Weak localization and correlation effects in thin-film degenerate n-type silicon

Abstract

The magnetoconductance of thin-film n-type silicon has been studied in order to provide insight into the low-temperature behavior of recent silicon-based semiconductor-metal hybrid structures. There is considerable interest in such structures as potential candidates for creating nonmagnetic read-head sensors for ultrahigh-density recording. The magnetoconductance of thin-film silicon was therefore analyzed as a function of magnetic field orientation at temperatures ranging from T=4.2 to 300 K. At low temperatures, the magnetoconductance consists of two components that are attributed to weak localization and correlation effects. Surprisingly, the thin-film transport properties behave two-dimensionally for the localization contribution, whereas the correlation contribution is isotropic. Similar two-dimensional localization behavior has previously been reported for silicon inversion layers but was not expected for silicon systems with a finite thickness. An analysis of the magnetoconductance as a function of magnetic field orientation has verified that the localization contribution depends only on the perpendicular to plane component of the field. The Hall coefficient was observed to vary with magnetic field, providing further evidence for a magnetoconductance governed by electron-electron interactions. Fitting of the data at T=4.2 K and for low magnetic fields provided values for the localization parameter α, the inelastic scattering time τi, and the two-dimensional effective electron screening constant F̃σ.