Magnetoresistance fluctuations in shortn-type Si/SiGe heterostructure wires

Abstract

Magnetoresistance fluctuations in short quasiballistic Si/SiGe wire segments have been investigated as a function of magnetic field and temperature. The segments are measured in a four-probe geometry and the voltage probe distances L are taken smaller or larger than the phase coherence length l ͑Ϸ1.5 m at T ϭ0.1 K͒ and the electron mean free path l e ͑Ϸ0.8 m͒. At magnetic fields smaller than Bϭ1 T, the amplitude ␦R and the correlation field B c of both the symmetric and antisymmetric part of the resistance fluctuations have been studied as a function of probe distance and temperature. It is found that, despite the quasiballistic character of electron transport in our samples, the behavior of the amplitude and correlation field with probe separation is in good qualitative agreement with expressions derived for the diffusive regime. The observed magnitude of B c , however, is much larger than expected for the diffusive transport regime. A better agreement for B c is obtained using an expression adapted for the quasiballistic regime. The temperature dependence of the correlation field cannot be explained by expressions appropriate for the diffusive or the quasiballistic transport regime.

Silicon–Germanium Nanowires: Chemistry and Physics in Play, from Basic Principles to Advanced Applications

“…Top-down nanowires are in principle more amenable to mass serial production, but atomically precise and truly nano structures, smooth facets, and some of the most important configurations that we will describe, such as core–shell structures, inherently belong with bottom-up synthetic nanowires. Nevertheless, some very interesting works based on top-down SiGe nanowires have been reported, covering many topics in fundamental physics, such as quantized conductance of nanoconstrictions, single-electron devices, Coulomb blockade, , and the magnetoresistance of quasi-ballistic wires. , The interested reader is referred to the original publications.…”