Weak anti-localization properties of high-quality topological Bi2Te3 nanofilms prepared by home-built pulsed laser enhanced molecular epitaxy system

Efficient preparation of high-quality topological insulator nanofilms (TINFs) in large scale is demanding. Using a home-built pulsed laser enhanced molecular epitaxy system (PLEES), we efficiently fabricate TINFs with prefect stoichiometry using Bi2Te3 TINFs as an example. Instead of utilizing multiple beam source furnaces to provide essential elements, hybrid targets containing both pure Bi2Te3 and Te targets are applied in a single epitaxial chamber. Moreover, diffraction pattern of growing Bi2Te3 TINFs are monitored in live by a high-energy electron diffractometer, allowing fast optimization of growth conditions. Scanning electron microscopy and atomic force microscopy demonstrate that the surface morphology of the prepared Bi2Te3 nanofilms with a thickness of 70 nm are flat and dense, and energy-dispersive X-ray spectroscopy analysis suggests that the ratio of Bi to Te elements is 2:3. The grazing incidence X-ray diffractometer reveals that the X-ray diffraction peaks of the synthesized nanofilm matches those of the Bi2Te3 standard PDF card. The prepared nanofilm exhibits a weak anti-localization effect at low magnetic fields characterized by physical property measurement system, confirming its unique electrical transporting properties. This work demonstrates that using hybrid targets with optimized growth parameters enable PLEES to efficiently grow high-quality stoichiometric TINFs on a large scale.