12201-89-7Relevant articles and documents
Resistance anomaly and structural disorder in NiSi2 under high pressure
Garg, Alka B.,Vijayakumar,Verma,Rao,Godwal
, p. 367 - 372 (2007)
Results of X-ray diffraction, electrical resistance, thermoelectric power measurements and electronic band structure calculations on NiSi2 under high pressure are reported. The thermoelectric power (TEP) changes sign near 0.5 GPa (from +30 to -20 μV/K). As the pressure is increased, the value of TEP increases further in magnitude and near 7 GPa it becomes -50 μV/K. The pressure vs. resistance curve measured up to 30 GPa using diamond anvil (DAC)-based technique exhibits a broad hump near 12 GPa and exhibits hysteresis on pressure release. The ADXRD patterns up to 42 GPa show a gradual irreversible loss of long-range order in NiSi2 with the diffraction lines progressively broadening under pressure. The FWHM of the diffraction lines show a rapid increase in the half-widths close to 0.5 GPa and also near 12 GPa. The computed band structure at a compression (without any disorder) corresponding to 12 GPa, exhibits an electronic topological transition (ETT). The rapid increase in disorder above 12 GPa implies that the ETT may be facilitating the structural disorder. It is suggested that the pressure drives the material through a region of entropic and energetic barriers and induces disorder in the material.
Growth behaviour of epitaxial NiSi2 islands of A- and B-types during the reaction of nickel vapour with the Si(111) surface
Hesse,Mattheis
, p. 67 - 80 (1989)
Epitaxial NiSi2 islands of both A- and B-orientation were grown in UHV by the reaction of nickel vapour with Si(111) surfaces at 670 K. Habit, structure, and relative volume share of A- and B-type islands, respectively, were investigated in plane view and cross section by SAED and TEM (diffraction contrast at 1 MV; high resolution at 400 kV) for different amounts of deposited nickel. A-type islands grow with a three-dimensional shape, B-type islands with a more two-dimensional shape. Both types of islands are bounded by {111}Si faces, which represent {111} faces for the A-NiSi2 lattice, but {111} and lateral {151} faces for B-NiSi2. A-type islands grow about 10 times more rapidly than B-type ones. The observations are discussed with respect to R.T. Tung's model related to growing uniformly oriented NiSi2 films.
Structure change of Ni(1 ML)/Si(1 1 1) by post-annealing observed by atomic force microscopy, ion scattering and photoelectron spectroscopy
Hoshino,Nishimura,Taki,Asami,Sumitomo,Kido
, p. 112 - 120 (2002)
Structure change of Ni(1 ML: 7.83 × 1014 atoms/cm2)/Si(1 1 1) by post-annealing was observed by reflection high energy electron diffraction, atomic force microscopy (AFM), medium energy ion scattering (MEIS) and photoelectron spectroscopy. The AFM observation showed dramatic change of the surface morphology after the Ni deposition at room temperature (RT) followed by annealing at 400, 600, 700 and 800 °C for 2 min in an ultrahigh vacuum. MEIS using 70 keV He+ ions analyzed the depth profiles of Ni and the crystallographic structure of the Ni-composites formed by annealing. The valence band and the Si-2p and Ni-3p core level analyses using synchrotron-radiation light showed that the NiSi phase appeared by 1 ML-Ni deposition at RT and both NiSi and NiSi2 islands were formed by annealing at 400 °C. Annealing at 600 and 700 °C led to growth of the B-type NiSi2 islands with height of four and six Si-Ni-Si triple layers. After annealing at 800 °C, three-fourth of the deposited Ni atoms were dissipated from the surface and the dominant surface structure was the 1 × 1-ring clusters accompanied by a small amount of √19 × √19 phase. The present analysis clearly showed the structure change of Ni (1 ML)/Si(1 1 1) by post-annealing and provided the information about the kinetics for the Ni-Si system.
Formation of NiSi-Silicided p+n Shallow Junctions Using Implant-Through-Silicide and Low-Temperature Furnace Annealing
Wang, Chao-Chun,Lin, Chiao-Ju,Chen, Mao-Chieh
, p. G557-G562 (2003)
NiSi-silicided p+n shallow junctions are fabricated using BF2+ implantation into/through thin NiSi silicide layer (implant-through-silicide technology) followed by low-temperature furnace annealing (from 550 to 800°C). The NiSi film agglomerates following a thermal annealing at 600°C and may result in the formation of discontinuous islands at a higher temperature. The incorporation of fluorine atoms in the NiSi film can retard the formation of film agglomeration and thus improving the film's thermal stability. The forward ideality factor of about 1.02 and the reverse current density of about 1 nA/cm2 can be attained for the NiSi (310A)/p+n junctions fabricated by BF2 + implantation at 35 keV to a dose of 5 × 1015 cm-2 followed by a 650°C thermal annealing; the junction formed is about 60 nm measured from the NiSi/Si interface. Activation energy measurement indicates that the reverse bias junction currents are dominated by the diffusion current, indicating that most of the implanted damages can be recovered after annealing at a temperature as low as 650°C.
Electrical and structural properties of nanoscale NiSi2 precipitates in silicon
Riedel,Schroeter
, p. 7150 - 7156 (2000)
Structurally well-defined NiSi2 platelets of two {111}-silicide lattice planes thickness and 37 nm diameter form after in-diffusion of nickel in n-type silicon at 900°C followed by rapid quenching. These platelets are bounded by a dislocation ring and exhibit in deep-level-transient-spectroscopy (DLTS) measurements a line that can be attributed to bandlike electronic states at the extended defect. We exploit internal ripening of individual precipitates upon additional annealing at 320°C in order to study the temporal evolution of their electrical and structural properties. Within a short time of about 1 min one observes a continuous transmutation of DLTS line characteristics, finally revealing localized states at the defect. Structural changes towards a compact shape become observable by means of transmission electron microscopy on a significantly larger time scale of several minutes. We conclude that the bounding dislocation ring determines the electrical activity of platelets as-quenched. Due to its particular core structure, the dislocation exhibits characteristics of a quantum wire. A specific core defect that allows us to construct curved dislocation line segments causes meandering, which has been shown to be the weakest perturbation of ideal one-dimensional behavior.
Synthesis, crystal structure, and physical properties of the type-I clathrate Ba8-δNix□y Si 46- x - y
Aydemir,Candolfi,Ormeci,Borrmann,Burkhardt,Oztan,Oeschler,Baitinger,Steglich,Grin, Yu.
, p. 4730 - 4741 (2012)
Type-I clathrate phase Ba8Nix□ySi 46-x-y (□= vacancy) was obtained from the elements at 1000 °C with the homogeneity range 2.4 ≤ x ≤ 3.8 and 0 ≤ y ≤ 0.9. In addition, samples with low Ni content (x = 1.4 and 1.6; y = 0) and small Ba deficiency were prepared from the melt by steel-quenching. Compositions were established by microprobe analysis and crystal structure determination. Ba 8-δNix□ySi46-x-y crystallizes in the space group Pm3n (No. 223) with lattice parameter ranging from a = 10.3088(1) A for Ba7.9(1)Ni 1.4(1)Si44.6(1) to a = 10.2896(1) A for Ba 8.00(3)Ni3.82(4)Si41.33(6). Single-crystal X-ray diffraction data together with microprobe analysis indicate an increasing number of framework vacancies toward compositions with higher Ni content. For all compositions investigated, Ni K-edge X-ray absorption spectroscopy measurements showed an electronic state close to that of elemental Ni. All samples exhibit metallic-like behavior with moderate thermopower and low thermal conductivity in the temperature range 300-773 K. Samples with compositions Ba7.9(1)Ni1.4(1)Si44.6(1) and Ba 7.9(1)Ni1.6(1)Si44.4(1) are superconducting with Tc values of 6.0 and 5.5 K, respectively.
Silicide coating on refractory metals in molten salt
Tatemoto,Ono,Suzuki
, p. 526 - 529 (2008/10/09)
For better oxidation resistance of refractory metals in air, the electroless coating of silicide in the molten salt was developed in open air at 973-1173 K. The molten salt consists of NaCl, KCl, Na2SiF6 and Si powder, where the prop
