scholarly journals TSF-MOCVD – a novel technique for chemical vapour deposition on oxide thin films and layered heterostructures

2021 ◽  
Vol 23 (3) ◽  
pp. 396-405
Author(s):  
Andrey R. Kaul ◽  
Roy R. Nygaard ◽  
Vadim Yu. Ratovskiy ◽  
Alexander L. Vasiliev
Keyword(s):  
Film Growth ◽  
Chemical Vapour ◽  
Chemical Deposition ◽  
Deposition Process ◽  
Epitaxial Films ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Transmission Microscopy ◽  
Integral Width ◽  
Volatile Precursors

A new principle for supplying volatile precursors to MOCVD gas-phase chemical deposition systems is proposed, based on a two-stage evaporation of an organic solution of precursors from a soaked cotton thread, which passes sequentially through the zones of evaporation of the solvent and precursors. The technological capabilities of TSF-MOCVD (Thread-Solution Feed MOCVD) are demonstrated based on examples of obtaining thin epitaxial films of СеО2, h-LuFeO3 and thin-film heterostructures β-Fe2O3/h-LuFeO3. The results of studying the obtained films by X-ray diffraction, energy dispersive X-rayanalysis, and high- and low-resolution transmission microscopy are presented. Using the TSF module, one can finely vary the crystallisation conditions, obtaining coatings of the required degree of crystallinity, as  evidenced by the obtained dependences of the integral width of the h-LuFeO3 reflection on the film growth rate. Based on the TEM and XRD data, it was concluded that β-Fe2O3 grows epitaxially over the h-LuFeO3 layer. Thus, using TSF-MOCVD, one can flexibly change the composition of layered heterostructures and obtain highly crystalline epitaxial films with a clear interface in a continuous deposition process

scholarly journals Gas-sensing behaviour of ZnO/diamond nanostructures

2018 ◽  
Vol 9 ◽  
pp. 22-29 ◽  
Author(s):  
Marina Davydova ◽  
Alexandr Laposa ◽  
Jiri Smarhak ◽  
Alexander Kromka ◽  
Neda Neykova ◽  
...  
Keyword(s):  
Microwave Plasma ◽  
Gas Sensing ◽  
Zno Nanorods ◽  
Chemical Vapour ◽  
Deposition Process ◽  
Hybrid Structure ◽  
X Ray Diffraction ◽  
Gas Sensing Properties ◽  
P Type ◽  
Synthesized Materials

Microstructured single- and double-layered sensor devices based on p-type hydrogen-terminated nanocrystalline diamond (NCD) films and/or n-type ZnO nanorods (NRs) have been obtained via a facile microwave-plasma-enhanced chemical vapour deposition process or a hydrothermal growth procedure. The morphology and crystal structure of the synthesized materials was analysed with scanning electron microscopy, X-ray diffraction measurements and Raman spectroscopy. The gas sensing properties of the sensors based on i) NCD films, ii) ZnO nanorods, and iii) hybrid ZnO NRs/NCD structures were evaluated with respect to oxidizing (i.e., NO2, CO2) and reducing (i.e., NH3) gases at 150 °C. The hybrid ZnO NRs/NCD sensor showed a remarkably enhanced NO2 response compared to the ZnO NRs sensor. Further, inspired by this special hybrid structure, the simulation of interaction between the gas molecules (NO2 and CO2) and hybrid ZnO NRs/NCD sensor was studied using DFT calculations.

InN on GaN Heterostructure Growth by Migration Enhanced Epitaxial Afterglow (MEAglow)

2012 ◽  
Vol 1396 ◽  
Author(s):  
Peter W. Binsted ◽  
Kenneth Scott A. Butcher ◽  
Dimiter Alexandrov ◽  
Penka Terziyska ◽  
Dimka Georgieva ◽  
...  
Keyword(s):  
Vapour Deposition ◽  
Film Growth ◽  
Chemical Vapour ◽  
Xrd Analysis ◽  
Alloy Layer ◽  
Third Party ◽  
X Ray Diffraction ◽  
Hall Effect Measurements ◽  
Ingan Alloy ◽  
Gan Heterostructure

ABSTRACTIn this paper we discuss the formation of InN on GaN heterostructures. Film growth was accomplished using a new method coined Migration Enhanced Epitaxial Afterglow (MEAglow), an improved form of pulsed delivery Plasma Enhanced Chemical Vapour Deposition (PECVD) [1]. Initial x-ray diffraction (XRD) analysis results indicated that an InGaN alloy layer formed under the InN during growth. No GaN was seen from the original buffer layer. It was postulated that indium metal deposited prior to complete nitridation diffused into the relatively thin GaN layer producing InGaN. To verify the integrity of the insulating GaN layer, a third party GaN substrate was substituted. Results were unchanged. Parameters were then modified to reduce the amount of indium used for the initial metal deposition. XRD results indicated a sharper interface between the semi-insulating GaN and conductive InN layer. Hall Effect measurements are included. We’ve shown that the growth of a device suitable heterostructure is possible using the MEAglow technique.

Characterization of Epitaxial Films by Grazing-Incidence X-Ray Diffraction

1986 ◽  
Vol 77 ◽  
Author(s):  
Armin Segmüller
Keyword(s):  
Film Growth ◽  
Grazing Incidence ◽  
Misfit Strain ◽  
Epitaxial Films ◽  
X Ray Diffraction ◽  
Diffraction Intensity ◽  
X Ray ◽  
Growth Plane ◽  
Structural Details

ABSTRACTGrazing-incidence x-ray diffraction, a surface-sensitive technique, has been used to obtain structural details parallel to the interface of an epitaxial system, such as lattice parameters, strain, crystallite size and orientation, on films with thicknesses ranging down to a few mono-atomic layers. Tungsten grows epitaxially on the (1102) plane of sapphire, with the orientation W (001) ∥ Al2O3 (1102) and W [110] ∥ Al2O, [1120]. Sufficient diffraction intensity for characterization could be obtained from ∼30A-thick W films. Layers of GaAs can be grown epitaxially on the basal plane of sapphire with the orientation GaAs(111) ∥ Al2O3(00.1) and GaAs [110] ∥ Al2O3[1120]. Niobium films grow on GaAs (001) and (111) substrates with a (001) plane parallel to the interface, whereas molybdenum films prefer to grow with a (111) plane on both substrates. The best orientation, i. e. the smallest mosaic spread, of the film is obtained when the substrate plane has the same symmetry as the preferred film growth plane. In all these cases with relatively large misfit, the strain observed parallel to the interface is only a small fraction of the theoretical misfit strain, indicating the relief of the misfit strain within the first few atomic layers.

Structural Control of Epitaxially Grown Sputtered Perovskite Thin Films

1995 ◽  
Vol 401 ◽  
Author(s):  
Kiyotaka Wasa ◽  
Toshifumi Sato ◽  
Hideaki Adachi ◽  
Kentaro Setsune ◽  
S. Trolier-McKinstry ◽  
...  
Keyword(s):  
Thin Films ◽  
Single Crystal ◽  
Structural Control ◽  
Film Growth ◽  
Substrate Surface ◽  
Epitaxial Films ◽  
Crystal Phase ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Atomic Force

AbstractThin films of perovskite Pb–Ti–O3 families were heteroepitaxially grown by sputtering on (0001)sapphire and/or (001)SrTiO (ST). These epitaxial films contained microstructures, although X–ray diffraction analysis suggested formation of single crystal phase with three dimentional crystal orientation. Their microstructures were studied by the electron microscopy, atomic force microscopy, and spectroscopic ellipsometry so as to find factors which influence the formation of the microstructure. It was found that the orientation of the substrate surface and the chemical composition of adatoms during initial film growth strongly affected the formation of the microstructures. Sputtered PbTiO3 (PT) thin films under a stoichiometric condition on a miscut(001) ST(miscut 1.7 degree) realized the growth of continuous single crystal thin films of 10–100nm thick with extremely smooth surface with surface roughness less than 3nm. Deposition on a miscut substrate under a stoichiometric condition is essential to make continuous thin films of perovskite of single crystal phase.

scholarly journals Polyurethane Composite Foams Synthesized Using Bio-Polyols and Cellulose Filler

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3474
Author(s):  
Katarzyna Uram ◽  
Milena Leszczyńska ◽  
Aleksander Prociak ◽  
Anna Czajka ◽  
Michał Gloc ◽  
...  
Keyword(s):  
Cross Sections ◽  
Raw Materials ◽  
Polyurethane Foams ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Polyurethane Composite ◽  
Composite Foams ◽  
Closed Cell ◽  
Ft Ir ◽  
The Fourier Transform

Rigid polyurethane foams were obtained using two types of renewable raw materials: bio-polyols and a cellulose filler (ARBOCEL® P 4000 X, JRS Rettenmaier, Rosenberg, Germany). A polyurethane system containing 40 wt.% of rapeseed oil-based polyols was modified with the cellulose filler in amounts of 1, 2, and 3 php (per hundred polyols). The cellulose was incorporated into the polyol premix as filler dispersion in a petrochemical polyol made using calenders. The cellulose filler was examined in terms of the degree of crystallinity using the powder X-ray diffraction PXRD -and the presence of bonds by means of the fourier transform infrared spectroscopy FT-IR. It was found that the addition of the cellulose filler increased the number of cells in the foams in both cross-sections—parallel and perpendicular to the direction of the foam growth—while reducing the sizes of those cells. Additionally, the foams had closed cell contents of more than 90% and initial thermal conductivity coefficients of 24.8 mW/m∙K. The insulation materials were dimensionally stable, especially at temperatures close to 0 °C, which qualifies them for use as insulation at low temperatures.

scholarly journals A novel and potentially scalable CVD-based route towards SnO2:Mo thin films as transparent conducting oxides

2021 ◽  
Author(s):  
Tianlei Ma ◽  
Marek Nikiel ◽  
Andrew G. Thomas ◽  
Mohamed Missous ◽  
David J. Lewis
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Mixed Valence ◽  
Chemical Vapour ◽  
X Ray Diffraction ◽  
X Ray ◽  
Conducting Oxides ◽  
Valence States ◽  
3 Omega ◽  
First Time

AbstractIn this report, we prepared transparent and conducting undoped and molybdenum-doped tin oxide (Mo–SnO2) thin films by aerosol-assisted chemical vapour deposition (AACVD). The relationship between the precursor concentration in the feed and in the resulting films was studied by energy-dispersive X-ray spectroscopy, suggesting that the efficiency of doping is quantitative and that this method could potentially impart exquisite control over dopant levels. All SnO2 films were in tetragonal structure as confirmed by powder X-ray diffraction measurements. X-ray photoelectron spectroscopy characterisation indicated for the first time that Mo ions were in mixed valence states of Mo(VI) and Mo(V) on the surface. Incorporation of Mo6+ resulted in the lowest resistivity of $$7.3 \times 10^{{ - 3}} \Omega \,{\text{cm}}$$ 7.3 × 10 - 3 Ω cm , compared to pure SnO2 films with resistivities of $$4.3\left( 0 \right) \times 10^{{ - 2}} \Omega \,{\text{cm}}$$ 4.3 0 × 10 - 2 Ω cm . Meanwhile, a high transmittance of 83% in the visible light range was also acquired. This work presents a comprehensive investigation into impact of Mo doping on SnO2 films synthesised by AACVD for the first time and establishes the potential for scalable deposition of SnO2:Mo thin films in TCO manufacturing. Graphical abstract

scholarly journals Chemical and Structural Characterization of Maize Stover Fractions in Aspect of Its Possible Applications

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1527
Author(s):  
Magdalena Woźniak ◽  
Izabela Ratajczak ◽  
Dawid Wojcieszak ◽  
Agnieszka Waśkiewicz ◽  
Kinga Szentner ◽  
...  
Keyword(s):  
Structural Characterization ◽  
Biogas Production ◽  
Structural Parameters ◽  
C:N Ratio ◽  
Crystallinity Index ◽  
Degree Of Crystallinity ◽  
Cellulose Content ◽  
X Ray Diffraction ◽  
Maize Stover

In the last decade, an increasingly common method of maize stover management is to use it for energy generation, including anaerobic digestion for biogas production. Therefore, the aim of this study was to provide a chemical and structural characterization of maize stover fractions and, based on these parameters, to evaluate the potential application of these fractions, including forbiogas production. In the study, maize stover fractions, including cobs, husks, leaves and stalks, were used. The biomass samples were characterized by infrared spectroscopy (FTIR), X-ray diffraction and analysis of elemental composition. Among all maize stover fractions, stalks showed the highest C:N ratio, degree of crystallinity and cellulose and lignin contents. The high crystallinity index of stalks (38%) is associated with their high cellulose content (44.87%). FTIR analysis showed that the spectrum of maize stalks is characterized by the highest intensity of bands at 1512 cm−1 and 1384 cm−1, which are the characteristic bands of lignin and cellulose. Obtained results indicate that the maize stover fraction has an influence on the chemical and structural parameters. Moreover, presented results indicate that stalks are characterized by the most favorable chemical parameters for biogas production.

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