Weak Anti-Localization in the Accumulation Layer of InSb/GaAs (100) Hetero Interface

Abstract

Weak anti-localization (WAL) which reflects a strong spin-orbit (SO) interaction had been extensively studied in metal films where the effect comes from heavy host atoms or heavy impurities. WAL in semiconductor two-dimensional (2D) systems such as GaAs and InAs inversion layers and InAlAs/InGaAs/InAlAs quantum wells has also been observed, having been attributed to the spin dephasing due to the zero-field spin splitting. Moreover, the Zeeman splitting due to an applied magnetic field possively affects the WAL. High-mobility InSb thin layers are often grown on semi-insulating GaAs by means of molecular beam epitaxy (MBE). However, the growth on GaAs, in particular, (100) substrates is accompanied by high-density misfit dislocations (dangling bonds) at the InSb/GaAs hetero-interface because of the large mismatch (∼14 %) of lattice constants between InSb (6.48 A) and GaAs (5.65 A), producing the extraordinarily large carrier accumulation at the interface.7−9) In this paper, we reveal the peculiar features in lowtemperature magnetoresistance (MR) in an undoped InSb thin film grown on GaAs(100) substrate by MBE. In such films, almost whole carriers fall into the accumulation layer at the InSb/GaAs interface at low temperatures, resulting in the advent of positive MR which arises from the 2D WAL which reflects the interplay between the spin-Zeeman effect and strong spin-orbit (SO) interaction caused by the underlying band structure.