Domain engineering of epitaxial (001) Bi2Te3 thin films by miscut GaAs substrate

Abstract

Herein, we have reported domain engineering of epitaxial (001) Bi2Te3 thin films by miscut (100) substrates. On a nominal flat (100) GaAs substrate, two-variant domains that were in-plane rotated by 60 degrees, including the 60 degrees domain boundaries, were formed in the epitaxial Bi2Te3 film, such that the symmetry elements of two-fold rotational and/or mirror symmetries of the GaAs substrate were preserved. The domain variants were successfully reduced to obtain mono-domain Bi2Te3 thin films without any domain boundaries using the 2 degrees-miscut GaAs substrates, where a particular step-and-terrace structure on the vicinal surface macroscopically broke the intrinsic symmetry of GaAs, lowering the number of possible domains. Depending on the miscut directions, the in-plane orientations of the mono-domain Bi2Te3 films were varied with respect to the GaAs substrate. A model was proposed to explain the effect of miscut substrate on the domain structure of Bi2Te3 thin films. Low-temperature Hall measurements revealed that in the intrinsic regime (10 K) the electron concentration of the mono-domain Bi2Te3 films (similar to 2 x 10(18) cm(-3)) was significantly lower than that of the two-domain films (similar to 10(19) cm(-3)). This was attributed to the donor-like effect of the 60 degrees domain boundaries. These results provide an opportunity not only to integrate the single-crystalline, mono-domain, layered-chalcogenides on semiconductor single crystals, but also to manipulate their electronic transport properties by domain engineering. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.