High sputtering yields of organic compounds by large gas cluster ions

We measured the sputtering yield, surface roughness and surface damage of thin leucine films bombarded with Ar cluster ions and examined the usefulness of large gas cluster ions for the depth profiling of organic compounds. Ar cluster ion beams with a mean size of 2000 atoms/cluster and energies from 5 to 30 keV were used. Sputtering yields increased linearly with incident ion energy and were extremely high compared to inorganic materials. Surface damage was investigated by measuring positive secondary ions emitted from the leucine film before and after cluster ion irradiation. After irradiation the leucine surface became smoother. The yield ratio of protonated leucine ions to other fragment ions kept constant before and after Ar cluster ion irradiation. These results indicate that large gas cluster ions are useful for depth profiling of organic compounds.     

Low energy (⩽ 100 eV) sputtering of thin molybdenum nitride films

Molybdenum nitride films formed by 100 eV N⁺₂ bombardment to saturation of polycrystalline Mo have been sputtered to high fluence by normally incident 100 eV Ar⁺ and He⁺ and 15 eV Ne⁺ while the surface nitrogen concentration was monitored by Auger electron spectroscopy (AES). The penetration distance of nitrogen atoms during film formation and subsequent sputtering is assumed to be small enough that AES will detect, to some degree, all of the nitrogen in the film. The nitrogen AES signal decays exponentially to unsputterable levels for the 15 eV Ne⁺ and 100 eV He⁺ cases and decays bi-exponentially to near the bulk contamination level for the 100 eV Ar⁺ case. The results are interpreted according to existing concepts, but the kinetics of nitrogen loss is modeled using a two-layer adaptation of the standard model for adsorbate monolayer sputtering kinetics. Fitting our proposed model to the data yields apparent cross-sections which are interpreted as composites of cross-sections for experimentally indistinguishable elementary processes; these elementary cross-sections for each process are geometrical averages on the polycrystalline surface. Processes considered, in addition to nitrogen sputtering, include bombardment-induced transport of nitrogen within the film and sputtering of the Mo lattice itself.     

Jetlike component in sputtering of LiF induced by swift heavy ions

Angular distributions of sputtered atoms from SiO2 and LiF single crystals were measured under the irradiation of 1 MeV/u swift heavy ions. In contrast to the almost isotropic distribution of SiO2, an additional jetlike component was observed for LiF. The total sputtering yield of SiO2 ( approximately 10(2) atoms/ion) can be reproduced by an extended inelastic thermal spike model, whereas the huge yield of LiF ( approximately 10(4) atoms/ion) needs a substantial decrease of the sublimation energy to be described by the model.     

Effect of nitrogen pressure on the combustion synthesis of titanium nitride

Abstract

Titanium nitride, TiN, has attractive physical and chemical properties such as hardness, chemical stability and electrical conductivity. It is a typical material with a wide range of stoichiometry. It can be synthesised by high pressure combustion synthesis. The composition and microstructures can vary with the experimental conditions especially with thermal treatment and nitrogen pressure.     

Oxidation of vanadium nitride and titanium nitride coatings

The oxidation of vanadium nitride (VN) and titanium nitride (TiN) coatings in ultra-high vacuum has been investigated in situ by X-ray photoelectron spectroscopy. On the VN coatings mixed oxide layers containing V³⁺ and V⁴⁺ species form at elevated temperatures (?600°C) and at high oxygen exposures, which cover completely the VN surface. Under similar oxidation conditions the TiN surface oxidises partially to a mixture of TiO₂ and Ti oxynitride (TiO_xN_y) phases. This oxidation behaviour has been correlated to the tribological properties of the VN and TiN coatings investigated recently.     

Production of carbon-nitrogen coatings modified by titanium nitride

We offer a method of producing composite coatings based on carbon-nitrogen compounds modified by titanium nitride clusters. The structure of the material obtained is studied by transmission electron microscopy. A comparison between electron diffraction patterns from carbon-nitrogen and titanium-nitride modified coatings reveals the presence of a hexagonal syngony in the carbon-nitrogen condensate. The mech-anism of the modification effect on the structure and properties of the obtained coating is discussed.     

Properties of amorphous carbon nitride prepared by RF reactive sputtering

The local microstructure and optical and electrical properties were investigated of amorphous carbon nitride (a-CN) films deposited by reactive radio-frequency (RF) sputtering. Two series prepared in nitrogen or in a nitrogen and argon mixture were studied. The optical properties were investigated by transmittance/reflectance and photothermal deflection spectroscopies. Combined infrared measurements and Raman scattering spectroscopies were used to investigate the microstructure of a-CN films in terms of nitrogen incorporation within the films and C sp ² content. These experiments were completed by dark electrical conductivity measurements performed in coplanar configuration in the temperature range 50–450?K. The films exhibit semiconductor behaviour and the temperature dependence suggests two types of conduction. An increase in nitrogen incorporation induces an increase with clustering of sp ² phase replacing C=C olefinic groups with aromatic groups.     

微波ECR等离子体增强磁控溅射制备SiNx薄膜及其性能分析

利用微波ECR磁控反应溅射法在室温下制备无氢SiN_x薄膜.通过傅里叶红外光谱 、X射线电子谱、膜厚仪、纳米硬度仪、原子力显微镜等分析手段，分析了N₂流 量、Si靶溅射功率等实验参数对SiN_x薄膜结构、化学配比以及机械性质的影响. 结果表明，SiN_x薄膜中Si-N结构、化学配比及机械性质与等离子体中的Si元素 含量关系密切，随着N₂流量的增加或者Si靶溅射功率的降低，等离子体中的Si 元素含量降低，SiN_x薄膜结构、化学配比及硬度发生变化，红外光谱发生偏移 ，硬度下降，沉积速率降低. 关键词： x')" href="#">SiN_x 磁控溅射 傅里叶变换红外吸收光谱 X射线电子谱     

用射频溅射法制备立方氮化硼薄膜

利用射频溅射方法在n型Si(111)衬底上制备出立方相含量接近100%且粘附性较高的立方氮化硼(c-BN)薄膜.傅里叶变换红外谱(FTIR)的结果表明，基底负偏压对薄膜立方相含量和薄膜压应力有很大影响，另外，衬底的电阻率对c-BN生长和薄膜的压应力也有一定的影响. 关键词： 立方氮化硼 射频溅射 压应力 基底负偏压     

Passivation of GaAs surface by atomic-layer-deposited titanium nitride

The suitability of titanium nitride (TiN) for GaAs surface passivation and protection is investigated. A 2-6-nm thick TiN passivation layer is deposited by atomic layer deposition (ALD) at 275 ° C on top of InGaAs/GaAs near surface quantum well (NSQW) structures to study the surface passivation. X-ray reflectivity measurements are used to determine the physical properties of the passivation layer. TiN passivation does not affect the surface morphology of the samples, but increases significantly the photoluminescence intensity and carrier lifetime of the NSQWs, and also provides long-term protection of the sample surface. This study shows that ALD TiN coating is a promising low-temperature method for ex situ GaAs surface passivation.     

Molecular sputtering of fullerite by low-energy bismuth ions

Physics of the Solid State - The interaction of low-energy bismuth ions with a fullerite surface at ion energies in the range from 50 to 200 eV and at target temperatures from 100 to 270°C has...     

Growth, structural, and magnetic properties of iron nitride thin films deposited by dc magnetron sputtering

FeN thin films were deposited on glass substrates by dc magnetron sputtering at different Ar/N₂ discharges. The composition, structure and the surface morphology of the films were characterized using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and atomic force microscopy (AFM). Films deposited at different nitrogen pressures exhibited different structures with different nitrogen contents, and the surface roughness depended on the mechanism of the film growth. Saturation magnetization and coercivity of all films were determined using superconducting quantum interference device, which showed that if N₂/(Ar+N₂) flow ratio was equal to or larger than 30% the nonmagnetic single-phase γ″-FeN appeared. If N₂/(Ar+N₂) flow ratio was less than 10%, the films consisted of the mixed phases of FeN_0.056 and γ′-Fe₁₆N₂, whose saturation magnetizations were larger than that of -Fe. If N₂/(Ar+N₂) flow ratio was 10%, the phases of γ′-Fe₄N and -Fe₃N appeared, whose saturation magnetizations were lower than that of -Fe.     

Thermal evolution and stability of a tin nitride obtained by reactive sputtering

Tin nitride obtained by reactive magnetron sputtering was annealed at several temperatures to study the thermal evolution and stability of the compound. X-ray diffraction, thermal effusion and conversion electron Mössbauer spectrometry were used to characterize the events. The nitride has different stabilities, depending on the ambient conditions under which the annealings are performed. Apparently only one crystallographic phase of the nitride is present before it disproportionates.     

Complex study of titanium nano-films prepared by magnetron sputtering

The oxidation of Ti films with thickness from 5 to 100 nm was performed in air at room temperature. The thickness and roughness of metal and oxide layers were determined by neutron and X-ray reflectometry. The thin titanium films were found to be oxidized to a greater depth; than the thick ones. However the metal layer was found to exist even in the thinnest (5 nm) samples, as the direct measuring of electrical resistance of the films has confirmed. The optimal parameters of titanium films utilizable in polarizing coatings of neutron optics were estimated. The AFM data on the microrelief and the phase homogeneity of the Ti nano-film surface were obtained.     

Structure, electrical and chemical properties of zirconium nitride films deposited by dc reactive magnetron sputtering

2 and Ar ambient. X-ray diffraction indicated that growth of ZrN with a preferred (111) orientation over Si(100) was achieved. The resistivity of the films varies from 200 μΩcm to 15 μΩcm depending on the N₂ content in the working gas. The square resistance of the films deposited on 96% Al₂O₃ ceramic wafers is stable below 300 °C. Received: 17 June 1996/Accepted: 9 December 1996     

Emission of charged clusters during metal sputtering by ions

A method for simulating processes of metal sputtering by ion bombardment in the form of large neutral and charged clusters with a number of atoms N≥5 based on simple physical assumptions and in fair agreement with experiment is suggested. As an example, the ionization degrees and ionization coefficients, as well as the relative cluster yields, are calculated as a function of the number of atoms in clusters of different metals (Ag, Nb, and Ta) bombarded by singly charged Ar⁺¹ and Au⁻¹ ions. A fluctuation mechanism of charge state formation for large clusters, which describes the dependence of the charge state distributions on cluster size and target temperature, is developed.     

Structure and mechanical properties of titanium nitride/carbon nitride multilayers

The structure and mechanical properties of the multilayers consisting of 5-73 nm thick titanium nitride (TiN) and 4.6 nm thick carbon nitride (CN) have been investigated. It has been found that the CN layers are amorphous and the TiN layers thinner than 17 nm are amorphous. The TiN layers become crystallized as the thickness is increased to 30 nm or thicker. The hardness from the composite response of the multilayered films and their substrates determined using continuous stiff measurement is smaller than the film-only hardness (without substrate effects) calculated using Bhattacharya-Nix empirical equation. The hardness increases with raising the thickness of TiN layers. With the crystallization of the TiN layer, the multilayers become even harder than that calculated based on the rule of mixtures. However, no enhancement in hardness has been observed when the TiN layers are amorphous.