Reversible phase transformation in the Pd2Si-PdSi thin-film system

The thermal stability of thin PdSi films has been studied at temperatures ranging between 300 and 700 °C. The PdSi, when in contact with crystalline Si, transforms into Pd2Si and Si at temperatures of 500–700 °C, a process contrary to the equilibrium-phase diagram. The rate of transformation was found to depend on the structure and orientation of the Si. Upon heating above 750 °C, Pd2Si transforms back to PdSi. However, PdSi is stable against annealing when in contact with Pd2Si or an inert substrate SiO2. We propose that the decomposition of PdSi into Pd2Si and Si in the presence of crystalline Si is due to a lower interface energy of the Pd2Si-Si interface compared to that of the PdSi-Si interface

Relationship of the 3P0 decay model to other strong decay models

The 3P0 decay model is briefly reviewed. Possible improvements, partly motivated by the examination of a microscopic description of a quark - anti-quark pair creation, are considered. They can provide support for the one-body character of the model which, otherwise, is difficult to justify. To some extent, they point to a boost effect that most descriptions of processes involving a pair creation cannot account for.Comment: 4 pages, 2 .eps figures; Contribution to the BARYONS 2002 Conference, 3.-8. March 2002, JLab, US

Ion mixing of markers in SiO2 and Si

The amount of atomic mixing in amorphous SiO2 and Si is studied by measuring the redistribution of thin metal markers due to irradiation with 300-keV Xe+ ions. In SiO2, the mixing efficiency appears to be independent of the chemical nature of marker atoms and can be explained in terms of a linear cascade model. In Si, the mixing is found to correlate with thermally activated diffusivities of the marker species

Kinetics and moving species during Co2Si formation by rapid thermal annealing

We have investigated the growth kinetics and identified the moving species during Co2Si formation by rapid thermal annealing (RTA). For the kinetics study, samples which consisted of a thin Co film on an evaporated Si substrate were used. To study which species moves, samples imbedded with two very thin Ta markers were employed. Upon RTA, only one silicide phase, Co2Si, was observed to grow before all Co was consumed. The square root of time dependence and the activation energy of about 2.1±0.2 eV were observed during the Co2Si formation up to 680 °C. The marker study indicated that Co is the dominant mobile species during Co2Si formation by RTA. We conclude that Co2Si grows by the same mechanisms during RTA and conventional thermal annealing

Silicon resistor to measure temperature during rapid thermal annealing

A resistor composed of a piece of Si wafer and two thin silver wires attached to it, can reliably sense the temperature during rapid thermal annealing (RTA). As constant electric current passes through the Si piece, the resistivity change of Si with temperature produces a voltage signal that can be readily calibrated and converted to an actual temperature of the samples. An accuracy better than ±10 °C is achieved between 300° and 600 °C

Sequence of phase formation in planar metal-Si reaction couples

A correlation is found between the sequence of phase formation in thin-film metal-Si interactions and the bulk equilibrium phase diagram. After formation of the first silicide phase, which generally follows the rule proposed by Walser and Bené, the next phase formed at the interface between the first phase and the remaining element (Si or metal) is the nearest congruently melting compound richer in the unreacted element. If the compounds between the first phase and the remaining element are all noncongruently melting compounds (such as peritectic or peritectoid phases), the next phase formed is that with the smallest temperature difference between the liquidus curve and the peritectic (or peritectoid) point

Absorption in quantum electrodynamics cavities in terms of a quantum jump operator

We describe the absorption by the walls of a quantum electrodynamics cavity as a process during which the elementary excitations (photons) of an internal mode of the cavity exit by tunneling through the cavity walls. We estimate by classical methods the survival time of a photon inside the cavity and the quality factor of its mirrors

Ion mixing to produce amorphous Mo-Ru superconducting films

Amorphous Mo55Ru45 alloy films were formed by ion mixing of multilayered samples. The ion mixed films, which contain no metalloid element, show excellent superconducting properties. The measured properties are correlated with the microstructure obtained by both x-ray diffraction and transmission electron microscopy

Ion implantation and low-temperature epitaxial regrowth of GaAs

Channeling and transmission electron microscopy have been used to investigate the parameters that govern the extent of damage in ion‐implanted GaAs and the crystal quality following capless furnace annealing at low temperature (∼400 °C). The implantation‐induced disorder showed a strong dependence on the implanted ion mass and on the substrate temperature during implantation. When the implantation produced a fully amorphous surface layer the main parameter governing the regrowth was the amorphous thickness. Formation of microtwins after annealing was observed when the initial amorphous layer was thicker than 400 Å. Also, the number of extended residual defects after annealing increased linearly with the initial amorphous thickness and extrapolation of that curve predicts good regrowth of very thin (<400 Å) GaAs amorphous layers produced by ion implantation. A model is presented to explain the observed features of the low‐temperature annealing of GaAs

X-ray rocking curve study of Si-implanted GaAs, Si, and Ge

Crystalline properties of Si-implanted GaAs, Si, and Ge have been studied by Bragg case double-crystal x-ray diffraction. Sharp qualitative and quantitative differences were found between the damage in GaAs on one hand and Si and Ge on the other. In Si and Ge the number of defects and the strain increase linearly with dose up to the amorphous threshold. In GaAs the increase in these quantities is neither linear nor monotonic with dose. At a moderate damage level the GaAs crystal undergoes a transition from elastic to plastic behavior. This transition is accompanied by the creation of extended defects, which are not detected in Si or Ge