Growth silicides

Low-temperature solvents are not readily available for many refractory compounds and semiconductors of interest. Molten salt electrolysis is utilized in many instances, as for the synthesis and deposition of elemental materials such as Al, Si, and also a wide variety of binary and ternary compounds such as borides, carbides, silicides, phosphides, arsenides, and sulfides, and the semiconductors SiC, GaAs, and GaP and InP [16], A few available reports regarding the metal chalcogenides examined in this chapter will be addressed in the respective sections. Let us note here that halide fluxes provide a good reaction medium for the crystal growth of refractory compounds. A wide spectrum of alkali and alkaline earth halides provides... 

We also observed growth of SiNW from Au nanoparticles. In this case, H2 was also necessary. Although Au silicides can form at moderate temperatures and can also be reduced by hydrogen to Au nanoparticles and silane, the growth temperature for SiNW was still above 1000°C. It seems that silane was produced in both Au and Co catalytic growth cases. 

This leaves to only one possibility, namely that Si gets first into the gas phase to enable the catalytic growth of nanowires via Co or Co silicide nanoparticles. For silicon... 

Proposed Growth Models. Summarizing the results given above, the growth mechanisms are proposed as follows. Because of the location of nanoparticles at the tips of SiNW, we conclude that growth must occur in the gas phase. More precisely, we think that Co silicide SAN play a role here. They help convert Si and H2 into SiH4 (gas). Unreacted Co nanoparticles left on the surface, possibly due to the... 

A schematic of the proposed growth model is shown in Fig. 10.23. In this model, Co nanoparticles play a dual catalytic role. On the one hand, they catalyze silane formation by reacting first with silicon to form Co silicides, and then react with hydrogen to form silane while being reduced to Co metal. The second role of Co nanoparticles is their classic catalytic ability of making nanowires by first dissolving the silane and precipitating out Si nanowires. 

Silicide layers can also be grown on Pt surfaces.247 The preferential facets of epitaxial growth are the 111. Atom-probe data reveal that the stoichiometry of the silicide phase is Pt2Si, and the Pt-Pt2Si interface is also very sharp. However, a small fraction of silicon atoms can diffuse into the Pt matrix. Formation of silicide layers on a nickel emitter surface is much more complicated where silicide layers of varying stoichiometries are formed.246,247 Owing to the statistical nature of the atom-probe data, identification of all the silicide phases in a nickel silicide layer is at best uncertain. 

In another example of SPE, a single crystal Si substrate with a 1000X thick Pd layer covered with lym of amorphous Si was heated to produce Pd9Si (13). As the Pd2Si reaction proceeds the thickness of the amorphous layer decreases and epitaxial Si is grown under the silicide layer. RBS, SIMS and AES were used to study the kinetics of the reaction. Substrate orientation and the concentration of carbon in the amorphous layer were found to be important factors in the rate of SPE growth. 

J.E.E. Baglin, H.A. Atwater, D. Gupta, F.M. d Heurle. Radioactive Ni tracer study of the nickel silicide growth mechanism // Thin Solid Films - 1982 - V.93 - P.255-264. 

K. Radermacher, S. Mantl, Ch. Dieker, H. Ltith, C. Freiburg. Growth kinetics of iron silicides fabricated by solid phase epitaxy or ion beam synthesis // Thin Solid Films.- 1992.-V.215, No.l.- P.76-81. 

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