Search results for "Nitride"
showing 10 items of 249 documents
Normal Metal-Insulator-Superconductor Tunnel Junctions With Pulsed Laser Deposited Titanium Nitride as Superconductor
2021
Here we report the fabrication of normal metal – insulator – superconductor (NIS) tunnel junctions using superconducting titanium nitride grown by pulsed laser deposition (PLD). The films for NIS junction fabrication were deposited on two different substrates: silicon nitride film and magnesium oxide. TiN films were characterized by means of electrical transport measurements, and films with superconducting transition temperatures above the liquid helium boiling point were chosen for fabrication of NIS junctions. Tunnel junction devices were successfully fabricated using electron beam lithography and shadow evaporation techniques. The insulator layer formation was performed using two differe…
Polycyclic aromatic chains on metals and insulating layers by repetitive [3+2] cycloadditions
2020
The vast potential of organic materials for electronic, optoelectronic and spintronic devices entails substantial interest in the fabrication of π-conjugated systems with tailored functionality directly at insulating interfaces. On-surface fabrication of such materials on non-metal surfaces remains to be demonstrated with high yield and selectivity. Here we present the synthesis of polyaromatic chains on metallic substrates, insulating layers, and in the solid state. Scanning probe microscopy shows the formation of azaullazine repeating units on Au(111), Ag(111), and h-BN/Cu(111), stemming from intermolecular homo-coupling via cycloaddition reactions of CN-substituted polycyclic aromatic az…
Effects of the Buffer Layers on the Performances of (Al,Ga)N Ultraviolet Photodetectors
2004
The fabrication of (Al,Ga)N-based metal–semiconductor–metal (MSM) photovoltaic detectors requires the growth of high-quality (Al,Ga)N films. Inserting a low-temperature deposited buffer layer enables the growth of an epitaxial layer with a reduced density of defects. Two structures using GaN and AlN buffer layers have been deposited by low-pressure metalorganic chemical vapor deposition and used to fabricate MSM interdigitated detectors. The devices have been characterized to investigate the effects of the buffer layers on the detector performances.
Well-aligned hydrothermally synthesized zinc oxide nanorods on p-GaN without a seed layer
2015
Zinc oxide nanorods have great potential for the realization of high efficiency heterostructure LEDs based on pdoped gallium nitride. In order to obtain a good confinement of the light, a well-aligned nanorod waveguiding structure is desirable. This paper reports on the fabrication of vertical zinc oxide nanorods using a solution-based growth process that does not require a seed layer. The nanorods obtained follow the crystalline growth direction of the GaN layer along the c-axis. Various results with different reagent concentrations are reported.
Curvature radius measurement by optical profiler and determination of the residual stress in thin films
2019
Abstract The Stoney formula, based on the measurement of the substrate curvature, is often used for the determination of the thin films' residual stress. In this study, titanium nitride coatings were deposited by DC reactive magnetron sputtering on silicon substrates. An optical profiler was used to determine the curvature of the surface before and after coating. Two radii were then obtained, along the principal perpendicular directions of the surface curvature. A simple and efficient method to determine the experimental error on the stress calculation was developed taking into account the film thickness dispersion and the radii dispersion. Using constant deposition parameters, some samples…
Photocatalytic CO<inf>2</inf> Valorization by Using Ti<inf>O2</inf>, ZrO2 and Graphitic Based Semiconductors
2018
In this century, a broad scientific interest has been devoted to fulfill sustainable industrial processes and climatic change remediation. In this prospective, various green technologies have been studied to valorize CO 2• The aim of this research is the CO 2 reduction in presence of water by using the photocatalytic technology with nanomaterials as the photocatalysts. The present work overviews the main outcomes obtained by using graphitic and oxide based photocatalysts both in gas/solid and liquid/solid batch reactors under simulated solar light. In all gas/solid regime tests the major products detected were methane, carbon monoxide, and acetaldehyde.
A reliable procedure for the preparation of graphene-boron nitride superlattices as large area (cm x cm) films on arbitrary substrates or powders (gr…
2019
[EN] Herein, a reliable procedure for the preparation of graphene-boron nitride superlattices, either as films or powders, consisting of the pyrolysis at 900 degrees C of polystyrene embedded pre-formed boron nitride single sheets is reported. The procedure can serve to prepare large area films (cm x cm) of this superlattice on quartz, copper foil and ceramics. Selected area electron diffraction patterns at every location on the films show the occurrence of the graphene-boron nitride superlattice all over the film. The procedure can also be applied to the preparation of powdered samples on a gram scale. Comparison with other materials indicates that the superlattice appears spontaneously as…
Compressibility and structural stability of ultra-incompressible bimetallic interstitial carbides and nitrides
2012
We have investigated by means of high-pressure x-ray diffraction the structural stability of Pd 2Mo 3N, Ni 2Mo 3C 0.52N 0.48, Co 3Mo 3C 0.62N 0.38, and Fe 3Mo 3C. We have found that they remain stable in their ambient-pressure cubic phase at least up to 48 GPa. All of them have a bulk modulus larger than 330 GPa, the least compressible material being Fe 3Mo 3C, B 0 = 374(3) GPa. In addition, apparently a reduction of compressibility is detected as the carbon content is increased. The equation of state for each material is determined. A comparison with other refractory materials indicates that interstitial nitrides and carbides behave as ultra-incompressible materials. © 2012 American Physic…
Atomic Layer Deposition of Localized Boron- and Hydrogen-Doped Aluminum Oxide Using Trimethyl Borate as a Dopant Precursor
2020
Atomic layer deposition (ALD) of boron-containing films has been mainly studied for use in two-dimensional materials and for B doping of Si. Furthermore, lithium-containing borates show great promi...
Dopant radial inhomogeneity in Mg-doped GaN nanowires
2018
International audience; Using atom probe tomography, it is demonstrated that Mg doping of GaN nanowires grown by Molecular Beam Epitaxy results in a marked radial inhomogeneity, namely a higher Mg content in the periphery of the nanowires. This spatial inhomogeneity is attributed to a preferential incorporation of Mg through the m-plane sidewalls of nanowires and is related to the formation of a Mg-rich surface which is stabilized by hydrogen. This is further supported by Raman spectroscopy experiments which give evidence of Mg-H complexes in the doped nanowires. A Mg doping mechanism such as this, specific to nanowires, may lead to higher levels of Mg doping than in layers, boosting the po…