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

Magnetoresistance data for clean crystalline CoSi2 layers were analyze d in terms of weak localization, Coulomb interactions, and superconduc ting fluctuations. The CoSi2 layers with thicknesses of 11.5 nm in (11 1)Si and 23 nm in (100)Si were fabricated by high-dose ion implantatio n and subsequent annealing in a rapid thermal annealer (known as ion-b eam synthesis or mesotaxy). The magnetic-field dependence of the resis tance is interpreted in terms of two-dimensional weak localization wit h strong spin-orbit interaction and an additional classical contributi on proportional to H-2. No indication of magnetic scattering was found , which is a sign of the ''cleanness'''of the samples. Long phase-cohe rence 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 magnetor esistance data. The inferred inelastic-scattering time is interpreted as a sum of a clean-limit electron-electron process (dominant at tempe ratures below almost-equal-to 6 K) and an electron-phonon process domi nant 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 coefficie nt, and the prefactor for the classical H-2 dependence of the magnetor esistance. This is probably related to multiple-band effects in CoSi2.