A new and simple variable-angle accessory for infrared specular reflectance

A simple, low-cost accessory (patent pending) with only two flat mirrors and a new variable-angle mechanism has been developed for infrared specular reflectance measurements. The system allows the angles of incidence to be varied continuously from 15° (near normal incidence) to 85° (near grazing angle) without losing the alignment of the accessory. The reflectivity of boron nitride thin films deposited on metallic substrates has been measured at different angles of incidence to demonstrate the utility of this accessory

Dielectric characterization of multiferroic magnetoelectric double-perovskite Y(Ni0.5Mn0.5)O3 thin films

We report on functional properties of Y(Ni0.5Mn0.5)O3 epitaxial thin films, growth by pulsed laser deposition, observing clear features of its ferroelectric and ferromagnetic nature at cryogenic temperature. Temperature-dependent complex impedance spectroscopy (IS) characterization has shown a dielectric anomaly around the ferromagnetic Curie temperature ( 100 K) indicative of coupling between magnetic and electric orders

Polycrystalline silicon films obtained by hot-wire chemical vapour deposition

Silicon films were deposited at moderate substrate temperatures (280-500° C) from pure silane and a silane-hydrogen mixture (10% SiH 4, 90% H 2) in a hotwire CVD reactor. The morphology, structure and composition of the samples were studied with scanning electron microscopy, transmission electron microscopy, transmission electron diffraction, X-ray diffraction, Raman spectroscopy and secondary ion mass spectrometry. The sample deposited at 500° C with pure silane has an amorphous structure, whereas the samples obtained from silane diluted in hydrogen have a polycrystalline structure, even that grown at the lowest temperature (280° C). Polycrystalline samples have a columnar structure with 0.3-1 ?m crystallite sizes with preferential orientation in [220] direction. Deposition rates depend on the filament-substrate distance and range from 9.5 to 37 Å/s for the polycrystalline samples. The high quality of the polycrystalline samples obtained makes the hot-wire technique very promising. Moreover, it is expected to be easily scaled up for applications to large-area optoelectronic devices and to photovoltaic solar cells

Plasma-enhanced chemical vapor deposition of boron nitride thin films from B2H6-H2-NH3 and B2H6-N2 gas mixtures

Highly transparent and stoichiometric boron nitride (BN) films were deposited on both electrodes (anode and cathode) of a radio-frequency parallel-plate plasma reactor by the glow discharge decomposition of two gas mixtures: B2H6-H2-NH3 and B2H6-N2. The chemical, optical, and structural properties of the films, as well as their stability under long exposition to humid atmosphere, were analyzed by x-ray photoelectron, infrared, and Raman spectroscopies; scanning and transmission electron microscopies; and optical transmittance spectrophotometry. It was found that the BN films grown on the anode using the B2H6-H2-NH3 mixture were smooth, dense, adhered well to substrates, and had a textured hexagonal structure with the basal planes perpendicular to the film surface. These films were chemically stable to moisture, even after an exposition period of two years. In contrast, the films grown on the anode from the B2H6-N2 mixture showed tensile stress failure and were very unstable in the presence of moisture. However, the films grown on the cathode from B2H6-H2-NH3 gases suffered from compressive stress failure on exposure to air; whereas with B2H6-N2 gases, adherent and stable cathodic BN films were obtained with the same crystallographic texture as anodic films prepared from the B2H6-H2-NH3 mixture. These results are discussed in terms of the origin of film stress, the effects of ion bombardment on the growing films, and the surface chemical effects of hydrogen atoms present in the gas discharge

Internal stress and strain in heavily boron-doped diamond films grown by microwave plasma and hot filament chemical vapor deposition

The internal stress and strain in boron‐doped diamond films grown by microwave plasma chemical vapor deposition (MWCVD) and hot filament CVD (HFCVD) were studied as a function of boron concentration. The total stress (thermal+intrinsic) was tensile, and the stress and strain increased with boron concentration. The stress and the strain measured in HFCVD samples were greater than those of MWCVD samples at the same boron concentration. The intrinsic tensile stress, 0.84 GPa, calculated by the grain boundary relaxation model, was in good agreement with the experimental value when the boron concentration in the films was below 0.3 at.%. At boron concentrations above 0.3 at.%, the tensile stress was mainly caused by high defect density, and induced by a node‐blocked sliding effect at the grain boundar

P-doped polycrystalline silicon films obtained at low temperature by hot-wire chemical vapor deposition

P-doped polycrystalline silicon films were deposited over Corning 7059 substrates at a moderate temperature, 330°C, in a hot-wire reactor. The films were obtained from the decomposition of silane and hydrogen (10% SiH 4, 90% H 2) and different amounts of diborane. The structure and morphology of the samples were studied with X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). X-ray diffraction spectra show sharp diffraction peaks corresponding to silicon reflections, and Raman spectra show no evidence of amorphous phases and present a high intensity and narrow peak at 520 cm -1, which is the typical feature of crystalline silicon structure. The efficiency of boron incorporation was studied by secondary ion mass spectrometry (SIMS). The electrical properties of doped samples were also studied

P-doped polycrystalline silicon films obtained at low temperature by hot-wire chemical vapor deposition

P-doped polycrystalline silicon films were deposited over Corning 7059 substrates at a moderate temperature, 330°C, in a hot-wire reactor. The films were obtained from the decomposition of silane and hydrogen (10% SiH 4, 90% H 2) and different amounts of diborane. The structure and morphology of the samples were studied with X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). X-ray diffraction spectra show sharp diffraction peaks corresponding to silicon reflections, and Raman spectra show no evidence of amorphous phases and present a high intensity and narrow peak at 520 cm -1, which is the typical feature of crystalline silicon structure. The efficiency of boron incorporation was studied by secondary ion mass spectrometry (SIMS). The electrical properties of doped samples were also studied

Polycrystalline silicon films obtained by hot-wire chemical vapour deposition

Silicon films were deposited at moderate substrate temperatures (280-500° C) from pure silane and a silane-hydrogen mixture (10% SiH 4, 90% H 2) in a hotwire CVD reactor. The morphology, structure and composition of the samples were studied with scanning electron microscopy, transmission electron microscopy, transmission electron diffraction, X-ray diffraction, Raman spectroscopy and secondary ion mass spectrometry. The sample deposited at 500° C with pure silane has an amorphous structure, whereas the samples obtained from silane diluted in hydrogen have a polycrystalline structure, even that grown at the lowest temperature (280° C). Polycrystalline samples have a columnar structure with 0.3-1 ?m crystallite sizes with preferential orientation in [220] direction. Deposition rates depend on the filament-substrate distance and range from 9.5 to 37 Å/s for the polycrystalline samples. The high quality of the polycrystalline samples obtained makes the hot-wire technique very promising. Moreover, it is expected to be easily scaled up for applications to large-area optoelectronic devices and to photovoltaic solar cells

Crystal growth characterization of polycrystalline silicon films obtained by hot-wire chemical vapour deposition

Polycrystalline silicon (poly-Si) films were obtained at moderate temperatures (280-500ºC) from a mixture of silane and hydrogen in a hot wire CVD reactor. SEM and TEM results revealed a columnar growth of poly-Si grains with a preferential orientation of the crystals perpendicular to the substrate along the [110] direction. Plain view examinations along the [110] axis revealed a needled shape of the crystals 0.3-1 µm) with the largest axis randomly distributed on the plane. The high quality of the polycrystalline samples obtained makes the hot-wire technique very promising

Crystal growth characterization of polycrystalline silicon films obtained by hot-wire chemical vapour deposition

Polycrystalline silicon (poly-Si) films were obtained at moderate temperatures (280-500ºC) from a mixture of silane and hydrogen in a hot wire CVD reactor. SEM and TEM results revealed a columnar growth of poly-Si grains with a preferential orientation of the crystals perpendicular to the substrate along the [110] direction. Plain view examinations along the [110] axis revealed a needled shape of the crystals 0.3-1 µm) with the largest axis randomly distributed on the plane. The high quality of the polycrystalline samples obtained makes the hot-wire technique very promising