

Abstract The present work describes the deposition of semiconducting Cu2SnSe3 thin films by electron beam evaporation method. The structure of the deposited films was characterized by XRD and Raman analysis. X-ray diffraction study revealed that the Cu2SnSe3 thin films had a cubic sphalerite-like structure with crystallite size of 12 nm. Raman spectrum of the thin films confirmed the phase purity. FESEM analysis showed a continuous film with polydispersed grains of a diameter less than 1 цш and the elemental composition was confirmed by EDS spectrum. The UV-Vis spectrum revealed that the sample had high absorption in the visible region and the band gap was found to be 1.15 eV. The I-V graph exhibited the electrical resistivity and conductivity of the film as 2.13 Ω-cm and 0.468 S/cm, respectively. Thus, the electron beam evaporated Cu2SnSe3 thin films showed high purity of structure and good morphological, optical and electrical properties comparable with other methods of thin film deposition.

Fabrication, Testing, and Simulation of All-Solid-State Three-Dimensional Li-Ion Batteries.

Demonstration of three-dimensional all-solid-state Li-ion batteries (3D SSLIBs) has been a long-standing goal for numerous researchers in the battery community interested in developing high power and high areal energy density storage solutions for a variety of applications. Ideally, the 3D geometry maximizes the volume of active material per unit area, while keeping its thickness small to allow for fast Li diffusion. In this paper, we describe experimental testing and simulation of 3D SSLIBs fabricated using materials and thin-film deposition methods compatible with semiconductor device processing. These 3D SSLIBs consist of Si microcolumns onto which the battery layers are sequentially deposited using physical vapor deposition. The power performance of the 3D SSLIBs lags significantly behind that of similarly prepared planar SSLIBs. Analysis of the experimental results using finite element modeling indicates that the origin of the poor power performance is the structural inhomogeneity of the 3D SSLIB, coupled with low electrolyte ionic conductivity and diffusion rate in the cathode, which lead to highly nonuniform internal current density distribution and poor cathode utilization.

Hybrid Film Deposition for High-Aspect-Ratio Structures with Functional Surfaces

Thin film deposition is one of the most significant issues in the fabrication of nano structures. Especially it is difficult to achieve conformal films on high-aspect ratio nanostructures, such as nanoholes and nanochannels. Though there are various thin film deposition processes, atomic layer deposition (ALD) has attracted due to its extreme surface conformality and excellent thickness controllability. Because ALD is a chemical gas phase thin film deposition method based on sequential and self-saturating surface reactions, it can be used for coating of nano structures with high-aspect ratio. Sputtering process is one of the popular film deposition techniques due to its relative simplicity of process and fast deposition speed. However, film depositions by sputtering technique are less conformal compared to those by ALD, because of ions directionality sputtered by plasma. Therefore it is difficult to form films on the surfaces perpendicular to substrate by sputtering process. However, if ALD and sputtering processes are combined, hybrid thin films deposition which different films are deposited on selectively different surfaces (eg. surfaces perpendicular and parallel to substrate). In this poster, I will present the results of hybrid films deposition on nano holes/channels structures with high-aspect ratio. For different functionalities (hydrophilicity and hydrophobicity) of surfaces, Al2O3 and Pt films were grown on nanochannel structures. Al2O3 films deposition on the vertical surfaces (inner surfaces of nanochannels) was controlled precisely in nanometer scale by using ALD process. Pt films were formed on horizontal surfaces (outer surfaces of nanochannels) by using DC magnetron sputtering.

Inkjet-Printed Oxide TFTs with Solution-Processed Dual Semiconductors

The solution process is a simple and low-cost thin film deposition method that enables a large area coating and high throughput because it can circumvent the need for photolithography and vacuum deposition. Direct patterning can be processed with screen printing, imprinting, ink-jet printing, and electrohydrodynamic-jet printing. Among them, inkjet printing is an attractive technique in device fabrication for the direct pattern writing and precise materials delivery. Recently, spin-coated double-active layer oxide TFTs, in which heterostructured channels, were reported to obtain improved electrical properties at relatively low processing temperatures. However, inkjet printing can provide a patterned active layer structure and give better properties compared to a simple spin-coated one. To achieve the optimized electrical properties of an inkjet-printed double-active layer, the ZTO TFTs with various compositions of In2O3 solutions were examined. By controlling the annealing temperature and indium content, heterostructured In2O3/ZTO TFTs with improved mobility, threshold voltage and bias stability were obtained. The best electrical properties of the inkjet-printed double-active layer ZTO TFTs were obtained with 0.01 M of In2O3: a mobility of 8.6 cm2/ V s, a threshold voltage of 2.76 V, a subthreshold slope of 0.52 V/dec, and an on-to-off current ratio of 106 . The electrical properties of the inkjet-printed double-active layer oxide TFTs were superior to those of the single-active layered TFTs.

High-Aspect-Ratio Ridge Structures Induced by Plastic Deformation as a Novel Microfabrication Technique.

Wrinkles on thin film/elastomer bilayer systems provide functional surfaces. The aspect ratio of these wrinkles is critical to their functionality. Much effort has been dedicated to creating high-aspect-ratio structures on the surface of bilayer systems. A highly prestretched elastomer attached to a thin film has recently been shown to form a high-aspect-ratio structure, called a ridge structure, due to a large strain induced in the elastomer. However, the prestretch requirements of the elastomer during thin film attachment are not compatible with conventional thin film deposition methods, such as spin coating, dip coating, and chemical vapor deposition (CVD). Thus, the fabrication method is complex, and ridge structure formation is limited to planar surfaces. This paper presents a new and simple method for constructing ridge structures on a nonplanar surface using a plastic thin film/elastomer bilayer system. A plastic thin film is attached to a stress-free elastomer, and the resulting bilayer system is highly stretched one- or two-dimensionally. Upon the release of the stretch load, the deformation of the elastomer is reversible, while the plastically deformed thin film stays elongated. The combination of the length mismatch and the large strain induced in the elastomer generates ridge structures. The morphology of the plastic thin film/elastomer bilayer system is experimentally studied by varying the physical parameters, and the functionality and the applicability to a nonplanar surface are demonstrated. Finally, we simulate the effect of plasticity on morphology. This study presents a new technique for generating microscale high-aspect-ratio structures and its potential for functional surfaces.

Effect of Gd-doped ceria interlayer on the stability of solid oxide electrolysis cell

Gd0.2Ce0.8O2-δ (GDC) interlayers, positioned between La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) anode (air electrode) and yttria-stabilized zirconia (Y0.16Zr0.84O2-d, YSZ) electrolyte of solid oxide electrolysis cells (SOECs) to prevent mutual reaction, are compared that used either thin-film deposition method to produce dense layers or screen-printing to produce porous layers. Two cells with 2μm-thick GDC layers are sputter deposited, one annealed at 1300°C and the other at 1100°C. During SOEC operation with an anodic current density of −800mAcm−2 in 80% H2O+20% H2 at 800°C, the two cells show similar Ohmic and polarization resistances at the beginning of measurement, but the cell annealed at 1300°C is more stable after 100h than the film annealed at 1100°C due to the stability of pinhole free nature of GDC layer. In a third cell with ~11μm-thick screen-printed GDC layer, GDC is porous and therefore the cell degrades more rapidly during SOEC operation for 100h than does a cell with ~2μm-thick, pin-hole free GDC film. The good stability of the cell with dense, pin-hole free GDC thin film is attributed to its blocking of Sr.

Atomic Layer Deposition of Iridium Thin Films Using Sequential Oxygen and Hydrogen Pulses

Atomic layer deposition (ALD) is an advanced thin-film deposition method based on self-limiting surface reactions that allows for the controlled deposition of conformal, high-quality thin films of various materials. In this study, we aimed to explore how modifying the deposition chemistry affects the growth and properties of iridium films. We demonstrated a new ALD process using sequential pulses of iridium acetylacetonate [Ir(acac)3], oxygen (O2), and hydrogen (H2) and compared this to the established Ir(acac)3 + O2 process in the wide temperature range of 200–350 °C. A reaction scheme is proposed to explain how both oxygen and hydrogen affect the film growth. Comprehensive information on film properties was obtained for both processes. In particular, the strong (111) texture seen in this study has not been reported before for ALD iridium films. Changes in film properties, especially lowered resistivity, stronger (111) texture, and faster nucleation compared to the Ir(acac)3 + O2 process, should motivate...

Thin Films of Organic Electrode Materials for All-Solid-State 3D-Microbattery Applications

The miniaturization of electronic devices demands for energy storage systems of equal size. As the conventional liquid electrolyte cells do not scale well enough, the current focus is on all-solid-state thin film batteries. In order to increase the energy density while preserving the power density of the cells, nanostructuring of the substrate to increase the effective surface area is seen as a viable option. Such an approach places an apparent need for a thin-film deposition method capable of manufacturing the electrode and electrolyte materials on high aspect ratio substrates. A strong candidate for the task is the atomic layer deposition (ALD) technique which is based on sequential surface reactions of gaseous precursors. The surface saturation limited growth results in excellent conformality over complex surface features. However, the availability of ALD processes for Li-ion battery materials is severely lacking. By utilizing combined atomic/molecular layer deposition (ALD/MLD) technique, we broaden the range of available electrode materials to those based on conjugated carbonyl systems. These organic electrode materials combine the high gravimetric energy density with abundant and environmentally benign constituents. We present demonstrative ALD/MLD processes for both anode and cathode materials and verify the electrochemical activity of the as-deposited thin films. Also shown is that the nanoscaling of the materials can be utilized to overcome the inherently poor kinetics of organic electrode materials without relying on any conductive additives. As the ALD/MLD method allows for making the cathode material directly in the fully-lithiated reduced state, the as-deposited pair can be combined into a full cell without an additional lithiation step.

Thin film synthesis of SbSI micro-crystals for self-powered photodetectors with rapid time response.

We describe a new thin film deposition method for the growth of crystalline SbSI micro-needles via the conversion of Sb2S3 using SbI3 vapour, in a facile process that takes less than 15 minutes. These films were used to construct photodetectors in a sandwich-type architecture, which are superior to previously reported SbSI photodetectors. The devices exhibit a detectivity of D* = 10(9) Jones, a signal-to-noise ratio greater than SNR = 10(3) and a responsivity of R = 10(-5) A W(-1). In time response measurements, raise and fall times of less than 8 ms and 34 ms were determined. This manufacturing method greatly simplifies the creation of fast photodetectors.

Water oxidation catalysis: an amorphous quaternary Ba-Sr-Co-Fe oxide as a promising electrocatalyst for the oxygen-evolution reaction

We present an amorphous quaternary Ba-Sr-Co-Fe oxide (a-BSCF) with a specific stoichiometry, readily fabricated via a photochemical decomposition method. a-BSCF demonstrates high catalytic activity towards the oxygen-evolution reaction (OER).

Heavily carbon doped GaAs nanocrystalline thin film deposited by thermionic vacuum arc method

In this paper, we introduced a new different thin film deposition method for heavily carbon doped GaAs. Used method is thermionic vacuum arc (TVA) and first used for the carbon doping process. The method is very fast deposition process for the other growth method such as metal organic chemical vapor deposition, molecular beam epitaxy, molecular organic molecular beam epitaxy. The smallest grain size of GaAs and doped GaAs were obtained by carbon doping process. Mean crystalline size and height of crystalline size were found to be 3.4 nm and 4 nm, respectively. Crystal direction was found to be (022) plane and (024) plane for the sample at 45.322° and 75.060°, respectively. The production process and obtained results show that used methods is very simple, low cost, eco friendly and very fast method for the carbon doped GaAs.

(Invited) Opportunities in Atomic Layer Deposition for Electronic Textile and Hydrophobic Coating Applications

Atomic layer deposition (ALD) has been widely applied for high technology applications from semiconductor industry to energy devices since it has several superior properties in nanoscale device fabrications, such as excellent conformality, large area uniformity, and process compatibility, over the conventional thin film deposition methods. In this work, we extended ALD researches to two novel applications, electronic textile (e-textile) and hydrophobic coating applications. We developed a Pt ALD process capable of low temperature deposition down to 80 °C using a new Pt precursor and O2 counter reactant. Pt was deposited on organic textile substrates, such as cotton and Nylon. The ALD-Pt-coated textiles showed high electrical conductivity and high mechanical durability even after mechanical wrinkling test. Fabrications of pressure sensor arrays using ALD-Pt-coated textile were demonstrated. For the hydrophobic coating, we developed rear earth oxides (REOs) ALD including Y2O3, La2O3, CeO2, Dy2O3 and Er2O3 by using new rare earth precursors All the ALD REOs showed hydrophobic property over 100 ° of water contact angles. In addition, the hydrophobicity of ALD REOs showed high durability even after high temperature process over 500 °C. A superhydrophobic surface was fabricated by using ALD REOs and nanostructured Si surface. The nanostructured Si coated by ALD REOs showed very high water contact angle as high as 158 °.

The Challenge of 3D All Solid State Li-Ion Battery

Demonstration of all-solid state 3-dimensional (3D) Li-ion batteries has been a long standing goal for numerous researchers in the battery community interested in developing high power and high areal energy density storage solutions for variety of applications. The basic idea is to use the 3D geometry to maximize the volume of active material per unit area, while keeping its thickness sufficiently small to allow for fast Li diffusion. The 3D approach also leads to high electrode/electrolyte interface area, which should prove beneficial by lowering the local current density and therefore the charge transfer resistance, assuming that the interface is stable against parasitic reactions and breakdown. While simple conceptually, realizing working all solid state Li ion batteries has proven to be a significant challenge. Specifically, the physical vapor deposition processes which have been successfully implemented for planar, thin film solid state Li ion batteries, fail miserably when applied to 3D substrates, particularly with high aspect ratio features. In our presentation, we will describe the structure and performance of all solid state 3D Li ion batteries fabricated by physical vapor deposition. Although these can be charged and discharged at low C-rates, their capacity decreases rapidly at higher C-rates. In our presentation we will discuss the underlying reasons for the poor performance and demonstrate how these problems can be addressed using atomic layer deposition, a thin film deposition method compatible with high aspect ratio geometries. Figure 1

Hybrid Films Deposition for Nanochannel Membranes with Functional Surfaces

Thin film deposition is one of the most significant issues in the fabrication of nano structures. Especially it is difficult to achieve conformal films on high-aspect ratio nanostructures, such as nanochannel membranes. Though there are various thin film deposition techniques, atomic layer deposition (ALD) has attracted due to its extreme surface conformality and excellent thickness controllability. Because ALD is a chemical gas phase thin film deposition method based on sequential and self-saturating surface reactions, it can be used for coating of nano structures with high-aspect ratio. Sputtering process is one of the popular film deposition techniques due to its relative simplicity of process and fast deposition speed. However, film depositions by sputtering technique are less conformal compared to those by ALD, because of ions directionality sputtered by plasma. Therefore it is difficult to form films on the surfaces perpendicular to substrate by sputtering process. However, if ALD and sputtering techniques are combined, hybrid thin films deposition which different films are deposited on selectively different surfaces (eg. surfaces perpendicular and parallel to substrate). In this poster, I will present the results of hybrid films deposition on nanochannel membranes with high-aspect ratio. For different functionalities (hydrophilicity and hydrophobicity) of surfaces, Al2O3 and Pt films were grown on nanochannel membranes. Al2O3 films deposition on the vertical surfaces (inner surfaces of nanochannels) was controlled precisely in nanometer scale by using ALD process. Pt films were formed on horizontal surfaces (outer surfaces of nanochannels) by using DC magnetron sputtering. In addition, I will also present the ionic seperation in NaCl solution using fabricated nanochannel membranes by hybrid deposition process and using electrcal bias on Pt films.

Atomic Layer Deposition and Anodic Oxidation: A Good Tool Combination to Build Nanostructured Electrodes for Energy Applications

Anodic oxidation has been used for a longtime as a way to passivate metallic electrodes to prevent corrosion. It is the discovery of self-ordered nanoporous alumina membranes reported in 1995 [1] that has revealed its potential use for surface nanostructuring. Later, the anodic growth of TiO2 nanotubes (TiO2-nt) has considerably widened the field of applications of such approach since TiO2 exhibits many valuable properties [2]. It is now possible to use other metals or alloys to grow porous or tubular oxidized nanostructures. However to further improve the properties of such electrodes, it is necessary to functionalize their surface with other materials of interest. Among the various thin film deposition methods, Electrochemical Deposition (ED) and Atomic Layer Deposition (ALD) have shown a great ability to conformally coat porous structures exhibiting a high aspect ratio. The main advantages of ALD over ED is that it can be carried out onto non-conductive materials, it allows an accurate control of the thickness and it is usually more direct to grow oxides or nitrides. We report, here, three examples of nanostructured electrodes fabricated using anodic oxidation of Al and Ti in combination with ALD of active materials. The targeted applications are in the fields of electrocatalysis, Li-ion microbatteries and photoelectrochemical water splitting. Direct Ethanol Fuel Cells offer significant advantages due to ethanol non-toxicity and renewability and its high power density. TiO2 have been successfully used as replacement of C as catalyst support because it exhibits a good chemical stability and it can enhance the activity of the catalyst. After a brief reminding on the TiO2-nt fabrication and properties, the ALD of Pd nanoparticles into TiO2-nt array will be presented. The electrochemical activity toward ethanol oxidation has been tested in alkaline medium. Although a high and stable electroactivity has been measured further improvements such as annealing of the TiO2-nt and ALD of SnO2 onto the TiO2-nt have been proposed. As seen on Fig. 1a, the electrochemical response is at its highest when the tubes have been annealed and covered by SnO2. A 3D nano-architectured composite negative electrode has been fabricated in order to be used in microbatterie. It consists of TiO2-nt coated by a thin SnO2 film grown by ALD. TiO2-nt are known to exhibits very good insertion properties and the SnO2 coating that displays a high lithium insertion capability (max. theoretical capacity of 720 µAh/cm2·µm) is used to enlarge the capacity of the electrode. Such composite 3D structure increases therefore the active area, improves the kinetics of the system, facilitates the ion exchange at the electrode/electrolyte interface and, better accommodates the volume expansion induced by the Li insertion within the LixSn alloy. The ALD of SnO2 will be described in details. The influence of various parameters such as precursor nature, exposure sequence as well as reaction temperature on the deposit morphology, chemistry and crystalline structure will be presented. The electrochemical performances of such systems have been tested as function of the SnO2 film thickness and after thermal treatments that change the crystalline structure of the electrodes. The results show that TiO2/SnO2 delivers a promising capacity (~150 µAh/cm2) which is better than bare TiO2-nt (Fig. 1b). It demonstrated then that such 3D nano-architectured composite electrode opens valuable perspectives for microbatteries design. The last example consists of producing a nanostructured photocathode for water splitting in which the photogeneration and transport of the charge carriers do not occur in the same material. In order to create tailored 3D nanostructures, p-NiO and i-Sb2S3 thin films have been successively grown into nanoporous alumina by ALD (Fig. 1c). The photocathode composition, structure and geometry are well controlled. Then the optical and photoelectrochemical properties have been investigated and optimized using cyclic voltammetry in the dark and under illumination as well as UV-visible absorption spectroscopy. It has been sought to uncover trends in the photoelectrochemical activity of the system (photocurrent density and photovoltage) and rationalize them in terms of optical and electrical functions. [1] H. Masuda, K. Fukuda, Science, 268, 1466 (1995) [2] V. Zwilling, E. Darque-Ceretti, A. Boutry-Forveille, D. David, M. Y. Perrin, M. Aucouturier, Surf. Interface Anal., 27, 629 (1999) Figure 1

Characteristics and mechanism study of cerium oxide based random access memories

In this work, low operating voltage and high resistance ratio of different resistance states of binary transition metal oxide based resistive random access memories (RRAMs) are demonstrated. Binary transition metal oxides with high dielectric constant have been explored for RRAM application for years. However, CeOx is considered as a relatively new material to other dielectrics. Since research on CeOx based RRAM is still at preliminary stage, fundamental characteristics of RRAM such as scalability and mechanism studies need to be done before moving further. Here, we show very high operation window and low switching voltage of CeOx RRAMs and also compare electrical performance of Al/CeOx/Au system between different thin film deposition methods and discuss characteristics and resistive switching mechanism.