An investigation of the structure of amorphous Si1−xNix through the metal-insulator transition

Abstract

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Metal-insulator transition in amorphousSi1−xNix:Evidence for Mott’s minimum metallic conductivity

“…However, the existence of crystalline regions with diameters below 2 nm cannot be excluded. Such a clustering is suggested by [51], cf. [60].…”

“…However, due to the differences between the phase diagrams of the systems Si-Ni and Si-Cr, see Section I, the following hypothesis is suggested: If, instead of the Ni-Ni distance, the distance between metallic NiSi 2 grains were the relevant length for σ mm , the relatively small value of σ mm in a-Si 1−x Ni x might result from the formation of NiSi 2 crystalline regions with a diameter of the order of 1 to 2 nm, cf. [51,60]. Corresponding structural studies would be interesting.…”

“…Moreover, in the vicinity of the MIT, the electronic structure of a-Si 1−x Ni x was recently studied by XPS and UPS [50]. For a-Si 1−x Ni x :H, a structure study [51], optical conductivity measurements [52], also under pressure [53], and electronic structure investigations by XPS and XES [54] were reported in the literature. Last but not least, some of the authors have gained detailed experience in trying fits of σ(T ) by conventional theories for a-Si 1−x Ni x samples prepared by electron-beam evaporation in Tel Aviv [55,56].…”

Electronic Transport in Alloys with Phase Separation (Composites)

“…The schema shown in Section 2.1 can be applied to all the other transport parameters provided that a current density can be defined which is a function of a gradient of a potential, analoguously to Equation (2). For the thermal conductivity the corresponding relations read…”

“…Regarding point (2), the combinatorial development of materials seems to be a proper method for experimental studies. From this method (applied to a certain material system) a large range of different compositions can be realized concurrently on one large substrat, for instance by deposition of thin films by simultaneous co-sputtering from two or three targets on a large substrat.…”