QUANTUM TRANSPORT OF BURIED SINGLE-CRYSTALLINE COSI2 LAYERS IN (111)SI AND (100)SI SUBSTRATES

Magnetoresistance data for clean crystalline CoSi2 layers were analyzed in terms of weak localization, Coulomb interactions, and superconducting fluctuations. The CoSi2 layers with thicknesses of 11.5 nm in (111)Si and 23 nm in (100)Si were fabricated by high-dose ion implantation and subsequent annealing in a rapid thermal annealer (known as ion-beam synthesis or mesotaxy). The magnetic-field dependence of the resistance is interpreted in terms of two-dimensional weak localization with strong spin-orbit interaction and an additional classical contribution proportional to H-2. No indication of magnetic scattering was found, which is a sign of the ''cleanness'''of the samples. Long phase-coherence lengths of l(phi) almost-equal-to 0.75 mum in (111)Si and l(phi) = 2.3 mum in (100)Si at 4.2 K were determined by fitting the magnetoresistance data. The inferred inelastic-scattering time is interpreted as a sum of a clean-limit electron-electron process (dominant at temperatures below almost-equal-to 6 K) and an electron-phonon process dominant at higher temperatures. We further observed a general orientation dependence of the electrical transport properties of mesotaxial CoSi2 layers, such as anisotropy in the residual resistance, Hall coefficient, and the prefactor for the classical H-2 dependence of the magnetoresistance. This is probably related to multiple-band effects in CoSi2.