Surface reconstructions and transport of epitaxial PtLuSb (001) thin films grown by MBE

Abstract

This work presents the surface reconstructions and transport properties of the topological insulator PtLuSb grown on Al0.1In0.9Sb/GaAs (001). Two stable surface reconstructions, (1x3) and c(2x2), were observed on PtLuSb (001) surfaces. Antimony-dimerization was determined to be the nature of the (1x3) surface reconstruction as evidenced by chemical binding energy shifts in the antimony 4d core-level for surface bonding components. The two surface reconstructions were studied as a function of Sb4 overpressure and substrate temperature to create a reconstruction phase diagram. From this reconstruction phase diagram, a growth window from 320 °C to 380 °C using an antimony overpressure was identified. Within this window, the highest quality films were grown at a growth temperature of 380 °C. These films exhibited lower p-type carrier concentrations as well as relatively high hole mobilities. 1.

A simple electron counting model for half-Heusler surfaces

“…We expect group V dimer stability for n Ln = 1/3 (half-filled dangling bonds) or n Ln = 2/3 (filled dangling bonds). This is consistent with the c (2 × 2) surface of PtLuSb, for which recent x-ray photoelectron spectroscopy (XPS) measurements found evidence for Sb-Sb dimers ( 31 ). The previously observed trivial surface states ( 4 ) are likely of group V dangling bond origin but could be pushed significantly below E F via control of the surface Ln concentration or surface electron doping, for example, via alkali metal deposition.…”

Semi-adsorption-controlled growth window for half Heusler FeVSb epitaxial films

“…Films grown at a higher temperature of 560 • C reach a higher peak mobility than films grown at 500 • C, which we attribute to increased atomic site ordering at higher growth temperature. The maximum mobility of 41 cm 2 /Vs at 300 K for FeVSb films grown inside a growth window is comparable to previously reported mobilities of epitaxial half Heusler films grown on MgO (001), but is smaller than the highest mobilities reported for films grown on III-V substrates such as InP (001) [23,31,35]. We attribute the reduced mobility to antiphase domains that form as a result of growing a (001)-oriented half Heusler film (2-fold rotational symmetry) on a rocksalt MgO (001) substrate (4-fold rotation).…”

“…The Zcontrast high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) image in Fig. 1 (a [22,24,25,31]. To understand the origin of this (2 × 1) surface reconstruction, we performed photon energydependent photoemission spectroscopy measurements at beamline 29-ID of the Advanced Photon Source (Fig.…”

Heusler interfaces—Opportunities beyond spintronics?

“…4b). These formal charges are based on an electron counting model [50] that accurately predicts the experimentally measured surface reconstructions of TiCoSb (001), and is consistent with the experimental data for LuPtSb [119,120], MnNiSb [48], and TiNiSn (001) [121].…”