Introduction of Sr into Bi2Se3 thin films by molecular beam epitaxy

TL;DR

This paper reports the successful synthesis and characterization of Sr-doped Bi2Se3 thin films via molecular beam epitaxy, revealing structural and electrical changes but no superconductivity at low temperatures.

Contribution

First demonstration of Sr incorporation into Bi2Se3 thin films using molecular beam epitaxy with detailed structural and electrical analysis.

Findings

Sr substitutes for Bi and occupies interstitial sites.

Increased Sr content leads to higher n-type doping.

No superconductivity observed down to 1.5K.

Abstract

SrxBi2Se3 is a candidate topological superconductor but its superconductivity requires the intercalation of Sr by into the van-der-Waals gaps of Bi2Se3. We report the synthesis of SrxBi2Se3 thin films by molecular beam epitaxy, and we characterize their structural, vibrational and electrical properties. X-ray diffraction and Raman spectroscopy show evidence of substitutional Sr alloying into the structure, while transport measurements allow us to correlate the increasing Sr content with an increased n-type doping, but do not reveal superconductivity down to 1.5K. Our results suggest that Sr predominantly occupies sites within a quintuple layer, simultaneously substituting for Bi and as an interstitial. Our results motivate future density functional studies to further investigate the energetics of Sr substitution into Bi2Se3.