Showing papers by "James W. Mayer published in 1981"
TL;DR: In this article, the authors used ion-induced reactions in thin film systems to form equilibrium and metastable compounds, amorphous layers, and solid solutions, which can be obtained by splat-cooling or high dose plantation.
275 citations
TL;DR: The barrier heights depend primarily on the metal deposited and not on the particular silicide phase as mentioned in this paper, and the values of the barrier heights are 0.87 to 0.88 eV for PtSi.
Abstract: Deposited Ni, Pd, and Pt films on $n$-type Si have been annealed up to 700\ifmmode^\circ\else\textdegree\fi{}C. Silicide formation was monitored by MeV $^{4}\mathrm{He}$ Rutherford backscattering and glancing-angle x-ray diffraction. Barrier-height measurements were performed mainly using forward $I\ensuremath{-}V$ characteristics. The values of the barrier heights are 0.66 eV for ${\mathrm{Ni}}_{2}$Si and NiSi, 0.75 eV for ${\mathrm{Pd}}_{2}$Si; 0.85 eV for ${\mathrm{Pt}}_{2}$Si, and 0.87 to 0.88 eV for PtSi. The barrier heights depend primarily on the metal deposited and not on the particular silicide phase.
109 citations
TL;DR: In this article, the ion-induced atomic mixing process was used for the formation of metastable alloys in binary couples of Au and one of the fourth-period transition metals, such as Ni, Co, Fe or V.
104 citations
TL;DR: The valence level spectra of the Ni/Si and Pd/Si systems have been investigated using high-resolution x-ray photoelectron spectroscopy as discussed by the authors.
Abstract: The valence level spectra of the Ni/Si and Pd/Si systems have been investigated using high resolution x‐ray photoelectron spectroscopy. Temperature dependence studies for Ni deposited on thin thermal SiO2 demonstrate the importance of metal aggregation effects in the interpretation of binding energies as chemical shifts. Temperature studies for the Ni/Si system indicate that substantial chemical interaction occurs at the interface at temperatures as low as 100 K. These studies also show the presence of Ni in interstitial voids in the Si near the interface. A comparative study of the core and valence band features for the Ni and Pd silicides provides many valuable insights and a self‐consistent picture of the attendent valence charge redistribution and its influence on the observed chemical shifts.
83 citations
TL;DR: In this article, the ion-beam mixing behavior of four metal-semiconductor eutectic systems (Au, Si, Au, Ge, Al, and Ag) was investigated.
78 citations
TL;DR: In this article, it was found that reactions occur where Ni is deposited on Si at 10 to the -10th torr: Si atoms are displaced from lattice sites, the Ni atoms are in an Si-rich environment, and the Ni/Si interface is graded in composition.
Abstract: X-ray photoelectron spectroscopy and channeling measurements with MeV He-4(+) ions have been used to probe the structure of the interface in the Ni/Si system. It is found that reactions occur where Ni is deposited on Si at 10 to the -10th torr: Si atoms are displaced from lattice sites, the Ni atoms are in an Si-rich environment, and the Ni/Si interface is graded in composition. Composition gradients are present at both interfaces in the Si/Ni2/Si/Ni system. For the Ni-Si system, cooling the substrate to 100 K slows down the reaction rate. The temperature dependence of the interfacial reactivity indicates the kinetic nature of metal-semiconductor interfaces.
68 citations
TL;DR: In this paper, the effect of oxygen impurities on the Ni/Ni2Si interface has been investigated via ion implantation using x-ray photoelectron spectroscopy (XPS), 4He + backscattering, and 16O(d,alpha)14N nuclear reactions.
Abstract: The effect of oxygen impurities on the Ni/Ni2Si interface has been investigated via ion implantation using x-ray photoelectron spectroscopy (XPS), 4He + backscattering, and 16O(d,alpha)14N nuclear reactions. Oxygen dosages corresponding to peak concentrations of 1, 2, and 3 atomic percent were implanted into Ni films evaporated on Si (100) substrates. The oxygen, nickel, and silicon core lines were monitored as a function of time during in situ growth of the Ni silicide to determine the chemical nature of the diffusion barrier known to form in the presence of oxygen impurities. It is shown that neither Ni oxide or mixed compounds such as Ni2SiO4 are involved in the barrier formation. The data demonstrate that as the advancing Ni/Ni2Si interface encounters oxygen in the Ni film, silicon suboxides (Si2O3, Si2O, and SiO) are formed. As more oxygen is encountered, Si takes on a full coordination of oxygen, forming SiO2. When a sufficient layer of SiO2 has formed, Ni metal is no longer able to diffuse through to the Si/Ni2Si interface to continue the solid phase reaction. It has been determined under UHV annealing conditions that the amount of oxygen necessary to stop the Ni diffusion is 2.2×10^16 O/cm^2. These experiments also provide a novel approach for synthesizing Si oxides and suboxides in a metallic matrix for examining relaxation effects in XPS as well as providing model compounds for Si/SiO2 interfacial studies.
52 citations
TL;DR: In this article, ion-beam mixing of thin deposited Au and Co layers of compositions Au75Co25, Au50Co50, Au25Co75 and Au5Co95 was used for X-ray diffraction measurement.
Abstract: Supersaturated Au–Co solid solutions have been obtained by ion-beam mixing of thin deposited Au and Co layers of compositions Au75Co25, Au50Co50, Au25Co75 and Au5Co95. X-ray diffraction measurement...
15 citations
TL;DR: In this article, high power pulsed ion beams have been applied to anneal nickel thin films on silicon and epitaxial NiSi2 was formed at lower energy densities.
Abstract: High power pulsed ion beams have been applied to anneal nickel thin films on silicon. RBS and TEM have been performed to study ion beam induced effects. With Ba+ ion beams at energy densities greater than 0.7 J/cm2 and H+ beams above about 1.3 J/cm2, cellular structures were found. At about 0.6 J/cm2 for Ba+ (about 1.0 J/cm2 for H+), epitaxial NiSi2 was formed. At lower energy densities, polycrystalline layers containing a mixture of suicide phases were observed. With ion beam annealing, melting starts at the Ni/Si interface and epitaxy was found at energy densities well below that required to melt Ni or crystalline Si.
3 citations
TL;DR: In this article, the conductance of single crystal Au-doped Si and silicon-on-sapphire (SOS) was measured with 30 nsec ruby laser pulses.
Abstract: Measurements were made of the conductance of single crystal Au-doped Si and silicon-on-sapphire (SOS) during irradiation with 30 nsec ruby laser pulses. After the decay of the photoconductive response, the sample conductance is determined primarily by the thickness and conductivity of the molten layer. For the single crystal Au-doped Si, the solid-liquid interface velocity during recrystallization was determined from the current transient to be 2.5 m/sec for energy densities between 1.9 and 2.6 J/cm 2 , in close agreement with numerical simulations based on a thermal model of heat flow. SOS samples showed a strongly reduced photoconductive response, allowing the melt front to be observed also. For complete melting of a 0.4 μm Si layer, the regrowth velocity was 2.4 m/sec.
1 citations
TL;DR: In this paper, the formation and structure of epitaxial NiSi2 and CoSi2 thin films on silicon has been studied using transmission electron microscopy, which reveals the interface planes of faceted silicides through strain contrast, analogous to the contrast of the precipitate-matrix interface of coherent or semicoherent precipitates.
Abstract: Transmission electron microscopy has been applied to study the formation and structure of epitaxial NiSi2 and CoSi2 thin films on silicon. Bright field and dark field imaging reveal the interface planes of faceted silicides through the strain contrast, analogous to the contrast of the precipitate-matrix interface of coherent or semicoherent precipitates. Superlattice dark field imaging depicts the distribution of twin-related and epitaxial silicides in these systems. {111} interfaces were found to be more prominent than {001} interfaces. Twin-related silicides were observed to cover more area on the substrate silicon than epitaxial silicides did. In situ annealing of nickel and cobalt thin films on silicon provides a unique means of investigation of the transformation from polycrystalline to epitaxial silicides. The NiSi2 transformation was found to be very rapid at 820°C, whereas the CoSi2 transformation appeared to be very sluggish. Furnace annealing confirmed that only a small fraction of CoSi2 transforms to epitaxial CoSi2 after annealing at 850°C for 4h. Diffraction contrast analysis has been applied to interfacial dislocations of epitaxial NiSi2/Si and CoSi2/Si systems. The dislocations were found to be of edge type with $${\textstyle{1 \over 6}}\left\langle {112} \right\rangle $$
and $${\textstyle{1 \over 2}}\left\langle {110} \right\rangle $$
Burgers’ vectors. The average spacings are close to their respective theoretically predicted values.
TL;DR: In this article, the interfaces of epitaxial and non-epitaxial silicides and silicon were investigated by the direct lattice imaging method using cross-sectional samples.
Abstract: The interfaces of both epitaxial and non-epitaxial silicides and silicon were investigated by the direct lattice imaging method using cross-sectional samples. Non-epitaxial CoSi 2 on silicon was observed to have a curved interface. Epitaxial CoSi 2 , however, was found to be smooth within a facet. No evidence of an amorphous layer at the interface was obtained. Epitaxial NiSi 2 on Si(001) was found to be heavily faceted. The facets are on {111} and {100} planes with the former more frequently observed. The interface between Si(111) and NiSi 2 is also faceted but less so than that for Si(001). The interface is very rough on a large scale. Straight boundary lines corresponding to faceted planes were observed which indicated that the interfaces on an atomic scale were quite smooth. Defect clusters and planar defects were also observed at the interfaces.
TL;DR: In this paper, annealing of metal-Si structures, melting starts at the interface; epitaxial NiSi2 layers have been formed, and superlattice structures are formed in the epitaxia.
Abstract: Energy deposition and heat-flow determine the temperature distributions in pulsed-beam irradiated structures. In laser irradiated Si, transient conductance measurements indicated a liquid/solid interface velocity of 2.8 m/sec during crystallization in agreement with a heat flow model. With pulsed ion-beam annealing of metal-Si structures, melting starts at the interface; epitaxial NiSi2 layers have been formed. Ion-beam-mixing experiments on polycrystalline and epitaxial Au-Ag bilayers show that intermixing is more pronounced in the polycrystalline structures as is the case with thermal annealing. Superlattice structures are formed in the epitaxial structures.