Search results for "Phase Transition"
showing 10 items of 1281 documents
Pulsed Direct liquid Injection ALD of TiO2 Films Using Titanium Tetraisopropoxide Precursor
2013
Abstract TiO 2 thin films are grown by pulsed direct liquid injection atomic layer deposition with rapid thermal heating using titanium tetraisopropoxide and water vapor as precursors. The ALD growth rate is constant in the saturation zone range 35-47 ms at the temperature deposition of 280 °C. The TiO 2 growth rate of 0.018 nm/cycle was achieved in a self-limited ALD mode. SEM and AFM analysis showed the as-deposited films have a smooth surface with a low roughness. XPS analysis exhibited the stoichiometry of TiO 2 in the homogenous depth composition.
WS2 2D Semiconductor Down to Monolayers by Pulsed-Laser Deposition for Large-Scale Integration in Electronics and Spintronics Circuits
2020
International audience; We report on the achievement of a large-scale tungsten disulfide (WS2) 2D semiconducting platform derived by pulsed-laser deposition (PLD) on both insulating substrates (SrTiO3), as required for in-plane semiconductor circuit definition, and ferromagnetic spin sources (Ni), as required for spintronics applications. We show thickness and phase control, with highly homogeneous wafer-scale monolayers observed under certain conditions, as demonstrated by X-ray photoelectron spectroscopy and Raman spectroscopy mappings. Interestingly, growth appears to be dependent on the substrate selection, with a dramatically increased growth rate on Ni substrates. We show that this 2D…
Deposition Kinetics and Compositional Control of Vacuum-Processed CH3NH3PbI3 Perovskite
2020
Halide perovskites have generated considerable research interest due to their excellent optoelectronic properties in the past decade. To ensure the formation of high-quality semiconductors, the deposition process for the perovskite film is a critical issue. Vacuum-based processing is considered to be a promising method, allowing, in principle, for uniform deposition on a large area. One of the benefits of vacuum processing is the control over the film composition through the use of quartz crystal microbalances (QCMs) that monitor the rates of the components in situ. In metal halide perovskites, however, one frequently employed component or precursor, CH3NH3I, exhibits nonstandard sublimatio…
Physical vapor deposition of Bi2S3 as absorber material in thin film photovoltaics
2013
Abstract In order to investigate alternative absorber materials for inorganic solar cells, thin films of bismuth trisulfide (Bi2S3) were deposited under high vacuum conditions by the thermal evaporation method from compound material. The effects of the substrate temperature during deposition on the structural, stoichiometric, optical and electrical properties were investigated. Polycrystalline thin films close to an ideal stoichiometry could be deposited for temperatures TSub = 80–290 °C; thereby a transition from rough needle-shaped particles with (hk0)-orientation parallel to the surface of the substrate towards block shaped grains with a preferred direction out of the surface could be ob…
Photovoltaic devices employing vacuum-deposited perovskite layers
2015
Organic–inorganic perovskites have emerged as one of the most promising materials for future optoelectronics applications, most notably photovoltaics. The achievement of high-efficiency solar cells has been possible mainly through the understanding of the perovskite formation during the solution deposition of thin films. Vacuum deposition methods have also been developed and have intrinsic advantages over solution-based processing, including control over the film thickness and composition, low-temperature processing, and the possibility of preparing multilayer structures. This article summarizes the latest advances in the vacuum deposition of hybrid perovskites, with an emphasis on the appl…
An epitaxial hexagonal tungsten bronze as precursor for WO3 nanorods on mica.
2008
International audience; Tungsten oxide nanorods are grown at atmospheric pressure and low temperature (360 1C), by sublimation of WO3 and condensation on mica substrates. The nanorods are characterized by atomic force microscopy, high-resolution electron microscopy, energy-dispersive X-ray spectroscopy and high energy electron diffraction. The experimental results evidence the formation of a hexagonal tungsten bronze at the nanorod–substrate interface. The epitaxial relationships of the nanorods on mica are determined and the role of epitaxial orientation of the interfacial bronze in the nanorod growth and morphology are discussed.
Stabilization of MCM-41 by Pyrolytic Carbon Deposition
2000
A new method of surface modification which is effective in stabilizing silica grades of MCM-41 in the presence of water vapor is presented. It is shown by means of XRD, low-temperature nitrogen ads...
Enamine-based hole transporting materials for vacuum-deposited perovskite solar cells
2020
In a short period of time, the rapid development of perovskite solar cells attracted a lot of attention in the science community with the record for power conversion efficiency being broken every year. Despite the fast progress in power conversion efficiency there are still many issues that need to be solved before starting large scale commercial applications, such as, among others, the difficult and costly synthesis and usage of toxic solvents for the deposition of hole transport materials (HTMs). We herein report new enamine-based charge transport materials obtained via a simple one step synthesis procedure, from commercially available precursors and without the use of expensive organomet…
Morphological and Chemical Evolution of Gradually Deposited Diamond-Like Carbon Films on Polyethylene Terephthalate: From Subplantation Processes to …
2016
Diamond-like carbon (DLC) films on polyethylene terephthalate (PET) are nowadays intensively studied composites due to their excellent gas barrier properties and biocompatibility. Despite their applicative features being highly explored, the interface properties and structural film evolution of DLC coatings on PET during deposition processes are still sparsely investigated. In this study two different types of DLC films were gradually deposited on PET by radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) using acetylene plasma. The surface morphology of the deposited samples has been analyzed by atomic force microscopy (AFM). Their chemical composition was investigated by …
Methods for Enhancing the Thermal Durability of High-Temperature Thermoelectric Materials
2013
Author's version of an article in the journal: Journal of Electronic Materials. Also available from the publisher at: http://dx.doi.org/10.1007/s11664-013-2917-0 Thermoelectric materials, for example skutterudites and magnesium silicides, are being investigated as promising materials for medium-to-high-temperature waste heat recovery in transport and in industry. A crucial aspect of the success of a thermoelectric material is its stability over time when exposed to rapid heating and cooling. In this work different aspects of the degradation of these thermoelectric materials at high temperature were examined. Initial thermal durability was studied, and several candidate coatings were evaluat…