Search

Reports that pulsed glow discharge plasma from a 1 Pa gas mixture of acetylene and hexafluoroethane was used to produce fluorinated diamond-like carbon (FDLC) films on glass and polymethyl-methacrylate substrate. Composition of the FDLC coatings; Transmittance, absorption coefficient and optical band gap of 100 nm thick FDLC coatings.

Presents a study that analyzed ion irradiation-induced grain growth in palladium polycrystalline thin films. Methodology; Determination of the size of the grains; Examination of the changes in grain size distribution after irradiation.

Presents a study which investigated initial phase formation and dissociation in the thin-film nickel/aluminum system. Method of the study; Results and discussion; Conclusion.

Stress in crystalline TiN/amorphous B-C-N multilayered thin films has been determined by the substrate curvature technique. It is established that the total stress is dependent on the number of deposited bilayers and on the bilayer repeat length. The linear relationship between the stress and the inverse of the bilayer repeat length allows calculation of the value of the interface stress. It is found to be compressive with a value between 1.79 and 2.46 J/m[sup 2], depending on the calculation method. An apparent dependence between the interface stress and the total thickness of the multilayer film is observed. It is interpreted as an additional relaxation due to an increase of the roughness of the interfaces when the number of deposited bilayers is increased. © 1997 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a study that examined the properties of ion-implanted iron-titanium surface thin films. Methodology; Analysis of the microstructure of the thin films; Determination of the wear scars and friction coefficients of the thin films.

Ternary Zn1-xCdxO films were grown on (0001) sapphire substrates by pulsed laser deposition. The energy band gap of Zn1-xCdxO films decreases with increasing Cd content. An increase of Cd content also leads to the emission broadening, absorption edge broadening, and crystallinity degradation. The absorption edge and ultraviolet emission energy shift to lower energy from 3.357 eV to 3.295 eV and 3.338 eV to 3.157 eV, respectively, with increasing Cd content from 0.3% to 3% at 4 K. The Stokes’ shift between the absorption and emission is observed and that indicates the increase of exciton localization with Cd content. [ABSTRACT FROM AUTHOR]

Presents information on a study that demonstrated a process for the formation of thin metallic, oriented crystalline nickel silicon[sub2] on amorphous silicon dioxide/silicon. Research method; Results and discussion.

Abstract: The tuning of the optical band gap in the range of E Tauc=0.96–4.31 eV was demonstrated in the Si–N–C films grown by pulsed glow discharge deposition. The films were grown at room temperatures from the following precursor gases: silane (SiH4), nitrogen (N2), and acetylene (C2H2). The stoichiometry of the films was varied by changing the flow of acetylene gas in the deposition chamber. The properties of the films were characterized using Rutherford backscattering (RBS), Elastic Recoil Detection analysis (ERD), profilometry, nanoindentation, UV–visible and infrared spectroscopies. All films demonstrated high hardness between 11.6 and 15.6 GPa, which makes them a valuable material for technologies requiring hard scratch resistant coatings with a tunable band gap. [Copyright &y& Elsevier]

Bulk austenitic stainless steels (SS) have a face-centered cubic (fcc) structure. However, sputter deposited films synthesized using austenitic stainless steel targets usually exhibit body-centered cubic (bcc) structure or a mixture of fcc and bcc phases. This paper presents studies on the effect of processing parameters on the phase stability of 304 and 330 SS thin films. The 304 SS thin films with in-plane, biaxial residual stresses in the range of approximately 1 GPa (tensile) to approximately 300 MPa (compressive) exhibited only bcc structure. The retention of bcc 304 SS after high-temperature annealing followed by slow furnace cooling indicates depletion of Ni in as-sputtered 304 SS films. The 330 SS films sputtered at room temperature possess pure fcc phase. The Ni content and the substrate temperature during deposition are crucial factors in determining the phase stability in sputter deposited austenitic SS films. [ABSTRACT FROM AUTHOR]

Materials with Si–C–N composition are of great interest due to their remarkable properties such as high hardness and oxidation resistance. In this study amorphous silicon nitride and silicon carbonitride films were deposited on glass, fused silica, and carbon substrates by the plasma immersion ion processing technique. Gas pressure during the deposition was kept around 0.13 Pa (1 mTorr) and SiH4, N2, Ar and C2H2 gas mixtures were used. Film hardness, composition and UV–visible optical absorption were characterized using nanoindentation, ion beam analysis techniques, and UV–visible spectroscopy, respectively. The films exhibit high transparency in the visible and near UV regions. Addition of the carbon to the films causes decrease in the density of the films, as well as decrease in hardness and transparency. These results suggest that in the low energy regime of PIIP the deposition of hard carbon composites with nitrogen and silicon does not take place. [Copyright &y& Elsevier]

Introduces a novel setup that combines energy-dispersive x-ray diffraction and ion-channeling capabilities for damage studies on single-crystalline thin films irradiated with 100-720 keV heavy ions. Measurement of damage-related lattice strain; Provision of information on bombardment-induced disorder complementary to the channeling technique.

Luminescent, cerium doped Lu2SiO5 thin films with C2/c symmetry have been prepared by pulsed laser deposition (PLD) at temperatures much lower than the crystallization temperature (2150 °C) of the corresponding bulk crystals. The PLD grown films show the typical luminescence resulting from the Ce3+ 5d-4f transition. Maximum luminescence efficiency was observed for films prepared at an oxygen partial pressure of 200 mTorr at 600 °C. These conditions reflect a balance between Ce4+/Ce3+ interconversion and the crystalline quality of the films. The results indicate that PLD offers a low temperature deposition technique for complex oxide phosphor materials. [ABSTRACT FROM AUTHOR]

We have developed an innovative approach without the use of ion implantation to transfer a high-quality thin Si layer for the fabrication of silicon-on-insulator wafers. The technique uses a buried strained SiGe layer, a few nanometers in thickness, to provide H trapping centers. In conjunction with H plasma hydrogenation, lift-off of the top Si layer can be realized with cleavage occurring at the depth of the strained SiGe layer. This technique avoids irradiation damage within the top Si layer that typically results from ion implantation used to create H trapping regions in the conventional ion-cut method. We explain the strain-facilitated layer transfer as being due to preferential vacancy aggregation within the strained layer and subsequent trapping of hydrogen, which lead to cracking in a well controlled manner. [ABSTRACT FROM AUTHOR]

We have epitaxially deposited Ba0.6SrO0.4TiO3 (BST) thin films on SiO2/Si substrates using pulsed laser deposition by introducing biaxially oriented ion-beam-assisted-deposited MgO as templates. The structural properties of the BST films were strongly affected by the crystallinity of the templates. The dielectric loss of the BST film was found to decrease as its in-plane texture alignment was improved. As a result, a relatively larger figure of merit K value, defined as tunability/loss, was obtained for the films with better in-plane crystallinity. The K factor ranged between 7.5 and 3.5 when the in-plane alignment of the MgO templates was varied from 5.00 to 10.5°. This work demonstrates that the crystalline quality of the template layers plays a critical role in monolithic integration of BST with SiO2/Si for frequency agile devices. [ABSTRACT FROM AUTHOR]

Diamond-like carbon films were deposited using pulsed glow discharge deposition at 4 kV. The duty factor was varied and all other parameters were kept constant. It was shown that the contribution of neutral particles to the total number of deposition atoms is much larger than that of energetic ions. At the same time, there is a relationship between the deposition of neutral particles and ion bombardment. The sticking coefficient of the neutral particles in proportional to the flux of energetic ions and does not exceed 5×10-4 for the deposition parameters used in our experiment. [ABSTRACT FROM AUTHOR]

Zn1-xCdxO thin films were deposited on (0001) sapphire substrates by pulsed-laser deposition. Structural and optical properties of Zn1-xCdxO films were strongly correlated to the processing conditions. The composition of the films varied nonmonotonically as a function of deposition temperatures due to the difference of vapor pressure between Cd and Zn species. The optical energy bandgap of Zn1-xCdxO thin films, measured by photoluminescence and transmittance, changed from 3.249 to 3.291 eV. The change of the optical properties was mainly attributed to the change of the stoichiometry of Zn1-xCdxO, as determined by Rutherford backscattering spectroscopy. [ABSTRACT FROM AUTHOR]

Magnetron-sputter-deposited austenitic 330 stainless steel (330 SS) films, several microns thick, were found to have a hardness ∼6.5 GPa, about an order of magnitude higher than bulk 330 SS. High-resolution transmission electron microscopy revealed that sputtered 330 SS coatings are heavily twinned on {111} with nanometer scale twin spacing. Molecular dynamics simulations show that, in the nanometer regime where plasticity is controlled by the motion of single rather than pile-ups of dislocations, twin boundaries are very strong obstacles to slip. These observations provide a new perspective to producing ultrahigh strength monolithic metals by utilizing growth twins with nanometer-scale spacing. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Thin-film alloy samples of Al/NixAl1-x/Ni (x=0.75, 0.5, 0.25) were irradiated at room temperature and at 160 °C with 280 and 560 keV Xe ions to a dose of 1.1×1016 Xe ions/cm2. The samples were analyzed by Rutherford backscattering spectrometry. In the Al/Ni3Al/Ni configuration the Ni3Al layer mixes more strongly with Al than with Ni. In the Al/NiAl/Ni samples, the NiAl layer mixes substantially with both Al and Ni. In the Al/NiAl3/Ni case, the NiAl3 layer mixes only with Ni. The results differ from thermal annealing behavior and are explained in terms of the thermodynamical driving forces present in the different samples. [ABSTRACT FROM AUTHOR]

A thin-film technique for measuring the chemical composition of Y-Ba-Cu-O thin films to a few percent accuracy is described. This technique utilizes non-Rutherford backscattering of 8.8 MeV helium ions, which has an increased sensitivity 16O by a factor of 25 over Rutherford backscattering spectrometry. The ratios of the cross sections for He++ scattered from oxygen, copper, and yttrium relative to barium are easily determined using thin-film standards that can be fabricated in any deposition system capable of producing thin-film superconductors. The technique does not require the constant use of standards or accurate charge determination. [ABSTRACT FROM AUTHOR]

We have fabricated superconducting thin films by ion implanting Y into a base material formed by the coevaporation of BaF2 and Cu. The implantations were carried out at 77 K and resulted in the formation of an amorphous Y-Ba-Cu-F surface layer. Oxygen annealing with the addition of water vapor renders the base material insulating with a room-temperature resistance of 105 Ω. An identical annealing treatment on the Y-implanted material produces a superconductor with an onset temperature of 85 K. [ABSTRACT FROM AUTHOR]

In this paper, helium (He) ion irradiations with various fluences were performed on sputtered Cu thin films with a mosaic structure to evolve biaxial stress. X-ray diffraction of the θ–2θ method was used to determine the residual strains in the thin films by measuring the spacing of the crystallographic planes. The results show the in-plane biaxial tensile stress has been reduced by ion irradiation. A new proposed model is discussed to explain the ion-irradiation-induced stress release in mosaic structured Cu thin films. [ABSTRACT FROM AUTHOR]

We have used differential scanning calorimetry to measure the heat capacity of diamond-like carbon (DLC) film prepared by a plasma immersion ion processing method. The same calorimeter was used to measure the heat capacity of single crystal natural diamond and of high purity graphite. The amount of atomic hydrogen trapped in the DLC films was determined by elastic-recoil-detection spectrometry. The present data and literature values were used to deduce an expression for the specific heat that factors out the contribution from the sp[sup 3]/sp[sup 2] bonding and from the atomic hydrogen trapped in the carbon. The data shows that the hydrogen contribution to the specific heat of carbon is independent of the sp[sup 3]/sp[sup 2] bonding and amounts to about 0.63k[sub B] per hydrogen atom. We propose a simple method to determine the sp[sup 3]/sp[sup 2] bonding ratio in hydrogenated DLC films based on measuring the specific heat and the hydrogen content of the sample. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Cr films sputtered onto {100} Si substrates at room temperature were found to be under residual tension, as revealed by wafer curvature measurements. A 150 nm thick Cr film was bombarded with 300 keV Ar ions after deposition. The intrinsic residual tensile stress increased slightly and then decreased with further increase in the ion dose. For ion doses >1×10[sup 15] ions/cm[sup 2], the stress in the film became compressive and increased with increasing dose. Transmission electron microscopy revealed that the grain boundaries in as-deposited Cr have columnar porosity. A Cr film, ion irradiated to a dose of 5×10[sup 15] ions/cm[sup 2], showed no grain boundary porosity. The changes in the residual stress during ion irradiation are explained by considering Ar incorporation in the film and the manner in which irradiation may change the interatomic distances and forces. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Abstract: Ion beam processing of organic/inorganic thin films can provide an alterative means to heat treatment in converting the films to their final desired mechanical properties. In this study, hybrid sol–gel derived thin films based on TEOS (tetraethylorthosilicate Si(OC2H5)4) and MTES (methyltriethoxysilane CH3Si(OC2H5)3) were prepared and deposited on Si substrates by spin coating. After the films were allowed to air dry they were heat treated at 300°C for 10min. Ion irradiation was carried out at room temperature using 2MeV Cu2+, 115keV He+ and 115keV H+ ions. Ion fluence was varied such that the electronic energy deposited to the film surface region was kept constant for the three different ions. Hardness and H loss in the films were measured after irradiation and were found to depend on the incident ion species. Both hardness and H loss were found to have a linear dependence with ion electronic stopping power. [Copyright &y& Elsevier]

Irradiation-induced changes in the structural and mechanical properties of nanocrystalline Fe, amorphous silicon oxycarbide (SiOC), and Fe/SiOC nanolaminate films were studied using X-ray diffraction, atomic force microscopy, scanning/transmission electron microscopy, and micro/nanoindentation. The films were fabricated by magnetron sputtering and then irradiated at room temperature with 3.5 MeV Fe ions to damage levels of 10, 20, or 50 displacements per atom (dpa). Irradiation of the Fe films was found to increase the compressive residual stress and hardness. For the SiOC films, irradiation led to densification and a subsequent increase in elastic modulus and hardness. The as-deposited Fe/SiOC nanolaminate with individual layer thicknesses of 72 ± 10 nm exhibited a higher hardness compared to the Fe and SiOC films. Furthermore, cross-sectional scanning/transmission electron microscopy of the Fe/SiOC nanolaminate after indentation showed a reduction in the thickness of both the Fe and SiOC layers with no evidence of cracks, shear bands or interface delamination. The combination of increased hardness and deformability of the Fe/SiOC nanolaminate is the result of homogenous plastic co-deformation in the Fe and SiOC layers through the constraint of localized shear flow in the SiOC. Although irradiation of the Fe/SiOC nanolaminate led to recoil mixing of Fe into the SiOC layers, the nanolayered structure remained intact. Increasing the irradiation damage level from 10 to 50 dpa led to more recoil mixing and also a reduction in elastic modulus and hardness of the Fe/SiOC nanolaminate. The study suggests Fe/SiOC nanolaminates are a promising class of irradiation tolerant materials. [ABSTRACT FROM AUTHOR]

Abstract: Epitaxial anatase films with thickness of around 300nm were deposited on and irradiated with 250keV Ne ions at room temperature. X-ray diffraction, Rutherford backscattering spectrometry, and transmission electron microscopy were used to characterize the microstructural changes under irradiation. Two primary features are observed in the irradiated material: a damaged layer with a high density of nano-sized defects including dislocation loops was observed in the film and, near the interface, a defect denuded zone formed on the side while an amorphous layer formed on the side. Atomistic calculations attribute the formation of both the defect-denuded zone and the interfacial amorphous layer not to the interaction between the irradiation induced defects and the hetero-interface but rather differences in chemical potential and mobilities for defects in each of the two phases. [Copyright &y& Elsevier]

Abstract: Ion beam processing of organic/inorganic thin films has been shown to be an effective means in converting polymeric films into their final ceramic-like state. In this study, hybrid sol-gel derived thin films based on TEOS (tetraethylorthosilicate) Si(OC2H5)4 and MTES (methyltriethoxysilane) CH3Si(OC2H5)3 were prepared and deposited on Si substrates by spin coating. After the films were allowed to air dry, they were heat treated at 300°C for 10min. Ion irradiation was performed at room temperature using 125keV H+ and 250keV N2+ ions with fluences ranging from 1×1014 to 5×1016 ions/cm2. FT-IR and Raman spectroscopies were used to quantify the chemical structural transformations which occurred including the evolution of the organic components, the cross-linking of silica clusters, and the clustering of carbon. [Copyright &y& Elsevier]

Abstract: A study of the effects of ion irradiation on the surface mechanical behavior and shrinkage of organic/inorganic modified silicate thin films was performed. The films were synthesized by sol–gel processing from tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) precursors and spin-coated onto Si substrates. The sol viscosity and the spin velocity were adjusted so that the films produced had a final thickness ranging from 580 to 710nm after heat treatment. The ion species and incident energies used were selected such that the projected ion range was greater than the film thickness, resulting in fully irradiated films. After heat treatment at 300°C for 10min, the films were irradiated with 125keV H+, 250keV N2+ and 2MeV Cu+ ions with fluences ranging from 1×1014 to 1×1016 ions/cm2. Both hardness and reduced elastic modulus were seen to exhibit a monotonic increase with fluence for all three ion species. Also, H loss was found to increase monotonically with increase in fluence, while the film thickness was found to decrease with increase in fluence. [Copyright &y& Elsevier]

Abstract: A study of the effects of H+ implantation on the photoluminescence (PL) and carrier mobility of ZnO thin films is presented. The 4.2K PL of the as-grown films exhibits free-exciton luminescence at 3.3755eV and strong bound-exciton luminescence between 3.33 and 3.37eV including a peak observed at 3.3313eV which is identified as the collapse of excitons bound to structural defects. While the implantation process results in a slight reduction of the overall PL intensity due to the introduction of nonradiative centers, the intensity of the 3.3313eV bound-exciton peak is reduced by more than two orders of magnitude. We attribute this reduction to preferential interaction of hydrogen with structural defects, such as passivation or the formation of complex defects. Room temperature Hall measurements show that changes in the optical properties of H-implanted ZnO are also accompanied by an increased carrier concentration and decreased carrier mobility. [Copyright &y& Elsevier]

Abstract: The effects on fluorine incorporation on the structure and optical properties of amorphous hydrogenated silicon carbide films deposited by pulsed glow discharge were investigated. Fluorine is incorporated at the expense of silicon, and films with up to 16 at.% of fluorine were obtained as determined by ion beam analysis. Structural investigation was carried by Raman and infrared spectroscopies. Infrared results showed that incorporation of fluorine occurs in the form of Si–F bonds, and Raman results showed a progressive formation of graphitic agglomerates due to fluorine incorporation in the films. Because of the relatively high bonding energy of Si–F, preferential bonding of fluorine with silicon induces small changes in the optical gap. [Copyright &y& Elsevier]

Abstract: Hybrid organic/inorganic modified silicate thin films were synthesized by sol–gel processing from tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) precursors and spin-coated onto (100) Si substrates. A comparison was made of films which were heat treated at temperatures ranging from 300°C to 800°C and a film which was first heat treated at 300°C and subsequently irradiated using 2MeV He+ ions with a fluence of 3×1015 ions/cm2. Nanoindentation was used to measure the hardness and reduced elastic modulus, both of which exhibited an order of magnitude increase after irradiation. The increase in hardness and reduced elastic modulus of the irradiated film was accompanied by a 50% reduction in H concentration. X-ray photoelectron spectroscopy was also employed to examine the changes in C, O and Si composition resulting from heat treatment and ion irradiation. [Copyright &y& Elsevier]