Classical in-plane negative magnetoresistance and quantum positive magnetoresistance in undoped InSb thin films on GaAs (100) substrates

Magnetoresistance (MR) effects have been investigated in perpendicular and parallel magnetic fields at 300, 80 K and liquid He temperatures for undoped InSb thin films 0.1-2.3 mum thick grown on GaAs(100) substrates by MBE. At high temperatures, the intrinsic carriers show the parabolic negative MR observable only in magnetic fields parallel to the film. The skipping-orbit effect due to surface boundary scattering in the classical orbits in the plane vertical to the film has been argued to be responsible for the negative MR. At low temperatures (T = 80 K), the transport is dominated by the two-dimensional (2D) electrons in the accumulation layers at the InSb/GaAs(100) hetero interface; MR is positive and shows a logarithmic increase with anisotropy between parallel and perpendicular field orientation, arising from the 2D weak anti-localization (WAL) that reflects the interplay between the spin-Zeeman effect and strong spin-orbit interaction caused by the asymmetric potential at the interface (Rashba term). The zero-field spin splitting energy of Delta(0)similar to13 meV, the electron effective mass of m*similar to0.10m(0) seven times of the band edge mass in bulk InSb and the effective g-factor of |g*|similar to15 in the accumulation layer have been inferred from fits of MR for the 0.1 mum thick film to the 2D WL theory. (C) 2003 Elsevier B.V. All rights reserved.